IH-635 MANAGED LANES PROJECT GEOTECHNICAL INTERPRETIVE REPORT FOR THE REFERENCE SCHEMATIC - SEGMENT A prepared for: Texas Department of Transportation Dallas District Office prepared by: Lachel Felice & Associates, Inc. Dallas, Texas JUNE 2006 TABLE OF CONTENTS TABLE OF CONTENTS............................................................................................. ii LIST OF TABLES ...................................................................................................... v LIST OF FIGURES ................................................................................................... vi 1.0 INTRODUCTION ...............................................................................................1 1.1 Project Overview ............................................................................................ 1 1.2 Purpose and Scope........................................................................................ 1 1.3 Sources of Information ................................................................................... 1 1.3.1 General....................................................................................................1 1.3.2 Site Specific Investigations and Reports .................................................2 1.4 Limitations and Disclaimer ............................................................................. 4 2.0 PROJECT SETTING .........................................................................................6 2.1 General........................................................................................................... 6 2.2 Segment A Configuration ............................................................................... 6 2.3 Physiography and Regional Geology............................................................. 7 2.4 Stratigraphy.................................................................................................... 7 2.4.1 Overburden..............................................................................................7 2.4.2 Bedrock....................................................................................................9 2.5 Geologic Structure........................................................................................ 10 2.6 Groundwater Conditions from a Regional Geologic Perspective ................. 11 2.7 Regional Seismicity...................................................................................... 11 3.0 GROUND CHARACTERIZATION AND SITE CONDITIONS ..........................13 3.1 Engineering Properties of Soil and Rock...................................................... 13 3.1.1 Overburden Soils...................................................................................13 3.1.2 Bedrock..................................................................................................17 3.2 Hydrogeologic Setting .................................................................................. 26 3.2.1 Hydraulic Conductivity ...........................................................................26 3.2.2 Groundwater Elevations ........................................................................27 3.3 In Situ Stress Conditions.............................................................................. 30 3.4 Environmental Considerations ..................................................................... 30 3.5 Geologic Conditions along Segment A......................................................... 30 3.5.1 Station 67+00 to 92+00 (Josey Lane to Webb Chapel Road) ...............31 3.5.2 Station 92+00 to 130+00 (Webb Chapel to 1,800 ft West of Marsh Lane) .....................................................................................................32 3.5.3 Station 130+00 to 163+00 (1,800 ft West of Marsh Lane to 1,500 ft East of Marsh Lane) ..............................................................................32 3.5.4 Station 163+00 to 191+00/195+00 (1,500 ft East of Marsh Lane to West Mined Tunnel Portals) ..................................................................33 3.5.5 West Mined Tunnel Portals to Station 264+00 (Mined Tunnel) .............34 3.5.6 Station 264+00 to 305+00 (Mined Tunnel) ............................................35 3.5.7 Station 305+00 to 334+00 (Mined Tunnels to East Mined Tunnel Portals) ..................................................................................................35 3.5.8 Station 334+00 to 356+00 (East Mined Tunnel Portals to 700 ft West of Hillcrest Road)..........................................................................36 3.5.9 Station 356+00 to 360+00 (End Below Grade Sections to West of Hillcrest Road) .......................................................................................36 4.0 PREVIOUS CONSTRUCTION EXPERIENCE ................................................37 4.1 General......................................................................................................... 37 4.2 Mined Tunnels in Austin Chalk..................................................................... 37 4.3 Vertical Cuts in Austin Chalk........................................................................ 37 ii 4.3.1 DART Mockingbird Station ....................................................................37 4.3.2 Addison Airport Toll Tunnel ...................................................................38 4.4 Vertical Cuts in Eagle Ford Shale ................................................................ 39 4.4.1 President George Bush Turnpike, Carrollton Section............................39 4.4.2 President George Bush Turnpike, Las Colinas Section.........................40 4.4.3 One Main Place, Downtown Dallas .......................................................40 4.4.4 I-30 Widening, Dallas, Loop 12 to Sylvan..............................................40 4.4.5 Landfill Case History, Slope Failure.......................................................41 4.4.6 DFW Airport, Slope Failure During Construction of Utility Corridor .......41 5.0 DESIGN CONSIDERATIONS FOR MINED TUNNELS...................................42 5.1 General......................................................................................................... 42 5.2 Ground Response ........................................................................................ 42 5.3 Initial Ground Support .................................................................................. 43 5.3.1 Mined Tunnels and Associated Underground Structures ......................43 5.3.2 Portal Design .........................................................................................43 5.4 Final Lining Design....................................................................................... 44 5.5 Argillaceous Zones....................................................................................... 44 5.6 Bentonite Seams.......................................................................................... 44 5.7 Groundwater and Seepage Control.............................................................. 45 5.8 Combustible and Toxic Gases ..................................................................... 46 5.9 Corrosion Potential....................................................................................... 46 5.10 Recommended Additional Subsurface Investigations ................................ 46 6.0 DESIGN CONSIDERATIONS FOR CUT-AND-COVER TUNNEL AND U- WALL SECTIONS ...........................................................................................47 6.1 General......................................................................................................... 47 6.2 Long-term Earth Pressure Loading Basis .................................................... 47 6.2.1 At-rest Earth Pressures (Ko) in Clay and Shale .....................................47 6.2.2 Special Considerations Regarding Lateral Swell Pressures due to Swelling Clays and Clay Shales ............................................................48 6.2.3 Methods of Stabilizing Vertical Cuts in Weathered and Fresh Austin Chalk ..........................................................................................49 6.2.4 Groundwater Level at the Ground Surface ............................................50 6.2.5 Surcharge Loads ...................................................................................50 6.3 Vertical Swell Design Considerations........................................................... 50 6.4 Long-term Loading on Walls (by Station) ..................................................... 51 6.4.1 Station 67+00 to Station 92+00 (Josey Lane to Webb Chapel Road).....................................................................................................51 6.4.2 Station 92+00 to Station 130+00 (Webb Chapel to 1,800 ft West of Marsh Lane) ..........................................................................................52 6.4.3 Station 130+00 to Station 163+00 (1,800 ft West of Marsh Lane to 1,500 ft East of Marsh Lane) .................................................................52 6.4.4 Station 163+00 to Station 191+00/195+00 (1,500 ft East of Marsh Lane to West Tunnel Portals) ................................................................53 6.4.5 Station 334+00 to Station 356+00 (East Portals to 700 ft West of Hillcrest Road) .......................................................................................54 6.4.6 Station 356+00 to End Below Grade