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为了更真实地模拟煤岩在掘进巷道迎头等环境下的应力状态,研究三向应力环境下煤岩的损伤变形及瓦斯渗流情况,自主研发了真三轴气-固耦合煤体渗流试验系统。该装置主要由真三轴压力室、液压伺服系统、气体渗流系统和监测与控制系统组成,采用的试件尺寸为200 mm×100 mm×100 mm,可施加的最大轴压(σ1)为70 MPa、最大侧压(σ2)为35 MPa、最大侧压(σ3)为10 MPa、最大瓦斯压力为6 MPa。该装置具有以下特点:(1)σ1、σ2采用刚性压头加载,σ3采用柔性加载,三向应力分别独立加载;(2)设计了刚柔性压头及传压滑杆,使得σ1与σ2方向压头在同时加载过程中互不干扰;(3)通过伺服液压系统控制加载功能,使得装置性能稳定,应力与位移加载精确,易于控制;(4)气体渗流系统采用蜂窝孔对试件进行面通气,确保试件进气端瓦斯压力均匀分布;(5)采用多种高精度传感器进行监测,实时记录煤体所受应力值、变形量及瓦斯渗流量。用两种不同应力路径下的渗流试验对该系统准确性和可靠性进行了验证,结果表明,该装置性能稳定可靠。该装置可用于揭示煤与瓦斯在三向应力条件下的耦合作用机制,为防治瓦斯灾害及研究瓦斯抽采提供了可靠的试验基础。
In order to more truly simulate the stress state of coal and rock in heading tunnel environment and to study the damage deformation and gas seepage of coal rock under three-direction stress environment, a true triaxial gas-solid coupling coal seepage flow test system was independently developed. The device mainly consists of a true triaxial pressure chamber, a hydraulic servo system, a gas seepage system and a monitoring and control system. The specimen size used is 200 mm × 100 mm × 100 mm and the maximum allowable axial pressure (σ1) is 70 MPa , The maximum lateral pressure (σ2) is 35 MPa, the maximum lateral pressure (σ3) is 10 MPa and the maximum gas pressure is 6 MPa. The device has the following characteristics: (1) σ1, σ2 are loaded with rigid indenter, σ3 is loaded with flexibility, and the three directions stress are independently loaded; (2) The rigid and flexible pressure head and pressure transfer slide bar are designed so that σ1 and σ2 directions The pressure head does not interfere with each other during the loading process; (3) the loading function is controlled by the servo hydraulic system, so that the device performance is stable, stress and displacement are accurately loaded and controlled; (4) Ventilation, to ensure uniform distribution of gas pressure at the inlet end of the specimen; (5) the use of a variety of high-precision sensors for monitoring, real-time record of the stress suffered by coal, deformation and gas seepage flow. The accuracy and reliability of the system were verified by the seepage test under two different stress paths. The results show that the performance of the device is stable and reliable. The device can be used to reveal the coupling mechanism between coal and gas under three-dimensional stress conditions, and provides a reliable experimental basis for preventing gas disasters and studying gas drainage.