Detachable locking beam structure for open excavation of soil-rock combined stratum and its construction method

Abstract

A detachable locking foot beam structure for an open excavation in a soil-rock combination stratum and a construction method thereof, wherein the structure comprises bored cast-in-place piles for the foundation pit in an upper soft stratum, pre-cracked steel pipe piles for the foundation pit in a lower hard stratum, anchor cables, anchor rods, a secondary lining structure and locking foot beams. The locking foot beams are prefabricated components cast as a whole using an integrated construction technology, which can be customized and mass-produced according to different engineering requirements and can be reused in engineering construction. Thus, the present invention introduces the concept of green, low-carbon and environmentally friendly construction into the construction technology of underground engineering structures. The prefabricated components are of safe and reliable quality and are detachable, easy to install, and can be mass-produced at a low cost. The problems of difficulty in tying steel bars of locking foot beams on site, difficulty in pouring concrete, time-consuming maintenance, inability to recycle locking foot beams and high engineering costs during underground engineering construction are solved. The present invention is particularly suitable for large-scale underground engineering construction. The detachable and recyclable locking foot beams greatly reduce engineering costs and save construction period.

Description

Technical Field

[0001] The present invention relates to the technical field of subway construction engineering, and more particularly to a detachable locking foot beam structure for an open excavation foundation pit in a soil-rock combined stratum and a construction method thereof. Background Art

[0002] Prefabricated buildings are structures assembled on-site from prefabricated components. The development of prefabricated buildings represents a significant shift in construction methods and is a mainstream initiative being vigorously promoted by the government. Prefabrication contributes to resource conservation and energy conservation, reduces construction pollution, improves labor productivity and quality and safety, and promotes the deep integration of the construction industry with information-based industrialization. In recent years, underground engineering construction in my country has experienced explosive growth, but the majority of construction methods still rely on cast-in-place construction. The proportion and scale of prefabricated buildings remain low, significantly lagging behind the requirements for green building development and advanced construction methods.

[0003] At present, all the lock-foot beams used in the support of open excavation foundation pits for soil-rock combinations are cast-in-place reinforced concrete lock-foot beams. In underground engineering construction, timely support is crucial to the safety of the foundation pit. At the same time, the scale of underground engineering construction is getting larger and larger, and the important role of the economic and time benefits of using detachable prefabricated structures has been further highlighted.

[0004] To this end, the inventors of the present invention proposed the use of detachable assembled locking beams for the layered support method of soil-rock combination strata, which reduced the amount of masonry work and the number of operators on site, facilitated the management of on-site personnel and construction periods, and at the same time, the standardized engineering prefabricated components had better quality. After the project was completed, the locking beams were recycled, which greatly reduced the construction cost and saved materials. Summary of the Invention

[0005] Therefore, the purpose of the present invention is to provide a detachable locking foot beam structure and a construction method for an open excavation foundation pit in a soil-rock combination stratum, which can solve the defects of the existing technology, provide a reusable detachable locking foot beam, and solve the problem that the locking foot beam cannot be reused in the existing foundation pit construction.

[0006] To achieve the above-mentioned object, the present invention discloses a detachable locking foot beam structure for an open-cut foundation pit in a soil-rock combination stratum, comprising foundation pit retaining piles drilled from an upper soft stratum, foundation pit pre-cracked steel pipe piles in a lower hard stratum, multiple anchor cables, multiple anchor rods, a secondary lining structure, and an assembled locking foot beam. The multiple anchor cables are anchored to the foundation pit retaining piles to form a support structure for the upper soft foundation pit, and the foundation pit pre-cracked steel pipe piles are vertically arranged and anchored by multiple anchor rods to form a support structure for the lower hard foundation pit. The structure is characterized in that:

[0007] The assembled locking foot beam adopts a boot-shaped cross-section structure, which includes an upper right-angled trapezoidal structure and a lower rectangular structure. One side end face of the assembled locking foot beam is provided with a locking foot beam tenon, and the other side end face is provided with a locking foot beam tenon corresponding to the locking foot beam tenon, so that the two assembled locking foot beams can be docked and assembled by matching the locking foot beam tenon and the locking foot beam tenon, so as to connect different numbers of assembled locking foot beams to meet different length requirements, wherein a plurality of inclined trumpet-shaped hole steel sleeves are pre-embedded at equal intervals on the right-angled trapezoidal structure to facilitate the adjustment of the setting angle of the locking foot anchor cable, and a plurality of cylindrical hole steel sleeves are pre-embedded at equal intervals on the rectangular structure, wherein the trumpet-shaped hole steel sleeves and the cylindrical hole steel sleeves are integrally cast and formed into one piece on the assembled locking foot beam to form an integrated prefabricated part.

[0008] The length of the assembled locking foot beam is 4-8m, the height of the assembled locking foot beam is 800mm, the width of the assembled locking foot beam is 900mm, and the inclination angle of the inclined plane of the right-angled trapezoidal structure is ψ1=30~55°.

[0009] Among them, the bell-mouth hole steel casing is set in the locking foot anchor cable installation reserved hole on the inclined surface of the right-angled trapezoidal structure. The vertical distance between its hole and the top surface of the right-angled trapezoidal structure is h1=200mm, and the vertical distance from the bottom surface is h2=200mm. Therefore, the overall height of the right-angled trapezoidal structure is 400mm, and the height of the rectangular structure is h3=400mm. The inclination angle of the locking foot anchor cable installation reserved hole of the bell-mouth hole steel casing is ψ2=10~20°, so it is suitable for requirements and installation at different angles.

[0010] Among them, the wall thickness of the cylindrical hole steel casing is 5mm, and it is arranged in the steel pipe pile installation reserved hole on the rectangular structure. The distance L4 between the hole center of the steel pipe pile installation reserved hole and one side of the rectangular structure is 175mm, and the distance L5 between the other side is 725mm. The aperture of the steel pipe pile installation reserved hole is 150mm, and the spacing between the steel pipe pile installation reserved holes of each cylindrical hole steel casing is 1300mm~2000mm.

[0011] Wherein, the upper width L1 of the right-angled trapezoidal structure is 400 mm.

[0012] Among them, the wall thickness of the trumpet-shaped steel casing is 5mm, the length L6=465mm, and its structure is a trumpet-shaped one with a small top and a large bottom. The top radius r1=75mm and the bottom radius r2=110mm of the reserved hole for installing the locking foot anchor cable.

[0013] Also disclosed is a construction method for a detachable locking foot beam structure in an open excavation foundation pit in the soil-rock combination stratum as described above, which is characterized by comprising the following steps:

[0014] S1: measurement, layout and positioning;

[0015] S2: Construction of underground retaining pile structure for the upper open excavation pit;

[0016] S3: Excavate the upper foundation pit layer by layer to 500mm below the anchor cable installation position of each layer, install the anchor cables in time, and tension the anchor cables to the design value;

[0017] S4: When the foundation pit is excavated to the installation position of the locking foot beam, assemble the prefabricated locking foot beams in sequence, install the anchor cables, and tension the anchor cables to the design value;

[0018] S5: The drilling rig is in place, and the steel pipe pile drilling rig penetrates the pre-cracked steel pipe piles on the locking foot beam to install the reserved holes for the steel pipe piles in the lower foundation pit. After the holes are drilled and cleaned, the pre-cracked steel pipe piles are installed.

[0019] S6: Excavate the lower foundation pit in layers to 500mm below the anchor bolt installation position of each layer, and install the anchor bolts in time;

[0020] S7: After the foundation pit is bottomed out, the secondary lining waterproof layer is laid, the secondary lining steel bars are tied and concrete is poured;

[0021] S8: After the secondary lining structure is constructed to the appropriate position below the locking foot beam, the locking foot anchor cable is removed and the locking foot beam is recovered;

[0022] S9: Complete the construction of the remaining secondary lining structure.

[0023] Wherein, step S4 also includes the following sub-steps:

[0024] S401: Place the steel formwork for the locking foot beam and apply release agent on the inner surface of the formwork;

[0025] S402: Pre-installed holes for positioning locking anchor cables and pre-installed casings for steel pipe piles;

[0026] S403: Tie the reinforcement bars of the locking foot beam;

[0027] S404: Install the locking foot beam steel template. The steel template here uses a small template connected by a rotating hinge. Adjust the hinge according to the shape of the locking foot beam slope. After adjusting the shape of the locking foot beam, fix the hinge position.

[0028] S405: Install one side end mold, and use socket-type connection between the end mold and the top mold, bottom mold and side mold;

[0029] S406: Place the rubber inflatable core mold into the steel cage, fix the position, and connect the core mold with the surrounding formwork;

[0030] S407: After pouring the concrete, use a vibrating rod to vibrate from the vibrating opening reserved in the top form;

[0031] S408: After the concrete has initially set, the valve of the rubber inflatable core mold is opened to release the air, and then the mold is removed and the concrete component is cured.

[0032] In step S408 , the release agent is soap water formed by soap powder and water in a mass ratio of 1:20.

[0033] Therefore, the technical solution of the present invention has the following advantages:

[0034] (1) The assembled locking foot beam adopts prefabricated assembled components with reliable quality and precise size. It has the characteristics of low discreteness of component performance and fast assembly speed, which conforms to the principle of economy.

[0035] (2) The assembled locking foot beam adopts the mature mortise and tenon connection method, which is easy to install and disassemble, easy to operate and reliable in connection.

[0036] (3) The prefabricated locking foot beam is pre-installed with a steel pipe pile casing, which facilitates the construction positioning of the steel pipe pile, ensures the accuracy of the steel pipe pile construction position, and eliminates the situation where the steel pipe pile invades the interior of the foundation pit.

[0037] (4) The mounting holes of the assembled locking foot beam anchor cables are in a “trumpet-shaped” shape, which facilitates the installation of anchor cables at different driving angles and expands the scope of use of the locking foot beam.

[0038] (5) The assembled locking foot beam adopts a recyclable lightweight reinforced concrete structure, which can be recycled multiple times and meets the requirements of low carbon and environmental protection.

[0039] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0040] The present invention introduces a series of simplified concepts in the Summary of the Invention, which are further explained in detail in the Detailed Description of the Invention. This Summary of the Invention is not intended to define the key features or essential features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution. The following further describes the technical solution of the present invention in detail through the accompanying drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0042] Figure 1This is a construction step diagram of the construction method of the detachable locking foot beam structure for an open excavation foundation pit in a soil-rock combination stratum according to the present invention.

[0043] Figure 2 It is a schematic diagram of the detachable locking foot beam structure of the open excavation foundation pit in the soil-rock combination stratum of the present invention.

[0044] Figure 3 This is a rendering of the assembled locking foot beam of the present invention.

[0045] Figure 4 This is a cross-sectional view of a standard section of the assembled locking foot beam of the present invention.

[0046] Figure 5 This is a front view of the assembled locking foot beam of the present invention.

[0047] Figure 6 It is a rear view of the assembled locking foot beam of the present invention.

[0048] Figure 7 It is a left side view of the assembled locking foot beam of the present invention.

[0049] Figure 8 It is a right side view of the assembled locking foot beam of the present invention.

[0050] Figure 9 This is a cross-sectional view of a trumpet-shaped pre-set steel conduit according to the present invention.

[0051] Figure 10 This is a front view of the trumpet-shaped reserved hole pre-installed steel conduit of the present invention.

[0052] Reference numerals:

[0053] 1. Foundation pit retaining piles; 2. Secondary lining structure; 3. Prefabricated locking beam; 31. Locking beam tenon; 32. Locking beam concave tenon; 33. Trumpet-shaped hole steel casing; Cylindrical hole steel casing; 4. Anchor cable; 5. Anchor rod; 6. Foundation pit pre-cracked steel pipe piles. DETAILED DESCRIPTION

[0054] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments so that those skilled in the art can implement the invention with reference to the description.

[0055] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0056] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] like Figure 2As shown, the overall structure of the detachable locking foot beam structure of the open-cut foundation pit in the soil-rock combination stratum of the present invention is shown. In this structure, it includes foundation pit retaining piles 1 drilled from the upper soft stratum, foundation pit pre-cracked steel pipe piles 6 of the lower hard stratum, multiple anchor cables 4, multiple anchor rods 5, a secondary lining structure 2 and an assembled locking foot beam 3. The multiple anchor cables 4 are anchored to the foundation pit retaining piles 1 to form a support structure for the upper soft foundation pit. The foundation pit pre-cracked steel pipe piles 6 are vertically arranged and are anchored by multiple anchor rods 5 to form a support structure for the lower hard foundation pit.

[0058] like Figures 3 to 10 As shown, the assembled locking foot beam 1 adopts a boot-shaped cross-section structure, including an upper right-angled trapezoidal structure and a lower rectangular structure. One side end face of the assembled locking foot beam 3 is provided with a locking foot beam tenon 31, and the other side end face is provided with a locking foot beam tenon 32 corresponding to the locking foot beam tenon 31, so that the two assembled locking foot beams 3 can be docked and assembled through the locking foot beam tenon 31 and the locking foot beam tenon 32, so as to adapt to different length requirements by different connection numbers. A plurality of inclined trumpet-shaped hole steel sleeves 33 are pre-embedded at equal intervals on the right-angled trapezoidal structure to facilitate the adjustment of the setting angle of the locking foot anchor cable, and a plurality of cylindrical hole steel sleeves 34 are pre-embedded at equal intervals on the rectangular structure, wherein the trumpet-shaped hole steel sleeves 33 and the cylindrical hole steel sleeves 34 are integrally cast and formed in one piece on the assembled locking foot beam 3 to form an integrated prefabricated part.

[0059] Preferably, the length L of the assembled locking foot beam 3 is 4-8m, the height h of the assembled locking foot beam 3 is 800mm, the width L of the assembled locking foot beam 3 is 900mm, and the inclination angle ψ1 of the right-angled trapezoidal structure is 30~55°.

[0060] Preferably, the trumpet-shaped hole steel casing 33 is arranged on the inclined surface of the right-angled trapezoidal structure as a reserved hole for installing the locking foot anchor cable. The vertical distance between the hole and the top surface of the right-angled trapezoidal structure is h1=200mm, and the vertical distance between the hole and the bottom surface is h2=200mm. Therefore, the overall height of the right-angled trapezoidal structure can be 400mm, and the height of the rectangular structure is h3=400mm. The inclination angle ψ2 of the reserved hole for installing the locking foot anchor cable of the trumpet-shaped hole steel casing 33 is 10~20°, so that it is suitable for requirements and installation at different angles.

[0061] Preferably, the wall thickness of the cylindrical hole steel casing 34 is 5 mm, and it is arranged in the steel pipe pile installation reserved hole on the rectangular structure. The distance L4 between the hole center of the steel pipe pile installation reserved hole and one side of the rectangular structure is 175 mm, and the distance L5 between the hole center and the other side is 725 mm. The aperture of the steel pipe pile installation reserved hole is 150 mm, and the spacing between the steel pipe pile installation reserved holes of each cylindrical hole steel casing 34 is preferably 1300 mm to 2000 mm.

[0062] Preferably, the upper width L1 of the right-angled trapezoidal structure is 400 mm.

[0063] Preferably, if Figure 9 and Figure 10 As shown, the wall thickness of the bell-shaped steel casing 33 is 5 mm, the length L6 = 465 mm, and its structure is a bell-shaped one with a small top and a large bottom. The top radius r1 = 75 mm and the bottom radius r2 = 110 mm of the reserved hole for installing the locking foot anchor cable.

[0064] like Figure 1 As shown, the present invention also discloses a construction method of a detachable locking foot beam structure for an open excavation foundation pit in the soil-rock combination stratum as described above, which comprises the following steps:

[0065] S1: measurement, layout and positioning;

[0066] S2: Construction of underground retaining pile structure for the upper open excavation pit;

[0067] S3: Excavate the upper foundation pit layer by layer to 500mm below the anchor cable installation position of each layer, install the anchor cables in time, and tension the anchor cables to the design value;

[0068] S4: When the foundation pit is excavated to the installation position of the locking foot beam, assemble the prefabricated locking foot beams in sequence, install the anchor cables, and tension the anchor cables to the design value;

[0069] S5: The drilling rig is in place, and the steel pipe pile drilling rig penetrates the pre-cracked steel pipe piles on the locking foot beam to install the reserved holes for the steel pipe piles in the lower foundation pit. After the holes are drilled and cleaned, the pre-cracked steel pipe piles are installed.

[0070] S6: Excavate the lower foundation pit in layers to 500mm below the anchor bolt installation position of each layer, and install the anchor bolts in time;

[0071] S7: After the foundation pit is bottomed out, the secondary lining waterproof layer is laid, the secondary lining steel bars are tied and concrete is poured;

[0072] S8: After the secondary lining structure is constructed to the appropriate position below the locking foot beam, the locking foot anchor cable is removed and the locking foot beam is recovered;

[0073] S9: Complete the construction of the remaining secondary lining structure.

[0074] Wherein step S4 further includes the following sub-steps:

[0075] S401: Place the steel formwork for the locking foot beam and apply release agent on the inner surface of the formwork;

[0076] S402: Pre-installed holes for positioning locking anchor cables and pre-installed casings for steel pipe piles;

[0077] S403: Tie the reinforcement bars of the locking foot beam;

[0078] S404: Install the locking foot beam steel template. The steel template here uses a small template connected by a rotating hinge. Adjust the hinge according to the shape of the locking foot beam slope. After adjusting the shape of the locking foot beam, fix the hinge position.

[0079] S405: Install one side end mold, and use socket-type connection between the end mold and the top mold, bottom mold and side mold;

[0080] S406: Place the rubber inflatable core mold into the steel cage, fix the position, and connect the core mold with the surrounding formwork;

[0081] S407: After pouring the concrete, use a vibrating rod to vibrate from the vibrating opening reserved in the top form;

[0082] S408: After the concrete has initially set, the valve of the rubber inflatable core mold is opened to release the air, and then the mold is removed and the concrete component is cured.

[0083] In step S408 , the release agent is soap water formed by soap powder and water in a mass ratio of 1:20.

[0084] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0085] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0086] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A detachable locking beam structure for an open-cut foundation pit in a soil-rock combination stratum, comprising foundation pit retaining piles drilled from an upper soft stratum, pre-cracked steel pipe piles in a lower hard stratum, multiple anchor cables, multiple anchor rods, a secondary lining structure, and an assembled locking beam. The multiple anchor cables are anchored to the foundation pit retaining piles to form a support structure for the upper soft foundation pit. The pre-cracked steel pipe piles are vertically arranged and anchored by multiple anchor rods to form a support structure for the lower hard foundation pit. The structure is characterized by: The assembled locking foot beam adopts a boot-shaped cross-section structure, which includes an upper right-angled trapezoidal structure and a lower rectangular structure. One end face of the assembled locking foot beam is provided with a locking foot beam tenon, and the other end face is provided with a locking foot beam tenon corresponding to the locking foot beam tenon, so that the two assembled locking foot beams can be butt-jointed and assembled by matching the locking foot beam tenon and the locking foot beam tenon, so as to connect different numbers of assembled locking foot beams to meet different length requirements, wherein a plurality of inclined trumpet-shaped hole steel sleeves are pre-embedded at equal intervals on the right-angled trapezoidal structure to facilitate the adjustment of the setting angle of the locking foot anchor cable, and a plurality of cylindrical hole steel sleeves are pre-embedded at equal intervals on the rectangular structure, wherein the trumpet-shaped hole steel sleeves and the cylindrical hole steel sleeves are integrally cast and formed integrally on the assembled locking foot beam to form an integrated prefabricated part; The bell-shaped hole steel casing is provided with a reserved hole for installing a locking foot anchor cable on the inclined surface of the right-angled trapezoidal structure. The vertical distance between the hole and the top surface of the right-angled trapezoidal structure is h1=200mm, and the vertical distance from the bottom surface is h2=200mm. Therefore, the overall height of the right-angled trapezoidal structure is 400mm, and the height of the rectangular structure is h3=400mm. The inclination angle ψ2 of the reserved hole for installing the locking foot anchor cable of the bell-shaped hole steel casing is 10~20°, so as to be applicable to requirements and installation at different angles; The wall thickness of the cylindrical hole steel casing is 5 mm. It is arranged in the steel pipe pile installation reserved hole on the rectangular structure. The distance L4 between the center of the steel pipe pile installation reserved hole and one side of the rectangular structure is 175 mm, and the distance L5 between the center and the other side is 725 mm. The diameter of the steel pipe pile installation reserved hole is 150 mm. The spacing between the steel pipe pile installation reserved holes of each cylindrical hole steel casing is 1300 mm to 2000 mm. The assembled locking foot beam adopts the mature mortise and tenon connection method, which is convenient for installation and disassembly, easy to operate, and reliable in connection. The pre-installed steel pipe pile casing facilitates the construction positioning of the steel pipe pile, ensures the accuracy of the steel pipe pile construction position, and eliminates the situation where the steel pipe pile invades the interior of the foundation pit.

2. The detachable locking foot beam structure for open excavation of soil-rock combination strata according to claim 1 is characterized in that: The length of the assembled locking foot beam is 4-8m, the height of the assembled locking foot beam is 800mm, the width of the assembled locking foot beam is 900mm, and the inclination angle ψ1 of the right-angled trapezoidal structure is 30-55°.

3. The detachable locking foot beam structure for open excavation of soil-rock combination strata according to claim 1 is characterized in that: The upper width L1 of the right-angled trapezoidal structure is 400 mm.

4. The detachable locking foot beam structure for open excavation of soil-rock combination strata according to claim 1 is characterized in that: The wall thickness of the bell-mouth steel casing is 5 mm, and the length L6 is 465 mm. Its structure is a bell-mouth shape with a small top and a large bottom. The top radius r1 of the reserved hole for installing the locking foot anchor cable is 75 mm, and the bottom radius r2 is 110 mm.

5. A construction method for a detachable locking foot beam structure in an open excavation foundation pit in a soil-rock combination stratum as described in any one of claims 1 to 4, characterized in that The following steps are included: S1: measurement, layout and positioning; S2: Construction of underground retaining pile structure for the upper open excavation pit; S3: Excavate the upper foundation pit layer by layer to 500mm below the anchor cable installation position of each layer, install the anchor cables in time, and tension the anchor cables to the design value; S4: When the foundation pit is excavated to the installation position of the locking foot beam, the assembled locking foot beam is assembled in sequence, the anchor cable is installed, and the anchor cable prestressing is tensioned to the design value, which also includes the following sub-steps: S401: Place the steel formwork for the locking foot beam and apply release agent on the inner surface of the formwork; S402: Pre-installed holes for positioning locking anchor cables and pre-installed casings for steel pipe piles; S403: Tie the reinforcement bars of the locking foot beam; S404: Install the locking foot beam steel template. The steel template here uses a small template connected by a rotating hinge. Adjust the hinge according to the shape of the locking foot beam slope. After adjusting the shape of the locking foot beam, fix the hinge position. S405: Install one side end mold, and use socket-type connection between the end mold and the top mold, bottom mold and side mold; S406: Place the rubber inflatable core mold into the steel cage, fix the position, and connect the core mold with the surrounding formwork; S407: After pouring the concrete, use a vibrating rod to vibrate from the vibrating opening reserved in the top form; S408: After the concrete has initially set, the valve of the rubber inflatable core mold is opened to release air, and then the mold is removed and the concrete component is cured; S5: The drilling rig is in place, and the steel pipe pile drilling rig penetrates the pre-cracked steel pipe piles on the locking foot beam to install the reserved holes for the steel pipe piles in the lower foundation pit. After the holes are drilled and cleaned, the pre-cracked steel pipe piles are installed. S6: Excavate the lower foundation pit in layers to 500mm below the anchor bolt installation position of each layer, and install the anchor bolts in time; S7: After the foundation pit is bottomed out, the secondary lining waterproof layer is laid, the secondary lining steel bars are tied and concrete is poured; S8: After the secondary lining structure is constructed to the appropriate position below the locking foot beam, the locking foot anchor cable is removed and the locking foot beam is recovered; S9: Complete the construction of the remaining secondary lining structure.

6. The detachable locking foot beam structure for open excavation of soil-rock combination strata according to claim 5 is characterized in that: In step S408 , the release agent is soap water formed by soap powder and water in a mass ratio of 1:20.

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