Visual true triaxial hydraulic fracturing test device and method

Abstract

The invention discloses a visual true triaxial hydraulic fracturing test device and a visual true triaxial hydraulic fracturing test method. The visual true triaxial hydraulic fracturing test device comprises a vertical axial pressure loading system, a horizontal stress loading system, a confining pressure loading system and the like, wherein a hydraulic loading system adopts high-transparency oilto perform flexible servo loading on six surfaces of a rock sample, and a hydraulic loading system is mounted on a flexible loading surface to realize hydraulic fracture; in order to ensure the sealing performance of a cylinder body of a pressure chamber, oil leakage prevention elastic rubber sleeves are fixed at the contact parts of the vertical axial pressure loading system, the horizontal stress loading system and the pressure chamber; a water pressure loading system realizes hydraulic fracture through carrying out water injection on the flexible loading surface, and fracturing fluid is collected by means of a rigid water guide base plate; and a high-speed camera is used for collecting the crack propagation process of the sample in the visual pressure chamber. In addition, the visual true triaxial hydraulic fracturing test device can further complete a hydraulic fracturing test of a cylindrical sample under the condition of false triaxial loading, and meet the test requirements ofrock samples with different shapes.

Description

technical field [0001] The invention relates to a true triaxial test device, and more particularly relates to a visual true triaxial hydraulic splitting device and method capable of realizing samples of different shapes under mixed loading. Background technique [0002] Hydraulic splitting of rock mass refers to the phenomenon of cracking, damage expansion and even overall failure and instability when the rock mass produces a stress state exceeding its own limit under the action of fluid pressure, which is a typical water-rock coupling problem. In projects such as tunnel water inrush and hydropower dam water seepage, there are problems of hydraulic splitting of rock mass, causing serious disasters to construction and operation. At the same time, the application of hydraulic splitting technology has accelerated the rapid development of modern petroleum industry, shale gas exploitation, geothermal resource development, nuclear waste storage, coal seam mining and other fields, ...

AI Technical Summary

Problems solved by technology

[0004] The inventors found that there are mainly two types of true triaxial loading devices: one is the rigid loading type, and the three principal stresses are all loaded in a rigid way, but it is easy to produce the friction effect of the stress blank angle and the end face, and the visualization of the crack growth process cannot be realized; The second is the flexible loading type. At least two principal stresses are loaded by flexible hydraulic methods, but they cannot be applied to hard rock tests due to the small hydraulic loading capacity.

In addition, the true triaxial test device only conducts tests on cubic samples, and cannot perform false triaxial tests on cylinders, so the popular type is poor; at the same time, due to the tightness of the main pressure chamber of the true triaxial, it is impossible to observe the test in real time The expansion of cracks in the process

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