Underground Risk Management Course Marina Del Rey, California November, 2018 Geotechnical Data Reports Greg Raines, PE Gregory.Raines@Stantec.com
Introduction What is a Geotechnical Data Report? The GDR is a document developed by the Designer and/or the Designer's geotechnical engineer, which contains the factual information that has been gathered during the exploration and design phases of the Project. The GDR should contain the following information: a description of the geologic setting; a description/discussion of the site exploration program; the logs of all borings, trenches, and other site investigations; a description/discussion of all field and laboratory test programs; and the results of all field and laboratory testing. The GDR should NOT interpret ANY geological or geotechnical data.
Geologic Profile LEGEND
Geologic Profile LEGEND
Introduction Geotechnical Reports Geotechnical Reports Contract Document Non-Contract Document GDR Data Only GBR Interpretive Baseline GDM Interpretive Geotech
Introduction Disclaimers Disclaimers have been used in the past by Owners to broadly disclaim all subsurface information made available to bidders. This practice is in direct conflict with the concept of geotechnical reports. A Contractor has a right to rely on data provided. Any broad, exculpatory language intended to shed responsibility from the Owner would be ignored by the courts. A narrowly worded disclaimer can be used in the GDR to: eliminate unreliable data from further consideration; shed responsibility for the accuracy of subsurface information obtained by third parties for unrelated projects; differentiate conservative design assumptions from best estimate interpretations of subsurface conditions and behavior.
Introduction Geotechnical Data Report 1. Project Overview 2. Area Geology a) Geologic Map b) Seismic setting and regional faults c) Definition of relevant geologic terms 3. Field Investigation a) Boring logs and rock core photos b) Logging procedures c) Drilling procedures d) Groundwater evaluation e) Field testing 4. Laboratory Testing a) Testing standards b) Testing strategy c) Types and number of tests d) Results summary
Introduction Geotechnical Data Report Appendices 1. Geological Reconnaissance and Mapping 2. Boring Log data 3. Field Testing Data 4. Geophysics 5. Groundwater data 6. Laboratory data 7. Historical Data
Geological Reconnaissance and Mapping Appendix - Geological Reconnaissance and Mapping Collect available data Field geologic mapping Structural data collection Kinematic analysis
Geological Reconnaissance and Mapping Identify/Collect Available Geotechnical Data in the Project Area Information can include: Geologic maps Data from previous reports Drill hole data Preliminary mapping Compile available local data into a database for further evaluation.
Geological Reconnaissance and Mapping Field Geologic Mapping
Geological Reconnaissance and Mapping Field Geologic Mapping Structural Data Collection (faults, folds, shears, contacts, alteration zones) Mapping at the scale of the project/features!
Geological Reconnaissance and Mapping Geologic Mapping and Reconnaissance
Geological Reconnaissance and Mapping Geomechanical Mapping of Discontinuities (Kinematic Data Analysis)
Boring Log Data Appendix Boring Log Data Drilling methods Boring log legend, boring logs, and completion logs Sampling methods and equipment (SPTs) Hand held field tests (torvane) Groundwater level measurements Sample handling, CoC
Boring Log Data Types of Rigs Some typical methods to drill the subsurface include: Auger Mud/Air Rotary Mud/Air Rotary with Casing Advance Reverse Circulation Sonic Becker Penetration Large Diameter Cone Penetration Tests (CPT) Rock Core Each of these methods have pros and cons and are well suited for specific exploration programs, depending on both the subsurface conditions as well as the data needs for the program.
Boring Log Data Types of Rigs Auger Pros: Simple, widely available No water, mud, or air Accommodates most sampling types Cons: Depth limitations Gravels, cobbles limitations Flowing/running ground limitations Hole collapse (solid stem)
Boring Log Data Types of Rigs Mud / Air Rotary Pros: Widely available Accommodates most sampling types Efficient in most ground conditions Cons: Location of G.W. in drill hole Mud impact to sensing/testing zone Cobble/boulder limitations
Boring Log Data Types of Rigs Reverse Circulation Schramm (dual tube RC air percussion rig) Pros: Efficient Can identify water zones (air) Large diameter (nested wells) High depth capacity Cons: Logging cuttings Sampling limitations Larger equipment/support requirements
Boring Log Data Types of Rigs Sonic Pros: Efficient No water, mud or air Accommodates most sampling types Nearly full sample recovery Can detect water in recovered core Advance through most geotechnical conditions Cons: Not widely available for investigation purposes Potential for sample disturbance Comparatively slightly higher $/m
Boring Log Data Types of Rigs Large Diameter Borings Physical examination/mapping of the intact geologic conditions
Boring Log Data Cone Penetrometer Testing
Boring Log Data Types of Rigs Rock Core
Boring Log Data Test Pits Used for soil logging, sample collection and lab testing materials anticipated to be encountered.
Boring Log Data Typical Drill Hole Logs General: Drill rate Rig Behavior Circulation return Depth to water Instrumentation Drill difficulties Shift changes Testing intervals and results Soil: Lithology Soil type (USCS) Color Consistency / density Grain size distribution Moisture Cementation Plasticity (clays) Roundness Rocks: Rock Type Recovery, RQD, GSI Color Texture Degree of weathering Strength Hardness Structure Discontinuities: Type Width Infilling Amount & Type Surface Shape Roughness Spacing (Joint Sets)
Boring Log Data Typical Drill Hole Logs Rock Log Soil Log
Boring Log Data Data Compilation Summary Sheets
Boring Log Data Core Photos
Field Testing Data Appendix Field Testing Data Pressure meter/dilatometer Hydraulic conductivity testing Hydraulic jacking/fracturing Hazardous gas sampling
Field Testing Data In Situ Testing Pressure Meter / Dilatometer
Field Testing Data In Situ Testing Hydraulic Conductivity Testing Packer Testing (single and double) Constant Head Falling Head Tunnel Alignment Relates to permeability and groutability of a formation (rock or soil) for parameters used in analysis, and design.
Field Testing Data Packer Tests Inflation Tube Inflatable Packer End Cap Test Zone Perforated Screen End Plug
Field Testing Data Packer Tests 0.0E+00 5.0E-04 1.0E-03 1.5E-03 2.0E-03 1 K(cm/s) 2 3 4 5
Field Testing Data Packer Testing Results
Field Testing Data Hydraulic Jacking and Fracturing Tests Jacking Fracturing Pressurization of borehole is done until fracturing of rock in borehole wall. The rock will generally fracture in the direction perpendicular to the minimum stress direction σ3. The fracture alignment is viewed using borehole televiewer or impression packer. The intermediate and vertical stresses are then calculated from the estimated minimum stress value
Field Testing Data Hazardous Gases & Contaminants Underground Methane (CH4) Hydrogen Sulfide (H2S) Carbon Dioxide (CO2) Gasoline Vapors Chlorinated Solvents (PCE, DCE, & TCE)
Field Testing Data Sample Screening Pore gas sampling Groundwater sampling
Geophysics Appendix Geophysics Down hole geophysics Seismic reflection* Seismic refraction Resistivity Suspension logging Ground penetrating radar Seismic tomography* Bathymetry Magnetics*
Geophysics Geophysics Downhole Methods
Geophysics Downhole Summary Plots
Geophysics Suspension Logging
Geophysics Seismic Refraction Refraction Compression, P-Wave
Geophysics Geophysics - Seismic
Geophysics Marine Geophysics
Geophysics Seismic Reflection Profile
Geophysics Magnetic Survey
Geophysics 3D Resistivity Imaging
Geophysics Ground Penetrating Radar (Example: Performed Inside Tunnel)
Groundwater Data Appendix Groundwater Data Water level monitoring table Well installation completion logs Piezometer data Slug tests and pump testing
Groundwater Data Groundwater and Hydrogeologic Conditions
Groundwater Data Piezometers Typical stand-pipe piezometer Multi-level Single Multi-level vibrating wire piezometer Fully Grouted Multi-level vibrating wire piezometer
Groundwater Data Pump / Slug Tests
Groundwater Data Piezometer Completion Diagram
Groundwater Data Measuring the Phreatic Surface
Laboratory Testing Data Appendix Laboratory Testing Data Data summary table Individual data sheets, sorted by test type Moisture content and unit weight Specific gravity Seive and hydrometer Atterberg limits Shear strength Consolidation Slake durability and LA Abrasion CERCHAR and Brazilian tensile strength Triaxial testing Corrosion testing
Laboratory Testing Data Typical Lab Testing Soil USCS classification Strength & Modulus Moisture/density Plasticity Gradation Hydrometer
Laboratory Testing Data Unified Soil Classification System (USCS)
Laboratory Testing Data Grain Size Analysis
Laboratory Testing Data Plasticity Testing (Atterberg Limits: PI, LL, PL)
Laboratory Testing Data Hydrometer Test
Laboratory Testing Data Density & Strength
Laboratory Testing Data Different Conditioners Dispersants Foam Injection Ratios High Density Limestone Slurry Bentonite Polymer
Laboratory Testing Data Specialized Lab Testing Soil Abrasivity
Laboratory Testing Data Typical Lab Testing Rock Rock classification Compressive/shear strength Tensile strength (Brazilian) Moisture/density Durability, abrasivity, slake, toughness
Laboratory Testing Data Unconfined Compressive Strength Brazilian Tensile Strength Resiliency (Toughness)
Laboratory Testing Data Specialized Lab Testing Punch Penetration and Cerchar Tests
Laboratory Testing Data Point Load Index Tests
Laboratory Testing Data Slake Durability Tests
Laboratory Testing Data Thin Section Analysis Granitic Porphyry
Conclusion Organization is Key Proper organization is integral to writing a functional and useful geotechnical data report The purpose should be to present the data in a clear manner that allows the designer to find data quickly and easily
Conclusion A thorough, robust geotechnical investigation is the best risk mitigation strategy.
Conclusion Questions?