Method for locating and installing deep soft rock geostatic stress testing device

Abstract

The invention discloses a method for locating and installing a deep soft rock geostatic stress testing device. According to the method, a stress sensing column is manufactured, the stress sensing column is a cement concrete cylinder comprising two three-directional pressure boxes, and the center of each cubic pressure box is located on the medial axis of the cylinder; the front end of a push rod is connected with the stress sensing column, an angle testing device is installed, rotation angle and length of the stress sensing column are recorded when the push rod is pushed from a hole mouth to a tested point at the hole bottom, and accurate data necessary for stress resolving can be obtained. According to the method, no sharp protrusion exists at the front end or the side face of the stress sensing column, the hole wall will not collapse easily in the pushing process, relative positions of a pair of three-directional pressure sensors are fixed through the stress sensing column, the two three-directional pressure sensors will not move or rotate relatively in the pushing process, and the accuracy for calculating the geostatic stress of the tested point can be ensured.

Description

technical field [0001] The invention belongs to the technical field of geotechnical measurement, and in particular relates to a method for positioning and installing a deep soft rock geostress testing device. Background technique [0002] The safe construction of coal mine roadway is inseparable from the effective monitoring of the stress of surrounding rock. In the deep broken and weak surrounding rocks of coal mines, it is very difficult to effectively test the in-situ stress with the commonly used testing methods. Taking the hydraulic fracturing method widely used in hard rock as an example, it is essentially a two-dimensional stress measurement method, and its borehole packer needs to have good water tightness under high water pressure, which is critical to the integrity of the rock mass. It is not suitable for broken and weak rock mass with developed joints and fissures in deep coal mines. Another common test method used in hard rock is the stress relief method. Beca...

AI Technical Summary

Problems solved by technology

When applying this method to engineering practice, because soft rock has some characteristics different from those tested in hard rock, for example, since the surrounding rock is mostly soft rock such as sandstone, mudstone and clastic limestone, the depth of horizontal drilling When pushing the sensor (three-way pressure box), the cube-shaped metal shell is easy to cause damage to the hole wall, which will affect the pushing of the sensor in severe cases

On the other hand, due to the long push distance (sometimes up to hundreds of meters), the sensor may be twisted due to falling blocks and insufficient rigidity of the push rod during the push process.

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