沉井侧壁土压力极大值临界深度及其影响因素分析

Study on Critical Depth of the Maximum Sidewall Earth Pressure on Open Caisson and Its Influencing Factor

在分析现场实测资料的基础上,假定侧壁土压力极大值出现的临界深度,基于土拱效应原理,采用水平层分析方法,得到井壁处侧壁土压力系数及侧壁土压力计算式。根据沉井竖向平衡方程,反算出临界深度并分析了其影响因素。结果表明,随着沉井重量增加、土体内摩擦角增大,临界深度增大,即侧壁土压力极值点位置越偏下;随着井壁与土体外摩擦角增大、沉井高度增加,临界深度减小,即侧壁土压力极值点位置越偏上。该研究结果可有效指导沉井设计与施工。

Based on the field monitoring data and soil arching effect theory,the critical depth where produces the maximum value of sidewall earth pressure was assumed firstly.And then the sidewall earth pressure coefficient and the formula of sidewall earth pressure was calculated by using differential element method.On the basis of vertical balance equation of open caisson,the critical depth was back-calculated and the influencing factors were analyzed.The results show that the critical depth increases with the increase of the weight of the open caisson and soil internal frictional angle,which means the position where the maximum value of side wall earth pressure occurs moves down;on the other hand,the critical depth decreases with the increase of caisson-soil external frictional angle and the height of open caisson,which means that the position where the maximum value of side wall earth pressure occurs moves upward.The results can be used for the design and construction of open caisson.