CN111676979A

CN111676979A - Reusable foundation pit dry-type connection inner support system and construction method thereof

Info

Publication number: CN111676979A
Application number: CN202010424426.5A
Authority: CN
Inventors: 张黎飞; 邸博; 郑愚; 夏立鹏; 孙璨
Original assignee: Dongguan University of Technology
Current assignee: Dongguan University of Technology
Priority date: 2020-05-19
Filing date: 2020-05-19
Publication date: 2020-09-18
Anticipated expiration: 2040-05-19
Also published as: CN111676979B

Abstract

The invention discloses a reusable foundation pit dry-type connection inner support system and a construction method thereof, wherein the inner support system comprises a support rod assembly, an adjustable swivel head and a spring energy storage tank; the inner supporting rods of the supporting rod assembly comprise core section steel, concrete parts and FRP pipes, and a dry type connecting mechanism is arranged between every two adjacent inner supporting rods; the adjustable head comprises an adjustable head movable part, an adjustable head fixed part and a bidirectional hydraulic actuator; the spring energy storage tank comprises an energy storage tank body, an oil cylinder, a built-in oil pump, a large-stroke spring, a hydraulic adjusting actuator, an oil pressure output pipeline and a two-way oil valve; the inner support system has the advantages of novel structural design, simple construction of the inner support of the foundation pit, recycling and reuse, low use loss of the inner support and capability of realizing inner and inner adjustment of the stay bar. The construction method has the advantages of simple construction and capability of realizing the adjustment of the inner lining of the stay bar.

Description

Reusable foundation pit dry-type connection inner support system and construction method thereof

Technical Field

The invention relates to the technical field of civil engineering construction, in particular to a reusable foundation pit dry-type connection inner support system and a construction method thereof.

Background

The cast-in-place reinforced concrete inner support has the advantages of high bearing capacity, high rigidity and good integrity; however, the cast-in-place reinforced concrete inner support needs to be provided with a template for cast-in-place in the construction process, is inconvenient to dismantle, is inconvenient to construct, is long in time consumption, and is time-consuming and labor-consuming to dismantle for one-time pouring.

The steel support or the steel-concrete combined support has the advantages of high assembly and disassembly speed and the like; however, for steel supports or steel-concrete combined supports, the bearing capacity is limited, the construction difficulty of site nodes is high, the support is dense, soil is disadvantageously excavated, and the durability is poor.

From the above situation, it can be known that, for the conventional support system in the foundation pit, the following problems exist, specifically:

1. the cast-in-place reinforced concrete foundation pit inner support is difficult to construct, long in construction period, incapable of being recycled, incapable of adjusting the internal force of the stay bar and large in self weight;

2. in order to ensure that the support in the cast-in-place reinforced concrete foundation pit has better stability, a larger cross section area of the brace rod needs to be poured, and more brace rods are needed for supporting;

3. the cast-in-place reinforced concrete support needs to increase the number of supports for coordinating internal force because the internal force cannot be adjusted, so that the normal construction of a foundation pit is influenced;

4. the steel support and the steel-concrete combined support need to increase the cross section area of the support in order to ensure the stability of the support, and are not beneficial to normal construction;

5. the easy corrosion of steel seriously influences the service life of the support and needs frequent maintenance;

6. the traditional loose head can not be adjusted after the installation and positioning are finished, so that the stability of the internal force of the side wall of the foundation pit is not facilitated;

7. the traditional movable head is fixed by a wedge-shaped steel sheet, and the connection becomes unreliable along with the corrosion and the sliding of the steel sheet, so that the safety of foundation pit construction is seriously influenced.

Disclosure of Invention

The invention aims to provide a reusable foundation pit dry-type connection inner support system aiming at the defects of the prior art, which has the advantages of novel structural design, simple construction of the foundation pit inner support, cyclic reuse, low use loss of the inner support and capability of realizing the adjustment of the inner lining of a stay bar.

The invention also aims to provide a construction method of the reusable foundation pit dry-type connection inner support system, which is simple in construction and can realize the adjustment of the inner lining of the support rod.

In order to achieve the above object, the present invention is achieved by the following technical solutions.

A reusable foundation pit dry-type connection inner support system comprises a stay bar assembly, an adjustable moving head and a spring energy storage tank;

the supporting rod assembly comprises inner supporting rods which are sequentially arranged at intervals along the supporting direction of the foundation pit, each inner supporting rod comprises core section steel, a concrete part which is poured and surrounds the periphery of the core section steel and FRP pipes which are wrapped and sleeved on the periphery of the concrete part, the front end part of the core section steel protrudes and extends to the front end side of the concrete part, and the rear end part of the core section steel protrudes and extends to the rear end side of the concrete part; a dry type connecting mechanism is arranged between two adjacent inner support stay bars, the front end part of the dry type connecting mechanism is connected with the rear end part of the core section steel of the inner support stay bar at the front side, and the rear end part of the dry type connecting mechanism is connected with the front end part of the core section steel of the inner support stay bar at the rear side;

the adjustable head is positioned at one end side of the stay bar component and comprises an adjustable head movable part and an adjustable head fixing part, the adjustable head fixing part comprises a fixed tailstock and a fixed cylinder arranged on the fixed tailstock, a cylinder accommodating cavity which is opened towards the stay bar component side is formed in the fixed cylinder, and a bidirectional hydraulic actuator which moves along the supporting direction of the foundation pit is embedded in the cylinder accommodating cavity of the fixed cylinder; the movable part of the movable head comprises a movable cylinder body sleeved on the periphery of the fixed cylinder body, and the end part of the movable cylinder body, close to one side of the stay bar component, is provided with a movable head connecting flange; a section steel end flange is welded at the end part of the core section steel of the inner support stay bar close to the adjustable loose head, and the section steel end flange is connected with a loose head connecting flange through a flange screw;

the spring energy storage tank comprises an energy storage tank body, an oil storage chamber for containing hydraulic oil is arranged in the energy storage tank body, an oil cylinder, a built-in oil pump, a large stroke spring and a hydraulic adjusting actuator are arranged in the energy storage tank body, the large stroke spring is positioned between a piston of the oil cylinder and the hydraulic adjusting actuator, the piston extending end of the oil cylinder at one end of the large stroke spring is connected, and the other end of the large stroke spring is connected with the driving end of the hydraulic adjusting actuator; an oil inlet of the built-in oil pump is communicated with the oil storage cavity through an oil pipeline, an oil outlet of the built-in oil pump is communicated with an oil cavity of the oil cylinder through the oil pipeline, an oil pressure output pipeline communicated with the oil cavity of the oil cylinder is further arranged on the tank body of the energy storage tank, and the oil pressure output pipeline is provided with a two-way oil valve;

the bidirectional hydraulic actuator of the adjustable moving head is provided with a prestressed oil pump, and an oil inlet pipeline of the bidirectional hydraulic actuator, an oil outlet pipeline of the prestressed oil pump and an oil pressure output pipeline of the spring energy storage tank are connected through a three-way oil pipe; the reusable foundation pit dry-type connection inner support system is provided with an oil pressure controller, an oil inlet pipeline of the bidirectional hydraulic actuator is internally provided with a pressure sensor, and the pressure sensor, the prestressed oil pump and the built-in oil pump of the spring energy storage tank are respectively and electrically connected with the oil pressure controller; the oil inlet pipeline of the bidirectional hydraulic actuator is also provided with a valve for controlling the on-off state.

The core section steel of the inner support stay bar of the stay bar assembly is I-shaped section steel, and each I-shaped section steel connected with the dry-type connecting mechanism is provided with section steel screw holes which are sequentially arranged at intervals from front to back;

the dry type connecting mechanism comprises a middle connecting web plate, and the middle connecting web plate is provided with web plate screw holes which are sequentially arranged from front to back at intervals; the front end part of the middle connecting web plate is connected with the I-shaped section steel of the inner supporting stay bar on the front side through screws, the rear end part of the middle connecting web plate is connected with the I-shaped section steel of the inner supporting stay bar on the rear side through screws, and the screws are inserted into web plate screw holes and section steel screw holes in corresponding positions.

Wherein the intermediate connecting web is provided with reinforcing ribs.

The core section steel of the inner support stay bar of the stay bar assembly is circular section steel, at least two section steel ear plates which are uniformly distributed in the circumferential direction are welded on the outer circumferential surface of each circular section steel connected with the dry-type connecting mechanism respectively, each section steel ear plate is in a strip shape and extends along the front-back direction respectively, and each section steel ear plate is provided with ear plate screw holes which are sequentially arranged from front to back at intervals;

the dry type connecting mechanism comprises intermediate connecting webs the number of which is consistent with that of the section steel ear plates of the circular section steel, each intermediate web comprises a web main body in an arc shape, web ear plates are arranged at two longitudinal edge parts of the web main body respectively, and each web ear plate is provided with web screw holes which are sequentially arranged at intervals along the front-back direction;

the front end part of each intermediate connecting web plate extends into the space between two adjacent section steel ear plates of the inner support stay bar on the front side respectively, and the rear end part of each intermediate connecting web plate extends into the space between two adjacent section steel ear plates of the inner support stay bar on the rear side respectively; the front end part of each web plate ear plate is respectively connected with the section steel ear plate at the corresponding position of the inner support stay bar at the front side through screws, the rear end part of each web plate ear plate is respectively connected with the section steel ear plate at the corresponding position of the inner support stay bar at the rear side through screws, and each screw is respectively inserted into the ear plate screw hole and the web plate screw hole at the corresponding position.

And an optical fiber sensor is arranged inside the tube wall of the FRP tube.

The optical fiber sensor is of a crossed spiral double-helix structure, and the helix angle of the optical fiber sensor is the same as the fiber angle of the FRP pipe.

The adjusting hydraulic actuator of the spring energy storage tank is provided with an auxiliary oil pump, the auxiliary oil pump is connected with the adjusting hydraulic actuator through an oil conveying pipeline, and the auxiliary oil pump is electrically connected with the oil pressure controller.

A construction method for a reusable foundation pit dry-type connection inner support system comprises the following steps:

a. selecting the type of the inner support stay bar according to the engineering support load condition, wherein the inner support stay bar comprises core section steel, a concrete part poured and surrounded on the periphery of the core section steel and an FRP pipe wrapped on the periphery of the concrete part, the front end part of the core section steel protrudes and extends to the front end side of the concrete part, and the rear end part of the core section steel protrudes and extends to the rear end side of the concrete part; the core section steel of the inner support stay bar is I-shaped section steel or round section steel, and the end part of the core section steel of the inner support stay bar connected with the adjustable loose head is welded with a section steel end part flange;

b. selecting the length of the inner support stay bar according to the size of the engineering foundation pit;

c. transporting the inner support stay bar, the adjustable flexible head, the spring energy storage tank and the dry type connecting mechanism to a construction site;

the adjustable flexible head comprises a flexible head movable part and a flexible head fixing part, the flexible head fixing part comprises a fixed tailstock and a fixed cylinder arranged on the fixed tailstock, a cylinder accommodating cavity which is opened towards the side of the stay bar component is formed in the fixed cylinder, a bidirectional hydraulic actuator which acts along the supporting direction of the foundation pit is embedded in the cylinder accommodating cavity of the fixed cylinder, a valve used for controlling the on-off state is arranged on an oil inlet pipeline of the bidirectional hydraulic actuator, and a prestressed oil pump is assembled on the bidirectional hydraulic actuator; the movable part of the movable head comprises a movable cylinder body sleeved on the periphery of the fixed cylinder body, and the movable cylinder body is provided with a movable head connecting flange;

d. the adjustable joint is characterized in that inner support stay bars and adjustable movable joints are positioned and installed, two adjacent inner support stay bars are connected through a dry type connecting mechanism, and a section steel end flange of the inner support stay bar connected with the adjustable movable joint is connected with a movable joint connecting flange through a flange screw;

an oil inlet pipeline of the bidirectional hydraulic actuator, an oil outlet pipeline of the prestressed oil pump and an oil pressure output pipeline of the spring energy storage tank are connected through a three-way oil pipe, a pressure sensor is arranged in the oil inlet pipeline of the bidirectional hydraulic actuator, and the pressure sensor, the prestressed oil pump and the built-in oil pump of the spring energy storage tank are respectively and electrically connected with an oil pressure controller;

for the inner support stay bar with the core section steel being I-shaped section steel, the I-shaped section steel connected with the dry-type connecting mechanism is respectively provided with section steel screw holes which are sequentially arranged at intervals from front to back; the dry type connecting mechanism comprises a middle connecting web plate, the middle connecting web plate is provided with reinforcing ribs, and the middle connecting web plate is provided with web plate screw holes which are sequentially arranged at intervals from front to back; the front end part of the middle connecting web plate is connected with the I-shaped section steel of the inner support stay bar at the front side through screws, the rear end part of the middle connecting web plate is connected with the I-shaped section steel of the inner support stay bar at the rear side through screws, and the screws are inserted into web plate screw holes and section steel screw holes at corresponding positions;

for the inner support stay bar with the core section steel being the circular section steel, at least two section steel ear plates which are uniformly distributed in the circumferential direction are welded on the outer circumferential surface of each circular section steel connected with the dry-type connecting mechanism respectively, each section steel ear plate is in a strip shape and extends along the front-back direction respectively, and each section steel ear plate is provided with ear plate screw holes which are sequentially arranged from front to back at intervals; the dry type connecting mechanism comprises intermediate connecting webs the number of which is consistent with that of the section steel ear plates of the circular section steel, each intermediate web comprises a web main body in an arc shape, web ear plates are arranged at two longitudinal edge parts of the web main body respectively, and each web ear plate is provided with web screw holes which are sequentially arranged at intervals along the front-back direction; the front end part of each intermediate connecting web plate extends into the space between two adjacent section steel ear plates of the inner support stay bar on the front side respectively, and the rear end part of each intermediate connecting web plate extends into the space between two adjacent section steel ear plates of the inner support stay bar on the rear side respectively; the front end part of each web plate ear plate is respectively connected with the section steel ear plate at the corresponding position of the inner support stay bar at the front side through screws, the rear end part of each web plate ear plate is respectively connected with the section steel ear plate at the corresponding position of the inner support stay bar at the rear side through screws, and each screw is respectively inserted into an ear plate screw hole and a web plate screw hole at the corresponding positions;

e. the prestress oil pump is started through the oil pressure controller and drives the bidirectional hydraulic actuator to act so as to realize prestress loading on the inner support stay bar;

f. after the prestress loading is finished, closing a valve of an oil inlet pipeline of the bidirectional hydraulic actuator, controlling a prestress oil pump to stop acting by an oil pressure controller, and controlling a built-in oil pump of the spring energy storage tank to start by the oil pressure controller so as to carry out oil pressure balance through the spring energy storage tank; when the oil pressure value acquired by the pressure sensor deviates from a preset value, the oil pressure controller controls the built-in oil pump to act and realize pressurization or pressure relief;

g. and unloading the oil pressure after the foundation pit construction is finished, dismantling the components and clearing the site.

The fiber optic sensor is arranged inside the pipe wall of the FRP pipe, the fiber optic sensor is of a crossed spiral double-helix structure, and the helix angle of the fiber optic sensor is the same as the fiber angle of the FRP pipe.

The invention has the beneficial effects that: the invention discloses a reusable foundation pit dry-type connection inner support system, which is characterized in that: comprises a stay bar component, an adjustable flexible head and a spring energy storage tank; the supporting rod assembly comprises inner supporting rods which are sequentially arranged at intervals along the supporting direction of the foundation pit, each inner supporting rod comprises core section steel, a concrete part which is poured and surrounds the periphery of the core section steel and FRP pipes which are wrapped and sleeved on the periphery of the concrete part, the front end part of the core section steel protrudes and extends to the front end side of the concrete part, and the rear end part of the core section steel protrudes and extends to the rear end side of the concrete part; a dry type connecting mechanism is arranged between two adjacent inner support stay bars, the front end part of the dry type connecting mechanism is connected with the rear end part of the core section steel of the inner support stay bar at the front side, and the rear end part of the dry type connecting mechanism is connected with the front end part of the core section steel of the inner support stay bar at the rear side; the adjustable head is positioned at one end side of the stay bar component and comprises an adjustable head movable part and an adjustable head fixing part, the adjustable head fixing part comprises a fixed tailstock and a fixed cylinder arranged on the fixed tailstock, a cylinder accommodating cavity which is opened towards the stay bar component side is formed in the fixed cylinder, and a bidirectional hydraulic actuator which moves along the supporting direction of the foundation pit is embedded in the cylinder accommodating cavity of the fixed cylinder; the movable part of the movable head comprises a movable cylinder body sleeved on the periphery of the fixed cylinder body, and the end part of the movable cylinder body, close to one side of the stay bar component, is provided with a movable head connecting flange; a section steel end flange is welded at the end part of the core section steel of the inner support stay bar close to the adjustable loose head, and the section steel end flange is connected with a loose head connecting flange through a flange screw; the spring energy storage tank comprises an energy storage tank body, an oil storage chamber for containing hydraulic oil is arranged in the energy storage tank body, an oil cylinder, a built-in oil pump, a large stroke spring and a hydraulic adjusting actuator are arranged in the energy storage tank body, the large stroke spring is positioned between a piston of the oil cylinder and the hydraulic adjusting actuator, the piston extending end of the oil cylinder at one end of the large stroke spring is connected, and the other end of the large stroke spring is connected with the driving end of the hydraulic adjusting actuator; an oil inlet of the built-in oil pump is communicated with the oil storage cavity through an oil pipeline, an oil outlet of the built-in oil pump is communicated with an oil cavity of the oil cylinder through the oil pipeline, an oil pressure output pipeline communicated with the oil cavity of the oil cylinder is further arranged on the tank body of the energy storage tank, and the oil pressure output pipeline is provided with a two-way oil valve; the bidirectional hydraulic actuator of the adjustable moving head is provided with a prestressed oil pump, and an oil inlet pipeline of the bidirectional hydraulic actuator, an oil outlet pipeline of the prestressed oil pump and an oil pressure output pipeline of the spring energy storage tank are connected through a three-way oil pipe; the reusable foundation pit dry-type connection inner support system is provided with an oil pressure controller, an oil inlet pipeline of the bidirectional hydraulic actuator is internally provided with a pressure sensor, and the pressure sensor, the prestressed oil pump and the built-in oil pump of the spring energy storage tank are respectively and electrically connected with the oil pressure controller; the oil inlet pipeline of the bidirectional hydraulic actuator is also provided with a valve for controlling the on-off state. Through the structural design, the reusable foundation pit dry-type connection inner support system is novel in structural design, simple in foundation pit inner support construction, recyclable and reusable, low in inner support use loss and capable of achieving inner support rod inner adjustment.

The invention has the following beneficial effects: the invention relates to a construction method of a reusable foundation pit dry-type connection inner support system, which comprises the following steps: a. selecting the type of the inner support stay bar according to the engineering support load condition, wherein the inner support stay bar comprises core section steel, a concrete part poured and surrounded on the periphery of the core section steel and an FRP pipe wrapped on the periphery of the concrete part, the front end part of the core section steel protrudes and extends to the front end side of the concrete part, and the rear end part of the core section steel protrudes and extends to the rear end side of the concrete part; the core section steel of the inner support stay bar is I-shaped section steel or round section steel, and the end part of the core section steel of the inner support stay bar connected with the adjustable loose head is welded with a section steel end part flange; b. selecting the length of the inner support stay bar according to the size of the engineering foundation pit; c. transporting the inner support stay bar, the adjustable flexible head, the spring energy storage tank and the dry type connecting mechanism to a construction site; the adjustable flexible head comprises a flexible head movable part and a flexible head fixing part, the flexible head fixing part comprises a fixed tailstock and a fixed cylinder arranged on the fixed tailstock, a cylinder accommodating cavity which is opened towards the side of the stay bar component is formed in the fixed cylinder, a bidirectional hydraulic actuator which acts along the supporting direction of the foundation pit is embedded in the cylinder accommodating cavity of the fixed cylinder, a valve used for controlling the on-off state is arranged on an oil inlet pipeline of the bidirectional hydraulic actuator, and a prestressed oil pump is assembled on the bidirectional hydraulic actuator; the movable part of the movable head comprises a movable cylinder body sleeved on the periphery of the fixed cylinder body, and the movable cylinder body is provided with a movable head connecting flange; the spring energy storage tank comprises an energy storage tank body, an oil storage chamber for containing hydraulic oil is arranged in the energy storage tank body, an oil cylinder, a built-in oil pump, a large stroke spring and a hydraulic adjusting actuator are arranged in the energy storage tank body, the large stroke spring is positioned between a piston of the oil cylinder and the hydraulic adjusting actuator, the piston extending end of the oil cylinder at one end of the large stroke spring is connected, and the other end of the large stroke spring is connected with the driving end of the hydraulic adjusting actuator; an oil inlet of the built-in oil pump is communicated with the oil storage cavity through an oil pipeline, an oil outlet of the built-in oil pump is communicated with an oil cavity of the oil cylinder through the oil pipeline, an oil pressure output pipeline communicated with the oil cavity of the oil cylinder is further arranged on the tank body of the energy storage tank, and the oil pressure output pipeline is provided with a two-way oil valve; d. the adjustable joint is characterized in that inner support stay bars and adjustable movable joints are positioned and installed, two adjacent inner support stay bars are connected through a dry type connecting mechanism, and a section steel end flange of the inner support stay bar connected with the adjustable movable joint is connected with a movable joint connecting flange through a flange screw; an oil inlet pipeline of the bidirectional hydraulic actuator, an oil outlet pipeline of the prestressed oil pump and an oil pressure output pipeline of the spring energy storage tank are connected through a three-way oil pipe, a pressure sensor is arranged in the oil inlet pipeline of the bidirectional hydraulic actuator, and the pressure sensor, the prestressed oil pump and the built-in oil pump of the spring energy storage tank are respectively and electrically connected with an oil pressure controller; for the inner support stay bar with the core section steel being I-shaped section steel, the I-shaped section steel connected with the dry-type connecting mechanism is respectively provided with section steel screw holes which are sequentially arranged at intervals from front to back; the dry type connecting mechanism comprises a middle connecting web plate, the middle connecting web plate is provided with reinforcing ribs, and the middle connecting web plate is provided with web plate screw holes which are sequentially arranged at intervals from front to back; the front end part of the middle connecting web plate is connected with the I-shaped section steel of the inner support stay bar at the front side through screws, the rear end part of the middle connecting web plate is connected with the I-shaped section steel of the inner support stay bar at the rear side through screws, and the screws are inserted into web plate screw holes and section steel screw holes at corresponding positions; for the inner support stay bar with the core section steel being the circular section steel, at least two section steel ear plates which are uniformly distributed in the circumferential direction are welded on the outer circumferential surface of each circular section steel connected with the dry-type connecting mechanism respectively, each section steel ear plate is in a strip shape and extends along the front-back direction respectively, and each section steel ear plate is provided with ear plate screw holes which are sequentially arranged from front to back at intervals; the dry type connecting mechanism comprises intermediate connecting webs the number of which is consistent with that of the section steel ear plates of the circular section steel, each intermediate web comprises a web main body in an arc shape, web ear plates are arranged at two longitudinal edge parts of the web main body respectively, and each web ear plate is provided with web screw holes which are sequentially arranged at intervals along the front-back direction; the front end part of each intermediate connecting web plate extends into the space between two adjacent section steel ear plates of the inner support stay bar on the front side respectively, and the rear end part of each intermediate connecting web plate extends into the space between two adjacent section steel ear plates of the inner support stay bar on the rear side respectively; the front end part of each web plate ear plate is respectively connected with the section steel ear plate at the corresponding position of the inner support stay bar at the front side through screws, the rear end part of each web plate ear plate is respectively connected with the section steel ear plate at the corresponding position of the inner support stay bar at the rear side through screws, and each screw is respectively inserted into an ear plate screw hole and a web plate screw hole at the corresponding positions; e. the prestress oil pump is started through the oil pressure controller and drives the bidirectional hydraulic actuator to act so as to realize prestress loading on the inner support stay bar; f. after the prestress loading is finished, closing a valve of an oil inlet pipeline of the bidirectional hydraulic actuator, controlling a prestress oil pump to stop acting by an oil pressure controller, and controlling a built-in oil pump of the spring energy storage tank to start by the oil pressure controller so as to carry out oil pressure balance through the spring energy storage tank; when the oil pressure value acquired by the pressure sensor deviates from a preset value, the oil pressure controller controls the built-in oil pump to act and realize pressurization or pressure relief; g. and unloading the oil pressure after the foundation pit construction is finished, dismantling the components and clearing the site. Through the steps, the construction method has the advantages of simple construction and capability of adjusting the inner lining of the stay bar.

Drawings

The invention will be further described with reference to the drawings to which, however, the embodiments shown in the drawings do not constitute any limitation.

Fig. 1 is a schematic structural diagram of an inner support stay.

Fig. 2 is a schematic structural view of the stay bar assembly.

Fig. 3 is an exploded view of the brace assembly of fig. 2.

Fig. 4 is an exploded view of the brace assembly of fig. 2 in another position.

Fig. 5 is a schematic structural diagram of the adjustable swivel head.

Fig. 6 is a schematic structural diagram of another embodiment of the inner support strut.

Fig. 7 is a schematic structural view of another embodiment of a brace bar assembly.

Fig. 8 is an exploded view of the brace bar assembly of fig. 7.

Fig. 9 is a schematic structural diagram of the spring energy storage tank.

Fig. 10 is a schematic structural view of an FRP pipe.

Fig. 1 to 10 include:

1-brace rod component 11-inner support brace rod

111-core section steel 1111-steel end flange

1112-shaped steel screw hole 1113-shaped steel lug plate

1114-otic placode screw hole 112-concrete section

113 FRP pipe 1131 optical fiber sensor

12-Dry connecting mechanism 121-intermediate connecting web

1211 web screw hole 1212 reinforcing rib

1213 web body 1214 web lug

2-adjustable moving head 21-moving part of moving head

211-movable cylinder 212-movable head connecting flange

22-movable head fixing part 221-fixed tailstock

222-fixed cylinder 223-cylinder containing cavity

23-bidirectional hydraulic actuator 3-spring energy storage tank

31-energy storage tank body 32-oil cylinder

321-piston 33-internal oil pump

34-large stroke spring 35-adjusting hydraulic actuator

36-oil delivery pipe 37-oil pressure output pipe

38-two-way oil valve 39-auxiliary oil pump.

Detailed Description

The present invention will be described below with reference to specific embodiments.

As shown in fig. 1 to 9, a reusable foundation pit dry-type connection inner support system comprises a brace rod assembly 1, an adjustable swivel head 2 and a spring energy storage tank 3.

The support rod assembly 1 comprises inner support rods 11 which are sequentially arranged at intervals along the supporting direction of a foundation pit, each inner support rod 11 comprises a core section steel 111, a concrete part 112 which is poured and surrounds the periphery of the core section steel 111, and an FRP pipe 113 which is wrapped and sleeved on the periphery of the concrete part 112, the front end part of the core section steel 111 is protruded and extended to the front end side of the concrete part 112, and the rear end part of the core section steel 111 is protruded and extended to the rear end side of the concrete part 112; a dry connecting mechanism 12 is installed between two adjacent inner support struts 11, the front end of the dry connecting mechanism 12 is connected to the rear end of the core section steel 111 of the front inner support strut 11, and the rear end of the dry connecting mechanism 12 is connected to the front end of the core section steel 111 of the rear inner support strut 11.

Further, the adjustable moving head 2 is located at one end side of the stay bar assembly 1, the adjustable moving head 2 comprises a moving head moving part 21 and a moving head fixing part 22, the moving head fixing part 22 comprises a fixing tailstock 221 and a fixing cylinder 222 arranged on the fixing tailstock 221, a cylinder accommodating cavity 223 opened towards the stay bar assembly 1 side is formed in the fixing cylinder 222, and a bidirectional hydraulic actuator 23 moving along the foundation pit supporting direction is embedded in the cylinder accommodating cavity 223 of the fixing cylinder 222; the movable part 21 of the movable head comprises a movable cylinder 211 sleeved on the periphery of the fixed cylinder 222, and the end part of the movable cylinder 211 close to one side of the stay bar component 1 is provided with a movable head connecting flange 212; a section steel end flange 1111 is welded at the end part of the core section steel 111 of the inner support stay bar 11 close to the adjustable loose head 2, and the section steel end flange 1111 is connected with the loose head connecting flange 212 through flange screws.

Furthermore, the spring energy storage tank 3 comprises an energy storage tank body 31, an oil storage chamber for containing hydraulic oil is arranged inside the energy storage tank body 31, an oil cylinder 32, a built-in oil pump 33, a large stroke spring 34 and an adjusting hydraulic actuator 35 are arranged inside the energy storage tank body 31, the large stroke spring 34 is positioned between a piston 321 of the oil cylinder 32 and the adjusting hydraulic actuator 35, the extending end of the piston 321 of the oil cylinder 32 at one end of the large stroke spring 34 is connected, and the other end of the large stroke spring 34 is connected with the driving end of the adjusting hydraulic actuator 35; an oil inlet of the built-in oil pump 33 is communicated with the oil storage cavity through an oil pipeline 36, an oil outlet of the built-in oil pump 33 is communicated with an oil cavity of the oil cylinder 32 through the oil pipeline 36, the energy storage tank body 31 is further provided with an oil pressure output pipeline 37 communicated with the oil cavity of the oil cylinder 32, and the oil pressure output pipeline 37 is provided with a two-way oil valve 38; the built-in oil pump 33 is a high-pressure plunger pump. As shown in fig. 9, the adjusting hydraulic actuator 35 of the spring energy storage tank 3 is equipped with an auxiliary oil pump 39, the auxiliary oil pump 39 is connected with the adjusting hydraulic actuator 35 through an oil pipeline 36, and the auxiliary oil pump 39 is electrically connected with the oil pressure controller.

It should be noted that the two-way hydraulic actuator 23 of the adjustable moving head 2 is equipped with a prestressed oil pump, and an oil inlet pipeline of the two-way hydraulic actuator 23, an oil outlet pipeline of the prestressed oil pump and an oil pressure output pipeline 37 of the spring energy storage tank 3 are connected through a three-way oil pipe; the reusable foundation pit dry-type connection inner support system is provided with an oil pressure controller, an oil inlet pipeline of the bidirectional hydraulic actuator 23 is internally provided with a pressure sensor, and the pressure sensor, the prestressed oil pump and the built-in oil pump 33 of the spring energy storage tank 3 are respectively electrically connected with the oil pressure controller; the oil inlet pipeline of the bidirectional hydraulic actuator 23 is also provided with a valve for controlling the on-off state. Preferably, the oil pressure controller of the present invention is a PLC controller.

As shown in fig. 1 to 5, the core section steel 111 of the inner support stay 11 of the stay assembly 1 is an i-shaped section steel, and each i-shaped section steel connected with the dry-type connecting mechanism 12 is respectively provided with section steel screw holes 1112 arranged at intervals from front to back; the dry connecting mechanism 12 includes an intermediate connecting web 121, and the intermediate connecting web 121 is provided with web screw holes 1211 arranged at intervals from front to back; the front end of the intermediate connecting web 121 is connected to the i-shaped steel of the front inner support stay 11 by screws, the rear end of the intermediate connecting web 121 is connected to the i-shaped steel of the rear inner support stay 11 by screws, and the screws are inserted into the web screw holes 1211 and the section steel screw holes 1112 at corresponding positions. Preferably, the intermediate connecting web 121 is provided with a reinforcing rib 1212, and the reinforcing rib 1212 can improve the stability of the node steel plate and ensure the bearing capacity of the node area.

As shown in fig. 6 to 8, the core section steel 111 of the inner support stay 11 of the stay assembly 1 is a circular section steel, at least two section steel ear plates 1113 which are uniformly distributed on the circumference are welded on the outer circumferential surface of each circular section steel connected with the dry-type connecting mechanism 12, each section steel ear plate 1113 is in a strip shape, each section steel ear plate 1113 extends along the front-back direction, and each section steel ear plate 1113 is provided with ear plate screw holes 1114 which are sequentially arranged from front to back at intervals; the dry-type connecting mechanism 12 comprises intermediate connecting webs 121 the number of which is consistent with that of the section steel ear plates 1113 of the round section steel, each intermediate web comprises a web main body 1213 in an arc shape, two longitudinal edge parts of each web main body 1213 are provided with web ear plates 1214, and each web ear plate 1214 is provided with web screw holes 1211 which are sequentially arranged at intervals along the front-back direction; the front end part of each intermediate connecting web plate 121 extends into the space between two adjacent steel ear plates 1113 of the inner support stay 11 on the front side, and the rear end part of each intermediate connecting web plate 121 extends into the space between two adjacent steel ear plates 1113 of the inner support stay 11 on the rear side; the front end of each web lug 1214 is connected to the steel lug 1113 at the corresponding position of the front inner support stay 11 by screws, the rear end of each web lug 1214 is connected to the steel lug 1113 at the corresponding position of the rear inner support stay 11 by screws, and the screws are inserted into the lug screw holes 1114 and the web screw holes 1211 at the corresponding positions.

As a preferred embodiment, as shown in fig. 10, an optical fiber sensor 1131 is provided inside the tube wall of the FRP tube 113; preferably, the optical fiber sensor 1131 is a cross-spiral double-helix structure, and in order to reduce the manufacturing difficulty, the optical fiber sensor 1131 can be wound together with the fiber bundle in the manufacturing process of the FRP pipe 113, that is, the helix angle of the optical fiber sensor 1131 is the same as the fiber angle of the FRP pipe 113 material. The FRP pipe 113 can form an internal force and deformation monitoring system by adding an optical fiber sensor 1131, is used for monitoring the load stress level of the stay bar and the deformation of the stay bar, and plays roles in unloading and instability early warning; when the FRP pipe 113 is damaged and deformed, the optical fiber sensor 1131 is deformed, and the FRP pipe 113 is damaged and positioned by a positioning technology.

Compared with the traditional foundation pit inner supporting system, the reusable foundation pit dry-type connection inner supporting system has the following advantages:

1. the inner support stay bar 11 adopts FRP pipes 113 to restrain the combination of the concrete part 112 and the core section steel 111: the strength of the core section steel 111 is high, main bearing capacity can be provided, meanwhile, the core section steel 111 is protected by the concrete part 112 and the FRP pipe 113, so that the buckling bearing capacity can be effectively improved, the concrete part 112 and the FRP pipe 113 can isolate the core section steel 111 from air, and the core section steel 111 can be ensured not to be corroded; the concrete part 112 has high compressive strength, the bearing capacity of the stay bar can be effectively improved, the stress state of the concrete part 112 is three-axis compression in the operation of the stay bar, the brittleness of the three-axis compression concrete is obviously reduced, and the stability of the material property is kept on the basis of providing transverse support for the core section steel 111; the FRP pipe 113 is of a thin-wall structure, has large transverse deformation constraint capacity, can effectively constrain the concrete part 112, improves the working performance of the concrete part 112, further improves the buckling bearing capacity of the core section steel 111, and the inner concrete part 112 can improve the buckling bearing capacity of the FRP pipe 113 pipe wall and reduce the deformation of the FRP pipe 113 material; the three materials supplement each other, and the advantages of the three materials are fully exerted;

2. the FRP pipe 113 has high corrosion resistance, and can greatly prolong the service life of the stay bar while restraining the concrete part 112;

3. the FRP material is light, the thin-wall FRP pipe 113 material can be selected for the cross section design of the brace rod, and the self weight of the brace rod is reduced;

4. the FRP material is high in strength, and can effectively restrain the internal concrete part 112 and improve the compressive strength of the concrete part 112, so that the cross section bearing capacity of the support rod is improved;

5. the FRP pipe 113 is high in strength and is positioned on the surface of the stay bar, so that the section inertia moment of the stay bar can be effectively improved, and the stable bearing capacity of the stay bar is further improved;

6. the FRP pipe 113 can replace a part of section steel, so that the use amount of the section steel is reduced, the cost is reduced, and the self weight of the support rod can be reduced;

7. concrete is not poured in the core section steel 111, so that the support is effectively positioned on the edge of the cross section, the quality of the support rod is reduced, and the stability of the support rod is ensured;

8. a bidirectional hydraulic actuator 23 arranged in the adjustable moving head 2 is used as a loading and unloading power source;

9. the adjustable movable head 2 can be loaded, compensated, locked and unloaded after pressurization through hydraulic control;

10. and after the installation is finished, pressure monitoring and compensation are carried out through an oil pipe: when the hydraulic control system works, the pressure sensor acquires an oil pressure signal and feeds the oil pressure signal back to the oil pressure controller, the oil pressure controller can perform oil pressure early warning, and oil pressure adjustment is performed through authorization of professionals;

11. the large-stroke spring 34 can buffer oil pressure change so as to ensure stable oil pressure in the construction process;

12. the dry type connecting mechanism 12 can realize support length adjustment by changing the mounting position of the screw, and the stay bar is high in dismounting efficiency and good in length adaptability;

13. the spring energy storage tank 3 is used for buffering the oil pressure change of the adjustable moving head 2 so as to automatically adjust the supporting load of the side of the foundation pit;

14. the large-stroke spring 34 has adjustable rigidity, so that the stability of oil pressure redundancy can be ensured to a certain extent; the rigidity adjustment of the large-stroke spring 34 is adjusted through the adjusting hydraulic actuator 35, when the rigidity of the large-stroke spring 34 needs to be increased, the adjusting hydraulic actuator 35 extends out, and otherwise, the adjusting hydraulic actuator 35 contracts; the adjusting hydraulic actuator 35 used for adjusting the stiffness of the large-stroke spring 34 is loaded and unloaded by an auxiliary oil pump 39.

The construction method of the reusable foundation pit dry-type connection inner support system can be used for construction, and specifically comprises the following steps:

a. selecting the type of the inner support stay bar 11 according to the engineering support load condition, wherein the inner support stay bar 11 comprises a core section steel 111, a concrete part 112 cast and surrounding the periphery of the core section steel 111, and an FRP pipe 113 wrapping the periphery of the concrete part 112, the front end part of the core section steel 111 is protruded to extend to the front end side of the concrete part 112, and the rear end part of the core section steel 111 is protruded to extend to the rear end side of the concrete part 112; the core section steel 111 of the inner support stay bar 11 is I-shaped section steel or round section steel, and the end part of the core section steel 111 of the inner support stay bar 11 connected with the adjustable swivel head 2 is welded with a section steel end flange 1111;

b. selecting the length of the inner support stay bar 11 according to the size of the engineering foundation pit;

c. the inner support stay bar 11, the adjustable moving head 2, the spring energy storage tank 3 and the dry type connecting mechanism 12 are transported to a construction site;

the adjustable flexible head 2 comprises a flexible head moving part 21 and a flexible head fixing part 22, the flexible head fixing part 22 comprises a fixed tailstock 221 and a fixed cylinder 222 arranged on the fixed tailstock 221, a cylinder accommodating cavity 223 which is opened towards the side of the stay bar component 1 is formed in the fixed cylinder 222, a bidirectional hydraulic actuator 23 which acts along the supporting direction of the foundation pit is embedded in the cylinder accommodating cavity 223 of the fixed cylinder 222, a valve used for controlling the on-off state is arranged on an oil inlet pipeline of the bidirectional hydraulic actuator 23, and a prestressed oil pump is arranged on the bidirectional hydraulic actuator 23; the movable part 21 of the movable head comprises a movable cylinder 211 sleeved on the periphery of the fixed cylinder 222, and the movable cylinder 211 is provided with a movable head connecting flange 212;

the spring energy storage tank 3 comprises an energy storage tank body 31, an oil storage chamber for containing hydraulic oil is arranged inside the energy storage tank body 31, an oil cylinder 32, a built-in oil pump 33, a large stroke spring 34 and an adjusting hydraulic actuator 35 are arranged inside the energy storage tank body 31, the large stroke spring 34 is positioned between a piston 321 of the oil cylinder 32 and the adjusting hydraulic actuator 35, the extending end of the piston 321 of the oil cylinder 32 at one end of the large stroke spring 34 is connected, and the other end of the large stroke spring 34 is connected with the driving end of the adjusting hydraulic actuator 35; an oil inlet of the built-in oil pump 33 is communicated with the oil storage cavity through an oil pipeline 36, an oil outlet of the built-in oil pump 33 is communicated with an oil cavity of the oil cylinder 32 through the oil pipeline 36, the energy storage tank body 31 is further provided with an oil pressure output pipeline 37 communicated with the oil cavity of the oil cylinder 32, and the oil pressure output pipeline 37 is provided with a two-way oil valve 38;

d. the inner support stay bars 11 and the adjustable swivel heads 2 are positioned and installed, two adjacent inner support stay bars 11 are connected through a dry type connecting mechanism 12, and section steel end flanges 1111 of the inner support stay bars 11 connected with the adjustable swivel heads 2 are connected with a swivel head connecting flange 212 through flange screws;

the oil inlet pipeline of the bidirectional hydraulic actuator 23, the oil outlet pipeline of the prestressed oil pump and the oil pressure output pipeline 37 of the spring energy storage tank 3 are connected through a three-way oil pipe, a pressure sensor is arranged in the oil inlet pipeline of the bidirectional hydraulic actuator 23, and the pressure sensor, the prestressed oil pump and the built-in oil pump 33 of the spring energy storage tank 3 are respectively electrically connected with an oil pressure controller;

for the inner support stay bar 11 with the core section steel 111 being i-shaped section steel, the i-shaped section steel connected with the dry-type connecting mechanism 12 is respectively provided with section steel screw holes 1112 which are sequentially arranged from front to back at intervals; the dry connecting mechanism 12 comprises an intermediate connecting web 121, the intermediate connecting web 121 is provided with a reinforcing rib 1212, and the intermediate connecting web 121 is provided with web screw holes 1211 which are sequentially arranged from front to back at intervals; the front end of the intermediate connecting web 121 is connected to the i-shaped steel of the front inner support stay 11 by screws, the rear end of the intermediate connecting web 121 is connected to the i-shaped steel of the rear inner support stay 11 by screws, and the screws are inserted into the web screw holes 1211 and the section steel screw holes 1112 at corresponding positions;

for the inner support stay 11 with the core section steel 111 being circular section steel, at least two section steel ear plates 1113 which are uniformly distributed on the circumference are welded on the outer circumference surface of each circular section steel connected with the dry-type connecting mechanism 12, each section steel ear plate 1113 is in a strip shape, each section steel ear plate 1113 extends along the front-back direction, and each section steel ear plate 1113 is provided with ear plate screw holes 1114 which are sequentially arranged from front to back at intervals; the dry-type connecting mechanism 12 comprises intermediate connecting webs 121 the number of which is consistent with that of the section steel ear plates 1113 of the round section steel, each intermediate web comprises a web main body 1213 in an arc shape, two longitudinal edge parts of each web main body 1213 are provided with web ear plates 1214, and each web ear plate 1214 is provided with web screw holes 1211 which are sequentially arranged at intervals along the front-back direction; the front end part of each intermediate connecting web plate 121 extends into the space between two adjacent steel ear plates 1113 of the inner support stay 11 on the front side, and the rear end part of each intermediate connecting web plate 121 extends into the space between two adjacent steel ear plates 1113 of the inner support stay 11 on the rear side; the front end part of each web lug 1214 is respectively connected with the section steel lug 1113 at the corresponding position of the front inner support stay 11 through screws, the rear end part of each web lug 1214 is respectively connected with the section steel lug 1113 at the corresponding position of the rear inner support stay 11 through screws, and the screws are respectively inserted into the lug screw hole 1114 and the web screw hole 1211 at the corresponding positions;

e. the prestress oil pump is started through the oil pressure controller and drives the bidirectional hydraulic actuator 23 to act so as to realize prestress loading on the inner support stay bar 11;

f. after the prestress loading is finished, closing a valve of an oil inlet pipeline of the bidirectional hydraulic actuator 23, controlling the prestress oil pump to stop acting by the oil pressure controller, and controlling the built-in oil pump 33 of the spring energy storage tank 3 to start by the oil pressure controller so as to perform oil pressure balance through the spring energy storage tank 3; when the oil pressure value obtained by the pressure sensor deviates from a preset value, the oil pressure controller controls the built-in oil pump 33 to act and realize pressurization or pressure relief;

According to the above situation, through the structural design, the reusable foundation pit dry-type connection inner support system has the advantages of novel structural design, simple foundation pit inner support construction, recyclability, low inner support use loss and capability of realizing inner support adjustment of the support rod. In addition, the construction method of the reusable foundation pit dry-type connection inner support system has the advantages of simple construction and realization of inner and outer adjustment of the stay bar.

The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.

Claims

1. The utility model provides a repeatedly usable's foundation ditch dry-type connection inner support system which characterized in that: comprises a stay bar component (1), an adjustable flexible joint (2) and a spring energy storage tank (3);

the support rod assembly (1) comprises inner support rods (11) which are sequentially arranged at intervals along the supporting direction of a foundation pit, each inner support rod (11) comprises a core section steel (111), a concrete part (112) which is poured and surrounds the periphery of the core section steel (111), and an FRP pipe (113) which is wrapped on the periphery of the concrete part (112), the front end part of the core section steel (111) protrudes and extends to the front end side of the concrete part (112), and the rear end part of the core section steel (111) protrudes and extends to the rear end side of the concrete part (112); a dry type connecting mechanism (12) is arranged between two adjacent inner support stay bars (11), the front end part of the dry type connecting mechanism (12) is connected with the rear end part of the core section steel (111) of the inner support stay bar (11) at the front side, and the rear end part of the dry type connecting mechanism (12) is connected with the front end part of the core section steel (111) of the inner support stay bar (11) at the rear side;

the adjustable moving head (2) is located at one end side of the stay bar component (1), the adjustable moving head (2) comprises a moving head moving part (21) and a moving head fixing part (22), the moving head fixing part (22) comprises a fixing tailstock (221) and a fixing barrel (222) arranged on the fixing tailstock (221), a barrel accommodating cavity (223) which is opened towards the stay bar component (1) side is formed in the fixing barrel (222), and a bidirectional hydraulic actuator (23) which moves along the foundation pit supporting direction is embedded in the barrel accommodating cavity (223) of the fixing barrel (222); the movable part (21) of the movable joint comprises a movable cylinder (211) sleeved on the periphery of the fixed cylinder (222), and the end part of the movable cylinder (211) close to one side of the stay bar component (1) is provided with a movable joint connecting flange (212); a section steel end flange (1111) is welded at the end part of the core section steel (111) of the inner support stay bar (11) close to the adjustable loose head (2), and the section steel end flange (1111) is connected with a loose head connecting flange (212) through flange screws;

the spring energy storage tank (3) comprises an energy storage tank body (31), an oil storage chamber for containing hydraulic oil is arranged inside the energy storage tank body (31), an oil cylinder (32), a built-in oil pump (33), a large stroke spring (34) and an adjusting hydraulic actuator (35) are arranged inside the energy storage tank body (31), the large stroke spring (34) is located between a piston (321) of the oil cylinder (32) and the adjusting hydraulic actuator (35), the extending end of the piston (321) of the oil cylinder (32) at one end of the large stroke spring (34) is connected, and the other end of the large stroke spring (34) is connected with the driving end of the adjusting hydraulic actuator (35); an oil inlet of the built-in oil pump (33) is communicated with the oil storage chamber through an oil pipeline (36), an oil outlet of the built-in oil pump (33) is communicated with an oil cavity of the oil cylinder (32) through the oil pipeline (36), the energy storage tank body (31) is also provided with an oil pressure output pipeline (37) communicated with the oil cavity of the oil cylinder (32), and the oil pressure output pipeline (37) is provided with a two-way oil valve (38);

a two-way hydraulic actuator (23) of the adjustable moving head (2) is provided with a prestressed oil pump, and an oil inlet pipeline of the two-way hydraulic actuator (23), an oil outlet pipeline of the prestressed oil pump and an oil pressure output pipeline (37) of the spring energy storage tank (3) are connected through a three-way oil pipe; the reusable foundation pit dry-type connection inner support system is provided with an oil pressure controller, an oil inlet pipeline of the bidirectional hydraulic actuator (23) is internally provided with a pressure sensor, and the pressure sensor, the prestressed oil pump and the built-in oil pump (33) of the spring energy storage tank (3) are respectively and electrically connected with the oil pressure controller; the oil inlet pipeline of the bidirectional hydraulic actuator (23) is also provided with a valve for controlling the on-off state.

2. A reusable foundation pit dry-connect internal support system as claimed in claim 1, wherein: the core section steel (111) of the inner support stay bar (11) of the stay bar assembly (1) is I-shaped section steel, and each I-shaped section steel connected with the dry-type connecting mechanism (12) is provided with section steel screw holes (1112) which are sequentially arranged from front to back at intervals;

the dry type connecting mechanism (12) comprises a middle connecting web plate (121), and web plate screw holes (1211) which are sequentially arranged from front to back at intervals are formed in the middle connecting web plate (121); the front end part of the middle connecting web plate (121) is connected with the I-shaped steel of the inner support stay bar (11) at the front side through screws, the rear end part of the middle connecting web plate (121) is connected with the I-shaped steel of the inner support stay bar (11) at the rear side through screws, and the screws are inserted into web plate screw holes (1211) and section steel screw holes (1112) at corresponding positions.

3. A reusable foundation pit dry-connect internal support system as claimed in claim 2, wherein: the intermediate connecting web (121) is provided with reinforcing ribs (1212).

4. A reusable foundation pit dry-connect internal support system as claimed in claim 1, wherein: the core section steel (111) of the inner support stay bar (11) of the stay bar assembly (1) is circular section steel, at least two section steel ear plates (1113) which are uniformly distributed on the circumference are welded on the outer circumferential surface of each circular section steel connected with the dry-type connecting mechanism (12) respectively, each section steel ear plate (1113) is in a strip shape respectively, each section steel ear plate (1113) extends along the front-back direction respectively, and each section steel ear plate (1113) is provided with ear plate screw holes (1114) which are sequentially arranged from front to back at intervals;

the dry type connecting mechanism (12) comprises intermediate connecting webs (121) the number of which is consistent with that of the section steel ear plates (1113) of the round section steel, each intermediate web comprises a web main body (1213) in an arc shape, two longitudinal edge parts of each web main body (1213) are provided with web ear plates (1214), and each web ear plate (1214) is provided with web screw holes (1211) which are sequentially arranged at intervals along the front-back direction;

the front end part of each intermediate connecting web plate (121) extends into the space between two adjacent steel ear plates (1113) of the inner support stay bar (11) at the front side respectively, and the rear end part of each intermediate connecting web plate (121) extends into the space between two adjacent steel ear plates (1113) of the inner support stay bar (11) at the rear side respectively; the front end part of each web lug plate (1214) is respectively connected with the section steel lug plate (1113) at the corresponding position of the front inner support stay bar (11) through screws, the rear end part of each web lug plate (1214) is respectively connected with the section steel lug plate (1113) at the corresponding position of the rear inner support stay bar (11) through screws, and the screws are respectively inserted into the lug plate screw hole (1114) and the web plate screw hole (1211) at the corresponding positions.

5. A reusable foundation pit dry-connect internal support system as claimed in claim 1, wherein: and an optical fiber sensor (1131) is arranged inside the tube wall of the FRP tube (113).

6. A reusable foundation pit dry-connect internal support system as claimed in claim 5, wherein: the optical fiber sensor (1131) is of a crossed spiral double-helix structure, and the helix angle of the optical fiber sensor (1131) is the same as the fiber angle of the FRP pipe (113).

7. A reusable foundation pit dry-connect internal support system as claimed in claim 1, wherein: the adjusting hydraulic actuator (35) of the spring energy storage tank (3) is provided with an auxiliary oil pump (39), the auxiliary oil pump (39) is connected with the adjusting hydraulic actuator (35) through an oil conveying pipeline (36), and the auxiliary oil pump (39) is electrically connected with the oil pressure controller.

8. A construction method for a reusable foundation pit dry-type connection inner support system is characterized by comprising the following steps:

a. selecting the type of the inner support stay bar (11) according to the engineering support load condition, wherein the inner support stay bar (11) comprises a core section steel (111), a concrete part (112) poured and surrounding the periphery of the core section steel (111), and an FRP pipe (113) wrapped on the periphery of the concrete part (112), the front end part of the core section steel (111) is protruded and extended to the front end side of the concrete part (112), and the rear end part of the core section steel (111) is protruded and extended to the rear end side of the concrete part (112); the core section steel (111) of the inner support stay bar (11) is I-shaped section steel or round section steel, and a section steel end flange (1111) is welded at the end part of the core section steel (111) of the inner support stay bar (11) connected with the adjustable swivel joint (2);

b. selecting the length of the inner supporting strut (11) according to the size of the engineering foundation pit;

c. the inner support stay bar (11), the adjustable flexible head (2), the spring energy storage tank (3) and the dry type connecting mechanism (12) are transported to a construction site;

the adjustable moving head (2) comprises a moving head moving part (21) and a moving head fixing part (22), the moving head fixing part (22) comprises a fixed tailstock (221) and a fixed cylinder (222) arranged on the fixed tailstock (221), a cylinder accommodating cavity (223) which is opened towards the side of the stay bar component (1) is formed in the fixed cylinder (222), a bidirectional hydraulic actuator (23) which acts along the supporting direction of a foundation pit is embedded in the cylinder accommodating cavity (223) of the fixed cylinder (222), a valve used for controlling the on-off state is arranged on an oil inlet pipeline of the bidirectional hydraulic actuator (23), and a prestress oil pump is assembled on the bidirectional hydraulic actuator (23); the movable part (21) of the movable joint comprises a movable cylinder body (211) sleeved on the periphery of the fixed cylinder body (222), and the movable cylinder body (211) is provided with a movable joint connecting flange (212);

d. the adjustable swivel joint is characterized in that the inner support stay bars (11) and the adjustable swivel joint (2) are positioned and installed, two adjacent inner support stay bars (11) are connected through a dry type connecting mechanism (12), and a section steel end flange (1111) of the inner support stay bar (11) connected with the adjustable swivel joint (2) is connected with a swivel joint connecting flange (212) through a flange screw;

an oil inlet pipeline of the bidirectional hydraulic actuator (23), an oil outlet pipeline of the prestressed oil pump and an oil pressure output pipeline (37) of the spring energy storage tank (3) are connected through a three-way oil pipe, a pressure sensor is arranged in the oil inlet pipeline of the bidirectional hydraulic actuator (23), and the pressure sensor, the prestressed oil pump and the built-in oil pump (33) of the spring energy storage tank (3) are respectively electrically connected with an oil pressure controller;

for the inner support stay bar (11) with the core section steel (111) being I-shaped section steel, section steel screw holes (1112) which are sequentially arranged from front to back at intervals are respectively formed in each I-shaped section steel connected with the dry-type connecting mechanism (12); the dry type connecting mechanism (12) comprises a middle connecting web plate (121), the middle connecting web plate (121) is provided with reinforcing ribs (1212), and the middle connecting web plate (121) is provided with web plate screw holes (1211) which are sequentially arranged from front to back at intervals; the front end part of the middle connecting web plate (121) is connected with the I-shaped steel of the inner support stay bar (11) at the front side through screws, the rear end part of the middle connecting web plate (121) is connected with the I-shaped steel of the inner support stay bar (11) at the rear side through screws, and the screws are inserted into web plate screw holes (1211) and section steel screw holes (1112) at corresponding positions;

for the inner support stay bar (11) with the core section steel (111) being circular section steel, the outer circumferential surface of each circular section steel connected with the dry-type connecting mechanism (12) is respectively welded with at least two section steel ear plates (1113) which are uniformly distributed on the circumference, each section steel ear plate (1113) is respectively in a strip shape, each section steel ear plate (1113) extends along the front-back direction, and each section steel ear plate (1113) is respectively provided with ear plate screw holes (1114) which are sequentially arranged at intervals from front to back; the dry type connecting mechanism (12) comprises intermediate connecting webs (121) the number of which is consistent with that of the section steel ear plates (1113) of the round section steel, each intermediate web comprises a web main body (1213) in an arc shape, two longitudinal edge parts of each web main body (1213) are provided with web ear plates (1214), and each web ear plate (1214) is provided with web screw holes (1211) which are sequentially arranged at intervals along the front-back direction; the front end part of each intermediate connecting web plate (121) extends into the space between two adjacent steel ear plates (1113) of the inner support stay bar (11) at the front side respectively, and the rear end part of each intermediate connecting web plate (121) extends into the space between two adjacent steel ear plates (1113) of the inner support stay bar (11) at the rear side respectively; the front end part of each web lug plate (1214) is respectively connected with the section steel lug plate (1113) at the corresponding position of the front inner support stay bar (11) through screws, the rear end part of each web lug plate (1214) is respectively connected with the section steel lug plate (1113) at the corresponding position of the rear inner support stay bar (11) through screws, and the screws are respectively inserted into the lug plate screw hole (1114) and the web plate screw hole (1211) at the corresponding positions;

e. the prestress oil pump is started through the oil pressure controller and drives the bidirectional hydraulic actuator (23) to act so as to realize prestress loading on the inner support stay bar (11);

f. after the prestress loading is finished, closing a valve of an oil inlet pipeline of the bidirectional hydraulic actuator (23), controlling a prestress oil pump to stop acting by the oil pressure controller, and controlling a built-in oil pump (33) of the spring energy storage tank (3) to start by the oil pressure controller so as to carry out oil pressure balance through the spring energy storage tank (3); when the oil pressure value obtained by the pressure sensor deviates from a preset value, the oil pressure controller controls the built-in oil pump (33) to act and realize pressurization or pressure relief action;

9. The construction method of the reusable foundation pit dry-type connection inner support system according to claim 8, wherein the construction method comprises the following steps: the fiber optic sensor (1131) is arranged inside the tube wall of the FRP tube (113), the fiber optic sensor (1131) is of a crossed spiral double-helix structure, and the helix angle of the fiber optic sensor (1131) is the same as the fiber angle of the FRP tube (113).

10. The construction method of the reusable foundation pit dry-type connection inner support system according to claim 8, wherein the construction method comprises the following steps: the adjusting hydraulic actuator (35) of the spring energy storage tank (3) is provided with an auxiliary oil pump (39), the auxiliary oil pump (39) is connected with the adjusting hydraulic actuator (35) through an oil conveying pipeline (36), and the auxiliary oil pump (39) is electrically connected with the oil pressure controller.