Safe and efficient blocking construction method for high-depth draw shaft

Abstract

The invention belongs to the technical field of mine engineering, and particularly relates to a safe and efficient plugging construction method for a high-depth draw shaft, which comprises the following steps: expanding and excavating a chamber under the draw shaft, constructing a reinforced concrete straight wall in the chamber, arranging an I-shaped steel top guard on the top of the straight wall, mounting an anchor rod on the wall above the straight wall, and fixedly connecting the exposed end of the anchor rod with a reinforcing mesh; a bottom formwork is erected at the bottom of the I-shaped steel top guard, a plurality of water drainage pipes and grouting pipes are arranged in the range of a shaft of the draw shaft, the lower ends of the water drainage pipes and the grouting pipes penetrate through the bottom formwork and are fixed to the I-shaped steel, and the upper ends extend to the deep position of the shaft of the draw shaft; grouting is conducted on the bottom formwork through a grouting pipe, a concrete layer with the thickness of 2 m is formed, and a drop shaft lower opening is closed; a grouting stone body with the thickness of 8 m is formed in the draw shaft through the grouting pipe by adopting micro-expansion grouting; and filling graded broken stones into the shaft from the upper part of the winze shaft until the upper part of the shaft is filled to finish plugging. The filling structure is high in safety and reliability, hydrostatic pressure is effectively controlled, and the self-bearing capacity of the filling structure is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mine engineering, and particularly relates to a safe and efficient plugging construction method for a high and deep chute. BACKGROUND

[0002] In the process of metal and non-metal mine exploitation, chute collapse and caving accidents may occur due to various reasons, resulting in the inability to continue using the shaft and the need to abandon it. Specifically, the main reasons for the destruction of the chute include: 1) a large amount of water inflow in the shaft (such as the final acceptance water inflow of 5.74 m³ / h in some cases), which increases the moisture content of the ore and forms high mobility materials; at the same time, water inflow also weakens the shaft wall rock mass, aggravating the risk of shaft deformation and destruction; 2) frequent material running accidents: such as two serious material running accidents that occurred in the ore discharge chamber at the bottom of the chute, which were caused by fine material size, high moisture content, high material level, and the sudden collapse of the local arch, resulting in impact load and damage to the bottom structure; 3) insufficient structural safety, the original design of the bottom structure has insufficient bearing capacity and cannot withstand the impact of high mobility materials; the brittle failure of plain concrete under dynamic impact.

[0003] After the chute collapses, a new chute usually needs to be constructed at a new location. In order to reduce the safety risks such as further collapse of the shaft wall, disorder of the water and gas channel, and influence on the geological stability caused by the abandoned chute, it is necessary to fill and plug the old chute. Therefore, how to effectively plug the upper part of the shaft while preserving the possible function of the lower structure is a technical problem that technicians in the field have been concerned about. During the mining period, the unloading station has already installed engineering equipment, and the concrete can only be filled into the chute through the unloading station platform, resulting in uneven material density and difficulty in ensuring the filling quality. The existing traditional chute plugging method mainly has the following technical defects: 1. High risk of instability of the bottom pressure structure: the upper large load easily causes shear failure of the bottom plugging structure during single concrete pouring or waste rock filling. 2. Static water pressure weakens self-bearing capacity: the static water pressure generated by the water in the shaft significantly reduces the effective stress of the gravel plugging body, weakening its self-bearing capacity. 3. Poor long-term stability: large waste rock filling easily forms voids, has low density, and is difficult to form an effective pressure arch, and is prone to long-term instability. 4. High cost: the consumption of full-section concrete pouring materials is large, and the transportation and construction costs are high. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a multi-layer composite plugging technology that solves the problems of structural instability, static water pressure influence, poor long-term stability, and high cost in high and deep chute plugging through the synergistic effect of "rigid bearing layer + drainage system + flexible filling body".

[0005] The present application solves the problem by adopting the technical solution of: A safe and efficient plugging construction method for a high and deep chute, comprising: S1: expanding the chute at a position of -398 meters below the chute to form a chamber for plugging operation; S2: constructing a straight wall of reinforced concrete structure along the surrounding rock in the chamber, the straight wall being embedded in the surrounding rock by a depth of ≥60 cm; S3: installing anchor rods on the wall above the straight wall, the anchor rods being arranged at an interval of 0.5 m between them, with 0.5 m exposed, and the outer ends of the anchor rods being welded and fixed with a steel mesh, which is arranged at the lower opening of the chute; S4: arranging I-beam roof protection on the top of the straight wall, wherein the I-beams are arranged at an interval of 0.3 m within the range of the chute shaft, and the interval is widened to 0.5-0.7 m outside the range of the shaft; and the I-beam roof protection is fixed with the steel bars of the straight wall; S5: supporting a bottom formwork at the bottom of the I-beam roof protection, and arranging a plurality of drainage pipes and grouting pipes within the range of the shaft of the chute, the lower ends of the drainage pipes and grouting pipes penetrating through the bottom formwork and being fixed with the I-beam, and the upper ends extending to the deep part of the shaft of the chute; S6: connecting the grouting pipes with a grouting machine to inject grout above the bottom formwork, forming a 2 m thick concrete layer above the bottom formwork to close the lower opening of the chute; S7: after the strength of the concrete layer reaches the requirement, forming an 8 m thick grouting stone body in the chute by using micro-expansion grouting through the grouting pipes, the grouting stone body being poured in two times, with a single pouring thickness of 4 m; S8: after the grouting stone body hardens, filling graded gravel into the shaft from the upper part of the shaft of the chute, and filling to the upper part of the shaft to complete the plugging.

[0006] The present application has the beneficial effects compared with the prior art by adopting the above structure: The present application has high safety and reliability, the rigid frame at the bottom provides strong shear resistance, the plugging structure is stable against sliding, the static water pressure is effectively controlled by the accumulated water drainage system composed of the graded gravel and the drainage pipes, the self-bearing capacity of the filling structure is improved, the structure of the straight wall at the bottom, the I-beam, the anchor rod and the steel mesh is convenient for construction, the filling material is locally sourced, and the plugging cost is low.

[0007] As a preferred further technical solution of the above structure: The drainage pipes are uniformly and symmetrically arranged along the circumference of the shaft of the chute, and the upper end of the drainage pipe is wrapped with geotextile when installed; after the construction of the gravel plugging body is completed, a drilling machine is extended into the drainage pipe to drill through the geotextile and reach the fine gravel cushion.

[0008] The drilling angle of the anchor rod can be adjusted within a range of ±2° according to the surrounding rock conditions on site to ensure the anchoring effect.

[0009] The graded broken stone sealing body uses the excavated and masonry waste stone, the lower part 10m is the fine broken stone cushion with the particle size of 5mm-10mm, and the upper part 40mm-500mm is the filling layer. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is the schematic diagram of the expanded chamber of the present application; Figure 2 is the schematic diagram of the arrangement of the drain pipe in the chute of the present application; Figure 3 is the schematic diagram of the arrangement of the I-beam roof protection of the present application; Figure 4 is the schematic diagram of the connection structure of the steel mesh at the bottom of the chute of the present application; Figure 5 is the schematic diagram of the bottom support of the sealing structure at the bottom of the chute of the present application; Figure 6 is the schematic diagram of the arrangement of the anchor rod and the steel mesh of the present application; Figure 7 is the schematic diagram of the material filling of the present application; Figure 8 is the schematic diagram of the overall structure after sealing of the present application.

[0011] In the figure: 1, chute; 2, chamber; 3, grouting pipe; 4, drain pipe; 5, straight wall; 6, I-beam roof protection; 7, anchor rod; 8, plane steel mesh; 9, arc steel mesh; 10, concrete layer; 11, grouting stone body; 12, graded broken stone. DETAILED DESCRIPTION

[0012] The sealing of the main chute of Tangshan Shougang Malan Zhuang Iron Mine is designed to fill the shaft above-398m, and the overall sealing scheme is the sealing scheme of reinforced concrete straight wall+I-beam+long anchor rod+concrete+grouting sealing body+broken stone filling.

[0013] The design idea of the construction method of the present application is: The overall treatment scheme is guided by the idea of "using local materials, overall effective sealing, secondary reinforcement support, and effective drainage", and the sealing scheme optimization of the shaft is mainly considered from the following four aspects: 1) Using local materials, effectively reducing the sealing cost and optimizing the sealing efficiency. In order to prevent the local shaft wall collapse of the upper shaft under the conditions of long-time vacancy, water soaking and the disturbance of the long-term ore drawing of the newly excavated 1# main chute 1, which may cause potential safety risks to the future ore unloading chamber 2 operation, the broken stone is used to fill the 1# main chute 1. In order to effectively reduce the sealing cost and optimize the sealing efficiency, the excavated and masonry waste stone is discussed to be used as the main filling material after screening, which not only reduces the transportation distance of the filling material and avoids the occupation of the limited lifting transportation resources, but also reduces the cost of the filling material.

[0014] 2) Overall effective plugging, to ensure the safe operation of the subsequent wellbore lower chamber 2. In the lower section of the main chute 1, concrete + cement grouting stone body is used to effectively plug the upper crushed stone plugging section, to ensure the long-term stability and effectiveness of the main plugging section, and to ensure the safe operation of the lower chamber 2.

[0015] 3) Secondary reinforcement support, to ensure the overall stability of the plugging structure under adverse conditions. In the chute 2 on the lower side of the wellbore, a secondary reinforcement support form of concrete straight wall 5 + I-steel + long anchor rod 7 + steel mesh + concrete bottom sealing layer is used to ensure the overall stability of the plugging structure under adverse conditions.

[0016] 4) Effective drainage, to ensure the effective self-bearing of the upper crushed stone filling body. The crushed stone filling body in the wellbore will form a pressure arch within a certain range due to its own friction with the well wall, forming an effective self-bearing structure. Water accumulation in the wellbore will cause a decrease in the effective stress in the crushed stone body, greatly weakening the self-bearing capacity and significantly increasing the bearing pressure of the bottom plugging structure. Therefore, effective drainage measures are taken to effectively drain the water in the wellbore, fully utilize the self-bearing capacity of the upper crushed stone filling body, and ensure the long-term stability of the plugging structure.

[0017] The present application will be further described in conjunction with the examples, the purpose of which is only to better understand the content of the present application, therefore, the examples do not limit the protection scope of the present application.

[0018] Referring to Figures 1 to 8 The high-depth chute 1 safe and efficient plugging technology provided by the present application has the following specific construction steps: S1: The chute 1 is expanded at the -398m position of the chute 1 to form a chamber 2 for plugging operation.

[0019] S2: The bottom chamber 2 of the chute 1 is cleaned to ensure the safety of the working surface, and a reinforced concrete straight wall 5 is designed and constructed in the chamber 2. C30 reinforced concrete is used, with a thickness of 60cm. The straight wall 5 needs to be embedded in the stable surrounding rock by at least 60cm to ensure the smoothness of the surface of the straight wall 5 and provide the main shear resistance, laying the foundation for subsequent installation.

[0020] S3: Anchor rods 7 are installed on the well wall above the straight wall 5. The anchor rods 7 are spaced at an interval of 0.5m, with an exposed length of 0.5m. The outer end of the anchor rod 7 is welded and fixed with a steel mesh, which is arranged at the lower opening of the chute 1.

[0021] Anchor rod 7: φ25mm threaded steel anchor rod 7, total length 5.0m, exposed length 0.5m for welding steel mesh, to enhance the integrity of the surrounding rock and the poured concrete.

[0022] Optionally, the steel mesh includes two types of plane steel mesh 8 and arc steel mesh 9. The plane steel mesh 8 is made by weaving or binding horizontal and vertical steel bars, and is arranged in several layers according to the distance between the I-beam roof 6 and the roof of the chamber. The arc steel mesh 9 is arranged according to the shape of the chamber 2, and can be attached to the surface of the roof. The steel mesh is made of φ25mm threaded steel.

[0023] The borehole on the roof rock above the straight wall 5 has a diameter of 38mm-42mm, and can be adjusted and optimized within the range of ±2° inclination according to the site surrounding rock conditions. The density is 0.5m interval (0.5m interval is arranged from the top view and side view).

[0024] S4: The I-beam roof 6 is arranged on the top of the straight wall 5, wherein the distance between each I-beam in the range corresponding to the shaft of the chute 1 is 0.3m, and the distance outside the shaft range is widened to 0.5m-0.7m; the I-beam roof 6 is fixed with the steel bars of the straight wall 5.

[0025] The I-beam roof 6 adopts I63b I-beam, which is arranged along the axis direction of the ore discharging chamber 2 to form a support beam on the top of the chamber 2.

[0026] S5: The bottom formwork is arranged at the bottom of the I-beam roof 6, and several drainage pipes 4 and grouting pipes 3 are arranged in the shaft range of the chute 1. The lower end of the drainage pipe 4 and the grouting pipe 3 penetrates the bottom formwork and is fixed with the I-beam, and the upper end extends to the deep part of the shaft of the chute 1.

[0027] The grouting pipe 3 adopts φ110mm steel pipe or PVC pipe. In this scheme, the grouting pipe 3 is embedded by pouring concrete, and the grouting pipe 3 is arranged along the shaft of the chute 1, which can be arranged at the middle position of the shaft, and the length is more than 12m, which is higher than the top elevation of the grouting stone body 11; The drainage pipe 4 adopts φ110mm PVC pipe, which is arranged uniformly and symmetrically along the circumference of the shaft, preferably four, and is firmly bound on the I-beam at the bottom by iron wire; since the water seepage inside the chute 1 needs to be discharged, the drainage pipe 4 needs to extend out of the concrete pouring layer and into the backfilled cushioned gravel layer, and the length is about 12m, which is set according to the thickness of the grouting layer to ensure that the upper end extends to 200mm-300mm above the top surface of the future grouting layer.

[0028] S6: The grouting machine is connected to the grouting pipe 3, and grouting is performed above the bottom formwork to form a 2m thick concrete layer 10 above the bottom formwork to close the lower opening of the chute 1.

[0029] The concrete layer 10 is integrated with the I-beam to form a solid bottom plate, and the grouting material can be C30 micro-expanding concrete.

[0030] S7: After the concrete layer 10 reaches the required strength, micro-expanding grouting is used through the grouting pipe 3 to form a 8m-thick grouting stone body 11 in the chute 1, which is completed in two times with a single pouring thickness of 4m; After the grouting stone body 11 reaches the required strength, grouting is performed from the upper wellhead of the chute 1, and micro-expanding grouting material (such as C30 micro-expanding cement mortar) is prepared and layered poured. Specifically, it is completed in two times with a pouring thickness of 4m each time. After the first layer (4m thick) is poured, it is allowed to have a certain strength (to avoid being washed away) before the second layer (4m thick) is poured.

[0031] Thus, the total thickness of the overall concrete sealing layer reaches 8m, forming an effective upper sealing layer. The pouring process needs to be continuous to avoid interruptions and the formation of cold joints, and then the grouting stone body needs to be kept moist and maintained. The grouting stone body 11 is completely hardened after about a month of maintenance.

[0032] S8: After the grouting stone body 11 is hardened, graded gravel 12 is filled into the shaft from the upper wellhead of the chute 1, forming a gravel filling layer above the grouting stone body 11. When filling, the material is continuously and uniformly discharged from the upper wellhead of the chute 1 until the entire upper shaft space is filled. Similarly, a sieve is used and the material is discharged in a dispersed manner. A sieve is provided at the discharge port to prevent oversized materials from being mixed in and to avoid concentrated pouring at a single point. Specifically, the lower part of the gravel layer is a fine gravel cushion layer with a particle size of 5-10mm single particle size graded gravel; subsequent pouring from the upper wellhead can be directly performed with a particle size requirement of 40mm-500mm and a thickness of 10m. The graded gravel 12 with a particle size of 40-500mm can be obtained by screening mine excavation waste stones.

[0033] Based on the example of the 1# main chute 1 of Malanzhuang Iron Mine, structural stability calculation and numerical simulation (FLAC3D) show that the overall sealing structure is stable, the maximum displacement of the surrounding rock is only -2.89x10-4m, the compressive stress of the bottom concrete layer 10 is ≤0.27MPa, and the tensile stress is ≤0.18MPa, which is far below the material strength. The gravel body forms a clear pressure arch, and the bottom pressure is significantly reduced.

[0034] Load transfer: The gravel and shaft wall friction (friction angle of 24°) effectively share the vertical load, and the drainage hole ensures no water accumulation, with zero hydrostatic pressure (the most unfavorable working condition value is 7573.75 kN).

[0035] S9: The upper part of the chute 1 is filled with 40mm-500mm coarse gravel as a cover, and the sealing is completed.

[0036] After the gravel filling is completed, the drainage pipe 4 wrapped with geotextile is drilled into the cushion layer and reinserted to effectively drain the accumulated water and reduce the hydrostatic pressure.

[0037] Advantages of the present application: 1)Significant improvement in safety and reliability: Strong anti-sliding stability: The rigid frame at the bottom (straight wall 5 + anchor rod 7 + concrete) provides strong shear resistance, and theoretical calculations show that its anti-sliding force (49979.88 kN) can be 3.91 times the sliding force (12790.40 kN).

[0038] Effective control of hydrostatic pressure: The drainage system ensures timely drainage of accumulated water, maintains the effective stress of the gravel, and improves its self-bearing capacity.

[0039] Optimized load dispersion: The graded gravel 12 fills in to form a pressure arch effect, significantly reducing the pressure transmitted to the bottom structure.

[0040] Good overall stability: Numerical simulation results show that the surrounding rock deformation is minimal, the supporting structure is uniformly stressed and has low levels (concrete compressive stress ≤ 0.27 MPa, tensile stress ≤ 0.18 MPa; anchor rod 7 stress ≤ 4.03 MPa; I-beam bending moment ≤ 2.94 kN·m).

[0041] 2)High efficiency and convenience in construction: Modular design is clear (straight wall 5 → anchor rod 7 network → I-beam → concrete → drainage pipe 4 → grouting → gravel), with clear procedures, making it easy to organize construction.

[0042] 3)Significant economic benefits: Local materials: The upper gravel plugging body uses a large amount of screened excavation waste rock, significantly reducing material costs and transportation pressure.

[0043] Material optimization: 8m micro-expansion grouting replaces the full concrete section, saving about 30% of material costs.

[0044] Low maintenance cost: The structure is long-term stable and reliable, reducing the need for later maintenance.

[0045] 4)Wide range of applications: Especially suitable for high-risk chute 1 plugging projects with large depth (> 150m), large diameter (> 3m), and water conditions.

[0046] Economic benefits: Compared with the traditional full concrete plugging scheme, the material cost is saved by 30% (mainly due to the replacement of concrete with 8m grouting and the use of a large amount of waste rock), and the construction efficiency is high, ensuring the timely development of subsequent mine projects (new chute 1 excavation).

[0047] The above only describes the preferred and feasible embodiments of the present application, and is not intended to limit the scope of the present application. Any equivalent changes made in accordance with the content of the present application specification and its drawings are included within the scope of the present application.

Claims

1. A safe and efficient sealing method for deep well chutes, characterized in that, include: S1: The chute (1) is enlarged at a depth of -398 meters below the chute (1) to form a chamber (2) for sealing operations. S2: Construct a straight wall (5) of reinforced concrete structure along the surrounding rock in the chamber (2), the straight wall (5) being embedded in the surrounding rock to a depth ≥60cm; S3: Install anchor rods (7) on the well wall above the straight wall (5). The spacing between anchor rods (7) is 0.5m, and 0.5m is exposed. The outer end of the anchor rod (7) is welded and fixed to the steel mesh. The steel mesh is set at the bottom of the chute (1). S4: Install an I-beam top (6) on the top of the straight wall (5), wherein the spacing between each I-beam is 0.3m within the range corresponding to the shaft of the chute (1), and the spacing is widened to 0.5m-0.7m in the area outside the shaft range; fix the I-beam top (6) to the reinforcing bars of the straight wall (5); S5: A bottom template is set at the bottom of the I-beam top (6), and several drain pipes (4) and grouting pipes (3) are set within the shaft of the chute (1). The lower ends of the drain pipes (4) and grouting pipes (3) penetrate the bottom template and are fixed to the I-beam, while the upper ends extend to the depth of the shaft of the chute (1). S6: The grouting machine is connected to the grouting pipe (3) and grout is injected onto the bottom template to form a 2m thick concrete layer (10) on the bottom template, and the bottom of the chute (1) is sealed. S7: Once the concrete layer (10) reaches the required strength, micro-expansion grouting is used again through the grouting pipe (3) to form an 8m thick grouting stone body (11) in the chute (1). The grouting stone body (11) is poured in two stages, with a single pouring thickness of 4m. S8: After the grouting stone body (11) has hardened, fill the wellbore with graded crushed stone (12) from the upper part of the wellbore (1) until the upper part of the wellbore is filled, thus completing the sealing.

2. The safe and efficient sealing construction method for deep wells according to claim 1, characterized in that: The drain pipe (4) is evenly and symmetrically arranged around the well shaft of the chute (1). When the drain pipe (4) is installed, the upper end is wrapped with geotextile. After the construction of the crushed stone sealing body is completed, a drilling rig is used to extend into the drain pipe (4), drill through the geotextile and drill to the fine crushed stone cushion layer.

3. The safe and efficient sealing construction method for deep ore passes (1) according to claim 1, characterized in that: The drilling angle of the anchor rod (7) can be adjusted within ±2° according to the surrounding rock conditions on site to ensure the anchoring effect.

4. The safe and efficient sealing construction method for deep wells according to claim 1, characterized in that: The graded crushed stone (12) sealing body uses locally sourced excavated waste stone, with a 10m lower layer of fine crushed stone with a particle size of 5mm-10mm and an upper layer of 40mm-500mm.

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