Bridge abutment foundation pit supporting structure suitable for space limitation

Abstract

The utility model discloses a bridge abutment foundation pit supporting structure suitable for space limitation, and relates to the technical field of bridge engineering. The bridge abutment foundation pit supporting structure comprises a soil cofferdam and a supporting assembly. The supporting assembly comprises two protective belt sets, a plurality of connecting assemblies and a supporting assembly. The protective belt group is formed by connecting a plurality of Larsen type steel sheet piles; wherein one protective belt group is arranged close to the soil cofferdam, and the other protective belt group is arranged close to the residential building; the connecting assemblies are symmetrically arranged on the protective belt sets on the two sides, each connecting assembly comprises an enclosing purlin and a plurality of purlin supports, the purlin supports are evenly distributed in the longitudinal direction of the protective belt sets and connected with the adjacent Larsen type steel sheet piles, and the enclosing purlins are connected with the top faces of the purlin supports and extend in the longitudinal direction of the protective belt sets. The supporting assemblies are arranged in the transverse direction of the protective belt set, and the two ends of each supporting assembly are connected with the surrounding purlins on the two sides respectively. The abutment foundation pit supporting structure can be suitable for abutment foundation pit supporting with limited space.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge engineering, and particularly relates to a bridge abutment foundation pit supporting structure suitable for space limitation. BACKGROUND

[0002] In the process of bridge engineering construction, the bridge abutment foundation pit supporting work is very important, and its effect is directly related to the construction safety and engineering quality. At present, the types of conventional bridge abutment foundation pit supporting structures are various, such as the cantilever foundation pit supporting structure of pile row-anchor rod structure, pile row-supporting structure and the like. The design theory of these traditional supporting structures is relatively mature, the construction technology is relatively stable, and rich practical experience has been accumulated under general site conditions, which can better meet the supporting needs of ordinary bridge abutment foundation pits.

[0003] However, in the actual engineering scene, when the engineering is in the city dense area, the narrow site area, or the environment with complex pipelines laid in the soil body, the traditional bridge abutment foundation pit supporting structure will have many problems. For example, the volume of the traditional bridge abutment foundation pit supporting structure is generally large, and it cannot be normally installed and used in the narrow space. Due to the fact that the bridge abutment is adjacent to the air and there are underground pipelines in the soil body, the traditional bridge abutment foundation pit supporting structure is easy to damage the underground pipelines during construction. CONTENT OF THE INVENTION

[0004] The main purpose of the present application is to provide a bridge abutment foundation pit supporting structure suitable for space limitation, which aims to solve the technical problem that the existing bridge abutment foundation pit supporting structure is difficult to support the bridge abutment foundation pit under space limitation.

[0005] To achieve the above-mentioned purpose, the present application provides a bridge abutment foundation pit supporting structure suitable for space limitation, which comprises a soil cofferdam and a supporting assembly, the soil cofferdam is provided with a foundation groove for installing the supporting assembly, and the supporting assembly comprises two protective belt groups, a plurality of connecting assemblies and supporting assemblies.

[0006] The protective belt group is connected by a plurality of Larsen steel sheet piles; one of the protective belt groups is arranged close to the soil cofferdam, and the other protective belt group is arranged close to the residential building;

[0007] A plurality of connecting assemblies are symmetrically arranged on the two protective belt groups, the connecting assembly comprises a surrounding purlin and a plurality of purlin supports, the purlin supports are uniformly distributed along the longitudinal direction of the protective belt group and connected with the adjacent Larsen steel sheet piles, and the surrounding purlin is connected with the top surface of the purlin support and arranged along the longitudinal direction of the protective belt group.

[0008] Each supporting assembly is arranged along the transverse direction of the protective belt group, and the two ends of each supporting assembly are connected with the surrounding purlins on both sides.

[0009] Optionally, the connecting assembly comprises a mounting workpiece, the mounting workpiece comprises a mounting plate and an adjustable component, one end of the mounting plate is provided with a first hook part, the mounting plate is hung on the Larsen steel sheet pile through the first hook part, the adjustable component is arranged on the side of the mounting plate away from the Larsen steel sheet pile, and the purlin support is connected with the mounting plate through the adjustable component and can be adjusted in height along the length direction of the mounting plate.

[0010] Optionally, the adjustable component comprises two oppositely arranged L-shaped members, the two L-shaped members are arranged in extension along the length direction of the mounting plate, and the two L-shaped members and the mounting plate form a T-shaped sliding groove, the connecting assembly further comprises a sliding block matched with the sliding groove, the sliding block is connected with the purlin support, and the sliding block and the L-shaped members are connected through a positioning member.

[0011] Optionally, the L-shaped member is provided with a plurality of first positioning holes in the length direction, the sliding block is provided with a plurality of second positioning holes matched with the first positioning holes, and the positioning member sequentially penetrates through the first positioning holes and the second positioning holes to connect the sliding block with the L-shaped member.

[0012] Optionally, the purlin support comprises a transverse bearing plate, a vertical connecting plate and an inclined stiffening plate, the vertical connecting plate is connected perpendicularly to one side of the transverse bearing plate, and the inclined stiffening plate is connected perpendicularly to the bottom surface of the transverse bearing plate; the transverse bearing plate, the vertical connecting plate and the L-shaped member form a clamping groove matched with the surrounding purlin.

[0013] Optionally, the supporting assembly comprises a steel support and two second hook parts, the two second hook parts are connected to the two ends of the steel support respectively, and each second hook part is hung on the adjacent surrounding purlin.

[0014] Optionally, the earth cofferdam is backfilled with cohesive soil, and the compaction degree of the backfill is greater than or equal to 85%.

[0015] Optionally, the earth cofferdam is provided with a seepage-proof composite geomembrane on one side.

[0016] Optionally, the steel sheet pile, the surrounding purlin and the purlin support are made of Q235 material.

[0017] Optionally, the steel support is a Q235 steel pipe with a diameter of 609 mm and a wall thickness of 12 mm.

[0018] The application can achieve the following beneficial effects:

[0019] The bridge abutment foundation pit supporting structure suitable for space limitation provided by the embodiment of the application adopts a soil cofferdam as a counter pressure body, uses the weight and friction of the soil body of the soil cofferdam to provide stable counterforce support for the open side foundation pit supporting, and further constructs an unbalanced thrust foundation pit supporting structure on the opposite side, which can efficiently resist the pressure applied by the soil body on the open side of the foundation pit and greatly enhances the stability of the foundation pit. Meanwhile, the structure adopts a protection belt group connected by Larsen steel sheet piles, compared with the traditional structure, the space occupied by the structure is smaller, and the driving position and mode of the Larsen steel sheet piles are relatively fixed, which has less influence on underground pipelines. The installation process of the connecting assembly and the supporting assembly does not involve large-scale operation near the underground pipelines, thereby effectively reducing the risk of damaging the underground pipelines, protecting the normal operation of urban infrastructure, reducing the maintenance cost and influence on the surrounding residents' life caused by pipeline damage. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram of the existing bridge abutment surrounding situation;

[0021] Figure 2 is a schematic diagram of the installation of a bridge abutment foundation pit supporting structure suitable for space limitation according to the embodiment of the application;

[0022] Figure 3 is a schematic diagram of the process of bridge abutment construction using the bridge abutment foundation pit supporting structure according to the embodiment of the application Figure 1 ;

[0023] Figure 4 is a schematic diagram of the process of bridge abutment construction using the bridge abutment foundation pit supporting structure according to the embodiment of the application Figure 2 ;

[0024] Figure 5 is a schematic diagram of the process of bridge abutment construction using the bridge abutment foundation pit supporting structure according to the embodiment of the application Figure 3 ;

[0025] Figure 6 is a schematic diagram of the process of bridge abutment construction using the bridge abutment foundation pit supporting structure according to the embodiment of the application Figure 4 ;

[0026] Figure 7 is a schematic diagram of the process of bridge abutment construction using the bridge abutment foundation pit supporting structure according to the embodiment of the application Figure 5 ;

[0027] Figure 8 is a schematic diagram of the supporting assembly of a bridge abutment foundation pit supporting structure suitable for space limitation according to the embodiment of the application;

[0028] Figure 9 is a schematic diagram of the installation of a mounting workpiece and a purlin support of a bridge abutment foundation pit supporting structure suitable for space limitation according to the embodiment of the application;

[0029] Figure 10 A top view schematic view of a mounting workpiece suitable for a bridge abutment foundation pit supporting structure with limited space according to an embodiment of the present application;

[0030] Figure 11 A structural schematic view of a purlin support suitable for a bridge abutment foundation pit supporting structure with limited space according to an embodiment of the present application.

[0031] In the drawings, reference numerals:

[0032] 1-residential building; 2-retaining wall; 3-earthen cofferdam; 4-foundation trench; 5-supporting assembly; 6-protection belt group; 7-connecting assembly; 8-supporting assembly; 9-enclosing purlin; 10-purlin support; 11-mounting workpiece; 12-mounting plate; 13-adjustable part; 14-first hook part; 15-L-shaped member; 16-sliding groove; 17-sliding block; 18-positioning part; 19-first positioning hole; 20-second positioning hole; 21-transverse bearing plate; 22-vertical connecting plate; 23-oblique stiffener; 24-clamping groove; 25-steel support; 26-second hook part; 27-anti-seepage composite geomembrane; 28-bear; 29-bridge abutment pile foundation.

[0033] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments in combination with the drawings. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be apparently and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0035] In order to solve the technical problem that the existing foundation pit supporting structure is difficult to meet the requirements of bridge abutment foundation pit supporting in the case of limited space, the present application proposes a new bridge abutment foundation pit supporting structure.

[0036] Referring to Figures 1 to 8 A bridge abutment foundation pit supporting structure suitable for limited space, the bridge abutment foundation pit supporting structure comprising an earthen cofferdam 3 and a supporting assembly 5, the earthen cofferdam 3 being provided with a foundation trench 4 for mounting the supporting assembly 5, the supporting assembly 5 comprising two protection belt groups 6, a plurality of connecting assemblies 7 and a supporting assembly 8;

[0037] The protection belt group 6 is connected by a plurality of Larsen steel sheet piles; one of the protection belt groups 6 is arranged close to the earthen cofferdam 3, and the other protection belt group 6 is arranged close to the residential building 1;

[0038] A plurality of connecting assemblies 7 are symmetrically arranged on the two sides of the protection belt group 6, and the connecting assembly 7 comprises a surrounding purlin 9 and a plurality of purlin supports 10, each purlin support 10 is uniformly distributed along the longitudinal direction of the protection belt group 6 and connected with the adjacent Larsen steel sheet pile, and the surrounding purlin 9 is connected with the top surface of the purlin support 10 and arranged along the longitudinal direction of the protection belt group 6.

[0039] Each support assembly 8 is arranged along the transverse direction of the protection belt group 6, and the two ends of each support assembly 8 are respectively connected with the surrounding purlins 9 on the two sides.

[0040] Specifically, the process of using the bridge abutment foundation pit support structure to construct the bridge abutment is as follows:

[0041] Before construction, the length and type of the Larsen steel sheet pile, the size of the support assembly 8, and the filling material and size of the soil cofferdam 3 required for construction are determined according to the design requirements of the bridge abutment foundation pit and the on-site geological exploration data. Pile driving equipment, welding equipment, measuring instruments and other construction tools and materials are prepared.

[0042] During construction, the soil cofferdam 3 is constructed and filled according to the design slope ratio and the top surface elevation on the open side. The soil cofferdam 3 can be constructed and filled in layers to ensure the density and stability of the soil cofferdam 3. After the construction of the soil cofferdam 3 is completed, the construction of the bridge abutment pile foundation 29 is carried out according to the position and size determined by the design.

[0043] After the construction of the bridge abutment pile foundation 29 is completed, the inner contour of the enclosure structure is determined according to the outer edge line of the main foundation pit structure and the width of the foundation pit trench. Using pile driving equipment, the Larsen steel sheet pile is driven into the river side according to the designed spacing, so that the Larsen steel sheet piles are mutually engaged. Then, the Larsen steel sheet pile is driven into the non-river side in the same way. During the construction process, the perpendicularity and the depth of the Larsen steel sheet pile into the soil must meet the design requirements.

[0044] After the Larsen steel sheet pile is driven and set, the existing retaining wall 2 in the river is removed, and then the foundation pit is excavated to the design elevation of the pit bottom in the form of a basin-type excavation foundation pit along the contour of the Larsen steel sheet pile, thereby forming the foundation trench 4. The purlin supports 10 are installed on the outer side wall of the Larsen steel sheet pile in sequence, and then the surrounding purlin 9 is installed on the top surface of the purlin support 10, and the support assemblies 8 are installed in sequence.

[0045] After the above steps are completed, the construction of the bridge pile cap 28 is carried out. When the strength of the pile cap 28 reaches the design strength, the trench between the pile cap 28 and the Larsen steel sheet pile is filled with C20 plain concrete, so that the filling elevation is flush with the top surface of the pile cap 28. Subsequently, the support assemblies 8 close to the pile cap 28 are removed in sequence, and the construction of the bridge abutment structure above the pile cap 28 is carried out in sequence. After the entire bridge abutment structure is constructed, the support assembly 8 located at the top of the foundation trench 4 is removed, and the abutment back is backfilled with sand and gravel. Finally, the Larsen steel sheet pile is pulled out, the soil cofferdam 3 is excavated, and the existing river is restored.

[0046] The bridge abutment foundation pit supporting structure proposed in the above embodiment uses the earth cofferdam 3 as a counterpressure body, uses the weight and friction of the earth body of the earth cofferdam 3 to provide stable counterforce support for the open side foundation pit supporting, further constructs an imbalance thrust foundation pit supporting structure on the opposite side, can efficiently resist the pressure exerted by the earth body on the open side of the foundation pit, and greatly enhances the stability of the foundation pit. At the same time, the structure uses the protection belt group 6 connected by the Larsen steel sheet piles, compared with the traditional structure, it occupies less space, and the driving position and mode of the Larsen steel sheet piles are relatively fixed, and the influence on underground pipelines is smaller. The installation process of the connecting assembly 7 and the supporting assembly 8 also does not involve large-scale operation near the underground pipelines, thereby effectively reducing the risk of damaging the underground pipelines, protecting the normal operation of the urban infrastructure, and reducing the maintenance cost and influence on the surrounding residents' life caused by pipeline damage.

[0047] As an implementable manner, referring to Figure 8 and Figure 9 , the connecting assembly 7 includes a mounting workpiece 11, the mounting workpiece 11 includes a mounting plate 12 and an adjustable component 13, one end of the mounting plate 12 is provided with a first hook portion 14, the mounting plate 12 is hung on the Larsen steel sheet pile through the first hook portion 14, the adjustable component 13 is arranged on the side of the mounting plate 12 away from the Larsen steel sheet pile, and the purlin support 10 is connected with the mounting plate 12 through the adjustable component 13 and can be adjusted in height along the length direction of the mounting plate 12.

[0048] Specifically, the purlin support 10 can be adjusted in height along the length direction of the mounting plate 12, so that the connecting assembly 7 can better adapt to complex geological conditions and different foundation pit supporting requirements. When encountering special geological conditions such as soft soil foundation, the surrounding earth body of the foundation pit may be unevenly settled, causing the relative position of the Larsen steel sheet pile to change. The adjustability of the height of the purlin support 10 can compensate for the influence caused by such changes in time, ensure the flatness and stability of the installation of the surrounding purlin 9, and ensure that the integrity and stability of the supporting structure are not affected. In addition, in different depth foundation pit engineering, the height of the surrounding purlin 9 is flexibly adjusted according to the design requirements, which can optimize the stress distribution of the supporting structure, effectively improve the resistance of the supporting structure to the earth pressure, and further protect the safety of the foundation pit construction.

[0049] As an implementable manner, referring to Figure 9 and Figure 10 , the adjustable component 13 includes two oppositely arranged L-shaped members 15L, the two L-shaped members 15L are arranged in extension along the length direction of the mounting plate 12, and the two L-shaped members 15L and the mounting plate 12 form a T-shaped sliding groove 16, the connecting assembly 7 further includes a sliding block 17 matched with the sliding groove 16, the sliding block 17 is connected with the purlin support 10, and the sliding block 17 and the L-shaped member 15L are connected through a positioning piece 18.

[0050] Specifically, the L-shaped member 15L and the mounting plate 12 form a T-shaped sliding groove 16, which is matched with the sliding block 17 and the positioning member 18, thereby optimizing the connection effect of the purlin support 10 and the mounting plate 12. The T-shaped sliding groove 16 provides stable guidance for the sliding block 17, so that the purlin support 10 can always remain stable during adjustment, avoiding shaking or deviation and ensuring the stability of the connection. At the same time, this structure makes the height adjustment of the purlin support 10 very simple. Only by loosening the positioning member 18 and sliding the sliding block 17 can the height of the purlin support 10 be easily adjusted. After adjustment, the positioning member 18 is installed and fixed. The whole process is fast and efficient, which can significantly improve the construction efficiency.

[0051] As an implementable manner, referring to Figure 9 , the L-shaped member 15L is provided with a plurality of first positioning holes 19 along the length direction, and the sliding block 17 is provided with a plurality of second positioning holes 20 matched with the first positioning holes 19. The positioning member 18 is sequentially inserted into the first positioning holes 19 and the second positioning holes 20 to connect the sliding block 17 and the L-shaped member 15L.

[0052] Specifically, the L-shaped member 15L is provided with a plurality of first positioning holes 19, and the sliding block 17 is provided with a plurality of second positioning holes 20 matched with the first positioning holes 19. The design of connecting the sliding block 17 and the L-shaped member 15L through the positioning member 18 not only ensures the stability of the bridge abutment foundation pit support structure, but also greatly improves the construction convenience. On the one hand, a large number of positioning holes provide rich choices for the height adjustment of the purlin support 10. Construction personnel can accurately fix the sliding block 17 and the L-shaped member 15L at the most suitable position according to the actual situation on site. On the other hand, this positioning method is simple to operate. Construction personnel only need to sequentially insert the positioning member 18 into the corresponding positioning holes to quickly complete the connection and fixation, which not only improves the construction efficiency, but also reduces the construction difficulty. Even in complex construction environment, the flexible adjustment of the height of the purlin support 10 can be easily realized, which meets different construction requirements.

[0053] As an implementable manner, referring to Figure 11 , the purlin support 10 comprises a horizontal bearing plate 21, a vertical connecting plate 22 and an inclined stiffening plate 23. The vertical connecting plate 22 is connected to one side of the horizontal bearing plate 21, and the inclined stiffening plate 23 is connected to the bottom surface of the horizontal bearing plate 21. The horizontal bearing plate 21, the vertical connecting plate 22 and the L-shaped member 15L form a clamping groove 24 matched with the surrounding purlin 9.

[0054] Specifically, the transverse bearing plate 21, the vertical connecting plate 22, and the L-shaped component 15L form a groove 24 that matches the waler 9, allowing the waler 9 to be directly inserted into it. This simplifies and speeds up installation, eliminating the need for complex positioning and fixing operations and significantly improving construction efficiency. Simultaneously, the groove 24 fits tightly against the waler 9, effectively limiting its displacement and enhancing its stability during use. The diagonal stiffening plate 23 is vertically connected to the bottom surface of the transverse bearing plate 21, strengthening the overall structural strength of the waler support 10. This ensures that the waler 9 remains stably fixed even under pressure from it, guaranteeing the reliability of the bridge abutment foundation pit support structure.

[0055] As an feasible approach, refer to Figure 8 The support assembly 8 includes a steel support 25 and two second hooks 26. The two second hooks 26 are respectively connected to the two ends of the steel support 25, and each second hook 26 is respectively hooked onto the adjacent waler 9.

[0056] Specifically, the steel support 25 possesses excellent strength and rigidity, providing reliable lateral support for the protective belts 6 on both sides, effectively resisting soil pressure and maintaining the overall stability of the foundation pit. The connection method between the second hook 26 and the waler 9 ensures a tight connection between the support component 8 and the waler 9, allowing for even distribution of support force, avoiding stress concentration, and further enhancing the safety and reliability of the support structure. Furthermore, this detachable connection method facilitates the installation, removal, and reuse of the support component 8, reducing construction costs.

[0057] As a feasible approach, the earth cofferdam 3 is backfilled with cohesive soil, with a backfill compaction degree greater than or equal to 85%.

[0058] Specifically, cohesive soil has excellent impermeability, effectively preventing the infiltration of groundwater and surface water, reducing water accumulation in the foundation pit, creating a dry working environment for foundation pit construction, and ensuring the smooth progress of construction. A compaction degree greater than or equal to 85% ensures that the soil cofferdam 3 has sufficient strength and stability to withstand the soil pressure on the free side of the foundation pit, providing reliable reaction support for the support structure, preventing collapse, slippage, and other accidents of the foundation pit sidewalls, and ensuring construction safety.

[0059] Optionally, the soil cofferdam 3 on the water-facing side shall be filled with woven bags and stacked according to the designed slope ratio. The woven bags shall be made of 200g / m anti-aging polypropylene woven fabric and the longitudinal and transverse tensile strength shall be ≥1750N / 5cm. The splicing and sewing of the woven bags shall be done by overlock sewing, and nylon thread shall be used for sewing. The strength of the sewing joint shall not be less than 70% of the original strength of the fabric. The water-facing side shall be sloped at a ratio of 1:1.5.

[0060] As a feasible approach, an impermeable composite geomembrane 27 is laid on one side of the earthen cofferdam 3.

[0061] Specifically, the impermeable composite geomembrane 27 has extremely low water permeability, which can effectively prevent the penetration of underground water and surface water, reduce the problems of soil softening and strength reduction inside the earth-cofferdam 3 caused by water leakage, and ensure that the earth-cofferdam 3 always maintains stable structural performance.

[0062] Optionally, the impermeable composite geomembrane 27 has a specification of 300g / 0.75mm PE / 300g, and a permeability coefficient of not more than 1x10-9cm / s.

[0063] As an implementable manner, the steel sheet pile, the surrounding purlin 9 and the purlin support 10 are made of Q235 material.

[0064] Specifically, the Q235 material has good comprehensive mechanical properties, moderate yield strength, can withstand the large pressure and stress generated during the foundation pit support process, effectively resist the lateral pressure of the soil, ensure the stability and reliability of the abutment foundation pit support structure, and ensure construction safety. In addition, it has good plasticity and toughness, and can produce certain deformation without brittle fracture when subjected to external force, can adapt to the uneven settlement and deformation of the soil around the foundation pit, and reduce the risk of structural damage.

[0065] As an implementable manner, the steel support 25 is made of Q235 steel pipe with a diameter of φ609mm and a wall thickness of 12mm.

[0066] Specifically, the large pipe diameter of φ609mm and the wall thickness of 12mm give the steel support 25 sufficient cross-sectional area and bending modulus, so that it can withstand large axial pressure and lateral load. In the foundation pit support, it can effectively resist the lateral pressure of the soil on the support structure, ensure the stability of the foundation pit, reduce the risk of foundation pit deformation and collapse, and ensure construction safety.

[0067] The above is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation using the contents of the specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A bridge abutment foundation pit support structure suitable for space restriction, characterized by, The bridge abutment foundation pit support structure comprises a soil cofferdam and a support assembly, the soil cofferdam is provided with a foundation groove for mounting the support assembly, and the support assembly comprises two protective belt groups, a plurality of connecting assemblies and support assemblies; The protective belt groups are connected by a plurality of Larsen steel sheet piles; one of the protective belt groups is arranged close to the soil cofferdam, and the other protective belt group is arranged close to a residential building; The connecting assemblies are symmetrically arranged on the protective belt groups on both sides, the connecting assembly comprises a surrounding purlin and a plurality of purlin supports, the purlin supports are uniformly distributed along the longitudinal direction of the protective belt group and connected with the adjacent Larsen steel sheet piles, the surrounding purlin is connected with the top surface of the purlin support and extends along the longitudinal direction of the protective belt group; Each support assembly is arranged along the transverse direction of the protective belt group, and the two ends of each support assembly are connected with the surrounding purlins on both sides.

2. The bridge abutment foundation pit support structure suitable for space restriction according to claim 1, characterized in that, The connecting assembly further comprises a mounting workpiece, the mounting workpiece comprises a mounting plate and an adjustable component, one end of the mounting plate is provided with a first hook portion, the mounting plate is hung on the Larsen steel sheet pile through the first hook portion, the adjustable component is arranged on the side of the mounting plate away from the Larsen steel sheet pile, the purlin support is connected with the mounting plate through the adjustable component and can be adjusted in height along the length direction of the mounting plate.

3. The bridge abutment foundation pit support structure suitable for space restriction according to claim 2, characterized in that, The adjustable component comprises two oppositely arranged L-shaped members, both the L-shaped members extend along the length direction of the mounting plate, and the L-shaped members and the mounting plate form a T-shaped sliding groove, the connecting assembly further comprises a sliding block matched with the sliding groove, the sliding block is connected with the purlin support, and the sliding block and the L-shaped member are connected through a positioning member.

4. The bridge abutment foundation pit support structure suitable for space restriction according to claim 3, characterized in that, The L-shaped member is provided with a plurality of first positioning holes along the length direction, the sliding block is provided with a second positioning hole matched with the first positioning hole, and the positioning member connects the sliding block and the L-shaped member by sequentially penetrating the first positioning hole and the second positioning hole.

5. The bridge abutment foundation pit support structure suitable for space restriction according to claim 3, wherein, The purlin support comprises a transverse bearing plate, a vertical connecting plate and an inclined stiffening plate, the vertical connecting plate is connected perpendicularly to one side of the transverse bearing plate, and the inclined stiffening plate is connected perpendicularly to the bottom surface of the transverse bearing plate; a clamping groove matched with the surrounding purlin is formed between the transverse bearing plate, the vertical connecting plate and the L-shaped member.

6. The bridge abutment foundation pit support structure suitable for space restriction according to claim 1, wherein, The support assembly comprises a steel support and two second hook portions, the two second hook portions are connected to the two ends of the steel support respectively, and each second hook portion is hung on the adjacent surrounding purlin.

7. The bridge abutment foundation pit support structure suitable for space restriction according to claim 1, wherein, The soil cofferdam is backfilled with cohesive soil, and the compaction degree of the backfill is greater than or equal to 85%.

8. The bridge abutment foundation pit support structure suitable for space restriction according to claim 1, wherein, An impermeable composite geomembrane is laid on one side of the soil cofferdam.

9. The bridge abutment foundation pit support structure suitable for space restriction according to claim 1, wherein, The steel sheet pile, the surrounding purlin and the purlin support are made of Q235 material.

10. The bridge abutment foundation pit support structure suitable for space restriction according to claim 6, wherein, The steel support is made of a Q235 steel pipe with a diameter of 609 mm and a wall thickness of 12 mm.

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