A test method for simulating rock underground excavation by air pressure unloading

Abstract

The invention relates to the field of simulation tests for underground rock excavation, and aims to provide a test system and method for simulating underground rock excavation by air pressure unloading. It includes three external loading systems perpendicular to each other and an internal loading and unloading system located in the sample cavity; the latter includes a cylindrical film airbag after inflation, and the film airbag is connected to the air compressor through the air pipe; the X, Y Or any screw adjusting screw in the Z-axis direction has a hollow tubular structure, and the gas delivery tube is installed in the screw adjusting screw; the film airbag can be inserted into the sample cavity when it is not inflated, and it will fill the sample cavity after inflating to apply internal loads; the load cells in each external loading system are respectively connected to the computer through signal lines. The invention can simulate the excavation of any cross-section shape, realize instantaneous unloading or step-by-step unloading, and truly simulate the actual excavation process of different construction methods; it can simulate the collapse of the surrounding rock of the shallow tunnel and the rockburst of the deep tunnel under the condition of high ground stress .

Description

technical field [0001] The invention belongs to the field of rock underground excavation simulation tests, and relates to a rock excavation simulation test system, in particular to an air pressure unloading simulation test system and method for rock underground excavation. Background technique [0002] At present, a large number of infrastructure construction in my country involves underground rock excavation projects, such as urban subways, highway tunnels, railway tunnels and hydropower projects, etc. Underground rock excavation will change the original stress state of the surrounding rock, and the stability of the surrounding rock will also be affected. impact, some projects even caused casualties. The correct excavation method and effective protective measures help to reduce the damage caused by the instability of the surrounding rock. The rock excavation process is essentially an unloading process. Accurately grasping the mechanical response during the rock unloading pro...

AI Technical Summary

Problems solved by technology

At present, most of the relevant laboratory tests commonly used are to simulate excavation by loading the external boundary of the underground cavern model. Since the rock has different mechanical responses under loading and unloading conditions, it is debatable whether the experimental results obtained through loading experiments are practical; some The test uses the unloading method to simulate the excavation, but due to the influence of the experimental method, the unloading section of the model is usually a plane, which is quite different from the actual underground cavern section. Both engineering practice and theoretical calculations show that the stress redistribution of surrounding rock is affected by the shape of the excavated section. The impact is significant, and the results of the above unloading experiments are still far from the actual application

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