嵌入软岩的地下连续墙锚碇基础承载特性研究

Research on the Bearing Performance of Anchorage Foundation with Diaphragm Wall Embedded in Soft Rock

传统的重力式锚碇基础设计不考虑围护结构对基础承载力的贡献,而地下连续墙作为围护结构由于自身的结构特性,会在锚碇基础的承载时发挥一定作用。针对虎门二桥东锚碇基础,采用有限元方法分析了施加缆力前后锚碇基础的承载特性,并对地下连续墙在锚碇基础中荷载分担比和锚碇最大水平位移的影响因素进行了研究。结果表明,缆力的施加导致锚碇基础的水平剪力和弯矩均迅速增大并重新分布,地下连续墙始终承担了一定比例的荷载;施加缆力后,锚碇基础和地下连续墙的内力的峰值点或拐点均位于强风化软岩层与中风化软岩层分界面处,地下连续墙嵌入中风化软岩层的部分发挥了较大承载作用;地下连续墙的墙厚对地下连续墙在锚碇基础中的内力比影响最大;岩层弹性模量和地下连续墙的嵌岩深度对锚碇最大水平位移控制作用影响大。

Traditional design of gravity anchorage foundation does not consider the contribution of retaining structure to the bearing capacity of foundation,while diaphragm wall as retaining structure will play a certain role in the bearing capacity of anchorage foundation due to its own structural property.For east anchorage foundation for the Nizhou Navigation Channel of the Second Humen Bridge,finite element method is used to analyze its bearing performance before and after the cable force is exerted,and the relevant factors affecting the bearing capacity of diaphragm wall in anchorage foundation and the horizontal displacement of anchorage foundation are studied.Results show that:the exertion of cable force causes the shear force and bending moment of anchorage foundation to increase rapidly and redistribute,and the diaphragm wall always bears a certain proportion of load.After the cable force is exerted,the peak point or inflection point of internal force of anchorage foundation and diaphragm wall is located at the interface between the strongly weathered soft rock layer and the moderately weathered soft rock layer.The part of underground diaphragm wall embedded in the moderately weathered soft rock layer plays a greater role in bearing capacity.The thickness of diaphragm wall has the greatest influence on the internal force ratio of diaphragm wall in anchorage foundation.Elastic modulus of rock and rock-socketed depth of diaphragm wall have a great influence on the control of the maximal horizontal displacement of anchorage foundation.