刚度可调层状多向剪切模型箱的研制及性能测试

Development and performance test of a stiffness-variable multidirectional laminar shear model container

为满足不同场地条件下岩土工程振动台试验的需求,在总结国内外振动台试验土箱经验的基础上,研制了刚度可调的层状多向剪切模型箱。该剪切箱由系列空心环形钢框架堆叠而成,层间由滚珠和螺杆相连,高度可根据试验工况改变,通过调节螺杆的刚度、数量和排列方式等,实现其刚度变化。利用ABAQUS软件分析得出各种组合模型箱的特征频率,验证了箱体刚度可调的特性。运用该模型箱开展了自由场振动台试验,分析了不同高度、距箱侧壁不同距离处观测点的加速度时程及其相应反应谱,并采用2-范数偏差指数对边界效应进行量化。结果表明,新研制的层状剪切箱无明显的边界效应,能较好地实现自由场地在平面内的动力响应。

Based on the development experience of soil containers for shaking table tests, a multidirectional laminar shear model container with variable stiffness is designed to meet the needs of shaking table tests in geotechnical engineering under different site conditions. The container is constructed with a stack of annular steel frames, and supported by ball bearings and bolts. Its height can be adjusted according to the test conditions. By adjusting the stiffness, the number, and the arrangement of bolts, the stiffness of the container can be changed. The stiffness-variable characteristic of the container is verified by analyzing the characteristic frequencies of various combined model boxes in ABAQUS. Then a free-field shaking table test employing the container is performed. The test results are discussed in terms of the acceleration time histories and the corresponding response spectra at various heights and distances. A 2-norm deviation index is also used to quantify the boundary effects. The result shows that the developed laminar shear container does not impose significant boundary effect and is able to maintain the in-plane free-field response.