Experiment Study on Non-limit Passive Earth Pressure of Clay under Different Displacement Modes
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摘要: 为了揭示墙体平动和转动模式下黏土非极限被动土压力分布规律,采用自制模型箱,进行了墙体平动和转动模式下黏土非极限土压力试验,研究了墙体变位模式以及墙体位移大小对侧土压力的影响规律细化方法,首先进行了室内试验,得到了黏土的基本物理参数,其次进行了模型箱和测试仪器的固定安装,最后进行了挡土墙平移模式(T模式)、绕墙顶转动模式(RT模式)以及绕墙底转动模式(RB模式)3种模式下的土压力试验. 试验结果表明:T模式下,非极限侧土压力沿墙体深度的增加总体趋势增大,局部会有减小趋势,总体接近线性分布,当土体达到极限破坏时,靠近加载墙体处土体表面形成阶梯状错层;RT模式下,侧土压力随墙体的深度总体接近凹曲线分布,上部侧土压力随深度增加较慢,下部侧土压力随深度增加较快,当土体达到极限破坏时,靠近加载墙体处土体表面产生裂纹,模型箱中部土体表面鼓起;RB模式下,侧土压力随墙体的深度的增加先增大后减小,总体接近凸曲线分布,当土体达到极限破坏时,靠近加载墙体处土体表面形成阶梯状错层,其阶梯状错层范围要小于平动模式工况;三者非极限侧土压力合力随着压缩位移的增大而增大,当压缩位移相同时,RT模式下土压力合力与T模式下土压力合力比值在0.53~0.97之间,RB模式下土压力合力与T模式下土压力合力比值在0.65~0.83之间. 结论中是否有可以量化的数据,参考附件模板修改.Abstract: In order to reveal the depth distribution law of the non-limit passive earth pressure of clay on a rigid retaining wall under different displacement modes, translation and rotation experiments were carried out using the self-made model box. The influence of the three modes and corresponding displacement on the lateral earth pressure were studied. Firstly, laboratory experiments were carried out, and the basic physical parameters of clay were obtained. Secondly, the model box and test instruments were installed. Finally, earth pressure experiments under three modes of the retaining wall: translation (T-mode), rotation around the top of the retaining wall (RT-mode), and rotation around the bottom of the retaining wall (RB-mode) were carried out. The following conclusions are reached: In the T-mode, the lateral earth pressure generally increased with increasing soil depth except in some local parts, presenting an approximately linear distribution. When the soil reaches the limit state, step-like staggered floors are formed in the vicinity of the wall; In the RT-mode, the lateral earth pressure grow more slowly in the upper wall but more quickly in the lower wall as depth increased, presenting a concave curve. When the soil reaches the limit state, cracks are formed in the vicinity of the wall, and the soil summones up in the middle of the box; In the RB-mode, the lateral earth pressure grow more quickly in the upper wall but more slowly in the lower wall as depth increased, presenting a convex curve. When the soil reaches the limit state, step-like staggered floors are formed in the vicinity of the wall, with the scope smaller than that in the T-mode. The resultant forces of these three lateral earth pressures increase with increasing compressive displacement, reaching the maximum increasing magnitude in the T-mode. When the compression displacement is the same, the ratio of the earth pressure resultant force in the RT-mode and T-mode is between 0.53 and 0.97; the ratio of the earth pressure resultant force in the RB-mode and T-mode is between 0.65 and 0.83.
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表 1 土体物理参数
Table 1. Physical parameters of soil
参数 数值 φ/(°) 34 c/kPa 5 γ/(kN•m–3) 15.73 w/% 7.97 ${\rho _{{\rm{d}}\max }}$/(kg•m–3) 1 920 wp/% 22.7 表 2 非极限侧土压力合力比值
Table 2. Ratio of non-limit soil pressure resultant force
压缩位移/m PRT/PT PRB/PT 0.01 0.83 0.75 0.02 0.97 0.83 0.03 0.80 0.73 0.04 0.82 0.69 0.05 0.72 0.68 0.06 0.64 0.66 0.07 0.60 0.66 0.08 0.53 0.65 0.09 0.54 0.68 -
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