白砂岩相似材料配比试验及特性分析

岩爆已成为隧道工程中的常见灾害,物理模型试验是模拟和解决岩爆问题的一种有效科学手段。制作物理模型,材料选取和配比是关键。选取成昆铁路峨米段月直山隧道白砂岩为模拟对象配制白砂岩相似材料,引入弹性能指数、脆性指数和剩余弹性能指数,采用正交设计法配比相似材料,结合影响因素敏感性分析法对试验结果进行分析研究。以石英砂、铁粉、石膏、水泥、缓凝剂和减水剂为主要材料,选取石英砂含量、铁粉含量、石膏水泥比和砂子粒径4个影响因素,每个因素设定4个设计水平,一共16组配比方案。测定每组试验方案材料的单轴抗压强度、抗拉强度、弹性模量、弹性能指数、脆性指数和剩余弹性能指数,对比分析这些指数随着4个影响因素的变化规律。最终挑选出合理的材料配比方案,得到满足要求的白砂岩相似材料。试验结果表明:基于弹性能指数、脆性指数和剩余弹性能指数,配制出的材料能够满足白砂岩相似材料模型试验的要求;以水泥作为胶结材料可以使相似材料峰后曲线变缓,有效增加材料储能能力;预配制出中等强度岩爆倾向性白砂岩相似材料的关键是要合理地控制好石英砂的含量和石膏水泥比两个因素,再根据实际情况调节铁粉含量和石英砂粒径大小。

Ratio Test and Characteristic Analysis of Similar Materials in White Sand Rock

Rock burst has become a common disaster in tunnel engineering. Physical model test is an effective scientific means to simulate and solve the problem of rock burst. Material selection and ratio are the key to make physical model. The white sandstone of Yuezhishan tunnel in Emi section of Chengzhou-Kunming Railway was selected as the simulation object to prepare the similar material of white sandstone, and the elastic energy index, brittleness index and residual elastic energy index were introduced. The orthogonal design method was used to mix the similar material and the sensitivity analysis method of influencing factors was used to analyze the test results. With quartz sand, iron powder, gypsum, cement, retarder and water reducer as the main materials, four influencing factors of quartz sand content, iron powder content, gypsum cement ratio and sand particle size were selected, and four design levels were set for each factor. There were a total of 16 matching ratio schemes. The uniaxial compressive strength, tensile strength, modulus of elasticity, elastic energy index, brittleness index and residual elastic energy index of the materials in each test scheme were measured, and the variation rules of these indexes with the four influencing factors were compared and analyzed. Finally, a reasonable material ratio scheme is selected to obtain similar white sandstone materials meeting the requirements. The test results show that: the material prepared based on elastic energy index, brittleness index and residual elastic energy index can meet the requirements of model test for similar materials of white sandstone; using cement as a cementing material can slow the post-peak curve of similar materials and effectively increase the energy storage capacity of materials; to produce similar materials of white sandstone with medium-strength rockburst tendency, it is necessary to reasonably control the content of quartz sand and the ratio of gypsum and cement, and then adjust the content of iron powder and the particle size of quartz sand according to the actual situation.