花岗岩残积粘性土加、卸荷抗剪强度分析

以广州地区花岗岩残积粘性土为研究对象,通过击样法制备特定含水量试样,在不同压力下进行固结加、卸荷试验,对比分析试验数据,初步研究加、卸荷状态下花岗岩残积粘性土的抗剪强度变化,探寻先期固结压力、含水量与抗剪强度间规律。重塑残积土抗剪强度随含水量增加而减小;在先期固结压力相同的条件下,卸荷相对加荷试验条件下的土体强度显著减小,且减少值随残积土含水量的增加而逐渐减小,故在基坑开挖等卸荷工程项目中,应充分考虑卸荷对土体抗剪强度的影响,在卸荷工程中采用土体卸荷抗剪强度指标更符合工程实际。

Loading and unloading shear strength analysis of granite residual cohesive soil

The grainte residual cohesive soil in Guangzhou area is studied in this paper,the right water content samples are prepared by compaction tests.The loading and unloading shear strength is obtained under different consolidation pressure.The shear strength change of loading and unloading is contrasted and analyzed in this paper to seek the law within the pre-consolidation pressure,water content and shear strength.The shear strength of the granite residual cohesive soil increases with the increasing of the water content.The unloading shear strength reduced evidently,which is compared with loading shear strength under the same pre-consolidation pressure.And the reduction decreases gradually with the increasing of the water content,so we should fully consider the effect of unloading to the granite residual cohesive soil in the foundation pit excavation and other unloading engineering projects.Using the unloading shear strength index is more in agreement with the engineering reality in the unloading engineering projects.