饱和土冻结过程中冰透镜体形成与分层
发布时间：2018-08-27 12:09
【摘要】：随着国民经济的发展,寒区投入了大量的工程建设,研究冻土体的力学性质对寒区建设具有重大意义,建立能反映水分迁移及分凝冰形成过程的冻胀模型是冻土水-热-力三场耦合求解的关键。基于已有的耦合模型,考虑冰水界面吸力对水分驱动力的影响,推导并修改总水头的表达式;考虑未冻土区导水系数与孔隙比有关,修改渗透系数的表达式。计算结果表明:修改后的模型较原模型,孔隙结构出现不同程度的改变,进而造成冰透镜体形成和分布的差异。修改总水头后,模型的冻胀曲线呈较明显的"S"型,冰透镜体形成的厚度增加,形成冰透镜体时间提前;在未冻土区,由于渗透系数随孔隙比的减小而降低,从而导致水分迁移量大大减小,修改渗透系数后模型冻胀量较原模型明显减少,出现冰透镜体时间延后。基于模拟结果,从理论上分析冰透镜体的形成与分层,指出只要在隔水层形成之前有足够的水分迁移至冻土区,冰透镜体都可以形成,冰透镜体的分层取决于冰晶分离土颗粒贯穿形成冰透镜体的难易程度。结合达西定律,采用补水速率这一指标综合反映总水头及渗透系数对计算结果的影响,现有的分离判据可以用来解释最后一层分凝冰的形成,对于非最后一层冰透镜体,建议采用补水速率作为其形成的判断准则。
[Abstract]:With the development of the national economy, a large number of engineering projects have been invested in the cold region. It is of great significance to study the mechanical properties of the frozen soil for the construction of the cold region. A frost heaving model which can reflect the process of water migration and ice separation is the key to the coupled solution of the three fields of water thermal force in frozen soil. Based on the existing coupling model, the expression of the total water head is deduced and modified considering the influence of the suction force at the ice water interface on the water driving force, and the expression of the permeability coefficient is modified considering the relationship between the permeability coefficient and the porosity ratio in the unfrozen soil. The results show that the pore structure of the modified model is different from that of the original model, which leads to the difference of the formation and distribution of the ice lens. After modifying the total water head, the frost heave curve of the model is obviously "S", the thickness of the ice lens increases and the time of forming the ice lens is advanced. In the unfrozen soil, the permeability coefficient decreases with the decrease of the void ratio. As a result, the amount of water migration is greatly reduced, the frost heave of the model is obviously reduced than that of the original model, and the ice lens time is delayed after the permeability coefficient is modified. Based on the simulation results, the formation and stratification of ice lens are theoretically analyzed. It is pointed out that ice lens can be formed as long as there is enough water to migrate to the frozen soil region before the formation of water barrier. The stratification of ice lens depends on the difficulty of forming ice lens. In combination with Darcy's law, the effect of total water head and permeability coefficient on the calculation results is comprehensively reflected by the index of supplementary water rate. The existing separation criteria can be used to explain the formation of the last layer of condensate ice, and for the non-final layer ice lens, the existing separation criteria can be used to explain the formation of the final layer of condensate ice. It is suggested that the rate of rehydration should be used as the criterion of its formation.
【作者单位】： 四川大学水力学与山区河流开发保护国家重点实验室水利水电学院;成都理工大学地质灾害防治与地质环境保护国家重点实验室;中交第二航务工程局有限公司技术中心;中国科学院西北生态环境资源研究院冻土工程国家重点实验室;
【基金】：地质灾害防治与地质环境保护国家重点实验室开放基金资助(SKLGP2014K006) 中科院率先行动百人计划择优支持项目资助
【分类号】：TU445
本文编号：2207234
[Abstract]:With the development of the national economy, a large number of engineering projects have been invested in the cold region. It is of great significance to study the mechanical properties of the frozen soil for the construction of the cold region. A frost heaving model which can reflect the process of water migration and ice separation is the key to the coupled solution of the three fields of water thermal force in frozen soil. Based on the existing coupling model, the expression of the total water head is deduced and modified considering the influence of the suction force at the ice water interface on the water driving force, and the expression of the permeability coefficient is modified considering the relationship between the permeability coefficient and the porosity ratio in the unfrozen soil. The results show that the pore structure of the modified model is different from that of the original model, which leads to the difference of the formation and distribution of the ice lens. After modifying the total water head, the frost heave curve of the model is obviously "S", the thickness of the ice lens increases and the time of forming the ice lens is advanced. In the unfrozen soil, the permeability coefficient decreases with the decrease of the void ratio. As a result, the amount of water migration is greatly reduced, the frost heave of the model is obviously reduced than that of the original model, and the ice lens time is delayed after the permeability coefficient is modified. Based on the simulation results, the formation and stratification of ice lens are theoretically analyzed. It is pointed out that ice lens can be formed as long as there is enough water to migrate to the frozen soil region before the formation of water barrier. The stratification of ice lens depends on the difficulty of forming ice lens. In combination with Darcy's law, the effect of total water head and permeability coefficient on the calculation results is comprehensively reflected by the index of supplementary water rate. The existing separation criteria can be used to explain the formation of the last layer of condensate ice, and for the non-final layer ice lens, the existing separation criteria can be used to explain the formation of the final layer of condensate ice. It is suggested that the rate of rehydration should be used as the criterion of its formation.
【作者单位】： 四川大学水力学与山区河流开发保护国家重点实验室水利水电学院;成都理工大学地质灾害防治与地质环境保护国家重点实验室;中交第二航务工程局有限公司技术中心;中国科学院西北生态环境资源研究院冻土工程国家重点实验室;
【基金】：地质灾害防治与地质环境保护国家重点实验室开放基金资助(SKLGP2014K006) 中科院率先行动百人计划择优支持项目资助
【分类号】：TU445
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