Method for constructing underground sealing wall roof contact through reverse construction method

Abstract

The invention discloses a top-down construction method for underground sealing wall roof contact. The top-down construction method comprises the following steps that S1, a reasonable position is selected as a sealing wall site; s2, selecting construction parameters of the sealing wall according to a design process; s3, carrying out picking, stripping and bottom shoveling on the roadway at the position of the closed wall; s4, groove cleaning and reinforcing mesh construction; s5, mounting a water filter pipe; s6, formwork erecting and pouring are conducted; and S7, concrete curing. According to the reverse construction method, the upper half portion of the sealing wall is firstly poured, then the lower half portion of the wall body is poured, concrete is poured in time during reverse construction, the functions of a roadway top plate inclined face and a formwork inclined face can be effectively achieved, the dead weight of concrete is better utilized, the concrete on the contact face is compacted, and therefore the better sealing effect is achieved. The combination face between the wall body and the top plate is creatively divided into two inclined faces, self-compaction of concrete is achieved, key parts for sealing water leakage of the wall are blocked, the construction cost is saved, the construction time is shortened, and the method is simple, efficient and practical.

Description

Technical Field

[0001] The invention relates to the technical field of filling mining, in particular to a method for constructing an underground closed wall top connection by reverse construction. Background Art

[0002] In order to solve the safety hazards of underground goaf and surface collapse, using tailings to fill and manage underground goaf is the most economical and direct method. Closing the underground goaf is a necessary condition before filling with tailings. Generally, all mines use reinforced concrete walls as a means of closure. This requires that the filling and closing walls of underground goaf should reach the corresponding compression and waterproof levels. The filling and closing walls of underground goaf adopt reinforced concrete structures, which are compression and waterproof. According to the design calculation, the compression resistance is 0.2-05MPa, and the waterproof level is above level 2.

[0003] The closed wall is generally selected in the area where the rock is relatively intact. The top, bottom and both sides of the tunnel where it is located are excavated into wedge-shaped grooves. The function of the grooves is to embed the wall into the surrounding rock of the tunnel to ensure the overall stability of the wall. In order to ensure that the closed wall can resist the pressure of the later filling body, the wedge-shaped groove is designed to be similar to the shape of a "water bottle stopper". The specifications are larger near the inner side of the wall (the side facing the filling material) and slightly smaller on the outer side of the wall. Piles are constructed around the grooves, and round steel is inserted. 1-2 vertical steel meshes are arranged in the wall and connected to the round steel of the pile eyes. Before pouring concrete, a water filter should also be installed. According to different compressive strength grades, the concrete strength grade is selected as C20 or C30.

[0004] Generally, the volume of the pressure-resistant and waterproof enclosed wall in the mine is not large, and it is all reinforced concrete wall. Because the working surface in the mine is narrow, most of them are constructed by conventional methods of manual pouring. The mixed concrete is poured into the formwork, and the concrete is poured from bottom to top. After vibrating, the enclosed wall is poured.

[0005] The key to wall construction is pouring concrete between the wall and the tunnel roof. Because the groove and the closed wall are larger inside and smaller outside, during normal construction, workers work outside the wall, and it is inconvenient to deliver concrete from the outside to the top of the wall. During vibration, due to gravity, the concrete at the top sinks downward and forms cracks. In addition, the volume of the concrete itself shrinks when solidifying, thus forming through cracks in the top concrete wall, which will inevitably cause water seepage and leakage after filling.

[0006] There are usually three ways to solve this problem. The first method is to pour into a small well. A pedestrian well and a pouring well are constructed above the tunnel at the top of the tunnel and behind the wall, and the two wells are connected to each other. When the concrete wall and the tunnel top plate are poured and connected, the mixed concrete is lifted from the pedestrian well to the connecting tunnel, poured into the small well just above the wall, poured into the part where the wall and the top plate are connected, and the concrete at the junction of the wall and the top plate is compacted by vibration. The advantage of this method is that the connection is reliable, and the disadvantage is that the construction volume is large, the wall thickness cannot be less than the width of the pouring well, and the scope of application is limited. The second method is to add an expansion agent. That is, when the wall is connected to the top, add a concrete expansion agent when the concrete is mixed. The advantage of this method is simple operation, and the disadvantage is that the expansion agent increases the volume of concrete and is difficult to control, which reduces the strength of the concrete wall. The third method is to use a pressure pump to grout and seal the junction of the wall and the tunnel after the construction of the concrete wall is completed. The advantage of this method is that it is airtight and reliable, but the disadvantage is that the process is complicated and the cost is increased. Therefore, the present application provides a method for constructing an underground closed wall and connecting the top by a reverse method to meet the needs. Summary of the invention

[0007] The purpose of the present application is to provide a method for constructing underground closed wall top connection by reverse construction method, so as to solve the technical problem of leakage of filling material at the top connection of the existing closed wall.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical solution: a method for constructing underground closed wall top connection by reverse construction, characterized in that it comprises the following steps:

[0009] S1. Select a reasonable location as the enclosing wall location: The enclosing wall location should be selected in a section where the tunnel roof is intact, the tunnel section is relatively small, and the rock integrity is good, and the construction site should be close to the transportation distance;

[0010] S2. Select the construction parameters of the closed wall according to the design process: the design thickness of the concrete closed wall, the internal reinforcement arrangement and configuration and other parameters shall be in accordance with the design requirements, the concrete strength grade shall be C30, and the sand, gravel and cement types shall be in accordance with the design requirements;

[0011] S3. Stripping and shoveling are performed on the tunnel at the closed wall position to form a wedge-shaped groove. The groove is divided into three parts, namely the top plate groove, the side plate groove and the bottom groove: the top plate groove is formed by drilling and blasting the top plate to form a slope on the top plate, with a slope of 20-30°, and the slope is high inside and low outside, that is, the slope close to the inner side of the closed wall (the side facing the filling material) is high, and the slope outside the wall is low; the side plate groove is formed by drilling and blasting on both sides of the tunnel to form an annular wedge-shaped groove around the tunnel, with a width of 1.5m and a depth of 0.5m; the bottom groove is shoveled into a 0.4m foundation pit on the bottom plate, with a width of 1.2m and a length equal to the stripping distance on both sides;

[0012] S4. Cleaning the grooves and steel mesh: The floating stones on the side walls of the tunnel must be cleaned, the bottom plate must be cleaned of floating slag and the accumulated water must be drained, and 3 rows of pile holes are drilled on both sides, the middle and the bottom plate of the closed wall, with a pile hole depth of ≥0.5m; ￠32 round steel is inserted into the inner and outer pile holes to fix the formwork, and the concrete steel mesh is fixed in the middle and bottom plate pile holes. ￠16 steel mesh is installed in the wall, and the mesh size is 20cm*20cm. After the steel piles are buried in the bottom plate groove, the closed wall foundation concrete is poured with a thickness of 40cm;

[0013] S5. Install the filter pipe: bury one filter pipe at the height of 0.6m and 1.5m respectively on the closed retaining wall. The filter pipe is 6m long and made of a steel pipe with a diameter of ￠100. Several small holes are drilled at one end of the steel pipe. The end of the steel pipe with holes is placed inside the retaining wall. Two layers of 100-mesh filter cloth are wrapped outside the hole, and non-woven geotextile is used to wrap it in multiple layers and tied tightly with iron wire. A gate valve is installed on the iron pipe outside the retaining wall.

[0014] S6, formwork and pouring: The reverse construction of tunnel enclosed wall concrete is divided into two steps: formwork and pouring; the first step is to pour the upper part of the enclosed wall, which is the key process;

[0015] S61. The first step is to cast the upper part of the enclosed wall: install a template at a height of 1.8m of the enclosed wall, the bottom of the template is an inclined surface, the slope of the inclined surface is opposite to that of the top plate, the slope is 15-20°, the inclined surface is low inside and high outside, that is, the inclined surface close to the inner side of the enclosed wall (the side facing the filling material) is low, and the inclined surface on the outer side of the wall is high; the 1.8m space at the bottom of the template is used as a passage for operators to enter and exit and transport materials; set up a solid operating platform inside the enclosed wall for concrete pouring and compacting of the upper wall, place a horizontal steel mesh 0.2m below the top plate slope, and vibrate and compact the poured concrete and the top plate slope. When pouring concrete at the top plate, consider the shrinkage of the concrete and divide the top pouring work into 2-3 times, each interval is about 3-4 hours, and each vibration must be compacted to the right place;

[0016] S62, the second step of pouring the lower closed wall: after the upper closed wall concrete solidifies, the formwork is removed, and the second step of erecting the formwork, tying the steel bars and pouring the lower part of the closed wall is carried out. The inner and outer sides of the wall are vertically supported, and the middle steel mesh is welded and firmly tied to the anchor piles of the side, top and bottom plates. After the concrete of the joint surface is processed, the concrete is poured. When the concrete of the upper part of the wall is poured, the shrinkage of the concrete is considered, and the pouring work is divided into 1-2 times, and the interval time of each time is about 2-3 hours, and each vibration should be dense and in place;

[0017] S7. Concrete curing: Collect concrete test block samples as required, and carry out curing and testing of the test blocks. Since the humidity underground is high and the humidity changes little, the curing of the closed wall is carried out according to normal regulations.

[0018] As a preferred implementation in this embodiment, in step S61, the closed wall reinforcement should extend beyond the bottom of the concrete to facilitate connection with the lower concrete reinforcement mesh.

[0019] As a preferred implementation in this embodiment, in step S61, after the closed wall is poured, cement slurry can be used to artificially groove and fill the wall at the contact line between the rock mass and the top plate.

[0020] In summary, the technical effects and advantages of the present invention are as follows: the reverse construction method is to first cast the upper part of the closed wall, and then cast the lower part of the wall. During the reverse construction method, concrete is poured in batches, which can effectively play the role of the inclined surface of the tunnel roof and the inclined surface of the template, better utilize the deadweight of the concrete, and compact the concrete on the contact surface, thereby achieving a better sealing effect. The reverse construction process solves the problem of concrete settlement and shrinkage between the wall and the tunnel roof, and creatively resolves the bonding surface between the wall and the roof into two inclined surfaces. When pouring between the two inclined surfaces, the deadweight of the concrete is fully utilized to achieve self-compacting of the concrete and block the key parts of the closed wall that leak. This method saves construction costs, shortens construction time, and is simple, efficient and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is a schematic diagram of a closed wall in the present invention;

[0023] Figure 2 It is a schematic diagram of the construction of the closed wall in the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example: Reference Figure 1-2 A method for constructing underground closed wall top connection by reverse construction, characterized in that it includes the following steps:

[0026] S1. Select a reasonable location as the enclosing wall location: The enclosing wall location should be selected in a section where the tunnel roof is intact, the tunnel section is relatively small, and the rock integrity is good, and the construction site should be close to the transportation distance;

[0027] S2. Select the construction parameters of the closed wall according to the design process: the design thickness of the concrete closed wall, the internal reinforcement arrangement and configuration and other parameters shall be in accordance with the design requirements, the concrete strength grade shall be C30, and the sand, gravel and cement types shall be in accordance with the design requirements;

[0028] S3. Stripping and shoveling are performed at the tunnel at the closed wall position to form a wedge-shaped groove. The groove is divided into three parts, namely the top plate groove, the side plate groove and the bottom plate groove: the top plate groove is formed by drilling and blasting the top plate to form a slope with a slope of 20-30° (the slope is higher than 30°, the inclination is steeper, the concrete has a certain slump, and there will be gaps between the rock and the concrete. The larger the angle, the higher the height from the bottom plate, and the more difficult it is to operate; the slope is lower than 20°, the inclination is gentler, and the inner and outer openings are The height difference is small, and it does not play a "plug" role in safety, so the slope is set to 20-30° most appropriately). The slope is high inside and low outside, that is, the slope close to the inner side of the closed wall (the side facing the filling material) is high, and the slope outside the wall is low; the side plate groove is drilled and blasted on both sides of the tunnel to form an annular wedge-shaped groove around the tunnel. The wedge-shaped groove is embedded with a width of 1.5m and a depth of 0.5m; the bottom groove is shoveled into a 0.4m foundation pit on the bottom plate, with a width of 1.2m and a length equal to the distance between the two sides;

[0029] S4. Cleaning the grooves and steel mesh: The floating stones on the side walls of the tunnel must be cleaned, the bottom plate must be cleaned of floating slag and the accumulated water must be drained, and 3 rows of pile holes are drilled on both sides, the middle and the bottom plate of the closed wall, with a pile hole depth of ≥0.5m; ￠32 round steel is inserted into the inner and outer pile holes to fix the formwork, and the concrete steel mesh is fixed in the middle and bottom plate pile holes. ￠16 steel mesh is installed in the wall, and the mesh size is 20cm*20cm. After the steel piles are buried in the bottom plate groove, the closed wall foundation concrete is poured with a thickness of 40cm;

[0030] S5. Install the filter pipe: bury one filter pipe at the height of 0.6m and 1.5m respectively on the closed retaining wall. The filter pipe is 6m long and made of a steel pipe with a diameter of ￠100. Several small holes are drilled at one end of the steel pipe. The end of the steel pipe with holes is placed inside the retaining wall. Two layers of 100-mesh filter cloth are wrapped outside the hole, and non-woven geotextile is used to wrap it in multiple layers and tied tightly with iron wire. A gate valve is installed on the iron pipe outside the retaining wall.

[0031] S6, formwork and pouring: The reverse construction of tunnel enclosed wall concrete is divided into two steps: formwork and pouring; the first step is to pour the upper part of the enclosed wall, which is the key process;

[0032] S61. The first step is to cast the upper part of the enclosed wall: install the formwork at a height of 1.8m on the enclosed wall. The bottom of the formwork is an inclined plane. The slope of the inclined plane is opposite to that of the top plate, and the slope is 15-20° (if the slope is higher than 20°, the cubic volume of concrete between the end of the inclined plane and the outer rock top plate is small; if the slope is lower than 15°, the concrete at the inner mouth cannot be fully poured in, and a gap is generated when the upper and lower tops are connected. Therefore, it is most appropriate to set the slope to 15-20°). The slope is low inside and high outside, that is, close to the inner side of the enclosed wall (the side facing the filling material). ) is low, and the slope outside the wall is high; the 1.8m space below the template is used as a passage for operators to enter and exit and transport materials; a solid operating platform is set up inside the closed wall for pouring and compacting the concrete of the upper wall, and a horizontal steel mesh is placed 0.2m below the slope of the top plate. The poured concrete and the slope of the top plate must be vibrated and compacted. When pouring concrete at the top plate, the shrinkage of the concrete is considered. The top pouring work is divided into 2-3 times, with an interval of about 3-4 hours each time, and each vibration must be compacted to the right place;

[0033] S62, the second step of pouring the lower closed wall: after the upper closed wall concrete solidifies, the formwork is removed, and the second step of erecting the formwork, tying the steel bars and pouring the lower part of the closed wall is carried out. The inner and outer sides of the wall are vertically supported, and the middle steel mesh is welded and firmly tied to the anchor piles of the side, top and bottom plates. After the concrete of the joint surface is processed, the concrete is poured. When the concrete of the upper part of the wall is poured, the shrinkage of the concrete is considered, and the pouring work is divided into 1-2 times, and the interval time of each time is about 2-3 hours, and each vibration should be dense and in place;

[0034] S7. Concrete curing: Collect concrete test block samples as required, and carry out curing and testing of the test blocks. Since the humidity underground is high and the humidity changes little, the curing of the closed wall is carried out according to normal regulations.

[0035] This reverse concrete construction method is different from the general closed wall concrete pouring in the order of pouring concrete when constructing a closed wall. When pouring a general concrete wall, after the formwork is set up, it starts from the foundation, and pours and vibrates from bottom to top layer by layer, and compacts layer by layer. The reverse concrete construction method is to pour the upper part of the closed wall first, and then pour the lower part of the wall. When pouring concrete in batches during the reverse construction method, it can effectively play the role of the inclined surface of the tunnel roof and the inclined surface of the formwork, better utilize the deadweight of the concrete, and compact the concrete on the contact surface, so as to achieve a better sealing effect. Compared with other methods, it is more cost-saving, optimizes the process, and is simple to operate; the reverse construction method solves the problem of concrete settlement and shrinkage between the wall and the tunnel roof, creatively resolves the joint surface between the wall and the roof into two inclined surfaces, and fully utilizes the deadweight of the concrete when pouring between the two inclined surfaces, so as to achieve self-compacting of the concrete and block the key parts of the closed wall leaking. This method saves construction costs, shortens construction time, and is simple, efficient and practical.

[0036] As a preferred implementation in this embodiment, in step S61, the closed wall reinforcement should extend beyond the bottom of the concrete to facilitate connection with the lower concrete reinforcement mesh.

[0037] As a preferred implementation in this embodiment, in step S61, after the closed wall is poured, cement slurry can be used to artificially groove and fill the wall at the contact line between the rock mass and the top plate.

[0038] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for constructing underground closed wall top connection by reverse construction, characterized in that: The steps include: S1. Select a reasonable location as the enclosing wall location: The enclosing wall location should be selected in a section where the tunnel roof is intact, the tunnel section is relatively small, and the rock integrity is good, and the construction site should be close to the transportation distance; S2. Select the construction parameters of the closed wall according to the design process: the design thickness of the concrete closed wall, the internal reinforcement arrangement and configuration and other parameters shall be in accordance with the design requirements, the concrete strength grade shall be C30, and the sand, gravel and cement types shall be in accordance with the design requirements; S3. Stripping and shoveling are performed on the tunnel at the closed wall position to form a wedge-shaped groove. The groove is divided into three parts, namely the top plate groove, the side plate groove and the bottom groove: the top plate groove is formed by drilling and blasting the top plate to form a slope on the top plate, with a slope of 20-30°, and the slope is high inside and low outside, that is, the slope close to the inner side of the closed wall (the side facing the filling material) is high, and the slope outside the wall is low; the side plate groove is formed by drilling and blasting on both sides of the tunnel to form an annular wedge-shaped groove around the tunnel, with a width of 1.5m and a depth of 0.5m; the bottom groove is shoveled into a 0.4m foundation pit on the bottom plate, with a width of 1.2m and a length equal to the stripping distance on both sides; S4. Cleaning the grooves and steel mesh: The floating stones on the side walls of the tunnel must be cleaned, the bottom plate must be cleaned of floating slag and the accumulated water must be drained, and 3 rows of pile holes are drilled on both sides, the middle and the bottom plate of the closed wall, with a pile hole depth of ≥0.5m; ￠32 round steel is inserted into the inner and outer pile holes to fix the formwork, and the concrete steel mesh is fixed in the middle and bottom plate pile holes. ￠16 steel mesh is installed in the wall, and the mesh size is 20cm*20cm. After the steel piles are buried in the bottom plate groove, the closed wall foundation concrete is poured with a thickness of 40cm; S5. Install the filter pipe: bury one filter pipe at the height of 0.6m and 1.5m respectively on the closed retaining wall. The filter pipe is 6m long and made of a steel pipe with a diameter of ￠100. Several small holes are drilled at one end of the steel pipe. The end of the steel pipe with holes is placed inside the retaining wall. Wrap the outside of the hole with 2 layers of 100 mesh filter cloth and wrap it with multiple layers of non-woven geotextile. Tie it with iron wire. Install a gate valve on the iron pipe outside the retaining wall. S6, formwork and pouring: The reverse construction of tunnel enclosed wall concrete is divided into two steps: formwork and pouring; the first step is to pour the upper part of the enclosed wall, which is the key process; S61. The first step is to cast the upper part of the enclosed wall: install a template at a height of 1.8m of the enclosed wall, the bottom of the template is an inclined surface, the slope of the inclined surface is opposite to that of the top plate, the slope is 15-20°, the inclined surface is low inside and high outside, that is, the inclined surface close to the inner side of the enclosed wall (the side facing the filling material) is low, and the inclined surface on the outer side of the wall is high; the 1.8m space at the bottom of the template is used as a passage for operators to enter and exit and transport materials; set up a solid operating platform inside the enclosed wall for concrete pouring and compacting of the upper wall, place a horizontal steel mesh 0.2m below the top plate slope, and vibrate and compact the poured concrete and the top plate slope. When pouring concrete at the top plate, consider the shrinkage of the concrete and divide the top pouring work into 2-3 times, each interval is about 3-4 hours, and each vibration must be compacted to the right place; S62, the second step of pouring the lower closed wall: after the upper closed wall concrete solidifies, the formwork is removed, and the second step of erecting the formwork, tying the steel bars and pouring the lower part of the closed wall is carried out. The inner and outer sides of the wall are vertically supported, and the middle steel mesh is welded and firmly tied to the anchor piles of the side, top and bottom plates. After the concrete of the joint surface is processed, the concrete is poured. When the concrete of the upper part of the wall is poured, the shrinkage of the concrete is considered, and the pouring work is divided into 1-2 times, and the interval time of each time is about 2-3 hours, and each vibration should be dense and in place; S7. Concrete curing: Collect concrete test block samples as required, and carry out curing and testing of the test blocks. Since the humidity underground is high and the humidity changes little, the curing of the closed wall is carried out according to normal regulations.

2. A method for top connection of underground closed wall by reverse construction according to claim 1, characterized in that: In step S61, the closed wall reinforcement should extend beyond the bottom of the concrete to facilitate connection with the lower concrete reinforcement mesh.

3. The method for top-joining underground closed walls by reverse construction according to claim 1 is characterized in that: In step S61, after the closed wall is poured, cement slurry can be used to artificially fill the wall grooves at the contact line between the rock mass and the top plate.

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