地震动对锚索桩的响应特性研究

Dynamic Response Characteristics of Anchor Cable Piles under Ground Motion

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好,抗震性能高,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。鉴于此,利用FLAC3D对预应力锚索桩板墙的地震响应特征进行研究,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进行多种工况的分析,系统研究地震动参数对桩-土-锚动力耦合相互作用规律的影响。研究成果可加强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可靠的依据。

Prestressed anchor sheet pile wall is a light-weight retaining structure.As a new style of retaining structure,the stressed form of a prestressed anchor sheet pile is similar to a beam-style structure.This is deemed to be more reasonable than the stressed form of a cantilever that is usually used for stabilizing piles.In addition,because of advanced deformation compatibility and better seismic performance,the prestressed anchor sheet pile is widely used in landslide treatment.An investigation of seismic hazards in the Wenchuan earthquake suggests that a stabilizing pile has many advantages in terms of landslide treatment.Because this structure plays an important role in landslide treatment,many researchers have performed analysis on static design and loading characteristics;however,there is limited research on the seismic design theory of prestressed anchor sheet pile walls.The FLAC3 D model was used to study the seismic response of this structure,including the distribution of seismic earth pressure along the pile,deflection of the pile,and dynamic characteristics of cable stress in the anchor.In addition,the analyses of multiple cases were completed using various parameters of ground motion;thus,the influence of the parameters on the dynamic interaction law of pile-soil-anchor was systematically derived.Through FLAC3 D and a contrasting calculation,some conclusions are obtained.First,the anchor cable plays a limited role in the displacement of a pile wall structure,and an increase in soil pressure appears near the anchor cable.Because plastic deformation occurs in the soil on the surface of foundation before piling,paying attention to the embedded soil before piling is important as it has an active effect on the structural seismic performance.Second,the axial force is the largest in the free section of the anchor cable,and the value is an equivalent distribution.In the inner anchorage section,with an increase in anchorage depth,the axial force decreases.Shear stress increases sharply near the end of the inner anchorage section.The shear stress and anchorage depth curves are similar to a date pit,and with the increase of anchorage depth,the curve becomes gradually smoother.Moreover,the influence of ground motion characteristics on the seismic effect needs to be considered.Under ground motion,the seismic response order is consistent with the acceleration response spectrum near its natural period.The above research provides a basis for further details of prestressed anchor cable sheet pile walls in future.In addition,the results of this study strengthen the understanding of seismic performance and provide a reliable basis for further research.