Liquefaction Evaluation Research Articles

Evaluation of soil liquefaction in the Chi-Chi, Taiwan earthquake using CPT

During the 1999 Chi-Chi, Taiwan earthquake, many sand boiling phenomena were observed in central Taiwan, which caused severe ground settlement and structure damages. According to the installed accelerograms, the peak ground surface horizontal accelerations in the liquefaction-affected areas range from 774.42 to 121.3 gal. The writers carried out an extensive investigation of soil liquefaction in this earthquake. In this paper, we present results of the CPT exploration and post-earthquake liquefaction analysis. Two hundred and seventy five (275) cone penetration test data were collected from the liquefaction-affected areas, and 46 liquefaction case histories and 88 non-liquefaction case histories were derived that can be used to evaluate the accuracy of existing liquefaction evaluation models. In addition, the strength of the liquefied soils after earthquake and the implication of its liquefaction potential in the future event are discussed.

Comparing liquefaction evaluation methods using penetration- VS relationships

Three methods that follow the general format of the Seed-Idriss simplified procedure for evaluating liquefaction resistance of soils are compared in this paper. They are compared by constructing relationships between penetration resistance and small-strain shear–wave velocity ( V S) implied from cyclic resistance ratio (CRR) curves for the three methods, and by plotting penetration- V S data pairs. The penetration- V S data pairs are from 43 Holocene-age sand layers in California, South Carolina, Canada, and Japan. It is shown that the V S-based CRR curve is more conservative than CRR curves based on the Standard Penetration Test (SPT) and Cone Penetration Test (CPT), for the compiled Holocene data. This result agrees with the findings of a recent probability study where the SPT-, CPT-, and V S-based CRR curves were characterized as curves with average probability of liquefaction of 31, 50, and 26%, respectively. New SPT- and CPT-based CRR equations are proposed that provide more consistent assessments of liquefaction potential for the Holocene sand layers considered.

Guide for Shear-Wave-Based Liquefaction Potential Evaluation

Small-strain shear-wave velocity measurements provide a promising approach to liquefaction potential evaluation. In some cases, where only seismic measurements are possible, it may be the only alternative to the penetration-based approach. Various investigators have developed relationships between shear wave velocity and liquefaction resistance. Successful application of any liquefaction evaluation method requires that procedures used in their development also be used in their application. This paper presents detailed guidelines for applying the procedure described in Andrus and Stokoe that was developed using suggestions from two workshops and following the general format of the Seed-Idriss simplified procedure. Correction factors to velocity and liquefaction resistance for soil aging are suggested. Based on the work by Juang et. al., factors of safety of 1.0, 1.2, and 1.5 correspond to probabilities of liquefaction of about 0.26, 0.16, and 0.08, respectively. Additional field performance data are needed from all soil types, particularly denser and older soil deposits shaken by stronger ground motions, to further validate the recommended procedure.

A study of the liquefaction risk potential at Yuanlin, Taiwan

The method by Iwasaki et al. [Iwasaki, T., Arakawa, T., Tokida, K., 1982. Simplified procedures for assessing soil liquefaction during earthquakes. Proceedings of the Conference on Soil Dynamics and Earthquake Engineering, Southampton, UK, pp. 925–939] for evaluating the liquefaction failure potential is widely used in Japan, Taiwan, and other countries due to its ease of use and general applicability. In this method, an index, called the Liquefaction Potential Index ( I L), is calculated based on an integration of the calculated factor of safety ( F s) over depth with a weighting function. Iwasaki et al. (1982) provided a set of criteria to interpret the calculated index I L based on a calibration with his dataset of field performance cases. However, in their method, the factor of safety ( F s) is based on the liquefaction evaluation method adopted in the Japanese Highway Bridge Design Code [JSHE, 1990. Highway Bridge Design Guide Book. Japan Society of Highway Engineering, in Japanese]. Whether other liquefaction evaluation methods can be used in conjunction with the index I L or not needs further investigation. In this paper, the Cone Penetration Test (CPT) data from Yuanlin, Taiwan, the area that suffered the most from liquefaction in the 1999 Chi-Chi, Taiwan, earthquake, are analyzed. Three CPT-based methods are used for the calculation of the factor of safety for these cases derived from the Chi-Chi earthquake. These factors of safety are used to define the liquefaction potential and risk indexes. The calculated indexes are then used to construct the failure potential maps, and these maps are checked with the field observations. The study shows that the Liquefaction Risk Index ( I R) defined in conjunction with the Juang et al. [Juang, C.H., Yuan, H., Lee, D.H., Lin, P.S., 2003. Simplified CPT-based method for evaluating liquefaction potential of soils. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, vol. 129, no. 1, pp. 66–80] method yields the best result in interpreting field observations.

In-situ Properties of Soils at Paleoliquefaction Sites in the South Carolina Coastal Plain

Examination of in-situ properties of soils at four paleoliquefaction sites in the South Carolina Coastal Plain (SCCP) indicated that the soil conditions at these sites are all consistent with liquefiable soils at other locations where liquefaction has been observed. The index properties of soils at locations where sandblows were encountered are not apparently different from those of neighboring locations where sandblows were not encountered. The source sands at the four sites are all loose to medium dense, poorly graded, fine sands. The mean grain sizes range from 0.15 to 0.2 mm and fines contents are less than 10%. They are all located at very shallow depth (1.3 to 3.7 m). An underlying clay layer directly beneath the source sands at all sites of liquefaction may amplify the ground motion and make the source sands more susceptible to liquefaction. We found that some of the soil properties for the paleoliquefaction sites in the SCCP differ from the currently used liquefaction evaluation curves that are based on data for Holocene soils from California, China, and Japan. To facilitate paleoliquefaction evaluation in the SCCP, penetration resistance and shear-wave velocity data at paleoliquefaction sites were carefully examined and compared with current standards to develop boundary curves for paleoliquefaction evaluation in the SCCP.

Modelling of seismically induced liquefaction under high confining stress

Evaluation of seismically-induced liquefaction under high confining stress, such as might relate to the foundation soil under large earth dams, is based on the extrapolation of observed behavior and correlations at shallow depths. In practice, the behavior of saturated sand and other cohesionless soils under these conditions is not well understood. Experiments were conducted, at the 100 g-ton RPI centrifuge facility, to investigate confining stress effects on liquefaction potential, under the boundary and loading conditions of a deep horizontal saturated sand deposit. Three level ground models, with either a homogeneous profile or a dense layer over a loose layer, were tested in a laminar box. In two of the models, a steel plate surcharge was placed on the soil to increase confinement. Recorded accelerations and pore pressures, vertical surface settlement, and shear strains and stresses derived from the accelerations using System Identification, were analyzed to study the effect of high confining stress on the development of soil liquefaction.

Assessing Probability-based Methods for Liquefaction Potential Evaluation

This paper presents an assessment of existing and new probabilistic methods for liquefaction potential evaluation. Emphasis is placed on comparison of probabilities of liquefaction calculated with two different approaches, logistic regression and Bayesian mapping. Logistic regression is a well-established statistical procedure, whereas Bayesian mapping is a relatively new application of the Bayes’ theorem to the evaluation of soil liquefaction. In the present study, simplified procedures for soil liquefaction evaluation, including the Seed–Idriss, Robertson–Wride, and Andrus–Stokoe methods, based on the standard penetration test, cone penetration test, and shear wave velocity measurement, respectively, are used as the basis for developing Bayesian mapping functions. The present study shows that the Bayesian mapping approach is preferred over the logistic regression approach for estimating the site-specific probability of liquefaction, although both methods yield comparable probabilities. The paper also co...

Assessing CPT-based methods for liquefaction evaluation with emphasis on the cases from the Chi-Chi, Taiwan, earthquake

In the early morning (1:47 Taiwan time) of September 21, 1999, the largest earthquake of the century in Taiwan ( M w=7.6, M L=7.3) struck this island country. The earthquake killed more than 2400 people and caused great destruction to buildings, bridges, dams, highways, and railways. One of the causes for heavy damages to the structures is soil liquefaction and ground settlement during the earthquake. In this paper, investigation of soil liquefaction and case histories of liquefaction are presented. Three CPT-based simplified methods, the Robertson method, the Olsen method, and the Juang method, are examined using the case histories derived from the Chi-Chi earthquake. The results of the comparison show that the Juang method is more accurate than the two methods in predicting liquefaction potential of soils based on the cases derived from the Chi-Chi earthquake, although all three methods are quite comparable in accuracy.

Liquefaction evaluation guidelines for practicing engineering and geological professionals and regulators

Abstract Liquefaction is a seismic hazard that must be evaluated for a significant percentage of the developable areas of California. The combination of the presence of active seismic faults, young loose alluvium, and shallow ground water are the ingredients that could result in the occurrence of liquefaction in many areas of California. These ingredients are also found in other seismically active areas of the United States and the world. The state of California, through the Seismic Hazard Mapping Act of 1990, has mandated that liquefaction hazard be determined for new construction. On a parallel track, the Uniform Building Code, since 1994, has provisions requiring the determination of liquefaction potential and mitigation of related hazards, such as settlement, flow slides, lateral spreading, ground oscillation, sand boils, and loss of bearing capacity. Fortunately, the state of knowledge has now evolved to where there are field exploration methods and analytical techniques to estimate the liquefaction potential and the possible consequences arising from the occurrence of liquefaction. There are some areas that still need further research. Mitigation for liquefaction has become more commonplace and confidence in these techniques has been increased based on the relatively successful performance of improved sites in the past several major earthquakes. Unfortunately, not all practicing engineering and geological professionals and building officials are knowledgeable about the current state-of-practice in liquefaction hazard analysis and mitigation. Thus, it was considered necessary to develop a set of guidelines to aid professionals and building officials, based on California's experience with the current practice of liquefaction hazard analysis and mitigation. Although the guidelines reported in this paper were written specifically for practice in California, it is believed that guidelines can benefit practitioners to evaluate liquefaction hazard in all seismic regions.

EVALUATION OF LIQUEFACTION OF DECOMPOSED GRANITE SOILS BY MEANS OF FLOW LIMIT AND DISSIPATION ENERGY

EVALUATION OF LIQUEFACTION OF DECOMPOSED GRANITE SOILS BY MEANS OF FLOW LIMIT AND DISSIPATION ENERGY

Evaluation of Liquefaction Using Disturbed State and Energy Approaches

The disturbed state concept (DSC) and the dissipated energy approach can provide simplified, fundamental, and mechanistic methods for the identification of the initiation and growth of liquefaction in saturated soils under cyclic and earthquake loading. Both approaches are developed and used for the analysis of liquefaction in the soil deposits at Port Island, Kobe, Japan, during the Hyogo-ken Nanbu earthquake. They are also used to analyze liquefaction of two sands during laboratory cyclic tests using torsional and multiaxial devices. It is shown that the DSC and energy criteria can lead to improved understanding of the mechanism of liquefaction, and to rational and simplified procedures compared to those based on empirical and index properties. Furthermore, the DSC possesses certain advantages over the energy approaches, particularly in terms of its implementation in computer (finite-element) programs for dynamic and liquefaction analysis.

Liquefaction and Lateral Spread Evaluation and Mitigation for Highway Overpass Structure: Cherry Hill Interchange, Davis County, Utah

Transportation structures constructed in areas of significant seismic hazards are subject to lateral and vertical movements that can threaten the integrity of structures built on liquefiable subsoils. This case history summarizes the geology, analysis methods, mitigation requirements, and proposed quality control for the Cherry Hill Interchange project in Davis County, Utah. A liquefaction and lateral spread liquefaction hazard during the design earthquake has been identified that threatens failure of the proposed bridge. Cone penetration tests were determined to be a cost-effective method for supplementing standard penetration test borings to gain sufficient subsurface information for the liquefaction and lateral spread analysis. A cost-effective solution for protecting the bridge from the hazard has been developed using geotechnical principles combined with recent developments in liquefaction mitigation. The cost of the mitigation is a minor percentage of the overall project cost but is anticipated to protect the bridge from collapse and save lives.

A rational method for development of limit state for liquefaction evaluation based on shear wave velocity measurements

This papers presents a new approach for developing a limit state for liquefaction evaluation based on field performance data. As an example to illustrate the new approach, a database that consists of, among many other features, in situ shear wave velocity measurements and field observations of liquefaction/non-liquefaction in historic earthquakes is analysed. This database is first used to train a neural network to classify liquefaction/non-liquefaction based on soil resistance parameters and load parameters. The successfully trained and tested neural network is then used to establish a limit state, a multiple dimension boundary that separates ‘zone’ of liquefaction from ‘zone’ of non-liquefaction. The limit state yields cyclic resistance ratio for a given set of soil resistance parameters. Examination of all cases in the database show that the developed limit state has a high degree of accuracy in predicting the occurrence of liquefaction/non-liquefaction. The developed neural network model can accurately predict the cyclic resistance ratio of soils. Copyright © 2000 John Wiley & Sons, Ltd.

A Fuzzy Methodology for Evaluation of the Liquefaction Potential

A methodolgy is presented in this paper in which geotechnical parameter uncertainty is modeled by fuzzy numbers and allowed to propagate in a deterministic model. Emphasis in this paper is placed on the liquefaction potential evaluation considering parameter uncertainty.Three deterministic models are used for liquefaction potential evaluation. For each of these models, uncertainty in soil parameters is modeled by fuzzy numbers, and liquefaction potential is analyzed. Study of historical cases using the presented methodology is conducted. Results of these case studies clearly demonstrate that uncertainty can easily be incorporated and handled in a routine liquefaction evaluation.

Soil liquefaction evaluation using shear wave velocity

A reasonably good relationship between shear wave velocity (SWV) and standard penetration resistance (SPT) of granular soils in agreement with previous studies was obtained from field tests. A similar correlation between SWV and cone penetration resistance of granular soils was also obtained. Using Seed's Standard Penetration Test (SPT)-based soil liquefaction charts, new charts of soil liquefaction evaluation based on SWV data were developed for various magnitude earthquakes.

Determination of Threshold Ground Acceleration for Soil Liquefaction Using the Strain and Stress Approaches

The evaluation of soil liquefaction using the stress approach utilizes the relative density and initial confining stress available at the layer subjected to liquefaction. The shear strain approach makes use of the shear modulus which is a more fundamental property of materials. The threshold ground acceleration values for forty layers at ten selected sites were evaluated using the stress and strain approaches. For the stress approach, the method proposed by Shibata and Teparaksa (1988) based on the concept of critical cone tip resistance was selected. For the strain approach, the method proposed by Dobry and others (1981) was employed. The threshold ground acceleration values computed using the stress approach were found to be two to four times higher than those computed using the strain approach. Several scenarios were tested in order to incorporate the effect of variations in the threshold shear strain and the ratio of (G/Gmax)t. The results of the stress and the strain methods are based on site response analyses performed using the program SHAKE91 and the input ground motions of the 1988 Saguenay earthquake.

Discussion of “Evaluation of Liquefaction by Energy Principles” by J. Ludwig Figueroa, Adel S. Saada, Liqun Liang, and Nitin M. Dahisaria

SchemaUc Local Insublilly i nitl al where D. = ultimate (residual) disturbance (Fig. 12); and A and Z =parameters that can depend on (J;, p, and 6. Here, D is plotted such that D. = 1.0, where the ultimate stress approaches zero. The values of D. are related to the observed behavior when the ultimate stress (strength) approaches a value greater than zero. The values of critical disturbance, De' marked in Fig. 12, indicate points where the rate of change in D experiences a significant change (increase), and the points are identified by the stationary conditions based on the first and second derivatives of D with respect to £0 (Desai and Toth (in press, 1994). The disturbance D can be defined in terms of observed stresses, volume, or nondestructive (ultrasonic) velocities [Desai (1995) and Desai and Toth (in press, 1994)]. Here, for the cyclic behavior, a simplified form of disturbance is defined with respect to the peak values of the shear stresses (Fig. 4). Accordingly

Closure to “Evaluation of Liquefaction by Energy Principles” by J. Ludwig Figueroa, Adel S. Saada, Liqun Liang, and Nitin M. Dahisaria

Closure to “Evaluation of Liquefaction by Energy Principles” by J. Ludwig Figueroa, Adel S. Saada, Liqun Liang, and Nitin M. Dahisaria

Discussion of “Evaluation of Liquefaction by Energy Principles” by J. Ludwig Figueroa, Adel S. Saada, Liqun Liang, and Nitin M. Dahisaria

Discussion of “Evaluation of Liquefaction by Energy Principles” by J. Ludwig Figueroa, Adel S. Saada, Liqun Liang, and Nitin M. Dahisaria

Oscillatory soil response and liquefaction in an unsaturated layered seabed

AbstractThe subject of wave‐induced soil response in a real seabed has attracted the attention of geotechnical and coastal engineers over the last three decades, for which several basic theories have been developed. However, the evaluation of soil liquefaction has not been attempted theoretically in a seabed with multiple sub‐layers, in which homogeneity in soil properties can be assumed within each layer. In this study, a semi‐analytical approach is presented for obtaining solutions for the pore pressure and effective stresses in a non‐cohesive layered seabed of finite thickness subject to a system of three‐dimensional waves. Based on the numerical results for a layered seabed, influences of soil characteristics (relative layer thickness, permeability ratio and shear modulus) on seabed responses are described. Special attention is given to the effect of placing a coarser material as a top layer for protecting an underlayer of finer sediment. Although only a three‐layered seabed is explicitly solved in this study, the procedure outlined can readily be extended to a multi‐layered soil system. The three‐dimensional solutions can also be applied to the two‐dimensional progressive or standing wave systems.