红层软岩模型试验相似材料的配比试验研究

相似模型试验是研究红层软岩工程性质的重要手段之一，其试验结果的可靠性依赖于相似材料的正确选择与合理配比。针对红层软岩遇水极易软化的特性，在传统相似材料配比基础上添加生石灰，采用正交设计方法开展了相似材料配比试验，以骨料中铁粉与钡粉质量比例、铁粉与钡粉总质量中铁粉的质量比例、石膏质量、生石灰质量为4个因素，每个因素设置了5个取值水平，共制作25组、610个试样。每组试样均测试了其软化系数、密度、无侧限单轴抗压强度、抗拉强度及黏聚力与内摩擦角等物理力学参数，并研究了这些参数随上述4个因素取值水平的不同而变化的规律。最后，基于上述结果，配制了3种典型的软岩相似材料，并分别开展了真实软岩材料的饱水软化平行对比试验。研究结果表明：（1）根据配比方案所配相似材料物理力学参数可基本满足软岩相似模型试验的要求；（2）相似材料物理力学参数变化规律明显，便于通过调节其配比模拟不同软岩材料；（3）三组对比试验中相似材料饱水软化系数与真实软岩具有较高吻合度。

Experiment study on similarity ratio of similar material for model test on red-bed soft rock

The similarity model test is one of the important means to study the engineering properties of red-bed soft rock; the test result reliability depends on the correct selection and rational proportion of a series of similar materials. In view of the softening characteristics of the saturated soft rock, a series of mixture ratio tests on similar material with orthogonal design method is conducted by adding the quicklime into the traditional similar materials. Four influential factors are considered in all the tests, including the ratio of iron pore powder to barite powder to aggregates, the content and ratio of iron pore powder to iron pore powder plus barite powder, the content of gypsum, and the content of quicklime. Each factor is classified into 5 levels. In total, 610 specimens in 25 groups were prepared. For each group of specimens, the physico-mechanical indices, such as softening coefficient, density, unconfined uniaxial compressive strength, tensile strength, cohesive force, etc. were tested. On the basis of these test specimens, the influential factors of the concerned parameters were analyzed; meanwhile the applicability of the ratio result were examined. At last, the similar materials of three typical soft rock specimens were prepared to test the softening coefficient; and a comparison analysis was also carried out with the real soft rock test. The test results reveal that: 1) the physico-mechanical properties of the similar material fabricated according to the similarity ratio proposed in this paper may vary considerably, and this can meet the requirement of the geomechanical model test of soft rock; 2) the physico-mechanical properties of the similar material demonstrate an evident variation law that facilitates the identification of the optimum mixture ratio for any soft rock material; 3) the softening coefficients of the saturated similar material, in the three comparative tests, are consistent with the real soft rock to a great extent.