Stress gradient loading test apparatus and method of accurately determining loading energy

A stress gradient loading test apparatus comprising a rock mechanical tester, an upper pressure bearing plate, a specimen fixing device, a stress transfer device, and a simulation specimen, in which the specimen fixing device is disposed on a test bench of the rock mechanical tester, wherein the simulation specimen is placed between side baffle plates of the specimen fixing device, the stress transfer device is pressed on an upper surface of the simulation specimen, and the upper pressure bearing plate is pressed above the stress transfer device;

• the specimen fixing device is in a U shape, including a bottom baffle plate and two side baffle plates;
• the stress transfer device includes a plurality of plate-like high strength materials which are arranged in combination according to magnitude of stiffness, and the plurality of plate-like high strength materials together transfer a loading pressure of the upper pressure bearing plate;
• a simulation roadway is opened in the simulation specimen, a plurality of strain gauges are disposed on top and bottom plates and a side wall of the simulation roadway, and a stress sensor is disposed on an upper part of the simulation specimen;
• a loading system of the rock mechanical tester, the strain gauge, and the stress sensor are connected with a computer separately;
• the stress transfer device is mounted by fitting the side baffle plates of the fixing device, and a contact surface between the stress transfer device and the side baffle plate is smooth, and an indenter of the rock mechanical tester is pressed on the upper pressure bearing plate;
• and the upper pressure bearing plate is a solid steel plate with a thickness smaller than a thickness of the side baffle plate of the specimen fixing device.