Underground structure permanent and temporary combined support system and construction method

Abstract

The application relates to the technical field of subway supporting structures, and discloses an underground structure permanent-temporary combined supporting system and a construction method, which comprises a surrounding structure, a top plate, a middle plate, a bottom plate and side walls; the top plate comprises a crown beam, a first longitudinal beam and a first cross brace, and a plurality of first cross braces are arranged at intervals along the length direction of the first longitudinal beam; the middle plate comprises a waist beam, a second longitudinal beam and a second cross brace, and a plurality of second cross braces are arranged at intervals along the length direction of the second longitudinal beam; permanent structure plates are arranged between two adjacent first cross braces and between two second cross braces, and the permanent structure plates are prefabricated plates or cast-in-situ plates formed by adopting a modular formwork pouring method. The permanent structure plates are formed by using prefabricated plates or cast-in-situ plates formed by adopting a modular formwork pouring method, and do not have a superposition layer structure, so that it is not necessary to bind steel bars and pour concrete again during back construction; the permanent structure plates are formed by one-time pouring, and it is not necessary to arrange temporary steel bars or exposed reserved tension bars, so that the waste and rust of the steel bars are reduced.

Description

Technical Field

[0001] This invention relates to the field of subway support structure technology, and in particular to a permanent and temporary combined support system and construction method for underground structures. Background Technology

[0002] When existing underground structures are constructed using open-cut excavation, temporary concrete supports are typically used for foundation pit support during the excavation process. These temporary supports require on-site reinforcement cage binding and formwork installation after excavation, followed by concrete pouring, and excavation can only continue after the concrete has reached its set curing period. After excavation, the temporary concrete supports must be removed, resulting in significant pollution and energy consumption, which contradicts the trend towards green and environmentally friendly development.

[0003] Based on the concept of combining permanent and temporary structures, the foundation pit support system is designed reasonably according to the layout requirements of the permanent structure. The internal support system of the foundation pit project is integrated into the permanent structure, avoiding the need to dismantle the existing foundation pit support system in the later stage. This is the development direction of modern subway support systems.

[0004] For example, patent CN212506415U discloses a permanent-temporary combined open-cut and longitudinal construction structure for a subway station, including a retaining structure and a main structure. The main structure includes a precast top slab, a precast middle slab, and columns. The precast top slab is located above the precast middle slab, and the columns are vertically positioned in the middle of the precast top slab and the precast middle slab. The retaining structure includes a first support, a second support, and steel lattice columns. The first support and the precast top slab support are connected to form a permanent-temporary combined top slab structure, the second support and the precast middle slab support are connected to form a permanent-temporary combined middle slab structure, and the columns and steel lattice columns are connected to form a permanent-temporary combined column structure. In this permanent-temporary combined open-cut and longitudinal construction structure for a subway station, some floor slabs are constructed during the foundation pit stage as a foundation pit support system. Each floor slab is a composite component. During the backfilling stage, the reinforcement bars of each floor slab are tied again, and the composite layer is re-cast to form each floor slab.

[0005] Authorization announcement number CN212001126U discloses a combined permanent and temporary concrete support and structural top slab construction system, including an underground structure, retaining piles, wainscoting, and concrete supports. The retaining piles are located on the outer perimeter of the underground structure, with the pile tops above the top slab of the underground structure at a certain distance and the pile bottoms below the bottom slab of the underground structure at a certain distance. Wainscoting is provided on the inner side of the retaining piles, and the concrete supports are rigidly connected to the wainscoting on both sides, with the concrete supports located above the top of the underground structure. The top slab of this combined permanent and temporary construction system is formed by concrete supports and backfill soil. During the backfilling stage, the backfill soil is poured onto the concrete supports to form the top slab.

[0006] However, the floor of the permanent and temporary combined scheme described above all adopts a composite floor, that is, only the floor within a certain height range is poured during the foundation pit stage, such as a prefabricated top plate or a concrete support, and then a second pouring is performed during the back pouring stage, such as a top plate cast-in-place layer or concrete, so that the face wire of the support beam is only used as temporary reinforcement and is not stressed in the permanent stage, resulting in a certain waste, and the face wire in the cast-in-place layer during the back pouring stage needs to be bound twice, which is slow in construction efficiency; the reserved tensioning wire between the temporary support and the cast-in-place composite layer needs to be exposed all the time during the foundation pit stage, which is difficult to protect on site and is difficult to avoid rust and other situations. SUMMARY

[0007] The purpose of the present application is to provide an underground structure permanent and temporary combined support system to solve the problems of the existing technology that the permanent and temporary structure floor adopts a composite structure, the construction efficiency of the back pouring operation is slow, the temporary reinforcement is wasted, and the reserved tensioning wire rusts; the present application also provides an underground structure permanent and temporary combined support construction method.

[0008] In order to achieve the above purpose, the present application provides an underground structure permanent and temporary combined support system, which comprises a surrounding structure, the surrounding structure is sequentially arranged from top to bottom with a top plate, a middle plate and a bottom plate, and a side wall is arranged between the top plate and the middle plate and between the middle plate and the bottom plate;

[0009] The top plate comprises a crown beam arranged in a ring shape around the inner wall of the surrounding structure, a first row of longitudinal beams and a first row of cross braces are connected in the crown beam, the first row of longitudinal beams and the first row of cross braces are arranged perpendicular to each other, and a plurality of first row cross braces are arranged along the length direction of the first row of longitudinal beams;

[0010] The middle plate comprises a waist beam arranged in a ring shape around the inner wall of the surrounding structure, a second row of longitudinal beams and a second row of cross braces are connected in the waist beam, the second row of longitudinal beams and the second row of cross braces are arranged perpendicular to each other, and a plurality of second row cross braces are arranged along the length direction of the second row of longitudinal beams;

[0011] A permanent structure plate is arranged between adjacent two first row cross braces and between adjacent two second row cross braces, the permanent structure plate is a prefabricated plate or a cast-in-place plate formed by using a modular formwork pouring;

[0012] The crown beam and the waist beam are connected with the side wall between the waist beam and the bottom plate, coaxially arranged structure columns are further connected between the top plate and the middle plate and between the middle plate and the bottom plate, the structure columns are arranged at the connection positions of the first row of longitudinal beams and the first row of cross braces and the second row of longitudinal beams and the second row of cross braces, and a plurality of structure columns are arranged at intervals;

[0013] A first waterproof structure is arranged between the crown beam and the enclosure, a second waterproof structure is arranged on the construction joint of the side wall, and a third waterproof structure is arranged on the construction joint of the top plate, the middle plate and the bottom plate.

[0014] Preferably, a steel bar adapter is pre-buried on the inner side of the enclosure, and the steel bars in the crown beam and the steel bars in the waist beam are fixedly connected with the steel bar adapter.

[0015] Preferably, a vibration exhaust pipe is pre-set in the crown beam, the waist beam, the first longitudinal beam and the second longitudinal beam.

[0016] Preferably, the first waterproof structure comprises a cement-based permeable crystalline coating, the cement-based permeable crystalline coating is arranged between the end face of the crown beam and the inner wall of the enclosure, and polythiourethane sealant is arranged at the upper and lower ends of the cement-based permeable crystalline coating.

[0017] Preferably, the second waterproof structure comprises an expansion waterproof glue strip and an externally attached waterproof tape, the externally attached waterproof tape is attached to the outer side of the construction joint, a grouting pipe is pre-buried at the construction joint of the side wall, and the expansion waterproof glue strip is arranged on the inner and outer sides of the grouting pipe.

[0018] Preferably, the third waterproof structure comprises an expansion waterproof glue strip and a galvanized steel plate waterproof tape, the galvanized steel plate waterproof tape is arranged through the construction joint, the expansion waterproof glue strip is arranged on the inner and outer sides of the galvanized steel plate waterproof tape, and an externally attached waterproof tape is further arranged on the outer side of the construction joint.

[0019] Preferably, a waterproof roll is further arranged between the crown beam and the enclosure, between the waist beam and the enclosure, between the side wall and the enclosure, and between the bottom plate and the enclosure, and the waterproof roll is arranged in a lap joint closed loop.

[0020] The application further provides a permanent and temporary combined supporting construction method for an underground structure, which adopts the underground structure permanent and temporary combined supporting system in the above technical solution and comprises the following steps: step one, pre-buried arrangement of a steel bar adapter in an enclosure, excavation of a foundation pit, excavation of the foundation pit to a design elevation of a crown beam, erection of an adjustable flat formwork as a construction formwork, arrangement of a first waterproof structure between the crown beam and the enclosure, arrangement of a third waterproof structure at a construction joint of a top plate, pre-setting of a vibration exhaust pipe and a steel bar adapter below the crown beam, the first cross brace and the first longitudinal beam, and pouring and forming of the crown beam, the first cross brace and the first longitudinal beam;

[0021] Step two, continuous excavation to a design elevation of a waist beam, erection of an adjustable flat formwork as a construction formwork, pouring and forming of the waist beam, the second cross brace and the second longitudinal beam, pre-setting of a vibration exhaust pipe and a steel bar adapter below the waist beam and the second longitudinal beam, arrangement of a third waterproof structure at a construction joint of a middle plate, pouring of a side wall and a structural column.

[0022] Step three, excavate the foundation pit to the bottom plate height, enter the back construction stage, first apply the concrete cushion layer, then arrange the waterproof roll, arrange the second waterproof structure at the construction joint of the side wall, arrange the third waterproof structure at the construction joint of the bottom plate, and pour and form the bottom plate, side wall and structure column;

[0023] Step four, install the modular hanging formwork with the first support and the second support as the fulcrum, and use the modular hanging formwork to pour and form the cast-in-place plate as the permanent structure plate on site; or hang the prefabricated plate as the permanent structure plate.

[0024] Preferably, in steps one and two, when the adjustable formwork is in use, the foundation pit is excavated to below the top plate or the middle plate, and the base, the hydraulic jack, the main batten and the secondary batten are sequentially assembled from bottom to top, the hydraulic jack is connected between the main batten and the secondary batten, the side formwork and the movable rib plate are installed on the secondary batten, the side formwork is moved to the set position by using the movable rib plate, and after assembling each formwork, the formwork is leveled by the jack, and pouring is implemented.

[0025] Preferably, in step four, after the permanent structure plate of the top plate is assembled, the original slurry is used for leveling, non-solidified rubber asphalt waterproof paint is first applied, self-adhesive modified asphalt waterproof roll is then laid, and the joint between the self-adhesive modified asphalt waterproof roll and the enclosure structure is sealed and closed.

[0026] Compared with the prior art, the underground structure permanent and temporary combined support system and the construction method have the beneficial effects that: the permanent structure plates of the top plate and the middle plate are formed by using prefabricated plates or cast-in-place plates poured by using the modular hanging formwork, the top plate and the middle plate are poured at one time, there is no superimposed layer structure, and it is not necessary to bind steel bars and pour concrete again during back construction, thereby improving the construction efficiency; meanwhile, since the floor slab has no superimposed layer structure, it is not necessary to arrange temporary steel bars or exposed reserved tension bars on the permanent structure plate, thereby reducing the waste of steel bars and rusting, and the corbel and the waist beam are arranged in the enclosure structure, it is not necessary to drill the enclosure structure during back construction, thereby reducing the drilling workload.

[0027] During construction, the adjustable formwork is used for pouring, the formwork can be quickly erected and leveled during excavation of the foundation pit, and the over-excavation amount is small; the modular hanging formwork system is used for pouring the cast-in-place plate, and each layer of structure plate can be quickly poured during the back construction stage, thereby ensuring that it is not necessary to erect the formwork again during the second-stage floor slab construction. During pouring of the corbel, the waist beam, the first longitudinal beam and the second longitudinal beam, the vibration exhaust pipe is reserved, which facilitates vibration during subsequent structure pouring, and ensures the construction quality at the joint.

[0028] The cement-based permeable crystalline coating arranged between the crown beam and the enclosure structure can fill the space between the crown beam and the steel bars of the enclosure structure, waterproof the steel bar connecting position, improve the waterproof property, and the waterproof coiled material and the cement-based permeable crystalline coating are combined to be used, so that the waterproof weak points are solved under the premise of ensuring convenient and easy implementation of construction; the expansion waterstop rubber strip is arranged at the construction joint to solve the loose and non-tight conditions of the physical fixed waterstop strip, and the concrete pouring is easy to compact. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a plane arrangement schematic view of the roof of the underground structure permanent and temporary combined support system of the application;

[0030] Figure 2 is a plane arrangement schematic view of the middle plate of the underground structure permanent and temporary combined support system of the application;

[0031] Figure 3 is Figure 1 the underground structure permanent and temporary combined support system of the application; Figure 2 the 1-1 line section view of the underground structure permanent and temporary combined support system of the application;

[0032] Figure 4 is Figure 1 the 2-2 line section view of the underground structure permanent and temporary combined support system of the application; Figure 2

[0033] Figure 5 is Figure 3 the assembly node schematic view of the crown beam and the enclosure structure of the underground structure permanent and temporary combined support system of the application;

[0034] Figure 6 is Figure 3 the assembly node schematic view of the waist beam and the enclosure structure of the underground structure permanent and temporary combined support system of the application;

[0035] Figure 7 is Figure 3 the assembly node schematic view of the first longitudinal beam and the structure column of the underground structure permanent and temporary combined support system of the application;

[0036] Figure 8 is Figure 3 the assembly node schematic view of the second longitudinal beam and the structure column of the underground structure permanent and temporary combined support system of the application;

[0037] Figure 9 is a waterproof section schematic view of the underground structure permanent and temporary combined support system of the application;

[0038] Figure 10 is Figure 9 the enlarged schematic view of A of the underground structure permanent and temporary combined support system of the application;

[0039] Figure 11 is Figure 9 ​an enlarged schematic view of the underground structure permanent and temporary combined support system at B;

[0040] Figure 12 an enlarged schematic view of the underground structure permanent and temporary combined support system at C; Figure 9

[0041] Figure 13 an assembly schematic view of the adjustable leveling form used in the underground structure permanent and temporary combined support construction method of the present application;

[0042] Figure 14 a side view of the adjustable leveling form of Figure 13

[0043] Figure 15 an assembly schematic view of the modular formwork used in the underground structure permanent and temporary combined support construction method of the present application;

[0044] Figure 16 a 3-3 line cross-sectional view of the modular formwork of Figure 15

[0045] Figure 17 a 4-4 line cross-sectional view of the modular formwork of Figure 15

[0046] In the figure, 1, the enclosure structure, 2, the crown beam, 3, the first longitudinal beam, 4, the first transverse support, 5, the waist beam, 6, the second longitudinal beam, 7, the second transverse support, 8, the side wall, 9, the bottom plate, 10, the structure column, 101, the main column, 102, the temporary construction column, 11, the permanent structure plate, 12, the steel bar adapter, 13, the vibration exhaust pipe, 14, the micro-expansion concrete, 15, the self-compacting concrete, 16, the cement-based permeable crystalline coating, 17, the polysulfide sealant, 18, the waterproof roll material, 19, the expansion waterstop rubber strip, 20, the externally applied waterstop, 21, the grouting pipe, 22, the galvanized steel plate waterstop, 23, the concrete cushion layer, 24, the modular formwork, 25, the hoisting cable, 26, the locking facility, 27, the hoisting beam, 28, the main material, 29, the auxiliary material, 31, the adjustable leveling form, 32, the base, 33, the hydraulic jack, 34, the main furring strip, 35, the secondary furring strip, 36, the side form, 37, the movable rib plate. DETAILED DESCRIPTION

[0047] The specific embodiments of the present application are described in further detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application, but are not used to limit the scope of the present application.

[0048] A preferred embodiment of an underground structure permanent and temporary combined support system of the present application is shown in Figures 1 to 17 ​​​​As shown, the underground structure permanent-temporary combined support system comprises a surrounding structure 1, a top plate, a middle plate, a bottom plate 9 and side walls 8, the top plate, the middle plate and the bottom plate 9 are arranged in the surrounding structure 1 from top to bottom, the side walls 8 are arranged between the top plate and the middle plate and between the middle plate and the bottom plate 9, the side walls 8 are connected with the surrounding structure 1, and the side walls 8 are used for supporting the top plate and the middle plate and connecting the top plate, the middle plate and the bottom plate 9 as a whole. In this embodiment, the middle plate has only one layer, and in other embodiments, when the underground structure has multiple layers, the number of middle plates can be increased as needed, and the middle plate can also have two or three layers.

[0049] The top plate comprises a crown beam 2, a first longitudinal beam 3 and a first cross brace 4, the crown beam 2 is a closed loop structure arranged in a ring shape around the inner wall of the surrounding structure 1, the first longitudinal beam 3 extends along the length direction of the top plate, the first cross brace 4 extends along the width direction of the top plate, the first longitudinal beam 3 and the first cross brace 4 are arranged perpendicular to each other, and a plurality of first cross braces 4 are arranged along the length direction of the first longitudinal beam 3 at intervals, and a permanent structure plate 11 is arranged between adjacent two first cross braces 4.

[0050] The middle plate comprises a waist beam 5, a second longitudinal beam 6 and a second cross brace 7, the waist beam 5 is a closed loop structure arranged in a ring shape around the inner wall of the surrounding structure 1, the second longitudinal beam 6 extends along the length direction of the middle plate, the second cross brace 7 extends along the width direction of the middle plate, the second longitudinal beam 6 and the second cross brace 7 are arranged perpendicular to each other, and a plurality of second cross braces 7 are arranged along the length direction of the second longitudinal beam 6 at intervals, and a permanent structure plate 11 is arranged between adjacent two second cross braces 7.

[0051] The inner side of the crown beam 2 and the waist beam 5 is formed with a stepped structure for lapping the permanent structure plate 11. The permanent structure plate 11 is a prefabricated plate or a cast-in-place plate formed by using a modular formwork 24, the prefabricated plate can be directly made and formed in a factory, the modular formwork 24 can be cast in place by hoisting, and after casting and forming, the permanent structure plate 11 forms a floor structure. The floor does not use a laminated slab structure, only needs to be casted once, and does not need to set a formwork again during subsequent backfilling, thereby improving the efficiency.

[0052] The side walls 8 are connected between the crown beam 2 and the waist beam 5 and between the waist beam 5 and the bottom plate 9, the side walls 8 adopt a waterproof reinforced concrete structure, the side walls 8 are attached to the inner side of the surrounding structure 1 and fixedly connected with the surrounding structure 1. The side walls 8 connect the crown beam 2, the waist beam 5 and the bottom plate 9 as a whole and support the structure of the top plate and the middle plate.

[0053] The structural column 10 is arranged at the connecting position of the first longitudinal beam 3 and the first cross brace 4, and the second longitudinal beam 6 and the second cross brace 7, and is arranged in plurality along the length direction of the top plate, and corresponds to the first cross brace 4 and the second cross brace 7 one by one. The structural column 10 supports the first longitudinal beam 3 and the second longitudinal beam 6, can reduce the warping of the floor, and ensures the strength of the floor structure. The joint positions of the crown beam 2 and the first cross brace 4, and the waist beam 5 and the second cross brace 7 are further provided with a hidden beam, which can strengthen the structure of the joint position. In the embodiment, the structural column 10 includes a main column 101 and a temporary structural column 102, and the temporary structural column 102 is wrapped outside the main column 101.

[0054] The first waterproof structure is arranged between the crown beam 2 and the enclosure structure 1, and between the waist beam 5 and the enclosure structure 1, the second waterproof structure is arranged on the construction joint of the side wall 8, and the third waterproof structure is arranged on the construction joint of the top plate, the middle plate and the bottom plate 9. The first waterproof structure, the second waterproof structure and the third waterproof structure form the waterproof structure of the entire supporting system, reduce the water channeling gap and channel, and improve the waterproof performance.

[0055] The permanent structural plate 11 of the top plate and the middle plate is formed by a prefabricated plate or a cast-in-place plate poured by a modular formwork 24, the top plate and the middle plate are poured at one time, and do not have a superimposed layer structure, so that it is not necessary to bind steel bars and pour concrete again during the back construction, and the construction efficiency is improved; meanwhile, since the floor does not have a superimposed layer structure, it is not necessary to arrange temporary steel bars or exposed reserved reinforcing bars on the permanent structural plate 11, so that the waste of steel bars and rusting are reduced, and meanwhile, the crown beam 2 and the waist beam 5 are arranged in the enclosure structure 1, so that it is not necessary to dig the enclosure structure 1 during the back construction, and the digging workload is reduced.

[0056] During the construction, the adjustable formwork 31 is used for pouring, the formwork can be quickly erected and leveled during the excavation of the foundation pit, and the over-excavation amount is small; the modular formwork 24 system is used for pouring the cast-in-place plate, and each layer of structural plate can be quickly poured during the back construction, so that it is not necessary to erect the formwork again during the construction of the second-stage floor.

[0057] Preferably, the steel bar adapter 12 is pre-embedded on the inner side of the enclosure structure 1, and the steel bars in the crown beam 2 and the steel bars in the waist beam 5 are fixedly connected with the steel bar adapter 12.

[0058] The steel bar adapter 12 is pre-set in the enclosure structure 1, and the crown beam 2, the waist beam 5 and the steel bars of the enclosure structure 1 are connected through the steel bar adapter 12, so that the crown beam 2, the waist beam 5 and the enclosure structure 1 form an integral whole, and the structural strength is increased.

[0059] Preferably, the vibration exhaust pipe 13 is pre-set in the crown beam 2, the waist beam 5, the first longitudinal beam 3 and the second longitudinal beam 6.

[0060] The foundation pit is excavated from top to bottom in sequence, the vibration exhaust pipe 13 is pre-set in the crown beam 2, the waist beam 5, the first longitudinal beam 3 and the second longitudinal beam 6, so as to facilitate vibration during subsequent structure pouring and ensure construction quality at the joint. The position of the side wall 8 in contact with the crown beam 2, the waist beam 5 and the bottom plate 9 is poured with micro-expansion concrete 14 and self-compacting concrete 15, so as to ensure reliable pouring and compaction of the joint.

[0061] Preferably, the first waterproof structure comprises a cement-based penetrating crystalline coating 16 arranged between the end face of the crown beam 2 and the inner wall of the enclosure 1, and polythionous sealant 17 arranged at the upper and lower ends of the cement-based penetrating crystalline coating 16.

[0062] The cement-based penetrating crystalline coating 16 as a sealing material can fill the space between the crown beam 2 and the reinforcement of the enclosure 1, waterproof the reinforcement connection position, improve waterproofness, and combine the waterproofing membrane 18 with the cement-based penetrating crystalline coating 16 to solve the waterproof weak point under the premise of ensuring convenient and easy implementation of construction.

[0063] Under normal circumstances, the outside of the crown beam 2 is covered with a complete waterproofing membrane 18 for waterproofing, but since the crown beam 2 of the roof and the enclosure 1 are connected by reinforcement and reinforcement connectors 12, the reinforcement range cannot be applied with a waterproofing membrane 18. The cement-based penetrating crystalline coating 16 is used as a waterproofing measure to fill the gap between the crown beam 2 and the enclosure 1, greatly reducing water leakage pores and channels, and canceling the geotextile and plain concrete protective layer, which is beneficial to energy saving and emission reduction.

[0064] Preferably, the second waterproof structure comprises an expansion waterproof glue strip 19 and an externally attached waterproofing tape 20, the externally attached waterproofing tape 20 is attached to the outside of the construction joint, the construction joint of the side wall 8 is pre-buried with a grouting pipe 21, and the expansion waterproof glue strip 19 is arranged on the inner and outer sides of the grouting pipe 21.

[0065] The expansion waterproof glue strip 19 can solve the problem of loose and non-dense adhesion of the physical fixed waterproof strip, and is easy to pour and compact the concrete. The externally attached waterproofing tape 20 is attached to the outside of the construction joint, which can seal the construction joint from the outside. The construction joint of the side wall 8 is pre-buried with a grouting pipe 21, which facilitates the pouring of micro-expansion concrete 14 and self-compacting concrete 15 from the grouting pipe 21.

[0066] Preferably, the third waterproof structure comprises an expansion waterproof glue strip 19 and a galvanized steel plate waterproofing tape 22, the galvanized steel plate waterproofing tape 22 is arranged through the construction joint, the expansion waterproof glue strip 19 is arranged on the inner and outer sides of the galvanized steel plate waterproofing tape 22, and the externally attached waterproofing tape 20 is further arranged on the outside of the construction joint.

[0067] The third waterproof structure is formed by arranging the expansion waterproof rubber strip 19 and the galvanized steel plate waterproof belt 22 on the construction joints of the top plate, the middle plate and the bottom plate 9, the two ends of the galvanized steel plate waterproof belt 22 are bent and located on the two sides of the construction joint, and the concrete pouring is easy to be dense. The expansion waterproof rubber strip 19 can solve the loose and non-dense situation of the physical fixed waterproof strip, and the concrete pouring is easy to be dense.

[0068] Preferably, the waterproof coiled material 18 is arranged between the corbel 2 and the enclosure 1, between the waist beam 5 and the enclosure 1, between the side wall 8 and the enclosure 1, and between the bottom plate 9 and the enclosure 1, and the waterproof coiled material 18 is arranged in lap joint and closed loop.

[0069] The waterproof coiled material 18 is used in combination with the permeable crystalline layer to solve the weak waterproof point under the premise of ensuring convenient and easy implementation. In the embodiment, the waterproof coiled material 18 adopts a high polymer self-adhesive film waterproof coiled material 18, the waterproof coiled material 18 at the construction joint is overlapped, a closed loop can be formed, and the weak waterproof point is reduced. During construction, the waterproof coiled material 18 is sealed and closed at the joint with the enclosure 1, can be tightly engaged with the main structure, and the water channeling gap and channel are reduced.

[0070] The application also provides a permanent and temporary combined supporting construction method of an underground structure, which adopts the underground structure permanent and temporary combined supporting system in the above technical scheme and comprises the following steps: step one, embedding and arranging the steel bar connector 12 in the enclosure 1, excavating a foundation pit, excavating the foundation pit to the design elevation of the corbel 2, erecting an adjustable flat formwork 31 as a construction formwork, arranging a first waterproof structure between the corbel 2 and the enclosure 1, arranging a third waterproof structure at the construction joint of the top plate, presetting the vibration exhaust pipe 13 and the steel bar connector 12 below the corbel 2, the first longitudinal beam 3 and the first transverse support 4, and pouring and forming the corbel 2, the first longitudinal beam 3 and the first transverse support 4;

[0071] Step two, continuing to excavate to the design elevation of the waist beam 5, erecting an adjustable flat formwork 31 as a construction formwork, pouring and forming the waist beam 5, the second longitudinal beam 6 and the second transverse support 7, presetting the vibration exhaust pipe 13 and the steel bar connector 12 below the waist beam 5 and the second longitudinal beam 6, arranging a third waterproof structure at the construction joint of the middle plate, pouring the side wall 8 and the structural column 10;

[0072] Step three, excavating the foundation pit to the height of the bottom plate 9, entering the back construction stage, arranging the waterproof coiled material 18 after first laying a concrete cushion 23, arranging a second waterproof structure at the construction joint of the side wall 8, arranging a third waterproof structure at the construction joint of the bottom plate 9, and pouring and forming the bottom plate 9, the side wall 8 and the structural column 10;

[0073] Step four, installing the modular hanging formwork 24 with the first support and the second support as fulcrums, and pouring and forming the cast-in-place plate on site as the permanent structure plate 11 by using the modular hanging formwork 24 as a formwork; or hoisting the prefabricated plate as the permanent structure plate 11.

[0074] In this embodiment, in step one, at the connecting joint of the crown beam 2 and the enclosure 1, the base surface of the enclosure 1 is first ground with the original slurry, then the cement-based capillary crystalline coating 16 is applied, and after it is solidified, the adhesive is applied, the waterproof coiled material 18 is overlapped and closed, and after the waterproof coiled material 18 is overlapped to form a closed loop, the side wall 8 can be poured.

[0075] In step two, at the connecting joint of the waist beam 5 and the enclosure 1, the base surface of the enclosure 1 is first ground with the original slurry, then the cement-based capillary crystalline coating 16 is applied, and after it is solidified, the adhesive is applied, the waterproof coiled material 18 is overlapped and closed, and after the waterproof coiled material 18 is overlapped to form a closed loop, the side wall 8 can be poured.

[0076] In step three, when the number of middle plates is at least two layers, step two is repeated, and the excavation is continued to the height of the bottom plate 9. When arranging the waterproof coiled material 18, the waterproof coiled material 18 is wound to the construction joint of the bottom plate 9 as an overlapping part, and then the bottom plate 9 is poured.

[0077] In step four, the modular hanging formwork 24 is composed of a hanging rope 25, a locking device 26, a hanging beam 27, a main material 28, and an auxiliary material 29. The main material 28 and the auxiliary material 29 are both I-beams. When the modular hanging formwork 24 is used as a formwork for in-situ pouring and forming a cast-in-place plate, the modular hanging formwork 24 is a module every 3m, and the whole hanging formwork is installed, and then the length is adjusted through the hanging rope 25.

[0078] The installation and use process of the modular hanging formwork 24 is as follows: the main material 28-auxiliary material 29-formwork standard block is a standard module, the width of each standard module is 3m, and the length can be adjusted according to the actual project by increasing or decreasing the main material 28; during the backfilling stage, since the side wall 8, the first horizontal support 4 and the second horizontal support 7 serving as a floor have been poured, the first horizontal support 4 and the second horizontal support 7 can serve as supports of the modular hanging formwork 24; the modular hanging formwork 24 is a standard module and is directly installed and supported on the first horizontal support 4 and the second horizontal support 7.

[0079] Preferably, in steps one and two, the adjustable flat formwork 31 is used by first excavating the foundation pit to below the top plate or the middle plate, then sequentially assembling the base 32, the hydraulic jack 33, the main furring 34 and the secondary furring 35 from bottom to top, connecting the hydraulic jack 33 between the main furring 34 and the secondary furring 35, installing the side form 36 and the movable rib plate 37 on the secondary furring 35, moving the side form 36 to the set position by using the movable rib plate 37, adjusting the flatness by the jack after assembling each formwork, and then pouring.

[0080] In the embodiment, the foundation pit is excavated to about 0.8 m below the top plate or the middle plate, the base 32 is erected, the secondary keel 35 is a modular product, the material of the secondary keel 35 is a channel steel, the material of the main keel 34 is an I-beam, the first longitudinal beam 3 and the second longitudinal beam 6 can be spliced according to the cross-sectional size, and the spliced joints are fixed by bolts. The movable rib plate 37 is a steel structure, and the movable rib plate 37 is fixedly connected with the secondary keel 35 through a bolt.

[0081] Preferably, in step four, after the permanent structure plate 11 of the top plate is assembled, the original slurry is smoothed, the non-solidified rubber asphalt waterproof coating is applied first, the self-adhesive modified asphalt waterproof roll is laid, and the joint between the self-adhesive modified asphalt waterproof roll and the enclosure structure 1 is sealed and closed.

[0082] In summary, the underground structure permanent and temporary combined support system and construction method provided by the embodiment of the application has the advantages that the permanent structure plates of the top plate and the middle plate are formed by prefabricated plates or cast-in-place plates formed by a modular formwork pouring system, the top plate and the middle plate are poured at one time without a superimposed layer structure, re-bonding of steel bars and pouring of concrete are not required during back pouring, and the construction efficiency is improved. Meanwhile, since the floor slab does not have a superimposed layer structure, temporary steel bars or exposed reserved tension bars do not need to be arranged on the permanent structure plates, the waste of steel bars and rusting are reduced, the corbel and the waist beam are arranged in the enclosure structure, the enclosure structure does not need to be chiseled during back pouring, and the chiseling workload is reduced.

[0083] During construction, the adjustable leveling formwork is used for pouring, the formwork can be quickly erected and leveled during excavation of the foundation pit, and the overbreak is small. The modular formwork system is used for pouring the cast-in-place plate, the structure plates of each layer can be quickly poured during back pouring, and the formwork does not need to be erected again during the construction of the second-stage floor slab. During pouring of the corbel, the waist beam, the first longitudinal beam and the second longitudinal beam, the vibration exhaust pipe is reserved, which facilitates vibration during subsequent structure pouring, and ensures the construction quality at the joint.

[0084] The cement-based penetrating crystalline coating is arranged between the corbel and the enclosure structure, which can fill the space between the steel bars of the corbel and the enclosure structure, waterproof the connection position of the steel bars, improve the waterproof property, and combine the waterproof roll and the cement-based penetrating crystalline coating to solve the weak waterproof point under the premise of ensuring convenient and easy implementation of construction. The expansion waterproof adhesive tape is arranged at the construction joint to solve the loose and non-tight conditions of the physically fixed waterproof tape, and the concrete can be easily poured and compacted.

[0085] The above only describes the preferred embodiments of the application, and it should be noted that, for ordinary skilled persons in the technical field, several improvements and replacements can be made without departing from the technical principles of the application, and these improvements and replacements should be considered as the protection scope of the application.

Claims

1. A method for constructing a permanent-temporary combined support of an underground structure, using a permanent-temporary combined support system of the underground structure, the permanent-temporary combined support system of the underground structure comprising an enclosure, a top plate, a middle plate and a bottom plate being arranged in the enclosure from top to bottom, and side walls being arranged between the top plate and the middle plate and between the middle plate and the bottom plate; the top plate comprising a crown beam arranged annularly around the inner wall of the enclosure, a first row of longitudinal beams and a first row of cross braces being connected in the crown beam, the first row of longitudinal beams and the first row of cross braces being arranged perpendicularly to each other, and the first row of cross braces being arranged at intervals along the length direction of the first row of longitudinal beams; the middle plate comprising a waist beam arranged annularly around the inner wall of the enclosure, a second row of longitudinal beams and a second row of cross braces being connected in the waist beam, the second row of longitudinal beams and the second row of cross braces being arranged perpendicularly to each other, and the second row of cross braces being arranged at intervals along the length direction of the second row of longitudinal beams; permanent structure plates being arranged between adjacent two first row of cross braces and between adjacent two second row of cross braces, the permanent structure plates being prefabricated plates or cast-in-situ plates formed by using a modular formwork; the side walls being connected between the crown beam and the waist beam and between the waist beam and the bottom plate, structure columns being coaxially arranged and connected between the top plate and the middle plate and between the middle plate and the bottom plate, the structure columns being arranged at the connection positions of the first row of longitudinal beams and the first row of cross braces and the second row of longitudinal beams and the second row of cross braces, and the structure columns being arranged at intervals along the length direction of the top plate; first waterproof structures being arranged between the crown beam and the enclosure, second waterproof structures being arranged on the construction joints of the side walls, and third waterproof structures being arranged on the construction joints of the top plate, the middle plate and the bottom plate; steel connectors being pre-embedded on the inner side of the enclosure, the steel bars in the crown beam and the steel bars in the waist beam being fixedly connected with the steel connectors, the first waterproof structures comprising cement-based permeable crystalline coatings, the cement-based permeable crystalline coatings being arranged between the end face of the crown beam and the inner wall of the enclosure, and polysulfide sealant being arranged at the upper and lower ends of the cement-based permeable crystalline coatings; vibration exhaust pipes being pre-arranged in the crown beam, the waist beam, the first row of longitudinal beams and the second row of longitudinal beams; the second waterproof structures comprising expansion waterproof glue strips and externally-taped waterproof belts, the externally-taped waterproof belts being pasted on the outer side of the construction joints, grouting pipes being pre-embedded at the construction joints of the side walls, and the expansion waterproof glue strips being arranged on the inner and outer sides of the grouting pipes; the third waterproof structures comprising expansion waterproof glue strips and galvanized steel plate waterproof belts, the galvanized steel plate waterproof belts being arranged through the construction joints, the expansion waterproof glue strips being arranged on the inner and outer sides of the galvanized steel plate waterproof belts, and externally-taped waterproof belts being further arranged on the outer side of the construction joints; waterproof coiled materials being further arranged between the crown beam and the enclosure, between the waist beam and the enclosure, between the side walls and the enclosure, and between the bottom plate and the enclosure, and the waterproof coiled materials being arranged in a lap joint closed loop manner. characterized in that The underground structure permanent and temporary combined support construction method comprises the following steps: step one, embedding a steel bar adapter in a surrounding structure, excavating a foundation pit, excavating the foundation pit to the design elevation of a crown beam, erecting an adjustable flat formwork as a construction formwork, arranging a first waterproof structure between the crown beam and the surrounding structure, arranging a third waterproof structure at a construction joint of a top plate, presetting a vibration exhaust pipe and the steel bar adapter below the crown beam and a first longitudinal beam, and pouring and forming the crown beam, a first cross brace and the first longitudinal beam; Step two, continuing to excavate to the design elevation of a waist beam, erecting an adjustable flat formwork as a construction formwork, pouring and forming the waist beam, a second cross brace and a second longitudinal beam, presetting a vibration exhaust pipe and the steel bar adapter below the waist beam and the second longitudinal beam, arranging a third waterproof structure at a construction joint of a middle plate, pouring a side wall and a structural column; Step three, excavating the foundation pit to the height of a bottom plate, entering a back construction stage, arranging a waterproof coiled material after first constructing a concrete cushion layer, arranging a second waterproof structure at a construction joint of the side wall, arranging a third waterproof structure at a construction joint of the bottom plate, and pouring and forming the bottom plate, the side wall and the structural column; Step four, installing a modular suspended formwork with the first support and the second support as fulcrums, pouring and forming a cast-in-place plate on site as a permanent structure plate by using the modular suspended formwork as a formwork, or hoisting a prefabricated plate as a permanent structure plate, after assembling the permanent structure plate of the top plate, using original slurry to smooth, first applying non-solidified rubber asphalt waterproof paint, then laying self-adhesive modified asphalt waterproof coiled material, and sealing and closing the joint between the self-adhesive modified asphalt waterproof coiled material and the surrounding structure.

2. The permanent- temporary support construction method of an underground structure according to claim 1, wherein In step one and step two, when the adjustable flat formwork is used, the foundation pit is excavated to below the top plate or the middle plate, a base, a hydraulic jack, a main batten and a secondary batten are sequentially assembled from bottom to top, the hydraulic jack is connected between the main batten and the secondary batten, a side formwork and a movable rib plate are installed on the secondary batten, the side formwork is moved to a set position by using the movable rib plate, after assembling each formwork, the formwork is leveled by the jack, and pouring is implemented.

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