基于挡墙平动的主动土压力计算方法研究

CALCULATION METHODOLOGY FOR ACTIVE EARTH PRESSURE UPON RETAINING WALL TRANSLATIONAL MOVEMENT

  • 摘要: 挡土墙的变形是影响土压力大小及分布的重要因素,该文在库仑土压力理论方法基础上,考虑破裂面上的变形、应力状态的不共步力学行为特征,采用双曲力学模型描述土体的力学特性,基于楔形体的静力平衡建立了引入挡墙变形的土压力计算方法。分析了砂土和黏性土土压力随挡墙变形的演化特征,砂土土压力随着挡墙变形的增加先急剧减小后缓慢趋于恒定值,挡墙变形Λ为(1‰~5‰)H时,砂土破裂面上大部分区域进入破坏后区的应力状态,土压力随变形的变化较小,取该变形值对应的土压力为主动土压力是合理的,黏性土土压力随着挡墙变形的增加先急剧减小后增大,最后达到恒定的土压力值,针对黏性土按照峰值应力强度库仑理论进行挡土墙的设计是偏危险的,应根据实际设计变形值或满足变形长度破坏率为95%的变形值对应的土压力值进行挡土墙的设计。将该文计算结果与库仑土压力进行对比得到一致的结果,只是对应的挡墙变形量不同。该方法可为挡墙变形的土压力计算提供参考。

     

    Abstract: Deformation of the retaining wall is one of the important factors influencing the dimension and distribution of earth pressure. In this study, on the basis of Coulomb's earth pressure theory, a hyperbolic mechanical model is used to describe the mechanical properties of soil. The mechanical behavior characteristics of the deformation and stress state of nonsynchronous behaviors on the fractured surface are considered. Then, the static equilibrium of the wedge of soil pressure calculation method has been set up upon the deformation of the retaining wall. The evolution characteristics of the soil pressure of sandy and cohesive soil with the deformation of retaining wall are analyzed. The earth pressure of sandy soil decreases sharply first and then slowly tends to a constant value with the increase of retaining wall deformation. When the deformation δ of retaining wall reaches (1‰~5‰)H, most areas on the broken surface of sandy soil enter the stress state of a post-failure zone, and the soil pressure changes little with the deformation. It is reasonable to take the earth pressure corresponding to the deformation value as the main earth pressure. The clay earth pressure decreases sharply first and then increases with the increase of retaining wall deformation, and finally reaches the constant earth pressure value. It is dangerous to design the retaining wall according to Coulomb’s theory for clay soil. The retaining wall should be designed according to the actual design deformation value or the corresponding earth pressure value satisfying the deformation length failure rate of 95%. The calculated results are compared with the Coulomb’s earth pressure, and the results are consistent. However, the corresponding deformation of retaining wall is different. This method can provide a reference for calculating earth pressure of retaining wall deformation.

     

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