Study on evolution characteristics of stress field and support technology of roadway group

In order to study the evolution characteristics of the stress field of the roadway group excavation, taking the roadway group in Nanjiupan District of Du'erping Coal Mine as the research object, the vertical stress distribution characteristics of the roadway group under the step-by-step excavation method was studied by using the numerical simulation method. The results show that the stress concentration strength on the coal pillar side of the roadway is higher than that on the entity coal side. The peak stress location away from the lane for horizontal distance in coal pillar side is greater than the entity coal side. The coal pillar width influences stress concentration degree. When the width of coal pillar increases, the intensity of stress concentration decreases. The excavation of roadway group is in the area of high stress concentration, and the support design of roadway should consider sufficient abundance factor. In order to develop the technology of roadway adaptive support, the ground stress, strength and structure of surrounding rock were measured by field measurement method. The results show that the ground stress is at a medium level, forming a tectonic stress field dominated by horizontal stress. The orientation of roadway group's developing direction is favorable to the extension of in-situ stress direction, and the magnitude and direction of in-situ stress have little influence on the stability of roadway surrounding rock. Roadway roof is composed of sandy mudstone and thin coal line, which is a composite roof with variable thickness. The strength of coal and rock mass fluctuates greatly and is unstable due to the development of cracks. It is very important to control the caving of the composite coal and rock roof in the shallow part of roadway. Based on the distribution law of stress field of roadway group and the evaluation conclusion of geomechanics of surrounding rock, the prestressed rockbolt and anchor cable support technology is adopted in belt roadway, and the detailed scheme and supporting parameters are put forward, the field test has achieved good results, with the maximum displacement of 87 mm for the roof and floor and 81 mm for the two sides, which provides beneficial guidance for the excavation and support of the coal mine roadway group.