CN114809015B - Temporary support system and permanent structure combined construction method for open cut subway station - Google Patents

Abstract

The invention discloses a construction method combining a temporary support system and a permanent structure of an open-cut subway station. The construction steps include the following steps: constructing a surrounding pile machine structure for a foundation pit; excavating a part of the foundation pit; and excavating the entire foundation pit; Lay the underlayment and waterproof layer. The subway station built by the cut-and-open method provides a green design concept of "integration of eternal and temporary", which combines the traditional temporary support system of the enclosure structure with the permanent structure of the station using the method of "prefabrication + cast-in-place". A new type of station superimposed structure system was constructed, which can effectively solve many problems and disadvantages in the traditional technology, such as the waste of temporary internal support components after dismantling, the inability of the retaining piles to play a later role, and the serious environmental pollution of machinery and mud during foundation pit construction. , and avoid the risk of foundation pit instability caused by the removal of supports, it is a green and safe structural design system, which has strong applicability in the construction practice process.

Description

A combined construction method of a temporary support system and a permanent structure for an open-cut subway station

technical field

The invention relates to the technical field of building structures, in particular to a construction method combining a temporary support system and a permanent structure of an open-cut subway station.

Background technique

At present, the foundation pit support structure of subway open-cut stations in China is relatively simple, mainly based on the traditional "poured enclosure pile" as the typical representative pile support system or pile-anchor system, and the open-cut enclosure structure is generally bored For cast-in-place piles, occlusal cast-in-place piles or ground connection walls, the temporary internal support system includes horizontal horizontal supports and vertical supports, of which the horizontal horizontal supports mainly include reinforced concrete supports, steel pipe supports, section steel supports, horizontal tie beams, etc. Concrete support with a longitudinal spacing of 6-9m is set at the height of the crown beam of the retaining pile, and the rest are steel supports. 2-3 lines are set according to the vertical excavation height of the foundation pit. The vertical support is mainly steel lattice columns, and the horizontal connection The beam connects the horizontal support and the lattice column to form an overall internal support system. During the construction period, together with the enclosure structure, it resists the lateral load of the external rock mass, soil mass and water pressure, ensuring the stability and safety of the foundation pit support. .

However, in the above-mentioned construction methods, the internal support system is used as a temporary support component, and will be completely dismantled later. After the main secondary lining structure of the station is completed, the foundation pit enclosure and support system loses its original function in most cases. It can be said that the foundation pit support system of the traditional construction method The concept of protection is the idea of "eternal separation". At the same time, there are many problems and disadvantages in this traditional construction method, such as slow drilling speed, easy hole collapse, high cost, long construction period, waste of resources caused by the demolition of temporary structures later, mud The environmental pollution caused by mechanical noise and mechanical noise is relatively serious. For this reason, a construction method combining temporary support system and permanent structure of open-cut subway station is proposed.

Contents of the invention

(1) Solved technical problems

Aiming at the deficiencies of the prior art, the present invention provides a construction method combining a temporary support system and a permanent structure of an open-cut subway station to solve the problems raised in the above-mentioned background technology.

(2) Technical solution

In order to achieve the above purpose, the present invention provides the following technical solutions: a construction method combining temporary support system and permanent structure of an open-cut subway station, including 0-medium and low-strength mixed grout, 1-prefabricated pile, 2-structure lining side wall , 3-Rebar connector, 4-Crown beam of cast-in-place structure, 5-(1)-Prefabricated thin-slab unit, 5-(2)-Cast-in-place horizontal horizontal support, 6-Post-cast structural roof, 7-(1) Pre-cast Top longitudinal beam, 7-(2) Post-cast roof longitudinal beam, 8-(1) Prefabricated column core, 8-(2) Outsourcing cast-in-place layer, 9-Temporary steel pipe support, 10-Drilled concrete pile, 11- Steel connecting beam channel steel composite structure, 12-main body bottom plate and bottom longitudinal beam structure, 13-main body mid-plate and middle longitudinal beam structure, the construction steps include the following:

S01. The surrounding pile structure of the construction foundation pit;

S02. Partial excavation of foundation pit;

S03. Excavation of the foundation pit as a whole;

S04, laying cushion and waterproof layer;

S05. Superimposed pouring after dismantling and connection;

S06. The formed "prefabricated + cast-in-place" composite beam-slab permanent structure system;

S07. Backfill the top of the roof with soil to restore road traffic.

Preferably, according to what is proposed in step S01, construct the outside water-stop curtain of the foundation pit, then excavate the foundation pit to the bottom elevation of the cast-in-place structure crown beam 4, and start construction of the foundation pit surrounding protection pile structure;

When implemented:

Prefabricated pile 1 and prefabricated column core 8-(1) are prefabricated in batches in the factory in advance. During the production process of the components, the steel bar connector 3 is pre-embedded in advance, and then the prefabricated components are transported to the construction site, and the drilling of the surrounding protection piles is completed. Finally, the prefabricated pile 1 and the prefabricated column core 8-(1) are accurately lowered into the borehole through mechanical hoisting and the pick-up pile positioning platform, and the gap between the borehole wall and the prefabricated pile 1 is poured uniformly from bottom to top. A mixed slurry of medium and low strength 0;

The gap between the borehole wall and the prefabricated column core 8-(1) is poured with C25 and above-strength concrete at the length below the longitudinal beam of the floor to form a bored concrete pile 10 to form an embedded end;

The gap between the borehole wall and the prefabricated column core 8-(1) is backfilled with coarse sand over the length above the longitudinal beam of the bottom plate.

Preferably, according to the proposal in step S02, after the construction of the prefabricated pile 1 and the prefabricated column core 8-(1) is completed, the cast-in-place horizontal horizontal support 5-(2) and the first poured roof longitudinal beam 7-(1) are Position and set out the line, start partial excavation of the foundation pit, until the excavation reaches the design elevation of the above-mentioned supports and longitudinal beams, lay a thin cushion, and then process the connection of the prefabricated column core 8-(1) top steel bar joints, bind the above-mentioned supports and cast-in-place For the reinforcement of the structural crown beam 4, the concrete of the above components is finally poured as a whole to form the cast-in-place horizontal horizontal support 5-(2), the top longitudinal beam 7-(1) and the prefabricated column core 8-(1) in the construction stage Rigidly connected internal support combination system.

Preferably, according to the proposal in step S03, the excavation of the foundation pit is continued from top to bottom until the bottom of the foundation pit, and the second and third temporary steel pipe supports 9 and steel connecting beam and channel steel combined structure 11 are erected respectively until Complete the entire foundation pit support system. At the same time, when the foundation pit is excavated close to the prefabricated pile 1, the medium and low-strength mixed grout 0 wrapped inside the prefabricated pile 1 is manually removed, so that the superimposed contact surface of the pile wall and the steel connector 3 exposed.

Preferably, according to the proposal in step S04, the main bottom plate and the bottom longitudinal beam structure 12 are poured, the third temporary steel pipe support 9 is removed, and the formwork support system is set up, and the prefabricated pile 1 and the inner structure The lining side wall 2 is superimposed to form a superimposed wall, and the prefabricated column core 8-(1) is superimposed with the outsourcing cast-in-place layer 8-(2) to form a superimposed column;

The combination of the above-mentioned laminated walls, laminated columns, the main body middle plate and the middle longitudinal beam structure 13 forms a negative two-story frame structure system;

The specific lamination process is as follows:

①. The height range of the negative second floor of the prefabricated column core 8-(1) is chiseled and cleaned and the steel bars are spliced and connected, and it is poured and superimposed with the column core outsourcing cast-in-place layer 8-(2);

②. The joint surface of the inner lining side wall 2 of the negative second floor structure and the prefabricated pile 1 is the rough surface of the concave storage tank, and its concave-convex depth is greater than 6mm, and it is cleaned. pouring stack;

The above-mentioned laminated wall, laminated column, main body middle plate and middle longitudinal beam structure 13 are completed by cast-in-place;

The embedded anchor of the prefabricated column core 8-(1) is HPB300 steel bar with a diameter of 8-12mm, which needs to be bent into the concrete protective layer during the prefabrication stage. The concrete protective layer is chiseled off, and the pre-embedded anchor bar is straightened and connected with the vertical stress steel bar of the outsourcing post-casting layer 8-(2).

Preferably, according to what is proposed in step S05, the second temporary steel pipe support 9 is removed, and the side walls 2 of the inner structure on both sides of the negative first floor of the station are connected with the prefabricated piles 1 through the steel connectors 3 and then poured to form a laminated wall. The upper end of the wall is provided with side wall corbels, and the prefabricated column core 8-(1) on the negative floor is poured and superimposed with the outsourcing cast-in-place layer 8-(2) to form a superimposed column. The superimposed process is the same as that in step S04 same.

Preferably, according to the proposal in step S06, the prefabricated thin plate unit 5-(1) is laid longitudinally and continuously on the roof, and the two ends are respectively erected on the upper corbel of the structural lining wall 2 and the first poured top longitudinal beam 7-(1) side corbel Legs, the above-mentioned corbels are used as the supporting hinge joints of the prefabricated thin-slab unit 5-(1), and the prefabricated thin-slab unit 5-(1) is used as the bottom formwork of the upper post-cast layer and also serves as a part of the permanent roof, laying and binding the post-cast structural roof 6 , After pouring the stressed steel bars of the roof longitudinal beam 7-(2), and after the rough surface of the prefabricated structure and the post-cast structure is chiseled, the concrete is continuously poured in layers to form a prefabricated thin-slab unit 5-(1) The "prefabricated + cast-in-place" composite beam-slab permanent structure system is composed of components such as the roof longitudinal beam 7-(1) poured first, the roof longitudinal beam 7-(2) poured later, and the structural roof plate 6 cast afterward.

Preferably, according to the proposals in steps S01 and S02, the open-cut subway station adopts the "enclosure pile + internal support" system, and this kind of superimposed structure system needs to be in the geological rock layer or soil layer.

Preferably, the thickness dimension of the prefabricated thin plate unit 5-(1) is within 1.5 times of the height dimension of the top plate, and the width dimension of the prefabricated plate is within 1/3 of the distance dimension of the transverse support.

(3) Beneficial effects

Compared with the prior art, the present invention provides a construction method combining a temporary support system and a permanent structure of an open-cut subway station, which has the following beneficial effects:

1. The present invention provides a green design concept of "integration of permanent and temporary" for the subway station built by the open-cut method, which adopts the "prefabricated + cast-in-place" combination of the traditional temporary support system of the enclosure structure and the permanent structure of the station Methods Combining technology, a new type of station superimposed structure system is constructed, which can effectively solve the waste of temporary internal support components in the traditional technology, the enclosure piles cannot play the role in the later stage, and the machinery and mud environment pollution during foundation pit construction is serious It is a green and safe structural design system that has strong applicability in the construction practice process.

2. This invention adopts a new superimposed structure system of "combination of temporary support system and permanent structure", which is a fast, safe and efficient construction method. Prefabricated piles, prefabricated column cores, prefabricated slabs and other components are all produced in factory batches. It is not subject to cross-interference from construction sites and professions, and the work efficiency is greatly improved. Compared with traditional technical construction methods, the construction of prefabricated composite piles generally saves 40-50% of the construction period. Prefabricated thin slabs replace the unified full-hole buckle formwork support system, which is safe and can ensure the apparent quality of concrete. The operating time can save about 8-15 %, the superimposed structure system reduces the loss of manpower and working hours, saves time and space, saves cost, and has good economy.

3. The construction procedure of the present invention is clear, the operation is simple, and the implementability is strong under the condition that the underground water level is not high in the open-cut subway station.

Description of drawings

Fig. 1 is a schematic diagram of the steps of the method of the present invention;

Fig. 2 is the overall schematic diagram of the new composite structure system of "temporary support system and permanent structure superposition" of the station of the present invention;

Fig. 3 is a partial schematic diagram of the station's horizontal horizontal support, roof and top longitudinal beam "perpetually superimposed" in the present invention;

Fig. 4 is a schematic diagram of the connection structure between the prefabricated pile and the main side wall of the superimposed steel bar of the present invention;

Fig. 5 is a schematic diagram of the connection structure of superimposed steel bars of prefabricated slabs, post-cast roofs, roof longitudinal beams and other components of the present invention;

Fig. 6 is a plan view of the reinforced contact surface of the top longitudinal beam and the prefabricated column core of the present invention;

Fig. 7 is the connection construction plane between the prefabricated column core and the outsourcing post-casting layer steel bar of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The present invention provides a technical solution, as shown in Figures 1-7, a construction method for combining temporary support systems and permanent structures in open-cut subway stations, including 0-medium and low-strength mixed grout, 1-prefabricated piles, and 2-structure inner Lining side wall, 3- steel bar connector, 4- cast-in-place structure crown beam, 5-(1)- prefabricated thin plate unit, 5-(2)- cast-in-place horizontal horizontal support, 6 post-cast structure roof, 7-(1 ) first pouring roof longitudinal beam, 7-(2) post-casting roof longitudinal beam, 8-(1) prefabricated column core, 8-(2) outsourcing cast-in-place layer, 9-temporary steel pipe support, 10-drilled concrete pile , 11-steel connecting beam channel steel combined structure, 12-main body floor and bottom longitudinal beam structure, 13-main body mid-plate and middle longitudinal beam structure, the construction steps include the following:

S01. The surrounding pile structure of the construction foundation pit;

S02. Partial excavation of foundation pit;

S03. Excavation of the foundation pit as a whole;

S04, laying cushion and waterproof layer;

S05. Superimposed pouring after dismantling and connection;

S06. The formed "prefabricated + cast-in-place" composite beam-slab permanent structure system;

S07. Backfill the top of the roof with soil to restore road traffic.

Preferably, according to what is proposed in step S01, construct the outside water-stop curtain of the foundation pit, then excavate the foundation pit to the bottom elevation of the cast-in-place structure crown beam 4, and start construction of the foundation pit surrounding protection pile structure;

When implemented:

Prefabricated pile 1 and prefabricated column core 8-(1) are prefabricated in batches in the factory in advance. During the production process of the components, the steel bar connector 3 is pre-embedded in advance, and then the prefabricated components are transported to the construction site, and the drilling of the surrounding protection piles is completed. Finally, the prefabricated pile 1 and the prefabricated column core 8-(1) are accurately lowered into the borehole through mechanical hoisting and the pick-up pile positioning platform, and the gap between the borehole wall and the prefabricated pile 1 is poured uniformly from bottom to top. A mixed slurry of medium and low strength 0;

The gap between the borehole wall and the prefabricated column core 8-(1) is poured with C25 and above-strength concrete at the length below the longitudinal beam of the floor to form a bored concrete pile 10 to form an embedded end;

The gap between the borehole wall and the prefabricated column core 8-(1) is backfilled with coarse sand over the length above the longitudinal beam of the bottom plate.

Preferably, according to the proposal in step S02, after the construction of the prefabricated pile 1 and the prefabricated column core 8-(1) is completed, the cast-in-place horizontal horizontal support 5-(2) and the first poured roof longitudinal beam 7-(1) are Position and set out the line, start partial excavation of the foundation pit, until the excavation reaches the design elevation of the above-mentioned supports and longitudinal beams, lay a thin cushion, and then process the connection of the prefabricated column core 8-(1) top steel bar joints, bind the above-mentioned supports and cast-in-place For the reinforcement of the structural crown beam 4, the concrete of the above components is finally poured as a whole to form the cast-in-place horizontal horizontal support 5-(2), the top longitudinal beam 7-(1) and the prefabricated column core 8-(1) in the construction stage Rigidly connected internal support combination system.

Preferably, according to the proposal in step S03, the excavation of the foundation pit is continued from top to bottom until the bottom of the foundation pit, and the second and third temporary steel pipe supports 9 and steel connecting beam and channel steel combined structure 11 are erected respectively until Complete the entire foundation pit support system. At the same time, when the foundation pit is excavated close to the prefabricated pile 1, the medium and low-strength mixed grout 0 wrapped inside the prefabricated pile 1 is manually removed, so that the superimposed contact surface of the pile wall and the steel connector 3 exposed.

Preferably, according to the proposal in step S04, the main bottom plate and the bottom longitudinal beam structure 12 are poured, the third temporary steel pipe support 9 is removed, and the formwork support system is set up, and the prefabricated pile 1 and the inner structure The lining side wall 2 is superimposed to form a superimposed wall, and the prefabricated column core 8-(1) is superimposed with the outsourcing cast-in-place layer 8-(2) to form a superimposed column;

The combination of the above-mentioned laminated walls, laminated columns, the main body middle plate and the middle longitudinal beam structure 13 forms a negative two-story frame structure system;

The specific lamination process is as follows:

①. The height range of the negative second floor of the prefabricated column core 8-(1) is chiseled and cleaned and the steel bars are spliced and connected, and it is poured and superimposed with the column core outsourcing cast-in-place layer 8-(2);

②. The joint surface of the inner lining side wall 2 of the negative second-story structure and the prefabricated pile 1 is a rough surface of the concave storage tank to enhance the bonding force of the old and new concrete and ensure the joint force. The stressed steel bar is connected with the prefabricated pile 1 through the steel bar connector 3 and poured and stacked;

The above-mentioned laminated wall, laminated column, main body middle plate and middle longitudinal beam structure 13 are completed by cast-in-place;

The embedded anchor of the prefabricated column core 8-(1) is HPB300 steel bar with a diameter of 8-12mm, which is easy to bend. It needs to be bent into the concrete protective layer during the prefabrication stage, and the construction column core is covered with the cast-in-place layer 8-(2 ), the concrete protective layer should be chiseled off, and the pre-embedded anchor bar should be straightened and connected and anchored with the vertical stressed steel bar of the outsourcing post-casting layer 8-(2).

Preferably, according to what is proposed in step S05, the second temporary steel pipe support 9 is removed, and the side walls 2 of the inner structure on both sides of the negative first floor of the station are connected with the prefabricated piles 1 through the steel connectors 3 and then poured to form a laminated wall. The upper end of the wall is provided with side wall corbels, and the prefabricated column core 8-(1) on the negative floor is poured and superimposed with the outsourcing cast-in-place layer 8-(2) to form a superimposed column. The superimposed process is the same as that in step S04 same.

Preferably, according to the proposal in step S06, the prefabricated thin plate unit 5-(1) is laid longitudinally and continuously on the roof, and the two ends are respectively erected on the upper corbel of the inner lining wall 2 and the side corbel of the first poured roof longitudinal beam 7-(1) , the above-mentioned corbel is used as the supporting hinge node of the prefabricated thin-slab unit 5-(1), and the prefabricated thin-slab unit 5-(1) is used as the bottom formwork of the upper post-cast layer and also serves as a part of the permanent roof, and the post-cast structural roof 6 is laid and tied. After pouring the reinforced steel bars of the roof longitudinal beam 7-(2), and after the rough surface of the prefabricated structure and the post-cast structure is chiseled, the concrete is continuously poured in layers to form a prefabricated thin-slab unit 5-(1), The "prefabricated + cast-in-place" composite beam-slab permanent structural system is composed of components such as the roof longitudinal girder 7-(1) poured later, the roof longitudinal girder 7-(2) poured later, and the structural roof plate 6 cast afterward. full load.

Preferably, according to the proposals in steps S01 and S02, the open-cut subway station adopts the "enclosure pile + internal support" system, and this kind of superimposed structure system needs to be in the geological rock layer or soil layer.

Preferably, the thickness of the prefabricated thin-slab unit 5-(1) is within 1.5 times the height of the roof, and the width of the prefabricated slab is within 1/3 of the distance between the lateral supports. The weight of components can be reduced to a minimum, which is convenient for mechanical hoisting. In order to control deflection and deformation, prefabricated panels can be prefabricated components with a certain prestress.

The working principle of this device: Firstly, the open-cut subway station adopts the support system of "surrounding pile + internal support" in the foundation pit support scheme according to the characteristics of the stratum. The temporary support combination system in the construction stage is mainly: medium and low strength mixed grout 0. Prefabricated pile 1. Cast-in-place horizontal horizontal support 5-(2), first-cast roof longitudinal beam 7-(1), prefabricated column core 8-(1) drilled and poured concrete pile 10 and other components for temporary support during the construction stage The protection combination system will not be dismantled in the later stage, but will be used as a part of the permanent structure. After being superimposed with the post-cast structure, it will participate in the stress of the later use stage and play two stages at the same time. Temporary steel pipe support 9, bored concrete piles 10. Steel coupling beam channel steel composite structure 11. Each component in the composite system in the above construction stage is also a part of the permanent structure in the long-term use stage, and forms a permanent structure after being superimposed with the inner lining structure;

After the foundation pit support plan is determined, the construction enclosure and traffic relief shall be done first, and then the foundation pit excavation and support shall be carried out. The specific construction steps are as follows:

Construction step 1: first construct the water-stop curtain outside the foundation pit, then excavate the foundation pit to the bottom elevation of the cast-in-place structure crown beam 4, and start the construction of the foundation pit surrounding protection pile structure, namely: prefabricated pile 1 and prefabricated column core 8-( 1) Batch prefabricated production in the factory in advance. During the component production process, the steel bar connector 3 is pre-buried in advance, and then the prefabricated components are transported to the construction site. After the drilling of the surrounding protection piles is completed, the platform is positioned by mechanical hoisting and pick-up piles Put the prefabricated pile 1 and the prefabricated column core 8-(1) into the borehole accurately, and pour a medium-low-strength mixed grout 0 evenly from bottom to top in the gap between the wall of the borehole and the prefabricated pile 1, and drill The gap between the hole wall and the prefabricated column core 8-(1) is poured with C25 and above-strength concrete at the length below the longitudinal beam of the bottom plate to form a bored concrete pile 10 to form the embedded end, and the hole wall and the prefabricated column core 8- (1) The gaps between the bottom plate longitudinal beams are poured with coarse sand and backfilled densely;

Construction step 2: After the construction of prefabricated pile 1 and prefabricated column core 8-(1) for foundation pit enclosure is completed, the horizontal horizontal support 5-(2) and the first poured roof longitudinal beam 7-(1) are positioned and laid out, and the start Partial excavation of the foundation pit until the excavation reaches the design elevation of the above-mentioned supports and longitudinal beams, lay a thin cushion, and then process the connection of the prefabricated column core 8-(1) top steel bar joints, bind the above-mentioned supports and the steel bars of the crown beam 4, and finally Carry out the overall concrete pouring of the above components to form an internal support combination system of rigid connection of horizontal support 5-(2), longitudinal connecting beam 7-(1) and vertical support 8-(1) during the construction stage. Work together with the prefabricated pile 1 to ensure the stability and safety of foundation pit excavation;

Construction step 3: Continue excavating the foundation pit from top to bottom until the bottom of the foundation pit, erect the second and third temporary steel pipe supports 9 and the steel connecting beam channel steel composite structure 11, until the entire foundation pit support system is completed, At the same time, when the excavation of the foundation pit is close to the prefabricated pile 1, the inner side of the prefabricated pile 1 is manually covered.

The wrapped medium and low strength mixed grout 0 is chiseled off, so that the stacked contact surface of the pile wall and the steel bar connector 3 are exposed;

Construction step 4: Lay the cushion and waterproof layer, pour the main floor and the bottom longitudinal beam structure 12, remove the third temporary steel pipe support 9, set up the formwork support system, and use the "prefabricated + cast-in-place" method to connect the prefabricated pile 1 with the structure The lining side wall 2 is superimposed to form a superimposed wall, the prefabricated column core 8-(1) is superimposed with the outsourcing cast-in-place layer 8-(2) to form a superimposed column, and the above-mentioned superimposed wall, superimposed column and the main middle plate and middle Longitudinal beam structures 13 are combined to form a negative second-story frame structure system. The specific lamination process is: prefabricated column core 8-(1) within the negative second-story height range chiseling and cleaning and steel bar connection, and the column core is covered with cast-in-place layer 8 -(2) Carry out pouring and superimposition, the side wall 2 of the inner lining structure of the negative second floor and the joint surface of the prefabricated pile are chiseled and cleaned, and the reinforced steel bars of the wall are connected with the prefabricated pile 1 through the steel bar connector 3 and poured and superimposed. The above superimposed wall , The superimposed column, the main body middle plate and the middle longitudinal beam structure 13 are completed by cast-in-place method, which is beneficial to improve the seismic performance of component joints;

Construction step 5: Remove the second temporary steel pipe support 9, the side walls 2 of the structure lining on both sides of the negative floor of the station and the prefabricated piles 1 are connected through the steel connector 3 and then poured to form a laminated wall, and the upper end of the wall is provided with side wall cattle leg;

The prefabricated column core 8-(1) on the negative floor is poured and superimposed with the outsourcing cast-in-place layer 8-(2) to form a superimposed column, and the superimposed process is the same as step 4;

Construction step 6: The prefabricated thin plate unit 5-(1) is laid longitudinally and continuously on the roof, and the two ends are respectively erected on the upper corbel of the structural lining wall 2 and the side corbel of the roof longitudinal beam 7-(1). The above-mentioned corbels are used as prefabricated The supporting hinge joint of the thin-slab unit 5-(1), the prefabricated thin-slab unit 5-(1) serves as the bottom formwork of the upper post-casting layer and also serves as a part of the permanent roof, and then lays the tied post-cast structural roof 6 and the post-cast roof longitudinal Beam 7-(2) is stressed, and after the rough surface in contact with the prefabricated structure and the post-cast structure has been chiseled, the concrete is continuously poured layer by layer to form a prefabricated thin-slab unit 5-(1), and the top longitudinal Beam 7-(1), post-cast roof longitudinal beam 7-(2), post-cast structure roof 6 and other components constitute the "prefabricated + cast-in-place" laminated beam-slab permanent structure system, which jointly bears all external loads;

Construction Step 7: Backfill the top of the roof with soil to restore road traffic.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (3)

1. A construction method combining temporary support system and permanent structure of an open-cut subway station, characterized in that: 0-medium and low-strength mixed grout, 1-prefabricated pile, 2-structure lining side wall, 3-rebar connector , 4-Crown beam of cast-in-place structure, 5-(1)-Prefabricated thin-slab unit, 5-(2)-Cast-in-place horizontal horizontal support, 6. Post-cast structural roof, 7-(1) Cast-in-place top longitudinal beam, 7- (2) Post-cast roof longitudinal beam, 8-(1) prefabricated column core, 8-(2) outsourcing cast-in-place layer, 9-temporary steel pipe support, 10-drilled concrete pile, 11-steel coupling beam and channel steel combination Structure, 12-main body bottom plate and bottom longitudinal beam structure, 13-main body middle plate and middle longitudinal beam structure, the construction steps include the following: S01. The surrounding pile structure of the construction foundation pit; S02. Partial excavation of foundation pit; S03. Excavation of the foundation pit as a whole; S04, laying cushion and waterproof layer; S05. Superimposed pouring after dismantling and connection; S06. The formed "prefabricated + cast-in-place" composite beam-slab permanent structure system; S07. Backfill the top of the roof with soil to restore road traffic; According to what is proposed in step S01, construct the outer water-stop curtain of the foundation pit, then excavate the foundation pit to the bottom elevation of the cast-in-place structure crown beam 4, and start construction of the foundation pit surrounding protection pile structure; When implemented: Prefabricated pile 1 and prefabricated column core 8-(1) are prefabricated in batches in the factory in advance. During the production process of the components, the steel bar connector 3 is pre-embedded in advance, and then the prefabricated components are transported to the construction site, and the drilling of the surrounding protection piles is completed. Finally, the prefabricated pile 1 and the prefabricated column core 8-(1) are accurately lowered into the borehole through mechanical hoisting and the pick-up pile positioning platform, and the gap between the borehole wall and the prefabricated pile 1 is poured uniformly from bottom to top. A mixed slurry of medium and low strength 0; The gap between the borehole wall and the prefabricated column core 8-(1) is poured with C25 and above-strength concrete at the length below the longitudinal beam of the floor to form a bored concrete pile 10 to form an embedded end; The gap between the wall of the borehole and the prefabricated column core 8-(1) is filled with coarse sand and backfilled in the length above the longitudinal beam of the bottom plate; According to the proposal in step S02, after the construction of prefabricated pile 1 and prefabricated column core 8-(1) is completed, the cast-in-place horizontal horizontal support 5-(2) and the pre-cast top longitudinal beam 7-(1) are positioned and laid out , start partial excavation of the foundation pit until the excavation reaches the design elevation of the above-mentioned supports and longitudinal beams, lay a thin cushion, and then process the connection of the prefabricated column core 8-(1) top steel bar joints, bind the above-mentioned supports and the cast-in-place structure crown beam 4 steel bars, and finally carry out the overall concrete pouring of the above components to form the cast-in-place horizontal horizontal support 5-(2), the roof longitudinal beam 7-(1) and the prefabricated column core 8-(1) rigidly connected during the construction stage Internal support combination system; According to the proposal in step S03, the foundation pit excavation is continued from top to bottom until the bottom of the foundation pit, and the second and third temporary steel pipe supports 9 and the steel connecting beam channel steel composite structure 11 are erected respectively until the entire foundation is completed. At the same time, when the foundation pit is excavated close to the prefabricated pile 1, the medium and low-strength mixed grout 0 wrapped inside the prefabricated pile 1 is manually removed, so that the superimposed contact surface of the pile wall and the steel connector 3 are exposed; According to the proposal in step S04, the main floor and the bottom longitudinal beam structure 12 are poured, the third temporary steel pipe support 9 is removed, and the formwork support system is set up, and the prefabricated pile 1 and the structure lining side wall are adopted in the "prefabricated + cast-in-place" method 2. Laminated to form a laminated wall, the prefabricated column core 8-(1) is laminated with the outsourcing cast-in-place layer 8-(2) to form a laminated column; The combination of the above-mentioned laminated walls, laminated columns, the main body middle plate and the middle longitudinal beam structure 13 forms a negative two-story frame structure system; The specific lamination process is as follows: ①. The height range of the negative second floor of the prefabricated column core 8-(1) is chiseled and cleaned and the steel bars are spliced and connected, and it is poured and superimposed with the column core outsourcing cast-in-place layer 8-(2); ②. The joint surface of the inner lining side wall 2 of the negative second floor structure and the prefabricated pile 1 is the rough surface of the concave storage tank, and its concave-convex depth is greater than 6mm, and it is cleaned. pouring stack; The above-mentioned laminated wall, laminated column, main body middle plate and middle longitudinal beam structure 13 are completed by cast-in-place; The embedded anchor of the prefabricated column core 8-(1) is HPB300 steel bar with a diameter of 8-12mm, which needs to be bent into the concrete protective layer during the prefabrication stage. Cut off the concrete protective layer, straighten the pre-embedded anchor bar and connect and anchor it with the vertical stressed steel bar of the outsourcing post-casting layer 8-(2); According to the proposal in step S05, the second temporary steel pipe support 9 is removed, and the side walls 2 of the structure lining on both sides of the negative floor of the station are connected with the prefabricated piles 1 through the steel connector 3 and then poured to form a laminated wall. The upper end of the wall Set side wall corbels, the negative floor prefabricated column core 8-(1) is poured and superimposed with the outsourcing cast-in-place layer 8-(2) to form a superimposed column, and the superimposed process is the same as that in step S04; According to the proposal in step S06, the prefabricated thin plate unit 5-(1) is laid longitudinally and continuously on the roof, and the two ends are respectively erected on the upper corbel of the structural lining wall 2 and the side corbel of the top longitudinal beam 7-(1). The corbel acts as the supporting hinge node of the prefabricated thin-slab unit 5-(1), and the prefabricated thin-slab unit 5-(1) serves as the bottom formwork of the upper post-casting layer and also serves as a part of the permanent roof. The stressed steel bars of the top longitudinal beam 7-(2), and after the rough surface in contact with the prefabricated structure and the post-cast structure are chiseled, the concrete is continuously poured in layers to form a prefabricated thin-slab unit 5-(1), the pre-cast The "prefabricated + cast-in-place" composite beam-slab permanent structure system is composed of roof longitudinal beam 7-(1), post-cast roof longitudinal beam 7-(2), post-cast structural roof 6 and other components. 2. The construction method for combining a temporary support system and a permanent structure of an open-cut subway station according to claim 1, characterized in that: according to the proposals in steps S01 and S02, the "enclosure pile + internal support" system is adopted For open-cut subway stations, this kind of superimposed structure system needs to be in the geological rock layer or soil layer. 3. A construction method for combining temporary support system and permanent structure of an open-cut subway station according to claim 1, characterized in that: the thickness of the prefabricated thin plate unit 5-(1) is within 1.5 times the height of the roof, The width dimension of the prefabricated slab is within 1/3 of the spacing dimension of the transverse support.

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