Centrifugal model tests on influences of foundation stiffness on stability of reinforced slopes
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摘要: 山区采用加筋边坡设计时经常依据现场情况选择基础形式，而基础刚度直接影响到加筋边坡的稳定性。通过开展离心模型试验，研究不同基础刚度条件下加筋边坡变形和筋材受力分布规律以及边坡稳定性。研究结果表明：边坡基础刚度越大，加筋边坡沉降和水平位移相对较小，且筋材拉力分布更为均匀，边坡稳定性更高；当基础刚度较小时，边坡底部区域的筋材拉力较大，容易导致加筋边坡整体产生较大变形甚至破坏；试验中采用高精度柔性应变片监测得到筋材拉力分布规律，基础刚度较小时，边坡下部的筋材拉力显著增大，比边坡中部的筋材拉力增幅更大，而基础刚度较大时，边坡中部和下部筋材拉力更为均匀。Abstract: The foundation form is often chosen according to the site condition when the reinforced slope is designed in mountainous areas. The foundation stiffness directly affects the stability of the reinforced slope. The centrifugal model tests were carried out to study the deformation and stress distribution of the reinforced slope as well as its stability under different foundation stiffness conditions. For the slope with larger foundation stiffness, the settlement and horizontal displacement of the reinforced slope are relatively small, and the distribution of reinforcement tension is more uniform, so the slope has higher stability. For the slope with small foundation stiffness, the reinforcement tension at the bottom area of the slope is larger, which is easy to cause the whole reinforced slope to produce large deformation or even damage. The high-precision flexible strain gauge is used to monitor the distribution of reinforcement tension. When the foundation stiffness is small, the tensile force of the reinforcement in the lower part of the slope increased significantly, which is larger than that in the middle part of the slope. When the foundation stiffness is large, the tension of the reinforcement in the middle and lower part of the slope are smaller and more uniform.
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表 1 离心模型试验方案
Table 1 Schemes of centrifugal model tests
试验编号 上部 下部 试验内容 T-1 填料二加筋 填料一 研究下部填料软弱下边坡稳定性及筋材应力分布 T-2 填料二加筋 填料二未加筋 研究下部回填料未加筋时边坡稳定性及筋材应力分布 T-3 填料二加筋 填料二加筋 研究下部回填料加筋边坡稳定性及筋材应力分布 
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表 2 模型填筑材料物理力学参数表
Table 2 Physical and mechanical parameters of model filling materials
填料 压实度 ρ干
/(g·cm-3)w/% c/kPa φ/(°) E/MPa 填料一 0.80 1.56 12.1 32.3 18 8.0 填料二 0.88 1.71 12.1 35.3 22 9.1
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表 3 模型筋材拉伸强度参数
Table 3 Expremental parameters of geogrid used in model
试验编号 每延米极限抗拉强度
/(kN·m-1)2%应变拉伸强度 5%应变拉伸强度 延伸率 1 5.35 0.79 1.70 108.9 2 5.12 0.68 1.59 90.4 3 5.16 0.66 1.58 94.1 4 5.36 0.80 1.73 100.1 5 5.00 0.63 1.50 84.8 平均值 5.25 0.69 1.60 96.92
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表 4 不同加速度下坡顶竖向位移
Table 4 Vertical displacements of slope top under different accelerations
(mm) 试验编号 20g 40g 60g 80g 试验T-1 0.85 11.30 22.62 — 试验T-2 0.35 1.18 3.23 7.77 试验T-3 0.30 1.13 2.80 6.60
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