柔性均布压力加载装置的研制及试验分析

DEVELOPMENT AND TEST ANALYSIS OF FLEXIBLE UNIFORM PRESSURE LOADING DEVICE

为真实模拟应力边界条件,保证结果的准确性,岩土材料及地质力学模型试验均需进行柔性边界加载。研制一种新型柔性均布压力加载装置,该装置由液压油缸、刚性推力器、超柔性调整橡胶和柔性传力橡胶等组成。采用数值方法分析和验证柔性加载的效果及传力性能,并结合配比试验,研制出适合岩土试验的特种柔性橡胶。将该加载装置与刚性加载的加载效果进行试验对比,结果表明,柔性均布压力加载相对于刚性加载效果显著,对于表面不平整的模型,柔性橡胶能更好地传递均布压力,并且模型内应力场均匀程度随着橡胶传力垫块的邵氏硬度的降低以及加载压力和距表面深度的增大而提高。带有超柔性调整橡胶和柔性传力橡胶组合垫层的加载装置具有很好的空间转动和变形传力性能,可更好地满足对具有不平整及倾斜表面模型进行柔性加载的要求。研究表明,柔性均布压力加载装置能真实地模拟应力边界条件,有利于提高岩土试验结果的准确性。

Flexible boundary loading is necessary for the real simulation of stress boundary condition, and is the premise to ensure the accuracy of geotechnical material test and geomechanical model test. A new flexible uniform pressure loading device is developed, which includes hydraulic cylinder, rigid thruster, hyper-flexible adjusted rubber and flexible transfer rubber etc. The force-transfer effect of flexible boundary loading is proved by numerical method; and the special flexible rubber which is suitable for test on rock and soil is developed by mix proportion test. The device is applied to the test, of which loading effect is compared with the one of rigid loading. The results show that the effect of flexible uniform pressure loading is more significant than that of rigid loading; and the flexible transfer rubber can transfer uniform pressure better on model with uneven surface. The even degree of model initial stress field increases with the Shore hardness of uniformity transmission rubber pads decreasing, loading stress increasing and depth from the surface increasing. The flexible loading device with hyper-flexible adjusted rubber and fexible transfer rubber has good character of space rotation and force transmission, and satisfies the demand of flexible loading on model with uneven surface or leaning surface. The study shows that the flexible uniform pressure loading device is able to implement the real simulation of stress boundary condition and improve the accuracy of test on rock and soil.