黏性填土重力式路堤墙曲线破裂面主动土压力分析

Analysis on active earth pressure of gravity embankment wall of cohesive backfill with curved failure surface

挡土墙承受的主动土压力一直是土力学重要课题,但至今未见填黏土路堤墙曲线破裂面并计及填土开裂的土压力分析法。为此,借鉴已有旋轮线破裂面和直线破裂面计及开裂的两极限平衡层分法开展研究,以弥补这一缺陷。先在滑体土中取一微分薄层,通过单元土体静力平衡分析,导出任意墙背和填土面倾角、填土性质及墙土接触条件下土压力求解公式;然后研究墙顶填土开裂过程及深度算法,采用计算机编程求极值,进而建立曲线破裂面计及填土开裂的路堤墙主动土压力分析方法;分别对比不计填土开裂的旋轮线破裂面法和考虑开裂的改进层分法对各算例土压力分析结果,验证了本研究方法合理且优越;最后通过变填土黏性路堤墙实例分析,进一步验证了本研究方法的唯一合理性及适用范围,并提出目前工程中此类挡墙设计尚存问题及建议。

The active earth pressure subjected to retaining wall has always been an important subject of soil mechanics,but there is still no analysis on earth pressure for embankment wall of cohesive backfill of curved rupture surface with soil cracking considered.In order to remedy this defect,two limit equilibrium methods of the existing cycloid failure surface and plane failure surface with soil cracking considered were used for reference to carry out research.Firstly,a differential layer in slipping soil was taken,and the earth pressure formula for arbitrary inclination angle of retaining wall back and backfill soil surface,filling property and contact conditions between wall and soil was derived by the element static equilibrium analysis.Then,the cracking process of wall-top backfill and its depth algorithm were studied,and the extreme value was solved by computer programming,and further the active earth pressure analysis method for cohesive backfill on embankment wall of curved failure surface with soil cracking considered was established;the results of earth pressure analysis method of cycloid failure surface without filling cracks and the modified method of layeranalysis with filling cracks were compared respectively in various examples,which proved that this method was reasonable and superior.Finally,the unique reasonability and application scope of this method are further verified via the example analysis of variable cohesive backfill on embankment toe retaining wall,which proposed the problems and suggestions for the design of such retaining wall.