Geostress testing device and testing method used for trepanning stress relief method

Abstract

The invention discloses a geostress testing device and testing method used for a trepanning stress relief method. Stress relief can be carried out smoothly. The geostress testing device used for the trepanning stress relief method comprises a coring sleeve and a drill bit, and further comprises a conic and hollow conversion joint. The large-diameter end of the conversion joint is fixedly connectedwith one end of the coring sleeve, the small-diameter end of the conversion joint is fixedly connected with one end of the drill bit, and the large diameter of the conversion joint is larger than theouter diameter of the coring sleeve. During use, in the drilling process of the first step, the coring sleeve and the drill bit are fed into a drilled hole together already, and therefore it is guaranteed that the coring sleeve can definitely enter the drilled hole, and the situation that the coring sleeve is not prone to being fed into the drilled hole later, construction of conic holes is hard,and the stress relief process is hard to achieve are avoided.

Description

technical field [0001] The invention relates to the field of geostress testing, in particular to a geostress testing device and a testing method for a casing stress relief method. Background technique [0002] In-situ stress, also known as proto-rock stress, is generated due to geological tectonic movement and other reasons in the long geological age. The stress state in the crust is the sum of various origin stresses, mainly composed of gravity stress, tectonic stress, pore pressure, Coupled thermal stress and residual stress. In-situ stress is the fundamental force that causes the deformation and destruction of mining engineering surrounding rock and support, and produces mine dynamic phenomena. Among the many factors that affect the stability of mining engineering, in-situ stress is one of the most important and fundamental factors. With the continuous expansion of mining scale and the continuous increase of mining depth, the influence of in-situ stress becomes more and ...

AI Technical Summary

Problems solved by technology

[0017] ①The commonly used construction technology is to directly connect the mining drill pipe with the drill bit to drill the in-situ stress test hole. However, the diameter of the casing stress relief hole is generally 130mm, while the diameter of the mining drill pipe is generally 50 or 75mm, so in During the drilling process, the drill pipe will shake very badly. In addition, the underground geological conditions of the coal mine are poor, the lithology is complex, and the rock strength of each layer is different. Coupled with the high ground stress and the gravity of the drill bit itself, the drilled holes are often not straight , there will be some bending, so when the core is released at the end, it is generally difficult to smoothly send the core sleeve into the hole, the stress cannot be relieved smoothly, and the complete core cannot be taken out. This problem is particularly prominent when the depth is deep and the ground stress is large;

[0018] ②When the borehole construction is completed and the stress gauge is installed, the stress gauge needs to be sent to the bottom of the borehole. Since the field of view in the coal mine is not clear and the borehole is deep, it is impossible to see the situation in the hole. The stress gauge is sent into the hole. In this case, it is often impossible to accurately judge whether the stress gauge is installed in the small hole at the bottom of the hole, and whether the quality of the stress gauge installation is qualified. If the hole collapses, the resistance will increase and the stress will increase. The gauge may be unable to continue to advance due to falling stones, and the glue filled in the strain gauge will flow out in advance, resulting in the scrapping of the strain gauge and the drill hole, wasting manpower, material resources and financial resources;

[0019] ③The push rods used in the casing stress relief method are generally connected by threads. Due to the poor environment in coal mines, there are often coal ash and rock powder on the ground. In addition, there is often water flow during drilling, which will wet the coal powder and rock. powder, which makes the environment worse. The underground working space is generally narrow, and the push rod will inevitably touch the ground. Therefore, the screw thread of the push rod will be stained with wet coal powder and rock powder particles, which is difficult to clean off. At the same time, the thread is easy to wear , which will cause the thread to be difficult to screw on. At the same time, the thread must be screwed once every time a push rod is connected, which greatly restricts work efficiency, causes inconvenience to on-site work, and affects production.

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