Greg Raines, PEGregory.Raines@Stantec.com

Underground Risk

Management CourseMarina Del Rey, California

November, 2018

Geotechnical Data

Reports

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.

Introduction

Geologic Profile

LEGEND

Geologic Profile

LEGEND

Geotechnical Reports

Geotechnical Reports

Contract Document

GDRData Only

GBRInterpretive Baseline

Non-Contract Document

GDMInterpretive 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 Overview2. Area Geology

a) Geologic Mapb) Seismic setting and regional faultsc) Definition of relevant geologic terms

3. Field Investigationa) Boring logs and rock core photosb) Logging proceduresc) Drilling proceduresd) Groundwater evaluatione) Field testing

4. Laboratory Testinga) Testing standardsb) Testing strategyc) Types and number of testsd) Results summary

Introduction

Geotechnical Data Report Appendices

1. Geological Reconnaissance and Mapping2. Boring Log data3. Field Testing Data4. Geophysics5. Groundwater data6. Laboratory data7. Historical Data

Introduction

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 MappingGeological 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)

Geological Reconnaissance and Mapping

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 conditionsCons:• 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 TestingBoring Log Data

Types of Rigs – Rock CoreBoring 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 LogsRock Log Soil Log

Boring Log Data

Data Compilation Summary SheetsBoring Log Data

Core PhotosBoring Log 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 /

DilatometerField 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

Perforated Screen

Inflatable Packer

Test Zone

End Cap

End Plug

Field Testing Data

Packer Tests

0.0E+00 5.0E-04 1.0E-03 1.5E-03 2.0E-03

1

2

3

4

5

K(cm/s)

Field Testing Data

Packer Testing ResultsField Testing Data

Hydraulic Jacking and Fracturing Tests

Jacking

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

Fracturing

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

Groundwater samplingPore gas sampling

Sample Screening

Field Testing Data

Appendix – Geophysics

• Down hole geophysics• Seismic reflection*• Seismic refraction• Resistivity• Suspension logging• Ground penetrating radar• Seismic tomography*• Bathymetry• Magnetics*

Geophysics

Geophysics – Downhole MethodsGeophysics

Downhole Summary PlotsGeophysics

Suspension LoggingGeophysics

Seismic Refraction

Refraction Compression, P-Wave

Geophysics

Geophysics - SeismicGeophysics

Marine GeophysicsGeophysics

Seismic Reflection ProfileGeophysics

Magnetic SurveyGeophysics

3D Resistivity ImagingGeophysics

Ground Penetrating Radar –

(Example: Performed Inside Tunnel)Geophysics

Appendix – Groundwater Data

• Water level monitoring table • Well installation completion logs• Piezometer data• Slug tests and pump testing

Groundwater Data

Groundwater and Hydrogeologic

ConditionsGroundwater Data

Piezometers

Typical stand-pipe piezometer

Multi-level vibrating wire piezometer

Fully Grouted Multi-level vibrating wire piezometer

Multi-level Single

Groundwater Data

Pump / Slug TestsGroundwater Data

Piezometer Completion DiagramGroundwater Data

Measuring the Phreatic SurfaceGroundwater 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 AnalysisLaboratory 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 AbrasivityLaboratory 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 TestsLaboratory Testing Data

Laboratory Testing Data Slake Durability Tests

Thin Section Analysis

Granitic Porphyry

Laboratory Testing Data

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? Conclusion