Coal gangue slurry overburden balanced grouting and filling method for pre-fracturing hard rock stratum

By constructing fracturing boreholes and using hydraulic fracturing technology within thick and hard rock strata, the problems of balanced grouting and subsidence control in thick and hard rock strata, which were not addressed in existing technologies, have been solved, achieving controllable grouting volume and controllable subsidence.

CN116816429BActive Publication Date: 2026-07-10CHINA UNIV OF MINING & TECH
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
CHINA UNIV OF MINING & TECH
Filing Date
2023-07-17
Publication Date
2026-07-10

AI Technical Summary

Technical Problem

In coal mining, the ultimate fracture step of thick and hard rock strata is large, which leads to the rock strata below the grouting layer not being fractured. The grouting space is limited, and the grouting system cannot supply in time, causing the key overburden layer to become unstable and the surface to subside rapidly. Existing methods increase the flow rate of the surface grouting pump, resulting in problems such as excessive load on the surface pumping station and blockage of the filling borehole.

Method used

The method of uniform grouting and filling of coal gangue slurry overburden in pre-fracturing hard rock strata is adopted. By constructing the first and second fracturing boreholes in the thick and hard rock strata, fracturing fractures are formed along the dip and strike. Steel casings and quick-setting cement are installed in the boreholes for fixation. Combined with hydraulic fracturing technology, uniformly fractured fracturing fractures are formed to control rock strata collapse and ensure the balance between grouting volume and settlement control.

Benefits of technology

The first and second fracturing boreholes were drilled in thick, hard rock strata to form fracturing fractures along the dip and strike. Steel casings and quick-setting cement were installed in the boreholes for fixation. Combined with hydraulic fracturing technology, uniformly fractured fracturing fractures were formed to control rock strata collapse and ensure a balance between grouting volume and settlement control.

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Abstract

The present application relates to the field of coal mine filling mining, in particular to a coal gangue slurry overburden balanced grouting filling method for pre-fracturing hard rock stratum, a plurality of first fracturing cracks along the strike are fractured in the thick hard rock stratum along the inclination at intervals, the inclination construction range of the first fracturing cracks is between the intersection of the caving line and the grouting horizon and the inclination boundary of the coal mining face, a plurality of second fracturing cracks along the inclination are fractured in the thick hard rock stratum along the strike at intervals, the range of the second fracturing cracks along the inclination is between the inclination boundary of the coal mining face, and the fracturing cracks do not exceed the top boundary of the thick hard rock stratum, and a certain thickness of buffer zone is reserved. Thus, the strike breaking position and the inclination breaking position of the thick hard rock stratum are controlled, and then the control of the separation of the grouting horizon is realized, and balanced grouting is realized. The present application can best weaken the thick hard rock stratum on the basis of reducing the hydraulic fracturing engineering quantity as much as possible to be suitable for the overburden separation grouting filling engineering.
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