Physical model test system for simulating strong mine tremors based on joint monitoring of microseismic and acoustic emission and test method thereof
A physical model test system for simulating strong mine tremors based on joint monitoring of MS and AE and a test method thereof, comprising: positioning and drilling a circular hole in a load plate according to design positions of all-fiber MS and AE sensors; mounting limiting rings concentric with the circular holes outside the load plates; bonding seismic isolation antifriction plates on inner walls of the load plates; manufacturing model body through layered compaction method to a height reaching one of the circular holes; inserting wave conducting rod into the limiting ring and the circular hole sequentially to a specified depth of the model body; filling with analogue materials and compacting; detaching the limiting rings after the model body is stably loaded, connecting the all-fiber MS sensors to exposed portion of the wave conducting rod, and bonding the AE sensors to outer sidewalls of the wave conducting rods.
1 . A physical model test system for simulating strong mine tremors based on joint monitoring of microseismic (MS) and acoustic emission (AE), comprising a combined-type visualization reaction combined rack apparatus, hydraulic jacks are mounted on an inner wall of the combined-type visualization reaction combined rack apparatus, and are configured to drive load plates applying a load to a model body; wherein, the physical model test system further comprises wave conducting rods, a built-in portion of each of the wave conducting rods is inserted inside the model body, an exposed portion of the each of the wave conducting rods extends to an outer side of the load plates, all-fiber MS sensors are installed at ends of exposed sections of the wave conducting rods, and AE sensors are attached to designated positions in a plane of an outer wall of the exposed section of the each of the wave conducting rods; the all-fiber MS sensors are connected to an all-fiber MS monitoring system, and the AE sensors are connected to an AE system; positions of the all-fiber MS sensors and the AE sensors in space are not coplanar; combined use of the all-fiber MS monitoring system and the AE system, wherein the all-fiber MS and the AE systems are configured to maximally capture vibration signals generated by overburden breaking, and positioning results obtained thereby may mutually verify each other to ensure that test results are realistic and reliable; and, monitoring elements for monitoring stress, strain, and displacement are further provided in the model body, and the monitoring elements are connected to a corresponding test system, respectively;
wherein each of the load plates is manufactured by cutting a uniform and flat thick steel plate, and is manufactured to be a shape comprises any one of a sheet-type load plate, a block-type load plate, and an integral-type load plate; wherein,
the integral-type load plate is located at a bottom of the model body; the sheet-type load plates are located on left, right, and rear side surfaces of the model body, respectively; and, the block-type load plates are located on a top surface of the model body.
2 . The physical model test system for simulating strong mine tremors based on joint monitoring of MS and AE according to claim 1 , wherein seismic isolation antifriction plates are provided on inner walls of the load plates.
3 . The physical model test system for simulating strong mine tremors based on joint monitoring of MS and AE according to claim 1 , wherein circular holes are drilled in the load plates, and detachable-type limiting rings that are concentric with the circular holes are provided on outer surfaces of the load plates and are fixed by limiting bolts; and, a diameter of each of the circular holes is greater than an inner diameter of each of the limiting rings, and the inner diameter of the each of the limiting rings is greater than an outer diameter of the each of the wave conducting rods.
4 . The physical model test system for simulating strong mine tremors based on joint monitoring of MS and AE according to claim 1 , wherein the each of the wave conducting rods is of a regular prism shape, and a width of one of four outer sidewalls of the each of the wave conducting rods is greater than a diameter of each of the AE sensors, and the exposed portions of the wave conducting rods are processed with threads matching the all-fiber MS sensors.
5 . The physical model test system for simulating strong mine tremors based on joint monitoring of MS and AE according to claim 1 , wherein acrylic plates are provided on a front surface of the model test rack, and are closely attached to the front surface of the model body.
6 . The physical model test system for simulating strong mine tremors based on joint monitoring of MS and AE according to claim 1 , comprising sheet-type latticed-type steel bridges that are hollow in the middle and closed at two ends and are connected by bolts, a pull-out-type front wall, and an acrylic plate, wherein the latticed-type steel bridges may be freely assembled to adapt to coal seams mining model tests under different similar scales; the pull-out-type front wall of the model test rack is provided inside the assembled steel bridges, and is to provide a passive constraint for the model body and reserves an operation space for the simulation of the coal seam mining; and the acrylic plate is provided in a groove of the assembled steel bridges and is configured for providing a passive constraint for the model body and implementing visualized observation of the simulation of the overburden breaking.
7 . A test method by using a physical model test system for simulating strong mine tremors based on joint monitoring of MS and AE according to claim 1 , comprising:
choosing a coordinate origin, and establishing a space rectangular coordinate system;
determining a spatial layout plan of all-fiber MS sensors and AE sensors; and determining three-dimensional (3D) coordinates of the all-fiber MS and AE sensors by using the established space rectangular coordinate system as a reference;
drilling circular holes on load plates according to the determined spatial layout plan, and installing detachable-type limiting rings concentric with the circular holes outside the load plates and securing by limiting bolts;
manufacturing a model body by using a layered compaction air-drying method with a height to reach one of the circular holes, then inserting wave conducting rods sequentially into the limiting rings and the circular holes of the load plates to a specified depth inside the model body, and filling with analogue materials and compacting;
bonding the AE sensors at the specified position in outer sidewalls of the wave conducting rods, and screwing the all-fiber MS sensors into ends of the wave conducting rods;
determining whether a MS-AE positioning error meets an accuracy requirement by carrying out a knock positioning test; and
if the accuracy requirement is met, then performing the model test, and monitoring and acquiring MS and AE events in real time; otherwise, checking and repairing an all-fiber MS monitoring system, an AE system, and corresponding sensors, and then carrying out the knock positioning test again until the positioning error meets the accuracy requirement.