本文以陇南市东江初级中学综合教学实验楼基坑支护工程为背景,运用PLAXIS对该基坑进行了开挖全过程的数值模拟分析,结合现场实测结果分析了深基坑旋喷桩的加固效果,并与未采用旋喷桩加固的情况进行了对比分析。结果表明:对于长江支流的白龙江II级阶地力学性质差的饱和土地区,采用旋喷桩加固桩间土及坑内土体能够很好地提高桩周土体强度、限制桩顶位移、减小坑外沉降,可使支护桩桩顶水平及竖向位移减小50%,桩身内力减小10%;增加旋喷桩加固长度对限制支护结构变形效果不大,但增加宽度效果明显,可使支护桩桩顶水平位移减小50%以上,但同时存在最优加固宽度;采用旋喷桩的深基坑加固措施安全可靠、经济合理,对该类地区的类似深基坑工程具有参考及借鉴作用。

This paper takes the foundation pit support project of comprehensive teaching experimental building of Dongjiang Junior Middle School in Longnan City as the background. The whole excavation process of the foundation pit was simulated by PLAXIS and combined with the field measurement results, the reinforcement effect of rotary jet grouting pile in deep foundation pit is analyzed and compared with that without rotary jet grouting pile. The results show that for the saturated soil areas with poor mechanical properties of grade II terrace in the Bailong River tributary of the Yangtze River, using jet grouting pile to reinforce soil between piles and soil in pits can improve the strength of soil around piles, limit the displacement of pile top and reduce the settlement outside pits. It can reduce the horizontal and vertical displacement of the top of the supporting pile by 50%, and the internal force of the pile body by 10%; It is proved that increasing the reinforcement length of the jet grouting pile has little effect on limiting the deformation of supporting structure but the effect of increasing the width is obvious, which can reduce the horizontal displacement of the support pile top by more than 50%. There is also an optimal reinforcement width. Reinforcement measures of deep foundation pit by jet grouting pile are safe reliable and economically rational, which can be used for reference for similar deep foundation pit projects in this kind of area.