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Method and device for testing geo-stress in deep soft rock based on flow stress restoration principle

A technology of ground stress and measurement method, which is applied in the direction of measuring device, measurement of frequency change force by measuring the frequency change of the stressed vibrating element, force sensor in the hole of the force-bearing structure, etc., can solve the problem of ineffective testing of ground stress, etc. question

Inactive Publication Date: 2012-08-08
INST OF ROCK AND SOIL MECHANICS - CHINESE ACAD OF SCI +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These observation devices and methods can only measure the pressure in one direction, so none of them can effectively test the ground stress of a certain measuring point.

Method used

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  • Method and device for testing geo-stress in deep soft rock based on flow stress restoration principle
  • Method and device for testing geo-stress in deep soft rock based on flow stress restoration principle
  • Method and device for testing geo-stress in deep soft rock based on flow stress restoration principle

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] Embodiment 1, the three-way pressure box 1, 2 is a cube, its edges are made of high-strength steel, and the end face is a deformable steel elastic diaphragm 9, such as image 3 As shown, two steel cylinders 6 are fixed under the elastic diaphragm 9 (that is, the inner side of the three-way pressure box 1, 2), and a steel string 7 is fixed between the two steel cylinders 6, and a steel string 7 is sleeved on the steel string 7. The coil 8 is connected to the wire 4 . The wire 4 is connected with the reading instrument 5 . The structure is a vibrating wire structure known in the field of measuring instruments. When the elastic diaphragm 9 is bent under pressure, it drives the displacement of the cylinder 6, making the steel string 7 elongate or shorten, and changing its natural frequency. The reading instrument 5 is a frequency meter. By measuring the natural frequency of the steel string 7, the deformation value of the elastic diaphragm 9 can be obtained, and the pressu...

Embodiment 2

[0051] Embodiment 2, the three-way pressure box 1, 2 is a cube, its edges are made of high-strength steel, and the end face is a deformable elastic diaphragm 10, such as Figure 4 As shown, a resistance strain gauge 11 is fixed in the center of the bottom of the elastic diaphragm 10 (that is, the inner side of the three-way pressure box 1 ). The resistance strain gauge 11 is connected with the reading instrument 5 through the data line 4 . The resistance strain gauge 11 is well known in the field of measuring instruments. When the elastic diaphragm 10 is bent under pressure, the resistance strain gauge 11 is extended or shortened to change its resistance. The reading instrument 5 is an ammeter. By measuring the resistance of the resistance strain gauge 11, the deformation value of the elastic diaphragm 10 is obtained, and the pressure applied on the end surface of the three-way pressure cell is calculated through the data curve calibrated in advance.

Embodiment 3

[0052] Example 3, using the method of the present invention to conduct stress tests at three measuring points in Pingdingshan No. 1 Mine. The test process is as follows: drill a hole at the side wall of the main roadway to a depth of about 10 meters, push the connecting rod fixed with two three-way stress boxes to the bottom of the drilled hole, and use vibrating wire pressure for the measurement part of the three-way pressure box The test structure, the wires are connected internally to the frequency meter outside the borehole through connecting rods. Seal the borehole and fill it with M25 concrete mortar. After 24 hours, the grout has solidified, and the pressure value is read from the frequency meter every 1 hour. After the data is stable for about 12 hours, the six pressure data measured by the two three-way pressure cells are substituted into the ground stress test. In the principle formula, the equation is solved to obtain the ground stress state at the test point. The...

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Abstract

The invention discloses a method and device for testing a geo-stress of a deep soft rock. The device comprises a connecting rod; two three-direction pressure boxes are adjacently fixed on the connecting rod; the three-direction pressure box is provided with three vertical working surfaces; a direction cosine of any two working faces among the two three-direction pressure boxes is not 1; a device for measuring a normal pressure stress is mounted on each working face of the two three-direction pressure boxes; and the device is connected with a reading instrument outside a drilling hole through a data wire. A geo-stress testing method comprises the following steps of: sending the two three-direction pressure boxes to a test point after drilling; grouting the drilling hole and sealing the drilling hole after the drilling hole is entirely filled; and after slurry is solidified, substituting six pressure data measured by the two three-direction pressure boxes into a geo-stress testing principle formula after the data is stable, so as to obtain the geo-stress at the test position. With the adoption of the method, a stress value inside surrounding rocks can be directly observed, and observation data can be obtained for a long time. Therefore, the method and device provided by the invention is good for researches of coal deep rock geo-stress and the stability of a surrounding rock.

Description

technical field [0001] The invention belongs to the technical field of geotechnical measurement, and in particular relates to an in-situ stress test method suitable for deep soft rock, and also relates to an observation device used in the test method. [0002] Background technique [0003] Most of the deep surrounding rocks in coal mines are broken and weak, with low mechanical strength. It is very difficult to effectively test the in-situ stress in such a soft surrounding rock with the commonly used test methods, and there are great limitations and measurement errors. Taking the hydraulic fracturing method widely used in water conservancy, hydropower and traffic tunnel engineering as an example, the borehole packer needs to have good water tightness under high water pressure, which puts forward strict requirements on the integrity of the rock mass. It is not suitable for broken and weak rock masses with deep joints and fissures in coal mines. Moreover, this method can on...

Claims

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Application Information

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IPC IPC(8): G01L1/10G01L1/22
CPCG01L1/22G01L1/10E21C39/00G01V1/00G01L5/0004G01L5/1627
Inventor 刘泉声卫修君张程远郭建伟郭春生杨战标
Owner INST OF ROCK AND SOIL MECHANICS - CHINESE ACAD OF SCI
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