CECW-EG Engineer Manual 1110-2-1901 Department of the Army U.S. Army Corps of Engineers Washington, DC 20314-1000 EM 1110-2-1901 30 September 1986 (original) 30 April 1993 (change 1) Engineering and Design SEEPAGE ANALYSIS AND CONTROL FOR DAMS Distribution Restriction Statement Approved for public release; distribution is unlimited. CECW-EG-S Engineer Manual No. 111 O-2-1 901 DEPARTMENT OF THE ARMY U.S. Army Corps of Engineers Washington, DC 20314-1000 EM 1110-2-l 901 Change 1 30 April 1993 Engineering and Design SEEPAGE ANALYSIS AND CONTROL FOR DAMS 1. This change replaces Appendix D, “Filter and Drain Design and Construction” of EM 1110-2-1901, dated 30 September 1986. 2. File this change sheet in front of the publication for reference purposes. FOR THE COMMANDER: WILLIAM D. BROWN Colonel, Corps of Engineers Chief of Staff ENGINEER MANUAL EM 1110-2-1901 30 September 1986 ENGINEERING AND DESIGN SEEPAGE ANALYSIS AND CONTROL FOR DAMS DEPARTMENT OF THE ARMY CORPS OF ENGINEERS OFFICE OF THE CHIEF OF ENGINEERS DAEN-ECE-G Engineer Manual No. 1110-2-1901 30 September 1986 Engineering and Design SEEPAGE ANALYSIS AND CONTROL FOR DAMS 1. Purpose. This manual presents the fundamental design principles and guidance concerning seepage considerations for design of new dams and the evaluation of existing projects. 2. Applicability. This manual is applicable to all HQUSACE/OCE elements and field operating activities having responsibility for the design and construction of civil works projects. 3. Discussion. All earth and rock-fill dams are subject to seepage through the embankment, foundation, and abutments. Concrete gravity and arch dams are subject to seepage through the foundation and abutments. Seepage control is necessary to prevent excessive uplift pressures, sloughing of the downstream slope, piping through the embankment and foundation, and erosion of material by loss into open joints in the foundation and abutments. The purpose of the project, i.e., long-term storage, flood control, etc., may impose limitations on the allowable quantity of seepage. FOR THE COMMANDER: Chief of Staff This manual supersedes EM 1110-2-1901 dated February 1952 DEPARTMENT OF THE ARMY US Army Corps of Engineers Washington, D. C. 20314-1000 EM-1110-2-1901 30 September 1986 DAEN-ECE-G Engineer Manual No. 1110-2-1901 Engineering and Design SEEPAGE ANALYSIS AND CONTROL FOR DAMS Table of Contents Page ParagraphSubject CHAPTER 1. INTRODUCTION Purpose Applicability References Objective and Scope General Considerations 1-1 1-2 1-3 1-4 1-5 1-1 1-1 1-1 1-1 1-1 CHAPTER 2. DETERMINATION OF PERMEABILITY OF SOIL AND CHEMICAL COMPOSITION OF WATER Darcy's Law Range of Validity of Darcy's Law Coefficient of Permeability Factors Influencing Permeability Indirect Methods for Determining Permeability Laboratory Methods for Determining Permeability Origin, Occurrence, and Movement of Ground Water Field Methods for Determining permeability Chemical Composition of Ground Water and River (or Reservoir) Water 2-1 2-1 2-2 2-4 2-3 2-6 2-4 2-9 2-5 2-20 2-6 2-28 2-7 2-30 2-8 2-33 2-9 2-34 CHAPTER 3. DETERMINATION OF PERMEABILITY OF ROCK Permeabilities of Rock Masses Flow Characteristics in Rock Masses Methods for Determining Rock Mass Permeability Applications of Rock Mass Permeability 3-1 3-1 3-2 3-1 3-3 3-4 3-3 3-11 This manual supersedes EM 1110-2-1901, Feb 52 i EM 1110-2-1901 30 Sep 86 Subject Paragraph Page CHAPTER 4. SEEPAGE PRINCIPLES General Considerations Boundary Conditions Confined and Unconfined Flow Problems Laplace’s Equation Methods for Solution of Laplace's Equation Graphical Method for Flow Net Construction Flow Net for Anisotropic Soil Flow Net for Composite Sections Determination of Seepage Quantities, Escape Gradients, Seepage Forces, and Uplift Pressures 4-1 4-1 4-2 4-1 4-3 4-2 4-4 4-3 4-5 4-6 4-7 4-8 4-5 4-9 4-14 4-14 4-9 4-21 CHAPTER 5. CONFINED FLOW PROBLEMS General Considerations Gravity Dam on Pervious Foundation of Finite Depth Gravity Dams on Infinitely Deep Pervious Foundations 5-1 5-1 5-2 5-1 5-3 5-1 CHAPTER 6. UNCONFINED FLOW PROBLEMS Introduction Homogeneous Earth Dam on Impervious Foundation Earth Dam with Horizontal Drain on Impervious Foundation Earth Dam with Toe Drain on Impervious Foundation Earth Dam with Vertical or near Vertical Horizontal Drains on Impervious Foundation Flow Net for a Composite Zoned Dam Zoned Earth Dam on Pervious Foundation 6-1 6-1 6-2 6-1 6-3 6-10 6-4 6-10 6-5 6-10 6-6 6-10 6-7 6-17 CHAPTER 7. SEEPAGE TOWARD WELLS Use of Wells Analysis of Well Problems Basic Well Equations for Steady State Flow Special Conditions Nonsteady State Flow 7-1 7-1 7-2 7-1 7-3 7-2 7-4 7-11 7-5 7-21 ii EM 1110-2-1901 30 Sep 86 Subject Paragraph Page CHAPTER 8. SEEPAGE CONTROL IN EMBANKMENTS CHAPTER 9. SEEPAGE CONTROL IN EARTH FOUNDATIONS CHAPTER 10. CHAPTER 11. CHAPTER 12. REMEDIAL SEEPAGE CONTROL General Methods for Seepage Control Flat Slopes Without Drains Zoning Embankments Vertical (or Inclined) and Horizontal Drains Seepage Control Against Earthquake 8-1 8-2 8-3 8-4 8-5 8-6 8-1 8-1 8-1 8-1 Effects 8-8 8-18 General Selection of Method for Seepage 9-1 9-2 9-3 9-4 9-5 9-6 9-7 9-8 9-9 9-1 Control Horizontal Drains Cutoffs Upstream Impervious Blanket Downstream Seepage Berms Relief Wells Trench Drain Concrete Galleries 9-1 9-1 9-1 9-48 9-58 9-62 9-83 9-84 SEEPAGE CONTROL THROUGH EARTH ABUTMENTS ADJACENT TO STRUCTURES AND BENEATH SPILLWAYS AND STILLING BASINS Through Earth Abutments Adjacent to Outlet Conduits Beneath Spillways and Stilling Basins 10-1 10-2 10-3 10-1 10-1 10-3 SEEPAGE CONTROL IN ROCK FOUNDATIONS AND ABUTMENTS General Considerations Cutoff Trenches Abutment Impervious Blankets Drainage and Grouting Galleries and Tunnels Grouting of Foundations and Abutments Surface Treatment of Foundations and Abutments 11-1 11-2 11-3 11-1 11-1 11-2 11-4 11-5 11-2 11-3 11-6 11-3 General Considerations 12-1 12-1 Remedial Methods 12-2 12-1 Storage Restriction 12-3 12-2 Grouting 12-4 12-2 iii EM 1110-2-1901 30 Sep 86 Subject CHAPTER 13. CHAPTER 14. APPENDIX A. APPENDIX B. APPENDIX C. Upstream Impervious Blanket 12-5 Downstream Berm 12-6 Slurry Trench Cutoff 12-7 Relief Wells 12-8 Drainage of Downstream Slope 12-9 Page 12-4 12-6 12-6 12-11 12-12 MONITORING PERFORMANCE OF SEEPAGE CONTROL MEASURES General Considerations 13-1 13-1 Piezometers for Seepage Pressures 13-2 13-1 Flow Measurements 13-3 13-12 Seepage Water Analysis 13-4 13-18 Remote Sensing Methods 13-5 13-20 INSPECTION, MAINTENANCE, AND REHABILITA- TION OF SEEPAGE CONTROL MEASURES Introduction 14-1 14-1 Inspection 14-2 14-1 Maintenance 14-3 14-1 Rehabilitation 14-4 14-3 REFERENCES Government Publications Non-Government Publications APPROXIMATE METHODS FOR ANALYSIS OF FLOW PROBLEMS A-1 A-11 Introduction Electrical Analogy Sand Tank Model Viscous Flow Models Method of Fragments Finite Difference Method Finite Element Method B-1 B-1 B-2 B-1 B-3 B-2 B-4 B-5 B-5 B-5 B-6 B-28 B-7 B-29 ANALYSIS OF PRESSURE INJECTION TESTS (Ziegler 1976) Water pressure Tests Air pressure Tests pressure Holding Testy C-1 C-2 C-3 C-1 C-11 C-17 Paragraph iv EM 1110-2-1901 30 Sep 86 Subject Paragraph Page APPENDIX D. FILTER AND DRAIN DESIGN AND CONSTRUCTION General Stability Permeability Applicability Perforated Pipe Gap-Graded Base Gap-Graded Filter Broadly-Graded Base Graded Filter Design Geotextiles Construction Monitoring D-1 D-2 D-3 D-4 D-5 D-6 D-7 D-8 D-9 D-10 D-11 D-12 D-1 D-1 D-2 D-2 D-3 D-3 D-5 D-5 D-5 D-6 D-6 D-8 v EM 1110-2-1901 30 Sep 86 CHAPTER 1 INTRODUCTION 1-1. Purpose. This manual provides guidance and information concerning seep- age analysis and control for dams. 1-2. Applicability. The provisions of this manual are applicable to all HQUSACE/OCE elements and field operating activities (FOA) having responsibil- ity for seepage analysis and control for dams. 1-3 References. Appendix A contains a list of Government and non-Government references pertaining to this manual. Each reference is identified in the text by either the designated publication number or by author and date. Reference to cited material in tables and figures is identified throughout the manual by superscripted numbers (item 1, 2, etc.) that correspond to similarly numbered items in Appendix A. 1-4. Objective and Scope. The objective of this manual is to provide a guide for seepage analysis and control for dams. 1-5. General Considerations. All earth and rock-fill dams are subject to seepage through the embankment, foundation, and abutments. Concrete gravity and arch dams are subject to seepage through the foundation and abutments. Seepage control is necessary to prevent excessive uplift pressures, sloughing of the downstream slope, piping through the embankment and foundation, and erosion of material by loss into open joints in the foundation and abutments. The purpose of the project, i.e., long-term storage, flood control, etc., may impose limitations on the allowable quantity of seepage (Sowers 1977). 1-1 [...]... permeability of the soil, particularly for cohesive soils (Quirk and Schofield 1955 and Cary, Walter, and Harstad 1943) Available data indicate that cohesive soils may be two to three orders of magnitude more permeable to seepage water containing moderate amounts of dissolved salts (less than 300 parts per million by weight) than the distilled water (Carry, Walter, and Harstad 1943) d Degree of Saturation... degree of saturation is greater than 85 percent, most of air present in the soil is in the form of small occluded bubbles and Darcy's law will be approximately valid The ratio of the permeability of the unsaturated sand to the saturated sand at the same void ratio is given as (Scott 1963 and Parker and Thornton 1976) ( 2-1 5) where k us = unsaturated permeability m = constant with values between 2 (uniform... clay particles (dimension not shown in length) Permeability versus void ratio for various clay minerals Figure 2-9 Influence of particle size and void ratio on 294 permeability of clay minerals (courtesy of Macmillan ) 2-1 6 EM 111 0-2 -1 901 30 Sep 86 Table 2-2 Coefficients of Permeability for Different Exchange Cations and Void Ratios for Two Clay Mineralsa Permeabilities are obtained by falling-head test... permeability of uniform fine sand (from Fenn171) Figure 2-1 2 Influence of type and amount of fines on permeability of concrete sand, sand-gravel mixture, and uniform fine sand (prepared by WES) 2-2 2 EM 111 0-2 -1 901 30 Sep 86 b Masch and Denny Method For uniform or nonuniform dense clean sands, classified SP or SW in the Unified Soil Classification System (U S Army Engineer Waterways Experiment Station... fraction of the material was almost completely absent along the banks of the river and noted that the ground-water table was level for several hundred feet away from the river and fluctuated rapidly with changes in river stage Field pumping tests were conducted which indicated somewhat variable permeabilities but none approaching the magnitude of openwork gravels Based upon the available data, the dam... clay mineral size and increase in void ratio (ratio of the volume of voids to the volume of solid particles in the soil mass) as shown in figure 2-9 (Yong and Warkentin 1966).(l) For cohesionless soils, the size and shape of the soil particles influence the permeability Allan Hazan conducted tests on filter sands for use in waterworks and found that for uniform loose clean sands the permeability was... rate of discharge for a gradient of unity through a vertical strip of aquifer one unit wide and has dimensions of length squared per unit time and is usually expressed in square feet per day 2-4 Factors Influencing Permeability a Range of Values of Permeability No other property of soil exhibits a wider range of values (up to ten orders of magnitude) or shows greater directional (anisotropy) and spatial... gradients indicate turbulent flow Darcy's law for a fine sand, as shown in figure 2-8 , is valid only for the hydraulic gradient less than 2 for the loose state and 4.5 for the dense state For soils larger than a fine sand, Darcy's law is valid for progressively smaller hydraulic gradients (Burmister 1948 and Burmister 1955) f Particle Size For cohesive soils, the permeability increases with increases... that this occurs because of the parallel arrangement of clay platelets in the wetter material after compaction a Courtesy of Addison-Wesley Publishing Company, Inc 2-1 7 251 EM 111 0-2 -1 901 30 Sep 86 g Particle Shape and Surface Roughness Cohesionless soil particles have different particle shapes and surface roughness dependent on the distance they have been transported by flowing water from the place... an order of magnitude decrease in permeability (Barber and Sawyer 1952) The addition of 4.2 percent silt fines to sand-gravel mixture decreases the permeability two orders of magnitude Similar results are obtained by the addition of 2-1 8 EM 111 0-2 -1 901 30 Sep 86 2-1 9 EN 111 0-2 -1 901 30 Sep 86 Figure 2-1 0 Krumbein and Sloss standard chart for visual estimation of sphericity and roundness of cohesionless . 9-1 9-1 9-1 9-4 8 9-5 8 9-6 2 9-8 3 9-8 4 SEEPAGE CONTROL THROUGH EARTH ABUTMENTS ADJACENT TO STRUCTURES AND BENEATH SPILLWAYS AND STILLING BASINS Through Earth Abutments Adjacent to Outlet Conduits Beneath Spillways and Stilling. B-1 B-1 B-2 B-1 B-3 B-2 B-4 B-5 B-5 B-5 B-6 B-28 B-7 B-29 ANALYSIS OF PRESSURE INJECTION TESTS (Ziegler 1976) Water pressure Tests Air pressure Tests pressure Holding Testy C-1 C-2 C-3 C-1 C-11 C-17 Paragraph iv EM. rock-fill dams are subject to seepage through the embankment, foundation, and abutments. Concrete gravity and arch dams are subject to seepage through the foundation and abutments. Seepage control