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.
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))
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2012, Vol. 31 
