Liquefaction Susceptibility Of Fine-Grained Soils Research Articles

Centrifuge modeling of seismic response of normally consolidated deep silt deposit

Observations from recent earthquakes in Taiwan and Turkey have shown that current methodology to determine the liquefaction susceptibility of fine-grained soils is no longer sufficient to quantify seismic hazard, and that low plasticity fine-grained soils such as silts could also cause adverse effects on the performance of civil infrastructures. It is very important to understand the dynamic behavior of silt deposit because most of coastal areas, where there are many ongoing construction activities, consist mainly of silts, which might be vulnerable to earthquake loadings. This paper presents the experimental results of centrifuge tests on reconstituted specimen to investigate the dynamic response of normally consolidated deep silt deposit in Seattle area. The experimental sequence and preparation of the artificial silt deposit are described in detail. The recorded downhole accelerations are utilized to identify variation of shear modulus and damping ratio with shear strain amplitude via inverse analysis techniques applied to dense instrumentation arrays in a dynamic centrifuge model test.

Erratum for “Closure to ‘Assessment of the Liquefaction Susceptibility of Fine-Grained Soils’ by Jonathan D. Bray and Rodolfo B. Sancio”

Erratum for “Closure to ‘Assessment of the Liquefaction Susceptibility of Fine-Grained Soils’ by Jonathan D. Bray and Rodolfo B. Sancio”

Insight into the effects of clay mineralogy on the cyclic behavior of silt–clay mixtures

Results of a systematic testing program showed that the cyclic behavior of silt–clay mixtures is greatly influenced by the dominant clay minerals in the mixture. In particular, it was demonstrated that given the same amount of clay/clay mineral and/or same value of plasticity index, the montmorillonitic soils have the highest cyclic strength, followed by the illitic soils, and then by the kaolinitic soils. Moreover, the rate of increase in cyclic strength with increasing % clay mineral and PI is again the highest in the montmorillonitic soil, lowest in the kaolinitic soil and intermediate in the illitic soil. Therefore, without considering clay mineralogy, the % clay fraction, % clay mineral and plasticity index are unreliable indicators of the liquefaction susceptibility of fine-grained soils. The differing adhesive bond strength each clay mineral develops with the silt particles is deemed to largely explain the observed differences in the response of the three different soil mixtures to cyclic loading.

Cyclic Behavior of Fine-Grained Soils at Different pH Values

The effects of pH on the liquefaction susceptibility of fine-grained soils were examined by performing undrained cyclic ring-shear tests on artificial mixtures and a natural soil under different pH conditions. Solutions of diluted sulphuric acid (H2SO4) and dissolved sodium hydroxide (NaOH) were used to create acidic and alkaline environments, respectively, while distilled water was used as a reference liquid. Low plasticity kaolin and illite-sand mixtures and a medium plasticity bentonite-sand mixture were selected to investigate the influence of plasticity and clay mineralogy on the pH-dependent response of soil to cyclic loading. The results showed that the effects of pH were more pronounced for the medium plasticity mixture, and depended greatly on the mineralogy of clay fraction. For example, in an acidic medium, the kaolin-sand mixture became slightly more resistant to liquefaction while the illite-sand mixture became more susceptible to liquefaction. The bentonite-sand mixture was observed to be the most sensitive to changes in pH environment. While resistant to liquefaction in distilled water, it rapidly liquefied in acidic and alkaline mediums. Cyclic behavior of a medium plasticity soil, which was collected from an earthquake-induced landslide, was also affected by changes in pH. Although being overall resistant to liquefaction regardless of pH, it decreased its cyclic strength in both acidic and alkaline environments. Based on the available literature and the obtained results, an attempt was made to explain the influence of pH on the undrained cyclic behavior of fine-grained soils.

Discussion of “Assessment of the Liquefaction Susceptibility of Fine-Grained Soils” by Jonathan D. Bray and Rodolfo B. Sancio

Discussion of “Assessment of the Liquefaction Susceptibility of Fine-Grained Soils” by Jonathan D. Bray and Rodolfo B. Sancio

Discussion of “Assessment of the Liquefaction Susceptibility of Fine-Grained Soils” by Jonathan D. Bray and Rodolfo B. Sancio

Discussion of “Assessment of the Liquefaction Susceptibility of Fine-Grained Soils” by Jonathan D. Bray and Rodolfo B. Sancio

Closure to “Assessment of the Liquefaction Susceptibility of Fine-Grained Soils” by Jonathan D. Bray and Rodolfo B. Sancio

Closure to “Assessment of the Liquefaction Susceptibility of Fine-Grained Soils” by Jonathan D. Bray and Rodolfo B. Sancio

Assessment of the Liquefaction Susceptibility of Fine-Grained Soils

Observations from recent earthquakes and the results of cyclic tests indicate that the Chinese criteria are not reliable for determining the liquefaction susceptibility of fine-grained soils. Fine-grained soils that liquefied during the 1994 Northridge, 1999 Kocaeli, and 1999 Chi-Chi earthquakes often did not meet the clay-size criterion of the Chinese criteria. Cyclic testing of a wide range of soils found to liquefy in Adapazari during the Kocaeli earthquake confirmed that these fine-grained soils were susceptible to liquefaction. It is not the amount of “clay-size” particles in the soil; rather, it is the amount and type of clay minerals in the soil that best indicate liquefaction susceptibility. Thus plasticity index (PI) is a better indicator of liquefaction susceptibility. Loose soils with PI 0.85 were susceptible to liquefaction, and loose soils with 12 0.8 were systematically more resistant to liquefaction. Soils with PI>18 tested at low effective confining stresses ...

Discussion of “Subsurface Characterization at Ground Failure Sites in Adapazari, Turkey” by Jonathan D. Bray, Rodolfo B. Sancio, Turan Durgunoglu, Akin Onalp, T. Leslie Youd, Jonathan P. Stewart, Raymond B. Seed, Onder K. Cetin, Ertan Bol, M. B. Baturay, C. Christensen, and T. Karadayilar

A discussion of an article with the aforementioned title, published in this journal in July 2004 is presented. The discussers reevaluate some of the cases in the original paper to define the causes of the ground failures other than liquefaction. The properties for the failure of building sites F, C, and G are reviewed to consider bearing-capacity degradation calculations as a possible cause for the ground failures. While there is no current tool or technique to evaluate the liquefaction susceptibility of fine-grained soils, it may be misleading to claim it as the main cause of damage and destruction.

Subsurface Characterization at Ground Failure Sites in Adapazari, Turkey

Ground failure in Adapazari, Turkey during the 1999 Kocaeli earthquake was severe. Hundreds of structures settled, slid, tilted, and collapsed due in part to liquefaction and ground softening. Ground failure was more severe adjacent to and under buildings. The soils that led to severe building damage were generally low plasticity silts. In this paper, the results of a comprehensive investigation of the soils of Adapazari, which included cone penetration test (CPT) profiles followed by borings with standard penetration tests (SPTs) and soil index tests, are presented. The effects of subsurface conditions on the occurrence of ground failure and its resulting effect on building performance are explored through representative case histories. CPT- and SPT-based liquefaction triggering procedures adequately identified soils that liquefied if the clay-size criterion of the Chinese criteria was disregarded. The CPT was able to identify thin seams of loose liquefiable silt, and the SPT (with retrieved samples) allowed for reliable evaluation of the liquefaction susceptibility of fine-grained soils. A well-documented database of in situ and index testing is now available for incorporating in future CPT- and SPT-based liquefaction triggering correlations.