Steel inclined strut foundation pit supporting structure suitable for mountain rock-soil layer and construction method

Abstract

The invention discloses a steel inclined strut foundation pit supporting structure suitable for a mountain rock-soil layer and a construction method, and relates to the field of foundation pit supporting. The structure comprises a steel lattice, row piles, cushion blocks, reinforcing piers, a bottom plate and triangular soil. The row piles are arranged along the edge of the foundation pit; the reinforcing piers are arranged at the tops of the row piles; the triangular soil is formed by excavating along the row piles; a bottom plate is arranged below the triangular soil; the cushion block is arranged below the cushion layer bottom of the bottom plate; the steel lattices are arranged in an inclined supporting mode, the higher ends of the steel lattices are embedded into the bevel edges of the reinforcing piers, and the lower ends of the steel lattices penetrate through the bottom plate and are embedded into the cushion blocks. The construction method comprises the steps that foundation pit edge row piles are constructed; the edge of the foundation pit is excavated to form excavation triangular soil, the excavation range adapts to the placement size needed by the steel lattice, and the shape of the triangular soil is adjusted according to fluctuation of a rock-soil layer on the mountain side; and a steel lattice structure and cushion blocks are constructed, and then a basement foundation is constructed. The steel lattice and the cast-in-place pile are combined, and the structure can be suitable for deep foundation pits with complex geology.

Description

Technical Field

[0001] The invention belongs to the field of foundation pit support, and in particular relates to a steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers and a construction method. Background Art

[0002] Foundation pit support refers to a series of temporary or semi-permanent retaining structure measures taken during the construction of building foundations to ensure soil stability and the safety of the surrounding environment. However, there is currently little research on the support forms for foundation pits with complex soil conditions, especially those with large undulations in mountain rock and soil layers.

[0003] Chinese patent CN115772901A (publication date: March 10, 2023) discloses a steel lattice inclined pile support construction method, which is to first process a three-section inclined support pile consisting of a crown beam connection section, a loading device and a rotary jet pile connection section according to the design, then drill a hole, build an inclined support pile below, construct an inclined pile body, and form an enlarged pile end at its lower end, then construct a crown beam and a reinforcement pier, and construct the crown beam, reinforcement pier and inclined support pile into an integral structure. After completion, a certain prestress is applied to the inclined support pile by adding a device, and finally excavation and pouring of the cushion layer are carried out. However, this method has high economic practicality and promotion value only in foundation pit projects with good soil conditions.

[0004] Chinese patent CN115045293A (publication date: September 13, 2022) discloses a vertical diagonal bracing structure for a deep foundation pit and a construction method thereof. The diagonal bracing force-bearing components are composed of steel lattice columns arranged at the top and prefabricated square piles arranged at the bottom, or are composed of steel pipe piles arranged at the top and prefabricated pipe piles arranged at the bottom, and the upper structure and the lower structure are fixedly connected. During construction, an oblique mixing pile machine is used to evenly mix the cement slurry and the foundation soil to form an oblique cement mixing pile. Before the oblique cement mixing pile solidifies, the oblique bracing force-bearing component is inserted along the guide frame. This method is only applicable to situations where the foundation pit conditions are good. The foundation soil needs to be evenly mixed to form an oblique cement mixing pile. It is also not suitable for situations where the mountain rock and soil layers have large undulations. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a steel diagonal brace foundation pit support structure and a construction method suitable for mountain rock and soil layers.

[0006] A steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers, the structure comprising a steel lattice structure, a row of piles, a cushion block, a reinforced pier, a bottom plate, and triangular soil;

[0007] The row of piles is arranged along the edge of the foundation pit; the reinforcing pier is arranged on the top of the row of piles in an inverted trapezoidal shape; the triangular soil is formed by excavating along the row of piles; a bottom plate is arranged under the triangular soil;

[0008] The cushion block is a cast-in-place plain concrete prism, which is arranged below the cushion layer of the base plate;

[0009] The steel lattice diagonal brace is arranged, with a higher end embedded in the oblique side of the reinforcing pier, and a lower end passing through the bottom plate and embedded in the pad.

[0010] Furthermore, the steel lattice is in the shape of a cuboid with a rectangular cross section, and includes long-side horizontal gussets, short-side horizontal gussets, inclined gussets, angle steels, and end plates;

[0011] The angle steel is a long steel strip with two sides perpendicular to each other and is arranged at the four long edges of the steel lattice structure; it bears axial force

[0012] The long side horizontal gussets and the inclined gussets are arranged at intervals on the two sides of the steel lattice rectangular parallelepiped with larger side areas;

[0013] The short side horizontal gussets correspond to the long side horizontal gussets and are parallel to the inclined gussets and are arranged on two side surfaces with smaller side areas of the steel lattice cuboid;

[0014] The end plates are connected to the ends of the steel lattice by high-strength bolts.

[0015] Furthermore, the foundation pit support structure is arranged at a location where the rock and soil layers on the side of the foundation pit have large fluctuations according to the requirements for the support of the upper structure;

[0016] The angle between the steel lattice and the bottom plate is 25°-50°.

[0017] Furthermore, the longitudinal section of one end of the bottom plate is widened to the bottom elevation of the foundation pedestal of the foundation pit, and is vertically connected to the cast-in-place piles through the bottom plate force transmission belt; a bottom plate water stop is provided at the connection position between the bottom plate and the steel lattice;

[0018] Furthermore, the triangular soil is arranged in a right trapezoidal shape below the steel lattice, and a concrete surface layer is sprayed on the surface of the triangular soil.

[0019] Furthermore, the row of piles is an interlocking row of piles, which is composed of a plurality of cast-in-place piles and plain concrete piles arranged at intervals.

[0020] A construction method for a steel diagonal brace foundation pit support structure suitable for a mountain rock layer, comprising the following steps:

[0021] S1. Use soft cutting method to construct the interlocking piles at the edge of the foundation pit. Test piles are carried out before formal construction. During construction, plain concrete piles are constructed first, followed by cast-in-place piles, and reinforced piers are set on top. Construction must be continuous. After construction, low-strain dynamic testing method is used to detect the integrity of the pile body;

[0022] S2. Excavate the edge of the foundation pit to form a triangular soil excavation. The excavation range is adapted to the size required for the steel lattice structure to be placed, and the shape of the triangular soil is adjusted to adapt to the ups and downs of the rock and soil layer on the side of the mountain;

[0023] S3. The steel lattice structure is connected by welding and high-strength bolts. The steel lattice is transported and installed above the triangular soil, and then a pad is poured at the lower end of the steel lattice to support and fix the steel lattice.

[0024] S4. After the construction of pads and steel lattice diagonal braces is completed and reaches 80% of the design strength, remove the reserved triangular soil and then construct the basement foundation and bottom plate force transmission belt.

[0025] Compared with the prior art, the technical solution of the present application has the following advantages and effects:

[0026] 1. The present invention provides a steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers. The structure does not require drilling and pouring concrete. It only needs to set the steel lattice diagonal brace and fix the support by pouring plain concrete pads. The foundation pit support structure has good stability and low construction difficulty, which can greatly speed up the construction speed of the foundation pit.

[0027] 2. The present invention provides a construction method for a steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers. By first excavating the earth to form a triangular soil and then installing the steel lattice, drilling and excavation in the geology with large undulations of the rock and soil layers near the side of the mountain is avoided, thereby greatly ensuring the safety of the foundation pit and the surrounding environment.

[0028] The above is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application so that it can be implemented in accordance with the contents of the specification, and to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following is a detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings as follows.

[0029] Based on the detailed description of the specific embodiments of the present application in combination with the accompanying drawings below, those skilled in the art will become more aware of the above and other objects, advantages and features of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings without creative work. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale.

[0031] Figure 1It is a schematic diagram of a steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers according to one embodiment of the present invention;

[0032] Figure 2 is a schematic diagram of a steel lattice structure according to an embodiment of the present invention;

[0033] Figure numerals: 1. Steel lattice; 2. Pile row; 3. Spacer block; 4. Reinforced pier; 5. Bottom plate; 6. Triangular soil; 7. Horizontal tie plate on long side; 8. Horizontal tie plate on short side; 9. Inclined tie plate; 10. Angle steel; 11. Bottom plate force transmission belt; 12. Bottom plate water stop. DETAILED DESCRIPTION

[0034] To make the purpose, technical scheme and advantages of the embodiment of the present application clearer, the technical scheme in the embodiment of the present application will be clearly and completely described below in conjunction with the drawings in the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all the embodiments. In the following description, specific details such as specific configurations and components are provided only to help fully understand the embodiments of the present application. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. In addition, for clarity and brevity, the description of known functions and structures is omitted in the embodiment. It should be understood that "one embodiment" or "this embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "one embodiment" or "this embodiment" appearing in various places throughout the specification may not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner.

[0035] In addition, the present application may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity, and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0036] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" in this article describes another type of association relationship between associated objects, indicating that there can be two relationships. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0037] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusions.

[0038] Example 1

[0039] This embodiment relates to a steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers, such as Figure 1 As shown, the structure includes a steel lattice 1, a row of piles 2, a cushion block 3, a reinforcement pier 4, a bottom plate 5, and a triangular soil 6;

[0040] The row of piles 2 is arranged along the edge of the foundation pit; the reinforcing pier 4 is arranged on the top of the row of piles 2 in an inverted trapezoidal shape; the triangular soil 6 is formed by excavating along the row of piles 2; a bottom plate 5 is arranged below the triangular soil 6;

[0041] The cushion block 3 is a cast-in-place plain concrete prism, which is arranged below the cushion layer of the base plate 5;

[0042] The steel lattice 1 is arranged with diagonal braces, with a higher end embedded in the oblique side of the reinforcing pier 4 , and a lower end passing through the bottom plate 5 and embedded in the cushion block 3 .

[0043] Further, such as Figure 2 As shown, the steel lattice 1 is in the shape of a cuboid with a rectangular cross section, and includes a long side horizontal gusset plate 7, a short side horizontal gusset plate 8, an inclined gusset plate 9, an angle steel 10, and an end plate;

[0044] The angle steel 10 is a long steel strip with two sides perpendicular to each other and formed into an angle, and is arranged at the four long edges of the steel lattice 1 to bear the axial force.

[0045] The long side horizontal gusset plates 7 and the inclined gusset plates 9 are arranged at intervals on two side surfaces of the steel lattice structure 1 with larger side areas to resist lateral forces.

[0046] The short side horizontal gussets 8 are arranged on two side surfaces with smaller side areas of the rectangular parallelepiped of the steel lattice 1 in parallel with the long side horizontal gussets 7 and the inclined gussets 9;

[0047] The end plate is connected to the end of the steel lattice 1 by high-strength bolts.

[0048] The foundation pit of this embodiment adopts 600H×400 steel lattice 1 diagonal brace. The steel lattice 1 diagonal brace angle steel and tie plate steel are made of Q235B, the angle steel joints are welded by split penetration welding, each joint is staggered by 500mm, the tie plate and the angle steel are welded by circumference welding, both ends of the steel lattice 1 are welded to the end plate, the weld height is 8mm, and the weld grade is level three.

[0049] Furthermore, the foundation pit support structure is arranged at a location where the rock and soil layers on the side of the foundation pit have large fluctuations according to the requirements for the support of the upper structure;

[0050] The angle between the steel lattice 1 and the bottom plate 5 is 25°.

[0051] Furthermore, the longitudinal section of one end of the bottom plate 5 is widened to the bottom elevation of the foundation pedestal of the foundation pit, and is vertically connected to the cast-in-place piles 2 through a bottom plate force transmission belt 11; a bottom plate water stop 12 is provided at the connection portion between the bottom plate 5 and the steel lattice 1.

[0052] Furthermore, the triangular soil 6 is arranged in a regular trapezoidal shape below the steel lattice 1, and a concrete surface layer is sprayed on the surface of the triangular soil 6.

[0053] The shotcrete surface layer uses C20 shotcrete with a thickness of 80mm and is constructed in two layers: the first layer of shotcrete is 40-50mm thick and PO42.5 cement is used. During the rainy season, 3-5% S water reducer should be added.

[0054] The row of piles 2 is an interlocking row of piles 2, which is composed of a plurality of cast-in-place piles and plain concrete piles arranged at intervals.

[0055] The technical effect of this embodiment is as follows: the triangular soil is excavated in advance, and the steel lattice is combined with the pad, so as to realize the support of the foundation pit in the foundation pit with large undulations of the rock and soil layer near the mountain side.

[0056] Example 2

[0057] This embodiment relates to a steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers, the structure comprising a steel lattice 1, a row of piles 2, a cushion block 3, a reinforcement pier 4, a bottom plate 5, and a triangular soil 6;

[0058] The row of piles 2 is arranged along the edge of the foundation pit; the reinforcing pier 4 is arranged on the top of the row of piles 2 in an inverted trapezoidal shape; the triangular soil 6 is formed by excavating along the row of piles 2; a bottom plate 5 is arranged below the triangular soil 6;

[0059] The cushion block 3 is a cast-in-place plain concrete prism, which is arranged below the cushion layer of the base plate 5;

[0060] The steel lattice 1 is arranged with diagonal braces, with a higher end embedded in the oblique side of the reinforcing pier 4 , and a lower end passing through the bottom plate 5 and embedded in the cushion block 3 .

[0061] Further, such as Figure 2 As shown, the steel lattice 1 is in the shape of a cuboid with a rectangular cross section, and includes a long side horizontal gusset plate 7, a short side horizontal gusset plate 8, an inclined gusset plate 9, an angle steel 10, and an end plate;

[0062] The angle steel 10 is a long steel strip with two sides perpendicular to each other and formed into an angle, and is arranged at the four long edges of the steel lattice 1 to bear the axial force.

[0063] The long side horizontal gusset plates 7 and the inclined gusset plates 9 are arranged at intervals on two side surfaces of the steel lattice structure 1 with larger side areas to resist lateral forces.

[0064] The short side horizontal gussets 8 are arranged on two side surfaces with smaller side areas of the rectangular parallelepiped of the steel lattice 1 in parallel with the long side horizontal gussets 7 and the inclined gussets 9;

[0065] The end plate is connected to the end of the steel lattice 1 by high-strength bolts.

[0066] The foundation pit of this embodiment adopts 600H×400 steel lattice 1 diagonal brace. The steel lattice 1 diagonal brace angle steel and tie plate steel are made of Q235B, the angle steel joints are welded by split penetration welding, each joint is staggered by 500mm, the tie plate and the angle steel are welded by circumference welding, both ends of the steel lattice 1 are welded to the end plate, the weld height is 8mm, and the weld grade is level three.

[0067] Furthermore, the foundation pit support structure is arranged at a location where the rock and soil layers on the side of the foundation pit have large fluctuations according to the requirements for the support of the upper structure;

[0068] The angle between the steel lattice 1 and the bottom plate 5 is 25°.

[0069] Furthermore, the longitudinal section of one end of the bottom plate 5 is widened to the bottom elevation of the foundation pedestal of the foundation pit, and is vertically connected to the cast-in-place piles 2 through a bottom plate force transmission belt 11; a bottom plate water stop 12 is provided at the connection portion between the bottom plate 5 and the steel lattice 1.

[0070] Furthermore, the triangular soil 6 is arranged in a regular trapezoidal shape below the steel lattice 1, and a concrete surface layer is sprayed on the surface of the triangular soil 6.

[0071] The shotcrete surface layer uses C20 shotcrete with a thickness of 80mm and is constructed in two layers: the first layer of shotcrete is 40-50mm thick and PO42.5 cement is used. During the rainy season, 3-5% S water reducer should be added.

[0072] The row of piles 2 is an interlocking row of piles 2, which is composed of a plurality of cast-in-place piles and plain concrete piles arranged at intervals.

[0073] Technical effect of this embodiment: This embodiment sets the angle between the steel lattice and the bottom plate surface according to the upper structure and support requirements, so as to achieve flexible support for foundation pits with complex geology.

[0074] Example 3

[0075] This embodiment provides a construction method for a steel diagonal brace foundation pit support structure suitable for a mountain rock and soil layer in the above embodiment, comprising the following steps:

[0076] S1. Use soft cutting method to construct the edge of the foundation pit bite type pile row 3, including 800 rotary bored piles with reinforcement piles and 800 plain concrete piles without reinforcement piles. Test piles are carried out before formal construction. The concrete grade of the plain concrete piles is C20. The plain concrete piles use super slow setting concrete, and the slow setting time shall not be less than 60h.

[0077] The bored cast-in-place piles and plain concrete piles should be constructed with separate piles. The plain concrete piles should be constructed first, followed by the cast-in-place piles. The cast-in-place piles should be constructed within 48 hours after the plain concrete piles are constructed to ensure the overlap thickness of the plain concrete piles and cast-in-place piles. The pile position deviation should not exceed 50mm in both the axial and vertical axial directions, the verticality deviation should not exceed 0.5%, and the filling coefficient should be 1.05-1.10. The thickness of the pile bottom sediment should not exceed 100mm.

[0078] The over-filling height of the rotary pile is 800mm, the pile top extends into the reinforced pier 5 by 50mm, and the steel bar is anchored into the reinforced pier 5 for 30d. Before the construction of the reinforced pier 5, the floating slurry on the top of the retaining pile should be chiseled off, and the residue and floating soil should be cleaned up to ensure that the concrete strength of the pile top after the pile is chiseled reaches the design value.

[0079] Continuous construction is necessary, and after construction, the integrity of the pile body should be tested using the low-strain dynamic measurement method.

[0080] S2, excavating the edge of the foundation pit to form a triangular soil 6, the excavation range is adapted to the size required for the steel lattice, and the shape of the triangular soil 6 is adjusted to the undulation of the rock and soil layer on the side of the mountain, and spraying concrete surface layer;

[0081] The sprayed concrete surface layer above the triangular soil 14 adopts C20 sprayed concrete with a thickness of 80mm, and is constructed in two layers: the first layer of sprayed concrete is 40-50mm thick, and then the steel mesh is tied and the second layer of concrete is sprayed to the designed thickness. PO42.5 cement is used, and 3-5% S water reducer should be added during construction in the rainy season.

[0082] After the spraying is completed, the on-site test block strength test of the sprayed concrete surface layer shall be carried out. The number of tests for every 500 square meters of sprayed concrete area shall not be less than one group, and each group of test blocks shall not be less than 3. The thickness shall also be tested. The number of inspections shall not be less than one group per 500 square meters, and each group shall not be less than 3 points. The average thickness of the surface layer at all test points shall not be less than the designed thickness value, and the minimum thickness shall not be less than 80% of the designed thickness value.

[0083] S3, the steel lattice 1 structure is connected by welding and high-strength bolts, the steel lattice is transported and installed above the triangular soil 6, and then a pad 3 is poured at the lower end of the steel lattice to support and fix the steel lattice;

[0084] The pad is cast in one go and no construction joints are allowed.

[0085] After the construction of S4, pads 3 and steel lattice 1 diagonal braces is completed and reaches 80% of the design strength, the reserved triangular soil 6 is excavated, and then the basement foundation and bottom plate force transmission belt 11 are constructed.

[0086] After the installation of the inclined brace, the deformation should be monitored at least once a day.

[0087] The construction and installation of the diagonal brace should strictly control the plane position, angle and other parameters, and avoid the engineering piles. The allowable deviation of the diagonal brace installation: a. The elevation deviation of the diagonal brace center is not more than 30mm; b. The elevation difference between the two ends of the diagonal brace component is not more than 20mm; c. The horizontal axis deviation of the diagonal brace is not more than 30mm.

[0088] Technical effect of this embodiment: This method fully considers the situation of complex geological deep foundation pits, and ensures the performance of the support structure and construction efficiency by considering multiple aspects such as structural manufacturing methods, connection forms, and installation effect detection.

[0089] The above description is only the preferred embodiment of the present invention, which does not limit the protection scope of the present invention. For those skilled in the art, the present invention can be modified and varied in various ways. Within the spirit and principle of the present invention, any change, modification, replacement, integration and parameter change of these embodiments by conventional substitution or capable of achieving the same function without departing from the principle and spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers, characterized in that: The structure comprises a steel lattice (1), a row of piles (2), a cushion block (3), a reinforcement pier (4), a bottom plate (5), and triangular soil (6); The row of piles (2) is arranged along the edge of the foundation pit; the reinforcing pier (4) is arranged in an inverted trapezoidal shape on the top of the row of piles (2); the triangular soil (6) is formed by excavating along the row of piles (2); a bottom plate (5) is arranged below the triangular soil (6); The cushion block (3) is a cast-in-place plain concrete prism, and is arranged below the cushion layer of the base plate (5); The steel lattice structure (1) is arranged with diagonal braces, with a higher end embedded in the oblique side of the reinforcing pier (4), and a lower end passing through the bottom plate (5) and embedded in the cushion block (3).

2. The steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers according to claim 1 is characterized in that: The steel lattice (1) is in the shape of a cuboid with a rectangular cross section, and comprises long-side horizontal gussets (7), short-side horizontal gussets (8), inclined gussets (9), angle steels (10), and end plates; The angle steel (10) is a long steel strip with two sides perpendicular to each other and formed into an angle, and is arranged at the four long edges of the steel lattice (1); The long side horizontal gussets (7) and the inclined gussets (9) are arranged at intervals on two side surfaces of the steel lattice structure (1) with larger side areas; The short side horizontal gussets (8) are arranged on two side surfaces of the rectangular parallelepiped of the steel lattice (1) with smaller side areas, corresponding to the long side horizontal gussets (7) and parallel to the inclined gussets (9); The end plate is connected to the end of the steel lattice (1) by high-strength bolts.

3. A steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers according to claim 1 or 2, characterized in that: The foundation pit support structure is set up at the place where the rock and soil layer on the side of the mountain has large fluctuations according to the requirements of the upper structure support; The angle between the steel lattice (1) and the bottom plate (5) is 25°-50°.

4. The steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers according to claim 1 is characterized in that: The longitudinal section of one end of the bottom plate (5) is widened to the bottom elevation of the foundation pedestal of the foundation pit and is vertically connected to the cast-in-place pile (2) via a bottom plate force transmission belt (11); a bottom plate water stop plate (12) is provided at the connection portion between the bottom plate (5) and the steel lattice (1).

5. The steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers according to claim 1 is characterized in that: The triangular soil (6) is arranged in a regular trapezoidal shape below the steel lattice (1), and a concrete surface layer is sprayed on the surface of the triangular soil (6).

6. The steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers according to claim 1, characterized in that: The row of piles (2) is an interlocking row of piles (2), which is composed of a plurality of cast-in-place piles and plain concrete piles arranged at intervals.

7. A construction method for a steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers, for a steel diagonal brace foundation pit support structure suitable for mountain rock and soil layers as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Use soft cutting method to construct the edge of the foundation pit bite type pile row (2), and conduct trial pile before formal construction. During the construction, first construct the plain concrete pile, then construct the cast-in-place pile (2), and set the reinforcement pier (4) on top. The construction must be continuous. After the construction, use the low strain dynamic measurement method to detect the integrity of the pile body; S2, excavating the edge of the foundation pit to form an excavated triangular soil (6), the excavation range is adapted to the size required for the steel lattice to be placed, and the shape of the triangular soil (6) is adjusted to the undulation of the rock and soil layer on the side of the mountain, and spraying concrete surface layer; S3, the steel lattice (1) structure is connected by welding and high-strength bolts, the steel lattice is transported and installed above the triangular soil (6), and then a pad (3) is poured at the lower end of the steel lattice to support and fix the steel lattice; After the construction of S4, pads (3) and steel lattice (1) diagonal bracing is completed and reaches 80% of the design strength, the reserved triangular soil (6) is excavated, and then the basement foundation and bottom plate force transmission belt (11) are constructed.

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