CN110500127B - Dynamic treatment method for preventing non-uniform settlement of roof in roof cutting roadway without coal pillars - Google Patents
Dynamic treatment method for preventing non-uniform settlement of roof in roof cutting roadway without coal pillars Download PDFInfo
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- CN110500127B CN110500127B CN201910652273.7A CN201910652273A CN110500127B CN 110500127 B CN110500127 B CN 110500127B CN 201910652273 A CN201910652273 A CN 201910652273A CN 110500127 B CN110500127 B CN 110500127B
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- 239000003245 coal Substances 0.000 title claims abstract description 85
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- 230000005641 tunneling Effects 0.000 claims abstract description 13
- 238000000605 extraction Methods 0.000 claims abstract description 8
- 238000007726 management method Methods 0.000 claims abstract description 3
- 239000007787 solid Substances 0.000 claims description 32
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- 229910000746 Structural steel Inorganic materials 0.000 claims description 3
- 238000004873 anchoring Methods 0.000 claims description 3
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- 230000005540 biological transmission Effects 0.000 abstract description 2
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- 238000005192 partition Methods 0.000 abstract 2
- 238000009412 basement excavation Methods 0.000 description 4
- 238000011084 recovery Methods 0.000 description 4
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- 239000011358 absorbing material Substances 0.000 description 1
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- E21C41/00—Methods of underground or surface mining; Layouts therefor
- E21C41/16—Methods of underground mining; Layouts therefor
- E21C41/18—Methods of underground mining; Layouts therefor for brown or hard coal
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- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
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Abstract
The invention relates to a dynamic management method for preventing and controlling non-uniform settlement of a roof in a roadway by roof cutting without coal pillars, wherein during the tunneling of the roadway, a first anchor rod cable system A1 and a second anchor rod cable system A2 are alternately arranged along the tunneling direction; the anchor rod cable parameters and the installation position of the anchor rod cable parameters are designed in a partition mode, the roof is reinforced in the partition mode in the initial stage, and the anchor rod cable systems in the two areas are mutually influenced and matched through the transmission effect of internal force, so that the stability control of the roof during tunneling is jointly realized. In addition, the anchor rods and the anchor cables are integrally arranged at the same time, so that the stress state of the shallow coal rock mass is favorably improved, the reinforcing strength of the shallow coal rock mass is improved, and the deformation and the damage of shallow surrounding rocks are limited. During the working face extraction period, the design of the parameters of the internal pulling anchor cable and the installation position of the internal pulling anchor cable is carried out on the top plate, and the uneven settlement control of the top plate is realized. Through time-sharing supporting measures during tunneling and mining, effective force of anchor cables installed in two time periods is transmitted and matched, and effective control over a top plate is achieved jointly.
Description
Technical Field
The invention relates to the field of coal mine roadway support, in particular to a dynamic treatment method for preventing non-uniform settlement of a roof of a non-pillar roof cutting roadway.
Background
Roof cutting and roadway forming are a novel coal-pillar-free mining mode, filling rock pillars in conventional gob-side entry retaining are omitted, artificial filling materials are not needed, roof pressure is only needed to be relieved and the roof is dropped, and coal-pillar-free mining can be achieved by utilizing mine pressure and the broken expansion characteristic of rock mass. In fact, due to the particularity of the coal pillar-free roof-cutting roadway-forming process, the asymmetry of the roof-cutting roadway-forming surrounding rock structure and stress distribution along the two sides of the central axis of the roadway is caused: in the aspect of a surrounding rock structure, one side of the surrounding rock structure is a damaged coal rock body which is subjected to collapse and compaction processes, and the other side of the surrounding rock structure is solid coal which keeps better integrity, wherein the mechanical properties of the coal rock body and the solid coal are obviously different; in the aspect of stress distribution, the roof cutting roadway is integrally positioned in the stress reduction area, but the roof close to the solid coal side and the solid coal side are both positioned in the concentrated stress area. The difference of the surrounding rock structure and the stress distribution on two sides along the central axis of the roadway can cause the difference of deformation and damage characteristics of the top plate, so that the non-uniform settlement of the roadway top plate is caused, namely the settlement of the top plate on the mining area side is far greater than that of the top plate on the coal side, and the top plate is seriously inclined towards the mining area side. When the roof is supported by adopting the traditional symmetrical anchor rod cable structure, the roof is seriously sunk to the side of a mining area, the area of the section of a roadway is seriously compressed, and ventilation and pedestrians are influenced.
Disclosure of Invention
The invention provides a treatment method for non-uniform settlement of a roof in a roof-cutting roadway without coal pillars in order to solve the problem of non-uniform settlement of the roof in the roof-cutting roadway without coal pillars.
The technical scheme adopted by the invention is as follows: a dynamic management method for preventing and controlling non-uniform settlement of a roof in a roadway without coal pillar roof cutting comprises the steps of adopting a time-sharing support measure, and alternately arranging a first anchor rod cable system and a second anchor rod cable system along the roadway excavation direction during excavation until the roadway excavation is finished; during the recovery, along with the propulsion of the working face, an internal pulling anchor cable truss beam system is arranged between the first anchor rod cable system and the second anchor rod cable system until the recovery of the working face is finished, and the method specifically comprises the following steps:
step one), arranging a first anchor rod cable system and a second anchor rod cable system along the direction of a roadway during tunneling;
step 1) arranging a first anchor rod system, comprising the following steps:
step 1.11), determining different anchor rod and cable combination schemes based on a theoretical calculation formula according to the conditions of the top and the bottom of the coal seam, the width of the roadway and the parameter models of the anchor rod and cable, so that the bearing capacity of the top plate after supporting is not lower than 0.5MPa, wherein the calculation formula is as follows:
wherein sigma is the bearing capacity of the top plate after supporting, Q is the pretightening force applied to the anchor rod or the anchor cable, and l0The effective length of the anchor rod or the anchor cable; alpha is anchor rod or anchor cable control angle, s0The distance between anchor rods or anchor cables;
the inner friction angle of the roof rock mass after supporting is adopted, and R is the effective radius of the roadway;
then, combining actual geological conditions, establishing a numerical calculation model, checking and calculating the stress state of the top plate under different anchor rod and cable combination conditions, and determining an anchor rod and cable combination scheme according to the stress state;
step 1.12) according to the determined anchor rod and cable combination scheme, from the center line of the roadway to the side of the solid coal side, sequentially naming the anchor rod and cable as Z1、Z2·····ZiTo the coal pillar side 4, anchor rods and cables are named as Z in sequence1＇、Z2＇·····Zi' i is the number of the anchor rods and cables on one side of the roadway, and the adjacent anchor rods or anchor cables are arranged at intervals of 600 mm-1200 mm;
step 1.13) determining the positions of an anchor rod and an anchor cable of the anchor rod cable, wherein the anchor rod cable Z is close to the side of the solid coal sideiMust be anchor cable, otherwise at Zi-2To Zi-11-2 anchor cables are arranged in the area, and the rest positions are anchor rod structures;
step 1.2) the roadway top plate is positioned in the same vertical plane, and an anchor rod or an anchor cable structure is driven into the top plate through a construction machine, wherein the anchor cable Z isiInclining towards the side of the solid coal side, and arranging other anchor rods or anchor cables to be vertical to the top plate;
step 1.3) connecting the anchor rods and the anchor cables through a belt-shaped connecting structure, and applying pretightening force to form a first anchor rod system A1;
step 2) arranging a second anchor rod system, comprising the following steps:
step 2.1) determining different anchor rod cable combinations according to the conditions of the top and the bottom of the coal seam, the width of the roadway and the parameter models of the anchor rod cables, so that the bearing capacity of the top plate after supporting is not lower than 0.5 MPa;
step 2.11) according to the determined anchor rod and cable combination scheme, from the center line of the roadway to the side of the solid coal side, the anchor rod and cable are named as Y in sequence1、Y2·····YiFrom 4 to the side of the coal pillar, anchor rods and cables are named as Y in sequence1＇、Y2＇·····Yi' i is the number of the anchor rods and cables on one side of the roadway, and the adjacent anchor rods or anchor cables are arranged at intervals of 600 mm-1200 mm;
step 2.12) determining the positions of an anchor rod and an anchor cable of the anchor rod cable, wherein the positions close to the coal pillar side and the solid coal side are Yi' and YiIs a anchor rod and an anchor cableIn the central region of the roadway, i.e. Y2To Y2"in the range of;
step 2.2) placing the roadway top plate in the same vertical plane, driving an anchor rod or an anchor cable structure into the top plate through a construction machine, inclining the anchor rod Yi to the side of the solid coal slope, and arranging the rest anchor rods or anchor cables to be vertical to the top plate;
step 2.3) connecting the anchor rod and the anchor cable through a belt-shaped connecting structure, and applying pretightening force to form a second anchor rod system;
step two), arranging an internal pulling anchor cable truss girder system between the first anchor rod cable system and the second anchor rod cable system during the recovery period;
step 1) additionally arranging at least 2 inner anchor cables to a roadway top plate in an end head area of a working face, wherein the inner anchor cables incline to the side of a solid coal wall, the span between adjacent anchor cables is more than or equal to 1500mm and less than or equal to 3000mm, and the distance between each inner anchor cable and the side of the coal pillar wall is more than or equal to 500mm and less than or equal to 1000 mm;
and 2) connecting the anchor cables on the surface of the top plate by using a truss structure on the surface of the top plate to form an internal pulling anchor cable truss system.
Further, the number i of anchor rods and cables of the first anchor rod and cable system is less than or equal to 4, and the number of anchor cables is less than or equal to 3; the angle alpha of the anchor cable Zi of the first anchor rod cable system inclining to the solid coal side is not less than 10 degrees and not more than 25 degrees.
Further, the anchor rod in the first anchor rod cable system is a full-thread steel high-strength anchor rod with the diameter of 20-22 mm, the length of 2400-2700 mm and the pre-tightening force of not less than 80 kN; the anchor cable is made of 1 multiplied by 7 structural steel stranded wires with the diameter of 17-22 mm, the length of 5300-6300 mm, and the pretightening force of not less than 120 kN.
Further, the number i of anchor rods and cables of the second anchor rod and cable system is less than or equal to 4, and the number of anchor cables is less than or equal to 3; anchor rod Y close to side of solid coal sideiThe inclination angle alpha is more than or equal to 10 degrees and less than or equal to 25 degrees towards the solid coal side.
Further, the anchor rod in the second anchor rod cable system is a full-thread steel high-strength anchor rod with the diameter of 20-22 mm, the length of 2400-2700 mm and the pre-tightening force of not less than 80 kN; the anchor cable is made of steel strands with the diameter of 17-22 mm, the length of the steel strands is 7300-8300 mm, and the pretightening force of the steel strands is not lower than 120 kN.
Furthermore, the thickness f of the belt-shaped connecting structure is more than or equal to 5mm and less than or equal to 10mm, the width e of the belt-shaped connecting structure is more than or equal to 200mm and less than or equal to 500mm, the length d is (2i-1) b +400mm, and b is the distance between anchor rods and cables; a round hole for the anchor rod cable to pass through is designed on the anchor rod cable, and the diameter c of the round hole is more than or equal to 25 and less than or equal to 30 mm.
Furthermore, the included angle beta between the inner pulling anchor cable of the inner pulling anchor cable truss girder structure and the vertical direction is not less than 50 degrees and not more than 80 degrees, the span between the adjacent inner pulling anchor cables is not less than 1500mm and not more than 3000mm, and the distance between the inner pulling anchor cable and the coal pillar side is not less than 500mm and not more than 1000 mm.
Furthermore, the inner pulling anchor cable of the inner pulling anchor cable truss girder structure is made of 1 multiplied by 19 strands of steel stranded wires with the diameter of 17-22 mm, and the pretightening force is not lower than 120 kN.
Further, the length M of the inner pulling anchor cable1、M2Determined according to the following formula:
C0is the cohesion of coal-rock junction, /)0The internal friction angle at the coal rock junction is shown; m is the thickness of the coal bed; supporting force of the Px bracket on the coal side; a is a side pressure coefficient; k is the stress concentration coefficient; gamma is the average volume weight of the rock stratum; h is the depth of the roadway from the ground surface; m is the distance between the anchor cable and the coal pillar side, and n is the distance between the inner pull anchor cables.
Furthermore, the truss structure consists of a base and a trapezoid-like pressure yielding device, the base is arranged close to the top plate of the roadway, the trapezoid-like pressure yielding device is arranged below the base, the trapezoid-like pressure yielding device is of a right-angle trapezoid structure, an anchor cable hole is formed in the direction perpendicular to the oblique edge of the trapezoid-like pressure yielding device, and the oblique anchor cable hole is formed in the base and corresponds to the oblique anchor cable hole; the base is of a plate structure, the length is s, the width is k, the thickness is r, s is (j-1) n +400mm, k is more than or equal to 350mm and less than or equal to 600mm, and r is more than or equal to 6mm and less than or equal to 15 mm; the diameter of the anchor cable hole is more than or equal to 25mm and less than or equal to 30 mm.
The invention has the beneficial effects that:
1. during the tunneling of the roadway, the anchor rod cable parameters and the installation positions of the anchor rod cable parameters are designed in a partitioning mode, the roof is reinforced in a partitioned initial stage, the A1 anchor rod cable system is used for reinforcing the roof area close to the side of the solid coal, the A2 anchor rod cable system is used for reinforcing the roof in the middle area of the roadway, and the anchor rod cable systems in the two areas are matched with each other through the transmission effect, the mutual influence and the mutual cooperation of the internal force, so that the roof stability control during the tunneling is realized together. In addition, the anchor rods and the anchor cables are integrally arranged at the same time, so that the stress state of the shallow coal rock mass is favorably improved, the reinforcing strength of the shallow coal rock mass is improved, and the deformation and the damage of shallow surrounding rocks are limited.
2. During the working face extraction period, the design of the parameters of the internal pulling anchor cable and the installation position of the internal pulling anchor cable is carried out on the top plate, and the uneven settlement control of the top plate is realized. The anchoring points of the internal pulling anchor cables are positioned on the top plate above the stable solid coal, but not on the top plate right above the roadway with lower stability, the anchoring points are firm and are not easy to fall off, and the top plate is effectively tensioned and suspended through the inclined tensioning force of the anchor cables; the lower truss girder structure has the functions of yielding and absorbing energy, and under the tensioning action of the anchor cable, the truss girder structure is prevented from being cracked and torn while the roof board is sufficiently protected, so that the roof board is effectively controlled from inclining and sinking. Through time-sharing supporting measures during tunneling and mining, effective force of anchor cables installed in two time periods is transmitted and matched, and effective control over a top plate is achieved jointly.
Drawings
Fig. 1-schematic view during tunnelling;
figure 2-top plan view of roof support during roadway driving;
FIG. 3-A1 Anchor rope System I-I section view;
4-A2 Anchor rope System II-II section view;
FIG. 5 is a schematic perspective view of roof support during roadway driving;
FIG. 6 is a schematic view of a ribbon bond configuration;
FIG. 7 is a cross-sectional view of the ribbon bond;
FIG. 8-schematic representation of the working face extraction period;
figure 9-top plan view of roof support during roadway extraction;
fig. 10-a 3 anchor cable system iii-iii in section;
FIG. 11 is a schematic perspective view of roof support during face extraction;
FIG. 12 is a schematic view of a truss structure;
FIG. 13-top view of the base;
1-roadway, 2-roof, 3-solid coal side, 4-coal pillar side, 5-belt connecting structure, 6-working face end region, 7, 8-anchor cable, 9-plate structure and 10-type trapezoid yielding device;
the method comprises the following steps of a-A1 system-A2 system spacing, b-anchor rod cable spacing, c-round hole aperture, d-strip structure length, e-strip structure width, f-strip structure thickness, i-A1 and A2 system anchor rod cable quantity, j-A3 system anchor rod cable quantity, k-truss beam base width, l-roadway width, m-anchor cable-coal pillar side distance, n-internal pulling anchor cable spacing, r-truss beam base thickness and s-truss beam base length.
Detailed Description
Example 1
As shown in fig. 1-5, step one) arranging a first anchor cable system a1 and a second anchor cable system a2 in the direction of the roadway during excavation, with a spacing a between the two systems;
as shown in fig. 1, 2 and 3, step 1) arranges the first bolting system a1 as follows: step 1.1) determining different anchor rod and cable combination schemes based on a theoretical calculation formula according to the conditions of the coal seam roof and floor 2, the roadway width l and the anchor rod and cable parameter model, so that the bearing capacity of the roof after supporting is not lower than 0.5MPa, and the calculation formula is as follows:
wherein sigma is the bearing capacity of the top plate after supporting, Q is the pretightening force applied to the anchor rod or the anchor cable, and l0The effective length of the anchor rod or the anchor cable; alpha is anchor rod or anchor cable control angle, s0The distance between anchor rods or anchor cables;
the inner friction angle of the roof rock mass after supporting is adopted, and R is the effective radius of the roadway;
establishing a numerical calculation model by combining actual geological conditions, checking and calculating the stress state of the top plate under different anchor rod and cable combination conditions, and determining an anchor rod and cable combination scheme according to the stress state;
step 1.11) from the center line of the roadway to the side 3 of the solid coal side, anchor rods and cables are named as Z in sequence1、Z2、Z3To the coal pillar side 4, anchor rods and cables are named as Z in sequence1＇、Z2＇、Z3' the number i of the anchor rods and the anchor cables on the single side of the roadway is 3, the total number of the anchor rods and the anchor cables is 6, the number of the anchor cables is 3, and the adjacent anchor rods or anchor cables are arranged at intervals of 600 mm-1200 mm (see fig. 3 and 4); the anchor rod is a full-thread steel high-strength anchor rod with the diameter of 20-22 mm, the length of 2400-2700 mm and the pre-tightening force of not less than 80 kN; the anchor cable is a1 × 7 structural steel stranded wire with the diameter of 17-22 mm, the length of 5300-6300 mm, and the pretightening force of not less than 120 kN;
step 1.12) determining the positions of anchor rods and anchor cables of anchor rods and cables, wherein the position Z3 close to the solid coal side 3 is an anchor cable, the positions Z1' and Z2 are anchor cables, supporting of a top plate in the range from the middle to the solid coal side 3 is strengthened, and the rest positions are anchor rod structures (see fig. 2 and 5);
step 1.2) the roadway top plate 2 is positioned in the same vertical plane, an anchor rod or anchor cable structure is driven into the top plate 2 through a construction machine, an anchor cable Z3 inclines towards the solid coal side 3, the inclination angle is not less than 10 degrees and not more than alpha and not more than 25 degrees, and the rest anchor rods or anchor cables are arranged perpendicular to the top plate 2 (see fig. 3);
step 1.3) connecting the anchor rods and the anchor cables through a belt-shaped connecting structure 5, and applying pretightening force to form a first anchor rod system A1; (see fig. 6 and 7); f is more than or equal to 5mm and less than or equal to 10mm in thickness, e is more than or equal to 200mm and less than or equal to 500mm in width, d is (2i-1) b +400mm in length, and b is the anchor rod cable spacing; a round hole for the anchor rod cable to pass through is designed on the anchor rod cable, and the diameter c of the round hole is more than or equal to 25 and less than or equal to 30 mm.
Step 2) arranging a second anchor rod system A2 at a position which is about 1600 mm-1200 mm away from the first anchor rod system A1 along the tunneling direction, and the steps are as follows: step 2.1) determining the number of anchor rods and cables and the installation positions of the anchor rods and the anchor cables by a theoretical calculation or numerical simulation method according to the conditions of the top and the bottom of the coal seam and the width l of the roadway;
step 2.11) naming the anchor rod cables, and from the center line of the roadway to the side 3 of the solid coal side, sequentially naming the anchor rod cables as Y1、Y2、Y3From 4 to the side of the coal pillar, anchor rods and cables are named as Y in sequence1＇、Y2＇、Y3' the number i of the rock bolt cables on the single side of the roadway is 3, and the rock bolt cables comprise 6 anchor rods and 2 anchor cables in total (see fig. 2, 4 and 5); the adjacent anchor rods or anchor cables are arranged at intervals of 600-1200 mm; the anchor rod is a full-thread steel high-strength anchor rod with the diameter of 20-22 mm, the length of 2400-2700 mm and the pre-tightening force of not less than 80 kN; the anchor cable is made of steel strands with the diameter of 17-22 mm, the length of the steel strands is 7300-8300 mm, and the pre-tightening force is not lower than 120 kN;
step 2.12) determining the positions of the anchor rods and the anchor cables of the anchor rods, wherein Y3 ' and Y3 at the positions close to the coal pillar side 4 and the solid coal side 3, Y1 and Y1 ' positioned in the middle area of the roadway are the anchor rods, Y2 and Y2 ' are the anchor cables, and supporting on the middle area of the top plate is enhanced (see fig. 2 and 5).
Step 2.2) the roadway top plate 2 is positioned in the same vertical plane, an anchor rod or an anchor cable structure is driven into the top plate through a construction machine, and the anchor rod Y3Inclining towards the solid coal side 3, wherein the inclination angle is more than or equal to 10 degrees and less than or equal to 25 degrees, and the rest anchor rods or anchor cables are arranged perpendicular to the top plate 2 (see figure 4);
step 2.3) connecting the anchor rods and the anchor cables through the belt-shaped connecting structures 5, and applying pretightening force to form a second anchor rod system A2;
8-12, step two) arranging an inner pull cable truss system A3 between the first anchor cable system A1 and the second anchor cable system A2 at the face end region 6 during recovery;
step 1) in a working face end area 6, additionally installing 2 inner pulling anchor cables 7 and 8, which can be 3 or 4, on a roadway top plate 2, wherein at least one inner pulling anchor cable is close to a coal pillar side 4, and one inner pulling anchor cable is close to a roadway central line; the internal pulling anchor cables 7 and 8 are towards the side of the solid coal side3, the inclination angle is more than or equal to 50 degrees and less than or equal to 80 degrees, the span between adjacent anchor cables is more than or equal to 1500mm and less than or equal to 3000mm, and the distance between the anchor cable and the coal pillar side 4 is more than or equal to 500mm and less than or equal to 1000mm (see the figure 11, the figure 12 and the figure 13); 1 multiplied by 19 strands of steel stranded wires with the diameter of 17-22 mm are selected as the inner-pulling anchor cables 7 and 8, and the pretightening force is not lower than 120 kN; length M of inner pull anchor cable 7, 81、M2Determined according to the following formula:
C0is the cohesion of coal-rock junction, /)0The internal friction angle at the coal rock junction is shown; m is the thickness of the coal bed; supporting force of the Px bracket on the coal side; a is a side pressure coefficient; k is the stress concentration coefficient; gamma is the average volume weight of the rock stratum; h is the depth of the roadway from the ground surface; m is the distance between the anchor cable and the coal pillar side, and n is the distance between the inner-pulling anchor cables;
step 2) connecting the anchor cables on the surface of the top plate 2 by using a truss structure on the surface of the top plate 2 to form an internal pulling anchor cable truss system A3; the truss structure is composed of a base 9 and a trapezoid-like yielding device 10, the base 9 is arranged close to a roadway top plate, the trapezoid-like yielding device 10 is arranged below the base 9, the trapezoid-like yielding device 10 is of a right-angle trapezoid structure, an anchor cable hole is formed in a direction perpendicular to the oblique edge of the trapezoid-like yielding device, and the trapezoid-like yielding device and the oblique anchor cable hole are arranged on the base 9 correspondingly (see fig. 12 and 13); the trapezoid-like yielding device 10 is made of an energy-absorbing material, the material is a synthetic elastic material with both flexibility and elasticity, and the material can be subjected to significant compression deformation through the close contact of internal molecules under the action of external force, so that the external force is converted into the internal force, and the purpose of absorbing energy is achieved; the pressure yielding device is connected with the base 9 through chemical or physical action; the base 9 is of a plate structure, the length is s, the width is k, the thickness is r, s is (2j-1) × n +400mm, k is more than or equal to 350mm and less than or equal to 600mm, and r is more than or equal to 6mm and less than or equal to 15 mm; c is more than or equal to 25mm and less than or equal to 30mm (see figures 12 and 13).
Claims (10)
1. A dynamic management method for preventing and treating non-uniform settlement of a roof of a coal-pillar-free roof cutting roadway is characterized in that a time-sharing support measure is adopted, and a first anchor rod cable system (A1) and a second anchor rod cable system (A2) are alternately arranged along the tunneling direction of the roadway during tunneling until the tunneling of the roadway is finished; arranging an inner pull anchor cable truss girder system (A3) between a first anchor cable system (A1) and a second anchor cable system (A2) along with the advancing of a working face during the extraction till the extraction of the working face is finished, and specifically comprising the following steps:
step one) arranging a first anchor cable system (A1) and a second anchor cable system (A2) along the roadway direction during tunneling;
step 1) arranging a first bolting system (a1), the steps being as follows:
step 1.11), determining different anchor rod and cable combination schemes based on a theoretical calculation formula according to the conditions of the top and the bottom of the coal seam, the width of the roadway and the parameter models of the anchor rod and cable, so that the bearing capacity of the top plate after supporting is not lower than 0.5MPa, wherein the calculation formula is as follows:
wherein sigma is the bearing capacity of the top plate after supporting, Q is the pretightening force applied to the anchor rod or the anchor cable, and l0The effective length of the anchor rod or the anchor cable; alpha is anchor rod or anchor cable control angle, s0The distance between anchor rods or anchor cables;
the inner friction angle of the roof rock mass after supporting is adopted, and R is the effective radius of the roadway;
then, combining actual geological conditions, establishing a numerical calculation model, checking and calculating the stress state of the top plate under different anchor rod and cable combination conditions, and determining an anchor rod and cable combination scheme according to the stress state;
step 1.12) according to the resultsThe fixed anchor rod cable combination scheme is characterized in that from the center line of a roadway to the side (3) of the solid coal side, the anchor rod cables are named as Z in sequence1、Z2·····ZiTo the coal pillar side (4), the anchor rod cable is named as Z in sequence1＇、Z2＇·····Zi' i is the number of the anchor rods and cables on one side of the roadway, and the adjacent anchor rods or anchor cables are arranged at intervals of 600 mm-1200 mm;
step 1.13) determining the positions of an anchor rod and an anchor cable of the anchor rod cable, wherein the anchor rod cable Z is close to the solid coal side (3)iMust be anchor cable, otherwise at Zi-2To Zi-11-2 anchor cables are arranged in the area, and the rest positions are anchor rod structures;
step 1.2) the roadway top plate (2) is positioned in the same vertical plane, and an anchor rod or an anchor cable structure is driven into the top plate (2) through a construction machine, wherein the anchor cable Z isiThe coal side (3) is inclined, and the other anchor rods or anchor cables are arranged perpendicular to the top plate (2);
step 1.3) connecting the anchor rods and the anchor cables through a belt-shaped connecting structure, and applying pretightening force to form a first anchor rod system (A1);
step 2) arranging a second bolting system (a2), the steps being as follows:
step 2.1) determining different anchor rod and cable combinations according to the conditions of the top and the bottom of the coal seam, the width of the roadway and the parameter models of optional supporting anchor rod and cable, so that the bearing capacity of the top plate after supporting is not lower than 0.5 MPa;
step 2.11) according to the determined anchor rod cable combination scheme, from the center line of the roadway to the solid coal side (3), the anchor rod cables are named as Y in sequence1、Y2·····YiFrom the side (4) of the coal pillar, anchor rods and cables are named as Y in sequence1＇、Y2＇·····Yi' i is the number of the anchor rods and cables on one side of the roadway, and the adjacent anchor rods or anchor cables are arranged at intervals of 600 mm-1200 mm;
step 2.12) determining the positions of an anchor rod and an anchor cable of the anchor rod cable, wherein the positions close to the coal pillar side (4) and the solid coal side (3) are Yi' and YiFor anchoring bolts, the anchorage cable being located in the central region of the roadway, i.e. Y2To Y2"in the range of;
step 2.2) lanewayThe top plate (2) is positioned in the same vertical plane, an anchor rod or an anchor cable structure is driven into the top plate (2) through a construction machine, and the anchor rod YiThe coal side (3) is inclined, and the other anchor rods or anchor cables are arranged perpendicular to the top plate (2);
step 2.3) connecting the anchor rods and the anchor cables through a belt-shaped connecting structure, and applying pretightening force to form a second anchor rod system (A2);
step two) arranging an inner pull anchor cable truss system (A3) between the first anchor cable system (a1) and the second anchor cable system (a2) during extraction;
step 1) additionally arranging at least 2 inner pulling anchor cables (7) and (8) on a roadway top plate (2) in a working face end head area (6), wherein the inner pulling anchor cables (7) and (8) incline to an entity coal side (3), the span between adjacent anchor cables is more than or equal to 1500mm and less than or equal to 3000mm, and the distance between the anchor cables and a coal pillar side (4) is more than or equal to 500mm and less than or equal to 1000 mm;
and 2) connecting the anchor cables on the surface of the top plate by using a truss structure on the surface of the top plate to form an internal pulling anchor cable truss system (A3).
2. The dynamic governance method for preventing non-uniform settlement of the roof of the coal-pillar-free roof-cutting roadway according to claim 1, wherein the number i of anchor rods of the first anchor rod cable system (A1) is less than or equal to 4 and the number of anchor cables is less than or equal to 3; first anchor rod cable system (A1) anchor cable ZiThe angle alpha inclined to the solid coal side (3) is more than or equal to 10 degrees and less than or equal to 25 degrees.
3. The dynamic governing method for preventing and treating non-uniform settlement of roof plates in coal-pillar-free roof cutting and roadway forming according to claim 1, wherein full-thread steel high-strength anchor rods with the diameter of 20-22 mm and the length of 2400-2700 mm are selected as anchor rods in the first anchor rod cable system (A1), and the pre-tightening force is not lower than 80 kN; the anchor cable is made of 1 multiplied by 7 structural steel stranded wires with the diameter of 17-22 mm, the length of 5300-6300 mm, and the pretightening force of not less than 120 kN.
4. The dynamic governing method for preventing and treating non-uniform settlement of roof in coal-pillar-free roof-cutting roadway according to claim 1, wherein the number i of anchor rods and cables of the second anchor rod and cable system (A2) is less than or equal to 4 and the number of anchor cables is less than or equal to 4Less than or equal to 3; an anchor rod Y close to the solid coal side (3)iThe angle of inclination to the solid coal side (3) is more than or equal to 10 degrees and less than or equal to 25 degrees.
5. The dynamic governing method for preventing and treating non-uniform settlement of the roof of the coal-pillar-free roof-cutting roadway according to claim 1, wherein the anchor rod in the second anchor rod cable system (A2) is a full-thread steel high-strength anchor rod with a diameter of 20-22 mm, a length of 2400-2700 mm and a pretightening force of not less than 80 kN; the anchor cable is made of steel strands with the diameter of 17-22 mm, the length of the steel strands is 7300-8300 mm, and the pretightening force of the steel strands is not lower than 120 kN.
6. The dynamic governance method for preventing and treating non-uniform settlement of the roof of the coal-pillar-free roof-cutting roadway according to claim 1, wherein the thickness f of the belt-shaped connecting structure is 5mm or more and 10mm or less, the width e of the belt-shaped connecting structure is 200mm or more and 500mm or less, the length d is (2i-1) b +400mm, and b is the distance between anchor rods and cables; a round hole for the anchor rod cable to pass through is designed on the anchor rod cable, and the diameter c of the round hole is more than or equal to 25 and less than or equal to 30 mm.
7. The dynamic governance method for preventing and treating non-uniform settlement of the coal-pillar-free roof-cutting roadway roof as claimed in claim 1, wherein the included angle between the inner pulling anchor cables (7) and (8) of the inner pulling anchor cable truss structure (A3) and the vertical direction is 50 degrees or more and beta or less and 80 degrees or less, the span between the adjacent inner pulling anchor cables (7) and (8) is 1500mm or more and n or more and 3000mm or less, and the distance between the inner pulling anchor cable (7) and the coal pillar side (4) is 500mm or more and m or more and 1000mm or less.
8. The dynamic treatment method for preventing and treating non-uniform settlement of the roof of the coal-pillar-free roof-cutting roadway, as claimed in claim 1, wherein the inner-pulling anchor cables (7) and (8) of the inner-pulling anchor cable truss structure (A3) are 1 x 19 strands of steel strands with the diameter of 17-22 mm, and the pre-tightening force is not lower than 120 kN.
9. The dynamic governing method for preventing and controlling non-uniform settlement of roof in coal-pillar-free roof-cutting roadway according to claim 1, wherein the lengths M of the anchor cables (7, 8) are M1、M2Determined according to the following formula:
C0is the cohesion of coal-rock junction, /)0The internal friction angle at the coal rock junction is shown; m is the thickness of the coal bed; supporting force of the Px bracket on the coal side; a is a side pressure coefficient; k is the stress concentration coefficient; gamma is the average volume weight of the rock stratum; h is the depth of the roadway from the ground surface; m is the distance between the anchor cable and the coal pillar side, and n is the distance between the inner pull anchor cables.
10. The dynamic governance method for preventing and treating non-uniform settlement of the top plate of the coal-pillar-free roof-cutting roadway according to claim 1, wherein the truss structure is composed of a base (9) and a trapezoid-like yielding device (10), the base (9) is arranged in close contact with the top plate of the roadway, the trapezoid-like yielding device (10) is arranged below the base (9), the trapezoid-like yielding device (10) is of a right-angle trapezoid structure, an anchor cable hole is formed in a direction perpendicular to the oblique edge of the trapezoid-like yielding device, and the trapezoid-like yielding device corresponds to the base (9) and is provided with an oblique anchor cable hole; the base (9) is of a plate structure, the length is s, the width is k, the thickness is r, s is (j-1) n +400mm, k is more than or equal to 350mm and less than or equal to 600mm, and r is more than or equal to 6mm and less than or equal to 15 mm; the diameter of the anchor cable hole is more than or equal to 25mm and less than or equal to 30 mm.
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Application publication date: 20191126 Assignee: Shandong Zeming Energy Technology Co.,Ltd. Assignor: SHANDONG University OF SCIENCE AND TECHNOLOGY Contract record no.: X2023370010027 Denomination of invention: A Dynamic Treatment Method for Preventing and Controlling Uneven Roof Subsidence in Coal Pillar Free Roof Cutting Roadway Granted publication date: 20201215 License type: Common License Record date: 20230309 |