摘要
悬臂挡墙是一种适用于地震地区的支挡结构,应用广泛,墙后填料一般具有一定的坡度角,其抗震设计仍面临如何确定地震土压力大小及其作用点、变形及破坏模式等诸多问题。另外,微型桩具有较好的抗震性能,其在浅层滑坡治理加固等领域得到了广泛的应用,针对其在横向动荷载作用下的受力特征、荷载与变形累积等方面的研究还相对较少。为此开展了悬臂挡墙支护的微型桩加固边坡地震响应特性的离心振动台模型试验研究,同时对典型工况进行了数值模拟。主要从3个方面对微型桩–悬臂挡墙支护边坡的地震响应特征进行了分析讨论:(1)边坡的地震加速度响应及其坡顶沉降变形;(2)微型桩地震响应与弯矩分布;(3)悬臂挡墙动土压力大小及作用点、弯矩大小及惯性弯矩的影响、地震位移变形模式、残余弯矩累积发展趋势。对输入输出加速度的传递函数分析表明,边坡土体对输入地震波中接近其自振频率的频率分量具有显著的放大效应;微型桩结构上部设置刚性连接梁能明显改善其受力性能,微型桩的柔韧性与延性等使其在地震荷载作用下可以耗散更多能量;悬臂挡墙上的惯性弯矩超过动弯矩的22%以上,不容忽视,当挡土墙后部填土坡度角较大且同时坡顶上部有荷载时,得到的动土压力系数ΔKae显著大于挡土墙后部填料为水平且无附加荷载的情况,试验数据表明多级地震后悬臂挡墙与微型桩的残余弯矩显著增加,这在其抗震设计中需引起重视。
As a retaining structure suitable for seismic areas,cantilever retaining walls(CRWs)are widely used,at the back of which backfills show a certain slope angle.Many problems(such as how to determine the level and point of action of the seismic earth pressure,displacement and deformation and failure mode)still occur during seismic design of retaining walls.Moreover,micropiles with favourable seismic behaviours have been extensively used in the fields of controlling shallow landslides and reinforcing slopes.Research on mechanical characteristics,load and deformation accumulation of micropiles under the lateral dynamic load remains sparse.To this end,the seismic response characteristics of a micropile-reinforced cut slope behind a CRW under multistage continuous earthquake loadings were studied by means of a centrifuge shaking-table model test.At the same time,the typical shaking event is numerically simulated.The seismic response characteristics of the slope system supported by micropiles and CRWs were analyzed and discussed from three aspects of seismic acceleration response of the slope and the settlement and deformation of the slope crest,seismic response of the micropiles and distribution of bending moment on the piles,and the level and point of action of the dynamic earth pressure,the bending moment and the influence of the bending moment of inertia generated by the selfweight of CRWs,displacement and deformation mode during an earthquake and cumulative development of the residual bending moment.A transfer-function analysis of the input and output accelerations shows that the slope soil has a significant acceleration amplification effect on the frequency components of the input seismic waves approaching their natural frequency.It is necessary to set the rigid connected beams on the upper part of the micropile structure,which is able to improve the mechanical performance of micropiles.Due to the flexibility and ductility of micropiles,more energy can be dissipated under the effect of seismic load.The bending moment of inertia on the CRWs cannot be ignored because it exceeds 22%of the dynamic bending moment.When there is a large slope angle of backfill,and loads are applied to the upper part of the slope crest,the dynamic earth pressure coefficientΔKae is much larger than that when the backfill is flat and no additional loads are applied.In addition,the significant residual bending moment is accumulated on CRWs and micropiles after earthquakes,which needs to be considered during the seismic design of retaining structures.
作者
孙志亮
孔令伟
王勇
周振华
SUN Zhiliang;KONG Lingwei;WANG Yong;ZHOU Zhenhua(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2022年第10期2109-2123,共15页
Chinese Journal of Rock Mechanics and Engineering
基金
国家重点研发计划项目(2018YFC1505304)
国家自然科学基金资助项目(41702348,51979269)。
关键词
边坡工程
离心振动台试验
动土压力
悬臂挡墙
微型桩
动土压力系数
残余弯矩
slope engineering
dynamic centrifuge test
dynamic earth pressure
cantilever retaining wall
micropile
dynamic earth pressure coefficient
residual bending moment
