冻融循环条件下覆盖型边坡破坏形式机理分析及冻融界面与滑动面位置关系研究

Failure Mechanism Analysis of Covered Slopes Under Freeze-Thaw Cycles and Relationship Between Freeze-Thaw Interface and Sliding Surface

摘要:

为缓解高海拔冻土边坡病害对交通工程的威胁,揭示高海拔冻土边坡在冻融循环作用下的失稳机理,以川西地区6个覆盖型边坡为研究对象,基于水热耦合理论,利用COMSOL Multiphysics数值模拟计算软件,对这6个边坡进行考虑冬季昼夜温差的冻融循环模拟,分析边坡水热场时空变化规律,总结边坡破坏形式,找出边坡冻融界面与滑动面的位置关系。结果表明:冻融循环主要影响冻土边坡浅层土体;边坡经过数次冻融循环后,土体在某一深度范围内的含水率高于其他深度,坡体内形成聚水区;所研究的6个覆盖型边坡共总结出5种破坏形式,分别是边坡浅层融土滑塌、边坡浅层融土蠕移、边坡浅层融土挤胀、凸形坡浅层融土滑塌、凹形坡浅层融土滑塌;在冻融循环作用下,覆盖型边坡冻融界面位置要深于滑动面。

Abstract:

To mitigate the threat of permafrost slope hazards to transportation engineering in high-altitude regions, and reveal the slope instability mechanisms under freeze-thaw cycles, six covered slopes in western Sichuan are taken as research objects. Based on the hydrothermal coupling theory, freeze-thaw cycle simulation considering diurnal temperature variation in winter is carried out for the six slopes using COMSOL Multiphysics numerical simulation software, and the spatio-temporal variation of hydrothermal field is analyzed. The failure modes of slope are summarized, and the positional relationship between the freeze-thaw interface and the sliding surface is found. The results show that the freeze-thaw cycles mainly affect the soil in the shallow layer of frozen soil slopes. After the slopes are subjected to several freeze-thaw cycles, the moisture content of the soil in a certain depth range is higher than those in other depths, and a water-gathering zone is formed in the slope. Five kinds of slope failure modes are identified from the six covered slopes, which are slope shallow melt soil collapse, slope shallow melt soil creep, slope shallow melt soil extrusion, convex slope shallow melt soil collapse and concave slope shallow melt soil collapse. Under freeze-thaw cycles, the freeze-thaw interface of covered slope is located deeper than the sliding surface.