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对原状温州黏土进行了三轴不排水循环剪切试验,系统分析了黏土在循环剪切过程中应变和孔压的累积特性以及加载频率的影响。考虑到天然黏土不等向固结历史的影响,试验土样在循环剪切前均先K0固结至原位应力状态。研究表明,对于K0固结软黏土,以剪应变累积曲线出现拐点作为循环破坏标准较为合适,此拐点对应的单幅破坏峰值剪应变εs,tp大小基本恒定为3%,与加载频率、循环偏应力幅值等因素无关;循环荷载幅值一定时,荷载持续时间t对黏土的循环剪切性状起控制作用,可综合反映加载频率和振次的影响。根据黏性不排水循环累积效应与静力蠕变过程的相似性,按静力蠕变等效的思路,采用建立的各向异性弹黏塑性本构模型对其进行模拟分析,并通过试验验证了此流变等效方法的有效性。
Three-axis undrained cyclic shear tests were carried out on the intact Wenzhou clay. The cumulative characteristics of strain and pore pressure during cyclic shear and the influence of loading frequency were systematically analyzed. Taking into account the unequal consolidation history of natural clay, the tested soil samples were first consolidated to the in situ stress state before cyclic shear. The results show that for K0 consolidated soft clay, it is more appropriate to use the inflection point as the criterion for cyclic failure in the cumulative curve of shear strain. The peak shear strain εs and tp corresponding to this inflection point are basically constant at 3%, which is consistent with the loading frequency, Stress amplitude and other factors. When the cyclic loading amplitude is constant, the load duration t plays a controlling role on the cyclic shear properties of clay, which can comprehensively reflect the influence of loading frequency and vibration frequency. According to the similarities between the accumulative cumulative effect of undrained cyclic viscosity and the static creep process, according to the idea of static creep equivalent, the established anisotropic elastic visco-plastic constitutive model is simulated and verified by experiments The effectiveness of this rheological equivalence method.