迄今为止,固化盐渍土的本构方程模型研究较少。本文提出了考虑冻融循环(FTC)和盐度的固化盐渍冻土损伤本构模型的建立。为了模拟固化的冻土,无侧限抗压强度试验(UCST)和固结不排水(CU)三轴剪切试验在三个环境温度(20、-10和-20°C)下进行,5岁(3、7、14、28和90d),六种盐度(0、1、2、3、4和5%),和本研究中的四个FTC(0、5、10和14次)。UCST结果表明,固化盐渍土在14日龄时的无侧限抗压强度(UCS)可以达到最大UCS的75%,基本满足工程建设要求。受盐度影响的强度损失率范围为16.2%~75.65%,而盐和冷冻条件的耦合作用放大了强度损失率。受盐度增加的影响,与解冻土壤相比,冻土的强度损失率放大了1.2到3.7倍。同样,CU三轴剪切试验表明,FTC和盐侵蚀的耦合作用放大了剪切强度的强度损失率。随着FTC的增加,杨氏模量的应变阈值逐渐向后推,这与盐度的影响相似。值得注意的是,对于盐冻耦合作用下的固化盐渍土,损伤本构模型的性能优于常规本构模型。
To date, the modelling of constitutive equations of solidified frozen saline soil have seldom been studied. This paper presented the formulation of a damage constitutive model for solidified saline frozen soil considering both freeze thaw cycles (FTCs) and salinities. To model the solidified frozen saline soil, the unconfined compression strength test (UCST) and consolidated undrained (CU) triaxial shear test were conducted under three ambient temperatures (20, -10, and -20 °C), five ages (3, 7, 14, 28, and 90 d), six salinities (0, 1, 2, 3, 4, and 5%), and four FTCs (0, 5, 10, and 14 times) in this research. The UCST results showed that the unconfined compressive strength (UCS) of the solidified saline soils at an age of 14 days can reach 75% of the maximum UCS, which basically meets the engineering construction requirements. The range of the rate of strength loss as affected by salinity was 16.2% to 75.65%, while the coupling effect of salt and frozen conditions amplified the rate of strength loss. Affected by increasing salinity, the rate of strength loss of frozen soils was magnified by a factor of 1.2 to 3.7 compared to thawing soils. Likewise, the CU triaxial shear test showed that the rate of strength loss of shear strength was amplified by the coupling effect of FTCs and salt erosion. With increased FTCs, the strain threshold of Young\'s modulus was gradually pushed backward, which was similar to the effect of salinity. Remarkably, the damage constitutive model performed better than conventional constitutive models for the solidified saline soil under the salt-freezing coupling effect.