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武汉老黏性土是一种结构性强、超固结、裂隙节理发育的硬塑黏土。从武汉市汉阳某基坑取得原状土样,进行一维固结试验、无侧限抗压试验和常规三轴不排水剪等试验,然后制备重塑土样做对比测试,以揭示老黏性土的结构性。对比相同条件下的三轴试验结果发现:重塑土的黏聚力明显低于原状土,剪切过程中原状土试样普遍表现为应变软化而重塑试样则为应变硬化;原状样比重塑样更容易出现剪胀现象,并且原状土样在较低围压下固结时,其剪切后期均出现负孔隙水压力,表现出明显的剪胀现象。
The old clayey soil in Wuhan is a kind of hard plastic clay with strong structural, super-consolidated and fractured joints. The unmodified soil samples were obtained from a foundation pit in Hanyang, Wuhan. One-dimensional consolidation tests, unconfined compression tests and conventional three-axis undrained shear tests were conducted. Then, the remolded soil samples were prepared for comparison test to reveal the old viscosity Soil structure. Comparing the triaxial test results under the same conditions, it is found that the cohesion of the remolded soil is obviously lower than that of the undisturbed soil. In the process of shearing, the undisturbed soil samples generally show strain softening and the remolded sample is the strain hardening. The remolded samples are more prone to dilatancy, and when intact soil samples are consolidated under lower confining pressure, negative pore water pressure appears at the later stage of shearing, showing obvious dilatancy.