考虑筋材蠕变-温度耦合效应的加筋土挡墙变形分析

Deformation analysis of geosynthetics-reinforced soil retaining wall considering coupling effects of reinforcement creep and temperature

基于既有土工合成材料筋材蠕变试验结果及蠕变特性分析,构建一种考虑蠕变-温度耦合效应的筋材本构模型,并利用二维瞬态热传导方程,建立计算加筋土挡墙温度的有限差分公式,进而确定加筋土挡墙温度并结合筋材本构模型计算面板水平位移和筋材最大应变,综合分析了初始温度、温度幅值、筋材层间距、墙顶超载、填土内摩擦角和导热率等因素对挡墙水平位移和筋材应变的影响。计算结果表明:挡墙竣工后初次环境温度升温过程使面板水平位移和筋材最大应变增加明显,后续温度周期性变化时挡墙变形增长缓慢;挡墙初始温度越高,其初期变形增加明显,而增加温度幅值导致面板长期变形量增加明显;增加墙顶超载、筋材层间距或减小填土摩擦角,导致相同时间内面板水平变形增加明显;填土导热率对面板水平位移和筋材最大应变的影响较小;环境温度周期性变化下,3 a内挡墙最大水平位移δ_(max)与墙高H比值δ_(max)/H变化范围在0.9%~1.5%;筋材最大应变靠近面板且最大值接近10%的限值,实践中应重点关注靠近面板的筋材长期性能变化对加筋土挡墙变形和稳定性影响。

By analyzing the existing creep test results and creep properties of geosynthetics,a constitutive model for reinforcement considering creep and temperature is estublished.Using the 2D-thermal transfer control equation,the finite difference formula is proposed to calculate the temperature in the geosynthetics-reinforced soil(GRS)retaining wall,and then the lateral deformations of the face of GRS wall and the_(max)imum reinforcement strains are determined via the calculated temperature and the constitutive model.Subsequently,a comprehensive study is carried out to investigate the effects of the initial temperature,temperature amplitude,vertical spacing of reinforcement,surcharge,in-frictional angle and thermal conductivity of backfills on the deformation and reinforcement strains.The results show that the elevated temperature after construction causes the significant increase of the lateral deformations of face and reinforcement strains,and then the variation of deformation decreases with the elapsed time.Increasing the initial temperature induces the remarkable increase in the lateral deformation at the very beginning,whereas the long-term deformation increases with the increase of the temperature amplitude.Increasing the surcharge on the top surface or vertical spacing,or reducing the in-frictional angle of backfills results in obvious increase of the lateral deformations.In addition,the thermal conductivity of backfills has small effects on the lateral deformations of face and the_(max)imum reinforcement strains.Under the action of cyclic ambient temperature,the ratio of the_(max)imum lateral deformation to the wall height,d_(max)/H,falls in the range of 0.9%to 1.5%,and the_(max)imum reinforcement strains,which occurr adjacent to the face of the retaining wall,reach almost 10%of the limited value.Thus,it is necessary to pay more attention to the effects of the long-term properties of reinforcement near the wall face on the deformation and stability of the GRS walls.