川藏交通廊道冰碛土滑坡渗流特性及其热-水-力耦合机制

In Sichuan-Tibet transport corridor, moraine soil has a unique seepage and structural characteristics, and formed under tectonic and glacier movements conditions. moraine slopes feature a complex mechanism of temperature - seepage - stress and the coupling of soil - water phase transition under the influence of global warming and rain and heat cooperation conditions, which is not well documented yet, as a result, scientific prediction of instability of moraine slopes is difficult. Therefore, it is urgent to carry out systematic researches on instability mechanism of moraine slopes..In this proposal, the Pallongzangbou River basin is selected as the target area, based on the characteristics of permeability and the process of coupling thermal-hydro-mechanic, the mechanism of moraine slopes instability is explored in terms of theoretical analysis, physical model test and field observation, to study the hydraulics and mechanical characteristics of the unsaturated infiltration in the moraine soil. Based on the multi-physics analysis and seepage erosion constitutive model, the stability model of the moraine landslide stability and the multi-parameter critical thresholds index are established, and the temperature - seepage - erosion - stress - coupled constitutive equation of the moraine slope is established. Numerical simulation analysis was carried out subsequently, and comparison with model test and field observation data to carry out calibration and verification; This research is expected to solve the key scientific problems of the micro-mechanics mechanism of moraine slopes instability and provide a new technical framework for the stability evaluation and forecasting of the special moraine landslide in Sichuan-Tibet transport corridor and serve the national policy of "the Belt and Road".

川藏交通廊道构造运动、冰雪活动强烈，分布的冰碛土具有独特的渗流和结构特征。受全球变暖和雨热同期影响，冰碛土滑坡失稳的温度-渗流-应力以及水土相变耦合机制复杂，目前认识尚不深入，实施科学预测困难，因此亟待开展系统、深入的机理研究。本项目以川藏交通廊道帕隆藏布流域为靶区，针对冰碛土非饱和优先流渗流特征其诱发冰碛土滑坡的热-水-力耦合过程，通过理论分析、物理模型试验和现场观测交合研究方法，探明雨热变化诱发冰碛土非饱和优先流入渗的热力、水力及土力学特性；建立冰碛土滑坡失稳的温度-渗流-侵蚀-应力全耦合本构方程，并开展数值模拟和物理模型及现场观测检验修正；进一步构建基于多场耦合及渗流侵蚀本构的冰碛土滑坡稳定性预测模型及预警多参数阈值体系；以期解决冰碛土滑坡失稳的微观渗流-力学机理的关键科学问题，为川藏交通廊道特殊冰碛土滑坡的稳定性评价和预测提供新的技术框架，服务“一带一路”国家战略。

川藏交通廊道所处藏东南地区第四纪冰碛堆积物巨厚，海洋性冰川发育，区域性降雨丰沛。在气候变化背景下，该地区气候上具有高温和暴雨成为诱发大型冰碛土滑坡的主要因素，同时，雨热同期作用下，冰碛土滑坡转化为泥石流，形成滑坡-泥石流灾害链，使得冰碛土滑坡-泥石流灾害链时空延拓和规模放大，严重威胁川藏交通廊道重大工程的建设运营和人民生命财产安全。.针对以上问题，本项目以川藏交通廊道典型冰碛土滑坡灾害为靶区，结合理论分析、模型试验、现场观测，通过交合模型方法，系统研究了冰碛土滑坡的热-水-力耦合机理和滑坡堆积体热摩擦及其动力学响应机理，为冰碛土滑坡的热水力物理机制和耦合机理提供了新的认识和本构模型；通过对典型冰碛土滑坡-102滑坡、天摩沟滑坡-泥石流开展长时间序列的现场观测，反演了天摩沟冰碛土滑坡转化为泥石流灾害链的多参数预警指标体系，为川藏交通廊道监测预警冰碛土滑坡-泥石流灾害链的多参数监测预警提供了系统解决方案：结合灾害链全动力学本构模型，构建冰碛土滑坡-泥石流-堰塞湖-溃决洪水灾害链定量评价方法，针对川藏铁路可行性研究中的关键节点：格聂山滑坡-堰塞湖-溃决洪水、木格错冰湖溃决灾害链、茶隆隆巴曲冰崩/岩崩-碎屑流等重大山地灾害链，开展基于全动力过程的重大山地灾害链危险性预测和影响评估，研究成果形成了研究报告提交中铁一院和中铁二院使用和采纳，实质性支撑川藏铁路可研批复和国家立项，实质性推动川藏铁路可研批复和全面开工建设，服务国家重大工程安全。发表科研论文19篇（SCI检索9篇），授权发明专利6项，软件著作权4项，研究成果纳入“川藏交通廊道山地灾害防治理论与关键技术”并获得2020年度西藏科学技术一等奖。