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高庙子膨润土已被确定为我国高放废物地质处置的首选缓冲/回填材料,进行其力学特性及应用模拟研究对合理设计处置库具有十分重要的意义。考虑膨胀效应的UH模型是在超固结非饱和土本构模型(非饱和土UH模型)的基础上提出的,因引入了土体团粒的吸水膨胀作用,使其适用于非饱和膨润土。基于有限元软件ABAQUS的二次开发平台,利用Fortran语言编制模型的UMAT(user-difined material)材料子程序,进行了考虑膨胀效应UH模型的有限元实现。然后针对高放废物处置概念模型,利用编制的模型子程序对高放废物处置系统进行了三维有限元模拟,并对渗流场和应力场的演化规律进行了初步探究。模拟结果显示处置系统中膨润土的内应力增加,土体的稳定性较好,说明选择高庙子膨润土作为缓冲/回填材料的合理性,也同时验证了程序的正确性。
Gaomiaozi Bentonite has been identified as the preferred buffering / backfilling material for the geological disposal of high level radioactive waste in our country. It is of great significance to study its mechanical properties and application simulation to the rational design of the repository. The UH model considering the expansion effect is proposed based on the overconsolidated unsaturated soil constitutive model (unsaturated soil UH model), which is suitable for unsaturated bentonite because of the water-swelling effect of soil aggregates. Based on the secondary development platform of finite element software ABAQUS, the UMAT (user-difined material) subroutine of Fortran programming model was used to realize the finite element realization of the UH model considering the expansion effect. Then, according to the conceptual model of HLW disposal, a three-dimensional finite element simulation of HLW disposal system was carried out by using the developed model subroutine. The evolution of seepage field and stress field was also studied. The simulation results show that the internal stress of bentonite increases and the soil stability is good. It shows the rationality of choosing Gaomiaozi bentonite as buffer / backfill material and verifies the correctness of the program.