Method for Reinforcing Middle Partition Wall under Condition of Unilateral Backfilling of Double-Hole Air Shaft

Abstract

The present invention discloses a method for strengthening the middle partition wall under the condition of unilateral backfilling of a double-hole air shaft. A plurality of holes are distributed on the middle partition wall designed as a vertical load-bearing member. The strengthening method includes the following steps: S1, increasing the bottom restraint range of the middle partition wall; S2, increasing the wall strength at the holes of the middle partition wall; S3, locally thickening the middle partition wall. On the one hand, by increasing the bottom restraint range of the middle partition wall, blocking the holes on the middle partition wall and locally thickening the middle partition wall, the influence on the non-backfilled side of the middle partition wall is effectively avoided. On the other hand, under the condition of unilateral backfilling, the stress data of the middle partition wall are accurately calculated according to the actual working conditions, so that necessary strengthening treatments can be carried out on the weak positions of each hole and each layer structure of the middle partition wall, effectively enhancing the self-strength of the middle partition wall and reducing deformation to ensure the smooth progress of construction.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel design, and particularly relates to a method for strengthening the middle partition wall under the condition of unilateral filling of a double-hole air shaft. Background Art

[0002] As is well known, working shafts need to be set at the starting and ending points of shield tunnels for the starting and receiving of shields. With the increase in the length of the tunnel, air shafts also need to be set in the middle of the shield tunnel to meet the ventilation requirements of the long tunnel. During the construction period, the air shaft also serves as an intermediate working shaft and undertakes the functions of starting and receiving. At present, a middle partition wall is set in the double-hole air shaft. On the one hand, the middle partition wall separates the air inlet and outlet and the left and right traffic lanes. On the other hand, it reduces the lateral span of the side wall of the air shaft. The forces on the middle partition wall mainly include two parts. One part is the vertical load transmitted from the superstructure and the uniform loads of each layer. The other part is the longitudinal horizontal load transmitted to the middle partition wall after the external water and soil pressure of the air shaft acts on the side wall. Their common point is along the structural axis. Therefore, under normal conditions, the middle partition wall is mainly a compression member in the vertical and horizontal directions, with very small bending moments and shear forces, and the amount of reinforcement in its design is small, and it is not a key member in the design of the air shaft structure.

[0003] Specifically, in order to conduct full-scale tests on shield tunneling and loading in a single-sided air shaft, it is necessary to fill water and soil on one side of the middle partition wall. At this time, the middle partition wall becomes a key member for the overall safety of the structure. Under the condition of unilateral filling, the middle partition wall changes from a compression member to a bending member. Moreover, the closer to the bottom of the middle partition wall, the greater the water and soil pressure, and the greater the resulting bending moment and shear force, resulting in that the middle partition wall designed as a compression member cannot meet the test requirements and needs to be strengthened.

[0004] However, there has been no engineering case or working condition of unilateral filling of a double-hole air shaft in the industry, nor any relevant research or design. How to strengthen the middle partition wall to ensure the smooth completion of full-scale tests on shield tunneling and loading in a single-sided air shaft on the premise of not affecting the relevant processes such as shield receiving and starting on the other side of the middle partition wall and ensuring the safety of the air shaft structure is an urgent problem to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a brand-new method for strengthening the middle partition wall under the condition of unilateral filling of a double-hole air shaft.

[0006] To solve the above technical problem, the technical solution adopted by the present invention is as follows:

[0007] A method for strengthening the middle partition wall under the condition of unilateral filling of a double-hole air shaft. Multiple holes are distributed on the middle partition wall designed as a vertical load-bearing member. The strengthening method includes the following steps:

[0008] S1. Increase the bottom restraint range of the middle partition wall

[0009] Pour backfill materials on both sides of the bottom of the middle partition wall to form a horizontal fixed restraint at the bottom of the middle partition wall;

[0010] S2. Increase the wall strength at the holes of the middle partition wall

[0011] Calculate the stress data of the holes on the middle partition wall in the transverse and longitudinal directions respectively according to the most unfavorable working conditions of the actual filling soil, and apply plugging materials into each hole below the filling soil height on the middle partition wall;

[0012] S3. Locally thicken the middle partition wall

[0013] Divide the middle partition wall into multiple layers from top to bottom, calculate the stress data of each layer on the middle partition wall in the transverse and longitudinal directions according to the most unfavorable working conditions of the actual filling soil, and check the bearing capacity and crack width of the mid-span and ends of each layer of the middle partition wall at the same time. Thicken the parts of the middle partition wall that cannot meet the bearing capacity or normal use requirements according to the check results.

[0014] Preferably, the backfill material is plain concrete, and its backfill height is greater than or equal to 1m. The backfill height takes a reasonable larger value under the condition of not affecting the shield starting and receiving on both sides of the air shaft.

[0015] Preferably, the backfill layers on the opposite sides at the bottom of the middle partition wall are symmetrically arranged. Improve the bottom stability of the middle partition wall.

[0016] Preferably, the middle partition wall includes a bottom plate, a wall body extending upward from the bottom plate, and a plurality of laminates spaced up and down on the wall body. Among them, the plurality of laminates divide the wall body into the underground first layer, the underground second layer... the underground Nth layer distributed in sequence from top to bottom, and a plurality of holes are distributed on the wall body of each layer. With such a setting, the wall body is divided into multiple layers, which is convenient for staff to calculate the wall stress and identify according to different stress conditions, and it is convenient for construction personnel to intuitively know the areas on the middle partition wall that need to be reinforced.

[0017] Specifically, N = 5, and the filling soil height is higher than the underground first layer; in S2, reinforce the bars around the holes in the underground third layer to the underground fifth layer, and pour concrete with the same grade as the wall body in the corresponding holes to form an integral reinforced concrete structure with the wall body. With such a setting, the middle and lower parts of the middle partition wall are subjected to relatively large transverse loads. Pouring the holes with concrete of the same grade as the middle partition wall effectively increases the strength of the middle and lower parts of the middle partition wall

[0018] Furthermore, reinforce the bars on the non-filling soil side of the wall body corresponding to the underground third layer to the underground fifth layer, and pour concrete after reinforcing the bars.

[0019] Preferably, in S2, concrete of the same grade as the wall is poured into the holes in the lower part of the second basement floor, and the holes in the upper part of the second basement floor are sealed with bricklaying mortar plastering. The holes on the top floor of the middle partition wall are treated with bricklaying mortar plastering, and the strength requirement is not high, only the sealing effect needs to be achieved, the operation is simple, and the construction cost is low.

[0020] Preferably, a thickened layer extending up and down is formed on the side of the wall filled with soil, and the thickened layer includes a first auxiliary retaining wall located on the fourth basement floor and a second auxiliary retaining wall located on the fifth basement floor.

[0021] Specifically, when thickening, support steel bars fixedly connected to the laminates are arranged on the side of the first auxiliary retaining wall or / and the second auxiliary retaining wall filled with soil, and a partition board is arranged between the first auxiliary retaining wall or / and the second auxiliary retaining wall. The thickened layer can be formed by overlapping or composite methods, and can be quickly thickened and formed at the lower part of the wall. If the overlapping method is adopted, it is also convenient for subsequent disassembly, maintenance and replacement.

[0022] In addition, in the fifth basement floor, a plurality of plain concrete rib plates are arranged on the side of the wall that is not filled with soil, and the plurality of rib plates are located between the backfill layer and the laminate at the top of the fifth basement floor.

[0023] Due to the implementation of the above technical solutions, the present invention has the following advantages compared with the prior art:

[0024] On the one hand, the present invention effectively avoids the influence on the side of the middle partition wall that is not filled with soil by increasing the bottom constraint range of the middle partition wall, sealing the holes on the middle partition wall and locally thickening the middle partition wall; on the other hand, under the condition of unilateral soil filling, the stress data of the middle partition wall are calculated according to the actual working conditions, so that the weak positions of the holes and the structures of each layer of the middle partition wall can be strengthened as needed, effectively enhancing the strength of the middle partition wall itself and reducing deformation to ensure the smooth progress of the construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of the double-hole air shaft of the present invention;

[0026] Figure 2 is a schematic diagram of the reinforcement structure of the middle partition wall of the present invention;

[0027] Figure 3 is Figure 2 a left view schematic diagram (partially sectioned);

[0028] Wherein: A, air shaft; t, shield tunnel;

[0029] B, middle partition wall; 1, bottom plate; c1, backfill layer; 2, wall; k, hole; c2, thickened layer; c21, first auxiliary retaining wall; c22, second auxiliary retaining wall; 3, laminate; m, rib plate; n, vertical steel support. Detailed implementation manners

[0030] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will describe the detailed implementation manners of the present application in conjunction with the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0031] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present application.

[0032] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0033] In the present application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0034] In this application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may mean that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature has a lower horizontal height than the second feature.

[0035] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0036] As Figures 1 to 3 shown, the double-hole air shaft structure of this embodiment is a conventional air shaft A, and two shield tunnels t pass through the air shaft A from left to right.

[0037] The middle partition wall B of this embodiment is arranged between the two shield tunnels t on the left and right, and includes a bottom plate 1, a middle partition wall 2, and a layer plate 3.

[0038] Specifically, the bottom plate 1 arches downward, the wall 2 extends vertically upward from the bottom plate 1, and there are five layer plates 3 which are distributed at intervals up and down on the wall 2. Among them, the height of the wall 2 is h1 = 38200 mm, and the thickness is d1 = 1200 mm. The five layer plates 3 divide the wall 2 into the underground layer 1, underground layer 2, underground layer 3, underground layer 4, and underground layer 5 which are distributed in sequence from top to bottom, and a plurality of holes k with different sizes are respectively distributed on the wall 2 of each layer at intervals in the width direction.

[0039] At the same time, after the middle partition wall is reinforced, soil and water are filled on the right side of the wall 2, where the filling height is 25900 mm and the maximum water level height is 25900 mm. Specifically, when the tunneling of the tunnel through the air shaft is completed, the filling height in the air shaft is increased by 5000 mm, and at the same time the water level is lowered by more than 2500 mm to ensure that the horizontal load on the middle partition wall under the loading condition is not higher than that under the tunneling condition.

[0040] The method for reinforcing the middle partition wall under the condition of unilateral filling of the double-hole air shaft in this embodiment includes the following steps: S1, increasing the bottom constraint range of the middle partition wall; S2, increasing the wall strength at the holes of the middle partition wall; S3, locally thickening the middle partition wall.

[0041] In S1, backfill material is poured at the bottom of the middle partition wall to form a backfill layer c1, so as to form a horizontal fixed constraint for the middle partition wall. The backfill material is plain concrete and is poured upward from the top surface of the bottom plate 1, and its backfill height is h2, where h2≥1m. In this embodiment, h2 = 3.5m.

[0042] To improve the stability of the bottom of the middle partition wall, when pouring plain concrete, pouring is carried out synchronously along the left and right sides of the wall body 2 to ensure that the backfill layers c1 on the left and right sides of the wall body 2 are symmetrically arranged.

[0043] In this example, in S2, the force data of each hole k on the middle partition wall in the transverse and longitudinal directions are calculated respectively according to the most unfavorable working conditions of the actual filling soil, and plugging materials are applied in each hole k below the filling soil height on the middle partition wall.

[0044] Specifically, first, steel bars are planted around the holes k located from the 3rd basement floor to the 5th basement floor; then, concrete with the same grade as the middle partition wall is poured into the holes k located from the 3rd basement floor to the 5th basement floor, concrete with the same grade as the wall body is poured into the holes k in the lower part of the 2nd basement floor, and the holes k in the upper part of the 2nd basement floor are plugged with bricklaying mortar plastering. With such a setting, the middle and lower parts of the middle partition wall are subjected to relatively large transverse loads. By planting steel bars and pouring concrete with the same grade as the middle partition wall in the holes, the strength of the middle and lower part voids of the middle partition wall is effectively increased; at the same time, the holes with relatively low strength requirements on the top layer of the middle partition wall are treated with bricklaying mortar plastering, and only the sealing effect needs to be achieved. The operation is simple and the construction cost is low.

[0045] In this example, in S3, the force data of each layer on the middle partition wall in the transverse and longitudinal directions are accurately calculated according to the most unfavorable working conditions of the actual filled water and soil. At the same time, the bearing capacity and crack width of the mid-span and ends of each layer of the middle partition wall are checked. According to the check results, the parts of the middle partition wall that cannot meet the bearing capacity or normal use requirements are thickened.

[0046] According to the data shown in the numerical simulation calculation results, the 4th and 5th basement floors of the middle partition wall have relatively large bending moments and shear forces due to bearing large horizontal loads. Therefore, it is necessary to thicken the 4th and 5th basement floors of the middle partition wall.

[0047] In this embodiment, there are three ways to thicken the wall. The first way is to roughen the surface of the original wall on the side filled with soil and then pour a thickening layer. Steel bars are arranged on the side filled with soil in the thickening layer and connected to the layer board. The thickness of this kind of thickening layer is 800 mm. The second way is to set a partition board between the original wall and the thickening layer. Steel bars are arranged on the side filled with soil in the thickening layer and connected to the layer board. The thickness of this kind of thickening layer is 1200 mm. The third way is to set a partition board between the original wall and the thickening layer, and the thickening layer is plain concrete. The thickness of this kind of thickening layer is 3000 mm. The concrete pouring volume of the first thickening method is the smallest, but it requires roughening and steel bar planting, and the demolition construction is time-consuming and inconvenient. The concrete pouring volume of the second thickening method is moderate, and it requires steel bar planting, and the demolition construction is relatively convenient. The concrete pouring volume of the third thickening method is relatively large, but the implementation is fast and the demolition is convenient. Considering the urgency and convenience of the on-site construction period, the second thickening method is adopted for the fourth basement floor in this example, and the third thickening method is adopted for the fifth basement floor.

[0048] That is to say, the upper and lower thickening layers c2 are formed on the side of the wall 2 filled with soil. The thickening layer c2 includes the first auxiliary retaining wall c21 located on the fourth basement floor and the second auxiliary retaining wall c22 located on the fifth basement floor. The first auxiliary retaining wall c21 is respectively connected to the corresponding upper and lower layer boards 3 through water-swelling waterstop glue at the upper and lower ends, and the thickness of the first auxiliary retaining wall c21 is 1200 mm. The second auxiliary retaining wall c22 extends upward from the backfill layer c1, and water-swelling waterstop glue is respectively arranged between the upper and lower ends of the second auxiliary retaining wall c22 and the backfill layer c1 and the corresponding layer board 3. The thickness of the second auxiliary retaining wall c22 is 3000 mm.

[0049] Vertical steel supports n fixedly connected to the upper and lower layer boards 3 are also arranged on the side of the first auxiliary retaining wall c21 filled with soil, and the sides of the vertical steel supports n are vertically aligned with the sides of the second auxiliary retaining wall c22.

[0050] In addition, in the fifth basement floor, a plurality of triangular rib plates m spaced along the width direction of the wall 2 are fixedly connected between the side of the wall 2 not filled with soil and the top of the backfill layer c1, and each triangular rib plate m is cast with plain concrete.

[0051] In this example, the load - structure model was established using Midas GTS NX software for calculation to obtain the transverse and longitudinal force data of each structure. The model was built with plate elements for the middle partition wall, each floor slab, and the newly added auxiliary retaining wall and ribbed slab. The side wall, bottom slab, and backfill layer were considered as the fixed constraint boundaries for the middle partition wall and each floor slab. The middle partition wall and each auxiliary retaining wall were considered as a composite wall, and compression springs were set between the two walls. The load was calculated according to the most unfavorable working condition during tunneling. Among them, the horizontal water and soil pressure from the first basement floor to the third basement floor was applied to the middle partition wall, and the horizontal water and soil pressure from the fourth basement floor to the fifth basement floor was initially applied to the thickened layer c2. The load on each floor slab was considered as the sum of the self - weight of the soil and water pressure between the floor heights. The earth pressure of the filled soil in the ventilation shaft was calculated according to a unit weight of 20 kN / m2, an internal friction angle of 20°, a cohesion of 0 kN, and a lateral pressure coefficient of 0.49. During the loading period, the influence of loading on the side wall can be offset by lowering the water level. Therefore, the most unfavorable working condition was calculated according to the filling elevation and water level elevation during tunneling.

[0052] In this example, under the most unfavorable working condition, the filling elevation was 25.9 m and the water level elevation was 25.9 m. The calculation model was solved using the standard combination of loads. Both the water and soil loads and the self - weight of the structure were considered as permanent loads, and the load partial coefficient was 1.3 for both. Therefore, the structural force under the basic combination can be calculated by multiplying the structural force under the standard combination by a coefficient of 1.3.

[0053] In summary, using the middle partition wall reinforcement method of this embodiment, the verification results of the force data under the corresponding working conditions are as follows:

[0054] 1. Middle partition wall structure verification

[0055]

[0056] 2. Each floor slab structure verification

[0057] 1). Roof slab

[0058]

[0059]

[0060] 2). First basement floor slab

[0061]

[0062] 3). Second basement floor slab

[0063]

[0064]

[0065] 4). Third basement floor slab

[0066]

[0067] 5) The slab of the 4th basement floor

[0068]

[0069] 3. Check calculation and reinforcement of the auxiliary retaining wall structure

[0070] a. The first auxiliary retaining wall

[0071]

[0072] b. The second auxiliary retaining wall

[0073]

[0074] According to the results of the force calculation, check the flexural and shear bearing capacities of the auxiliary retaining wall according to the width per meter. The self-concrete of the auxiliary retaining wall can meet the requirements of the shear bearing capacity. Therefore, stirrups do not need to be configured for the newly installed auxiliary retaining wall.

[0075] 4. Check calculation and reinforcement of the ribbed slab structure

[0076] The maximum axial force per meter of the ribbed slab is 2890 kN (compression). Calculating the compressive bearing capacity per meter of the ribbed slab according to the plain concrete structure is 6120 kN, and the structure meets the requirements.

[0077] In summary, this embodiment has the following advantages:

[0078] 1. By increasing the bottom restraint range of the middle partition wall, plugging the holes on the middle partition wall and locally thickening the middle partition wall, the influence on the non-backfill side of the middle partition wall is effectively avoided;

[0079] 2. Under the condition of unilateral backfill, calculate various force data of the middle partition wall according to the actual working conditions, so as to be able to specifically strengthen the weak positions of each hole and each layer structure of the middle partition wall, effectively enhance the self-strength of the middle partition wall, reduce deformation, and ensure the smooth progress of the construction;

[0080] 3. Divide the wall into multiple layers, which is convenient for the staff to calculate the wall forces and mark them according to different force conditions, so that the construction personnel can intuitively know the areas on the middle partition wall that need to be reinforced;

[0081] 4. The middle and lower parts of the middle partition wall are subjected to large lateral loads. Pour the holes with concrete of the same grade as the middle partition wall, which effectively increases the strength of the middle and lower parts of the middle partition wall; at the same time, carry out bricklaying mortar plastering treatment on the holes located at the top layer of the middle partition wall. The strength requirement is not high, only the sealing effect needs to be achieved, and the operation is simple and the construction cost is low;

[0082] 5. Conduct full-length post-inserted bars on the tension side of the structure at the hole position under the action of horizontal loads to improve the tensile bearing capacity;

[0083] 6. Apply water-swellable waterstop adhesive on the contact surfaces between each casting layer and the middle partition wall slab to effectively improve the waterproof effect and ensure the sealing performance.

[0084] The above has described the present invention in detail. The purpose is to enable those skilled in this field to understand the content of the present invention and implement it. However, it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for strengthening the middle partition wall under the condition of unilateral filling of a double-hole air shaft. The middle partition wall designed as a vertical load-bearing member is distributed with a plurality of holes. It is characterized in that: The middle partition wall includes a bottom plate, a wall body extending upward from the bottom plate, and a plurality of laminated plates spaced up and down on the wall body. The plurality of laminated plates divide the wall body into the 1st underground layer, the 2nd underground layer... the 5th underground layer sequentially distributed from top to bottom. A plurality of holes are distributed on the wall body of each layer; the filling height is higher than the 1st underground layer; the wall body forms a thickened layer extending up and down from the filling side, and the thickened layer includes a first auxiliary retaining wall located in the 4th underground layer and a second auxiliary retaining wall located in the 5th underground layer. The strengthening method includes the following steps: S1. Increase the bottom restraint range of the middle partition wall Pour backfill materials on both sides of the bottom of the middle partition wall respectively to form a horizontal fixed restraint at the bottom of the middle partition wall. S2. Increase the wall strength at the holes of the middle partition wall Calculate the stress data of the holes on the middle partition wall in the transverse and longitudinal directions according to the most unfavorable working condition of the actual filling, and apply plugging materials into each hole on the middle partition wall below the filling height; implant steel bars around the holes located in the 3rd to 5th underground layers, and pour concrete with the same grade as the wall body into the corresponding holes to form an integral reinforced concrete structure with the wall body. S3. Locally thicken the middle partition wall Divide the middle partition wall into multiple layers from top to bottom, and calculate the stress data of each layer on the middle partition wall in the transverse and longitudinal directions according to the most unfavorable working condition of the actual filling. At the same time, check the bearing capacity and crack width of the mid-span and ends of each layer of the middle partition wall. According to the check results, thicken the parts of the middle partition wall that cannot meet the bearing capacity or normal use requirements. When thickening, set support steel bars fixedly connected to the laminated plates on the filling side of the first auxiliary retaining wall or / and the second auxiliary retaining wall, and set a partition board between the first auxiliary retaining wall or / and the second auxiliary retaining wall.

2. The method for strengthening the middle partition wall under the condition of unilateral filling of a double-hole air shaft according to claim 1, characterized in that: The backfill material is plain concrete, and its backfill height is greater than or equal to 1 m.

3. The method for strengthening the middle partition wall under the condition of unilateral backfilling of a double-hole air shaft according to claim 2, wherein: The backfill layers on the opposite sides of the bottom of the middle partition wall are symmetrically arranged.

4. The method for strengthening the middle partition wall under the condition of single-sided backfilling of a double-hole air shaft according to claim 1, characterized in that: Implant steel bars on the non-filling side of the wall body corresponding to the 3rd to 5th underground layers, and pour concrete after implanting the steel bars.

5. The method for strengthening the middle partition wall under the condition of unilateral backfilling of a double-hole air shaft according to claim 1, wherein: In S2, pour concrete with the same grade as the wall body into the holes in the lower part of the 2nd underground layer, and plug the holes in the upper part of the 2nd underground layer with bricklaying mortar plastering.

6. The method for strengthening the middle partition wall under the condition of unilateral filling of a double-hole air shaft according to claim 1, characterized in that: In the 5th underground layer, a plurality of plain concrete rib plates are arranged on the non-filling side of the wall body, and a plurality of the rib plates are located between the backfill layer and the laminated plate at the top of the 5th underground layer.

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