被动柔性防护网受力机理试验研究与数值计算

Test study of force mechanism and numerical calculation of safety netting system

针对落石被动柔性网防护结构系统,设计了新型大能量落石冲击试验台,进行了11组原尺寸被动柔性防护网落石冲击试验,研究了防护网系统的传力机理、破坏特征、计算单元理论和数值模拟技术。经试验结果分析,揭示了防护网系统3阶段传力的工作性态;指出了支撑索滑移、钢柱轴压-压弯屈曲失稳转换的传力机理,明确了导致防护网系统失效的关键因素;提出了被动柔性防护网系统索、网模拟的两阶段恢复力模型、减压环的三段非线性弹簧模型、钢柱底部的有限转动弹簧约束边界及落石冲击作用的等效荷载模型,初步搭建起被动柔性防护网系统的计算理论框架。对防护网进行了数值分析,与实测数据的对比表明了计算理论的正确性。

In order to study transfer mechanism and failure modes of the safety netting system （ SNS）, a new test table for high energy rock-fall was designed and built, then 11 full scale model tests were carried out. In addition, the theory of the computational elements and the numerical simulation technology were also explored. According to the test results, a three-stage mechanical behavior of SNS was revealed. Furthermore, a series of transfer mechanical process that sliding of the support rope eventually caused bulking of the steel column was presented for figuring out the significant failure factors of SNS. On this basis, a two-stage restoring force model of the rope and net and a three-stage nonlinear spring model of the energy dissipating device were proposed, as well as the rotation-limited constraint boundary condition at the bottom of the steel column and the equivalent load model of rock impact, so that the frame of computational theory of SNS was established preliminarily. Through the numerical simulation of SNS, the validity of the computational theory was testified by comparing with test results.