加筋土挡墙拐角处顶层格栅拉应力影响因素分析

Study of influence factors on tensile stress of top geogrid at the corner of reinforced earth retaining wall

以工程实例为背景,利用数值分析软件FLAC^(3D),在墙面内夹角为90°的单级直立式加筋土挡墙基础上,通过改变筋材间距、加筋长度、辅筋方式,建立加筋土挡墙三维数值分析模型。将3种影响因素下的不规则加筋土挡墙顶层土工格栅外缘、拐角平分线拉应力特征进行对比。结果表明:拐角部位土工格栅的最大拉应力分布呈现“X”形,与直线部位土工格栅拉应力平行墙面的分布规律有明显区别,且变形量较直线部位更大;土工格栅拉应力随着距拐角距离(0~15 m)的增大出现先增后减趋势,且在6 m处最大,15 m后变化较小,即实际工程中可在距拐角6 m左右提高挡土墙设计的稳定性;筋材间距、辅筋方式对土工格栅的变形都有明显的影响,加筋长度影响较小;当筋材间距等于0.3 m时,随着距墙面距离的增大,拐角部位与直线部位的土工格栅拉应力的差异减小,即拐角部位的变形程度减弱,挡墙的稳定性提高;小于筋材间距0.3 m时加筋效果不明显,故筋材间距0.3 m为最佳。筋材长度8~10 m时对减小拐角处土工格栅变形效果较好;整体增设辅筋时,墙高中下部拐角部位不再是土工格栅拉力最大处,拐角两侧沿墙面延伸大于拐角部位;相较于整体增设辅筋,一半辅筋对挡墙拐角处土工格栅变形的控制效果较弱,但可以起到很好的控制作用,也能节约材料,具体运用中根据实际情况拟定方案;实际中可选择改变筋材间距大小或增设辅筋的方式来控制土工格栅的变形,同时辅筋与主筋的间距大小对加筋效果的影响很小。

Taking engineering examples as the background,using the numerical analysis software FLAC^(3D),on the basis of the single-level vertical reinforced soil retaining wall with the angle of 90°in the wall,a three-dimensional numerical analysis model of reinforced soil re⁃taining wall was established by changing the spacing of reinforcement,the length of reinforcement,and the method of auxiliary reinforce⁃ment.The tensile stress characteristics of the outer edge and corner bisector of the top geogrid of the irregular reinforced soil retaining wall under three influencing factors were compared and studied.The results show that the maximum tensile stress distribution of the geogrid at the corner shows an“X”shape,which is significantly different from the distribution law of the tensile stress of the geogrid at the straight position parallel to the wall,and the deformation is larger than that at the straight position.The tensile stress increases first and then decreases with the increase of the distance from the corner(0-15 m),and the maximum is at 6 m,and the change is small after 15 m,that is,the stability of retaining wall design can be improved at about 6 m away from the corner in practical engineering;the spac⁃ing of the ribs and the way of the auxiliary ribs have obvious influence on the deformation of the geogrid,and the length of the reinforce⁃ment has little effect;When the spacing of the reinforcement is equal to 0.3 m,with the increase of the distance from the wall,the differ⁃ence of tensile stress between the corner and the straight part is reduced,that is,the deformation degree of the corner is weakened and the stability of the retaining wall is improved.When the distance is less than 0.3 m,the reinforcement effect is not obvious,so the reinforce⁃ment spacing of 0.3 m is optimal.When the length of the reinforcement is 8-10 m,the deformation effect of the geogrid at the corner is better.When the auxiliary reinforcement is added as a whole,the corner of the middle and lower part of the wall is no longer the place where the tensile force of the geogrid is the largest,and the extension of the two sides of the corner along the wall is greater than corner.compared with the overall addition of auxiliary reinforcement,the control effect of half of the auxiliary ribs have a weak control effect on the deformation of the geogrid at the corner of the retaining wall,but it can play a good control role and also save materials,and the spe⁃cific application depends on the actual situation;In practice,the deformation of the geogrid can be controlled by changing the spacing of the reinforcement or adding auxiliary reinforcement,and the distance between the auxiliary reinforcement and the main reinforcement has little effect on the reinforcement effect.