受静载和循环荷载作用的基础下加筋挡墙工作性能分析

Performance of geogrid-reinforced soil retaining walls subjected to static and cyclic footing loadings

基于受静载和循环荷载作用的基础下加筋挡墙模型试验,综合对比分析了基础位置、荷载大小、频率和循环次数等因素对加筋挡墙力学与变形性能的影响。试验结果表明:(1)以基础极限承载力为标准,确定基础最佳偏移距离为0.3H(墙高);(2)基础沉降和挡墙水平位移随荷载、频率和循环次数的增加而增加,当基础受静载且达到极限承载力前,沉降与墙高比均小于2%,挡墙水平位移与墙高比均小于1%;当基础受循环荷载时,增加循环荷载水平和频率使初始阶段基础沉降和挡墙水平位移增加明显,但随循环次数增加而变形收敛;(3)紧邻基础下方的筋材应变显著高于其他层,且循环荷载水平越高,循环次数增多时筋材应变增幅显著;(4)静载时挡墙破坏随基础偏移距离增加而由初始顶层面板被挤出,逐渐过渡到破坏面沿基础边缘并向挡墙深部发展的剪切破坏为主;当基础受循环荷载且频率较小时,顶层面板以挤出变形为主,增加荷载水平和频率,挡墙以中部面板挤出破坏为主。

The model tests of geogrid-reinforced soil retaining walls（GRSRW） subjected to the static and cyclic footing loadings were carried out to investigate the mechanism and deformation characteristics of GRSRW considering the factors such as the location of footing,the magnitude of the load,the frequency of load and the numbers of loading cycles. The optimum of offset,0.3H（H,height of wall）,was determined based on the analysis of ultimate bearing capacity of the footing on the top of the retaining wall. The settlement of the footing and the lateral deformation of geogrid-reinforced soil walls increase with the increase of the magnitude of loading,the frequency and the number of loading cycles. When the static load applied on the footing is less than the ultimate bearing capacity,the ratio of the settlement to the wall height is less than 2% and the ratio of the horizontal deformation to the wall height is always less than 1%. When the cyclic loading is applied on the top surface of retaining walls,the settlement and the horizontal deformation increase remarkably compared with those under the same level of static loads. With the increase of cyclic loads and frequency,the settlement and the horizontal deformation increase quickly at the very beginning and then the increasing slows down as the number of cycles increase. The strains in geogrids for the uppermost layer which are generally greater than those in the other layers,increase significantly when the higher cyclic loads with larger cyclic numbers are applied. The failure mode of the retaining walls under the static loading and lower cyclic loads with low frequency is that the top panel blocks is squeezed out. The failure surface occurs at the verge of foundation and then develops deeper when the offset of the footing increases continually. The blocks in the middle of retaining wall tend to be squeezed out when the cyclic loads and the loading frequency increase.