1. A ground double-open-hole combined monitoring method for internal movement of a water-rich stratum mining rock stratum is characterized by comprising the following steps:

a. selecting a rock stratum movement monitoring position on the earth surface above a working surface to be recovered, and arranging two adjacent vertical monitoring drill holes which are bare holes and are numbered as a bare hole A and a bare hole B;

b. determining the development height Hd of a water flowing fractured zone according to the thickness M of a coal seam at the monitoring drilling position, the burial depth Hc of the coal seam, the depth Hs of a bottom boundary of a water-rich layer needing to be prevented and controlled and lithology; the method comprises the following steps that a bare hole A is a monitoring borehole for rock stratum movement of a bending subsidence zone above a water-flowing fractured zone, the construction depth Ha of the bare hole A is determined as the coal seam burial depth Hc minus the development height Hd of a water-flowing fracture, and then the thickness h of a protection section for isolating the water-flowing fractured zone from the bottom boundary of a water-rich layer is subtracted, namely Ha is Hc-Hd-h; determining the bare hole B as a monitoring borehole of rock stratum movement in the range of the water-flowing fractured zone, wherein the maximum depth can reach the deepest rock stratum burial depth Hz needing to be monitored, namely the bottom interface burial depth of the water-flowing fractured zone, placing a casing on the rock stratum above the water-flowing fractured zone to block a water-rich layer, and not setting a monitoring point;

c. determining the diameter of the bare hole section of the monitoring drilling hole according to the outer diameter D of a placed in-hole monitoring instrument, and determining that the diameter D of the bare hole section is more than or equal to 2.5 times of the outer diameter D of the in-hole monitoring instrument, but the diameter D of the bare hole section of the monitoring drilling hole is not more than 120 mm;

d. the naked hole A is a whole-section naked hole; a rock stratum movement monitoring drilling hole in the range of the water flowing fractured zone, namely a naked hole B, is divided into I, II two sections, the section from the drilling of an orifice to the depth Hs of a bottom boundary which needs to be prevented and controlled and is rich in a water layer is taken as the section I with the range of 10m deep, a sleeve is placed in the section I drilling hole to isolate a water-containing layer, and the section II is taken from the bottom of the hole to the bottom of the hole;

e. installing a plurality of in-hole monitoring instruments on the bare hole sections in the bare hole A and the bare hole B respectively, guiding a steel wire rope of the monitoring instrument in the connecting hole to each monitoring drilling hole opening, guiding the steel wire rope to the hole opening combined collection box through a guide pulley and a guide groove with a support at the hole opening, connecting a collection encoder in the hole opening combined collection box, and connecting the collection encoder with a data storage and display screen through a data line;

f. and in the working face recovery process, carrying out rock stratum movement monitoring.

2. The monitoring method according to claim 1, wherein: in the step a, the linear spacing distance S between two adjacent vertical monitoring drilling holes is more than 5m but less than or equal to 10 m; the monitored borehole aperture elevation difference is less than 0.3 m.

3. The monitoring method according to claim 1, wherein: in the step a, in the drilling construction process of the monitoring drilling hole, the deviation of the monitoring drilling hole is corrected once every 50m of drilling, and the deviation of the monitoring drilling hole per hundred meters is controlled to be not more than 0.3 degrees.

4. The monitoring method according to claim 1, wherein: in step b, h takes the value of 20 m.

5. The monitoring method according to claim 1, wherein: in step c, d is 30-40 mm.

6. The monitoring method according to claim 1, wherein: in step D, the diameter of the section I drilled hole is D_LSelecting the sleeve with the inner diameter Dt0 equal to the diameter D of the bare hole of the section II, and the outer diameter Dt1 equal to the inner diameter Dt0 plus the wall thickness b, D_LGreater than Dt1 by at least 50 mm; and (3) adopting cement paste to solidify an annular space between the outer wall of the casing and the drilled hole, and constructing a bare hole II section with the diameter of D downwards to the depth Hz after the cement paste is solidified for 72 hours.

7. The monitoring method according to claim 6, wherein: in the step d, the cement paste for setting the annular space between the casing and the hole wall is formed by mixing loose dry cement and water, wherein the loose dry cement is ordinary portland cement, the strength grade is 42.5R, and the water cement ratio of the cement paste is 0.55: 1.

Background

The moving damage of overburden strata or rock mass after mining of mines is the root cause of a series of mine disasters and environmental problems such as underground severe mine pressure, water inrush, surface subsidence and the like. The overburden stratum movement monitoring after mining is carried out, and the method is the basis for mastering the movement rule of the stratum and solving a series of mining damage problems caused by mining. The development of engineering actual monitoring of rock stratum movement is an important means for verifying theoretical correctness and improving disaster prevention effect.

The actual engineering monitoring of rock stratum movement usually adopts ground construction drilling, anchor fluke measuring points are installed at different rock stratum positions in the drilling, and the anchor fluke measuring points are fixed on the wall of the drilling hole, connected to the hole opening through a steel wire rope and connected with a collecting instrument to realize the monitoring of the internal movement. The existing monitoring methods all need to construct a bare hole, namely a hollow borehole with no hole sealed inside. The bare hole mainly provides free movement space for conveying the steel wire rope. Therefore, formation mobility monitoring using open holes in the ground is an important mode. However, after the coal seam is mined, the overburden may move and break, forming fractures and varying degrees of fracture in the formation. According to the difference of stratum fracture degrees, in the field of mining engineering, an overlying rock stratum is divided into an caving zone, a fracture zone and a bending subsidence zone from bottom to top. The caving zone and the fissure zone are also called as water flowing fissure zones together, and are main areas for movement and flowing of water and gas on the top plate after coal seam mining. If the stratum contains a water-bearing layer with stronger water-rich property and the water-bearing layer is communicated with the water flowing fractured zone, the obvious water outlet phenomenon of the working surface can be caused. Therefore, in the rock stratum movement monitoring, the particularity of the water-rich layer condition needs to be considered, and the key of rock stratum movement monitoring under the water-rich layer condition is to prevent the monitoring borehole from becoming a channel for communicating a water-flowing fractured zone with the water-containing layer.

After the conventional rock stratum movement monitoring drilling hole is constructed, a monitoring instrument is usually installed on the wall of a bare hole, and hole sealing treatment is not carried out. For shallow coal seams, a water-conducting fractured zone may develop directly to the ground, and the fractured zone is necessarily communicated with a water-bearing stratum, so that monitoring has a large risk of water damage to a roof, and the monitoring is usually not recommended. However, for the condition that the stratum has a water-rich aquifer and is higher than the height of the water-flowing fractured zone, a drilling and non-hole-sealing bare hole monitoring mode is adopted, so that the great potential safety hazard that the water-rich aquifer is communicated with the water-flowing fractured zone through a hollow drilling hole to cause water inrush in the well inevitably exists. Therefore, the internal movement monitoring of the rock stratum is carried out under the condition of the aquifer with strong water-rich property, so that the monitoring purpose is considered, and the safety problem caused by the fact that the monitoring drill hole is communicated with the aquifer on the working surface is guaranteed.

Disclosure of Invention

Aiming at the problems and the defects of the existing method, the ground drilling monitoring method for mining rock stratum movement when the aquifer with strong water-rich property exists in the stratum is provided, on the basis of meeting the monitoring target, the safety monitoring in the bare hole is realized through the smallest aperture and hole depth, the secondary flood problem is avoided, and the application range of rock stratum movement monitoring in the drilling hole is expanded.

In order to achieve the technical purpose, the invention discloses a ground double-bare-hole combined monitoring method for internal movement of a water-rich stratum mining rock stratum, which comprises the following steps:

a. selecting a rock stratum movement monitoring position on the earth surface above a working surface to be recovered, and arranging 2 adjacent vertical monitoring drill holes which are bare holes and are numbered as a bare hole A and a bare hole B;

preferably, in step a, the linear separation distance S between two adjacent vertical monitoring borehole apertures is greater than 5m but less than or equal to 10 m; the monitored borehole aperture elevation difference is less than 0.3 m.

Preferably, in the step a, in the drilling construction process of the monitoring drilling hole, the deviation of the monitoring drilling hole is corrected once every 50m of drilling, and the deviation of the monitoring drilling hole per hundred meters is controlled to be not more than 0.3 degrees.

b. Determining the development height Hd of a water flowing fractured zone according to the thickness M of a coal seam at the monitoring drilling position, the burial depth Hc of the coal seam, the depth Hs of a bottom boundary of a water-rich layer needing to be prevented and controlled and lithology; the method comprises the following steps that a bare hole A is a monitoring borehole for rock stratum movement of a bending subsidence zone above a water-flowing fractured zone, the construction depth Ha of the bare hole A is determined as the coal seam burial depth Hc minus the development height Hd of a water-flowing fracture, and then the thickness h of a protection section for isolating the water-flowing fractured zone from the bottom boundary of a water-rich layer is subtracted, wherein h can be 20m generally, namely Ha is Hc-Hd-h; determining the bare hole B as a monitoring borehole of rock stratum movement in the range of the water-flowing fractured zone, wherein the maximum depth can reach the deepest rock stratum buried depth Hz required to be monitored, generally the bottom interface buried depth of the water-flowing fractured zone, placing a casing on the rock stratum above the water-flowing fractured zone to block a water-rich layer, and not setting a monitoring point;

c. the diameter of the bare hole section of the monitoring drilling hole is determined according to the outer diameter D of a placed in-hole monitoring instrument, D is generally 30-40mm, the diameter D of the bare hole section is determined to be more than or equal to 2.5 times of the outer diameter D of the in-hole monitoring instrument, but the diameter D of the bare hole section of the monitoring drilling hole is generally not more than 120 mm;

d. the naked hole A is a whole-section naked hole; a rock stratum movement monitoring drilling hole in the range of the water flowing fractured zone, namely a naked hole B, is divided into I, II two sections, the section from the drilling of an orifice to the depth Hs of a bottom boundary which needs to be prevented and controlled and is rich in a water layer is taken as the section I with the range of 10m deep, a sleeve is placed in the section I drilling hole to isolate a water-containing layer, and the section II is taken from the bottom of the hole to the bottom of the hole;

preferably, in step D, the diameter of the section I drilled hole is D_LSelecting the sleeve with the inner diameter Dt0 equal to the diameter D of the bare hole of the section II, and the outer diameter Dt1 equal to the inner diameter Dt0 plus the wall thickness b, D_LGreater than Dt1 by at least 50 mm; and (3) adopting cement paste to solidify an annular space between the outer wall of the casing and the drilled hole, and constructing a bare hole II section with the diameter of D downwards to the depth Hz after the cement paste is solidified for 72 hours.

Preferably, in the step d, the cement slurry used for sealing the casing is formed by mixing loose dry cement and water, wherein the loose dry cement is ordinary portland cement, the strength grade is 42.5R, and the water cement ratio of the cement slurry is 0.55: 1.

e. Installing a plurality of in-hole monitoring instruments on the bare hole sections in the bare hole A and the bare hole B respectively, guiding a steel wire rope of the monitoring instrument in the connecting hole to each monitoring drilling hole opening, guiding the steel wire rope to the hole opening combined collection box through a guide pulley and a guide groove with a support at the hole opening, connecting a collection encoder in the hole opening combined collection box, and connecting the collection encoder with a data storage and display screen through a data line;

f. and in the working face recovery process, carrying out rock stratum movement monitoring.

The data in the drill hole are collected in the mode, and the double-bare-hole combined monitoring of the rock stratum movement information is realized.

The beneficial technical effects of the invention are as follows: the method can realize the purpose of monitoring the movement of the interior of the mining rock stratum of the water-rich stratum, and realize the monitoring target of different layers of the whole stratum by respectively monitoring the rock stratum movement modes of different sections through double bare holes. Meanwhile, the condition that the stratum is rich in water which often occurs at present can be used for monitoring the movement of terranes in different depths, the problems of large aperture, long construction time and high drilling cost in single open hole monitoring are avoided, more importantly, the problem that the water inrush safety risk of the underground working face is increased due to rock migration monitoring can be avoided, and the unification of economy and safety is realized.

Drawings

FIG. 1 is a vertical dual-bare hole layout (cross-sectional view);

FIG. 2 is an enlarged view of a portion of the vertical dual bare hole of FIG. 1;

FIG. 3 is a combined monitoring device for mobile data inside a double-open-hole rock formation;

in the figure, (a) a top view; (b) a sectional view;

in the figure, 1-naked hole A; 2-bare well B; 3-a water-flowing fractured zone; 4-a fracture zone; 5-bending the sinking strip; 6-rich water layer; 7-in-hole monitoring instruments (i.e., in-hole monitoring points); 8-cement slurry solidified body; 9-a steel wire rope; 10-orifice joint collection box; 11-a guide pulley with a bracket; 12-a guide groove; 13-acquisition encoder; 14-a data line; 15-data storage, display screen.

Detailed Description

Specific drilling examples are further described below with reference to the accompanying drawings:

a ground double-bare-hole combined monitoring method for internal movement of a water-rich stratum mining rock stratum comprises the following steps:

as shown in fig. 1-2, a, selecting a monitoring drilling hole position above a working face to be recovered, wherein the monitoring drilling hole comprises a vertical bare hole A1 and a bare hole B2 which are adjacent to each other; the linear spacing distance S of two adjacent vertical monitoring drilling holes is more than 5m but less than or equal to 10 m; monitoring that the elevation difference of the drill hole orifices is less than 0.3 m; and in the drilling construction process of the monitoring drilling hole, the deviation of the drilling hole is corrected once every 50m of drilling, and the deviation of the monitoring drilling hole per hundred meters is controlled to be not more than 0.3 degrees.

b. Assuming that the thickness M of the coal seam at the monitoring drilling position is 4M, the burial depth Hc of the coal seam is 500M, the depth Hs of the bottom boundary of the water-rich layer 6 needing to be prevented and controlled is 300M, and the lithology is a medium-hard rock stratum, and determining the development height Hd of the water flowing fractured zone 3 to be 45.6M. The open hole A is a monitoring borehole for rock stratum movement of a bending subsidence zone 5 above a water diversion fractured zone 3, the construction depth Ha of the open hole A is the thickness of a protection section for isolating the water diversion fractured zone 3 from the bottom boundary of a water-rich layer 6 by subtracting the development height Hd of the water diversion fractured from the coal bed burial depth Hc and subtracting the thickness of the protection section from the bottom boundary of the water diversion fractured zone 3, and the thickness of the protection section is 20m, so that Ha is 500-45.6-20 is 434.4 m. The bare hole B is a monitoring borehole for rock stratum movement in the range of the water-flowing fractured zone 3, the maximum depth can reach the deepest rock stratum buried depth Hz of 480m which needs to be monitored, generally the bottom interface buried depth of the fractured zone 4, the water-rich layer 6 above the water-flowing fractured zone 3 is influenced by the protection of a casing, and a monitoring point is not arranged.

c. Monitoring the outer diameter of an in-hole monitoring instrument 7 placed in a drill hole to be about 40mm, wherein the diameter D of a naked hole section is more than or equal to 2.5 times of the outer diameter D of the in-hole monitoring instrument 7, namely at least 100mm, but the diameter D of the naked hole section is not more than 120mm generally;

d. monitoring the construction of the drilling, wherein the bare hole A is a full-section bare hole; the monitoring drilling of the rock stratum movement in the range of the water flowing fractured zone 3, namely the bare hole B needs to be divided into I, II two sections, from the drilling of the hole opening, the bottom boundary depth of the water-rich layer 6 is 300m, the range section with the depth of 10m is taken as the I section,i.e. the section I has a hole depth of 310m and the section II is below the hole bottom. Diameter of section I borehole is D_LAnd placing a sleeve in the section I drilling hole to isolate an aquifer, wherein the inner diameter Dt0 of the sleeve is consistent with the diameter of the section II naked hole and is 100 mm. The outer diameter Dt1 of the sleeve is equal to the inner diameter Dt0 plus the wall thickness b of the sleeve, and generally the wall thickness of the sleeve is 8mm, then Dt1 is equal to 116mm, D_LGreater than Dt1 by at least 50mm, and then at least 166 mm. Adopting cement slurry to solidify an annular space between the outer wall of the casing and the drill hole, forming a cement slurry solidified body 8 after the cement slurry in the hole is solidified for 72 hours, so that the casing is stable, and then downwards constructing a naked hole II section with the diameter of 100mm, namely a section with the hole depth of 434.4m to 480 m; the cement paste used for sealing the casing is formed by mixing loose dry cement and water, wherein the loose dry cement is ordinary portland cement, the strength grade is 42.5R, and the water-cement ratio of the cement paste is 0.55: 1;

as shown in fig. 1-3, e. installing a plurality of in-hole monitoring instruments 7 on the bare hole sections in the bare hole a and the bare hole B respectively, guiding the steel wire ropes 9 of the in-hole monitoring instruments 7 to each monitoring drilling hole, guiding the steel wire ropes 9 to the hole combined collection box 10 through the guide pulleys 11 and the guide grooves 12 with the supports at the holes, connecting the collection encoders 13 in the hole combined collection box 10, and connecting the collection encoders 13 with the data storage and display screen 15 through the data lines 14;

f. and in the working face recovery process, carrying out rock stratum movement monitoring.

The data in the drill hole are collected in the mode, and the double-bare-hole combined monitoring of the rock stratum movement information is realized.