近接房屋的隧道基坑失稳风险分析与管理

Instability Risk Analysis and Management for Tunnel Foundation Pit Close to Building

基于岩土力学与可靠度原理,在对类似工程地勘资料和监测数据统计分析的基础上,建立用于失稳风险失效概率分析的蒙特卡洛功能函数,推导出近接房屋的隧道基坑失稳风险计算模型。结合京石客运专线石家庄隧道工程,分析近接房屋的隧道基坑失稳风险,并提出风险控制措施。研究结果表明:近接距离小于4.4m时,风险可能发生;近接距离为4.4～9.2m时,风险偶然发生;近接距离大于9.2时,风险不可能发生。采取减小地质参数变异性、减小锚索力变异性和增大锚索力3种措施,可降低近接房屋的隧道基坑失稳风险;不同的近接距离应采用不同的风险控制措施。实际施工过程中房屋沉降量监测结果证明,提高锚索轴力10%和对地层注浆加固,可有效降低近接房屋的隧道基坑失稳风险。

Based on rock and soil mechanics,reliability principle and the statistical analysis of the geological prospecting and monitoring data of similar projects,Monte Carlo performance function used for assessing the failure probability of excavation instability risk was developed,and the numerical calculation model for the instability risk of tunnel foundation pit close to building was built.Combining with Shijiazhuang tunnel construction of Beijing—Shijiazhuang passenger dedicated line,the instability risk of tunnel foundation pit close to building was analyzed,and then risk control measures were proposed.The result shows that when the distance between the foundation pit and the building is less than 4.4 m,risk might happen.When the distance is 4.4~9.2 m,risk happens occasionally.When the distance is more than 9.2 m,risk is impossible to happen.Three measures,namely,reducing the variability of geological parameters,reducing the variability of the anchor cable force and increasing the anchor cable force,can reduce the instability risk of tunnel foundation pit close to building.Different risk control measure should be adopted for different distance.During practical construction,the settlement of building was monitored.Monitoring results show that increasing 10% of the anchor force and strengthening stratum by grouting can effectively reduce the instability risk of tunnel foundation pit close to building.