珠江三角洲软土触变性试验研究

Experimental study on thixotropy of soft soils in Pearl River Delta

为研究珠江三角洲软土触变特性,采用无侧限压缩试验和十字板剪切试验对珠江入海口软土开展了长达115 d的试验研究,重点分析了不同含水率和静置时间条件下,软土强度恢复演化规律。试验结果表明:珠江入海口软土具有显著的触变特性,无论是无侧限压缩试验还是十字板剪切试验,软土扰动后强度均随静置时间的增长逐渐恢复;相同静置时间条件下,软土试样强度均随含水率的增大而减小。然而,通过两种试验方法得到的软土触变强度恢复曲线不一,总体上来看,通过十字板剪切试验得到的软土触变强度高于无侧限压缩试验结果。在此基础上,结合十字板剪切试验结果,建立了可反映随含水率和静置时间影响的珠江入海口软土强度触变模型;通过实测值和计算值的对比,表明该模型可以较好地预测软土触变强度。

In order to study the thixotropic properties of soft soils in the Pearl River Delta,unconfined compression tests and vane shear tests were carried out on the soft soils in the Pearl River Estuary,lasting for 115 days.The study focuses on the strength recovery of soft soils under different water content and stewing time conditions.The results show that the thixotropic properties of soft soils in the Pearl River Estuary are significant in the unconfined compression test and the vane shear test.No matter in the unconfined test and vane shear test,the strength of the soft soils gradually recovers with increasing stewing time.At a certain stewing time,the strength of the soft soil decreases with increasing water content.However,the strength recovery curves of soft soil obtained from the two tests are different.In general,the thixotropic strength of soft soils obtained from the vane shear test is higher than the ones of the unconfined compression test.Based on the test results of the vane shear test,a thixotropic model for the strength of soft soils in the Pearl River Estuary is developed considering the effects of water content and stewing time.The calculated results are in accordance with the measured data,the validity of this model is verified.