Study On The Mechanism Of Top-cutting And Pressure-relief Bolt-grouting Support In The West Wing Of Pingdingshan No.8 Mine

Under the influence of long-term mining in the 14200 working face,along with the fracture and rotation of the direct roof and the old roof,the soft rock roadway is the transmission mechanism of the passing force of the coal roof.The surrounding rock will be damaged under long-term compression and shearing.It shows the characteristics of large roadway deformation such as violent bottom heave and large moving amount of the two sides.The most serious roadway section has moved closer to about 2.0m.The bearing performance of broken surrounding rock and supporting structure is the key to the stability of soft rock roadway.This paper uses a variety of methods such as theoretical analysis,laboratory test research,numerical simulation calculation,and on-site industrial test to study and analyze the failure mechanism of the original support structure and the failure characteristics of the soft rock broken roadway,combined with the blasting of the roadway roof before the implementation of the support work Top-cutting,pressure relief,and other work,focusing on the study of the grouting and cementing bearing performance,deformation,and re-failure characteristics of broken rock masses.Based on the analysis of the grouting cemented sample bearing performance,numerical simulation methods are used to simulate and study grouting,etc.Effective reinforcement layer is effective for roadway stability problems.The key technology of grouting equivalent reinforcement layer for soft rock and broken roadway surrounding rock reconstruction is proposed and used in industrial tests.The main research results of this paper are divided into the following four aspects:(1)By analyzing the spatial position relationship and engineering geological conditions of the roadway in the west wing of the return wind downhill,the key influencing factors of the roadway floor heave and the outburst of the two sides of the displacement are analyzed.At the same time,based on the theory of surrounding rock damage,key technologies for the stability control of broken surrounding rock,and industrial tests,a roadway bolt and grouting secondary support plan is proposed for soft rock roadways that are severely affected by dynamic pressure.(2)Using laboratory tests,the grouting and cementation test of rock samples after the peak is carried out.The uniaxial compressive strength of the grouting and cementation of the broken surrounding rock samples after the peak is greatly improved compared with the residual strength after the peak,and the comparison is complete.The compressive strength of the sample has also recovered.Through the experimental analysis of Portland cement and ultrafine cement grouting cement samples with different water-cement ratios,and the analysis of the properties of the grouting fluid,the comprehensive grouting strength,economic benefits,and economic benefits of the Portland cement grouting fluid with a water-cement ratio of 0.8 are obtained.For factors such as fluidity,it is most ideal as a grouting fluid for surrounding rocks.By analyzing the damage and reconstruction mechanism of the sample,the basic physical and mechanical parameters of the disturbed roadway surrounding rock and the physical and mechanical parameters of the grouting cemented sample are obtained,which lays the foundation for the numerical simulation of the stability of the roadway.(3)By analyzing the penetration range of the grouting liquid,the thickness range of the grouting cemented surrounding rock is obtained.It is assumed that the grouting cemented surrounding rock layer and the prestressed anchor rod(cable)work together to form an equivalent reinforcement layer of anchoring and grouting.Numerical simulation software is used to study the stability of the roadway under the environment of grouting and anchoring equivalent reinforcement layers of different thicknesses.The results show that the thicker the anchor-grouting equivalent reinforcement layer,the smaller the roadway deformation problem and the better the supporting effect.The maximum deformation of the monitored roadway is less than 100 mm,and the design of the roadway support for the return wind downhill in the west wing meets the needs of production.(4)Based on test data,numerical simulation,support analysis,and engineering geological condition analysis,the support plan of the west wing return wind downhill roadway was optimized.The grouting liquid material and its water-cement ratio,support parameters and process flow are obtained.The roadway convergence and deformation monitoring is carried out in real time after the support construction is completed.The results show that the bolt and grouting support has a significant effect on soft rock dynamic pressure roadway support.,Its displacement and deformation rate is significantly reduced,and within the controllable range,monitoring the final deformation is less than 100 mm,which is of great significance to the deformation control of soft rock dynamic pressure roadway.