原位十字板试验测得的软粘土灵敏度

Sensitivity of Soft Clay Obtained by Field Vaneshear Test

摘要:

收集了国内两个地区(上海和杭州湾)以及美国和日本一些地区软粘土的勘察数据，对原位十字板试验(FVT）和无侧限抗压强度试验(UCT）这两种试验所测得的灵敏度和强度进行了详细的对比与分析,并对重塑方式的影响进行了研究.发现这些地区普遍存在FVT试验得到的灵敏度要明显小于UCT试验结果，会严重低估软粘土的灵敏度；而原状土强度和重塑土强度均要大于UCT试验结果，重塑土强度尤其明显.其中重塑方式是一个重要影响因素.研究还发现FVT试验得到的重塑土强度、灵敏度与土的液性指数的相关性随着液性指数的增大而明显变差，与一些广泛使用的经验关系也差别较大.这些结果应该引起工程界的重视.

关键词:软粘土; 灵敏度; 强度; 液性指数; 原位十字板试验（FVT）; 无侧限抗压强度试验

Abstract:

Field vaneshear test (FVT) and Unconfined Compression test (UCT) are the conventional method for measuring the sensitivity of soft clay in the engineering investigation. Based on the data collected from the domestic soft clay and some regions in US and Japan, the sensitivity and strength obtained by FVT and UCT are compared in detail and the influence of remolding method is also investigated. It is found that the sensitivity obtained by the FVT test is significantly smaller than the UCT and it will underestimate the sensitivity of soft clay, FVT obtains significantly higher strength than UCT tests, especially in the remolded strength. Remolding method used in FVT is found an important influence factor. In addition, the correlations between remolded strength, sensitivity measured by FVT and liquid limit index are found not good and inconsistent with the published experiential laws. The remolded strength and sensitivity obtained by FVT are unreliable and it should be taken into consideration in evaluating the sensitivity and structural of soft clay.

Key words:soft clay; sensitivity; strength; liquid index; field vaneshear test(FVT); unconfined compression test