CN114352285B - Construction method of large-section reverse well construction chamber - Google Patents
Construction method of large-section reverse well construction chamber Download PDFInfo
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- CN114352285B CN114352285B CN202111441238.4A CN202111441238A CN114352285B CN 114352285 B CN114352285 B CN 114352285B CN 202111441238 A CN202111441238 A CN 202111441238A CN 114352285 B CN114352285 B CN 114352285B
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- 238000010276 construction Methods 0.000 title claims abstract description 152
- 230000005641 tunneling Effects 0.000 claims abstract description 44
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- 238000009412 basement excavation Methods 0.000 claims abstract description 22
- 238000013461 design Methods 0.000 claims abstract description 7
- 229910000831 Steel Inorganic materials 0.000 claims description 25
- 239000010959 steel Substances 0.000 claims description 25
- 239000011435 rock Substances 0.000 abstract description 69
- 238000006073 displacement reaction Methods 0.000 abstract description 42
- 230000006378 damage Effects 0.000 description 22
- 239000003245 coal Substances 0.000 description 15
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- 238000009826 distribution Methods 0.000 description 11
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- 238000004458 analytical method Methods 0.000 description 4
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- 238000004519 manufacturing process Methods 0.000 description 4
- 239000004568 cement Substances 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- 238000004873 anchoring Methods 0.000 description 1
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- 238000005422 blasting Methods 0.000 description 1
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- 238000012938 design process Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
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Abstract
The invention discloses a construction method of a large-section reverse well construction chamber, which comprises the following steps: determining an auxiliary roadway construction point; and (B) step (B): completing an auxiliary roadway by tunneling construction; step C: tunneling downwards at a construction point of the large-section chamber according to an arch radian preset at the top of the large-section chamber to be excavated, and supporting after construction is completed to obtain a conventional-section chamber; step D: continuing tunneling according to the preset arch shape and size of the large-section chamber to be excavated; supporting after construction is completed; step E: dividing the side wall part of the large-section chamber to be excavated into a plurality of construction layers for tunneling downwards in a layered manner according to the design size of the large-section chamber to be excavated, supporting after each layer of excavation is completed, tunneling the next layer after the supporting is completed, and completing the construction of the large-section chamber after the last layer of supporting is completed. The invention solves the problems of serious deformation of the surrounding rock of the large-section chamber for the reverse well construction, poor stability of the roof strata, large vertical displacement of the roof surrounding rock in the service process and the like.
Description
Technical Field
The invention relates to the technical field of large-section chamber construction. In particular to a construction method of a large-section reverse well construction chamber.
Background
At present, as the diameter of a well reversing project is continuously enlarged, well reversing drill equipment also tends to be large-sized. Therefore, the requirements for the large-section construction chamber are increasingly greater whether the construction space of the shaft or the installation space of equipment is available. However, partial large-section chamber roof strata are weak strata, the overall strength is low, under the action of ground stress, the rock is easily influenced by excavation disturbance, and cracks in the rock body develop, so that roof surrounding rocks are broken; moreover, the large-section chamber has large excavation space, surrounding rock is greatly disturbed, and roof strata are positioned in a plastic region formed by vertical shaft excavation, so that the vertical displacement of the roof of the large-section chamber is far greater than that of a conventional section chamber. At present, large-section construction and support are difficult points of mine development tunneling all the time, and when a blasting tunneling construction method is used, the efficiency is low, the design requirement on the roadway support is high, and particularly when a roof stratum of a large-section chamber is unstable, the construction difficulty is high, and the roof surrounding rock of the large-section chamber is severely deformed and damaged in the service process. The novel method for searching the construction of the large-section chamber is significant in order to better control the stability of the surrounding rock of the large-section chamber.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to provide a construction method of a large-section reverse well construction chamber, and the problems that the surrounding rock of the large-section chamber for the current reverse well construction is serious in deformation, the rock stratum stability of a roof is poor, the vertical displacement of the surrounding rock of the roof is large in the service process and the like are solved by adopting a construction process of excavating and supporting in a divided manner.
In order to solve the technical problems, the invention provides the following technical scheme:
the construction method of the large-section reverse well construction chamber comprises the following steps:
Step A: determining an auxiliary roadway construction point in one roadway adjacent to the large-section chamber to be excavated according to the preset position of the large-section chamber to be excavated;
And (B) step (B): at the auxiliary roadway construction point, tunneling upwards along a preset bottom plate at the bottom of the large-section chamber to be excavated, and changing the tunneling direction when tunneling to the point that the top point of the large-section chamber to be excavated is on the same horizontal line: tunneling construction is conducted to the top position of the large-section chamber to be excavated along the horizontal direction; supporting after construction is completed to obtain an auxiliary roadway;
step C: taking the auxiliary roadway at the vertex of the large-section chamber to be excavated as a construction point of the large-section chamber; tunneling downwards at the construction point of the large-section chamber according to an arch radian preset at the top of the large-section chamber to be excavated, and supporting after construction is completed to obtain a conventional section chamber; the width of the conventional section chamber is smaller than that of the large section chamber to be excavated, and the height of the conventional section chamber is smaller than or equal to the arch height of the large section chamber to be excavated;
Step D: continuing tunneling according to the preset arch shape and size of the large-section chamber to be excavated, wherein a tunneling area comprises an area from two sides of the conventional section chamber to the preset top and the edge between the two sides of the large-section chamber to be excavated, and the lower boundary of the tunneling area and the bottom of the conventional section chamber are on the same horizontal plane; supporting after construction is completed;
Step E: dividing two sides of the large-section chamber to be excavated into two or more construction layers from top to bottom according to the design size of the large-section chamber to be excavated, tunneling downwards in layers, supporting after each layer of excavation is completed, tunneling the next layer after the support is completed, and completing the construction of the large-section chamber after the last layer of support is completed.
In the construction method of the large-section reverse well construction chamber, in the step C, the width of the conventional section chamber is equal to 1/2 of the width of the large-section chamber to be excavated; the height of the conventional section chamber is equal to the arch height of the large section chamber to be excavated.
In the step E, dividing the two sides of the large-section chamber to be excavated into 3 construction layers of a first step, a second step and a third step, and tunneling downwards; after the first step tunneling is completed, tunneling is continued to the auxiliary roadway, so that the first step is communicated with the auxiliary roadway, and slag soil generated in the construction process is conveniently transported out of the auxiliary roadway.
In the construction method of the large-section reverse well construction chamber, in the step C, when the conventional section chamber is supported, the top and the two sides of the conventional section chamber are supported by using round steel anchors with phi 16mm multiplied by 2000mm, and the interval row spacing of the round steel anchors is 1100mm multiplied by 1000mm.
In the construction method of the large-section reverse well construction chamber, in the step C, the top of the conventional section chamber is reinforced and supported by using anchor cables with phi 21.6mm multiplied by 6500mm, and the interval between the anchor cables is 2000mm; the anchor cables and the round steel anchor rods are arranged in staggered mode.
According to the construction method of the large-section reverse well construction chamber, when the large-section chamber is supported, the top and two sides of the large-section chamber are supported by adopting the anchor rods, the row spacing of the anchor rods at the top of the large-section chamber is 1000mm multiplied by 1000mm, and two adjacent anchor rods are connected by adopting the steel bar ladder beams welded by phi 14mm round steel; the row spacing of the anchor rods of the two sides of the large-section chamber is 800mm multiplied by 1000mm, and the anchor rods are perpendicular to the two sides of the large-section chamber.
According to the construction method of the large-section reverse well construction chamber, the top of the large-section chamber is reinforced and supported by adopting the anchor cables with phi 21.6mm multiplied by 8000mm, and the distance between the anchor cables is 2000mm.
According to the construction method of the large-section reverse well construction chamber, the roof of the large-section chamber and the two sides of the large-section chamber are both phi 20mm multiplied by 2500mm left-handed screw steel anchors.
According to the construction method of the large-section reverse well construction chamber, when the conventional section chamber is supported, the top and the two sides of the conventional section chamber are supported by using round steel anchor rods with phi 16mm multiplied by 2000mm, and the interval of the round steel anchor rods is 1100mm multiplied by 1000mm;
In the step C, the top of the conventional section chamber is reinforced and supported by using anchor cables with phi 21.6mm×6500mm, and the interval between the anchor cables is 2000mm; the anchor cables and the round steel anchor rods are arranged in staggered mode;
When the large-section chamber is supported, the top and two sides of the large-section chamber are supported by adopting an anchor rod, the row spacing between the anchor rods at the top of the large-section chamber is 1000mm multiplied by 1000mm, and two adjacent anchor rods are connected by adopting a steel bar ladder beam welded by phi 14mm round steel; the row spacing of the anchor rods of the two sides of the large-section chamber is 800mm multiplied by 1000mm, and the anchor rods are vertical to the two sides of the large-section chamber;
the top of the large-section chamber is reinforced and supported by anchor cables with phi 21.6mm multiplied by 8000mm, and the distance between the anchor cables is 2000mm;
The roof bolts used at the top of the large-section chamber and the two sides of the large-section chamber are all left-handed screw steel bolts with phi of 20mm multiplied by 2500 mm.
In the construction method of the large-section reverse well construction chamber, in the step B, in the process of upwards tunneling of the auxiliary roadway, the tunneling direction is adjusted according to the target position of the large-section chamber to be excavated.
The technical scheme of the invention has the following beneficial technical effects:
(1) The invention provides a construction method of a large-section reverse well construction chamber, which adopts a construction process of excavating and supporting in a divided manner, and strengthens and supports the top of the large-section chamber, thereby solving the problems of serious deformation of surrounding rocks of the large-section chamber for reverse well construction, poor stability of roof strata, large vertical displacement of the surrounding rocks of the roof in the service process and the like.
(2) When the large-section chamber is constructed, the tunnel is tunneled downwards from the top of the large-section chamber through the constructed auxiliary tunnel, the tunnel is tunneled while supported, the top of the large-section chamber is tunneled twice, a conventional section chamber is firstly constructed downwards from the top, and the support is carried out, so that the disturbance to a weak rock stratum with lower roof strength when the large-section chamber is constructed is greatly reduced; and then constructing the residual part of the arch of the top of the large-section chamber according to the shape and the size of the arch of the top of the large-section chamber, and supporting the residual part, thereby effectively preventing surrounding rock deformation caused by overlarge chamber cavity wall range. According to the invention, the two sides of the large-section chamber are tunneled in a layered manner, and the tunnelling construction of the next layer is performed after the tunnelling support of the coal seam is completed, so that the strength and stability of the support of the large-section chamber are ensured.
(3) According to the invention, through the construction auxiliary roadway, on one hand, slag soil generated in the construction process of the large-section chamber is conveniently transported out, and on the other hand, the construction of the large-section chamber can be realized from top to bottom, so that the disturbance of the construction tunneling to the rock stratum at the top of the large-section chamber is effectively reduced, the damage to the rock stratum at the top is reduced, the stability of the top plate of the large-section chamber is ensured, and the vertical displacement of the top plate of the large-section chamber is reduced. In addition, when the tunneling construction of the auxiliary roadway is started, the existing roadway adjacent to the large-section chamber can be selected as a starting point for tunneling, the tunneling direction can be adjusted according to the target position of the large-section chamber to be excavated in the tunneling construction process, the engineering quantity is saved, and the construction efficiency is improved.
Drawings
FIG. 1a is a plan view of a coal blind return vertical tie roadway in an embodiment of the invention;
FIG. 1b is a cross-sectional view of a coal blind return vertical shaft communication roadway in an embodiment of the invention;
FIG. 2 is a schematic view of a three-dimensional model of a large section and a conventional section in an embodiment of the present invention;
FIG. 3 is a graph of simulation results of vertical displacement of a large-section chamber surrounding rock when a conventional construction method is adopted in the embodiment of the invention;
FIG. 4 is a graph of simulation results of vertical displacement of a conventional section chamber surrounding rock when a conventional construction method is adopted in the embodiment of the invention;
FIG. 5 is a graph of simulation results of horizontal displacement of a large-section chamber surrounding rock when a conventional construction method is adopted in the embodiment of the invention;
FIG. 6 is a graph of the results of simulation of horizontal displacement of a conventional section chamber surrounding rock when a conventional construction method is adopted in the embodiment of the invention;
FIG. 7 illustrates a large section chamber plastic area layout when a conventional construction method is used in the embodiment of the invention;
FIG. 8 illustrates a conventional section chamber plastic area layout when a conventional construction method is used in the embodiment of the invention;
FIG. 9 is a graph showing the vertical stress distribution of a large-section chamber using a conventional construction method in the embodiment of the present invention;
FIG. 10 is a graph showing the vertical stress distribution of a conventional section chamber using a conventional construction method in the embodiment of the present invention;
FIG. 11 is a schematic view of a supporting scheme of a large section chamber in an embodiment of the invention;
FIG. 12 is a schematic view of a conventional section chamber in accordance with an embodiment of the present invention;
FIG. 13 is a schematic diagram of a large section chamber and conventional section chamber support scheme in accordance with an embodiment of the present invention;
FIG. 14 is a graph showing the results of simulation of vertical displacement of a large-section chamber surrounding rock when the construction method of the present invention is adopted in the embodiment of the present invention;
FIG. 15 is a graph of the results of simulation of vertical displacement of a conventional section chamber surrounding rock using the construction method of the present invention in the embodiment of the present invention;
FIG. 16 is a graph of simulated results of horizontal displacement of a large section chamber surrounding rock using the construction method of the present invention in the embodiment of the present invention;
FIG. 17 is a graph of the results of simulation of horizontal displacement of a conventional section chamber surrounding rock when the construction method of the present invention is adopted in the embodiment of the present invention;
FIG. 18 is a schematic diagram of a large section chamber plastic area layout when the construction method of the present invention is employed in the embodiment of the present invention;
FIG. 19 shows a conventional section chamber plastic section layout when the construction method of the present invention is used in the embodiment of the present invention.
The reference numerals in the drawings are as follows: 1-a conventional section chamber; 2-tunneling areas; 3-a first step; 4-a second step; 5-a third step; 6-coal return air main roadway (3-1); 7-coal hidden return air vertical shaft connecting roadways (3-1); 8-dark return air vertical shafts; 9-coal total return airway (3-1); 10-return air vertical shafts; 11-main major roadway connecting roadway; 12-phi 21.6mm by 8000mm anchor cable; 13-phi 20mm x 2500mm left-handed screw steel anchor rod; 14-phi 20mm x 2500mm left-handed screw steel anchor rod; 15-phi 16mm multiplied by 2000mm round steel anchor rod; 16-phi 21.6mm×6500mm anchor cable; 17-large section chamber.
Detailed Description
In the embodiment, the construction method is tested by taking a construction chamber of a large-section reverse well of a deepening section of a secondary horizontal return air vertical shaft of an XXX mine as a construction test point; in the embodiment, the surrounding rock destruction mechanism of the large-section chamber is simulated and analyzed by software, then the construction is performed by adopting the method of the embodiment, and the construction effect is simulated and analyzed by software after the construction is completed.
1. Engineering overview
The construction chamber of the large-section reverse well of the deepening section of the vertical well of the XXX mine is positioned at the intersection of the vertical well and a roadway, the section of the roadway is large, the occurrence state is complex, the number of times of excavation disturbance is large and strong, the design section is large, the structure is complex, the service life is required to be long, deformation damage of the chamber seriously affects up-and-down transportation, pedestrians and ventilation of a mine, and the safety, high yield and high-efficiency production of the coal mine are restricted.
The upper part of the deepening section of the XXX ore secondary horizontal return air vertical shaft is a 3-1 coal return air connecting roadway, the lower part is a 5-1 coal total return air roadway, the designed depth elevation is 1191.2m, the designed pit shaft landing elevation is 1113m, the designed total length is 78.2m, the tunneling section is a circle with the diameter of 6m, and the full-section primary reverse well tunneling is realized. The reverse well construction chamber is in a straight wall semicircular arch shape, the height of the large-section chamber is 7m, the width of the large-section chamber is 7m, the arch height is 3.5m, and the roadway cross-section area is about 43.73m 2; the conventional section chamber is 2.8m high and 3.5m wide, wherein the camber is 1.75m and the chamber cross-sectional area is about 8.48m 2. The roof stratum of the reverse well construction chamber is mainly sandy mudstone, and has low overall strength, poor stability, easy falling and easy breaking. The arrangement schematic diagram of the two horizontal return air vertical shaft deepening section reverse well construction chamber is shown in figure 1.
Analysis of failure mechanism of surrounding rock of large-section chamber of XXX ore
According to the embodiment, the distribution characteristics of the displacement field, the stress field and the damage field in the process of excavating the reverse well construction chamber are simulated and analyzed through FLAC 3D simulation software, and the deformation damage mechanism of surrounding rock of the large-section chamber of the XXX ore is revealed.
2.1 Numerical model establishment and simulation scheme
And (3) establishing a three-dimensional numerical calculation model according to the actual geological conditions of the XXX ore, as shown in figure 2. The X axis is the tunneling direction X=100deg.M of the reverse well construction chamber, the chamber is a straight wall semicircle arch, the lengths of the large section and the conventional section chamber are 40m and 25m respectively, and the joint of the large section and the conventional section is 5m; the Y axis is the coal seam inclination direction Y=100deg.M; the vertical direction of the Z axis is upwards Z=100deg.m, the simulated return air vertical shaft is 78.2m, the bottom plate is 19.42m, and the three-dimensional units are divided into 4685030 three-dimensional units and 797468 nodes. Model level and bottom boundary define 0. The load of 27.8MPa applied to the top of the model represents the overburden pressure, horizontal stress is applied to the X and Y directions of the model, and the side pressure coefficient is 1.3.
The coal rock mass is defined as a Mohr-coulomb model, and the physical and mechanical parameters of the coal rock mass required in the numerical simulation are shown in Table 1. The simulation program according to the actual construction process is as follows: initial stress calculation balance, conventional section chamber excavation, large section chamber layered excavation and return air vertical shaft excavation.
Table 1 physical and mechanical parameters of coal rock mass
2.2 Analysis of simulation results
Vertical displacement and horizontal displacement distribution cloud patterns of the reverse well construction chamber are shown in fig. 3, 4 and 5 and 6 respectively.
1) Vertical displacement distribution characteristics: as can be seen from fig. 3 and 4, the vertical displacement of the large-section and conventional-section chambers is symmetrically distributed, and the maximum sinking amount occurs at the vertical center line of the chamber top plate and is 1450mm and 505mm respectively, wherein the vertical displacement of the large-section chamber is 2.8 times that of the conventional-section chamber. The vertical displacement distribution characteristics of the reverse well construction chamber are closely related to the size of the vertical displacement distribution characteristics, the space formed in the large-section chamber digging process is larger, and further, the disturbance on surrounding rock mass is larger, so that the vertical displacement of the top plate of the large-section chamber is far larger than that of a conventional section chamber.
2) Horizontal displacement profile features. From fig. 5 and fig. 6, it can be seen that the horizontal displacement of the top plate and the two sides of the reverse well construction chamber from shallow to deep is gradually reduced, and the horizontal displacement of the top plate is symmetrically distributed along the vertical center line of the roadway and is in an extrusion state. The maximum horizontal displacement of the large-section and conventional-section chambers occurs at a distance from the chamber top plate of 189mm and 23mm respectively. The reason for this phenomenon is that the roof strata lithology and the vertical shaft excavation are superposed, the roof is a weak rock stratum, the strength is low, the vertical shaft excavation is carried out, the roof strata is disturbed, cracks develop, the rock mass is more broken, and the vertical shaft excavation space provides a horizontal movement space for the movement of the roof strata. As does the horizontal displacement of conventional section chambers, large section chambers provide horizontal movement space for them. Therefore, in the support design process, the adaptability of the chamber roof to horizontal movement is particularly required to be improved, and the roof is prevented from being damaged by extrusion deformation.
The distribution of the surrounding rock breaking field and the vertical stress field of the reverse well construction chamber is shown in fig. 7 to 10. As can be seen from the figures:
1) Plastic region distribution characteristics. As can be seen from fig. 7 and 8, the surrounding rock of the reverse well construction chamber is in a large-range shearing damage state, wherein the damage depth of the top plate of the large-section chamber is about 24m, and the damage depth of two sides is 13.5m; the damage depth of the top plate of the conventional section chamber is about 7.3m, the damage depth of two sides is 4.5m, part of the chamber is in tensile damage, the damage depth of the top is large, and the reinforced support control of the top is needed.
2) Vertical stress distribution features. As can be seen from fig. 9 and 10, the bottom plate and the two sides of the shallow coal body of the inverted well construction chamber are in a stress release state, and the average stress is about 1MPa, which indicates that serious fracture damage has occurred to the surrounding shallow surrounding rock of the chamber; for a large-section chamber, the stress gradually increases from the surface of the chamber side, and reaches peak stress at a position 14m away from the surface of the lane side, wherein the peak stress is 35MPa, and the stress concentration coefficient is 1.06; for a conventional section chamber, the stress also shows a gradually increasing trend, the peak stress is reached at the position 9m away from the roadway wall surface, the peak stress is 40.6MPa, the stress concentration coefficient is 1.23, and in the support design, the plastic damage range of the shallow coal body needs to be controlled so as to ensure normal ventilation, pedestrians and transportation.
3. Principle and technology for controlling surrounding rock of reverse well construction chamber
3.1 Chamber surrounding rock control principle
And (3) analyzing the deformation and damage process of the surrounding rock of the XXX mine reverse well construction chamber by combining the actual geological production conditions and the deformation and damage characteristics of the surrounding rock of the large-section chamber, wherein the deformation and damage process is as follows: ① The roof stratum of the mine anti-well construction chamber is a weak stratum, the strength is low, the roof stratum is greatly influenced by disturbance, so that the roof is obviously sunk and deformed, the vertical shaft excavates and the dimension of the chamber are changed, a moving space is provided for horizontal movement of the roof stratum of the chamber, the top of the chamber is obviously and horizontally displaced, and the chamber is extruded towards the vertical central line of the chamber. ② The large-section of the inverted well construction chamber has larger size, and the space formed in the excavation process is large, so that the vertical displacement of the top plate is far larger than that of the conventional section chamber; the reverse construction of the vertical shaft provides sufficient space for horizontal movement of the roof strata of the large-section chamber, so that the horizontal displacement of the vertical shaft is larger than that of the conventional section chamber.
Based on the theoretical analysis and numerical simulation results, the method is a key for guaranteeing the stability of the surrounding rock for the reverse well construction preparation in order to guarantee the safe and stable service of the reverse well construction chamber of the two-horizontal return air vertical deep section during the production service period, reducing disturbance to the roof rock stratum during construction, strengthening support to the roof, controlling the sinking amount and adapting to the horizontal extrusion deformation of the roof.
3.2 Control technique for surrounding rock of reverse well construction chamber
In order to better control the stability of surrounding rock of the large-section chamber, the large-section reverse well construction chamber is excavated and supported in a plurality of times, the conventional section chamber is formed at one time, and the on-site implementation process comprises the following steps: conventional section chamber excavation, conventional section chamber support, large section chamber excavation 1 layer, large section chamber support 1 layer, large section chamber excavation 2 layer, large section chamber support 2 layer, large section chamber excavation 3 layer, large section chamber support 3 layer. The method specifically comprises the following steps:
Step A: determining an auxiliary roadway construction point in one roadway adjacent to the large-section chamber to be excavated according to the preset position of the large-section chamber to be excavated;
and (B) step (B): at the auxiliary roadway construction point, tunneling upwards along a preset bottom plate at the bottom of the large-section chamber to be excavated, and changing tunneling direction when tunneling to the point that the top point of the large-section chamber to be excavated is on the same horizontal line: tunneling construction is conducted to the top position of the large-section chamber to be excavated along the horizontal direction; supporting after construction is completed to obtain an auxiliary roadway;
step C: taking the auxiliary roadway at the vertex of the large-section chamber to be excavated as a construction point of the large-section chamber; tunneling downwards at the construction point of the large-section chamber according to an arch radian preset at the top of the large-section chamber to be excavated, and supporting after construction is completed to obtain a conventional section chamber 1; the width of the conventional section chamber 1 is equal to 1/2 of the width of the large section chamber to be excavated, and the height of the conventional section chamber 1 is smaller than the arch height of the large section chamber to be excavated;
step D: continuing tunneling according to the preset arch shape and size of the large-section chamber to be excavated, wherein a tunneling area 2 comprises areas from two sides of the conventional-section chamber to the preset top and the edges between the two sides of the large-section chamber to be excavated, and the lower boundary of the tunneling area 2 and the bottom of the conventional-section chamber are on the same horizontal plane; supporting after construction is completed;
Step E: dividing the side wall part of the large-section chamber to be excavated into a first step 3, a second step 4 and a third step 5 according to the design size of the large-section chamber to be excavated, tunneling downwards in layers (as shown in figure 11), supporting after each layer of excavation is completed, tunneling the next layer after the supporting is completed, and completing the construction of the large-section chamber after the last layer of support is completed.
Based on the geological conditions of the mine production and the deformation and destruction rules of surrounding rocks of the reverse well construction chamber, different supporting schemes are adopted for different section sections of the reverse well construction chamber, and the reinforced supporting of the top plate of the chamber is emphasized. The specific parameters are as follows: all use phi 20mm 2500mm left-handed screw steel stock on the wall of big section chamber top, the row distance is 1000mm between roof stock, and every row is arranged 11 stock, and the stock adopts phi 14mm round steel to weld steel bar ladder roof beam to connect, adopts the anchor rope to carry out the reinforcement to the roof and strut, uses phi 21.6mm 8000mm anchor rope, and the interval is 2000mm. The row spacing between the two anchor rods is 800mm multiplied by 1000mm, 4 anchor rods in each row are vertically arranged on two sides (see figure 11).
Round steel anchor rods with phi 16mm multiplied by 2000mm are used for the top wall of the conventional section chamber of the XXX ore, and the interval is 1100mm multiplied by 1000mm; the top of the chamber is reinforced and supported by anchor cables with phi 21.6mm multiplied by 6500mm, the row spacing is 2000mm, and the anchor cables are arranged in staggered manner (see figure 12).
3.3 Analysis of numerical simulation results for supporting solutions
The anchor rod (cable) support simulation is carried out according to the construction scheme, and an XXX mine reverse well construction chamber anchor rod (cable) support simulation diagram is shown in fig. 13. The anchor rod (cable) is simulated by adopting a structure unit with a built-in cable in FLAC, and the mechanical and geometric parameters of the anchor rod (cable) unit are shown in Table 2.
Table 2 structural unit mechanics and geometry parameters of anchor rods (cables)
Wherein L is the length of the anchor rod (rope); d is the diameter of the anchor rod (rope); e is Young's modulus; pg is the perimeter of the outer ring of the cement paste; ft is the tensile yield strength; cg is the cohesive force of the cement paste in unit length; kg is the shear rigidity of cement paste in unit length;
The vertical displacement and horizontal displacement distribution cloud patterns simulated by the inverted well construction chamber supporting scheme are shown in fig. 14 to 17.
As can be seen from fig. 14 and 15, under the supporting condition, the vertical displacement of the large-section chamber is 461mm, which is reduced by 989mm and about 68% compared with the non-supporting condition; conventional section chambers also tend to be reduced by 471mm, approximately 93%. As can be seen from FIGS. 16 and 17, the horizontal displacement of the large-section horsehead door and the conventional-section horsehead door is 41mm and 9.6mm respectively, and the horizontal displacement is reduced by 148mm and 13.4mm respectively. The roof bolts (ropes) of the chamber are arranged in a staggered manner and act together with the surrounding rock of the shallow roof to form a bearing arch structure, so that the strength of the surrounding rock of the roof is improved, and further the vertical and horizontal displacement of the surrounding rock of the roof is effectively reduced.
The reverse well construction chamber support plan simulation plastic zone is shown in fig. 18 and 19. As can be seen from the figure, the large-section, conventional-section chamber surrounding rock is in a shear failure state under the supporting condition, and the range of shear failure is reduced compared with that under the non-supporting condition. The breaking depth of the top plate of the large-section and conventional-section chamber is respectively 10m and 5.6m, the same ratio is reduced by 14m and 1.7m, and the breaking depth of the two sides is respectively 7.4m and 3.7m, and the same ratio is reduced by 6.1m and 0.8m. The anchor rod (rope) provides compressive stress for the top plate and the shallow surrounding rock of the two sides through the anchoring effect with the complete surrounding rock of the deep part, improves the strength of the surrounding rock, enhances the stability, controls the deformation and the damage of the surrounding rock, limits the damage and the expansion of the surrounding rock of the deep part and reduces the range of a plastic region.
3.4 Control Effect of surrounding rock
In the actual tunneling process of the construction chamber of the reverse well of the deepening section of the XXX ore secondary horizontal return air vertical well, the construction method and the supporting scheme are combined. After tunneling for a period of time, the deformation of the top plate and the two sides of the conventional section chamber gradually tends to be stable, and the deformation of the top plate and the bottom plate of the chamber is basically controlled within 1 mm/d; the accumulated sinking value of the top plate of the large-section chamber is 132mm, the accumulated value of the relative displacement of the two sides is 74mm, the bottom plate has no obvious swelling phenomenon, and the control effect of surrounding rock of the reverse well construction chamber of the deepening section of the two horizontal return air vertical shafts of XXX ores can be seen to be good in a controllable range.
4. Conclusion(s)
1) The rock formation of the top plate of the reverse well construction chamber of the deepening section of the XXX mine secondary horizontal return air vertical shaft is softer and low in strength, and is a main influencing factor for deformation and damage of surrounding rocks, and the vertical shaft excavation and the dimensional change of the chamber are also important factors for influencing deformation and damage of the chamber.
2) The maximum vertical displacement of the reverse well construction chamber occurs at the top plate, the vertical displacement of the large-section chamber and the vertical displacement of the conventional-section chamber are 1450mm and 505mm respectively, the excavation space of the large-section chamber is large, surrounding rock is greatly disturbed, and the top plate rock stratum is positioned in a plastic area formed by vertical shaft excavation, so that the vertical displacement of the top plate of the large-section chamber is far greater than that of the conventional-section chamber.
3) The maximum horizontal displacement of the reverse well construction chamber occurs at a distance of the top plate and is in an extrusion state towards the vertical central line of the chamber, and the reason is that the top plate rock stratum is softer, and the horizontal movement space is provided for the top plate by the vertical shaft excavation and the height change of the reverse well construction chamber.
4) The key of the stability control of the surrounding rock of the reverse well construction chamber is to strengthen the control of the surrounding rock of the top plate and reduce disturbance to the surrounding rock of the top plate in the construction process, and provide corresponding supporting design schemes and construction procedures according to the section sizes of different chambers, so that the bearing capacity of the surrounding rock of the large-section reverse well construction chamber can be effectively improved.
5) The construction technology of excavating and supporting in a divided manner is adopted, and the top of the large-section chamber is reinforced and supported, so that the problems that the surrounding rock of the large-section chamber for the reverse well construction is serious in deformation, the stability of the roof rock stratum is poor, the vertical displacement of the roof surrounding rock is large in the service process and the like can be effectively solved.
Claims (4)
1. The construction method of the large-section reverse well construction chamber is characterized by comprising the following steps of:
Step A: determining an auxiliary roadway construction point in one roadway adjacent to the large-section chamber to be excavated according to the preset position of the large-section chamber to be excavated;
And (B) step (B): at the auxiliary roadway construction point, tunneling upwards along a preset bottom plate at the bottom of the large-section chamber to be excavated, and changing the tunneling direction when tunneling to the point that the top point of the large-section chamber to be excavated is on the same horizontal line: tunneling construction is conducted to the top position of the large-section chamber to be excavated along the horizontal direction; supporting after construction is completed to obtain an auxiliary roadway;
Step C: taking the auxiliary roadway at the vertex of the large-section chamber to be excavated as a construction point of the large-section chamber; tunneling downwards at the construction point of the large-section chamber according to an arch radian preset at the top of the large-section chamber to be excavated, and supporting after construction is completed to obtain a conventional section chamber (1); the width of the conventional section chamber (1) is smaller than that of the large section chamber to be excavated, and the height of the conventional section chamber (1) is smaller than or equal to the arch height of the large section chamber to be excavated;
Step D: continuing tunneling according to the preset arch shape and size of the large-section chamber to be excavated, wherein a tunneling area (2) comprises areas from two sides of the conventional section chamber to the preset top and the edges between the two sides of the large-section chamber to be excavated, and the lower boundary of the tunneling area (2) and the bottom of the conventional section chamber are on the same horizontal plane; supporting after construction is completed;
step E: dividing two sides of the large-section chamber to be excavated into two or more construction layers from top to bottom according to the design size of the large-section chamber to be excavated, tunneling downwards in layers, supporting after each layer of excavation is completed, tunneling the next layer after the supporting is completed, and completing construction of the large-section chamber after the last layer of supporting is completed;
In the step C, when the conventional section chamber (1) is supported, the top and the two sides of the conventional section chamber (1) are supported by using round steel anchors with phi 16mm multiplied by 2000mm, and the interval of the round steel anchors is 1100mm multiplied by 1000mm; the top of the conventional section chamber (1) is reinforced and supported by using anchor cables with phi 21.6mm multiplied by 6500mm, and the interval row spacing of the anchor cables is 2000mm; the anchor cables and the round steel anchor rods are arranged in staggered mode;
In the step C, when the large-section chamber is supported, anchors are adopted to support the top and two sides of the large-section chamber, the row spacing between the anchors at the top of the large-section chamber is 1000mm multiplied by 1000mm, and two adjacent anchors are connected by adopting a steel bar ladder beam welded by phi 14mm round steel; the row spacing of the anchor rods of the two sides of the large-section chamber is 800mm multiplied by 1000mm, and the anchor rods are vertical to the two sides of the large-section chamber;
the top of the large-section chamber is reinforced and supported by anchor cables with phi 21.6mm multiplied by 8000mm, and the distance between the anchor cables is 2000mm;
The roof bolts used at the top of the large-section chamber and the two sides of the large-section chamber are all left-handed screw steel bolts with phi of 20mm multiplied by 2500 mm.
2. The method of constructing a large section reverse well construction chamber according to claim 1, wherein in step C, the width of the conventional section chamber is equal to 1/2 of the width of the large section chamber to be excavated; the height of the conventional section chamber is equal to the arch height of the large section chamber to be excavated.
3. The construction method of the large-section reverse well construction chamber according to claim 1, wherein in the step E, two sides of the large-section chamber to be excavated are divided into a first step (3), a second step (4) and a third step (5), and 3 construction layers are excavated downwards; after the first step (3) is tunneled, the first step (3) is tunneled continuously to the auxiliary roadway, so that the first step (3) is communicated with the auxiliary roadway, and dregs generated in the construction process are conveniently transported out of the auxiliary roadway.
4. The construction method of the large-section reverse well construction chamber according to claim 1, wherein in the step B, in the process of the auxiliary roadway heading upwards, the heading direction is adjusted according to the target position of the large-section chamber to be excavated.
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