基坑工程悬臂式支挡结构嵌固深度计算方法改进建议

国内基坑设计规范对悬臂式支挡结构嵌固深度的计算规定有较大争议,安全富余不足;欧洲标准和英国标准中的计算规定虽然理论正确,但采用传统简化方法计算得到的嵌固深度偏于保守。对悬臂式支挡结构嵌固深度的计算原理进行总结,并对国际和国内基坑设计规范中相关规定存在的问题进行分析。建议采用分项系数法并考虑严格的力和力矩平衡条件,进行悬臂式支挡结构的嵌固深度计算,得到的嵌固深度大于国内设计规范的计算结果,小于国际上通用简化方法的计算结果。采用改进的计算方法在理论上更合理,可以保障悬臂式支挡结构的安全和经济性。

Suggestion for improvement of calculation method for embedded depth of cantilever retaining structures in excavation engineering

The calculation provisions in Chinese design codes for excavation for determination of the embedded depth of cantilever retaining structure are disputed and the safety margin is not sufficient.The requirements in relevant Euro and British standards are theoretical correct but the traditional simplified method results in a conservative embedded depth.We summarize the basic rules for determination of the embedded depth of cantilever retaining structures,and analyze the problems of the relevant principles in Chinese and international design codes for excavation.We suggest that the partial factor method together with the strict load equilibrium and moment equilibrium conditions is used to calculate the embedded depth of cantilever retaining structure.The resulted embedded depth is larger than that calculated by Chinese standard,and is smaller than that calculated by the internationally accepted simplified method.The improved method is more rational in theory and can achieve a safe and economical design in practice.