考虑偏压效应的边坡与基坑工程永临结合设计的研究

Research on the Permanent Temporary Combination Design of Slopeand Foundation Pit Engineering Considering Bias Pressure Effect

相较于单一的边坡或者基坑工程,永-临结合工程目前缺乏成熟的支护理论和方法。永久支护(设计使用寿命超过2年)和临时支护(设计使用寿命不超过2年)结合的工程常分开设计,而忽略相互间的作用和影响。近年来,城市地下空间呈现迅猛发展的态势,出现了越来越多的基坑紧邻既有山体边坡的工程。此工程的基坑开挖改变了边坡原有的应力分布状态,对边坡的稳定产生不利影响;同时,边坡对基坑的偏压荷载使得基坑支护体系受力变得更加复杂。针对这一问题,武汉市某永-临结合工程在充分考虑了边坡-基坑结合支护下应力和位移相互影响,利用有限元分析方法分析了施工过程位移与沉降变化规律,并通过监测反馈进行验证。结果表明考虑了偏压效应的联合支护方案与监测结果较为吻合,在边坡偏压影响的区域,边坡与基坑需要共用围护体时应提升基坑临时性支护为永久性支护。

Compared to a single slope or foundation pit project,the combination of slope and foundation pit engineering currently lacks mature support theories and methods.The combination of permanent support(designed to have a service life of more than 2 years)and temporary support(designed to have a service life of no more than 2 years)is often designed separately,ignoring their mutual effects and impacts.In recent years,urban underground space has shown a rapid development trend,with more and more excavation projects adjacent to mountain slopes appearing.The excavation of the foundation pit in this project has changed the original stress distribution state of the slope,which has adverse effects on the stability of the slope;At the same time,the bias pressure load of the slope on the foundation pit makes the stress of the foundation pit support system more complex.In response to this issue,a slope and foundation pit combination project in Wuhan City fully considered the mutual influence of stress and displacement under the slope foundation pit combination support.The finite element analysis method was used to analyze the displacement and settlement changes during the construction process,and verified through monitoring feedback.The results show that the combined support scheme considering the bias effect is in good agreement with the monitoring results.In the area affected by slope bias,temporary support should be designed as permanent support when the slope and foundation pit need to share the same enclosure.