Coal and gas outburst multi-functional physical model testing system of deep coal petrography engineering

Multi-functional physical model testing system of deep coal petrography engineering can be used to carry out the physical modeling experiments on the coal and rock mass engineering problems such as coal and gas outburst,hydraulic coal seam anti-reflection,underground engineering deformation and destruction,and supercritical carbon dioxide fracturing. From the perspective of coal and gas outburst,based on the influencing factors such as ground stress,gas pressure,coal body properties,geological structure and mining disturbance,the functions and characteristics of the system in coal and gas outburst experiments were analyzed and compared. The system consists of six parts:main device,model forming and positioning system,hydraulic servo loading control system,gas pumping or injection system,simulation excavation system and data acquisition system. It has the following characteristics:①Main device adopts the steel cylinder structure of "round exterior and square interior",which effectively increases the rigidity and bearing capacity of the bearing system,and the load is not transmitted,avoiding the occurrence of local stress concentration; ②Main device can accommodate a large size model (2 060 mm×1 200 mm×1 200 mm),simulating geological structures,high degree of similarity and small boundary effect; ③The gas storage space of the model chamber is large,and the continuous supply capacity of gas source is strong. The process of far-field gas migrating to the outburst area under real conditions is restored; ④20 hydraulic puller seals are arranged in the circumferential direction to ensure uniform force on the pull rod of the main device,and the maximum sealing pressure of the device is up to 5 MPa; ⑤Loaded with 432 small cylinders,it achieves a three-way independent uniform or non-uniform loading,the maximum loading stress is 10 MPa,and the air pressure and solid pressure do not interfere with each other during loading. ⑥The automatically controlled simulated excavation system restores the disturbance behavior of underground mining and ensures the acquisition of precursor information of coal and gas outburst. The simulation experiment of coal and gas outburst in rock cross-cut coal uncovering was successfully carried out by using this experimental system. The real-time changes of temperature,gas pressure,solid pressure and acoustic emission data were monitored during the experiment,which provided the scientific experimental data for studying the mechanism,prediction method and control technology of coal and gas outburst.