Test piece holder for coalbed fracturing

A test piece holder for coalbed fracturing, comprising a pressure chamber with a circular tube structure, wherein a test piece is mounted in a center of an inner cavity of the pressure chamber;

• and first sliding rods, second sliding rods, third sliding rods, fourth sliding rods, fifth sliding rods and oil cylinders which are symmetrically arranged at upper and lower ends of the test piece and sequentially connected, wherein the second sliding rod is in sliding fit with the pressure chamber, diameters of the first sliding rod, the third sliding rod and the fourth sliding rod are all smaller than a diameter of the second sliding rod, the fifth sliding rod is extended into the respective corresponding oil cylinder, and a side wall of the oil cylinder is provided with an axial pressure channel for connecting with an axial pressure;
• and two confining pressure channels are symmetrically formed on a side wall of the pressure chamber for connecting with a confining pressure, an isolation rubber sleeve is wrapped outside the two first sliding rods and the test piece, and a sealing ring is arranged between the isolation rubber sleeve and the first sliding rod to prevent hydraulic oil from infiltrating into the test piece through upper and lower ends of the isolation rubber sleeve;
• and
• each of the upper and lower ends of the test piece is provided with an electrode needle and a gas-guide and liquid-guide conducting bolt, one end of the electrode needle abuts against the test piece and the other end of the electrode needle coaxially penetrates through the first sliding rod, the second sliding rod and the third sliding rod sequentially and then is inserted into a blind hole of the fourth sliding rod, one end of the gas-guide and liquid-guide conducting bolt is connected with the electrode needle and the other end of the gas-guide and liquid-guide conducting bolt transversely penetrates out of the fourth sliding rod, a diameter of the electrode needle is smaller than an inner diameter of the sliding rod through which the electrode needle penetrates to form a water-gas channel, two water-gas channels are both tightly attached to the test piece, the gas-guide and liquid-guide conducting bolt has a hollow rod structure, an inside end of the gas-guide and liquid-guide conducting bolt located above is communicated with the water-gas channel and an outside end of the gas-guide and liquid-guide conducting bolt located above is a water-gas outlet, an inside end of the gas-guide and liquid-guide conducting bolt located below is communicated with the water-gas channel and an outside end of the gas-guide and liquid-guide conducting bolt located below is respectively provided with a gas inlet and a water inlet, the pressure chamber is capable of being mounted on an insulating fixed base by horizontally rotating by 360°, and the pressure chamber is made of a material meeting CT scanning requirements.