偏压固结下碱渣土循环累积孔压及强度弱化规律研究

Study on cyclic cumulative pore pressure and strength evolution of soda residue soil under anisotropic consolidation

碱渣是氨碱法制纯碱时排出的固体废弃物,经适当的加固处理后作为工程填垫土可以有效解决占地和污染问题。碱渣土的力学性质不稳定,在循环荷载作用下强度会发生明显弱化,导致承载力大幅降低。以天津港地区回填碱渣土为研究对象,开展了系列动三轴试验,以固结围压、动应力比和偏压固结比为试验变量,研究了不同应力组合下碱渣土中循环累积孔压发展规律以及循环后碱渣土不排水强度演化规律。基于等效超固结模型,引入强度弱化系数β,建立了考虑偏压固结比和动应力比影响的碱渣土循环强度弱化模型;引入强度提升系数α,建立了考虑偏压固结过程和循环加载过程耦合影响的碱渣土强度演化模型,并通过试验数据验证了模型的正确性。

Soda residue(SR)is a kind of solid wastes produced in the process of soda with the method of ammonia-soda.As a ground backfill soil,SR can effectively solve the problems of land occupation and pollution after appropriate reinforcement and treatment.However,because of the poor stability of physical and mechanical properties,the material strength of SR would be weaken obviously under the action of cyclic loading such as mobile machinery loading,which will reduce the bearing capacity of SR foundation.In this study,dynamic triaxial compression tests were performed on the undisturbed SR derived from Tianjin Port.Then,the cyclic cumulative pore pressure variation and undrained shear strength variation of SR under different stress conditions were discussed.Based on Yasuhara equivalent overconsolidation model,a cyclic strength weakening model of SR considering the influence of anisotropic consolidated ratio and dynamic stress ratio was established by using strength weakening coefficientβto quantify the weakening effect of cyclic loading on the strength of material.On this basis,a strength evolution model of SR considering the coupling effect of anisotropic consolidation process and cyclic loading process was established by using strength enhancement coefficientαto quantify the effect of anisotropic consolidation process on the strength of material.The accuracy of this model was validated by comparing the experimental measurements with the model calculation results.