超大地下结构施工期水位随机分布抗浮可靠性分析与应用

Reliability Analysis and Application of Anti-floating of Random Water Level Distribution During Construction of Super-large Underground Structure

以发生抗浮失效的长沙某小区超大地下车库为例,基于ANSYS建立有限元模型,将构件尺寸、材料属性及水位变化作为随机输入变量,以抗浮桩拉断为失效指标,用高阶矩法与Monte Carol法分别计算施工期各个阶段及使用期的可靠度指标,并对输入变量进行敏感性分析,最后根据分析结果对设计及施工提出几点工程建议;研究结果表明:高阶矩法与Monte Carol法计算结果相对误差较小,可以作为简便算法应用;可靠性分析结果与实际相符,验证了可靠性分析的实用性,施工期可靠度低于限制,以可靠度指标来评价施工期抗浮具有重要意义;敏感性分析结果表明,水位变化是导致施工期及使用期可靠度变化的最主要原因,今后应重点关注于水位分布的影响。

The paper takes a large underground garage in a district of Changsha that failures to occur anti-floating as an example.Based on the ANSYS finite element model is established.The component dimensions material properties and the water level change are random input variables.The tensile failure of the anti-floating pile is an indicator.With the high order moment method and the method of Monte Carol at various stages during the construction and use are calculated separately.The reliability index and sensitivity analysis were carried out on the input variable.Finally according to the analysis results,some engineering suggestions for design and construction were put forward.The results showed that the calculation results of the high-order moment method and Monte Carol method have small relative errors and can be used as a simple algorithm.The reliability analysis results are consistent with the practice,which verifies the practicability of the reliability analysis.The reliability of construction period is lower than the limit.It is of great significance to evaluate the anti-floating of construction period with the reliability index.The results of sensitivity analysis showed that the variation of water level is the main cause of reliability variation during construction period and service period,and the influence of water level distribution should be paid more attention to in the future.