Preliminary Investigation of Unexpected Liquefaction-type Behavior of Fine-Grained Soils in Turkey

这笔用于探索性研究的小额赠款支持一项实地调查，以进一步审查1999年土耳其科贾埃利地震震后勘测期间的重要观测结果。 液化型行为的形式强度损失，软化和沉降发生在饱和细粒土层中的家乐福购物中心综合体位于沿着伊兹米特湾，约5公里的断裂部分。 地震发生时，购物中心正在建设中，主楼下面的土壤已经得到改善，以减轻土壤液化，而大部分场地和周围的所有财产，仍然在未经改良的土壤上。 在两个粉土/粘土（ML/CL）地层和一个高塑性粘土地层（CH）中观察到显著的沉降。 在这些细粒材料，特别是CH土壤，循环强度损失，是出乎意料的，因为它们不被认为是可液化的现行液化准则。 如果发现沉降数据是有效的，则会产生重要的影响，因为这可能表明，当前的指南并不能可靠地预测这些材料的地震行为。对家乐福购物中心综合体土壤液化的进一步研究旨在：（1）确认先前的观察结果，2）收集易损坏的数据，以便为工程界提供这一独特场地的完整文件，并允许将来进行更全面的研究。 这项研究将涉及现场测试和取样、循环三轴测试和分析工作。 家乐福购物中心正在迅速发展，必须在数据丢失之前对土壤进行采样。

This small grant for exploratory research supports a field investigation to further examine important observations made during a post-earthquake reconnaissance of the 1999 Kocaeli Earthquake in Turkey. Liquefaction-type behavior in the form of strength loss, softening, and settlement occurred in saturated fine-grained soil strata at the Carrefour Shopping Center complex located along Izmit Bay, about 5 km from the ruptured portion of the fault. Construction of the shopping center was underway when the earthquake struck, and the soil beneath the main building had been improved to mitigate soil liquefaction, while most of the site, and all of the surrounding properties, remained on unimproved soil. Significant settlements were observed to occur in two silt/clay (ML/CL) strata and one high-plasticity clay stratum (CH). Cyclic strength loss in these fine-grained materials, especially the CH soils, is unexpected, as they are not considered liquefiable by current liquefaction guidelines. If the settlement data is found to be valid, there are important implications, as it may be shown that current guidelines are not reliable predictors of the seismic behavior of these materials.This further examination of the soil liquefaction at the Carrefour Shopping Center complex is intended to: 1) confirm the previous observations, and 2) gather perishable data that will permit complete documentation of this unique site for the engineering community and allow a future, more comprehensive study. The study will involve field testing and sampling, cyclic triaxial testing, and analytical work. The Carrefour Shopping Complex is being rapidly developed and it is imperative to sample the soils before the data is lost.