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在大比例尺的地质力学模型中,由于相似模型材料的脆性和低强度,很难测得其抗弯应力-应变或者荷载-位移全过程曲线。对抗弯试验的过程进行力学分析,通过对增加辅助弹性元件方案的假设推导得到弹性元件刚度设计原则。依据该设计原则,组装出一台试验原理样机,测到不同节理(均质、层状和块状)含不同角度锚杆的试件的抗弯荷载-位移全过程曲线。此外,由于相似材料的低强度重度大特性,试验中适当考虑试件的自重对实验结果的影响。试验研究表明,弹性元件的增加对抗弯荷载-位移全过程曲线下降段有着质的改善;当弹性元件与台架的复合刚度大于试件的最大刚度,即可测得抗弯荷载-位移全过程曲线;在抗弯试验中试件自重荷载可以等效为集中力荷载,对于550 mm的标准试件其等效荷载相当于其自身重力1/2的集中荷载,相当于试验中均质试件峰值荷载的9%。
In large-scale geomechanical models, it is difficult to measure the whole curve of bending stress-strain or load-displacement due to the brittleness and low strength of similar model materials. The mechanical analysis of the process of bending test is carried out. The design principle of the elastic stiffness of the elastic element is deduced from the assumption of increasing the auxiliary elastic element scheme. According to the design principle, a prototype of the test principle was assembled to measure the whole curve of bending load-displacement of specimens with different angles of anchor with different joints (homogeneous, layered and massive). In addition, due to the low-intensity, heavy-weight properties of similar materials, the effect of test weight on the test results is taken into account in the test. Experimental results show that the increase of elastic element has a qualitative improvement on the curve descending section of the whole process of bending load-displacement. When the composite stiffness of the elastic element and the gantry is greater than the maximum rigidity of the specimen, the bending load-displacement can be measured Process curve; in the bending test specimen self-weight load can be equivalent to concentrated load, the equivalent load for the 550 mm standard specimen equivalent to its own gravity 1/2 concentrated load, equivalent to the test homogeneous test 9% of peak load.