新疆高寒山区融雪入渗作用下反倾层状岩质斜坡倾倒变形演化机理研究

The reverse-dip slope is a kind of slope which is more common in the cold mountainous area of Xinjiang. Its stability is significantly affected by long-term periodic snowmelt infiltration, which is the main factor affecting the disaster of the reverse-dip slope in Xinjiang. The existing research results of reverse-dip slopes have less consideration of the influence of snowmelt infiltration, which makes it difficult for the existing theories to solve the problem of complex geological disasters of reverse-dip slopes in cold mountainous area of Xinjiang. China has positioned Xinjiang as the core area of the Silk Road Economic Belt and has paid more attention to engineering safety, so it is necessary to study and establish a set of analytical theories and methods suitable for the deformation characteristics and stability evaluation of reverse-dip slopes in the cold mountainous area of Xinjiang. This project integrates rock mechanics and snowmelt infiltration law, establishes the snowmelt infiltration model of reverse-dip slope, and obtains its mode; it analyzes the deterioration law of mechanical parameters of rock mass under the action of snowmelt infiltration, and studies the deformation evolution characteristics of reverse-dip slope under the long-term effect of snowmelt infiltration; it improves the Goodman-Bray calculation method for the stability of the reverse-dip slope, analyzes the dynamic change characteristics of the stability of the reverse-dip slope under the action of snowmelt infiltration, and reveals its deformation evolution mechanism . It hopes to improve the stability evaluation and forecasting level of reverse-dip slope in the cold mountainous area of Xinjiang, so as to ensure the smooth implementation and safe operation of the cold mountainous area in Xinjiang.

反倾斜坡是新疆高寒山区较常见的一类斜坡，其稳定性受长期周期性的融雪入渗影响显著，融雪入渗为新疆反倾斜坡致灾的主要影响因素。现有反倾斜坡研究成果较少考虑融雪入渗的影响，导致现有理论难以解决新疆高寒山区反倾斜坡复杂地质灾害问题。鉴于国家对新疆丝绸之路经济带核心区的定位，以及对工程安全的日益重视，有必要研究建立一套适用于新疆高寒山区反倾斜坡变形特征及稳定性评价的分析理论和方法。本项目融合岩体力学与融雪入渗规律，建立反倾斜坡融雪入渗模型，得出反倾斜坡融雪入渗模式；分析融雪入渗作用下岩体力学参数劣化规律，研究融雪入渗长期作用下反倾斜坡的变形演化特征；改进反倾斜坡稳定性Goodman-Bray计算方法，分析融雪入渗作用下反倾斜坡稳定性动态变化特征，揭示融雪入渗作用下反倾斜坡变形演化机理。以期提高新疆高寒地区反倾斜坡稳定性评价与预测预报水平，保障新疆高寒山区工程顺利实施与安全运营。

本项目以新疆高寒山区反倾层状岩质斜坡为研究对象，考虑长期周期性的融雪入渗影响，综合野外地质调研与资料收集、室内外岩土实验、数值模拟等方法，揭示融雪入渗作用下反倾斜坡倾倒变形演化机理。项目主要取得如下成果：1.通过对独库公路沿线现场地质调查，共调查了40余个反倾斜坡案例，统计得出新疆高寒山区反倾斜坡坡向以南坡向为主，发育高程为1785~1923m，发育面积为8-20平方公里。2.整理高寒山区各地质分区积雪历年变化数据，通过度日模型换算融水量，采用了SPH方法建立了斜坡融雪入渗数值模型，总结了融雪入渗模式；根据CFD-DEM耦合模拟结果对反倾斜坡的变形失稳过程依次划分为了后缘张拉、剪断面贯穿坡体、倾倒变形和倾倒滑移组合变形四个阶段。3.融雪入渗对反倾斜坡的影响主要体现为水平应力、剪应力和位移场水平位移的增加，反倾斜坡失稳荷载的减小；融雪入渗会提高反倾斜坡的水平应力，导致倾倒变形过程中会产生更多的摩擦能。4.通过建立渗流场和动能完全被吸收等假设，以耗散动能阻力的反作用力为作用在岩柱上渗流力，构建渗流力和渗流速度和反倾斜坡几何形状的关系，并对渗流场进行了简化，提出了该渗流场下岩柱上的渗流力计算公式；在现有的WGB法之中考虑融雪渗流力作用，根据静力平衡和弯矩平衡重新推导建立了稳定性系数计算公式。5.融雪渗流速度和渗流范围的增大均会导致倾倒变形最小临界加速度系数的逐渐减少。渗流范围增加会使倾倒变形最小临界加速度系数呈现抛物线下降加均匀下降的下降模式。结合重力进行综合分析发现，重力荷载的增加会导致渗流作用的影响降低。渗流范围增加会使呈现抛物线下降加均匀下降的下降模式，通过上述分析融雪入渗作用下反倾斜坡稳定性动态变化特征，揭示了融雪入渗作用下反倾斜坡变形演化机理。研究成果对新疆高寒山区反倾斜坡防治具有重要理论意义。