Rock true triaxial pressure chamber with changeable principal stress direction when unloading

Abstract

Disclosed is a rock true triaxial pressure chamber. Four self-balance pistons which are arranged crosswise are disposed on a wall of the chamber. Each piston has a pressure cavity and a backpressure cavity, wherein the pressure cavity is attached to the pressure chamber through an external oil-way provided with a one-way valve; and the backpressure cavity is respectively attached to the atmosphere and a hand pump for transposition through a pipeline and the one-way valve. The self-balance pistons are provided with a pressure control system which reliefs pressure of the external oil-way of the piston's pressure cavity through the hand pump. An EDC controller receives feedback signals of a pressure transducer and a force transducer and outputs a control command to a Moog servo valve. According to the command, the servo valve controls the external oil-way for oil supply of an actuator and adjusts the pressure on the pistons. The advantage of original two-hardness one-softness true triaxial pressure chamber is maintained in the invention. On this basis, a self-balance to non-self-balance transition function is added in the true triaxial pressure chamber provided by the invention, thus making up the insufficiency that the original true triaxial pressure chamber can only unload hydrostatic pressure and realizing unloading of complete stress path.

Description

technical field [0001] The invention relates to a deep mining mechanics simulation test device, in particular to a rock true triaxial pressure chamber in which the principal stress direction can be changed during unloading on a rigid-flexible mixed rock true triaxial testing machine. Background technique [0002] Natural rock and soil materials are usually under three-dimensional stress conditions in the in-situ state, using three principal stresses (σ 1 ,σ 2 , σ 3 ) to describe the stress state of the original rock. For this reason, a true triaxial testing machine is often used to simulate σ 1 ≥σ 2 ≥σ 3 Rock mechanical behavior under stress conditions. In order to facilitate the application of loads in three directions orthogonal to each other, true triaxial specimens are usually processed into cubes or cuboids. A true three-axis loading system is composed of loading units that are orthogonal to each other in the x, y, and z directions, that is, σ x , σ y , σ z co...

AI Technical Summary

Problems solved by technology

[0003] The object of the present invention is to provide a true triaxial testing machine with a rock true triaxial pressure chamber whose main stress direction can be changed during unloading, aiming at the defect that the unloading path capacity of the above-mentioned self-balancing true triaxial pressure chamber is insufficient for deep rock mass excavation. Axial pressure chamber to solve the problem of insufficient unloading stress path

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