多年冻土区主动冷却、减胀减震和自恢复边坡支护结构的工作机制及试验研究

With the extreme change of the global climate, freeze-thaw landslide in the permafrost regions is increasing, which not only brings security hidden danger and disaster to permafrost engineering, but also some new problems to the implementation and design of the project. In addition, earthquakes are frequent in China, so the instability hazard induced by earthquakes for slope in permafrost region cannot be ignored. Due to the complicated mechanical properties of frozen soil, stability and control of frozen soil slope under static and dynamic loading remains a difficult problem. Therefore, based on the failure mechanism under freeze-thaw effects and earthquakes, for the purpose of disaster prevention and mitigation in permafrost region, the new supporting structures of frame with pre-stressed thermal anchor pipe and ventilating-convection anchor pipe for active cooling and automatic return slope are proposed, and the mechanism, cooling, energy dissipation and damping, returning effect and analysis method are studied. The specific contents conclude:①establishing the heat transfer mathematical model of the atmosphere-anchor pipe-soil system;②establishing and solving the static and dynamic calculation model of the new slope supporting structure based on analysis of the working mechanism; ③establishing the stability analysis model of static and dynamic for the new slope supporting structure;④carrying out field and model test of the new slope supporting structure, verifying the effectiveness of the proposed structure and the correctness of analysis method, further to perfect and revise the calculation model and analysis method. The study results give a new method for the prevention and control of slope disaster in permafrost region, and provide theoretical basis for the engineering practice of the new structure. Therefore, it is of great significance to the construction of the infrastructure and the safe service in permafrost region.

随着全球气候的极端变化，寒区冻融滑坡日趋增加，既给冻土工程带来安全隐患和灾害，又给项目的实施及设计带来诸多新问题。而且我国位于地震频发地带，地震对寒区边坡诱发的失稳危害不容忽视。由于冻土的力学性质复杂，冻土区边坡在静动力作用下的稳定性和防治一直是个难题。因此，针对多年冻土边坡冻胀、融沉和地震作用下破坏机理，以冻土边坡防灾减灾为目的，提出新型框架热锚管和通风锚管的主动冷却及自恢复边坡支护结构，研究其工作机理、降温、耗能减胀减震、回位效果及分析方法。具体内容为：①建立大气—锚管—土体系统换热数学模型；②建立该新型边坡支护结构的静动力计算模型；③建立该新型边坡支护结构的静动力稳定性分析模型；④现场和室内试验，检验提出结构的有效性和分析方法的正确性，并修正与完善。本课题为多年冻土边坡灾害防治提供新方法，研究成果为该新型结构的工程实践提供理论依据，对冻土区基础设施建设和安全运营有重要意义。

（1）项目的背景. 随着全球气候的极端变化，寒区冻融滑坡日趋增加，既给冻土工程带来安全隐患和灾害，又给项目的实施及设计带来诸多新问题。而且我国位于地震频发地带，地震对寒区边坡诱发的失稳危害不容忽视。由于冻土的力学性质复杂，冻土区边坡在静动力作用下的稳定性和防治一直是个难题。.（2）主要研究内容. 针对多年冻土边坡冻胀、融沉和地震作用下破坏机理进行了研究，以冻土边坡防灾减灾为目的，研发了新型框架热锚管和通风锚管的主动冷却及自恢复边坡支护结构，研究了其工作机理、降温、耗能减胀减震、回位效果及分析方法。具体内容为：①建立大气—锚管—土体系统换热数学模型，进行了多场耦合分析；②建立该新型边坡支护结构的静动力计算模型；③建立该新型边坡支护结构的静动力稳定性分析模型；④室内试验，检验了提出结构的有效性和分析方法的正确性，并修正与完善。.（3）主要结果、关键数据. 新型结构极大提升了对流锚杆的通风能力，增大了外界冷空气与边坡内部土体之间的对流换热强度，促使多年冻土边坡内冻融交界面逐年抬升；新型边坡支护结构减弱了边坡土体的冻胀作用，能够提高多年冻土边坡的稳定性；通风冷却锚管具有较好的通风能力； 风压差是结构通风的主要驱动力，沿程阻力损失是结构主要风速损失；结构通风的最优管径比为0.4~0.7；边坡应力状态随季节冻融动态变化，新型结构作用下边坡应力发生重分布，坡面水分迁移速率增大。.（4）科学意义. 本课题为多年冻土边坡灾害防治提供新方法，研究成果为该新型结构的工程实践提供理论依据，对冻土区基础设施建设和安全运营有重要意义