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Numerical simulation of dynamic shear characteristics of geomembrane interface and its application
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摘要: 利用改装的土石料大型剪切仪对土工膜-砂砾石界面开展循环剪切试验，获得土工膜界面在不同竖向压力下的滞回曲线、主干线和阻尼比曲线，建立相应的剪切劲度和等效阻尼比数学模型。在此基础上对循环剪切试验开展有限元数值模拟，所得计算结果与试验值总体吻合较好，合理反映了土工膜界面循环剪切过程的非线性和滞后性，验证了所建土工膜界面本构模型的正确性。进一步将模型应用于土工膜防渗土石坝的抗震分析中，计算得到的坝面土工膜的动位移、加速度、动主拉应变和动主拉应力符合一般规律，表明所建本构模型用于土工膜防渗土石坝抗震分析是正确可行的。Abstract: A series of cyclic shear tests were carried out on geomembrane-gravel interface using a modified large-scale shear device for soils. The hysteretic curves, backbone curves and damping ratio variation curves under different vertical pressures were obtained, and the corresponding mathematical models for shear stiffness and equivalent damping ratio were established. Further, the finite element numerical simulation of cyclic shear test was performed, and the results are in good agreement with the test data, which reasonably reflects the nonlinearity and hysteresis of cyclic shear. Finally, the proposed interface model was applied to the dynamic analysis of a geomembrane faced earth-rock dam. The calculated dynamic displacement, acceleration, dynamic principal tensile strain and dynamic principal tensile stress of geomembrane on the dam surface conform to the general rules, which indicates that the established interface model is correct and feasible for seismic analysis of geomembrane faced earth-rock dams.
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图 1 土工膜-砂砾料界面阻尼比与剪切位移关系
Figure 1. Relationship between damping ratio and shear displacement of geomembrane-gravel interface
图 2 土工膜-砂砾石界面的剪应力和剪切位移关系
Figure 2. Relationship between shear stress and shear displacement of geomembrane-gravel interface
图 3 蓄水期土工膜位移分布（单位：cm）
Figure 3. Displacement distribution of geomembrane during water storage period (unit: cm)
图 4 蓄水期土工膜静力主拉应变和主拉应力
Figure 4. Static principal tensile strain and stress of geomembrane during water storage period
图 5 地震作用下坝面土工膜动位移包络图（单位：cm）
Figure 5. Dynamic displacement of geomembrane under earthquake (unit: cm)
图 6 地震作用下坝面土工膜动主拉应力和动主拉应变包络图
Figure 6. Dynamic principal tensile stress and strain of geomembrane under earthquake
图 7 静动力叠加后土工膜主拉应力包络图（单位：MPa）
Figure 7. Principal tensile stress of geomembrane after static and dynamic superposition (unit: MPa)
表 1 坝料静动力计算参数
Table 1. Static and dynamic parameters of dam materials
材料 $\gamma $/(kN·m−3) $\varphi $/° $\Delta \varphi $/° $K$ $n$ ${R_{\rm{f}}}$ ${K_{\rm{b}}}$ $m$ ${K_{{\rm{ur}}}}$ ${K_{\rm{d}}}$ ${n_{\rm{d}}}$ ${\lambda _{\max }}$ 保护层 22.0 41.0 5.5 1 080 0.41 0.85 470 0.30 2 100 1 420 0.60 0.20 垫层 23.0 46.5 5.2 1 150 0.45 0.92 510 0.32 2 200 1 680 0.65 0.22 过渡层 22.5 45.8 6.2 1 050 0.40 0.88 460 0.24 2 000 1 550 0.63 0.25 主堆 21.6 45.0 9.5 950 0.37 0.84 430 0.18 1 950 1 332 0.55 0.26 次堆1 21.0 42.5 8.0 900 0.29 0.80 370 0.10 1 700 1 165 0.45 0.28 次堆2 21.0 40.5 8.5 850 0.32 0.82 360 0.15 1 550 1 018 0.42 0.28 
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