为得到干湿循环作用下的长沙绕城高速公路粉质黏土损伤特性,基于连续损伤力学和统计理论,对土体劣化过程进行分析.在假定土体微元强度服从正态分布的基础上将干湿循环损伤变量直接耦合至统计损伤本构模型,从而推导土体在干湿循环作用下的损伤本构方程.结合长沙绕城高速粉质黏土三轴固结不排水实验,着重分析干湿循环次数对土体微元强度的影响.研究结果表明:在干湿循环作用下,长沙绕城高速公路粉质黏土统计损伤本构模型应力?应变计算曲线与实验实测结果相吻合;拟合度均在0.95以上,土体经历1次或2次干湿循环作用后,其微元强度会有一定幅值降低,而后变化幅度较小;土体微元强度离散性受干湿循环作用影响,并随循环次数增多呈增大趋势.%In order to obtain silty clay's damage characteristics of Changsha ring expressway during dry-wet cycle, soil degradation processes were analyzed based on the continuous damage mechanics and statistical theories. Assuming soil micro strength was normally distributed, dry-wet cycle damage variable was directly coupled to the statistical damage constitutive model. Then, the damage constitutive equation of soil was built under the effect of dry-wet cycle. Meanwhile, combing with the triaxial consolidated undrained test about Changsha ring expressway silty clay, the impact of dry-wet cycle on soil infinitesimal strength was analyzed. The results show that calculation results of statistical damage constitutive model about Changsha ring expressway silty clay during dry-wet cycle are accordance with the experimental results, and the degree of fitting is above 0.95. After one or two dry-wet cycle interactions, soil's infinitesimal strength will reduce to some extent, and then there will be small changes in amplitude. The discreteness of soil's infinitesimal strength is influenced by dry-wet cycle and tends to increase with cycles times.
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