Construction method of slag pool with retaining wall having large-height-difference buttress columns

Abstract

The application discloses a construction method of a muck pool with a large-height-difference buttress retaining wall, which comprises the following steps: constructing a vertical buttress retaining wall on the structural roof of the open-cut section of the tunnel behind the bored section, wherein the top of the buttress retaining wall is close to the ground, and the two sides of the buttress retaining wall are connected with the surrounding structures on the two sides of the open-cut section of the tunnel; performing waterproof construction on the top surface of the structural roof and the back surface of the buttress retaining wall to form a waterproof structure layer; performing earthwork backfilling in the space surrounded by the surrounding structures on the two sides, the structural roof and the buttress retaining wall to form a backfilling soil layer; constructing a muck pool bottom plate on the top of the backfilling soil layer, and vertically and perpendicularly arranging a buttress side wall on the muck pool bottom plate, wherein the buttress side wall is parallel to the buttress retaining wall, is arranged at intervals, and is connected with the surrounding structures on the two sides of the open-cut section of the tunnel. The construction method of the muck pool not only solves the technical problem of constructing a muck pool behind the tunnel after excavation, but also has a larger capacity than the muck pool constructed on a service road, and does not occupy the service road.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of civil engineering, in particular, to a construction method of a muck pit with a buttress retaining wall of large height difference. BACKGROUND

[0002] There is an interval tunnel engineering between stations, and the interval tunnel construction mainly adopts a shield construction method, and other construction methods are adopted under special requirements, such as a parking line requirement of the interval tunnel, a tunnel excavation method is adopted in the interval of the parking line, a shield method is adopted for the remaining interval, or a tunnel excavation method is adopted for the entire interval.

[0003] The interval tunnel excavation generally sets a station or a temporary vertical shaft, and the tunnel main hole is constructed from a deep foundation pit, due to the limitation of the construction site, most stations and vertical shafts have only one construction access, and the tunnel directly above cannot be stacked, so the muck pit can only be arranged behind the tunnel excavation. There is a parking line in the E-Xiu interval tunnel, and a tunnel excavation method + open excavation method is adopted, and the height difference of the muck pit constructed behind the tunnel excavation is generally 0-4 meters, and due to the tunnel excavation method + open excavation method, the height difference of the muck pit constructed behind the tunnel excavation is 9 meters, and the original design is a 5-meter-high retaining wall, which cannot meet the construction conditions of the muck pit.

[0004] Therefore, it is necessary to provide a buttress retaining wall with large height difference and a muck pit construction method, which can solve the technical problem of the muck pit constructed behind the tunnel excavation and has certain economic benefits. SUMMARY

[0005] The present application provides a construction method of a muck pit with a buttress retaining wall of large height difference to solve the technical problem that the construction method of the existing muck pit cannot meet the construction requirements of the muck pit.

[0006] The technical scheme adopted by the present application is as follows:

[0007] A construction method of a muck pit with a buttress retaining wall of large height difference, comprising the following steps: S10: constructing a buttress retaining wall vertically arranged on the structure top plate of the open excavation section tunnel behind the tunnel excavation section, and the top of the buttress retaining wall is close to the ground and the two sides of the buttress retaining wall are connected with the surrounding structures on both sides of the open excavation section tunnel; S20: performing waterproof construction on the top surface of the structure top plate and the back surface of the buttress retaining wall to form a waterproof structure layer; S30: performing earthwork backfilling in the space surrounded by the surrounding structures on both sides, the structure top plate and the buttress retaining wall to form a backfill soil layer; S40: constructing a muck pit bottom plate on the top of the backfill soil layer, and vertically supporting a buttress side wall on the muck pit bottom plate, and the buttress side wall is arranged in parallel and spaced apart with the buttress retaining wall, and the two sides of the buttress side wall are also connected with the surrounding structures on both sides of the open excavation section tunnel.

[0008] Further, the buttress retaining wall comprises a retaining wall for retaining soil, and a plurality of first buttress columns for reinforcing the retaining wall to support stability; the retaining wall is vertically arranged on the structural roof along the width direction of the open-cut section tunnel, and the two sides of the retaining wall are connected with the enclosure structure respectively; the plurality of first buttress columns are arranged on the wall surface side of the retaining wall and are sequentially and spacedly arranged along the width direction of the retaining wall, and each first buttress column is arranged on the structural roof and connected with the retaining wall on the side surface.

[0009] Further, the construction of the buttress retaining wall comprises the following steps: reinforcing bar binding of the buttress retaining wall is performed on the top of the structural roof; formwork construction is performed on the bound reinforcing bars; and the buttress retaining wall is poured with concrete in batches.

[0010] Further, the bound reinforcing bars of the buttress retaining wall are connected with the reserved bars of the structural roof and the planted bars of the enclosure structure respectively.

[0011] Further, the waterproof structure layer comprises a paint waterproof layer coated on the back surface of the buttress retaining wall and the top surface of the structural roof, a waterproof cloth layer laid on the paint waterproof layer, a concrete waterproof layer arranged in parallel and spacedly with the waterproof cloth layer on the structural roof, a brick wall arranged in parallel and spacedly with the waterproof cloth layer of the buttress retaining wall, a mortar joint filling layer formed by filling the gap between the concrete waterproof layer and the brick wall and the waterproof cloth layer, and a cement mortar sealing layer sealing the top of the brick wall and the mortar joint filling layer; and a bottom layer is laid on the concrete waterproof layer.

[0012] Further, the construction of the waterproof structure layer comprises the following steps: the paint is coated on the top surface of the structural roof to form the paint waterproof layer; the non-woven fabric is laid on the paint waterproof layer of the structural roof to form the waterproof cloth layer; the concrete is poured on the waterproof cloth layer of the structural roof to form the concrete waterproof layer; the paint is coated on the back surface of the buttress retaining wall to form the paint waterproof layer; the brick wall is built on the concrete waterproof layer, and the self-leveling mortar joint filling layer is formed by using the self-leveling mortar joint filling; and the thick polymer cement mortar sealing layer is formed by using the thick polymer cement mortar sealing on the top of the brick wall and the mortar joint filling layer.

[0013] Further, the step S40 specifically comprises the following steps: reinforcing bar binding of the slag pool bottom plate is performed on the top of the backfill soil layer; reinforcing bar binding and formwork construction of the buttress side wall are performed on the bound reinforcing bars of the slag pool bottom plate; and the slag pool bottom plate and the buttress side wall are sequentially poured with concrete.

[0014] Further, the bound reinforcing bars of the slag pool bottom plate are connected with the planted bars of the buttress retaining wall and the enclosure structure respectively; and the bound reinforcing bars of the buttress side wall are connected with the bound reinforcing bars of the slag pool bottom plate and the planted bars of the enclosure structure respectively.

[0015] Further, the buttress column side wall comprises a side wall for retaining soil, and a plurality of second buttress columns for enhancing the support stability of the side wall; the side wall is vertically arranged on the bottom plate layer along the width direction of the open-cut section tunnel, and the two sides of the side wall are connected with the enclosure structure respectively; the plurality of second buttress columns are arranged on the wall surface side of the side wall and are sequentially and spacedly arranged along the width direction of the side wall, and each second buttress column is arranged on the bottom plate layer and connected with the side wall.

[0016] Further, before step S10, the method further comprises the steps of: calculating the section of the buttress column retaining wall, and reinforcing and checking the reinforcement of the buttress column retaining wall.

[0017] The present application has the following advantages:

[0018] The construction method of the muck pit with the buttress column retaining wall with large height difference has the following advantages: on the one hand, the technical problem of constructing a muck pit after tunnel excavation is solved; on the other hand, the capacity of the muck pit is larger than that of a muck pit constructed on a convenient path, and the convenient path is not occupied.

[0019] In addition to the objects, features, and advantages described above, the present application has other objects, features, and advantages. The present application will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which form a part of this application, are intended to provide further understanding of the application and are incorporated herein in their entirety. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0021] Figure 1 is a waterproof construction drawing of the buttress retaining wall in the construction method of the slag pool according to the preferred embodiment of the present application;

[0022] Figure 2 is Figure 1 is a cross-sectional view of the buttress retaining wall;

[0023] Figure 3 is a plan view of the slag pool constructed by using the construction method of the slag pool according to the preferred embodiment of the present application.

[0024] Legend

[0025] 10, structural roof; 20, buttress retaining wall; 21, retaining wall; 22, first buttress; 30, buttress side wall; 31, side wall; 32, second buttress; 40, bottom layer; 42, slag pool bottom; 50, enclosure structure; 60, waterproof structure layer; 61, paint waterproof layer; 62, concrete waterproof layer; 63, brick wall; 64, mortar caulking layer; 65, cement mortar sealing layer. DETAILED DESCRIPTION

[0026] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered below.

[0027] With reference to Figure 1 , the preferred embodiment of the present application provides a construction method of a slag pool with a buttress retaining wall having a large height difference, comprising the following steps:

[0028] S10: constructing a buttress retaining wall 20 vertically arranged on the structural roof 10 of the open-cut section tunnel behind the tunnel of the underground excavation section, with the top close to the ground and the two sides connected to the enclosure structure 50 on both sides of the open-cut section tunnel;

[0029] S20: performing waterproof construction on the top surface of the structural roof 10 and the back surface of the buttress retaining wall 20 to form a waterproof structure layer 60;

[0030] S30: performing earthwork backfilling in the space enclosed by the two sides of the enclosure structure 50, the structural roof 10 and the buttress retaining wall 20 to form a backfill soil layer;

[0031] S40: constructing a slag pool bottom 42 on the top of the backfill soil layer, and a buttress side wall 30 vertically arranged on the slag pool bottom 42 and spaced apart from the buttress retaining wall 20 in parallel, with the two sides also connected to the enclosure structure 50 on both sides of the open-cut section tunnel.

[0032] The construction method of the muck pit with the large-height-difference buttress retaining wall of the present application solves the technical problem of constructing a muck pit after tunnel excavation in two aspects. On the one hand, when a retaining wall is directly designed behind the tunnel excavation, although it can be used to store muck, the height of the retaining wall is generally not more than 5 m due to the height limitation of the existing general retaining wall. When the general retaining wall is used to construct the muck pit, the height of the top of the muck pit from the ground is still high, which is not convenient for the ground excavator to dump the muck in the muck pit, i.e., the efficiency of muck dumping is very low. In the present application, the general retaining wall is modified into a buttress retaining wall 20, which has a higher height, and the elevation of the muck pit is raised by backfilling the earth, so that the ground excavator can smoothly dump the muck in the muck pit, thereby solving the problem of muck dumping efficiency and the technical problem of constructing a muck pit after tunnel excavation. On the other hand, the capacity of the muck pit is larger than that of the muck pit constructed on the service road, and the service road is not occupied. According to the actual construction situation, the area directly above the tunnel excavation and the side of the road cannot be used as a muck pit construction area, and the service road can be used to construct a muck pit. However, due to the fact that the foundation pit of the open excavation section of the tunnel has not been closed, the bearing capacity is low when the retaining wall is used in combination with the surrounding structure outside the foundation pit, so the height of the muck should be generally less than 2 m. The structure of the present application uses the muck pit bottom layer bearing formed by backfilling and pouring to cooperate with the buttress retaining wall 20 and the buttress side wall 30 with high structural strength, so that the height of the muck in the muck pit after tunnel excavation can reach 3 m, thereby improving the bearing capacity of the muck pit and saving construction land, which has high economic benefits. In addition, the construction method of the muck pit of the present application has simple construction steps and high construction efficiency.

[0033] Optionally, as shown in Figure 3 The buttress retaining wall 20 includes a retaining wall 21 for retaining soil, and a plurality of first buttress columns 22 for enhancing the support stability of the retaining wall 21. The retaining wall 21 is vertically arranged on the structural top plate 10 along the width direction of the open excavation section of the tunnel, and the two sides of the retaining wall 21 are connected with the surrounding structure 50. The plurality of first buttress columns 22 are arranged on the wall surface side of the retaining wall 21 and are sequentially and spacedly arranged along the width direction of the retaining wall 21, and each first buttress column 22 is arranged on the structural top plate 10 and connected with the retaining wall 21 on the side. The structure of the buttress retaining wall 20 blocks the backfilling soil through the retaining wall 21, and enhances the stability of the overall structure of the retaining wall 21 through the connection with the surrounding structure 50 on both sides. On the other hand, the stability of the overall structure is further enhanced through the arrangement of the first buttress columns 22, so that the buttress retaining wall 20 can stably support the muck with a height of more than 9 m, thereby meeting the construction requirements.

[0034] Optionally, the construction method of the buttress retaining wall 20 includes the following steps:

[0035] Steel bar binding of buttress retaining wall 20 is carried out on the top of structural roof 10;

[0036] Formwork construction is carried out on the bound steel bars;

[0037] Buttress retaining wall 20 is poured with concrete in batches.

[0038] Specifically, as shown in Figure 2 the reserved steel bars of the buttress retaining wall are reserved on the structural roof 10 behind the tunnel excavation of the underground excavation section, i.e. the structural roof 10 of the open excavation section, and the concrete is poured after the formwork construction of the structural roof is completed to form the structural roof 10. In the step of "carrying out steel bar binding of buttress retaining wall 20 on the top of structural roof 10", the distribution steel bars of the buttress retaining wall 20 must be connected with the reserved steel bars in the structural roof and the planted steel bars of the enclosure structure 50 respectively, the planted steel bars of the enclosure structure 50 have a depth of 22d and are not less than 300mm, the diameter is greater than 20, the steel bars require to be connected by straight thread sleeve, and the joints are staggered by at least 1m. In the step of "carrying out formwork construction on the bound steel bars", it includes: ① retaining wall 21 construction, 400mm thick retaining wall small beam: 50(wide)*70(high) square wood, interval 250mm; main beam: double-pinned φ48*3mm(Q235), interval 500mm; formwork: 15mm composite formwork; tensioning screw rod: M14, interval 500*500mm. ② 1500mm*800mm first buttress 22 construction, 800mm short side adopts two vertical main beams, 1100mm long side adopts three vertical main beams, the transverse interval of the tensioning screw rod is consistent with the interval of the main beam, the vertical interval is 500mm, the rest of the parameters are the same as those of the 400mm thick retaining wall 21, and during construction, the first step is to assemble the formwork and the square wood; the second step is to hoist the assembled formwork and square wood to the position of the buttress retaining wall steel bars, install the formwork, and install the double-pinned steel pipe and the tensioning screw rod; the third step is to set a throw support every two meters along the width of the buttress retaining wall, set a throw support every 3 meters along the height of the buttress retaining wall, and set the supports on the south side.

[0039] Alternatively, as shown in Figure 1As shown, the waterproof structure layer 60 comprises a paint waterproof layer 61 painted on the back of the buttress retaining wall 20 and the top surface of the structural top plate 10, a waterproof cloth layer laid on the paint waterproof layer 61, a concrete waterproof layer 62 arranged in parallel and spaced apart with the waterproof cloth layer on the structural top plate 10, a brick wall 63 arranged in parallel and spaced apart with the waterproof cloth layer of the buttress retaining wall 20, a mortar joint filling layer 64 formed by filling the gaps between the concrete waterproof layer 62 and the waterproof cloth layer and the brick wall 63, and a cement mortar sealing layer 65 sealing the top of the brick wall 63 and the mortar joint filling layer 64. The bottom plate layer 40 is laid on the concrete waterproof layer 62. The design of the waterproof structure layer 60 can effectively prevent the seepage of mud and water in the spoil pit, thereby stabilizing the structure of the spoil pit.

[0040] As shown in the optional scheme, Figure 1 The construction of the waterproof structure layer 60 comprises the following steps:

[0041] Painting paint on the top surface of the structural top plate 10 to form a paint waterproof layer 61: after cleaning the surface of the structural top plate 10, paint is applied in three coats, and the directions of the upper and lower two coats should be perpendicular to each other, and the next coat can be applied only after the previous coat is dry. The minimum thickness of the paint waterproof layer 61 is 2.5 mm, and the amount used is greater than 3.8 kg / m 2 The paint waterproof layer 61 is overlapped by 200 mm between the sections.

[0042] Laying non-woven fabric on the paint waterproof layer 61 of the structural top plate 10 to form a waterproof cloth layer: laying a 100 g / m 2 non-woven fabric isolation layer;

[0043] Pouring concrete on the waterproof cloth layer of the structural top plate 10 to form a concrete waterproof layer 62: a 70 mm thick C20 fine stone concrete is used to form the concrete waterproof layer 62.

[0044] Painting paint on the back of the buttress retaining wall 20 to form a paint waterproof layer 61, the operation steps of which are the same as those of painting paint on the top surface of the structural top plate 10.

[0045] Building a brick wall 63 on the concrete waterproof layer 62, and forming a mortar joint filling layer 64 by using self-leveling mortar joint filling.

[0046] Forming a cement mortar sealing layer 65 by using thick polymer cement mortar sealing on the top of the sealed brick wall 63 and the mortar joint filling layer 64.

[0047] The specific construction steps of the waterproof structure layer 60 of the present application are simple in the construction process, low in cost, and good in waterproof effect, which can effectively meet the construction requirements.

[0048] Optionally, in step S30, the earthwork is backfilled to a height of 3m from the ground, so as to define the bottom of the slag pool at a height of nearly 3m from the ground, meeting the requirement of using ground excavating trucks to discard the slag soil outside, and in actual operation, the compaction degree experiment needs to be done every 30cm to make the earthwork meet the support requirement.

[0049] Optionally, as shown in Figure 2 step S40 specifically includes the following steps:

[0050] The reinforcement binding of the slag pool bottom plate 42 is carried out on the top of the backfill soil layer: the bound reinforcement of the slag pool bottom plate 42 is connected with the wall column retaining wall 20 and the embedded reinforcement of the enclosure structure 50 respectively, and the embedded depth of the embedded reinforcement of the enclosure structure 50 is 22d and is not less than 300mm;

[0051] The reinforcement binding and formwork construction of the wall column side wall 30 are carried out on the bound reinforcement of the slag pool bottom plate 42: the bound reinforcement of the wall column side wall 30 is connected with the bound reinforcement of the slag pool bottom plate 42 and the embedded reinforcement of the enclosure structure 50 respectively, and the reinforcement binding and formwork construction of the wall column side wall 30 are basically the same as those of the wall column retaining wall 20;

[0052] The slag pool bottom plate 42 and the wall column side wall 30 are successively poured with concrete: C30 concrete is used, and the pouring is carried out twice, the first time for pouring the slag pool bottom plate 42, and after final setting, the wall column side wall 30 is poured.

[0053] Optionally, as shown in Figure 3 the wall column side wall 30 includes a side wall 31 for retaining soil and a plurality of second wall columns 32 for enhancing the support stability of the side wall 31; the side wall 31 is vertically arranged on the bottom plate layer 40 along the width direction of the open-cut section tunnel, and the two sides of the side wall 31 are connected with the enclosure structure 50 respectively; the plurality of second wall columns 32 are arranged on the wall surface side of the side wall 31 and are successively and spacedly arranged along the width direction of the side wall 31, and each second wall column 32 is arranged on the bottom plate layer 40 and connected with the side wall 31 on the side. Through the arrangement of the side wall 31 and the second wall columns 32, the side wall 31 can block the backfill soil, and the connection with the enclosure structure 50 on both sides can enhance the stability of the overall structure of the side wall 31, and on the other hand, the arrangement of the second wall columns 32 can further enhance the stability of the overall structure, so that the wall column side wall 30 can stably support the slag soil, thereby meeting the construction requirement.

[0054] Optionally, before step S10, it further includes the step of:

[0055] The section of the wall column retaining wall 20 is calculated, and the wall column retaining wall 20 is reinforced and the reinforcement is checked, so that the constructed wall column retaining wall 20 meets the bearing requirement, and the overall structure of the slag pool is stable and reliable.

[0056] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A construction method for a spoil heap with retaining walls featuring buttress columns with a large elevation difference, characterized in that, Includes the following steps: S10: Construct a vertical buttress retaining wall (20) on the top slab (10) of the open-cut section tunnel behind the cut-and-cover section tunnel. The buttress retaining wall (20) is set up with its top close to the ground and its sides connected to the retaining structures (50) on both sides of the open-cut section tunnel. S20: Waterproofing construction is carried out on the top surface of the structural top slab (10) and the back wall of the buttress retaining wall (20) to form a waterproof structural layer (60); S30: Backfilling is carried out in the space enclosed by the retaining structures (50) on both sides, the top slab (10) of the structure and the retaining wall (20) of the buttress column to form a backfill soil layer; S40: Construct a slag pit bottom slab (42) on top of the backfill soil layer, and a buttress sidewall (30) that is vertically supported on the slag pit bottom slab (42) and is parallel to the buttress retaining wall (20) and is connected to the retaining structure (50) on both sides of the open-cut section tunnel respectively. The retaining wall (20) includes a retaining wall (21) for retaining soil and multiple first retaining columns (22) for enhancing the support stability of the retaining wall (21); the retaining wall (21) is vertically supported on the top slab (10) of the structure along the width direction of the open-cut section of the tunnel, and the two sides of the retaining wall (21) are respectively connected to the retaining structure (50); the multiple first retaining columns (22) are located on the wall side of the retaining wall (21), and are arranged sequentially at intervals along the width direction of the retaining wall (21), and each first retaining column (22) is supported on the top slab (10) of the structure and connected to the retaining wall (21) on the side; The construction of the buttress retaining wall (20) specifically includes the following steps: the steel bars of the buttress retaining wall (20) are tied at the top of the top slab (10) of the structure; the formwork is constructed on the tied steel bars; the buttress retaining wall (20) is poured in stages with concrete; wherein the tied steel bars of the buttress retaining wall (20) are connected to the reserved steel bars of the top slab of the structure and the anchoring steel bars of the retaining structure (50) respectively.

2. The construction method of the slag pit with buttress retaining wall with large elevation difference according to claim 1, characterized in that, The waterproof structural layer (60) includes a coating waterproof layer (61) applied to the back of the buttress retaining wall (20) and the top surface of the structural top slab (10), a waterproof cloth layer laid on the coating waterproof layer (61), a concrete waterproof layer (62) arranged parallel and spaced with the waterproof cloth layer on the structural top slab (10), a brick wall (63) arranged parallel and spaced with the waterproof cloth layer of the buttress retaining wall (20), a mortar grouting layer (64) filling the gap between the concrete waterproof layer (62) and the brick wall (63) and the waterproof cloth layer, and a cement mortar sealing layer (65) sealing the top of the brick wall (63) and the mortar grouting layer (64). The base slab (40) is laid on the concrete waterproof layer (62).

3. The construction method of the slag pit with buttress retaining wall with large elevation difference according to claim 2, characterized in that, The construction of the waterproof structural layer (60) specifically includes the following steps: A waterproof coating layer (61) is formed by applying a coating to the top surface of the structural top slab (10); A non-woven fabric is laid on the waterproof coating layer (61) of the structural top slab (10) to form a waterproof fabric layer; Concrete is poured on the waterproof fabric layer of the top slab (10) to form a concrete waterproof layer (62); A coating is applied to the back of the buttress retaining wall (20) to form a waterproof coating layer (61); A brick wall (63) is built on the concrete waterproof layer (62), and a mortar grouting layer (64) is formed by grouting the joints with self-leveling mortar. A cement mortar sealing layer (65) is formed on top of the sealed brick wall (63) and the mortar grouting layer (64).

4. The construction method of the slag pit with buttress retaining wall with large elevation difference according to claim 1, characterized in that, Step S40 specifically includes the following steps: Reinforcing bars are tied to the bottom slab (42) of the slag pit at the top of the backfill soil layer; The reinforcement binding and formwork construction of the buttress column sidewall (30) are carried out on the tied reinforcement of the bottom plate (42) of the slag pit; The bottom slab (42) of the slag discharge pit and the side walls (30) of the buttress columns were poured in sequence using concrete.

5. The construction method of the slag pit with buttress retaining wall with large elevation difference according to claim 4, characterized in that, The reinforcing bars of the bottom slag pit (42) are connected to the reinforcing bars of the buttress column retaining wall (20) and the retaining structure (50) respectively; The reinforcing bars of the buttress sidewall (30) are connected to the reinforcing bars of the slag pit bottom slab (42) and the anchor bars of the retaining structure (50).

6. The construction method of the slag pit with buttress retaining wall with large elevation difference according to claim 4, characterized in that, The buttress sidewall (30) includes a sidewall (31) for retaining soil and multiple second buttresses (32) for enhancing the support stability of the sidewall (31); The sidewall (31) is vertically supported on the bottom slab (40) along the width direction of the open-cut section of the tunnel, and the two sides of the sidewall (31) are connected to the retaining structure (50) respectively. Multiple second buttress columns (32) are located on the wall side of the side wall (31) and are arranged at intervals along the width direction of the side wall (31). Each second buttress column (32) is supported on the bottom slab layer (40) and connected to the side wall (31) on the side.

7. The construction method of the slag pit with buttress retaining wall with large elevation difference according to claim 1, characterized in that, Before proceeding to step S10, the following steps are also included: The cross section of the buttress retaining wall (20) is calculated, and the reinforcement and reinforcement verification of the buttress retaining wall (20) are carried out.

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