人工水平冻结地表融沉规律的数值分析

Numerical analysis of ground thaw subsidence caused by artificial horizontal ground freezing

人工水平冻结法施工中解冻融缩与地表移动问题是其首要的环境岩土工程问题,预测和控制融沉量是冻结法能否成功实施的关键因素.通过系统数值试验研究各冻结设计参数对人工水平冻结地表融沉的影响规律.研究表明:地表最大融沉位移随冻结壁厚度、隧道半径、融沉系数的增大而增大,随隧道埋深的增大而减小,各参数对人工冻结引起地表融沉的影响效果由大到小排序依次是土体融沉系数、冻结壁厚度、隧道半径、隧道埋深.根据数值模拟结果,建议在实际工程中,采用强制解冻,跟踪注浆;减少冻结时间即减少冻结壁厚度;以降低土体中的初始含水量即减小融沉系数等措施来减小融沉及其对周围环境的影响.

The primary problem of environment geotechnical engineering in artificial horizontal freezing construction is thaw shrinking and surface movement.Predicting and controlling the thaw settlement amount of ground is the key factor for successful implementation of artificial freezing method.In this paper,systematic numerical tests were employed to study the influence of various freezing design parameters on ground thaw subsidence due to artificial horizontal freezing.The study results showed that the maximum ground thaw settlement displacement would increase with the increase of frozen wall thickness,tunnel radius and thaw settlement coefficient;decrease with the increase of tunnel depth.The results also showed that the magnitude order of influence of these parameters on the ground thaw settlement displacement was as follows：thaw settlement coefficient,frozen wall thickness,tunnel radius,and tunnel depth.According to the results of numerical simulation,it was recommended that following measures might be taken in actual engineering to reduce ground thaw settlement and its influence on surrounding environment：forced defrosting,grouting tracking;freezing time shortening to reduce frozen wall thickness;decreasing of initial water content in soil to reduce thaw settlement coefficient.