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1 INTRODUCTION The urgency of the thesis: In our country, vibrator has been used for a long time [10], however; until now, there has not been an author or a project interested in researching and developing a full scientific basis and intensive calculation for design, as well as calculating the choice of vibrator during construction in geological conditions in Vietnam Therefore, the study of calculating the process of driving sheet pile into laminated soil by vibrating on the basis of nonlinear analysis of the interaction between soil layers and sheet pile in the working process is urgent, with high scientific and practical significance, but up to now, no author has been interested in this study yet, especially the problem of determining the reasonable technical parameters of vibrator on the viewpoint of research system "Vibrator - sheet pile - laminated soil" to create a scientific basis for calculating, designing or improvement of efficiency through using of vibrator for constructing Research objectives: Researching and developing methods to determine reasonable technical parameters of vibrator to driving sheet pile into laminated soil and research applications for specific cases to identify reasonable parmater of VH-QTUTC70 NSP-IIw vibrator, driving NSP-IIw sheet pile to laminated soil at Dong Quang Bridge, Ba Vi district of Hanoi Research object - Free-hanging vibrator: The thesis chooses the suspended vibrator hang on crane, with vibrating frequency from 20 to 40 Hz as the research object, because this vibrator is widely used for construction - U-shaped sheet pile: This is a common sheet pile and is currently used in construction in Vietnam, and the structure of this type of sheet pile is also suitable for theoretical and experimental research - Laminated soil: This is a popular and typical geological structure in Vietnam, consisting of layers of sand and clay which are classified with different thicknesses Research content - Researching to set up theoretical model and calculation program to determine technical parameters of "Vibrator - sheet pile - laminated soil " - Studying for selection of soil model and the theory of calculating of dynamic resistances of soil layer acting on sheet pile in the process of sheet pile driving by vibrator - Researching and developing the calculation method and program to determine the reasonable technical parameters of vibrator for driving sheet pile into laminated soil by genetic algorithm - Experimental study to determine the resistances and experimental coefficients, complete the input data set for the problem of determining the reasonable technical parameters of vibrator driving sheet pile into laminated soil - Determining the liquefied coefficient and the fluidized coefficient of some soil types in a specific case Scientific and practical significance of the thesis - Establishing methods and programs to calculate the problem of using vibrator driving sheet pile into laminated soil which is serve not only for sheet pile but also for other types of pile such as steel pile, concrete pile , it is possible to apply this calculation program to calculate and design vibrator in the country 2 - Researching and applying genetic algorithms and building computerized programs to determine reasonable technical parameters of vibrator driving sheet pile into laminated soil, these parameters can be used to calculating, designing, selecting and using vibrator - Experimental research process with reasonable experimental process and modern measuring equipment create the basis for the construction of experimental methods - Experimental study to determine the dynamic resistances of the soil on sheet pile when it is driven by vibrator, determine the liquefied coefficient and the fluidized coefficient of dynamic resistance of some soil types for use in calculate, design and operation of vibrator The novelty of the thesis: - Researched the dynamics of "Vibrator - sheet pile - laminated soil", including the establishment of mathematical model in consideration of interaction mechanism between soil layers and sheet pile under the effect of vibrating force, build algorithm diagram and calculation program - Researched the method of determining reasonable parameters of vibrator when driving sheet pile into laminated soil such as: building objective function, algorithm diagram and calculation program which has been applied calculations for a typical case - By empirical research method, it has determined the value of liquefied coefficient and fluidized coefficient of some soil types in Hanoi CHAPTER RESEARCH ON OVERVIEW OF THE SYSTEM "VIBRATOR SHEET PILE - LAMINATED SOIL" 1.1 The research works on the process of sheet pile driving vibrator announced 1.1.1 Domestic research projects It can be seen from published domestic research works: - Some authors study the dynamics of the process of pile driving by vibrator on the view of the mechanics problem of bar driving (absolute hard or elastic) into the elastic soil environment [4], [9] should not describe the complex behavior of the soil environment under the influence of driving force - Some authors have studied to build model and solve the dynamic problem of the pile driving process by vibrator through a mechanical model with a mass, taking into account the composition of the friction force against the side along the depth of pile driving [29] or a vibrator model with rigid pile in a flexible - elastic ground environment [3] The authors formulated the theoretical formula to determine the resistance components of soil to pile in terms of static force; and, method for calculating these resistance components in the working process have not been given - Some authors study the establishment of dynamic model [13] or analyze the choice of dynamic model of authors in the world [8], [11], [18] to apply for the particular case, then the recommendations are given for the calculation process, design or use of vibrator during the pile driving with the assumption that the pile is absolutely hard, soil is considered to be one layer and linear repulsive field Some authors conducted the empirical research on miniature experimental model so the results are different from reality [13] From the above analysis, the study of the process of driving sheet pile into laminated soil by vibrator is interested in determining the dynamic resistances between laminated soil and pile based on the interaction model between "soils - pile" is completely new content which has not mentioned in any research project so far 3 Soil Pile toe 11 Crane Hook Suspension housing Excitor block Clamp Sheet pile T(i) T(i)/4 T(i)/2 3T(i)/4 Clamp mc 1( 2( i( 1 Rs1 2 Rs2 Rsi T(i+1)/4 T(i+1) T(i+1)/2 Time (t) 3T(i+1)/4 Amplitude of excitation force Layer Layer Layer i i hi Amplitude of excitation force O Pkt h1 Liquefaction m2 h2 Degradation m1 Pkt The ground was vibrated Suspension housing Excitor block Dynamic mass, md = m2 + mc Soil Sheet pile is ace ing surf driv nd hen ator groued w vibr The form le by de t pi shee Mass of vibrator, mb = m1+m2 Initial ground surface Mass of total system, mtong = m1 + m2 +mc 1.1.2 Overseas research projects: Researching the process of pile driving with vibrator has been concerned by many authors in the world with many different approaches The differences in these studies are not only about the calculation model but also the method of determining the dynamic resistances between the soil and the pile or geotechnical parameters are taken into account Through analysis and evaluation of foreign research projects, we can see: - The research works in the world focus on groups of issues, including: studying the ability to pile driving with vibrator, studying the effect of pile driving process with vibrator to the surrounding environment and studying bearing capacity of pile - The process of pile driving by vibrator was studied by many authors,however; there exists many limitations, not fully and properly reflected in the actual working process, so the results are still limited and the Differencys are relatively large compared to practical [46] - Most authors assume that soil is uniform one layer to simplify the calculation process [46], [47], [39] , so the research results still have large Differencys (wide range of empirical coefficients) Since then, there has not been any study abroad to study the determination of technical parameters of vibrator driving sheet pile into laminated soil, interested in the interaction process between sheet pile with soil layers to determine dynamic resistances as mentioned by the thesis 1.2 The methods of determining the dynamic resistances of soil acting on sheet pile during driving by vibrator 1.2.1 Analyzing the process of sheet pile driving by vibrator The process of sheet pile driving by vibrator mounted on the base crane is shown in figure 1.12 Rti Figure 1.12 The whole process of sheet pile driving by vibrator Figure 1.13 Operation mechanism of "Vibrator sheet pile - laminated soil" When the vibrator acting, a part of the energy of the vibrator is transmitted to soil, stimulating the vibrating soil particles to create a liquid state (sand) and a fluidized state (clay), increasing the bore hole water pressure and reduce drag between soil layers with sheet pile [41], the remaining energy creates the driving force, when this force is greater than the total resistance of soil on the pile, the pile starts driving The operation mechanism of "Vibrator - sheet pile - laminated soil" system is shown in figure 1.13, with P0: is the tensioning force of lifting vibrator (if any), mb = m1 + m2 is the total amount of vibrator, mtong = m1 + m2 + mc is the total weight of the whole system (m1, m2, mc is the weight of the suspension frame, mass of vibrator and the weight of sheet pile), Pkt is the vibrating force of vibrators, h1, h2, , hi are the thickness of soil layers and R s1, Rs2, , Rsi and Rt1, Rt2, , Rti are respectively the dynamic resistance of these soil layers effect on shaft and toe pile The process of interaction between soil and sheet pile when pile driving with vibrator is a complex process and depends on many factors such as factors related to vibrator, soil foundation and sheet pile In particular, parameters of vibrator and ground are the most important parameters, deciding the mechanism of interaction between soil and soil or between soil and pile in the area around the pile, thereby giving a theoretical basis for calculation of dynamic resistance component 1.2.2 Selection of soil model and mathematical method to determine the dynamic resistances of soil layers on sheet pile driving by vibrator In mechanics, some basic model are used for soil such as: - Isotropic linear elastic model; - Elastic - pure plastic model; - Nonlinear elastic model; - Elastic-plastic-viscous model There have been many studies showing that the dynamic resistance Figure 1.17 Diagram showing the displacement of sheet of soil on sheet pile directly affects pile (a), dynamic resistance into pile (b) and pile driving forces (c) the pile driving process including components which are pile driving resistance (Rs)and pile driving force (Rt) Under the impact of the cycle load, these drag elements have a change in concept as shown in figure 1.17 So far in the world, some authors have built land model and mathematical model to determine the dynamic resistances of soil acting on steel pile under the impact of driving force, such as: Karlsruhe, Vipere [46] and Vibdrive mentioned in [46]; Seung-Hyun Lee [49]; Svetlana Polukoshko [56] and Alain Holeyham mentioned in [65], [44] In which the thesis selected Vibdrive model (sandy soil) and Alain Holeyham model (clay soil) to determine the dynamic resistances of soil on sheet pile (Chapter 2), because these model are smart, easy to apply, suitable for experimental research conditions in Vietnam 1.3 The optimal theoretical basis for determining reasonable parameters of vibrator during the process driving sheet pile into laminated soil According to [28], [32], [73], [31] in technical design, optimization is an important mathematical tool used to systematically improve design parameters to satisfy set goals This process is done by appropriately changing the value of the design parameters until the optimal value of the objective function is determined There are many different methods of potential optimization such as derivative method (weighted method; method of binding method, chord method ) or method of non - function (evolutionary planning; strategic progress evolution program such as genetic algorithms, metallurgical simulation algorithms, differential evolution algorithms ) Thus, there are many different methods to solve the optimization problem and can not show what the best method is Genetic algorithms are used effectively for optimal design problems in engineering, so the thesis uses "Genetic Algorithms" to solve the problem of determining reasonable technical parameters of vibrator in the process of driving sheet pile into laminated soil (Chapter 3) CONCLUSION OF CHAPTER 1 Vibrator is a device which is currently widely used in construction, but the theoretical basis for calculating, designing and choosing vibrator in our country is insufficient and inadequate On the basis of synthesizing and analyzing the results of the published domestic and foreign studies, the thesis selected the content of research to determine the reasonable technical parameters of vibrator for construction of sheet pile to laminated soil in consideration of interaction mechanism between soil layers and sheet pile in the working process, this is a completely new research direction which is not duplicated and has high practical meaning The determination of the dynamic resistances of soil acting on sheet pile based on the interaction mechanism between soil types and sheet pile when lowered by vibrator has a decisive meaning to the results, this math is the core problem of driving sheet pile into soil by driving force, however, in our country, there is no work of interest Based on the process of synthesizing and analyzing published research works in the world, the thesis has selected the land model and mathematical model to determine the dynamic resistances of soil on sheet pile Under the effect of driving force, the unit dynamic compression resistance at the toe (qd) and the unit dynamic shear resistance at the shaft pile (d) of the sandy soil layers are determined according to the The formula from 1.2 to 1.5, of the clay layers is determined according to the formula from 1.6 to 1.9 Research to determine the reasonable parameters of vibrator to driving sheet pile into laminated soil is a high scientific urgent issue, serving as a basis for completing the design of vibratory vibrator in the country and choosing vibrator, improving efficiency in exploitation and use This issue has not been mentioned by any author There are many optimal calculation methods, in which the method of applying genetic algorithms for optimal calculation in technical problems has many advantages, so the thesis chooses genetic algorithms to build methods for identification of reasonable parameters of vibrator to driving sheet pile into laminated soil CHAPTER RESEARCH SYSTEMS "VIBRATOR - SHEET PILE LAMINATED SOIL" 2.1 Building computer model for "Vibrator-Sheet pile-Laminated soil" 2.1.1 The problem As analyzed in Chapter 1, the thesis builds a model of two degrees of freedom for the "Vibrator - sheet pile - laminated soil in consideration of interaction between sheet pile and the surrounding soil layers to calculate their dynamic resistances on sheet pile, allowing proper description of the actual working conditions of the system, so that the calculation results will be more accurate and reliable Subjects of the system "Vibratorsheet pile - laminated soil" which thesis aim to: - Vibrator: The research object is vibrator consist of two-mass structure (suspenssor housing and excitor block), free-hanging and adjusting driving force through vibrating frequency adjustment and calculation for specific cases with VH-QTUTC70 vibrator manufactured by Vietnam - Sheet pile: The type of pile with single U section is single drived (without clutch friction), this is a type of sheet pile which is commonly used with firm hardness and it is suitable for research purposes The parameters of NSP-IIw sheet pile is used in the case of specific calculations - Laminated soil: The soil structure consists of many layers with different thickness and mechanical properties as objects of research and calculation for specific cases with geological structure at T2 and T3 abutment Dong Quang Bridge (Ba Vi, Hanoi) 2.1.2 Building a model of system "Vibrator - Sheet pile - Laminated soil" The thesis builds a theoretical model for the problem of sheet pile driving into laminated by vibrator as shown in figure 2.5 with assumptions: - Considering hardened sheet pile with z vibrator through hydraulic clamp, all z points on vibrator and sheet pile have the same displacement, acceleration, velocity and displacement; - Considering the driving force effect on vertical pile coinciding with the pile's shaft and acting at the top of the pile; - Vibration vibrator changes the Figure 2.5 Theoretical model driving frequency without changing the for system "Vibrator - sheet pile - laminated soil" eccentric moment; - The soil consists of many different layers with the thickness of h 1, h2, hi, it is considered that each layer is homogeneous and has its own characteristics Each soil layer is characterized by a soil model to determine dynamic resistances, the value of the dynamic resistances calculated in each cycle of the driving force, corresponding to the penetration depth of pile in those soil layers - Considering sheet pile is absolute rigidity and only fluctuating vertically - Consider the interaction environment of the soil around the pile is the same in any direction From the theoretical model (figure 2.5), we analyze the force and the obtained diagram as shown in figure 2.6 of which: - z1, z2: Displacement of supenssion housing and vibrator - sheet pile, m; - Fs: Elastic force of spring system, kN; - m1, m2, mc: Mass of supenssion housing, excitor block and sheet pile, kg; - Pkt: Driving force, kN; m1g Pqt1=m1z1 - Pqt1, Pqt2: Inertial force of supenssion z1 Fs housing and vibrator - sheet pile, kN; O x z Fs - Rs: Dynamic shaft resistance of soil layers acting on the pile Dynamic shaft Pqt2=(m2+mc)z2 Pkt resistance (Rs) is modeled by a ladder (m2+mc)g z2 function, in which the direction of the Rs Rt resistance is always opposite to the Figure 2.6 Diagram of force analysis acting on direction of motion of the pile, elements of model determined by the following formula: z > z sign( z )= 0 z = R s =sign( z ) d dz -1 z < with (2.25) In which: : Perimeter of sheet pile, m; d: Maximum shear stress at the shaft of the sheet pile (formula 1.3 for sandy soil and formula 1.9 for clay), kN / m2; z: Penetration depth of the sheet-pile toe, m m1 S Amplitude of excitation force m2 T(i) T(i)/4 O 3T(i)/4 T(i)/2 Pkt T(i+1)/4 T(i+1) 3T(i+1)/4 Time (t) T(i+1)/2 Pkt Amplitude of excitation force z ks1 Layer ks2 Rsi ksi Cti z hi ti Csi z Rs2 t2 Cs2 Layer Rs1 h2 Cs1 h1 mc t1 ti Layer i kti Rti z : Velocity of the vibratory - sheet pile, m/s; - Rt: Dynamic toe resistance, is determined by the following formula: z >0 q d A t (2.26) Rt = z In which: At: Area of pile toe, m2; qd: Driving unit resistance at the toe (formula 1.2 for sandy soil and formula 1.8 for clay soil), kN/m2; Since then we have developed the equations of motion of the system: m z +S(z -z )-m g=0 1 (2.28) (m +m )z -S(z -z )-(m +m )gM ω si n ( ω t )+R + R =0 c 2 c e s t 2.2 Build algorithm diagram and calculation program 2.2.1 Algorithm diagram Begin Input parameters: - The parameters of vibrator - The parameters of sheet pile - The parameters of soil layer Enter the input parameters: - The parameters of vibrator - The parameters of sheet pile - The parameters of soil layer - Set initial values: z10,z20, v10, v20, z0 Begin Call dynamic resistance of soil layers Rs(i), Rt(i) Number of calculatiing cycles i=1 Calculate Fd Fd + mtængg Rs(i) + Rt(i) i =1+1 Call sub-program diagram for calculating dynamic resistance of soil layers Rs(i), Rt(i) Fd + mtongg Rs(i) + Rt(i) Yes No No Sub- program diagram for calculating dynamic parameters: Call the program for solving motion equations system to determine the values: z®i(t); vtbi; zi(t); vi(t); ai(t) z(t); v(t); a(t) v®i(t); a®i(t) Pile goes down, Calculate vtb(i) Pile doesn't go down vtb(i) = Calculate the penetration depth: z(i) = z(i-1) + i*T*vtb(i) Yes Calculate: zi(t) = z(i) + z®i(t) vi(t) = v®i(t) ai(t) = a®i(t) Show and graph output such as: z(t); v(t); a(t), End End Figure 2.7 Program diagram for calculating sheet pile driving vibrator Figure 2.8 Sub- program diagram for calculating dynamic parameters Input parameters: a1 = h1 -z(i) Begin Yes Call program to calculate: Yes Call program to calculae: R1s(i) = R1s(z(i)) R1t(i) = R1t(z(i)) Calculate: Rs(i) = R1s(i) Rt(i) = R1t(i) No Calculate: R1s = Rs(h1) a2 = h1 + h2 -z(i) R2s(i) = R2s(z(i)-h1) R2t(i) = R2t(z(i)-h1) No Calculate: R2s = Rs(h1)+Rs(h2) Call program to calculate: R3s(i) = R3s(z(i)-h1-h2) R3t(i) = R3t(z(i)-h1-h2) Calculate: Rs(i) = R1s+ R2s(i) Rt(i) = R2t(i) Dynamic shaft and toe resistance: Rs(i), Rt(i) Number of soil layers: n= Thickness of each soil layer: hj (j=1 - n) Soil type of each soil layer Enter the properties of each soil layer Call the penetration depth z(i) End Calculate: Rs(i)=R2s+R3s(i) Rt(i)=R3t(i) Figure 2.9 Sub-program diagram for calculating dynamic resistance of soil layers 2.2.2 Building program: From the algorithm, applying Matlab software to build a program to calculate the process of driving sheet pile into laminated soil by vibratior (Appendix A.1) The reliability of the program of thesis is verified through comparing the results of the published research works in the world (Appendix A.3) 8 2.3 Analysis process of NSP-IIw sheet pile driving by VH-QTUTC70 vibrator into laminated soil at Dong Quang Bridge project (Ba Vi, Hanoi) 2.3.1 Input parameters - Parameters of VH-QTUTC70 vibrator: Structure of VH-QTUTC70 vibrator as shown in figure 2.10 and has the basic parameters as shown in Table 2.2 380 18 19 445 25 20 Ø85H7 n6 Ø85H7 n6 Ø85H7 n6 Ø85H7 n6 Ø90 H7 n6 Ø180n6 Ø180 n6 21 22 1060 d.18x30H7 n6 650 Ø150n6 Ø70H7 n6 23 260 Ø85 H7 n6 970 14 26 A 265 A-A C-C Ø85H7 n6 Ø85H7 n6 Ø180 n6 Ø85 H7 n6 d.10x90 H7 n6 d.10x90 H7 n6 Ø85 H7 n6 D 60 200 270 Right view Ø85H7 n6 D-D A Ø180 n6 27 13 Ø180 n6 D Ø85H7 n6 Ø85H7 n6 Ø85H7 n6 Ø180 n6 Ø85H7 n6 Ø90H7 n6 Ø180 n6 15 16 C B 24 17 Ø180 n6 260 Ø85H7 n6 Ø85 H7 n6 Ø85 H7 n6 11 Ø180 n6 740 Ø85H7 n6 d.10x90 H7 n6 Ø180 n6 240 Ø85H7 n6 Ø180 n6 d.10x90 H7 n6 260 Ø90H7 n6 3000 C 12 240 Ø85 H7 n6 Ø180 n6 60 d.10x90 H7 n6 19 260 B 10 d.10x90 H7 n6 10 760 480 445 28 60 265 B-B Front view Left view Rear view Clamp pinch Pinch of clamp head Cylinder pinch 4, 6, 15,17 Shaft of eccentric wheels 3, 2, 1, 5, 16 Transmission gear Spring bushing Shaft of spring Springs 10, 18 Upper and lower nuts 11 Cover 12, 13 Eccentric mass type 1, type 14 Hand 19 Spring nut 20, 21 Active and passive gears 22 Active gears bearings 23 Glove ring 24 Bearings 25 Suspension housing 26 Clamp 27 Excitor block 28 Hydraulic motor Figure 2.10 Vibration vibrator construction VH-QTUTC70 Table 2.2 Input parameters of VH-QTUTC70 vibrator No Parameter name Specified eccentric moment Weight of suspension housing Weight of the exciter block and clamp Driving frequency Stiffness coefficient of spring system Symbol Me m1 m2 f S Value 13,46 300 2200 15-36 30 Unit kg.m kg kg Hz kN/m - Parameters of sheet pile NSP-IIw: Table 2.3 Input parameters of NSP-IIw sheet pile No Parameter name Perimeter of sheet pile Sheet pile area Length of pile The mass of sheet pile Mass of 1m long sheet pile Inertia moment of pile sheet Symbol At lcọc mc gcvt Jcvt Value 1,5 1,04E-02 14,5 1183,2 81,6 5,22E-05 Unit m m2 m kg kg/m m4 - Parameters of soil base at Dong Quang Bridge project (Ba Vi, Hanoi): Geological structure at T2 and T3 abutment, Dong Quang Bridge is shown through abutment section of LKT2 (T2 abutment) and LKT2 (T3 abutment) geological borehole as shown in figure 2.11 and figure 2.12 Geology at T2 abutment and T3 abutment of Dong Quang Bridge has a laminated geological structure, where the sand and clay soil layers (table 2.4) are interwoven, with different thicknesses, this is a typical geological structure of Vietnam Table 2.4 Soil type at T2 and T3 abutment, Dong Quang Bridge Name of soil layer at T2 and T3 abutment, Dong Quang Bridge Small and medium-sized sand grains (layer 2, T2 abutment) Phase clay, semi-hard state (layer 3, T2 abutment and layer 3, T3 abutment) Particle sand is small and discrete (layer 1, T3 abutment) Medium-grained gravel sand mixed with clay, tight to medium density (layer 2, T3 abutment) Equivalent land alb,aIV3tb1 a,amIII2vp3 aIV3tb2 aIII2vp1 Project: Investment and construction of Dong Quang bridge Location: Ba Vi District of Hanoi and Thanh Thuy District of Phu Tho Province Process: Km0 - Km2+196,11 Project: Investment and construction of Dong Quang bridge Location: Ba Vi District of Hanoi and Thanh Thuy District of Phu Tho Province Process: Km0 - Km2+196,11 Category: Geology Design stage: Design of construction draw Category: Geology Design stage: Design of construction draw Geological borehole 5.07 13 15 13 15 2.04 6.9 9 15 26 10 10 15 27 12 10 17 29 14 25 M2 4.0-4.2 6a 25 26 7.89 -4.86 29 M3 6.0-6.2 M4 8.0-8.2 M6 12-12.2 14 3.0 Chart 10 20 30 40 50 Sampling depth (m) Depth ruler (m) SPT Index N 10 14 27 15 15 10 11 15 10 11 12 11 16 29 14 11 16 30 15 28 29 15 28 M1 2.0-2.2 27 M2 4.0-4.2 28 M3 6.0-6.2 29 M4 8.0-8.2 28 M5 10-10.2 29 M6 12-12.2 Phase clay, semi-hard state Shale is blue-gray, dark gray Strongly cracked 30 M7 14-14.2 -9.04 15.65 Shale is blue-gray, dark gray Weathered mild, hard -9.86 6a 6.2 2.0 -6.86 -2.84 9.45 M5 10-10.2 12 Medium-grained gravel sand mixed with clay Tight to medium density Phase clay, semi-hard state 27 N1 N2 N3 Particle sand is small and discrete 5.1 CPT Number of blows N/30cm 1.56 Depth of borehole: 19m Technical staff: Nguyen §inh Ngoc Checker: Hoang Quang Luan Geological description 6.61 1.56 M1 2.0-2.2 Small sized gray sand grains Medium tight Ratio: 1/100 Date: 16/04/2014 Drill: XY-1 Stratigraphic section No of layer Sand grains of small river beds are gray Chart 10 20 30 40 50 Layer elevation (m) N1 N2 N3 Layer thichkness (m) Depth ruler (m) Number of blows N/30cm SPT Index N CPT Geological description Borehole number: LKT3 Borehole elevation: 6.61 Process: Km0+365.03 Layer depth (m) 0.03 Geological borehole Depth of borehole: 17m Technical staff: Nguyen §inh Ngoc Checker: Hoang Quang Luan Sampling depth (m) Ratio: 1/100 Date: 15/04/2014 Drill: XY-1 Stratigraphic section Layer elevation (m) 7.11 0.03 Layer thichkness (m) No of layer Layer depth (m) Borehole number: LKT2 Borehole elevation: 7.11 Process: Km0+298.43 1.0 Shale is blue-gray, dark gray 2.0 Strongly cracked -10.04 16.65 17 Figure 2.11 LKT2 borehole Shale is blue-gray, dark gray Weathered mild, hard Figure 2.12 LKT3 borehole - The liquefied coefficient and fluidized coefficient of soils at T2 and T3 abutments used in the theoretical calculation program as shown in Table 2.5 (these coefficients are empirical research results in Chapter 4) Table 2.5 The value of experimental coefficients using in the program Frequency (f) Soil type Layer - Discrete, dark gray, small grained sand Layer - Brown gray clay phase, semi-hard state Layer - Discrete, dark gray, small grained sand Layer 2-Sand mixed with gravel, medium and fine gravel, tight to medium tight Layer - Brown gray clay phase, semi-hard state 15 Experimental coefficients Hz Abutment T2 toe 0,6 Liquid liquefied Pile 0,167 toe 0,6 Fluidized coefficient pile 0,16 Abutment T3 toe 0,6 Liquid liquefied pile 0,167 toe 0,191 Liquid liquefied pile 0,152 Fluidized coefficient 20 Hz 25 Hz 30 Hz 35 Hz 0,5 0,167 0,7 0,11 0,4 0,111 0,4 0,12 0,4 0,109 0,3 0,13 0,2 0,104 0, 18 0,17 0,5 0,167 0,179 0,4 0,111 0,247 0,4 0,109 0,243 0,2 0,104 0,116 0,166 0,117 0,109 0,116 toe 0,6 0,7 0,4 0,3 0, 18 pile 0,16 0,11 0,12 0,13 0,17 2.3.2 Calculation results with geological parameters at T2 abutment b) Displacement of pile at Z = m a) Total displacement of the pile c) Displacement of pile at Z = m Figure 2.14 Real displacement of the pile (Abutment T2, f = 30Hz) Figure 2.15 Acceleration of the pile (Abutment T2, f = 30Hz) Figure 2.17 Velocity of pile (Abutment T2, f = 30Hz) 10 Figure 2.19 Displacement of pile (Abutment T2, f = 30Hz a) Total dynamic shaft resistance b) Dynamic shaft resistance when t = c) Dynamic shaft resistance when t = 80 s Figure 2.22 Dynamic toe resistance (Abutment T2, f = 30Hz) a) Total dynamic toe resistance b) Dynamic toe resistance at t = s (layer 1) c) Dynamic toe resistance at t = 80s (layer 2) Figure 2.22 Dynamic toe resistance (Abutment T2, f = 30Hz) CONCLUSION OF CHAPTER On the basis of synthesizing, evaluating and analyzing the factors affecting the process of sheet pile driving by vibrator into laminated soil Set up a mathematical model for the process of sheet pile driving by vibrator into laminated soil (figure 2.11) in consideration of the interaction mechanism between soil and pile to determine the dynamic resistances of the soil layer (sandy or clay soil, these are typical types of soil geology in our country) to sheet pile Developed a calculation program to determine the technical parameters of the problem of sheet pile driving by vibrator into laminated soil on Matlab software The reliability of this program is verified by comparing the calculated results with the published results in the world Therefore, this program will be used to determine the reasonable technical parameters of vibrator in the "Vibrator - sheet pile - laminated soil" in Chapter 3 Applied this calculation program to the specifically case of VH-QTUTC70 vibrator driving NSP-IIw sheet pile into laminated soil at T2 and T3 Abutment of Dong Quang Bridge (Ba Vi, Hanoi) CHAPTER RESEARCH FOR DETERMINATION OF REASONABLE TECHNICAL PARAMETERS OF VIBRATOR WHEN DRIVING SHEET PILE INTO LAMINATED SOIL 3.1 Building methods to determine the reasonable technical parameters of vibrator when driving sheet pile into laminated soil 3.1.1 Problem estabishment Determining the reasonable technical parameters of vibrator when driving sheet pile into laminated soil is a complex nonlinear problem involving many input parameters such as parameters of vibrator and sheet pile, soil environment, in which soil parameters are nonlinear parameters that are difficult to define Table 3.1 Technical parameters of vibrator No Parameter name Specified eccentric moment, kg.m Symbol Me 11 Weight of suspension housing, kg Weight of the exciter block and clamp, kg Driving frequency, Hz Stiffness coefficient of spring system, kN.m/s m1 m2 f S From table 3.1, it can be seen that the selected vibrator object are characterized by five basic specifications, with each set of values of the above parameters corresponding to a vibrator operation mode Therefore, to adjust the operation mode of vibrator to optimize the process of driving sheet pile into laminated soil, it is necessary to determine the reasonable value of the above parameters when considering the "Vibrator - sheet pile laminated soil” It is possible to select one or all of the above parameters to calculate a reasonable value, which is of great significance for the calculation, design and exploitation of vibrator Therefore, in the general case, the thesis set up a problem to determine reasonable technical parameters of vibrator (all five parameters) to U-shaped sheet pile driving to laminated soil and applications in specific cases, the thesis only focuses on determining the fair value of two parameters: driving frequency (f) and mass of suspension (m1) of vibrator VH-QTUTCH70, considering the viewpoint of operation and usage, these two parameters can be easily adjusted directly during the vibrator operation The above parameters of vibrator are determined indirectly through the problem of multi-objective optimization, in which the objective function is to minimize the energy expenditure in the process of driving sheet pile into laminated soil by viberating vibrator in the depth of the pile when changing the input parameters of the vibrator Then it can determine the most suitable values for parameters of vibrator corresponding to each specific soil type 3.1.3 Set up mathematical model to identify reasonable parameters of vibrator a Target function: The objective function is represented by the following mathematical expression: m T (3.17) W m WT (2.π)2 ξ M e CFW(p)= In which: kW/m; z = i=1 i i z tb (Ti ) = i=1 z tb (Ti ).1000.μ f z (f,m1 ,m2 ,mc ,S,Me ,R t ,R s ) dt CFW (p): Function of energy consumption calculated to penetration depth, W: Total energy consumption of vibrator, kW; z: Penetration depth, m; b Reasonable parameters need to be determined: The technical parameters of the vibrator as shown in Table 3.1 c Binding conditions: - Conditions for binding of design parameters: pl p(f,m1, m1, Me, S) pu (3.18) Where: p : Lower limit vector of design parameters p; p (f, m1, m1, Me, S): Vector design parameters; pu: Upper limit vector of design parameters p - Binding Conditions on working conditions of the system: + Conditions to pile driving into soil by vibrator is the amplitude of vibration of sheet pile must be greater than the minimum limit amplitude value l 12 (3.19) z2 (f,m1,m2 ,mc ,S,Me ,R t ,R s ) [S0 ] In which: [S0]: The minimum limit amplitude value of the pile (table 2.1) z (f,m ,m ,m ,S,M ,R ,R ) : Absolute value of the vibration amplitude of sheet 2 c e t s pile, m z z max + Binding Condition for the total depth of pile: (3.20) with: zmax: Depth of pre-driving pile, m d The optimal problem: The optimal problem for determining the reasonable technical parameters of vibrator for driving sheet pile into laminated soil can be written in the following form: CFW(p)= pP n Ti W n WT i (2.π) ξ M e = = f z (f,m1 ,m ,m c ,S,M e ,R t ,R s ) dt z i=1 z tb (Ti ) i=1 z tb (Ti ).1000.η (3.21) l u p M ,m ,m ,f,S T e x1 p p p l l l l l l p M e ,m1 ,m ,f ,S u p : p M eu ,m1u ,m 2u ,f u ,Su z (m ,m ,m ,S,M ,R , R ) [S ] e t s 2 c 0 z z max With pl and pu are the lower and upper limit vectors of the design parameters p, So is the minimum limit amplitude value to ensure the pile driving into the soil layers (Table 2.1) 3.1.4 Building algorithms and to calculation programs of reasonable parameter 3.1.4.1 Building algorithm diagram Begin Make a new design parameters population p' Initialize of initial design parameters population p0 Design parameters population p' Mutation Call program "BRTL - CVT - §NL" to calculate W(p'), Ztb(p') Objective function: minCFW(p) p P Determine the fitness of individuals Crossover No Selection Yes Best solution Show output p* End Figure 3.2 Algorithm diagram of using genetic algorithm to solve the problem of determining reasonable parameters of vibrator when driving sheet pile into laminated soil 3.1.4.2 Establishment of caculation program for reasonable parameters Based on the set algorithm, set up a calculation program to determine the reasonable technical parameters of vibrator when sheet pile driving into laminted soil based on the application of genetic algorithms by Matlab software (Appendix A.2) and application of built-in program for specific cases to determine reasonable technical parameters of VH-QTUTCH70 vibrator (driving frequency - f and suspension mass - m1) NSP-IIw sheet pile driving to soils at T2 , T3 abutment of Dong Quang Bridge (Ba Vi, Hanoi) with the experimental coefficients defined in Chapter 13 3.2 Determining reasonable technical parameters of VH-QTUTCH70 vibrator when driving NSP-IIw sheet pile in to laminated soil at T2 and T3 abutment of Dong Quang Bridge (Ba Vi, Hanoi) 3.2.1 Reasonable parameters to be determined by VH-QTUTC70 vibrator Two technical parameters of VH-QTUTC70 vibrator for optimal calculation include: - The driving frequency of vibrator is found within f = 15-100 Hz; - The weight of suspension housing of vibrator is found within m1 = - 2000 kg 3.2.2 Input parameters: Including parameters in table 3.3 and other parameters of vibrator, sheet pile and soils are taken in section 2.3, Chapter Table 3.3 Input parameters of VH-QTUTC70 vibrator No Parameter name Experimental coefficient Mechanical transmission efficiency Hydraulic transmission efficiency Maximum depth of piles to optimize Symbol 0 ck tl zmax Value 1 0,98 Unit m 3.2.3 Calculation results of reasonable parameters Table 3.4:Reasonable technical parameters of vibrator No 1.1 1.2 2.1 2.2 3.1 3.2 4.1 4.2 5.1 5.2 Design parameters Symbol Value With medium-sized, dark-gray, medium-grained sandy soil (T2 abutment) Mass of suspension housing m1 1000 Driving frequency f 32,26 CFW 1,159 The target function With brown gray clay type, semi-hard state (T2 abutment) Mass of suspension housing m1 1400 Driving frequency f 20,85 CFW 2,124 The target function With a small, black, gray, small-grained sand (T3 abutment) Mass of suspension housing m1 1100 Driving frequency f 34,19 CFW 1,283 The target function With soil and clay mixed with gravel, medium and tight, tight (T3 abutment) Mass of suspension housing m1 1350 Driving frequency f 42,48 CFW 2,301 The target function With a kind of gray-brown clay, a half hard state (T3 abutment) Mass of suspension housing m1 1500 Driving frequency f 20,19 CFW 2,013 The target function Figure 3.3 The graph shows the process of finding reasonable parameters of vibrator with sandy soil of dark gray, medium-sized grain (T2 abutment) Unit kg Hz kW/m kg Hz kW/m kg Hz kW/m kg Hz kW/m kg Hz kW/m Figure 3.4 The graph shows the process of finding reasonable parameters of vibrator with brown gray clay phase, half hard state (T2 abutment) In order to assess the reasonableness of the found parameters, the thesis uses the set calculation program in Chapter to operate with the reasonable found parameters and 14 other random parameters of the vibrator for comparison and verification Based on that, the thesis has confirmed the reliability of the program and the results obtained Some specific comparison results: Figure 3.5 Displacement of pile (when f = 30, 32 and 35Hz) a) Acceleration of pile at t = 20 s b) Acceleration of pile at t = 40 s Figure 3.6 Acceleration of pile (when f = 30, 32 and 35Hz) a) Velocity of pile at t=20s b) Velocity of pile at t=40s Figure 3.8 Velocity of pile (when f = 30, 32 and 35Hz) a) Displacement of pile at t = 20 s b) Displacement of pile t = 40 s Figure 3.10 Displacement of pile (when f = 30, 32 and 35Hz) a) Dynamic shaft resistance b) Dynamic shaft resistance at t=10 s c) Dynamic shaft resistance at t=40 s Figure 3.12 Dynamic shaft resistance (when f = 30, 32 and 35Hz) a) Dynamic toe resistance b) Dynamic toe resistance at t=10 s c) Dynamic toe resistance at t=40 s Figure 3.13 Dynamic toe resistance (when f = 30, 32 and 35Hz) CONCLUSION OF CHAPTER Set up the smallest energy cost function (formula 3.42) to determine the reasonable technical parameters of vibrator Defined the input parameters (Section 3.2.1) and established a general program to determine the reasonable technical parameters of vibrator when driving sheet pile into laminated soil in consideration of the nonlinear interaction mechanism of dynamic resistances due to soil layers acting on sheet pile when working (Appendix A2) Applicated calculation program for specific cases with VH-QTUTC70 vibrator, NSPIIw sheet pile, soils at T2, T3 abutment of Dong Quang Bridge (Ba Vi, Hanoi) and identified the reasonable value of the two specifications of vibrator which is the driving frequency (f) and the weight of supenssion housing (m1), the specific results are shown in table 3.5 Table 3.5 The result of driving frequency (f) and reasonable frame weight (m1) of vibrator Name of soil type The small sand layer of dark gray, medium-tight Middle gravel sand mixed with clay, tight to medium Brown gray clay layer, semi-hard state Suspension mass m1 = 10001100 kg m1 = 1350 kg m1 = 14001500 kg Driving frequency f = 32,2634,19 Hz f = 42,48 Hz f = 20,1920,85 Hz 15 The reasonableness of the calculation results has been verified because when VHQTUTC70 vibrator operates with the set of reasonable parameters (f, m1) which has been found in the above mention, the pilling velocity is the fastest (the pile driving time is minimum) and dynamic resistance acting on sheet pile is also of the smallest value CHAPTER EXPERIMENTAL STUDYING OF SHEET PILE DRIVING PROCESS IN DONG QUANG BRIDGE BY VIBRATOR MANUFACTURED BY VIETNAM 4.1 Purpose, objects and experimental parameters need to be determined 4.1.1 Purpose of experimental research - Determine the dynamic resistances of soisl according to the position of sheet pile when driving by vibrator through measuring the deformation of sheet pile with specific penetration depth values, based on determining the dynamic resistance of each soil layer acting on the sheet pile - Determine the dynamic parameters of the "vibrator - sheet pile-ground" in the actual driving process - Determining the fluidized coefficient (clay), liquefied coefficient (sandy) for the theory of calculating the dynamic resistance of soils acting on sheet pile at experimental locations 4.1.2 Subjects of experimental research - Liebherr HS833HD base cranes; - VH-QTUTC70 vibrator; - NSP-IIw sheet pile; - Geological condition at position T2, T3 Figure 4.3 Diagram of parameters to abutment of Dong Quang Bridge (Ba Vi, Hanoi) be determined during the experiment 4.1.3 Determine the experimental measured parameters: Experimental parameters to be determined are shown in the diagram in figure 4.3 4.2 Building experimental model The experimental model shows the overall diagram of the experimental process and the layout of the measuring heads as shown in figure 4.6 4.3 Building measurement methods - Measure dynamic resistances through stress measurement of sheet pile z ) - Measure the displacement of sheet pile z ) with a long-displacement meter Rotary encoder HE40B-6-1024-3-T-24, by measuring the long-distance movement of z ) the cable (displacement of sheet pile ) - Measure the number of vibrating shaft rotation by lightning frequency probe DT- Figure 4.6 Experimental model of the process of sheet pile driving by vibrator into laminated soil 5TRX-RMTR - Measure the oscillation acceleration of the system by piezoelectric accelerometers direct measurement results Rotations per minute of eccentric shaft Penetration depth of pile Acceleration of the vibratory driven sheet-pile Driving frequency Rate of penetration Velocity of the vibratory driven sheet-pile Acceleration of the suspension housing Deformation of steel sheet piles Velocity of the suspension housing Stresses at sections on steel sheet piles Internal forces at sections on steel sheet piles Displacement Displacement of the of the suspension vibratory housing driven sheet-pile Soil dynamic resistances acting on sheet pile Liquefaction coefficient and fluidized coefficient of soils Indirect measurement results 11 10 13 Excitor block m2 Pkt Clamp mc d1( 2, d2( t2 2, di( ti d1 Rs1 d2 Rs2 Layer Layer Rsi 2, Pile accelerometer 2, 6, 7, 8, Pile strain gauges Length marks on pile Backup pile strain gauge Backup pile accelerometer 10 Guide pulley 11 Pulley measuring penetration depth of the sheet-pile 12 Transducer measuring penetration depth of the sheet-pile 13 Suspension housing accelerometer h1 m1 di Rti Layer i hi Suspension housing h2 P0 Dynamic mass, md = m2 + mc Mass of vibrator, mb = m1+m2 Mass of total system, mtong = m1 + m2 +mc 12 16 1300 500 800 4.4 Manufacturing tested sheet pile Based on the geological structure at the experimental location (T2, T3 abutment of Dong Quang Bridge), the thesis conducted fabrication of experimented steel pile as shown in figure 4.19 4.5 Calibration of measuring equipment Before experimenting, all gauges and measuring devices must be calibrated by licensed competent unit 4.6 Field measurement - The integrating principle diagram of the entire probe with measuring device is shown in figure 4.22 - Diagram of connection of measuring head and measuring device are shown in figure 4.23 2 3 22 11 3 10 11 14500 12 4 4 5000 Experimental sheet pile Connection box Protective panels Right - flange strain gauges Pile accelerometer Web strain gauges Left - flange strain gauges Pile accelerometer of PDA Deformation transducer of PDA 10 Protective panels 11 Signal wire 12 Length marks on pile 2500 5 6 300 6 Figure 4.19 Structure diagram of experimental sheet pile 12 13 Signal converter system 14 15 Data reading device Rotations per minute of eccentric shaft transducer Vibration measuring device VM5112/3 Penetration measuring device CñA CäC PDA device Pile accelerometer Total dynamic resistance acting on sheet pile Deformation transducer of PDA device PDA device Accelerometer of Suspension housing accelerometer Accelerometer of Pile accelerometer Total signal connection box Signal converter system computer deformation measuring device SDA 830B VM 5112/3 Strain Strain gauge at gauge at the section the section 4-4 1-1 VM 5112/3 Accelerometer of Strain gauge at the section 5-5 Penetration depth of pile Strain gauge at the section 6-6 Stress at the section 1-1 Rotations per minute transducer Penetration depth of pile device HE40B -6-1024-3-T-24 Crane Hydraulic oil pipe Cable Pulley Cable measured pile penetration depth Hook Suspension housing Excitor bock Rotations per minute of eccentric shaft transducer 10 Clamp 11 Accelerometer and deformation transducer of PDA 12 Accelerometer of VM5112-3 13 Strain gauges of SDA830B 10 14 Signal wire 11 15 Pile penetration denth transducer Rotations per minute of eccentric shaft Stress at the section 4-4 Stress at the section 5-5 Stress at the section 6-6 SDA830B device Signal converter system Data reading device Electric signal integrator Signal converter system PDA device (Prophylactic) VM5112/3 device ống bảo vệ dây dẫn tín hiệu từ đầu đo nhánh computer Figure 4.22 General diagram of experimental process at construction site Figure 4.23 Diagram of connection of measuring head and measuring device 4.7 Some experimental results - Graph of pile driving Velocity and displacement of sheet pile: Figure 4.36 Velocity of sheet pile (5 times, T3 abutment) Figure 4.37 Displacement of the sheet pile at z = 250 to 280 mm (1st time, f = 15 Hz, T2 abutment) Figure 4.44 Displacement of sheet pile at z = 250 to 280 mm (1st time, f = 35 Hz, T2 abutment) Figure 4.45 Displacement of the sheet pile at z = 10,980 to 10,990m (1st time, f = 35 Hz, T2 abutment) - Acceleration, velocity and experimental displacement of pile (green) and suspension housing (red): 17 - Experimental dynamic resistances of soils on sheet pile: Figure 4.52 The toe resistance (f = 35 Hz, T2 abutment) (Figure 4.53 The toe resistance from to seconds (f = 35 Hz, T2 abutment) Figure 4.55 Dynamic shaft resistance (f = 35 Hz, T2 abutment) 4.56 Dynamic shaft resistance from to 2s (f = 35 Hz, T2 abutment) Figure 4.54 The toe resistance is from 80 to 81s (f = 35 Hz, T2 abutment) Figure 4.57 Dynamic shaft resistance from 80 to 81s (f = 35 Hz, T2 abutment) - Calculation result of liquefied coefficient and fluidized coefficient: Table 4.23 Liquefied and fluidized coefficient of soils at T2 abutment Soil layer (particles small, medium tight sand) TT Frequency, Hz 15 20 25 30 35 Toe liquefied coefficient Shaft pile liquified coefficient 0,43601 0,38189 0,29204 0,26565 0,16629 0,16808 0,16729 0,11057 0,10853 0,09307 Soil layer (clay phase, half hard) Shaft pile Toe fluidized fluidized coefficient coefficient of shaft pile 0,33991 0,15663 0,35762 0,09306 0,46179 0,12552 0,34566 0,14052 0,15115 0,14578 Note TT Frequency, Hz Table 4.24 Liquefied and fluidized coefficient of soils at T3 abutment 15 20 25 30 35 Soil layer (particle sand small, discrete) Toe liquefied coefficient 0,6478 0,5658 0,7772 0,5339 0,2316 Shaft pile liquified coefficient 0,1448 0,1329 0,1091 0,1073 0,1041 Soil layer (medium grain sand, gravel, medium tight) Toe liquefied coefficient 0,1908 0,1787 0,2471 0,2432 0,1157 Shaft pile liquified coefficient 0,1520 0,1664 0,1174 0,1091 0,1159 Soil layer (mixed clay, half hard to firm) Toe liquefied coefficient 0,6683 0,8657 0,3700 0,1729 0,1810 Ghi Shaft pile liquified coefficient 0,2071 0,1107 0,1268 0,1394 0,1761 4.9 Comparation for evaluation between theoretical and experimental results To verify between the results of theoretical calculations and empirical research results, the thesis uses the results of theoretical calculations (Chapter 2) and experimental 18 results (Chapter 4) with specific cases (NSP-IIw sheet pile, VH-QTUTC70 vibrator, laminated soil at T2 abutment of Dong Quang Bridge) for comparison and evaluation b) The theoretical shift of the pile (z=2m) c) Experimental displacement of the pile (z=2m) Figure 4.58 Displacement of pile (T2 abutment, f = 30Hz) Figure 4.59 Acceleration of pile (T2 abutment, f = 30Hz) Figure 4.61 Velocity of pile (T2 abutment, f = 30Hz) Figure 4.63 Displacement of pile (T2 abutment, f = 30Hz) a) Dynamic shaft resistance b) Dynamic shaft resistance at t = s (layer 1) c) Dynamic shaft resistance at t=80s (layer 2) Figure 4.65 Displacement of pile ( T2 abutment, f=30Hz) a) Dynamic toe resistance b) Dynamic toe resistance at t = s (layer 1) a) Dynamic toe resistance at t = s (layer 2) Figure 4.66 Dynamic toe resistance (T2 abutment, f = 30Hz) - Differency between the result of theoretical and experimental displacement of the pile: Table 4.25 Differency between theoretical and experimental displacement Time, s Theoretical penetration, m Experimental penetration, m Differency 10 20 30 40 50 60 70 80 1,65 1,450 3,149 2,806 4,801 4,192 6,310 5,557 7,416 6,898 8,474 8,217 9,510 9,516 10,289 10,797 12% 11% 13% 12% 7% 3% 0% -5% - Differency between the results of acceleration of theoretical and real oscillations of pile Table 4.26 Differencys between theoretical and experimental oscillations Time, s Theoretical acceleration, m/s2 Experimental acceleration, m/s2 Differency 10 20 30 40 50 60 70 80 199,38 214,80 199,67 201,25 206,45 196,23 207,46 211,07 178,32 188,82 173,96 188,56 209,26 206,31 181,23 195,78 11% 12% 13% 6% -1% -5% 13% 7% - Differency between the results of theoretical and actual oscillation velocity of the pile: Table 4.27 Differencys between theoretical and experimental oscillations Time, s Theoretical velocity, m/s Experimental velocity, m/s Differency 10 0,875 0,861 2% 20 0,938 0,908 3% 30 0,820 0,831 -1% 40 0,718 0,800 -11% 50 0,820 0,716 13% 60 0,795 0,696 12% 70 0,786 0,687 13% - Differency between the results of theoretical and actual displacement of pile 80 0,731 0,547 13% 19 Table 4.28 Differencys between theoretical and experimental displacements Time, s Theoretical displacement, mm Experimental displacement, mm Differency 10 3,108 3,390 -9% 20 2,967 3,198 -8% 30 2,924 3,017 -3% 40 3,378 2,925 13% 50 2,566 2,385 7% 60 2,208 1,934 12% 70 1,898 1,708 10% 80 1,356 1,314 3% - Differency between dynamic resistance results of theoretical and practical shaft pile: Table 4.29 Differencys between dynamic forces into theoretical and experimental pile Time, s Theoretical dynamic shaft resistance, kN Experimental dynamic shaft resistance, kN Differency 30 40 50 60 70 80 261,69 228,31 338,70 298,15 396,72 347,15 429,24 383,63 466,57 412,04 478,57 492,94 13% 12% 12% 11% 12% -3% - Differency between the results of theoretical and practical force of toe Table 4.30 Differency between theoretical and experimental toe force Time, s Theoretical dynamic toe resistance, kN Experimental dynamic toe resistance, kN Differency 30 17,13 14,90 13% 40 26,84 23,42 13% 50 26,84 23,45 13% 60 26,84 23,48 13% 70 26,84 23,56 12% 80 26,84 23,60 12% CONCLUSION CHAPTER By experiment, it has measured the dynamic resistances of soil layers acting on sheet pile when driving pile, thereby determining the liquefied coefficient and the fluidized coefficient these soil layers, complete the input data for "Vibrator - sheet pile - laminated soil " in Chapter (tables 4.23 to 4.24) Determined the acceleration, velocity and displacement of the elements of "Vibrator sheet pile - laminated soil" in actual working process corresponding to the frequency values of vibrator (Tables 4.9 to 4.13, Appendix C.3) Determination of sheet pile velocity (table 4.19, 4.20; figure from 4.32 to 4.36 and Appendix C.3) Evaluated the reliability of the theoretical model and calculation program that the thesis has built in Chapter and Chapter by comparing the results of theoretical calculations with experimental results, specifically shows: - The result compare theoretical and experimental dynamics with differency of less than 15%, thus it can confirm that the correctness of the theoretical model and calculation program developed in Chapter - The result compare theory and experimental dynamic resistances with the differency of less than 15%, thereby the model and theory of computating dynamic resistances for sandy soils and clay soils, which has selected in Chapter is correct CONCLUSIONS AND RECOMMENDATIONS CONCLUSION Through the research results, some conclusions are given by the thesis as follows: Based on the research method of "Vibrator - sheet pile - laminated soil ", the thesis has built a dynamic model, an algorithm diagram; selected the soil model and mathematical for determination of the dynamic resistances of soil on sheet pile for sandy soils and clay soils and built a calculation program on Matlab software as shown in Appendix A.1 Applied the calculation program for the specific case of VH-QTUTC70 vibrator, Ushaped sheet pile (NSP-IIw type) and laminated soil at T2 and T3 abutment of Dong Quang Bridge (Ba Vi, Ha Noi), on the basis of using liquefied coefficient and fluidized coefficient of soils (determined experimentally in Chapter 4), the obtained results show 20 similarities between the theoretical calculation results and experimental results with differency of less than 15% A method has been developed to determine the reasonable parameters of vibrator when driving sheet pile into laminated soil, including defining the objective function according to the smallest specific energy cost, building an algorithm diagram and develop a calculation program on Matlab software as shown in Appendix A.2 Applied calculation program for specific case, thereby determining the fair value of two typical parameters (f and m1) of VH-QTUTC70 vibrator when driving NSP-IIw sheet pile in some types of soil at T2 and T3 abutment of Dong Quang Bridge (Ba Vi, Hanoi) The results are summarized as follows: Soil type The small sand layer of dark gray, medium-tight Middle gravel sand mixed with clay, tight to medium Brown gray clay layer, semi-hard state Suspension mass m1 = 10001100 kg Driving frequency f = 32,2634,19 Hz m1 = 1350 kg f = 42,48 Hz m1 = 14001500 kg f = 20,1920,85 Hz By experimental research, the liquefied coefficient and fluidized coefficient of some types of soil at T2 and T3 abutment of Dong Quang Bridge (Ba Vi, Hanoi) were determined according to frequency with specific case which is VH-QTUTC70 vibrator and NSP-IIw sheet pile Specific result of these experimental factors are shown in Appendix C.2 and summarized in the following table: Frequency (f) Soil type Experimental coefficients The small and discrete black gray granular sand liquefied coefficient Medium grain The sand mixed with gravel, medium tight and tight liquefied coefficient Brown-gray clay layer, semi-hard state Fluidized coefficient Pile toe Pile shaft Pile toe Pile shaft Pile toe Pile shaft 15 Hz 20 Hz 25 Hz 30 Hz 35 Hz 0,436 0,648 0,145 0,168 0,191 0,382 0,566 0,133 0,167 0,179 0,292 0,777 0,109 0,111 0,247 0,266 0,534 0,107 0,109 0,243 0,167 0,232 0,093 0,104 0,116 0,152 0,166 0,117 0,109 0,116 0,334 0,668 0,157 0,207 0,358 0,866 0,093 0,111 0,370 0,462 0,126 0,127 0,173 0,346 0,139 0,141 0,151 0, 181 0,146 0,176 RECOMMENDATIONS AND FURTHER RESEARCH DIRECTIONS Applying the reseach results to determine reasonable technical parameters of vibrator in order to optimize the structure and shape of vibrators manufactured in the country Studying the application of these reseach results and developing the program to determine reasonable parameters of vibrator to control vibrator flexibly sensing to load by changing the driving frequency and weight of supenssion housing (increasing weight with free-hanging systems or forcing with Leader-mounted systems) according to the total resistance of soil Developing the research direction of the thesis towards flexible adjustment of eccentric torque parameters of vibrator during the working process by changing the number of pairs of eccentric wheels involved in the process of creating driving force of vibrator which allow to control vibrator more flexible (independent frequency control with driving force value control), so the vibrator efficiency will increase and promote program for optimal calculation according to genetic algorithms 21 Developing the thesis's research direction in the direction of applying simulation theory and finite element theory to build a calculation program, simulating the process of driving steel pile into laminated soil by vibrator (driving force) [55], [54], [7], [32], [33], [35], [36], [3], [4], [38], [39], [6], [41], [42], [45], [9], [50], [11], [52], [53], [13], [15], [17], [18], [21], [57], [60], [61], [63], [64], [26], [28], [25], [24], [66], [67], [47], [48], [69], [72], [71], [30], [76], [68], [46], [58], [43], [8], [56], [29], [70], [37], [10], [40], [65], [75], [5], [20], [27], [14], [34], [49], [59], [12], [22], [23], [62], [51], [74],[19], [31], [73], [2], [1], [16] ... of Hanoi and Thanh Thuy District of Phu Tho Province Process: Km0 - Km2+196,11 Project: Investment and construction of Dong Quang bridge Location: Ba Vi District of Hanoi and Thanh Thuy District... pile The mass of sheet pile Mass of 1m long sheet pile Inertia moment of pile sheet Symbol At lcọc mc gcvt Jcvt Value 1,5 1,04E-02 14,5 1183,2 81,6 5,22E-05 Unit m m2 m kg kg/m m4 - Parameters... pile - laminated soil" When the vibrator acting, a part of the energy of the vibrator is transmitted to soil, stimulating the vibrating soil particles to create a liquid state (sand) and a fluidized
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