A kind of underground structure coping bracket considering the counterpressure of enclosure structure

Abstract

This application belongs to the field of building component technology and relates to a coping bracket for underground structures that considers the counter-pressure effect of the retaining structure. The coping bracket of this application integrates the main structure and the retaining structure, taking into account the self-weight and lateral friction of the retaining structure. It fully utilizes the pull-out resistance of the retaining structure, reducing the use of anti-buoyancy measures such as pull-out piles and anti-buoyancy anchors, thus lowering project costs and achieving significant economic and social benefits. Simultaneously, this application does not compromise the waterproof sealing and integrity of the underground main structure, nor does it affect subsequent concrete pouring procedures; the force transmission method is simple and clear. The use of Z-shaped and H-shaped steel internal stiffening plates enhances the local stability of the H-shaped steel bracket web. The one-time integral pouring of the top of the retaining structure and the top of the main structure with the coping bracket eliminates the safety hazards of only considering the shear resistance of the bracket concrete and steel reinforcement, improving the overall strength, stiffness, and stability of the coping bracket joint.

Description

Technical Field

[0001] This application relates to the field of building component technology, and in particular to a coping bracket for underground structures that takes into account the counter-pressure effect of the enclosure structure. Background Technology

[0002] With the development and utilization of urban underground space, the buoyancy problem of underground structures has gradually become prominent. After the foundation is completed, the groundwater level gradually returns to normal over time, generating significant buoyancy on the foundation, especially in areas with high groundwater levels and saturated soil layers. If severe weather events, such as torrential rains or continuous rainfall, cause urban flooding, the buoyancy of underground structures will increase dramatically in the short term. Therefore, the buoyancy resistance of underground structures requires serious attention. Furthermore, for underground structures with deep excavations and large project volumes, the appropriateness of buoyancy resistance measures will affect the enormous project cost; overly conservative buoyancy resistance designs will result in significant waste.

[0003] Currently, there are two calculation methods for the anti-buoyancy design of underground structures where the main structure and retaining structure are integrated: one that does not consider the effect of side skin friction, and one that does consider it. When side skin friction is not considered, it is treated as a safety reserve for uplift resistance in the underground structure. However, this can lead to significant waste, mainly because the contact area between the retaining structure and the surrounding soil is large in anti-buoyancy design. Furthermore, if uplift piles are required in the underground structure, they must undergo a certain amount of uplift deformation to function. However, long-term monitoring of existing underground structures shows that most underground structures experience settlement during normal use, and even under high water levels, significant uplift deformation is rarely observed. This means that the retaining structure may exert considerable uplift resistance, and the installed uplift piles are actually used as compression piles in most cases. Therefore, this design method is too conservative. When side skin friction is considered, it is treated as a system along with the retaining structure, uplift piles, and counterweights to jointly resist buoyancy. This is an inevitable trend with the continuous improvement of underground engineering calculation theories and methods, and it is also an effective measure to reduce project costs. Therefore, it is necessary to consider the side friction resistance of the retaining structure in the anti-buoyancy design of underground structures, while also ensuring economic benefits. If pile support is used for the foundation pit, it is extremely crucial and important to design and study nodes that clearly and simply consider the side friction resistance of the retaining structure without compromising the waterproofing and integrity of the underground main structure, without affecting the subsequent concrete pouring and force transfer. Summary of the Invention

[0004] This application provides a capping bracket for underground structures that takes into account the counter-pressure effect of the retaining structure, which solves the problems of unclear force transmission path and force bearing mode of conventional counter-pressure brackets and damage to the sealing and integrity of the waterproofing of the underground main structure.

[0005] The technical solution adopted in this application is as follows:

[0006] A type of coping bracket for underground structures considering the counter-pressure effect of the retaining structure, comprising:

[0007] Retaining piles;

[0008] The pre-embedded steel bars are embedded in the interior of the retaining pile, and the upper part of the pre-embedded steel bars protrudes from the upper surface of the retaining pile.

[0009] The top pressure-bearing steel plate is installed on top of the underground main structure;

[0010] H-beam bracket, wherein the H-beam bracket has through holes for inserting the pre-embedded reinforcing bars, one end of the H-beam bracket is fixedly connected to the pre-embedded reinforcing bars through the through holes, and the other end of the H-beam bracket is fixedly connected to the top pressure plate;

[0011] A closed-loop waterproof layer is installed on the exterior facade of the underground main structure.

[0012] Optionally, it also includes bolts, the ends of the pre-embedded steel bars are threaded, and one end of the H-shaped steel bracket is fixedly connected to the end of the pre-embedded steel bars by bolts.

[0013] Optional components also include channel steel assemblies and steel plates on top of retaining piles;

[0014] The end of the H-beam bracket that connects to the top pressure plate is bent downwards;

[0015] The channel steel assembly consists of two C-shaped steels arranged back to back;

[0016] The steel plate on top of the retaining pile is laid on the top of the retaining pile. The upper end of the channel steel assembly supports the lower end face of one end of the H-shaped steel bracket. The lower end of the channel steel assembly is fixedly connected to the steel plate on top of the retaining pile.

[0017] Optionally, the channel steel assembly, the H-beam corbel, and the top steel plate of the retaining pile are all fixedly connected by welding.

[0018] Optionally, it also includes a reinforced concrete layer with inter-pile mesh, which is set between the soil between the retaining piles and the closed waterproof layer.

[0019] Optionally, internal stiffening plates and external stiffening plates for H-beams are also included;

[0020] The internal stiffening plate of the H-beam is Z-shaped and is set between the upper and lower flanges of the H-beam. The internal stiffening plate of the H-beam is fixedly connected to the upper and lower flanges of the H-beam.

[0021] The external stiffening plate of the H-beam is disposed on the lower surface of the lower flange of the H-beam, and both ends of the external stiffening plate are fixedly connected to the lower flange of the H-beam.

[0022] Optional features also include water-swellable sealing strips;

[0023] The water-swellable waterproofing strip is installed at the corner of the closed waterproof layer.

[0024] Optionally, the embedded steel bars include two rows of embedded steel bars arranged along the axial direction of the retaining pile, and the two rows of embedded steel bars are arranged in parallel on both radial sides of the retaining pile.

[0025] Optionally, in the two rows of pre-embedded steel bars, the number of pre-embedded steel bars in each row is 3.

[0026] The beneficial effects of adopting the technical solution of this application are as follows:

[0027] The underground structure of this application, which considers the counter-pressure effect of the retaining structure, includes: retaining piles; embedded reinforcing bars, the lower part of which is embedded inside the retaining piles, and the upper part of which protrudes from the upper surface of the retaining piles; a top pressure-bearing steel plate, set on top of the underground main structure; an H-shaped steel bracket, with through holes for housing the embedded reinforcing bars, one end of which is fixedly connected to the embedded reinforcing bars through the through holes, and the other end of which is fixedly connected to the top pressure-bearing steel plate; and a closed waterproof layer, set on the exterior facade of the underground main structure. As can be seen from the above structure, this application does not damage the sealing and integrity of the underground main structure's waterproofing, does not affect subsequent concrete pouring construction, and the force transfer method of this application is simple and clear; it possesses the following advantages:

[0028] 1. In the anti-buoyancy design, the main structure and the retaining structure are integrated and the side friction resistance of the retaining structure is considered. This can make full use of the pull-out resistance of the retaining structure, reduce the use of anti-buoyancy measures such as pull-out piles and anti-buoyancy anchors, reduce the project cost, and have obvious economic and social benefits.

[0029] 2. The Z-shaped H-beam internal stiffening plate enhances the local stability of the H-beam corbel web.

[0030] 3. The one-time integral casting of the top of the retaining structure and the top of the main structure with the counterweight bracket eliminates the safety hazards of only considering the shear resistance of the bracket concrete and steel bars, and improves the overall strength, stiffness and stability of the counterweight bracket joint.

[0031] 4. Through the optimization and improvement of conventional counter-pressure corbels, the design and construction of coping corbels for underground structures considering the counter-pressure effect of retaining structures are provided as a reference, and have great prospects for promotion and application. Attached Figure Description

[0032] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A schematic diagram of a structure provided for one embodiment of this application;

[0034] Figure 2 This is a schematic diagram of the structure of the H-beam steel bracket in the embodiments of this application;

[0035] Figure 3 This is a schematic diagram of another embodiment of the present application;

[0036] Figure 4 This is a cross-sectional view of one embodiment of this application;

[0037] Figure 5 This is a cross-sectional view of another embodiment of this application;

[0038] Figure 6 This is a cross-sectional view of yet another embodiment of this application;

[0039] Illustration:

[0040] Among them, 1-retaining pile, 2-underground main structure, 3-embedded steel bar, 4-top pressure steel plate, 5-H-shaped steel bracket, 51-web plate, 52-wing plate, 6-through hole, 7-closed waterproof layer, 8-bolt, 9-channel steel group, 91-C-shaped steel, 10-retaining pile top steel plate, 11-inter-pile mesh reinforced concrete layer, 12-H-shaped steel inner stiffening plate, 13-H-shaped steel outer stiffening plate, 14-water-swellable waterstop strip, 15-pouring concrete. Detailed Implementation

[0041] The embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described below do not represent all embodiments consistent with this application. They are merely examples of systems and methods consistent with some aspects of this application as detailed in the claims.

[0042] To facilitate a better understanding of this application, the technical names appearing in this application are explained below.

[0043] A corbel, also known as a beam bracket, is a support under a beam in a mixed structure. Its function is to disperse the force from the beam support to the underlying load-bearing structure because a concentrated force on one side is likely to damage the wall. In ancient architecture, the corbel is scientifically called a "bracket". In a cantilever system, there must be a connection structure between the hanging beam and the cantilever. Usually, the local structure at the cantilever end and the hanging beam end is called a corbel, also known as a beam bracket. The function of the corbel is to connect the cantilever beam and the hanging beam and transfer the load from the hanging beam. Here, due to the overlapping of the beams, a force transfer support needs to be set in the middle to transfer large vertical and horizontal reaction forces. Therefore, the height of the corbel has been reduced to less than half of the beam height, but it still has to transfer large vertical and horizontal reaction forces, making it a weak part of the upper structure.

[0044] Channel steel is a long steel bar with a grooved cross-section. It belongs to carbon structural steel for construction and machinery and is a section steel with a complex cross-section, whose cross-sectional shape is grooved. Channel steel is mainly used in building structures, curtain wall projects, mechanical equipment, and vehicle manufacturing, etc. The above definition does not fully constitute a limitation to this application because obviously, the material of the channel steel can include any steel other than carbon structural steel, and materials such as composite steel and alloy steel are not excluded from the scope covered by the channel steel in this application.

[0045] The exterior facade refers to the interface where an object directly contacts the external space and the image and composition method it presents. In this application, the exterior facade of the underground main structure includes every external interface of the underground main structure, including both the interface adjacent to the retaining pile and the top interface.

[0046] See Figure 1 , which is a schematic structural diagram of an embodiment of this application.

[0047] A coping corbel considering the backpressure effect of the retaining structure for an underground structure includes:

[0048] Retaining pile 1;

[0049] Embedded steel bars 3, the lower part of the embedded steel bars 3 is embedded inside the retaining pile 1, and the upper part of the embedded steel bars 3 protrudes from the upper surface of the retaining pile 1;

[0050] Top compression steel plate 4, arranged on the top of the underground main structure 2;

[0051] H-shaped steel corbel 5, a through hole 6 for sleeving the embedded steel bars 3 is opened on the H-shaped steel corbel 5, one end of the H-shaped steel corbel 5 is fixedly connected to the embedded steel bars 3 through the through hole 6, and the other end of the H-shaped steel corbel 5 is fixedly connected to the top compression steel plate 4;

[0052] Closed waterproof layer 7, the closed waterproof layer 7 is arranged on the exterior facade of the underground main structure 2.

[0053] refer to Figure 1 and Figure 2 In this embodiment, the retaining pile 1 can be replaced by any other fixed building structure adjacent to the underground main structure 2, such as a capping beam. Therefore, the meaning of "retaining pile" in this application should not be narrowly interpreted as referring only to the technical term "retaining pile" in the field of construction, but should be broadly interpreted as any fixed building structure adjacent to the underground main structure 2.

[0054] The specific structure of the H-beam steel bracket 5 in the embodiment is shown in the figure. Figure 2 The retaining pile 1 comprises a web 51 and two upper and lower flanges 52. Each flange 52 is divided into two wings by the contact point with the web 51. Through holes 6 are located on the two wings of the upper and lower flanges 52. The structure of the through holes 6 facilitates the installation of embedded reinforcing bars 3, thereby firmly connecting the embedded reinforcing bars 3 and the H-shaped steel bracket 5 into a single unit using a fixed connection method. Effectively, the retaining pile 1, the embedded reinforcing bars 3, and the H-shaped steel bracket 5 form a stable whole. The other end of the H-shaped steel bracket 5 is then fixedly connected to the top pressure plate 4 at the top of the underground main structure 2. This effectively utilizes the self-weight of the retaining pile 1 and the lateral friction resistance of the surrounding soil to achieve the anti-buoyancy and counter-pressure function for the underground main structure 2.

[0055] In addition, the installation of a closed waterproof layer 7 fully considers the integrity of the waterproofing on the outside of the underground main structure 2, ensuring the quality of the one-time integral pouring of concrete 15 for the coping brackets on the top of the enclosure structure and the top of the underground main structure 2, making the force transmission path and stress mode of the underground main structure 2 simple and clear.

[0056] In some embodiments, the fixing connection method can be bolted connection or welding. The exterior facade of the underground main structure 2 may include the contact surface between the underground main structure 2 and the retaining piles 1, or the top surface or any other side of the underground main structure 2. To fully ensure the waterproof performance of the underground main structure 2, the closed waterproof layer 7 can cover any external interface of the underground main structure 2.

[0057] Optionally, it also includes bolts 8, the end of the embedded steel bar 3 is provided with threads, and one end of the H-shaped steel bracket 5 is fixedly connected to the end of the embedded steel bar 3 by bolts 8.

[0058] In this embodiment, the threaded connection is simpler and easier to operate than welding, which helps to shorten the construction period.

[0059] Optionally, it also includes channel steel group 9 and retaining pile top steel plate 10;

[0060] The end of the H-beam steel bracket 5 that connects to the top pressure plate 4 is bent downwards;

[0061] The channel steel group 9 is composed of two C-shaped steels 91 arranged back to back;

[0062] In some embodiments, the embedded reinforcing bar 3 is located in the spaced area between the two C-shaped steel sections 91 of each group of channel steel; specifically, the embedded reinforcing bar 3 can be placed at the symmetrical center of the two C-shaped steel sections 91, and its position on the cross-section is as follows: Figure 4 As shown.

[0063] The retaining pile top steel plate 10 is laid on the top of the retaining pile 1. The upper end of the channel steel group 9 supports the lower end face of one end of the H-shaped steel bracket 5. The lower end of the channel steel group 9 is fixedly connected to the retaining pile top steel plate 10.

[0064] refer to Figure 3 In this embodiment, with Figure 1 The difference in the corresponding embodiment is that a part of the H-beam bracket 5 bends downward, so that the other part of the H-beam bracket 5 is in a higher position relative to this part. This structure with one end higher and the other end lower, compared with the straight H-beam bracket 5, has a larger pouring volume during the later concrete pouring, which further enhances the downward pressure on the underground main structure 2 and has better anti-buoyancy performance.

[0065] In this embodiment, the channel steel group 9 is composed of two C-shaped steels 91 arranged back to back, as shown in the reference. Figure 3 and Figure 4 In each group of channel steel 9, the back sides of the two C-shaped steels 91 are tightly attached to the embedded reinforcing bars 3. In other words, the embedded reinforcing bars 3 are sandwiched in the middle by two C-shaped steels 91 arranged opposite to each other. This symmetrical arrangement is more conducive to the balance and stability of the applied force. Of course, it can be inferred that in some other embodiments, a single C-shaped steel 91 can be used to tightly attach to the embedded reinforcing bars 3, or even C-shaped steels 91 can be omitted, and other strip-shaped or block-shaped supports can be used to fix the embedded reinforcing bars 3.

[0066] Optionally, the channel steel group 9, the H-beam bracket 5, and the retaining pile top steel plate 10 are all fixedly connected by welding.

[0067] Optionally, it also includes a reinforced concrete layer 11 between piles, which is set between the soil between the retaining piles 1 and the closed waterproof layer 7.

[0068] In this embodiment, the reinforced concrete layer 11 between piles is beneficial to both enhancing the overall structural strength and protecting the closed waterproof layer 7.

[0069] Optionally, it also includes an internal stiffening plate 12 for H-beams and an external stiffening plate 13 for H-beams;

[0070] The internal stiffening plate 12 of the H-beam is Z-shaped and is disposed between the upper and lower flanges of the H-beam. The internal stiffening plate 12 of the H-beam is welded to the upper and lower flanges of the H-beam.

[0071] The external stiffening plate 13 of the H-beam is disposed on the lower surface of the lower flange of the H-beam, and both ends of the external stiffening plate 13 of the H-beam are welded to the lower flange of the H-beam.

[0072] refer to Figure 2 , Figure 3 and Figure 5 The Z-shaped H-beam internal stiffening plate 12 enhances the local stability of the web 51 of the H-beam corbel 5; after the concrete 15 is poured, it eliminates the safety hazard of only considering the shear resistance of the corbel concrete and steel reinforcement, and improves the overall strength, stiffness and stability of the counter-pressure corbel joint.

[0073] Optionally, it also includes a water-swellable sealing strip 14;

[0074] The water-swellable waterproof strip 14 is installed at the corner of the closed waterproof layer 7.

[0075] refer to Figure 3 In this embodiment, the water-swellable sealing strip 14 is placed at the corner of the closed waterproof layer 7, which helps to enhance the waterproof performance of the underground main structure 2, ensures the smooth progress of construction, and improves the construction quality to a certain extent.

[0076] Optionally, the embedded steel bars 3 include two rows of embedded steel bars 3 arranged along the axial direction of the retaining pile 1, and the two rows of embedded steel bars 3 are arranged in parallel on both radial sides of the retaining pile 1.

[0077] refer to Figure 3 and Figure 4 Two rows of pre-embedded steel bars 3 are arranged along the axial direction of the retaining pile 1 and are parallel to each other on both radial sides of the retaining pile 1. This helps to clarify the force application and stress path, and better ensures the overall strength and stability of the underground main structure 2. In other embodiments, three, four or more rows may be set as needed or according to construction intentions. The setting of two rows of pre-embedded steel bars 3 in this embodiment is mainly for economic and construction convenience considerations, and should not be construed as the only limitation of this application.

[0078] Optionally, in the two rows of pre-embedded steel bars 3, the number of pre-embedded steel bars 3 in each row is 3.

[0079] refer to Figure 3 and Figure 6 In this embodiment, the number of pre-embedded steel bars 3 in each row is 3, which not only saves construction costs, but also ensures the quality of construction to a certain extent.

[0080] In practical application, the construction can be carried out in the following order according to the specific circumstances: First, the reserved steel bars are reserved during the pouring of the retaining piles or in the capping beam (to meet the anchorage length); then, the concrete surface at the top of the retaining piles or the top of the capping beam is ground smooth, and then the waterproofing of the underground main structure is completed; then, the H-shaped steel bracket is installed in place, and the bolts at the top of the embedded steel bars are tightened; then, the original longitudinal bars and stirrups of the bracket are arranged; finally, the concrete is poured.

[0081] This application's underground structure incorporates a capping bracket designed to withstand the counter-pressure of the retaining structure. The design ensures the waterproofing and integrity of the main underground structure are maintained without compromising subsequent concrete pouring. Furthermore, the force transfer method is simple and clear. The application considers using the self-weight of the reinforced concrete retaining piles and the side friction of the surrounding soil to apply counter-pressure to the top node of the underground structure's outer wall; this technical improvement is extremely crucial and important. This research result is the first of its kind in domestic design and construction technology, possessing significant potential for widespread application and providing a reference for the design and construction of similar projects. Due to its structure, this application possesses the following advantages:

[0082] 1. In the anti-buoyancy design, the main structure and the retaining structure are integrated and the side friction resistance of the retaining structure is considered. This can make full use of the pull-out resistance of the retaining structure, reduce the use of anti-buoyancy measures such as pull-out piles and anti-buoyancy anchors, reduce the project cost, and have obvious economic and social benefits.

[0083] 2. The Z-shaped H-beam internal stiffening plate enhances the local stability of the H-beam corbel web.

[0084] 3. The one-time integral casting of the top of the retaining structure and the top of the main structure with the counterweight bracket eliminates the safety hazards of only considering the shear resistance of the bracket concrete and steel bars, and improves the overall strength, stiffness and stability of the counterweight bracket joint.

[0085] 4. Through the optimization and improvement of conventional counter-pressure corbels, the design and construction of coping corbels for underground structures considering the counter-pressure effect of retaining structures are provided as a reference, and have great prospects for promotion and application.

[0086] Similar parts between the embodiments provided in this application can be referred to mutually. The specific implementation methods provided above are only a few examples under the overall concept of this application and do not constitute a limitation on the scope of protection of this application. For those skilled in the art, any other implementation methods extended from the solution of this application without creative effort shall fall within the scope of protection of this application.

Claims

1. A counterforted coping for a subsurface structure that takes into account the counterpressure of the enclosure, characterized in that, The utility model relates to a kind of underground main body structure, including: Enclosure pile; Pre-buried reinforcing bar, the lower part of the pre-buried reinforcing bar is pre-buried in the inside of the enclosure pile, and the upper part of the pre-buried reinforcing bar is exposed on the upper surface of the enclosure pile; Top compression steel plate, set in the top of underground main body structure; H-shaped steel corbel, the through hole of the H-shaped steel corbel is set to the pre-buried reinforcing bar, one end of the H-shaped steel corbel is fixedly connected with the pre-buried reinforcing bar through the through hole, and the other end of the H-shaped steel corbel is fixedly connected with the top compression steel plate; Closed waterproof layer, set in the outer facade of underground main body structure; Further including bolt, the end of the pre-buried reinforcing bar is provided with thread, and one end of the H-shaped steel corbel is fixedly connected with the end of the pre-buried reinforcing bar through bolt; Further including channel steel group and enclosure pile top steel plate; The end of the H-shaped steel corbel connected with the top compression steel plate is bent downward; The channel steel group is composed of two C-shaped steel back-to-back settings; The enclosure pile top steel plate is laid on the top of the enclosure pile, the upper end of the channel steel group supports the lower end surface of one end of the H-shaped steel corbel, and the lower end of the channel steel group is fixedly connected with the enclosure pile top steel plate; Further including H-shaped steel inner stiffening plate and H-shaped steel outer stiffening plate; The H-shaped steel inner stiffening plate is Z-shaped, arranged between the upper and lower two wing plates of H-shaped steel, and the H-shaped steel inner stiffening plate is welded to the upper and lower two wing plates of H-shaped steel; The H-shaped steel outer stiffening plate is arranged on the lower surface of the lower wing plate of H-shaped steel, and the two ends of the H-shaped steel outer stiffening plate are welded to the lower wing plate of H-shaped steel; Further including water-swelling waterstop; The water-swelling waterstop is arranged at the corner of the closed waterproof layer.

2. A coping bracket for a retaining structure for an underground structure, according to claim 1, wherein The channel steel group, the H-shaped steel corbel and the enclosure pile top steel plate are fixedly connected by welding.

3. The counterforted coping of claim 1, wherein, Further including pile inter-hanging reinforced concrete layer, arranged between soil and the closed waterproof layer between enclosure piles.

4. The counterforted coping of claim 1, wherein, The pre-buried reinforcing bar includes two rows of pre-buried reinforcing bars arranged along the axis of the enclosure pile, and the two rows of pre-buried reinforcing bars are arranged on the radial sides of the enclosure pile.

5. A coping corbel for a below ground structure taking into account the counter pressure of the enclosure according to claim 4, characterized in that, In the two rows of pre-buried reinforcing bars, the number of pre-buried reinforcing bars in each row is 3.

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