Research on the Ratio of Similar Materials of Weakly Expansive Surrounding Rocks in Northwest China based on Orthogonal Experiments
In order to obtain a more accurate proportioning scheme of similar materials for weak expansion mudstone,thereby reducing the material cost and time cost of model tests,and improving test efficiency and accuracy,based on the orthogonal theory,direct shear tests and free expansion rate tests were presenter in this paper to research the cohesion,internal friction angle and free expansion rate of similar materials in different proportions.Then sensitivity analysis was used to obtain the impact of changes in the material content of each ratio on the cohesion,internal friction angle and free expansion rate of similar materials.Then the regression equation was obtained through regression analysis.Finally,survey data of the Shanwan Tunnel,including free expansion rate,internal friction angle,and cohesion force,were substituted into the regression equation,and the material proportioning plan required for the model test was obtained which providing relevant basis for the model test of weakly expansionary surrounding rock in the northwest region.Experiments show that the materials,such as barite powder,lime,gypsum,red clay and bentonite,can well simulate the expansion properties of expansive rocks.Among them,the change in the ratio of barite powder to cement has the greatest impact on cohesion,while the change in the ratio of clay minerals to cement plays a major role in controlling the internal friction angle and free expansion rate.
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