Study on deformation mechanism and control technology of roadway surrounding rock in ultra soft strata

In order to solve the low strength, poor bearing capacity, quick deformation and hard maintenance difficulty of the surrounding rock in the second mining block under the sea area of Beizao Mine, from the surrounding rock mechanics features, rheological features of the soft rock mine roadway, study was conducted on the disturbance influences, floor heave, dewatering and drying disintegration of the surrounding rock and other aspects. The deformation mechanism of the surrounding roc k in the type roadway was revealed. A support plan with high strength steel tube concrete supports was provided. The cross section of the mine roadway was circular. T he support steel tube of the steel tube concrete supports would be a中194 mmx8 mm steel tube and the joint coupling of the steel tube would be a中219 mmx8 mm ste el tube. The backfill would be conducted with C40 concrete. Behind the support wall, the auxiliary steel bar mesh support and shotcrete support would be made. The sit e test results showed that the deformation value of the support was 20 ~ 80 mm, the max deformation was 80 mm only, the support had not obvious deformation, the su pport plan with the steel tube concrete support could be able to control the surrounding rock deformation of the air return gateway in No. 2 mining block under the seam area of Beizao Mine and the surrounding rock of the gateway was kept in stable.