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 shearing paths, unloading shear strength tests were carried out on typical Guangzhou soft soil. Different shear strengths were obtained through different test methods. The unloading shear strength parameters were lower than loading shear strength parameters. For foundation pit engineering, the DCU (lateral unloading triaxial test) is suitable for the actual situation. Nevertheless owing to its difficulty, the DGK (preloading consolidation, followed by unloading to different consolidation pressures, and quick shear test in subsequence) can be employed instead. The test also showed that the stress-strain curve with work hardening was still hyperbola under unloading condition. Unloading shear strength was smaller than loading shear strength when given the same confining pressure. Initial tangential unloading modulus was smaller than initial tangential loading modulus, therefore, when the loading modulus is used instead of the unloading modulus, the project is prone to be in hazard.