Study on the hydraulic action mechanism and support measures of weakly cemented muddy surrounding rock

There are a large number of argillaceous weakly cemented strata distributed in western China, and their significant hydraulic characteristics seriously restrict the safe and efficient exploitation of coal resources. In order to solve the problem of deformation and failure of the surrounding rock roadway in this type of strata, this study systematically studied the hydraulic disintegration behavior of argillaceous weakly cemented rocks by comprehensively using laboratory tests, theoretical analysis, numerical simulation and field experiments, established a constitutive model of argillaceous weakly cemented rocks considering hydraulic effects, revealed the deformation and failure mechanism of this type of surrounding rock roadway, and developed the combined support technology of high-strength anchor rod-anchor cable. The technology was applied and verified in the No. 5 mine of Dananhu Lake. The results are as follows: (1) The dried argillaceous weakly cemented rock specimens are more prone to disintegration than those without drying treatment; (2) A mathematical model that can describe the mechanical behavior of argillaceous weakly cemented rocks under hydraulic action is constructed, and the effectiveness of the theoretical model is verified by triaxial compression test. (3) The stress distribution and deformation law of the surrounding rock of the roadway under different moisture content conditions were analyzed: with the increase of moisture content, the stress concentration area of the surrounding rock gradually shifted to the depth, and the extreme value of the principal stress difference increased significantly, resulting in the risk of deformation and instability of the roadway intensified, and the proximity of the top and bottom plate in the middle of the roadway also continued to increase. (4) The joint support parameters are determined by numerical simulation optimization: the diameter of the roof plate and the two anchors is 2400 mm, the length is 2400 mm, and the spacing is 800 × 800 mm; The anchor cable has a diameter of 18.9 mm, a length of 6300 mm, and a spacing of 2400 × 2400 mm. (5) The field test shows that the subsidence of the roadway roof, the amount of two gangs moving closer, the amount of bottom drum and the degree of roof damage are reduced by 35%, 26.1%, 50% and 35.7%, respectively. This study provides a theoretical basis and technical support for the stability control of argillaceous weakly cemented rock roadway.