摘要
桩-土-斜撑组合支护体系是由双排桩、桩间土以及若干个钢管斜撑组成的新型基坑围护技术,虽在实际工程中积累了一定的实践经验,但理论研究尚不完善。对软土地区采用桩-土-斜撑组合支护体系基坑的开挖过程进行模拟,对基坑开挖过程中组合支护体系的变形规律、基坑的稳定性以及失稳滑移模式等进行了研究。研究结果表明:随着开挖深度的增加,基坑失稳破坏模式由滑移破坏模式转变为倾覆破坏模式,支护结构绕前排桩桩底旋转;钢管斜撑的存在使得组合支护体系有了较大的支护宽度,增强了基坑的稳定性,同时为双排桩的桩顶提供了一定的水平约束;随着钢管斜撑间距的减小,其在基坑支护体系中所起贡献逐渐增大,支护结构的整体性提高,土体剪切应变带的发展受到抑制,基坑稳定性系数逐渐增大,基坑失稳破坏模式由倾覆破坏向滑移破坏转变;对桩间土进行加固处理后,对基坑稳定性系数有一定程度的提高,但对基坑失稳破坏模式无影响,与调整斜撑间距配合,可以有效控制支护结构变形。
Pile-soil-inclined brace retaining structure is a novel retaining technique composed of double-row piles,soil between row piles and a number of steel-pipe inclined braces.Although some practical experience has been accumulated in engineering,the theoretical research is still not well developed.The dewatering and three-stage excavation of foundation pit with pile-soil-inclined brace retaining structure in soft soil area was simulated,and the deformation of retaining structure during the excavation process,excavation stability and collapse mechanism were studied.The results show that the collapse mode changes from slip collapse to overturning collapse with increasing excavation depth,the retaining structure rotates around the bottom of the front row pile after collapse;the existence of inclined brace makes pile-soil-inclined brace retaining structure have a larger width,which enhances the stability of foundation pit,and provides a certain level constraint for the pile top of double row piles;with the decrease of the distance between inclined braces,the contribution of inclined brace to retaining structure system increases gradually,the propagation of shear strain is inhibited,the stability coefficient of foundation pit increases gradually and the collapse mode changes from overturning collapse to slip collapse;the reinforcement of soil between row piles can improve the stability coefficient of foundation pit to a certain extent,but it has no effect on the collapse mode of foundation pit,in conjunction with adjusting the horizontal distance between inclined braces can obviously control the deformation of retaining structure.
作者
窦锦钟
孙旻
韩磊
Dou Jinzhong;Sun Min;Han Lei(China Construction Eighth Engineering Division Corp.,Ltd.,Shanghai 200122,P.R.China)
出处
《地下空间与工程学报》
CSCD
北大核心
2022年第S01期448-457,共10页
Chinese Journal of Underground Space and Engineering
基金
“十三五”国家重点研发计划(2017YFC0805004)
上海市科委“扬帆计划”(18YF1425000)
关键词
基坑
组合支护结构
降水分步开挖
稳定性
失稳破坏机理
foundation pit
combined retaining structure
dewatering and multi-stage excavation
stability
instability failure mechanism
