Two aspects of seismically-induced liquefaction are discussed which are of vital engineering significance: the triggering condition and the consequences of liquefaction. The triggering condition is examined with respect to liquefaction analysis, note being taken of the onset condition which is governed by cyclic strength. Consequences of liquefaction are discussed with respect to post-seismic stability analysis, in which the residual strength plays a major role. Procedures used for liquefaction analysis based on the results of in situ sounding tests are introduced, and the applicability of this method for estimating associated ground settlements is discussed. The evaluation of residual strength requires a better understanding of undrained sand behaviour. Results of extensive laboratory rests on Japanese standard sand are examined and new index parameters are proposed to quantify undrained sand behaviour better. The results of laboratory tests on silty sands are examined in the same way. AH the results are...

Liquefaction and flow failure during earthquakes.

Soil liquefaction is a major concern for structures constructed with or on sandy soils. This paper describes the phenomena of soil liquefaction, reviews suitable definitions, and provides an update...

Evaluating cyclic liquefaction potential using the cone penetration test

A simplified procedure using shear-wave velocity measurements for evaluating the liquefaction resistance of soils is presented. The procedure was developed in cooperation with industry, researchers, and practitioners and evolved from workshops in 1996 and 1998. It follows the general format of the Seed-Idriss simplified procedure based on standard penetration test blow count and was developed using case history data from 26 earthquakes and >70 measurement sites in soils ranging from fine sand to sandy gravel with cobbles to profiles including silty clay layers. Liquefaction resistance curves were established by applying a modified relationship between the shear-wave velocity and cyclic stress ratio for the constant average cyclic shear strain suggested by R. Dobry. These curves correctly predicted moderate to high liquefaction potential for >95% of the liquefaction case histories and are shown to be consistent with the standard penetration test based curves in sandy soils. A case study is provided to illustrate application of the procedure. Additional data are needed, particularly from denser soil deposits shaken by stronger ground motions, to further validate the simplified procedure.

Liquefaction resistance of soils from shear-wave velocity

The electric cone penetration test (CPT) has been in use for over 40 years and is growing in popularity in North America. This paper provides some recent updates on the interpretation of some key g...

Interpretation of cone penetration tests — a unified approach

Granted that good site control is exercised in carrying out the standard penetration test the energy delivered to the sampler, and therefore the blow count obtained in any given sand deposit at a particular effective overburden pressure, can still vary to a significant extent depending on the method of releasing the hammer, on the type of anvil and on the length of rods (if less than 10 m). For consistency it is essential to correct the observed blow count N to the value which would have been measured using a specified rod energy. A recommended value, which should be recognized internation- ally, is 60% of the free-fall energy of the standard hammer weight and drop. The corrected blow count is then designated as N60 and the normalized value (N1)60 at unit effective pressure (1 kg/cm2 or 100 kPa) may be regarded as a basic characteristic of the sand. Factors controlling the rod energy ratio are examined in detail and methods of deriving N60 values are developed. An examination of selected field and laborat...

Standard penetration test procedures and the effects in sands of overburden pressure, relative density, particle size, ageing and overconsolidation

Significant advances have been made in recent years in research, development, interpretation, and application of cone penetration testing. The addition of pore pressure measurements during cone pen...

Interpretation of cone penetration tests. Part I: Sand

The piezometer cone is generally regarded as the most efficient tool for stratigraphic logging of soft soils. A thin pore pressure element (5 mm thick) can sense layers a few centimeters thick. However, there remains some uncertainty with regard to the interpretation and use of the piezometer cone data for engineering applications. This paper summarizes some of the experience with piezometer cone testing and its use in the Vancouver, B. C. , Canada area.

Use of Piezometer Cone Data

Existing methods for the evaluation of liquefaction potential using data obtained from the Cone Penetration Test (CPT) are reviewed. A modified CPT‐based method for the liquefaction assessment of sand is presented. Information available on the liquefaction of silty sands is reviewed, and a procedure for considering the influence of silt content is also presented. Field and laboratory data from Canada, Japan, China and the United States are presented to provide a preliminary evaluation of the proposed CPT‐based liquefaction assessment methods.

Liquefaction Potential of Sands Using the CPT

A new test, called the seismic cone penetration test (SCPT) is described. A small rugged velocity seismometer has been incorporated into an electronic cone penetrometer. The combination of the seismic downhole method and the CPT logging provide an extremely rapid, reliable, and economic means of determining stratigraphic strength and modulus information in one sounding. Results using the seismic cone penetration test are presented and compared to conventional in situ techniques.

Seismic Cpt to Measure in Situ Shear Wave Velocity

A method for estimating equivalent Standard Penetration Test (SPT) N‐values from Cone Penetration Test (CPT) data has been presented accounting for variations in soil grain size and SPT energy input. A discussion is given regarding the problems associated with the SPT and how these relate to SPT‐CPT correlations. A historical review of SPT‐CPT correlations is presented with additional recent data that include energy measurements during the SPT. An example is given to illustrate how the SPT data can be rationalized using energy corrections. Also, a chart is provided to estimate mean grain size from CPT data.

R. G. Campanella

Papers

Interpretation of cone penetration tests. Part I: Sand

Use of Piezometer Cone Data

Liquefaction Potential of Sands Using the CPT

Seismic Cpt to Measure in Situ Shear Wave Velocity

Spt-cpt correlations