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Method for measuring ground stress

A technology of in-situ stress and principal stress, which is applied in the field of geo-stress measurement, can solve the problems of large test workload, far from each other, differences, etc., and achieve the effect of convenient and fast measurement, easy control and operation, and cost reduction.

Inactive Publication Date: 2008-04-16
南京银茂铅锌矿业有限公司
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Problems solved by technology

However, there are still many problems in the measurement of the ground stress by the Kaiser effect, which needs to be further studied. Among them, the most closely related to the actual production and the most critical problem is how to determine the direction of the ground stress.
In the past, when people used the Kaiser effect to measure the stress of the original rock, it was necessary to carry out all-round testing within the range of 180 degrees (generally sampling every 5 degrees), so the number of samples was large, the test workload was heavy, and the cost was high; at the same time, due to multi-period tectonic movements The structure of the rock mass has changed, and the size and direction of the tectonic stress or original rock stress in the region have changed in quantity and quality.
In the past, the Kaiser effect measurement of the original rock stress was sampled in the horizontal or vertical direction, so it is possible that none of the samples obtained is really in the direction of the principal stress, and the result obtained from this test should also be the in-situ stress. A component of the field, there will be a certain difference, even far from the real original rock stress value
It is these reasons that have greatly affected the practical application of the method of measuring the stress of the original rock by the Kaiser effect, and cannot give full play to its advantages of being simple, economical, and convenient for multi-point measurement to find the law of regional in-situ stress changes.

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Examples

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Embodiment 1

[0028] Embodiment 1 Determination of ground stress in a certain mine in Nanjing:

[0029] (1) Determination of the stress direction of a mine in Nanjing:

[0030] Table 1 shows the occurrence of joints and faults in a mine in Nanjing. Due to rock strata, fault F 2 and Joint J 1 The occurrences of the fault F are basically similar. According to geomechanics knowledge, the fault F 2 and Joint J 1 It cannot be an X-conjugate joint, so the fault F can be removed 2 and Joint J 1 . Take the strike line of the rock layer as the rotation axis, and rotate it to the horizontal position in the NW direction. The rotation angle is equal to the inclination angle of the layer of 75°, and the rock layer is restored to the original horizontal position. The yoke joint is J 3 and J 4 , they can be determined as plane X fractures. The acute angle bisector where these two groups of joints intersect is the maximum principal stress σ 1 The orientation of the obtuse angle bisector is the m...

Embodiment 2

[0046] Example 2: Determination of the in-situ stress of the ore body in the veinlet zone of Dachang Tongkeng Mine

[0047] (1) Determination of in-situ stress direction

[0048] According to the engineering geological analysis results of the veinlet belt in the middle section of -570m, it is known that the strike of the layer is N80°E, inclined to NW, and the dip angle is 25°. After the rock layer is restored to the original horizontal position and turned over, the paired X-conjugate joints J14 and J15 of the same order can be judged (see Table 5). The acute angle bisector where these two groups of joints intersect is the maximum principal stress σ 1 The orientation of the obtuse angle bisector is the minimum principal stress σ 3 The direction shown by the intersection line of the two joints is the intermediate principal stress σ 2 orientation. When the dip angle of the rock formation is 25°, the X conjugate joint J 14 and J 15 Rotate to SE direction, its rotation angle...

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Abstract

The present invention relates to a ground stress measuring method which comprises the following procedures: 1) the occurrence of joint and faultage are determined; the nearest sequent subjoint and fissure in the same sequence are drawn on a stereographic projection drawing; 2) a terrane lay uses the strike line as a rotating axis and rotates to the horizontal position towards the dip direction; the rotary angle is equal to a dip angle of the lay, and the strike line of the joint and fissure winding lay rotates to the horizontal state to find a conjugated X-shaped joint; then the conjugated X-shaped joint and lay in the horizontal state rotate to the original state; three directions of the ground stress are determined on the stereographic projection drawing; 3) samples are drilled along three directions of the ground stress and 5 to 7 samples are drilled along each direction; 4) the acoustic emission experiment of a rock sample is done indoors to have a Db4 small wave analysis on the acoustic emission signals of rock, thereby determining the acoustic emission Kaiser point of rock; the size of the ground stress is determined according to the acoustic emission Kaiser point of rock. The invention is small in sample quantity, low in cost, rapid in measuring progress of the ground stress, and accordingly more convenient and rapid in measurement of the ground stress.

Description

technical field [0001] The invention relates to a method for measuring ground stress, specifically a method for measuring ground stress by combining geomechanics with acoustic emission signal Db4 wavelet analysis technology Background technique [0002] Compared with the traditional stress relief method and hydraulic fracturing method, the rock acoustic emission Kaiser effect measurement of ground stress has the advantages of simplicity, intuition, and economy, and it is convenient for a large number of tests to find the regional ground stress change law. Therefore, this method is a promising method for geostress measurement. However, there are still many problems in the measurement of in-situ stress by Kaiser effect, which need to be further studied. Among them, how to determine the direction of in-situ stress is the most closely related to the actual production and the most critical. In the past, when people used the Kaiser effect to measure the stress of the original roc...

Claims

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Application Information

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IPC IPC(8): G01L1/00G01L1/10G01V1/00G01N29/04
Inventor 王方汉周小平杨海清曹维勤隆向阳卢萍张文如刘庆义
Owner 南京银茂铅锌矿业有限公司
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