Field Tests soil parameters

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Presentation Transcript

FIELD TESTS Determination of Various Soil Parameters : 

FIELD TESTS Determination of Various Soil Parameters Presented By: MUHAMMAD JUNAID GHAURI

Contents : 

Contents Introduction Field Tests Merits/Demerits Parameters Obtained Summary Conclusion

Introduction : 

Introduction Why Field Tests Determine Soil Parameters Insitu Identify Stratrigraphy Testing Soil Sample Undisturbed Advantages Over Lab Testing Less Time Consuming More Reliable Presents near to actual state of soil at Site

Different Field Tests : 

Different Field Tests Direct Methods Standard Penetration Test (SPT) Cone Penetration Test (CPT) Pressure Meter Test (PMT) Dilatometer Test (DMT) Vane Shear Test (VST) Plate Load Test (PLT)

General Applications : 

General Applications

Different Field Tests Cont. : 

Different Field Tests Cont. Cone Penetrometer Dilatometer Pressure meter Vane Shear

Different Field Tests Cont. : 

Different Field Tests Cont. Indirect Method / Wave Propagation Seismic Survey Mechanical Wave Measurements Cross-Hole Seismic Tests (CHT) Down-Hole Seismic Tests (DHT) Seismic Refraction Electromagnetic Wave Measurements Ground Penetrating Radar (GPR) Surface Resistivity (SR) Magnetometer Surveys (MT)

Standard Penetration Test (SPT) : 

Standard Penetration Test (SPT) Most Frequently used & cheapest of all available Field Tests Developed in 1927 & Standardized in 1958 Standard Used is ASTM D-1586 Parameter Obtained SPT ‘N’ Value (No. of blows/ft of penetration)

Standard Penetration Test (SPT) Cont. : 

Standard Penetration Test (SPT) Cont. Advantages: Quick & simple to perform Equipment & Expertise easily available Can penetrate into dense layers, gravel & fill Provides a representative sample Disadvantages: Does not provide continuous data (5ft interval) Limited applicability to cohesive soils, gravels, boulders, cobbles A No. of corrections are to be applied in order to get a standard value

Cone Penetration Test (CPT) : 

Cone Penetration Test (CPT) Developed in Netherlands so also called as Dutch Cone Test (DCT) Standard followed are ASTM D-3441 & ASTM D-5778 Types of Cone Penetration Tests Mechanical CPT Electric CPT Piezo Cone Electric Piezo/Friction Seismic Cone

Cone Penetration Test (CPT) Cont. : 

Cone Penetration Test (CPT) Cont. Parameters Obtained Cone End Resistance ‘qc’ Sleeve Resistance ‘qf’ Friction Ratio ‘FR’ Advantages The test can be performed on a wide range of soil types It provides a continuous or near continuous data

Cone Penetration Test (CPT) Cont. : 

Cone Penetration Test (CPT) Cont. Disadvantages The test does not provide any soil samples It cannot penetrate into very dense soils or soils containing boulders and cobbles

Pressure Meter Test (PMT) : 

Pressure Meter Test (PMT) Developed by Maynard in 1956 Standard followed is ASTM D 4719 Types of Pressure Meters Maynard Pressure Meter Self Boring Pressuremeter Screw Plate Pressuremeter Parameters Obtained Po = Lift off pressure Pf = Yield pressure Pl = Limit pressure

Pressure Meter Test (PMT) Cont. : 

Pressure Meter Test (PMT) Cont. Advantages Allows assessment of in-situ horizontal stress Allows direct measurement of shear stiffness and undrained strength Well conditioned boundary conditions Disadvantages Not very cheap Operators need to be skilled An appreciable amount of data processing is required

Dilatometer Test (DMT) : 

Dilatometer Test (DMT) Developed by Marchietti in 1980 A "Standard Test Method for Performing the Flat Plate Dilatometer" is currently being prepared by ASTM (approved Draft 2001). Types of Dilatometers Marchietti Dilatometer (MDMT) Akbar Newcastle Dilatometer (ANDMT) Parameters Obtained ED = Dilatometer Modulus KD = Lateral Stress Index ID = Material Index

Dilatometer Test (DMT) Cont. : 

Dilatometer Test (DMT) Cont. Advantages Settlement prediction has been considered more reliable than any other test DMT can evaluate the OCR & Ko of any type of soil Horizontal coefficient of consolidation & horizontal permeability can be determined Can identify active or old slip surfaces in clay slopes using KD profiles of DMT Disadvantages No Sample is recovered Blade penetration effects the strength, stiffness Results of DMT are affected if the blade drifts out from veritical during penetration

Field Vane Shear Test (FVST) : 

Field Vane Shear Test (FVST) Primarily used for Clays Determines Insitu Undrained Shear Strength su,v Standard used is ASTM D-2573 Parameter Obtained T = Vane Torque

Field Vane Shear Test (FVST) Cont. : 

Field Vane Shear Test (FVST) Cont. Advantages Rapid and economical test Reproducible results in homogeneous soils Equipment and test are simple Long history of use in engineering practice Inexpensive method for measuring clay sensitivity. Disadvantages Limited to soft to stiff cohesive soils Field vane shear strength must be corrected Results can be affected by anisotropic soils, sand lenses, shells, and seams.

Comparison : 

Comparison Qualitative relationship between relative subsurface exploration cost and reliability (after Handy, 1980).

Slide 20: 

Correlations

Correlations from SPT ‘N’ : 

Correlations from SPT ‘N’ Unit Weight ‘γ’ Relative Density ‘Dr’ Angle of Internal Friction ‘Φ’ Undrained Compressive Strength ‘qu’

Correlations from SPT ‘N’ Cont. : 

Correlations from SPT ‘N’ Cont. Granular Soils (Sands, Silty Sands) (Terzaghi & Peck)

Correlations from SPT ‘N’ Cont. : 

Correlations from SPT ‘N’ Cont. Cohesive Soils (Clays, Silty Clays) (Terzaghi & Peck)

Correlations from CPT : 

Correlations from CPT Classification of Soil Undrained Shear Strength ‘su’ Relative Density ‘Dr’ Angle of Internal Friction ‘Φ’

Correlations from CPT Cont. : 

Correlations from CPT Cont. Soil Classification Chart

Correlations from CPT Cont. : 

Correlations from CPT Cont. Shear Strength ‘su’

Correlations from CPT Cont. : 

Correlations from CPT Cont. Relative Density ‘RD’

Correlations from CPT Cont. : 

Correlations from CPT Cont. Angle of Internal Friction ‘Φ’

Correlations from PMT : 

Correlations from PMT Shear Modulus ‘G’ Undrained Shear Strength ‘cu’ Over Consolidation Ratio ‘OCR’ Coefficient of Earth Pressure at Rest ‘Ko’

Correlations from PMT Cont. : 

Correlations from PMT Cont. Typical Pressuremeter Graph Δp ΔV

Correlations from PMT Cont. : 

Correlations from PMT Cont. Shear Modulus ‘G’ Es = Modulus of Elasticity of Soil µs= Poisson’s Ratio Vo= Cell Volume corresponding to pressure po or

Correlations from PMT Cont. : 

Correlations from PMT Cont. Coefficient of Earth Pressure at Rest ‘Ko’ σ’ = effective vertical stress at test depth po = insitu lateral pressure

Correlations from PMT Cont. : 

Correlations from PMT Cont. Undrained Shear Strength ‘cu’ pL = Limit Pressure (ksf) σho= insitu horizontal stress (ksf) Gs= Shear Modulus

Correlations from FVST : 

Correlations from FVST Undrained Shear Strength ‘cu’ Tv = vane torque, kips ft Kv = constant depending on the dimensions and shape of the vane, ft3

Correlations from DMT : 

Correlations from DMT Classification of Soil Coefficient of Earth Pressure at rest ‘Ko’ Over Consolidation Ratio ‘OCR’

Correlations from DMT Cont. : 

Correlations from DMT Cont. Dilatometer Modulus ‘ED’ Es = Modulus of Elasticity µ = Poisson’s Ratio p1 = initial pressure or Liftoff pressure p2 = pressure corresponding to membrane expansion of 1.1mm

Correlations from DMT Cont. : 

Correlations from DMT Cont. Lateral Stress Index ‘KD’ po = γz =overburden pressure Material Index ‘ID’

Correlations from DMT Cont. : 

Correlations from DMT Cont. Classification of Soil

Correlations from DMT Cont. : 

Correlations from DMT Cont. Coefficient of Earth Pressure at rest ‘Ko’

Correlations from DMT Cont. : 

Correlations from DMT Cont. Over Consolidation Ratio ‘OCR’ OCR = (nKD)m

Summary of Correlations : 

Summary of Correlations

Summary of Correlations Cont. : 

Summary of Correlations Cont.

Summary of Correlations Cont. : 

Summary of Correlations Cont.

References : 

References “Geotechnical Engineering” by Gulhati & Datta “Fundamentals of Soil Mechanics” by M.S.Qureshi & Aziz Akbar “Foundation Analysis & Design” by Joseph E. Bowles “Principles of Geotechnical Engineering” by Braja M. Das “Development of Correlations among Various Site Characterization Methods” by Engr. Muhammad Arshad www.geotechlink.com EM 1110-1-1905

THANKS! : 

THANKS!

Any Questions! : 

Any Questions!