天然沉积粉质土压缩特性研究

Compressive behavior of natural silty soils

采用自由活塞薄壁取土器自地表至深度70m取得不扰动原状粉质土样,通过一系列物理力学试验,对比分析了天然沉积粉质土与天然沉积粘性土的异同。明确了位于塑性图A线下方的粉质土的重塑压缩性状可以用孔隙指数进行归一化,其孔隙指数和固结压力的关系与基于塑性图中位于A线上方的粘性土试验数据提出的固有压缩曲线一致。但是,天然沉积粉质土的天然沉积状态线位于普通粘性土的天然沉积压缩线的上方。结果表明,天然沉积粉质土比天然沉积粘性土有更高位的结构,灵敏度更高,更易于受到取样扰动的影响。

A free piston thin wall sampler was used to obtain undisturbed specimens of natural sedimentary silty soils from ground surface to the depth of 70 m. A series of tests were performed on both the undisturbed and the remolded/reconstituted samples. The difference in physical and mechanical behavior between clayey and silty soils was discussed. The void index could be used for normalizing the compressive curves of various remolded/reconstituted silty soils, and the normalized curve of void index versus applied stress for remolded/reconstituted silty soils lying below the A-line was consistent with the intrinsic compression line proposed by Burland based on clayey soils lying above the A-line. But the curve of natural silty soils lay above the sedimentation compression line in terms of the in-situ void index versus effective overburden pressure. The sedimentation compression line was proposed for natural ordinary clayey soils with a normally consolidated history. The above results indicate that natural silty soils are more easily disturbed during sampling and handling than ordinary natural clayey soils due to high sensitivity.