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实地调查，以进一步检查在对1999年土耳其科凯利地震进行震后勘察期间所作的重要观察。位于伊兹米特湾沿岸的家乐福购物中心综合体的饱和细粒土层中发生了强度损失、软化和沉降等液化型行为，距离断层破裂部分约5公里。地震发生时，购物中心的建设正在进行中，主楼下面的土壤已经进行了改良，以减轻土壤液化的影响，而大部分场地和周围的所有房产仍然位于未经改良的土壤上。在两个粉土/粘土层(ML/CL)和一个高塑性粘土层(CH)中观察到了显著的沉降。这些细粒材料，特别是CH土壤的循环强度损失是意想不到的，因为根据目前的液化指南，它们是不可液化的。如果沉降数据被发现是有效的，就会有重要的影响，因为可能会表明，当前的指南不是这些材料的抗震性能的可靠预测因子。对家乐福购物中心综合体的土壤液化进行进一步检查的目的是：1)确认之前的观察结果，2)收集易腐烂的数据，以便为工程界完整地记录这一独特的场地，并允许未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，在数据丢失之前对土壤进行采样是当务之急。

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.