冻融受荷岩石变形破坏分析

发布时间：2018-01-25 17:43

本文关键词： 损伤力学冻融循环围压数值计算　出处：《西安科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：由于寒区岩土工程规模和数量的增加,冻融灾害防治成为亟待解决的关键问题,加深对冻融岩石变形破坏特性的研究是非常必要的。本文以冻融循环与荷载共同作用下的岩石为研究对象,以连续损伤力学为基础,研究冻融循环次数和围压对岩石力学特性的影响。并借助数值计算,对经历不同冻融循环次数、不同围压条件下岩石试样的破坏过程进行模拟。基于损伤力学基本理论,利用推广后的应变等价原理,分别建立岩石在单荷载作用下和冻融荷载共同作用下的损伤演化方程和损伤本构关系,并使用岩石在常温条件下和冻融循环后的三轴压缩试验数据验证本构模型,证明了模型的合理性。当围压不变时,随着冻融次数的增加,冻融受荷总损伤变量逐渐增大,岩石强度减小,冻融循环减弱岩石的脆性,增强了其塑性;当冻融循环次数不变时,总损伤变量随围压的增大而减小,岩石的强度增加,且塑性特性明显增强。借助有限元的数值计算方法,利用热应力分析中的顺序耦合思想,模拟岩石试样的冻融循环试验和冻融后不同围压条件下的压缩试验,通过数值模拟与试验结果的对比,验证数值方法模拟冻融岩石变形破坏过程的可行性。为冻融岩石的损伤特性分析提供思路。
[Abstract]:Because of the increase of the scale and quantity of geotechnical engineering in cold region, the prevention and treatment of freeze-thaw disaster has become a key problem to be solved urgently. It is necessary to further study the deformation and failure characteristics of freeze-thaw rock. In this paper, the rock under the combined action of freeze-thaw cycle and load is taken as the object of study and based on the mechanics of continuous damage. The effects of freeze-thaw cycles and confining pressures on the mechanical properties of rock were studied. The failure process of rock samples under different confining pressures is simulated. Based on the basic theory of damage mechanics, the generalized strain equivalence principle is used. The damage evolution equation and damage constitutive relation of rock under the action of single load and freeze-thaw load are established respectively. The constitutive model is verified by the triaxial compression test data of rock at room temperature and after freeze-thaw cycle, which proves the rationality of the model. When the confining pressure is constant, with the increase of freeze-thaw times. The total damage variable of freezing and thawing increases gradually, the strength of rock decreases, and the brittleness of rock is weakened by freeze-thaw cycle, and its plasticity is enhanced. When the number of freeze-thaw cycles is constant, the total damage variable decreases with the increase of confining pressure, the strength of rock increases, and the plastic property is obviously enhanced. By using the idea of sequential coupling in thermal stress analysis, the freezing and thawing cycle tests of rock samples and compression tests under different confining pressures after freezing and thawing are simulated, and the results of numerical simulation and test are compared. The feasibility of simulating the deformation and failure process of frozen and thawed rock by numerical method is verified, which provides a way to analyze the damage characteristics of frozen and thawed rock.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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