Experimental Study On Distribution Law Of Abutment Pressure Under The Super Thick Conglomerate

The structure and movement of the strata with hard and thick roof,large burial depth and thick coal seam are the important influencing factors of mine dynamic load.The super thick conglomerate layers are widely distributed in the geology of the field in Shaanxi,Henan,Anhui and Shandong as special structures.Due to the special properties of the structure and mechanics of the super thick conglomerate layers,there are some differences in the law of abutment pressure between the coal seam excavation and the super thick conglomerates before and after the breakage.Among them,the dynamic change of abutment pressure around the working face is often the main source of power for the surrounding rock disaster,and it is very important to study the distribution law of the abutment pressure under the super thick conglomerate.Based on the geological conditions of the super thick conglomerate in the Qianqiu coal mine,this paper establishes a suitable abutment pressure mechanics model and simulates the influencing factors and distribution law of the abutment pressure under the super thickened conglomerate.At the same time,the optical fiber is shifted under external load,and the distribution law is analyzed,and the distributed fiber is used to lay the foundation for the test of the abutment pressur under the coalbed floor.Secondly,the three-dimensional test model is set up to study the distribution law of the abutment pressure of the coal and rock mass around the working face,and the distribute fiber sensing results of the test are compared with the traditional floor pressure sensors,and the results provide that the basis for improving the support state of excavation space and optimizing the advance support of roadway.The results show that according to the theory of key stratum and the key layer breaking load transfer characteristics before and after establishing the theory model,concluded that tend to abutment pressure peak value is 38 MPa,peak to the coal wall distance is about 95 m,affect the range of about 200 m,towards the abutment pressure peak value of 51 MPa,peak to the coal wall distance is about 100 m,influence range is about 210 m;Based on the FLAC3 Dnumerical simulation,the distribution of the pressure and the tendency of the pressure distribution and the characteristics of the distribution of the pressure distribution and the trend of the pressure distribution are obtained by using the FLAC3 D numerical simulation.The sensing optical fiber,the calibration experiment results show that the load and fiber brillouin frequency shift had good linear relationship,fitting coefficient is 0.952,and put forward the model test for the first time sensing fiber bearing pressure test system;Similar three-dimensional physical model experiment,the thick conglomerate layer broken first and periodic breakage have been accompanied by face strong pressure,which the thick conglomerate damage under the group first destroy the distance is 384 m,the group conglomerate cycle breaking distance of about 117.3 m,the first group conglomerate layer breaking distance is about 576 m,the group conglomerate layer cycle breaking distance is about 208 m,the group conglomerate layer fracture is the main power source stope surrounding power disaster;Distributed optical fiber abutment pressure test system can be used to characterize the change rule of abutment pressure in model test,have a good corresponding relationship with the traditional test,and optical fiber has high precision,strong anti-interference ability and so on electric sensor do not have advantage,provide new ideas for model experiment stope support pressure test.