Abstract：The shear force in retaining structure of foundation pits will be too large while the lowest support is set too high，which may lead to punching shear failure of the retaining structure. Such failure is a kind of brittle fracture and it usually occurs suddenly，which may result in disastrous consequences. The safety factor commonly used can only control the embedment depth of retaining structures，but they can not control the height of the lowest support. So，such failure can not be avoided. Therefore，the safety factor of the punching shear-resistant stability is proposed. The failure modes and features of punching shear failure of the retaining structure have been described. And then，the calculation method of the safety factor of the punching shear-resistant stability is put forward. The study results show that even all other safety factors are satisfied，it is still necessary to check the safety factor of the punching shear-resistant stability and to analyze the rationality of the lowest support height. The safety factor of the punching shear-resistant stability is applied to explain the failure mechanism of collapse accident of a domestic metro foundation pit. Calculation analysis also shows that using the safety factor to control the height of the lowest support can achieve a linear relationship between various safety factors and embedment ratio. The safety factor is simple in form and easy to calculate；so it has important applications to design and construction of the foundation pits.
王洪新，周 松. 基坑围护结构的抗冲剪稳定安全系数的计算与应用[J]. 岩石力学与工程学报, 2012, 31(11): 2312-2318.
WANG Hongxin，ZHOU Song. CALCULATION OF SAFETY FACTOR OF PUNCHING SHEAR-RESISTANT STABILITY FOR RETAINING STRUCTURE OF FOUNDATION PITS AND ITS APPLICATION. , 2012, 31(11): 2312-2318.
[1] 刘建航，侯学渊. 基坑工程手册[M]. 北京：中国建筑出版社，1997：127–130.(LIU Jianhang，HOU Xueyuan. Excavation engineering handbook[M]. Beijing：China Architecture and Building Press，1997：127–130.(in Chinese))
[2] 王洪新，陈建军，刘翼山. 基坑抗隆起稳定安全系数实用计算分析与应用[J]. 岩石力学与工程学报，2007，26(增1)：3 223– 3 230.(WANG Hongxin，CHEN Jianjun，LIU Jishan. Practical calculation analysis and application of safety coefficient of heave-resistant stability of foundation pit[J]. Chinese Journal of Rock Mechanics and Engineering，2007，26(Supp.1)：3 223–3 230.(in Chinese))
[3] 王洪新. 基坑宽度对围护结构稳定性的影响[J]. 土木工程学报，2011，44(6)：120–126(WANG Hongxin. Influence of excavation width on enclosure-structure stability of foundation pits[J]. China Civil Engineering Journal，2011，44(6)：120–126 (in Chinese))
[4] 中华人民共和国国家标准编写组. GB 50010—2010 混凝土结构设计规范[S]. 北京：中国建筑工业出版社：2010.(The National Standards Compilation Group of People?s Republic of China. GB 50010—2010 Specification for design of concrete structures[S]. Beijing：China Architecture and Building Press，2010.(in Chinese))
[5] 张旷成，李继民. 杭州地铁湘湖站“08.11.15”基坑坍塌事故分析[J]. 岩土工程学报，2010，32(增1)：338–342.(ZHANG Kuangcheng，LI Jimin. Accident analysis for “08.11.15” foundation pit collapse of Xianghu Station of Hangzhou metro[J]. Chinese Journal of Geotechnical Engineering，2010，32(Supp.1)：338–342.(in Chinese))
[6] 李宏伟，王国欣. 某地铁站深基坑坍塌事故原因分析与建议[J]. 施工技术，2010，39(3)：56–62.(LI Hongwei，WANG Guoxin. Causes and suggestion on deep foundation excavation accident in some metro station[J]. Construction Technology，2010，39(3)：56–62.(in Chinese))
[7] 王洪新. 水土压力分算与合算的统一算法[J]. 岩石力学与工程学报，2011，30(5)：1 057–1 064.(WANG Hongxin. Unified method of separate and combined calculation of water and earth pressures[J]. Chinese Journal of Rock Mechanics and Engineering，2011，30(5)： 1 057–1 064.(in Chinese)
2012, Vol. 31 
