基于强度折减法的深基坑周边环境安全性评价

城市深基坑工程周边环境变形要求非常严格。因基坑开挖引起的土层扰动,可能会造成建筑物及地下管线破坏,甚至引起基坑失稳。为解决其安全性评价这一难题,吸收强度折减法的优点,提出了基于强度折减技术的深基坑周边环境安全系数的计算方法。以深基坑支护结构水平位移值达到设计控制值作为周边环境破坏的临界判据,通过不断搜索折减系数F,将岩土体材料的力学参数按F值折减代入计算模型中,达到临界条件的折减系数即为安全系数F_s。工程实例分析表明,该方法可以客观、有效地评判深基坑施工中周边环境的安全裕度,为城市深基坑施工顺利进行提供参考。

Evaluation on Environmental Safety around Deep Pit Based on Strength Reduction Theory

The deformation control around urban deep pit is strict.Foundation pit excavation may cause disturbance to the soil,and bring damage to the building and underground pipe,even the stability of foundation pit can be lost.Taking the advantages of strength reduction theory,a new method to calculate the safety factor of environments around deep pits has been discussed.This method takes the horizontal deformation of retaining structure reaching the control value in design as the critical failure of surrounding environment.By reducing soil material strength parameters step by step,the safety factor is obtained when reaching the critical condition.A project example shows that the method can be objective and effective to evaluate the safety margin of surroundings,and keep deep foundation pit construction safety smoothly.