深基坑多支点支护结构抗倾覆计算讨论

Discussion on anti-overturning calculation of multi-support retaining structure in deep foundation pit

不同地区的基坑规范对于计算基坑多支点支护结构抗倾覆性的规定有一定差异,这导致了采用不同基坑规范设计基坑需要的支护结构嵌固深度不相同。选取了《建筑基坑支护技术规程》(JGJ 120-2012)、上海市《基坑工程技术标准》(DG/TJ 08-61-2018)、广东省《建筑基坑工程技术规程》(DBJ\T 15-20-2016)三本基坑规范,分析了三本规范对于基坑抗倾覆稳定计算规定的不同之处,并结合具体案例,比较了这些不同之处对于支护结构嵌固深度的影响。结果表明,采用不同规范进行深基坑多支点支护结构设计时,支护结构的嵌固深度差异可达数米,这对基坑工程的经济性影响不可忽视;基坑所在的土层力学性质越差或基坑深度越大,支护结构嵌固深度差异越大。

There are some differences in the specifications of different areas for calculating the overturning resistance of multi-support structure in foundation pit,which results in different embedded depth of support structure required for foundation pit design by different foundation pit specifications.Technical specification for retaining and protection of building foundation excavations(JGJ 120—2012),Technical Code for Excavation Engineering in Shanghai(DG/TJ 08-61—2018),Technical Specification for Building Foundation Excavation in Guangdong Province(DBJ\T15-20—2016) were selected.The differences of the three specifications for anti-overturning stability calculation of foundation pit were analyzed and their effects on embedded depth of support structure were compared by combining specific cases.The results show that when different specifications are used to design multi-support retaining structure in deep foundation pit,the difference of embedded depth of support structure can reach several meters,which has an important economic impact on foundation pit engineering.The poorer the mechanical properties of the soil layer where the foundation pit is located or the deeper the foundation pit is,the greater the difference of embedded depth of support structure is.