单轴压缩固化泥炭土的弹塑性损伤模型试验研究

为了研究固化泥炭土的力学性能,将机制砂作为填充材料,水泥和磷石膏作为胶结材料,针对昆明泥炭土开展了一系列固化试验。根据固化土体的无侧限抗压强度试验和单轴循环加-卸载试验,讨论了泥炭土在不同水泥掺量和磷石膏掺量下的固化效果。基于损伤理论和应变等效性假设,建立了单轴压缩状态下固化泥炭土的弹塑性损伤模型。研究结果表明:固化泥炭土抗压强度随水泥掺量的增加而增大,同时随着磷石膏掺量的增加,强度增长速率表现为先增大后减小的趋势。固化泥炭土的应力-应变滞回曲线呈下部不闭合的新月形,且在塑性开始和接近破坏阶段不闭合区域面积较大,说明这两个阶段产生较大的能量损耗。最后,考虑水泥掺量和磷石膏掺量的影响,根据试验结果采用曲线拟合的方法,得到了固化泥炭土弹塑性损伤本构模型的各项参数。

Experimental Study on Elasto-Plastic Damage Model of Stabilized Peaty Soil under Uniaxial Compression

In order to study the mechanical properties of stabilized peaty soil, a series of stabilization tests were carried out with machine-made sand as filling material, cement and phosphogypsum as cementing material. Based on the unconfined compressive stength test and uniaxial cyclic loading and unloading test, the stabilized effect of peaty soil was discussed under the different content of cement and phosphogypsum. According to the damage theory and the strain equivalence hypothesis, an elasto-plastic damage model of stabilized peaty soil was established under uniaxial compression. The results show that the compressive strength of stabilized peaty soil increases with the increase of cement content, and the strength growth rate increases first and then decreases with the increase of phosphogypsum content. The stress-strain hysteretic curve of stabilized peaty soil presents a crescent shape with unclosed bottom, and the unclosed areas of hysteretic curve at the beginning of plasticity and near failure stages are larger than that of other cycles, which indicates that more energy loss occurs in these two stages. Finally, considering the effects of cement content and phosphogypsum content, the parameters of the elasto-plastic damage constitutive model of stabilized peaty soil are obtained by curve fitting method according to the test results.