Evaluation of Flow Liquefaction and Liquefied Strength Using the Cone Penetration Test: an update

2021 ◽  
Author(s):  
Peter Robertson
Keyword(s):  
Shear Strength ◽  
Large Strain ◽  
Strength Loss ◽  
Undrained Shear Strength ◽  
Technical Note ◽  
Published Data ◽  
Recent Experience ◽  
Case Histories ◽  
Flow Liquefaction ◽  
Undrained Shear

Robertson (2010a) outlined a method to evaluate the susceptibility of soils to undrained strength loss that could result in flow liquefaction as well as a method to estimate the resulting liquefied undrained shear strength of predominately sand-like soils using the CPT. Based on published data and recent case histories this technical note describes a recommended update to the Robertson (2010a) method to estimate the large strain liquefied or remolded undrained shear strength for both sand-like and clay-like soils as well as soils and that transition from sand-like to clay-like. The proposed update acknowledges that soil behavior can vary from sand-like to clay-like and that CPT interpretation to estimate large strain undrained shear strength changes due to the changing drainage conditions during the CPT. The updated method builds upon previously published data combined with recent experience and case histories.

Reconsideration of case histories for estimating undrained shear strength in sandy soils

1999 ◽  
Vol 36 (5) ◽  
pp. 907-933 ◽  
Author(s):  
C E (Fear) Wride ◽  
E C McRoberts ◽  
P K Robertson
Keyword(s):  
Shear Strength ◽  
Sandy Soils ◽  
Standard Penetration Test ◽  
Undrained Shear Strength ◽  
Soil Liquefaction ◽  
Penetration Test ◽  
Case Histories ◽  
Original Case ◽  
Undrained Strength ◽  
Undrained Shear

When sandy soils respond in a strain-softening manner to undrained loading, an estimation of the resulting undrained shear strength (Su) is required to determine the potential for flow liquefaction at a given site. One of the most commonly used methods for estimating the undrained strength of liquefied sand is an empirical standard penetration test (SPT) based chart (originally proposed by H.B. Seed), which was developed using a number of case histories. The original interpretations of these case histories are viewed by many workers and regulatory agencies as the most authoritative measure of the liquefied strength of sand. Consequently, in comparison, other less conservative methods are generally held in an unfavourable light. This paper reexamines the original database of case histories in view of some more recent concepts regarding soil liquefaction. The objectives of this paper are to explore and reassess the issues involved in the original assessment and to offer alternative views of the case records. The conclusions presented here indicate that alternative explanations of the liquefied strength of sand are not inconsistent with the original case histories. Key words: sandy soils, soil liquefaction, undrained strength, standard penetration test (SPT).

Disturbance effects in pressuremeter tests in clay

2004 ◽  
Vol 41 (4) ◽  
pp. 738-759 ◽  
Author(s):  
Vincenzo Silvestri
Keyword(s):  
Shear Strength ◽  
Strain Curve ◽  
Undrained Shear Strength ◽  
Case Histories ◽  
Stress Strain ◽  
Test Analysis ◽  
Hardening Material ◽  
Expansion Test ◽  
Undrained Shear

This paper analyzes the effect of borehole disturbance, caused by installation of pressuremeter probes in clays, on the derived stress–strain curves. Both overpushing- and overcutting-induced disturbances are considered. It is shown that overpushing results in underestimation of the undrained shear resistance. In general, the degree of underestimation cannot be determined. As for overcutting, the derived stress–strain curves are characterized by high peak strengths. The degree of overestimation of the undrained shear strength may reach 100% for the case of a strain-hardening material. Determination of the strain that corresponds to the peak shear strength allows determination of the true stress–strain curve from the expansion test. Analysis of four well-documented case histories serves to illustrate the proposed approach.Key words: pressuremeter, borehole disturbance, clay, stress-strain curves, case histories, undrained shear strength.

New stability method for embankments on clay foundations

1982 ◽  
Vol 19 (1) ◽  
pp. 44-48 ◽  
Author(s):  
Robert P. Chapuis
Keyword(s):  
Shear Strength ◽  
Stress Analysis ◽  
Undrained Shear Strength ◽  
Direct Application ◽  
Published Data ◽  
Total Stress ◽  
Preconsolidation Pressure ◽  
Stability Method ◽  
Undrained Shear ◽  
Clay Foundations

The proposed method makes use of a conventional total stress analysis, corrected to take into consideration the preconsolidation pressure and the undrained shear strength profiles. Good results are obtained for seven well documented cases of embankment failures, the data of which allow a direct application of the proposed method. Many other failure cases, for which the published data are insufficient to allow such a direct application, are analysed on a statistical basis using a relationship between cuσp′ and Ip. Bjerrum's correction appears as a particular case, only statistically applicable, of the proposed method.

Undrained shear strength of clean sands to trigger flow liquefaction: Reply

2001 ◽  
Vol 38 (3) ◽  
pp. 654-657 ◽  
Author(s):  
M Yoshimine ◽  
P K Robertson ◽  
C E (Fear) Wride
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Flow Liquefaction ◽  
Undrained Shear
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