预应力锚索桩板墙的地震响应及影响参数研究

汶川地震震害调查表明,使用预应力锚索的桩板墙变形协调性更好,抗震性能提高,但目前在预应力锚索桩板墙的抗震设计理论研究方面仍比较落后。本文利用FLAC^3D对预应力锚索桩板墙的地震响应特征进行了研究,包括桩身土压力分布、桩身变位及锚索内锚段应力的动力响应特性等,并通过改变地震动参数、材料参数和结构设计参数,进行了多种工况的分析,系统研究了影响参数对桩-土-锚动力耦合相互作用规律的影响。通过对FLAC^3D的数据分析,其研究结果表明:锚索限制了桩板墙结构的运动,墙后土压力在锚索附近显著增大;桩前基础表面的土体易损坏,因此,应高度重视桩前位置,这对抗震设计有积极影响;随着内聚力和内摩擦角的增大,桩的位移、应力和锚固轴力等减小;锚索存在临界有效锚固长度,在临界范围内,通过减小桩间距来提高加固效果并不明显。研究成果加强了对预应力锚索桩板墙抗震表现的认识,也为深化抗震机理研究提供了可靠的依据。

Research on Seismic Responses and Influence Parameters for Prestressed Anchor Sheet Pile Wall

The prestressed anchor sheet pile wall is a new type of light retaining structure, and has been widely used. Researches show that the sheet pile wall with prestressed anchor has been proved to have better performance due to advanced deformation compatibility. Whereas, the research on seismic design theory of prestressed anchor sheet pile wall is laggard at present. Therefore, FLAC^3D was performed to study seismic responses of this structure, including distribution of seismic earth pressure along pile, deflection of pile, dynamic characteristics of cable stress in anchorage segment, etc. In addition, analysis of multiple cases were completed through changing parameters of ground motion, material, and structure, so the influence of parameters on dynamic interaction law of pile-soil-anchor was systematically discussed. Through data analysis from FLAC^3D, some conclusions are obtained. Firstly, anchor cable limits the movement of sheet pile structure, and the increases the earth pressure near the anchor position. The soil on the surface of foundation before pile is easy to damage. Therefore, the position of fore shaft should receive a great of attention, which has a positive effect on seismic performance. Secondly, with the growth of cohesive force and angle of internal friction, the values of displacement, stress of pile, anchor axial force get smaller. Thirdly, within the critical pile spacing, it is not obvious to improve the reinforcement effect through reducing the pile spacing. The results of analysis strengthen the understanding of this structure for seismic performance, and provide a reliable basis for further research of seismic mechanism.