土岩二元结构地层地区吊脚墙基坑支护研究

Research on Design of Foundation Pit Support for Suspended Wall in Soil and Rock Dual Structure Stratum Area

以广州地铁21号线员村站基坑工程为例,针对土岩二元结构地层地区,基坑可分为上下两段进行计算,上段采用“吊脚地下连续墙+内撑(锚索)”的墙撑(锚)体系,下段采用岩质边坡锚喷体系,计算结果对比现场监测结果表明:(1)推荐算法适用于土岩二元结构地层吊脚墙的计算;(2)吊脚墙锁脚锚索对墙脚水平位移起明显控制作用,位移受锚索预应力大小的影响较大;(3)虽然吊脚墙的支护体系较常规支护体系水平位移大15%左右,但位移控制水平能够满足规范要求,并且该支护体系能够有效节省工期和投资。

With the deepening of the excavation depth of foundation pits, the geological conditions tend to become more complicated, and the forms of supporting structures tend to be diversified. Taking Guangzhou Metro Line 21 Yuancun Station as an example, for the soil-rock dual structure strata area, the foundation pit can be divided into two upper and lower sections for calculation.The upper section adopts the wall of "suspended base underground continuous wall + inner support(anchor cable)" supporting(anchor)system, and the lower section adopts the rock slope anchoring shotcrete system. The calculation results are compared with the on-site monitoring results. The results show that:(1)The recommended algorithm is suitable for the calculation of the suspended wall of the soil and rock dual structure;(2)The foot lock anchor cable of suspended wall has an obvious control effect on the horizontal displacement of the wall foot, which is greatly affected by the prestress of the anchor cable;(3)The supporting system of the suspended wall can effectively save construction period and investment, and the deformation of the foundation pit is about 15% compared with that of the conventional foundation pit.