多年冻土区新型框架热锚管支护边坡稳定性分析

With the construction of large-scale project and global warming, freeze-thaw landslide is increasing frequent in the cold regions, In addition, the special physical properties of frozen soil, which brings enormous challenges to the disaster prevention of slopes in cold regions. Based on the concept of cooling and protecting frozen soil, a new type of frame thermal anchor pipe supporting structure with active cooling and anchoring is proposed. There is a complex physical and mechanical interaction between the new structure and slope. The traditional method is not suitable for the stability analysis of structure supporting slope. Therefore, facing the problem of its stability, according to the mechanism of the permafrost slope freeze-thaw and the working principle of structure, identifying the key affecting factors of stability; Then, using the combination method of in-depth theoretical analysis, indoor testing and numerical simulation to research the force transfer characteristics of the thermal anchor pipe-frozen soil interface, the heat exchange cooling and anchorage performance on the stability impact of new structural supporting slope. The specific content conclude: ①carrying out anchorage pull test, establishing the interface model of the anchor pipe-frozen soil; ②establishing the nonlinear slip composite unit of the anchor pipe-soil considering the temperature effect in interface; ③giving the multi-field coupled intelligent stability analysis method for new structure-frozen slope; The research results provide theoretical basis for the engineering of new structure, and have important scientific and practical value for the anchoring projects in frozen region.

随着大规模寒区工程建设和全球气候变暖，冻融滑坡灾害频繁发生且逐年增加，以及冻土的特殊物理性质给寒区边坡工程灾害治理带来巨大难题。基于冷却保护冻土理念，提出具有主动降温和锚固功能的新型框架热锚管支护结构。该结构与边坡土体间发生着复杂的物理力学作用，传统的方法不能胜任该结构锚固边坡的稳定性分析。因此，针对其稳定性问题，根据多年冻土边坡冻胀、融滑失稳机理和结构工作原理，查明影响稳定性的关键因素，通过深入理论分析、室内试验及数值模拟相结合手段，研究热锚管-冻土界面摩阻和传力特性、换热降温及支锚性能对该新型结构锚固边坡稳定性的影响。具体内容为：①开展锚土拉拔试验，建立锚管-冻土界面剪切模型；②建立考虑温度效应的锚管-冻土界面非线性滑移组合单元模型；③给出新型结构-冻土边坡多场耦合的智能稳定性分析方法；成果为该新型结构的工程实践提供理论依据，对冻土区锚固工程建设具有重要科学意义和实用价值。

针对工程建设扰动和气候暖诱发的冻土边坡滑塌失稳问题，围绕具有主动降温和锚固功能的新型框架热锚管支护多年冻土边坡的稳定性，采用试验、理论和数值分析相结合的手段，开展的主要内容及成果包括：基于微元体锚-土界面性能测试方法和土体-水泥浆界面剪切试验两种方法，得到了锚固体-土体界面剪应力-位移曲线以及温度是影响界面剪切强度的主要因素，提出了考虑温度效应的冻土-锚固体界面剪应力-位移本构模型。基于荷载传递法，引入界面剪切模型，建立了冻土中锚杆荷载传递方程，采用有限差分法进行求解，得到了锚杆荷载分布规律，结合不同温度作用下土体中锚杆拉拔试验，进一步对比验证和揭示了冻土锚杆承载特性。建立了锚杆与岩土体时效变形耦合效应的并串组合模型，得到了锚固力损失规律计算方法。建立考虑框架-热锚管-土体协同变形的结构冻胀计算模型，得到了约束冻胀作用下框架内力分布规律。基于热锚管换热机理和水热力耦合理论，建立了大气-框架热锚管-边坡系统耦合分析模型，采用有限元-有限差分相结合的方法进行了求解，得到了冻融作用下，新型支护结构锚固边坡的温度、水分和变形规律以及锚固结构的内力和变形。给出了水热力耦合有限元极限平衡联合的稳定性评价方法。基于主动保护冻土理念，研发了2种主动制冷锚杆和1种自降温抗滑桩，搭建了顶盖可开启的大型冻融模型箱。研究成果为新型框架热锚管支护冻土边坡提供了理论支撑，为冻土边坡灾害治理提供了新技术，制作的冻融模型箱为后续研究和学科发展奠定了基础平台。