Fabricated reverse and forward combined steel-concrete underground structure and reverse and forward combined construction method

Abstract

The invention discloses a fabricated reverse and forward combined steel-concrete underground structure and a reverse and forward combined construction method. The fabricated reverse and forward combined steel-concrete underground structure comprises a foundation pit support structure, a cast-in-place concrete bottom plate, stand columns, middle longitudinal beams, top longitudinal beams, a structural wall body, a structural plate body and a water stop structure. The structure is divided into a reverse operation part and a forward operation part, the reverse operation part and the forward operation part are alternately arranged, the forward operation part is formed behind the reverse operation part, the constructed structure of the reverse operation part also serves as an inner support of the foundation pit, and the space to be constructed between the constructed structures of the reverse operation part and the space to be constructed of the forward operation part also serves as a dynamic unearthing feeding port. According to the method, the reverse construction part constructed firstly replaces a foundation pit inner support, inner support construction is not needed any more, and the working procedures are reduced. And a construction vacancy is reserved in the unconstructed sequential construction part to serve as a dynamic construction operation reserved opening. According to the method, the entity quality of an engineering structure is guaranteed, the construction efficiency of a reverse construction method is improved, and the use, erection and disassembly cost of a horizontal and vertical supporting system of a sequential construction method is reduced.

Description

Technical Field

[0001] The present invention relates to the field of urban underground structure construction, and particularly to an assembled steel-concrete underground structure with combined top-down and bottom-up construction and a construction method thereof with combined top-down and bottom-up construction. Background Art

[0002] With the continuous improvement of the urbanization level, the problem of urban land use has become increasingly prominent, and the development and utilization of urban underground space has become one of the effective ways to solve the big city diseases. Generally, for urban underground structures, after the construction of the foundation pit retaining structure is completed, in-situ casting is adopted. The required number of laborers, types of work, and turnover materials are numerous, the on-site working conditions are poor, the construction period is long, the amount of construction waste is large, and it is difficult to control the quality of the in-situ concrete. In recent years, due to the advantages of fast construction speed, little influence by climatic conditions, and labor saving of prefabricated buildings, they have gradually been applied to the construction of underground stations.

[0003] Whether it is an in-situ underground structure or a prefabricated underground structure, its construction methods include the open cut method and the top-down method. The top-down method is further divided into the top-down construction method, the top-down and bottom-up construction method, and the semi-top-down and bottom-up construction method. The problems existing in each construction method and underground structure are as follows: Open cut method: It is necessary to set 3 - 5 internal supports, and the support cost is relatively high with more processes; the single-layer excavation - support cycle is 7 - 10 days, and the total construction period of the deep foundation pit is relatively long; the support system occupies most of the working space, and the mechanical construction efficiency is relatively low.

[0004] Overall for the top-down method: It is necessary to separately design several operation soil outlets according to the construction conditions, and the soil outlet efficiency is relatively low; Top-down construction method: It is necessary to set temporary horizontal and vertical internal supports, and there are more processes; it is necessary to construct the temporary top cover first, resulting in repeated project quantities.

[0005] Top-down and bottom-up construction method: When casting the in-situ structure, it is necessary to repair the horizontal construction joint generated by the self-weight of the later-constructed lower-layer concrete between the upper and lower in-situ structures in the later stage; the construction convenience is poor.

[0006] Semi-top-down and bottom-up construction method: It is necessary to set temporary horizontal and vertical internal supports, and there are more processes.

[0007] In-situ underground structure: The required number of laborers, types of work, and turnover materials are numerous, the on-site working conditions are poor, the overall stiffness of the structure needs to wait until the structure reaches the design value, the construction period is long, the amount of construction waste is large, and it is difficult to control the quality of the in-situ concrete.

[0008] Prefabricated underground structure: It is not a complete prefabrication, and the joints of the underground structure still need to be cast in-situ, and the construction is cumbersome. Summary of the Invention

[0009] The object of the present invention is to provide a prefabricated steel-concrete underground structure with combined top-down and bottom-up construction and a construction method with combined top-down and bottom-up construction, aiming to solve the technical problems existing in the existing underground structures and construction methods, such as construction joints generated in the cast-in-place structure, long construction period, and difficult control of concrete quality; the joints of the underground prefabricated structure still need to be constructed by cast-in-place; the excavation method requires a separately arranged soil outlet with low soil excavation efficiency; and a separately arranged internal support process is required with many processes and low construction efficiency.

[0010] To achieve the above object, the present invention adopts the following technical solutions: A prefabricated steel-concrete underground structure with combined top-down and bottom-up construction, comprising: A foundation pit retaining structure, including a diaphragm wall and a capping beam at its top, both of which are steel, precast or cast-in-place structures; A cast-in-place concrete bottom slab; A prefabricated concrete underground main structure, comprising: A main framework, including concrete-filled steel tubular columns in the longitudinal middle, a middle longitudinal beam made of steel structure connecting the middle parts of the columns, and a top longitudinal beam made of steel structure connecting the tops of the columns; A structural wall surrounding the main framework along the inner wall of the diaphragm wall, including a lower layer wall and an upper layer wall with precast corbels on the bottom inner wall, the bottom of the lower layer wall is connected to the bottom slab, and the upper layer wall and the lower layer wall are fixedly connected in a vertically aligned manner; A structural slab, including a middle slab fixed on the precast corbels on the wall and the top surface of the middle longitudinal beam, and a top slab fixed on the top surfaces of the upper layer wall, the capping beam and the top longitudinal beam; A water stop structure, including a grouting water stop layer between the structural wall and the diaphragm wall, a waterproof layer on the upper side of the top slab, and water stop strips at the joints of each component; The structure is divided into a top-down part and a bottom-up part, the two parts are arranged alternately and the bottom-up part is formed after the top-down part, the constructed structure of the top-down part also serves as an internal support in the foundation pit, and the space between the constructed structures of the top-down part and the space to be constructed in the bottom-up part also serve as dynamic soil excavation and material feeding ports; According to the construction time, the top longitudinal beam includes a top-down top beam and a bottom-up top beam, the structural wall includes a top-down wall and a bottom-up wall, the middle slab includes a top-down middle slab and a bottom-up middle slab, and the top slab includes a top-down top slab and a bottom-up top slab; The top-down part includes columns and a middle longitudinal beam, and also includes a top-down top beam, a top-down wall, a top-down middle slab and a top-down top slab arranged horizontally corresponding to each other in the foundation pit, and the bottom-up part includes a bottom-up top beam, a bottom-up wall, a bottom-up middle slab and a bottom-up top slab arranged horizontally corresponding to each other in the foundation pit.

[0011] A flange plate for supporting the middle longitudinal beam is fixedly sleeved on the column, a middle beam groove for clamping with the column is provided at the end face of each middle longitudinal beam, a flange plate connection hole is opened on the flange plate, a middle beam end connection vertical through hole corresponding to the flange plate connection hole is opened around the edge of the middle beam groove, and the flange plate connection hole and the middle beam end connection vertical through hole are anchored by bolts.

[0012] A middle plate groove for clamping the column is provided at the connection position between the middle plate and the column, and the remaining parts of adjacent middle plates are butted against each other. The precast corbel on the wall is a steel angle member with a vertical plate, a horizontal plate and a stiffening plate; the vertical plate is anchored to the upper wall by bolts. Middle plate connection side through holes are opened at the positions of the middle plate corresponding to the corbel bolt holes of the horizontal plate, and middle plate connection middle through holes are opened at the positions of the middle plate corresponding to the middle beam body connection vertical through holes of the middle longitudinal beam. The middle plate connection side through holes and the corbel bolt holes, and the middle plate connection middle through holes and the middle beam body connection vertical through holes are all anchored by bolts.

[0013] The reverse construction top beam is fixedly connected to the column. A column blind slot for inserting the top of the column is provided at the bottom of the reverse construction top beam. Beam-column connection bolt holes communicating with the top of the column blind slot are opened at the ends of the reverse construction top beam. Column bolt blind holes corresponding to the beam-column connection bolt holes are opened on the top surface of the column. The column bolt blind holes and the beam-column connection bolt holes are anchored by bolts.

[0014] The forward construction top beam is fixedly connected between adjacent reverse construction top beams, and the cross-sections of the reverse construction top beam and the forward construction top beam are the same; the reverse construction top beam includes a reverse construction top beam main body at the bottom and a reverse construction top beam roof plate at the top. Blind bolt holes under the top beam are opened at the part where the reverse construction top beam main body extends beyond the reverse construction top beam roof plate at the longitudinal connection end; the forward construction top beam includes a forward construction top beam main body at the bottom and a forward construction top beam roof plate at the top. Upper bolt through holes corresponding to the blind bolt holes under the top beam are opened at the part where the forward construction top beam roof plate extends beyond the forward construction top beam main body at the longitudinal connection end; the longitudinal connection ends of the reverse construction top beam and the forward construction top beam are butted against each other, and the extended part of the forward construction top beam roof plate is placed on the extended top surface of the reverse construction top beam main body. The blind bolt holes under the top beam and the upper bolt through holes are anchored by bolts.

[0015] The cross-sections of the reverse construction top beam main body and the forward construction top beam main body are both T-shaped beams, including a beam flat plate and a beam web. The column blind slot is arranged in the beam web, and the blind bolt holes under the top beam are arranged in the beam flat plate. The reverse construction top beam roof plate and the forward construction top beam roof plate are both provided with row-by-row beam-plate connection bolt blind holes, and the hole depth of the beam-plate connection bolt blind holes is greater than the thickness of the reverse construction top beam roof plate or the forward construction top beam roof plate and extends into the beam flat plate.

[0016] A row of wall bolt blind holes are provided at the vertical connection ends of the upper wall and the lower wall. A rectangular operation opening communicating with the wall bolt blind holes is opened on the inner side wall. The upper and lower adjacent wall bolt blind holes are anchored by bolts. The wall bolt blind holes of the lower wall and the bottom plate, and the wall bolt blind holes of the upper wall and the top plate are anchored by bolts; the edges of horizontally adjacent structural walls are mutually lapped and engaged by half-thickness lapping plates, and the wall lapping horizontal through holes opened on the half-thickness lapping plates are aligned and anchored by bolts.

[0017] The top surface of the capping beam is provided with capping beam connection blind holes, and the top plate is provided with a top plate connection middle through hole, a top plate connection wall through hole, and a top plate connection capping beam through hole corresponding to the beam - plate connection bolt blind hole of the top beam, the wall bolt blind hole of the upper - layer wall, and the capping beam connection blind hole respectively; the top plate connection middle through hole and the beam - plate connection bolt blind hole, the top plate connection wall through hole and the capping beam connection blind hole, the top plate connection wall through hole and the wall bolt blind hole are all anchored by bolts; the bottom of the top plate is provided with a longitudinal top - beam connection groove, the groove depth and width of which are adapted to the thickness and width of the top - beam top plate in top - down construction and the top - beam top plate in bottom - up construction, and the top - beam connection groove is clamped to the top surface of the top beam.

[0018] A construction method for the combination of top - down and bottom - up construction of an assembled steel - concrete underground structure, the construction steps are as follows: Step 1: After measuring and setting out the lines, excavate the guide - wall trench and construct the guide wall; use a grooving machine to excavate the trench of the foundation - pit retaining structure under mud - slurry support and clean the bottom; construct the diaphragm wall in the trench. Start constructing the top - down part: Step 2: Synchronously construct the columns with the diaphragm wall. After measuring and setting out the lines, use a hole - forming machine to excavate the column holes under mud - slurry support and clean the bottom; construct the columns in the holes. Step 3: Excavate the soil downward in the area enclosed by the diaphragm wall to the bottom - elevation position of the top plate and the top longitudinal beam. Step 4: Construct the capping beam and the top - down top beam, and fixedly connect the top - down top beam with the columns. Step 5: Construct the top - down top plate, and fixedly connect the top - down top plate with the capping beam and the top - down top beam. Step 6: Construct the upper - layer steel - wall installation brackets and hydraulic jacks: Continue to excavate the soil downward to the bottom - elevation position of the upper - layer steel - wall installation brackets. Anchor the upper - layer steel - wall installation brackets to the diaphragm wall. The upper - layer steel - wall installation brackets are provided with hydraulic jacks, and each group of upper - layer steel - wall installation brackets and hydraulic jacks are arranged at the bottom of the structure wall to be installed. Step 7: Construct the upper - layer wall of the top - down wall, and fixedly connect the upper - layer wall of the top - down wall with the top - down top plate and the adjacent upper - layer wall of the top - down wall; among them, the upper - layer wall is assisted in installation by the upper - layer steel - wall installation brackets and hydraulic jacks. Step 8: Construct the middle longitudinal beam, and fixedly connect the middle longitudinal beam with the middle columns. Step 9: Construct the top - down middle plate, and fixedly connect the top - down middle plate with the upper - layer wall of the top - down wall and the middle longitudinal beam. Step 10: Construct the lower - layer steel - wall installation brackets and hydraulic jacks: Continue to excavate the soil downward to the bottom - elevation position of the lower - layer steel - wall installation brackets, and install the lower - layer steel - wall installation brackets and hydraulic jacks in the same way as in Step 6. Step 11: Construct the lower - layer wall of the top - down wall, and fixedly connect the lower - layer wall of the top - down wall with the upper - layer wall of the top - down wall and the adjacent lower - layer wall of the top - down wall. Step Twelve, construct the floor slab, fixedly connect the lower layer wall of the reverse construction wall with the floor slab, and wait for the floor slab to reach the designed strength; Start the construction of the forward construction part: Step Thirteen, construct the lower layer wall of the forward construction wall, and fixedly connect the lower layer wall of the forward construction wall with the floor slab and the lower layer wall adjacent to the forward construction wall; Step Fourteen, construct the upper layer wall of the forward construction wall, and fixedly connect the upper layer wall of the forward construction wall with the lower layer wall of the forward construction wall and the upper layer wall adjacent to the forward construction wall; Step Fifteen, construct the forward construction middle slab, and fixedly connect the forward construction middle slab with the upper layer wall of the forward construction wall and the middle longitudinal beam; the forward construction middle slab is also fixedly connected with the adjacent reverse construction middle slab; Step Sixteen, construct the forward construction top beam, and fixedly connect the forward construction top beam with the adjacent reverse construction top beam; Step Seventeen, construct the forward construction top slab, and fixedly connect the forward construction top slab with the forward construction top beam, the upper layer wall and the capping beam; the forward construction top slab is also fixedly connected with the adjacent reverse construction top slab; Step Eighteen, after the construction of the prefabricated concrete underground main structure and the floor slab is completed, carry out filling grouting between the outer side of the wall structure and the inner side of the diaphragm wall to form a grouting water-stop layer; Step Nineteen, construct a waterproof layer above the top slab; Step Twenty, backfill the soil above the top slab and restore the original ground surface.

[0019] The reverse-forward construction method of the prefabricated reverse-forward combined steel-concrete underground structure is specifically as follows: In Step Four, the specific construction of the reverse construction top beam is as follows: hoist the reverse construction top beam piece by piece, insert the top of the column into the column blind socket, align the column bolt blind hole with the beam-column connection bolt hole and anchor with bolts; In Step Five, the specific construction of the reverse construction top slab is as follows: hoist the reverse construction top slab piece by piece, align the through hole in the top slab connection with the blind bolt hole for beam-slab connection of the reverse construction top beam, align the through hole in the top slab connection wall with the blind connection hole of the capping beam, and anchor both with bolts; In Step Seven, the specific construction of the upper layer wall of the reverse construction wall is as follows: hoist the upper layer wall piece by piece and place it on the steel wall installation bracket, start the hydraulic jack to make the top surface of the upper layer wall closely adhere to the bottom surface of the top slab; align the through hole in the top slab connection wall with the bolt blind hole of the wall and anchor with bolts, make the adjacent upper layer walls bite and overlap with each other and anchor with bolts, and then remove the steel wall installation bracket and the hydraulic jack; In Step Eight, the specific construction of the middle longitudinal beam is as follows: hoist the middle longitudinal beam one by one, place the middle longitudinal beam on the flange plate, align the connection hole of the flange plate with the vertical through hole at the end of the middle beam and anchor with bolts; In Step 9, the specific construction of the inverted middle slab is as follows: hoist the inverted middle slab piece by piece and place the two ends on the precast corbels on the upper-layer walls in Step 7 and the middle longitudinal beam respectively. Align the through holes on the connecting edges of the middle slab with the bolt holes of the corbels, and align the through holes in the middle of the middle slab with the vertical through holes connecting the middle beam body. All are anchored by bolts. In Step 11, the specific construction of the lower-layer wall of the inverted wall is as follows: hoist the lower-layer wall piece by piece and place it on the steel wall installation corbels. Start the hydraulic jack to make the top surface of the lower-layer wall closely fit with the bottom surface of the upper-layer wall. Align the blind bolt holes of the adjacent upper and lower walls and anchor them with bolts. Interlock and lap the adjacent lower-layer walls and anchor them with bolts. Then remove the steel wall installation corbels and the hydraulic jack. In Step 12, reserve floor slab bolt holes in the floor slab casting for connection with the blind bolt holes at the bottom of the lower-layer wall of the forward construction wall. In Step 13, the specific construction of the lower-layer wall of the forward construction wall is as follows: hoist the lower-layer wall piece by piece. Anchor the blind bolt holes at the bottom of the lower-layer wall with the floor slab bolt holes in Step 12. Interlock and lap the adjacent lower-layer walls and anchor them with bolts. In Step 14, the specific construction of the upper-layer wall of the forward construction wall is as follows: hoist the upper-layer wall piece by piece. Make the bottom surface of the upper-layer wall closely fit with the top surface of the lower-layer wall. Interlock and lap the adjacent upper-layer walls and anchor them with bolts. In Step 15, the specific construction of the forward construction middle slab is as follows: hoist the forward construction middle slab piece by piece and place the two ends on the precast corbels on the upper-layer walls in Step 14 and the middle longitudinal beam respectively for fixed connection. Among them, align the through holes on the connecting edges of the middle slab with the bolt holes of the corbels, and align the through holes in the middle of the middle slab with the vertical through holes connecting the middle beam body. All are anchored by bolts. In Step 16, the specific construction of the forward construction top beam is as follows: hoist the forward construction top beam one by one, and make the end faces of the connecting ends of the forward construction top beam and the inverted top beam fit. Align the blind bolt holes under the top beam with the through bolt holes on the top beam and anchor them with bolts. In Step 17, the specific construction of the forward construction roof slab is as follows: hoist the forward construction roof slab piece by piece. Align the through holes in the middle for connection with the blind bolt holes of the beam-slab connection of the forward construction top beam, and align the through holes connecting the wall of the roof slab with the blind holes connecting the crown beam. All are anchored by bolts. Align the through holes connecting the wall of the roof slab with the blind bolt holes of the wall and anchor them with bolts.

[0020] Compared with the prior art, the present invention has the following features and beneficial effects: All components of the steel-concrete underground structure of the present invention are bolt-connected to form a dry connection of a fully prefabricated underground structure, solving the disadvantages of forming horizontal construction joints in cast-in-place underground structures and still requiring cast-in-place at the joints in prefabricated underground structures.

[0021] The present invention ingeniously segments each component, enabling it to be divided into a reverse construction part and a forward construction part during construction. The previously constructed reverse construction part replaces the internal support in the foundation pit, eliminating the need for internal support construction and reducing the construction process. Meanwhile, the unconstructed forward construction part, especially the reserved construction spaces for the forward wall, forward roof, forward top beam, and forward middle slab, serves as dynamic construction operation reserved openings for earth (stone) excavation and component entry during construction. Subsequently, the forward construction part is constructed to complete the overall underground structure. The present invention ensures the quality of the engineering structure entity, improves the construction efficiency of the reverse construction method, and reduces the usage, erection, and demolition costs of the horizontal and vertical support systems in the forward construction method. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described in detail below with reference to the accompanying drawings.

[0023] Figure 1 It is an exploded view of the structure completed in Step 4 of the present invention.

[0024] Figure 2 It is a schematic structural diagram of the reverse top beam of the present invention.

[0025] Figure 3 It is Figure 2 The top view structural schematic diagram of

[0026] Figure 4 It is Figure 2 The bottom view structural schematic diagram of

[0027] Figure 5 It is an exploded view of the structure completed in Step 5 of the present invention.

[0028] Figure 6 It is a schematic structural diagram of the reverse roof and the forward roof of the present invention.

[0029] Figure 7 It is an exploded view of the structure completed in Step 7 of the present invention.

[0030] Figure 8 It is a schematic structural diagram of the upper wall in the reverse wall of the present invention.

[0031] Figure 9 It is Figure 7 The top view structural schematic diagram of

[0032] Figure 10 It is Figure 9 The sectional structural schematic diagram of A - A in

[0033] Figure 11 It is a schematic structural diagram of the upper flange of the column of the present invention.

[0034] Figure 12 It is an exploded view of the structure completed in Step 8 of the present invention.

[0035] Figure 13 It is a schematic structural diagram of the longitudinal beam in the present invention.

[0036] Figure 14 It is an exploded structural diagram completed in Step 9 of the construction of the present invention.

[0037] Figure 15 It is a schematic structural diagram of the middle slab of the inverted slab in the present invention.

[0038] Figure 16 It is a schematic structural diagram of the middle-edge slab of the inverted slab in the present invention.

[0039] Figure 17 It is an exploded structural diagram completed in Step 10 of the construction of the present invention.

[0040] Figure 18 It is a schematic structural diagram of the lower wall in the inverted wall of the present invention.

[0041] Figure 19 It is Figure 17 a top view structural diagram of.

[0042] Figure 20 It is Figure 19 a schematic structural diagram of the B-B section in.

[0043] Figure 21 It is an exploded structural diagram completed in Step 13 of the construction of the present invention.

[0044] Figure 22 It is a schematic structural diagram of the upper wall in the forward-constructed wall of the present invention.

[0045] Figure 23 It is an exploded structural diagram completed in Step 19 of the construction of the present invention.

[0046] Figure 24 It is a schematic structural diagram of the forward-constructed slab of the present invention.

[0047] Figure 25 It is a schematic structural diagram of the forward-constructed top beam of the present invention.

[0048] Figure 26 It is Figure 25 a top view structural diagram of.

[0049] Figure 27 It is Figure 23 a top view structural diagram of.

[0050] Figure 28 It is Figure 27 a schematic structural diagram of the C-C section in.

[0051] Figure 29 It is a schematic diagram of the component waterproof layer of the present invention.

[0052] Reference numerals: 1 - diaphragm wall, 2 - column, 21 - flange plate, 211 - flange plate connection hole, 22 - blind hole of column bolt, 3 - top slab of top-down construction, 4 - top beam of top-down construction, 41 - blind slot for column in top beam, 42 - bolt hole for beam-column connection, 43 - main body of top beam of top-down construction, 44 - top slab of top beam of top-down construction, 45 - blind hole of bolt under top beam, 5 - top beam of bottom-up construction, 51 - main body of top beam of bottom-up construction, 52 - top slab of top beam of bottom-up construction, 53 - through hole of bolt on top beam, 6 - upper wall, 61 - precast corbel on wall, 611 - vertical plate, 612 - horizontal plate, 613 - bolt hole of corbel, 614 - stiffening plate, 7 - lower wall, 8 - middle slab of top-down construction, 81 - middle side slab, 82 - middle slab, 9 - middle slab of bottom-up construction, 10 - top slab of bottom-up construction, 11 - middle longitudinal beam, 111 - groove of middle beam, 112 - vertical through hole for end connection of middle beam, 113 - vertical through hole for body connection of middle beam, 12 - bottom slab, 13 - side through hole for middle slab connection, 14 - middle through hole for middle slab connection, 15 - capping beam, 151 - blind hole for capping beam connection, 16 - blind hole of bolt for beam-slab connection, 17 - middle through hole for top slab connection, 18 - grouting water-stop layer, 19 - waterproof layer, 20 - dynamic soil outlet and feeding port, 23 - groove of middle slab, 24 - flat plate of beam, 25 - web of beam, 26 - blind hole of wall bolt, 27 - rectangular operation opening, 28 - water-stop strip, 29 - connection groove of top beam, 30 - steel wall installation corbel, 31 - hydraulic jack, 40 - half-thickness lap plate, 46 - horizontal through hole for wall lap, 47 - through hole for top slab-wall connection, 48 - through hole for top slab-capping beam connection. Detailed implementation mode

[0053] See the embodiment Figure 1 - 29 As shown in the figure, an assembled top-down and bottom-up steel-concrete underground structure includes a foundation pit retaining structure, a bottom slab 12 of cast-in-place concrete, an assembled concrete underground main structure, and a water-stop structure.

[0054] The foundation pit retaining structure includes a diaphragm wall 1 and a capping beam 15 arranged at the top of the diaphragm wall 1. The diaphragm wall 1 and the capping beam 15 are made of steel, precast, or cast-in-place structures. The assembled concrete underground main structure includes a main framework, structural walls, and structural slabs. The main framework includes a row of columns 2, a middle longitudinal beam 11, and a top longitudinal beam arranged in the middle of the foundation pit longitudinally. The columns 2 are concrete-filled steel tubes, and the middle longitudinal beam 11 and the top longitudinal beam are steel structures. The structural walls and structural slabs are all precast reinforced concrete components, and the columns 2 are constructed synchronously with the diaphragm wall 1.

[0055] Both ends of the middle longitudinal beam 11 are fixedly connected between the middle parts of the columns 2, and both ends of the top longitudinal beam are fixedly connected between the tops of the columns 2. The structural wall encloses the main frame along the inner wall of the diaphragm wall 1, including the lower wall 7 and the upper wall 6. The bottom of the lower wall 6 is connected to the floor slab 12, and the upper wall 6 and the lower wall 7 are fixedly connected in a vertically opposite manner. A precast corbel 61 is provided on the inner wall at the bottom of the upper wall 6. The structural slab includes a middle slab and a top slab. The transverse two ends of the middle slab are respectively fixedly connected to the top surfaces of the precast corbels 61 on the corresponding walls on the transverse two sides, the longitudinal middle part of the middle slab is fixedly connected to the top surface of the middle longitudinal beam 11, the ends of the top slab are respectively fixedly connected to the top surfaces of the corresponding upper walls 6 and the top surface of the capping beam 15, and the longitudinal middle part of the top slab is fixedly connected to the top surface of the top longitudinal beam.

[0056] The precast concrete underground main structure is divided into a reverse construction part and a forward construction part. The forward construction part and the reverse construction part are longitudinally arranged alternately in the foundation pit. The forward construction part is formed after the reverse construction part. The constructed structure of the reverse construction part also serves as the internal support in the foundation pit. The space between the constructed structures of the reverse construction part and the space to be constructed of the forward construction part also serves as the dynamic earth excavation and feeding port 20. In this embodiment, three reverse construction parts and two forward construction parts are provided.

[0057] Both the columns 2 and the middle longitudinal beam 11 are of the reverse construction part. The top longitudinal beam includes a reverse top beam 4 and a forward top beam 5. The structural wall includes a reverse wall and a forward wall. The middle slab includes a reverse middle slab 8 and a forward middle slab 9. The top slab includes a reverse top slab 3 and a forward top slab 10. The reverse top beam 4, the reverse wall, the reverse middle slab 8 and the reverse top slab 3 are all horizontally corresponding in the foundation pit. The forward top beam 5, the forward wall, the forward middle slab 9 and the forward top slab 10 are all horizontally corresponding in the foundation pit.

[0058] The construction lengths of the components in the reverse construction part are the same, and each construction length includes more than one of each component. In this embodiment, one of each component is taken as an example. The construction lengths of the components in the forward construction part are the same, and each construction length includes more than one of each component. In this embodiment, one of each component is taken as an example.

[0059] In this embodiment, as shown in Figure 10 and Figure 11 A flange plate 21 is fixedly connected to the outside of the connection position between the column 2 and the middle longitudinal beam 11. The bottom surface of the end of each middle longitudinal beam 11 is placed on the corresponding flange plate 21. A middle beam groove 111 adapted to the size of the column 2 is provided at the connection position between the end surface of each middle longitudinal beam 11 and the corresponding column 2. The remaining parts of the end surfaces of adjacent middle longitudinal beams 11 are fitted and butted. Each middle beam groove 111 is stuck on the side wall of the corresponding column 2. A flange plate connection hole 211 is opened on the flange plate 21, and a middle beam end connection vertical through hole 112 corresponding to the flange plate connection hole 211 is opened around the edge of the middle beam groove 111. The flange plate connection hole 211 and the middle beam end connection vertical through hole 112 are anchored by middle beam end connection bolts.

[0060] See Figure 8 As shown, there are two precast corbels 61 on the wall at the bottom of each upper wall. The precast corbels 61 on the wall are steel angle members. The vertical plate 611 of the steel angle member is anchored to the upper wall 6 through corbel connection bolts. There are corbel bolt holes 613 on the horizontal plate 612 of the steel angle member. There is a stiffening plate 614 between the vertical plate 611 and the horizontal plate 612. There are two columns of vertical through holes 113 for connecting the middle beam body on the middle longitudinal beam 11. At the position corresponding to the corbel bolt holes 613 at the transverse end of the middle plate, there are middle plate connection side through holes 13. At the longitudinal middle of the middle plate, there are middle plate connection middle through holes 14 corresponding to the vertical through holes 113 for connecting the middle beam body. The middle plate connection side through holes 13 and the corbel bolt holes 613, and the middle plate connection middle through holes 14 and the vertical through holes 113 for connecting the middle beam body are all anchored through middle plate connection bolts.

[0061] In this embodiment, there are six columns in three groups, and the middle longitudinal beam 11 is provided with five sections.

[0062] See Figure 14 、 Figure 15 、 Figure 16 、 Figure 17 、 Figure 23 and Figure 24 As shown, at the connection position between the middle plate and the column 2, there is a middle plate groove 23 adapted to the size of the column 2, and the remaining parts of the end faces of adjacent middle plates are fitted and butted. The reverse construction middle plate 8 includes a middle side plate 81 close to the transverse structural wall. The middle plate groove 23 of the middle side plate 81 forms a complete circular groove and a semi-circular groove. The remaining reverse construction middle plates 8 are middle plates 82, and the middle plate grooves 23 of the middle plates 82 form two semi-circular grooves. The reverse construction middle plate 8 is transversely divided into two half plates. Each half plate includes a column of middle plate connection middle through holes 14 and middle plate connection side through holes 13 on one side. The two half plates are assembled on the middle longitudinal beam 11. The half plate of the middle side plate 81 further includes a semi-circular groove and a quarter-circular groove. The half plate of the middle plate 82 further includes two quarter-circular grooves. The forward construction middle plate 9 is a whole plate, and the middle plate groove 23 of the forward construction middle plate 9 includes two semi-circular grooves. In this embodiment, there are two groups of middle side plates 81, one group of middle plates 82, and two forward construction middle plates 9 are provided.

[0063] See Figure 1 and Figure 23 As shown, in this embodiment, there are three sections of reverse construction top beams 4 and two sections of forward construction top beams 5. The column 2 is connected to the reverse construction top beam 4. At the connection position between the bottom of the reverse construction top beam 4 and the column 2, there is a column blind socket 41. The top of the column 2 is inserted into the column blind socket 41. At the position corresponding to the column 2 at the end of the reverse construction top beam 4, there are also beam-column connection bolt holes 42. The bottom of the beam-column connection bolt holes 42 communicates with the top of the column blind socket 41. There are column bolt blind holes 22 corresponding to the beam-column connection bolt holes 42 on the top surface of the column 2. The column bolt blind holes 22 and the beam-column connection bolt holes 42 are anchored through column bolts.

[0064] See Figure 2 、 Figure 3 and Figure 4 As shown, the cross-sections of the inverted beam 4 and the direct beam 5 are the same. The inverted beam 4 includes an integrally formed inverted beam main body 43 and an inverted beam top plate 44. The inverted beam top plate 44 is arranged on the top of the inverted beam main body 43. The width of the inverted beam top plate 44 is not greater than the top surface width of the inverted beam main body 43. The length of the inverted beam top plate 44 is less than the top surface length of the inverted beam main body 43 at the connection end of the inverted beam 4. Blind bolt holes 45 are provided in the part where the inverted beam main body 43 extends beyond the inverted beam top plate 44.

[0065] See Figure 25 and Figure 26 As shown, the direct beam 5 includes an integrally formed direct beam main body 51 and a direct beam top plate 52. The direct beam top plate 52 is arranged on the top of the direct beam main body 51. The width of the direct beam top plate 52 is not greater than the top surface width of the direct beam main body 51. The length of the direct beam top plate 52 is greater than the top surface length of the direct beam main body 51 at the connection end of the direct beam 5. Through bolt holes 53 corresponding to the blind bolt holes 45 are provided in the part where the direct beam top plate 52 extends beyond the direct beam main body 51.

[0066] See Figure 21 As shown, the connection ends of the inverted beam main body 43 and the direct beam main body 51 are in contact. The part where the direct beam top plate 52 extends is placed on the top surface where the inverted beam main body 43 extends. The end faces of the connection ends of the direct beam top plate 52 and the inverted beam top plate 44 are in contact. The blind bolt holes 45 and the through bolt holes 53 are anchored by beam connection bolts.

[0067] The cross-sections of the inverted beam main body 43 and the direct beam main body 51 are both T-shaped beams, including a beam flat plate 24 and a beam web 25. The column blind slots 41 are arranged in the beam web 25. The blind bolt holes 45 are arranged in the beam flat plate 24. Blind bolt holes 16 for beam and plate connection are arranged in rows on the top surfaces of the inverted beam top plate 44 and the direct beam top plate 52. The hole depth of the blind bolt holes 16 for beam and plate connection is greater than the thickness of the inverted beam top plate 44 or the direct beam top plate 52 and extends into the beam flat plate 24.

[0068] In this embodiment, see Figure 7 、 Figure 10 、 Figure 14 、 Figure 17 and Figure 20 As shown, there are three groups of inverted walls longitudinally opposite to each other, a total of six pieces in three longitudinal groups, which are the walls on both longitudinal sides of the structural wall. Each piece is further divided into an upper wall 6 and a lower wall 7. There are two groups of inverted walls transversely opposite to each other, a total of four pieces in two transverse groups, which are the walls on both transverse sides of the structural wall. See Figure 21 andFigure 28 As shown, there are two sets of longitudinal walls on the opposite sides of the structure wall, with a total of four walls in three longitudinal groups. Each wall is further divided into an upper wall 6 and a lower wall 7.

[0069] See Figure 8 、 Figure 18 and Figure 22 As shown in, a row of wall bolt blind holes 26 are provided at the vertical connection ends of the upper wall 6 and the lower wall 7. A rectangular operation opening 27 communicating with the inside wall of the structure wall is provided on the inner side wall of the structure wall for the wall bolt blind holes 26. The adjacent wall bolt blind holes 26 of the upper wall 6 and the lower wall 7 are anchored by wall docking bolts. The wall bolt blind holes 26 of the lower wall 7 are anchored to the bottom plate 12, and the wall bolt blind holes 26 of the upper wall 6 are anchored to the top plate through external wall bolts.

[0070] A half-thickness lap plate 40 is provided between the edges of horizontally adjacent structure walls. The thickness of the half-thickness lap plate 40 is equal to half of the thickness of the structure wall. The adjacent half-thickness lap plates 40 overlap and bite each other. Wall lap horizontal through holes 46 are provided on the half-thickness lap plate 40. The adjacent wall lap horizontal through holes 46 are aligned and anchored by wall lap bolts.

[0071] See Figure 1 、 Figure 5 and Figure 23 As shown in, blind connection holes 151 are provided on the top surface of the capping beam 15. A top plate connection middle through hole 17 is provided on the top plate corresponding to the beam plate connection bolt blind hole 16 of the top beam. A top plate connection wall through hole 47 is provided on the top plate corresponding to the wall bolt blind hole 26 of the upper wall 6. A top plate connection capping beam through hole 48 is provided on the top plate corresponding to the blind connection hole 151 of the capping beam. The top plate connection middle through hole 17 and the beam plate connection bolt blind hole 16, as well as the top plate connection wall through hole 47 and the blind connection hole 151 of the capping beam, are all anchored by top plate connection bolts. The top plate connection wall through hole 47 and the wall bolt blind hole 26 are anchored by external wall bolts.

[0072] See Figure 5 and Figure 23 As shown in, in other embodiments, longitudinal top beam connection grooves 29 are provided at the bottom of the top plate corresponding to the position of the top longitudinal beam. The depth of the top beam connection groove 29 is adapted to the thickness of the reverse construction top beam top plate 44 and the forward construction top beam top plate 52. The bottom of the top beam connection groove 29 is stuck on the top surfaces of the reverse construction top beam top plate 44 and the forward construction top beam top plate 52. The bottom of the top beam is placed on the top surfaces of the reverse construction top beam main body 43 and the forward construction top beam main body 51.

[0073] See Figure 23 As shown in, the water stop structure includes a grouting water stop layer 18 filled between the structure wall and the foundation pit maintenance structure, a waterproof layer 19 applied on the top surface of the top plate, and also includes water stop strips 28 provided at the edges of the top plate, the lower wall 6, the upper wall 7, the reverse construction middle plate 8, and the forward construction middle plate 9. SeeFigure 29 As shown, taking the inverted middle slab 8 as an example.

[0074] The construction method for the combined inverted and upright construction of this prefabricated steel-concrete underground structure with inverted and upright combination is as follows: Step 1: Conduct surveying and setting out on the construction site to determine the specific position of the foundation pit retaining structure; excavate the guide wall trench and construct the guide wall; then, according to the construction drawing design, under the condition of slurry wall protection, use grooving equipment to excavate the trench of the foundation pit retaining structure and clean the bottom; then construct the diaphragm wall 1 in the trench.

[0075] Step 2: Start constructing the inverted part and construct the columns 2: Conduct surveying and setting out on the construction site synchronously with Step 1 to determine the specific position of the columns; according to the construction drawing design, under the condition of slurry wall protection, use hole-forming equipment to excavate the column holes and clean the bottom; then construct the columns 2 in the holes.

[0076] Step 3: Excavate the soil downward in the area enclosed by the diaphragm wall 1 to the bottom elevation of the top slab and the top longitudinal beam.

[0077] Step 4: Construct the capping beam 15 and the inverted top beam 4, and fixedly connect the inverted top beam 4 to the columns 2: Construct the capping beam 15 at the top of the diaphragm wall 1; at the same time, hoist the inverted top beam 4 piece by piece, insert the top of the column 2 into the column blind slot 41, align the column bolt blind hole 22 with the beam-column connection bolt hole 42 and anchor with column bolts, as shown in Figure 1 - 4 shown.

[0078] Step 5: Construct the inverted top slab 3 and fixedly connect the inverted top slab 3 to the capping beam 15 and the inverted top beam 4: Hoist the inverted top slab 3 piece by piece, align the through hole 17 in the top slab connection with the beam-slab connection bolt blind hole 16 of the inverted top beam 4, and align the through hole 47 in the top slab connection wall with the capping beam connection blind hole 151, and all are anchored with top slab connection bolts, as shown in Figure 5 - 6 shown.

[0079] Step 6: Construct the upper steel wall installation brackets 30 and hydraulic jacks 31: Continue to excavate the soil downward to the bottom elevation of the upper steel wall installation brackets 30, and then anchor and connect the steel wall installation brackets 30 to the reserved bolt holes on the inner wall of the diaphragm wall. The steel wall installation brackets 30 are provided with hydraulic jacks 31. Each group of steel wall installation brackets 30 and hydraulic jacks 31 are arranged at the bottom of the structure wall to be installed and are symmetrically provided with two groups.

[0080] Step 7: Construct the upper wall 6 of the inverted wall, and fixedly connect the upper wall 6 of the inverted wall to the inverted top slab 3 and the upper wall 6 adjacent to the inverted wall: Lift the upper wall 6 piece by piece, place it on the steel wall installation bracket 30, then start the hydraulic jack 31 to closely attach the top surface of the upper wall 6 to the bottom surface of the roof slab; then align the through holes 47 in the roof slab connecting wall with the blind holes 26 in the wall bolts and anchor them through the external wall bolts. Anchor the upper walls 6 between adjacent reverse construction walls through the aligned horizontal through holes 46 in the wall lap joint and the wall lap joint bolts. Then remove the upper steel wall installation bracket 30 and the hydraulic jack 31, and seal the reserved bolt holes. See Figure 7 - 10 as shown.

[0081] Step eight, construct the middle longitudinal beam during construction, and fixedly connect the middle longitudinal beam 11 to the middle column 2: Lift the middle longitudinal beam 11 one by one and place the middle longitudinal beam 11 on the flange 21 preset on the column 2. See Figure 10 - 11 as shown. Align the connection holes 211 in the flange with the vertical through holes 112 at the end of the middle beam and anchor them through the bolts at the end of the middle beam. See Figure 12 - 13 as shown.

[0082] Step nine, construct the reverse construction middle slab 8, and fixedly connect the reverse construction middle slab 8 to the upper wall 6 of the reverse construction wall and the middle longitudinal beam 11: Lift the reverse construction middle slab 8 piece by piece. Place the two ends of the reverse construction middle slab 8 on the precast brackets 61 on the wall of the upper wall 6 in step seven and the middle longitudinal beam 11 respectively. Align the through holes 13 on the connecting edge of the middle slab with the bolt holes 613 in the bracket, and align the middle through hole 14 in the middle slab with the vertical through hole 113 connecting the middle beam body. Anchor them all through the bolts connecting the middle slab. See Figure 14 - 16 as shown.

[0083] Step ten, construct the lower steel wall installation bracket 30 and the hydraulic jack 31: Continue to excavate the soil downward to the bottom elevation position of the lower steel wall installation bracket 30. Install the steel wall installation bracket 30 and the hydraulic jack 31 in the same way as in step six. See Figure 17 as shown.

[0084] Step eleven, construct the lower wall 7 of the reverse construction wall, and fixedly connect the lower wall 7 of the reverse construction wall to the upper wall 6 of the reverse construction wall and the adjacent lower walls 7 of the reverse construction wall: Lift the lower wall 7 piece by piece, place it on the steel wall installation bracket 30, then start the hydraulic jack 31 to closely attach the top surface of the lower wall 7 to the bottom surface of the upper wall 6; align the blind holes 26 in the wall bolts between the upper wall 6 and the adjacent lower wall 7 and anchor them through the butt bolts of the wall; anchor the adjacent lower walls 7 of the reverse construction walls through the aligned horizontal through holes 46 in the wall lap joint and the wall lap joint bolts. Then remove the lower steel wall installation bracket 30 and the hydraulic jack 31, and seal the reserved bolt holes. See Figure 17 - 20 as shown.

[0085] Step Twelve, construct the floor slab 12, and fixedly connect the lower wall 7 of the reverse construction wall with the floor slab 12: Pour the floor slab 12, and reserve floor slab bolt holes during pouring for connection with the wall bolt blind holes 26 at the bottom of the lower wall 7; wait for the floor slab 12 to reach the designed strength.

[0086] Step Thirteen, start constructing the forward construction part, construct the lower wall 7 of the forward construction wall, and fixedly connect the lower wall 7 of the forward construction wall with the floor slab 12 and the adjacent lower wall 7 of the forward construction wall: Lift and install the lower wall 7 piece by piece. The wall bolt blind holes 26 at the bottom of the lower wall 7 are anchored with the floor slab bolt holes through floor slab connection bolts, and the adjacent lower walls 7 are anchored through the aligned horizontal through holes 46 for wall lapping and wall lapping bolts.

[0087] Step Fourteen, construct the upper wall 6 of the forward construction wall, and fixedly connect the upper wall 6 of the forward construction wall with the lower wall 7 of the forward construction wall and the adjacent upper wall 6 of the forward construction wall: Lift and install the upper wall 6 piece by piece, and closely attach the bottom surface of the upper wall 6 to the top surface of the lower wall 7; the adjacent upper walls 6 are anchored through the aligned horizontal through holes 46 for wall lapping and wall lapping bolts, as shown in Figure 21 - 22 shown.

[0088] Step Fifteen, construct the forward construction middle slab 9, and fixedly connect the forward construction middle slab 9 with the upper wall 6 of the forward construction wall and the middle longitudinal beam 11: Lift and install the forward construction middle slab 9 piece by piece, place the two ends of the forward construction middle slab 9 on the precast corbels 61 on the wall of the upper wall 6 in Step Fourteen and the middle longitudinal beam 11 respectively. Align the through holes 13 at the connecting edges of the middle slab with the corbel bolt holes 613, and align the through holes 14 in the middle of the middle slab with the vertical through holes 113 for connecting the middle beam body. All are anchored through middle slab connection bolts, that is, the forward construction middle slab 9 is fixedly connected with the upper wall 6 of the forward construction wall and the middle longitudinal beam 11; the forward construction middle slab 9 is also fixedly connected with the adjacent reverse construction middle slab 8.

[0089] Step Sixteen, construct the forward construction top beam 5, and fixedly connect the forward construction top beam 5 with the adjacent reverse construction top beam 4: Lift and install the forward construction top beam 5 one by one, make the end faces of the connecting ends of the top plate 52 of the forward construction top beam and the top plate 44 of the reverse construction top beam fit, and align the bolt blind holes 45 under the top beam with the bolt through holes 53 on the top beam and anchor them through the top beam connection bolts.

[0090] Step Seventeen, construct the forward construction top slab 10, and fixedly connect the forward construction top slab 10 with the crown beam 15 and the upper wall 6 of the forward construction wall: Lift and install the top slab 10 piece by piece. Align the through holes 17 in the connection of the top slab with the blind holes 16 of the beam-slab connection bolts of the top beam 5 constructed in sequence. Align the through holes 47 in the connection of the top slab with the wall with the blind holes 151 for the connection with the capping beam, and anchor them all with the connection bolts of the top slab. That is, the top slab 10 constructed in sequence is fixedly connected to the top beam 5 constructed in sequence and the upper wall 6. Align the through holes 47 in the connection of the top slab with the wall with the blind holes 26 of the wall bolts and anchor them with the external connection bolts of the wall. That is, the top slab 10 constructed in sequence is fixedly connected to the capping beam 15. The top slab 10 constructed in sequence is also fixedly connected to the adjacent top slab 3 constructed in reverse order. See Figure 23 - 28 as shown.

[0091] Step 18: After the construction of the prefabricated concrete underground main structure and the floor slab 12 is completed, perform filling grouting between the outside of the wall structure and the inside of the diaphragm wall 1 to form a grouting water-stop layer 18. See Figure 23 as shown.

[0092] Step 19: Construct a waterproof layer 19 above the top slab. See Figure 23 as shown.

[0093] Step 20: Backfill the soil above the top slab and restore the original ground surface.

Claims

1. An assembled reverse and forward combined steel-concrete underground structure, characterized in that: include: The foundation pit retaining structure includes an underground continuous wall (1) and a cap beam (15) on its top, both of which are steel, prefabricated or cast-in-place structures; a cast-in-place concrete base plate (12); The assembled concrete underground main structure includes: The main frame includes a steel tube concrete column (2) in the middle of the longitudinal direction, a middle longitudinal beam (11) of the steel structure connecting the middle of the column, and a top longitudinal beam of the steel structure connecting the top of the column; The structural wall body enclosed outside the main frame along the inner wall of the underground continuous wall (1) comprises a lower wall (7) and an upper wall (6) with a prefabricated corbel (61) on the bottom inner wall, and the bottom of the lower wall (7) is connected to the bottom plate (12); the upper wall (6) and the lower wall (7) are fixedly connected and arranged vertically opposite to each other. The structural plate body comprises a middle plate fixed simultaneously to the top surface of the prefabricated corbel (61) on the wall and the middle longitudinal beam (11), and a top plate fixed simultaneously to the top surface of the upper wall (6), the crown beam (15) and the top longitudinal beam; The water-stop structure includes a grouting water-stop layer (18) between the structural wall and the underground continuous wall, a waterproof layer (19) on the upper side of the top plate, and water-stop strips (28) at the joints of each component; The structure is divided into a top-down construction part and a sequential construction part. The two parts are arranged alternately and the sequential construction part is formed after the top-down construction part. The constructed structures of the top-down construction part also serve as support in the foundation pit. The space between the constructed structures of the top-down construction part and the space to be constructed of the sequential construction part also serve as a dynamic excavation feed port (20). According to the construction timing, the top longitudinal beam includes a reverse top beam (4) and a forward top beam (5), the structural wall includes a reverse wall and a forward wall, the middle plate includes a reverse middle plate (8) and a forward middle plate (9), and the top plate includes a reverse top plate (3) and a forward top plate (10). The reverse construction part comprises a column (2) and a middle longitudinal beam (11), and also comprises a reverse construction top beam (4), a reverse construction wall, a reverse construction middle plate (8) and a reverse construction top plate (3) which are arranged in a transverse direction in a foundation pit in a corresponding manner, and the forward construction part comprises a forward construction top beam (5), a forward construction wall, a forward construction middle plate (9) and a forward construction top plate (10) which are arranged in a transverse direction in a foundation pit in a corresponding manner.

2. The assembled reverse and forward combined steel-concrete underground structure according to claim 1 is characterized by: A flange (21) supporting the middle longitudinal beam (11) is fixedly sleeved on the column (2); an end surface of each middle longitudinal beam (11) is provided with a middle beam groove (111) clamped with the column (2); a flange connection hole (211) is provided on the flange (21); a middle beam end connection vertical through hole (112) corresponding to the flange connection hole (211) is provided around the edge of the middle beam groove (111); the flange connection hole (211) and the middle beam end connection vertical through hole (112) are anchored by bolts.

3. The assembled reverse and forward combined steel-concrete underground structure according to claim 1 is characterized by: A middle plate groove (23) for clamping the column is provided at the connection position between the middle plate and the column (2), and the remaining parts of the adjacent middle plates are fitted and butted. The prefabricated corbel (61) on the wall is a steel angle piece with a vertical plate (611), a horizontal plate (612) and a stiffening plate (614); the vertical plate (611) is anchored to the upper wall (6) by bolts; a middle plate connecting side through hole (13) is opened at a position corresponding to the corbel bolt hole (613) of the horizontal plate (612) at the transverse end of the middle plate; a middle plate connecting middle through hole (14) is opened at a position corresponding to the middle beam body connecting vertical through hole (113) of the middle longitudinal beam (11); the middle plate connecting side through hole (13) and the corbel bolt hole (613), and the middle plate connecting middle through hole (14) and the middle beam body connecting vertical through hole (113) are all anchored by bolts.

4. The assembled reverse and forward combined steel-concrete underground structure according to claim 1 is characterized by: The reverse top beam (4) is fixedly connected to the column, the bottom of the reverse top beam (4) is provided with a column blind slot (41) for the top of the column (2) to be inserted, the end of the reverse top beam (4) is provided with a beam-column connecting bolt hole (42) connected to the top of the column blind slot (41), the top surface of the column (2) is provided with a column bolt blind hole (22) corresponding to the beam-column connecting bolt hole (42), and the column bolt blind hole (22) is anchored to the beam-column connecting bolt hole (42) by bolts.

5. The assembled reverse and forward combined steel-concrete underground structure according to claim 4 is characterized by: The forward-made top beam (5) is fixedly connected between adjacent reverse-made top beams (4), and the reverse-made top beam (4) has the same cross section as the forward-made top beam (5); the reverse-made top beam (4) comprises a reverse-made top beam body (43) at the bottom and a reverse-made top beam top plate (44) at the top, and a top beam lower bolt blind hole (45) is formed in the reverse-made top beam body (43) at the longitudinal connection end extending out of the reverse-made top beam top plate (44); the forward-made top beam (5) comprises a forward-made top beam body (51) at the bottom and a forward-made top beam top plate (44) at the top. A top beam top plate (52) is provided, and a top beam upper bolt through hole (53) corresponding to the top beam lower bolt blind hole (45) is opened at the portion of the longitudinal connection end of the top beam top plate (52) extending out of the longitudinal top beam main body (51); the reverse top beam (4) is fitted with the longitudinal connection end of the forward top beam (5), and the extended portion of the top beam top plate (52) is placed on the extended top surface of the reverse top beam main body (43), and the top beam lower bolt blind hole (45) and the top beam upper bolt through hole (53) are anchored by bolts.

6. The assembled reverse and forward combined steel-concrete underground structure according to claim 5 is characterized by: The cross-sections of the reverse-built top beam body (43) and the forward-built top beam body (51) are both T-shaped beams, including a beam plate (24) and a beam web (25). The column blind slot (41) is arranged in the beam web (25). The top beam lower bolt blind hole (45) is arranged in the beam plate (24). The reverse-built top beam top plate (44) and the forward-built top beam top plate (52) are both provided with beam-plate connecting bolt blind holes (16) in a row. The hole depth of the beam-plate connecting bolt blind holes (16) is greater than the thickness of the reverse-built top beam top plate (44) or the forward-built top beam top plate (52) and extends into the beam plate (24).

7. The assembled reverse and forward combined steel-concrete underground structure according to claim 6 is characterized by: The vertical connection ends of the upper wall (6) and the lower wall (7) are each provided with a row of wall bolt blind holes (26), and the inner wall thereof is provided with a rectangular operation opening (27) connected to the wall bolt blind holes (26). The upper and lower adjacent wall bolt blind holes (26) are anchored by bolts, and the wall bolt blind holes (26) of the lower wall (7) and the bottom plate (12) and the wall bolt blind holes (26) of the upper wall (6) and the top plate are anchored by bolts; the edges of the horizontally adjacent structural walls are overlapped and interlocked with each other by using a half-thick overlap plate (40), and the wall overlap horizontal through holes (46) provided on the half-thick overlap plate (40) are aligned and anchored by bolts.

8. The assembled reverse and forward combined steel-concrete underground structure according to claim 7 is characterized by: The top surface of the crown beam (15) is provided with a crown beam connection blind hole (151); the top plate is provided with a top plate connection middle through hole (17), a top plate connection wall through hole (47) and a top plate connection crown beam through hole (48), which respectively correspond to the beam-plate connection bolt blind hole (16) of the top beam, the wall bolt blind hole (26) of the upper wall (6) and the crown beam connection blind hole (151); the top plate connection middle through hole (17) and the beam-plate connection bolt blind hole (16), the top plate connection wall through hole (47) and the crown beam connection blind hole (151), and the top plate connection wall through hole (47) and the wall bolt blind hole (26) are all anchored by bolts; the bottom of the top plate is provided with a longitudinal top beam connection groove (29), the groove depth and groove width of which are both adapted to the thickness and width of the reverse top beam top plate (44) and the forward top beam top plate (52), and the top beam connection groove (29) is clamped to the top surface of the top beam.

9. A method for combining reverse and forward operations of an assembled reverse and forward combined steel-concrete underground structure according to any one of claims 1 to 8, characterized in that: The construction steps are as follows: Step 1: after surveying and laying out, excavate a guide wall trench and construct a guide wall; use trenching equipment to excavate a trench for the foundation pit retaining structure under the mud wall and clean the bottom; construct an underground continuous wall in the trench (1); Start construction of reverse work department: Step 2: Constructing the columns (2) simultaneously with the underground continuous wall (1); after measuring and setting out, using a hole-making device to dig holes for the columns under the mud wall and clean the bottom; constructing the columns (2) in the holes; Step 3: excavating earth downwards in the area enclosed by the underground continuous wall (1) to the bottom elevation of the top plate and the top longitudinal beam; Step 4: construct the crown beam (15) and the reverse top beam (4), and fix the reverse top beam (4) to the column (2); Step 5: constructing a reverse-built top plate (3), and fixing and connecting the reverse-built top plate (3) with the crown beam (15) and the reverse-built top beam (4); Step 6: construct the upper steel wall installation bracket (30) and the hydraulic jack (31): continue to excavate the earth downward to the bottom elevation of the upper steel wall installation bracket (30), anchor the steel wall installation bracket (30) to the underground continuous wall, and provide a hydraulic jack (31) on the steel wall installation bracket (30). Each set of steel wall installation bracket (30) and hydraulic jack (31) is arranged at the bottom of the structural wall to be installed; Step 7, constructing the upper wall (6) of the reverse-built wall, and fixing the upper wall (6) of the reverse-built wall with the reverse-built top plate (3) and the upper wall (6) adjacent to the reverse-built wall; wherein the upper wall (6) is installed with the assistance of a steel wall mounting bracket (30) and a hydraulic jack (31); Step 8: construct the middle longitudinal beam and fix the middle longitudinal beam (11) to the middle column (2); Step nine, constructing a reverse-constructed middle plate (8), and fixing the reverse-constructed middle plate (8) to the upper wall (6) and the middle longitudinal beam (11) of the reverse-constructed wall; Step 10, construct the lower steel wall installation bracket (30) and the hydraulic jack (31): continue to excavate the earth downward to the bottom elevation of the lower steel wall installation bracket (30), and install the steel wall installation bracket (30) and the hydraulic jack (31) in the same way as step 6; Step eleven, constructing a lower wall (7) of the reverse-built wall, and fixing the lower wall (7) of the reverse-built wall to the upper wall (6) of the reverse-built wall and the lower wall (7) adjacent to the reverse-built wall; Step 12: constructing the bottom plate (12), fixing and connecting the lower wall (7) of the reverse wall to the bottom plate (12), and waiting for the bottom plate (12) to reach the designed strength; Start construction of the sequential work section. At this time: Step 13, constructing the lower wall (7) of the sequential wall, and fixing the lower wall (7) of the sequential wall with the bottom plate (12) and the lower wall (7) adjacent to the sequential wall; Step 14: constructing the upper wall (6) of the sequential wall, and fixing the upper wall (6) of the sequential wall with the lower wall (7) of the sequential wall and the adjacent upper wall (6) of the sequential wall; Step 15, constructing the forward middle plate (9), and fixing the forward middle plate (9) to the upper wall (6) and the middle longitudinal beam (11) of the forward wall; the forward middle plate (9) is also fixedly connected to the adjacent reverse middle plate (8); Step 16, constructing the forward-constructed top beam (5), and fixing the forward-constructed top beam (5) to the adjacent reverse-constructed top beam (4); Step 17: constructing the top plate (10) of the construction, and fixing the top plate (10) with the top beam (5), the upper wall (6) and the crown beam (15); the top plate (10) of the construction is also fixedly connected with the adjacent top plate (3) of the construction; Step 18, after the construction of the assembled concrete underground main structure and the bottom plate (12) is completed, grouting is performed between the outer side of the wall structure and the inner side of the underground continuous wall (1) to form a grouting water stop layer (18); Step 19, applying a waterproof layer (19) above the top plate; Step 20: backfill the soil above the top plate to restore the original ground state.

10. The reverse and forward combined construction method of the assembled reverse and forward combined steel-concrete underground structure according to claim 9 is characterized in that: In step 4, the reverse top beam (4) is specifically constructed as follows: the reverse top beam (4) is hoisted piece by piece, the top of the column (2) is inserted into the column blind slot (41), the column bolt blind hole (22) is aligned with the beam-column connecting bolt hole (42), and then anchored by bolts; In step 5, the reverse top plate (3) is specifically constructed as follows: the reverse top plate (3) is hoisted piece by piece, the top plate connection middle through hole (17) is aligned with the beam-plate connection bolt blind hole (16) of the reverse top beam (4), and the top plate connection wall through hole (47) is aligned with the crown beam connection blind hole (151), and all are anchored by bolts; In step 7, the upper wall (6) of the reverse wall is specifically constructed as follows: the upper wall (6) is hoisted piece by piece and placed on the steel wall mounting bracket (30), and the hydraulic jack (31) is started to make the top surface of the upper wall (6) close to the bottom surface of the top plate; the top plate connecting wall through hole (47) is aligned with the wall bolt blind hole (26) and anchored by bolts, the adjacent upper walls (6) are overlapped and anchored by bolts, and then the steel wall mounting bracket (30) and the hydraulic jack (31) are removed; In step eight, the specific construction of the middle longitudinal beam is as follows: the middle longitudinal beams (11) are hoisted one by one, the middle longitudinal beams (11) are placed on the flange plate (21), the flange plate connection hole (211) is aligned with the middle beam end connection vertical through hole (112) and anchored by bolts; In step nine, the reverse middle plate is specifically constructed as follows: hoist the reverse middle plate (8) piece by piece and place the two ends of the reverse middle plate on the wall prefabricated corbels (61) and the middle longitudinal beam (11) of the upper wall (6) in step seven, align the middle plate connecting side through holes (13) with the corbel bolt holes (613), align the middle plate connecting middle through holes (14) with the middle beam body connecting vertical through holes (113), and all are anchored by bolts; In step 11, the specific construction of the lower wall (7) of the reverse wall is as follows: the lower wall (7) is hoisted piece by piece and placed on the steel wall mounting bracket (30), and the hydraulic jack (31) is started to make the top surface of the lower wall (7) close to the bottom surface of the upper wall (6); the upper and lower adjacent wall bolt blind holes (26) are aligned and anchored by bolts; the adjacent lower walls (7) are overlapped and anchored by bolts, and then the steel wall mounting bracket (30) and the hydraulic jack (31) are removed; In step 12, when pouring the bottom plate (12), a bottom plate bolt hole connected to the wall bolt blind hole (26) at the bottom of the lower wall (7) of the subsequent wall is reserved; In step 13, the specific construction of the lower wall (7) of the wall body is as follows: the lower wall (7) is hoisted piece by piece, the wall bolt blind hole (26) at the bottom of the lower wall (7) is anchored with the bottom plate bolt hole in step 12 by bolts, and the adjacent lower walls (7) are overlapped and anchored by bolts; In step 14, the specific construction of the upper wall (6) of the wall body is as follows: the upper wall (6) is hoisted piece by piece, and the bottom surface of the upper wall (6) is closely attached to the top surface of the lower wall (7); the adjacent upper walls (6) are overlapped and anchored by bolts; In step 15, the specific construction of the middle plate (9) is as follows: the middle plates (9) are hoisted piece by piece and the two ends are respectively placed on the wall prefabricated corbels (61) of the upper wall (6) in step 14 and fixedly connected on the middle longitudinal beam (11); wherein the middle plate connecting side through holes (13) are aligned with the corbel bolt holes (613), and the middle plate connecting middle through holes (14) are aligned with the middle beam body connecting vertical through holes (113), and all are anchored by bolts; In step 16, the specific construction of the forward-made top beam (5) is as follows: hoisting the forward-made top beams (5) one by one, and fitting the connecting end faces of the forward-made top beam (5) and the reverse-made top beam (4) together, aligning the bolt blind holes (45) under the top beam with the bolt through holes (53) on the top beam, and anchoring them with bolts; In step seventeen, the specific construction of the top plate (10) is as follows: the top plate (10) is constructed by hoisting the plates one by one, and the connecting middle through hole (17) is aligned with the beam-plate connecting bolt blind hole (16) of the top beam (5), the top plate connecting wall through hole (47) is aligned with the crown beam connecting blind hole (151), and both are anchored by bolts, and the top plate connecting wall through hole (47) is aligned with the wall bolt blind hole (26) and anchored by bolts.

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