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通过不同固结、剪切路径,对广州典型软土进行了卸荷抗剪强度试验,试验结果显示,不同的试验方法得到不同抗剪强度参数。不同试验方式下,土样卸荷后的抗剪强度指标都低于加荷下的抗剪强度指标;对基坑工程而言,采用DCU(侧向卸荷三轴试验)更符合实际情况,鉴于该试验方法较难,可采用DGK(先预压固结后卸荷至不同固结压力再进行快剪试验)得到的指标来代替。试验结果还表明:卸荷状态下土体应力应变曲线仍为双曲线形式,且曲线为加工硬化型;在相同的围压下,卸荷强度小于加荷强度;初始切线卸荷模量小于初始切线加荷模量,即用加荷下的加荷模量来代替卸荷下的卸荷模量将会使得工程偏于危险。
Through different consolidation and clipping paths, unloading shear strength tests were carried out on typical soft soils in Guangzhou. The test results show that different test methods have different shear strength parameters. Under different test methods, the shear strength index of unloading soil samples are lower than the shear strength index under load; for the foundation pit project, DCU (lateral unloading triaxial test) is more in line with the actual situation, In view of the test method is more difficult, you can use DGK (after unloading pre-consolidation pressure to different consolidation pressure and then quickly shear test) to get the indicators instead. The test results also show that the stress-strain curve of the soil under unloading is still hyperbolic, and the curve is work hardening. Under the same confining pressure, the unloading strength is less than the loading strength. The initial trimming unloading modulus is smaller than the initial Tangential loading modulus, that is, the loading modulus under load to replace the unloading unloading modulus will make the project more dangerous.