Electromagnetic transient unloading test system and method

Abstract

The invention discloses an electromagnetic transient unloading test system and method, the device comprises two Hopkinson bars and a rock mass sample fixed between the Hopkinson bars, one ends of the Hopkinson bars are fixed, the other ends of the Hopkinson bars are provided with unloading assemblies, the Hopkinson bars are provided with strain gauges, and the strain gauges are connected with the super-dynamic strain gauge, the transient waveform memory and the data processing center in sequence; the unloading assembly comprises a rectangular steel frame, one side of the rectangular steel frame abuts against the Hopkinson bar, the other side of the rectangular steel frame abuts against the brittle bar, a bullet barrel and bullets are arranged in the inner space of the rectangular steel frame, and the bullets are the same as the rectangular steel frame in horizontal height and face the direction of the brittle bar; and the other side of the brittle rod abuts against the loading assembly. The Hopkinson bar device is adopted to simulate the transient unloading process, the change of the strain state and the transmission mode of stress waves in the unloading process are measured to be more accurate, in the research process of transient unloading, a bullet impacts a brittle bar at a high speed to damage the brittle bar, and the unloading efficiency is greatly improved.

Description

technical field [0001] The invention relates to the technical field of rock mass blasting tests, in particular to a test system and method for electromagnetic transient unloading. Background technique [0002] In the process of excavation and blasting of deep underground engineering, the process of blasting excavation of high ground stress rock mass is actually a process of transient unloading. Blasting excavation changes the geometric properties of underground rock mass, resulting in initial stress on the excavation surface. Rapid unloading, the displacement of the rock mass makes the rock mass displacement boundary conditions and load boundary conditions change sharply, so that the elastic strain energy stored in the rock and soil is released in a short time, thus forming an unloading stress wave. [0003] However, most of the current analysis and research on deformation problems caused by high ground stress blasting excavation are limited to numerical simulation and theor...

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Problems solved by technology

[0003] However, most of the current analysis and research on deformation problems caused by high ground stress blasting excavation are limited to numerical simulation and theoretical derivation. Numerical simulation has a great dependence on engineering rock mass parameters and involves many parameters. It requires a large number of samples to measure parameters in the laboratory and the laboratory, and the cost is relatively high; the theoretical derivation involves multiple disciplines such as damage mechanics and fracture mechanics, and the theoretical analysis is difficult

However, the existing test system for simulating excavation and unloading has a relatively slow unloading rate, and cannot quickly unload the load on the geotechnical model.

[0004] At present, the similar simulation methods are used to study the dynamic unloading effect of rock mass: (1) the transient unloading and loosening simulation test system for the excavation of the structural surface of the underground cavern (Chinese patent application number: 201510203951.3), the device is loaded and unloaded through a lever The component realizes the rapid unloading of the load on the surrounding rock model of the excavated underground cavern with structural surfaces, but the structure of the device is relatively complicated; (2) A test device and method for testing the dynamic unloading effect of rock mass (China Patent application number: 201610331042.2), the device realizes rock mass unloading with different confining pressure, different lateral pressure coefficients and different unloading speeds through the pressure relief device, but the device cannot quickly unload the load

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