Counter-force structure for applying prestress to pit bottom

Abstract

The utility model discloses a counter-force structure for applying prestress to a pit bottom. The counter-force structure comprises a pit bottom pre-stress supporting structure (6), and the pit bottom pre-stress supporting structure comprises a hidden beam (62) and a pit bottom back shore forcing device (63); the pit bottom back shore forcing device is arranged at an assembly interval between the hidden beam and the enclosure structure (1), and the pit bottom back shore forcing device loads back shore force to the bottom of the enclosure structure based on the hidden beam; the pit bottom prestress supporting structure further comprises a foundation strengthening structure, and the foundation strengthening structure is arranged on the side, back on to the enclosure structure, of the hidden beam. The foundation strengthening structure is arranged aiming at the hidden beam, and the hidden beam is back to the foundation strengthening structure, so that larger counter-acting force generated when the pit bottom jacking force application device applies jacking prestress can be borne, the jacking prestress application effect of the pit bottom jacking force application device is strengthened, and strong foundation constant force can be exerted under certain extreme conditions.

Description

Technical Field

[0001] This utility model relates to the field of deep foundation pit construction technology, and in particular to a reaction structure for applying prestress to the bottom of the pit. Background Technology

[0002] Excavation of foundation pits can cause settlement and displacement of the surrounding strata, thereby affecting the safety of nearby subway tunnels and buildings. The main reason for this is that excavation of foundation pits leads to displacement and deformation of the surrounding soil.

[0003] Currently, a prestressed structure and method have been developed, in which, after the construction of the upper and middle prestressed support structure in the pit is completed, the construction of the pit bottom prestressed support structure begins immediately, and this construction process is carried out before the construction of the pit bottom slab; in this way, prestress can be applied to the bottom of the retaining structure at the first time.

[0004] The current problem is:

[0005] In the constructed pit bottom prestressed support structure, the hidden beam has weak structural strength. As the foundation for the pit bottom top support reinforcement device, it cannot withstand the large reaction force generated by the top support force applied by the pit bottom top support reinforcement device under certain extreme conditions, thus limiting the force of the pit bottom top support reinforcement device to apply top support prestress to the retaining structure. Summary of the Invention

[0006] The purpose of this invention is to provide a reaction structure for applying prestress to the bottom of a pit, which can apply strong top-supporting prestress to the bottom of the enclosure structure under extreme conditions.

[0007] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0008] A reaction structure for applying prestress to the bottom of a pit, the reaction structure including a pit bottom prestressing support structure, the pit bottom prestressing support structure including a hidden beam and a pit bottom top support force-adding device; the hidden beam is constructed at the bottom of the pit, along the pit retaining structure, with an assembly gap between the hidden beam and the retaining structure, the pit bottom top support force-adding device is set at the assembly gap between the hidden beam and the retaining structure, the pit bottom top support force-adding device is based on the hidden beam applying a top support force to the bottom of the retaining structure; the pit bottom prestressing support structure also includes a foundation reinforcement structure, the foundation reinforcement structure is set on the side of the hidden beam opposite to the retaining structure.

[0009] Furthermore, the specific implementation of the basic reinforcement structure is a portal frame ring beam structure.

[0010] Furthermore, the specific implementation of the foundation reinforcement structure is as follows: a thickened reinforced pad layer is provided on the side of the hidden beam facing away from the retaining structure. The thickened reinforced pad layer is fixed to the bottom of the foundation pit by a front support steel pipe that is inserted obliquely downward into the bottom of the foundation pit. The upper end of the front support steel pipe is fixedly connected to the part of the thickened reinforced pad layer near the hidden beam, and the lower end of the front support steel pipe is inserted into the soil at the bottom of the foundation pit in an oblique downward direction away from the retaining structure. The thickened reinforced pad layer and the front support steel pipe are combined to form the foundation reinforcement structure.

[0011] Furthermore, the prestressed support structure at the bottom of the pit also includes a reinforced cushion layer, which is disposed on one side of the hidden beam away from the retaining structure, and the foundation reinforcement structure is located between the hidden beam and the reinforced cushion layer.

[0012] Furthermore, a prestressed support member is installed within the assembly interval between the concealed beam and the enclosure structure, the prestressed support member forming a top support for the bottom of the enclosure structure based on the concealed beam.

[0013] Furthermore, a base piece is provided at the assembly interval between the concealed beam and the enclosure structure; the pit bottom support force-adding device can apply a support force to the bottom of the enclosure structure based on the concealed beam and through the base piece; the prestressed support member forms a support to the bottom of the enclosure structure based on the concealed beam and through the base piece.

[0014] Furthermore, the prestressed support member is a prestressed support steel or a prestressed support pier; the prestressed support pier is constructed based on the hidden beam.

[0015] Furthermore, there are some local deep pits at the junction of the reinforced pad layer and the hidden beam, and local steel sections are set in the local deep pits, which provide support to the hidden beam based on the local deep pits.

[0016] Furthermore, the reaction structure includes an upper and middle prestressed support structure within the pit; the upper and middle prestressed support structure within the pit includes a pit top prestressed support structure and a pit middle prestressed support structure; the pit top prestressed support structure includes a pit top horizontal support and a pit top top support force-adding device; an assembly gap is left between the periphery of the pit top horizontal support and the retaining structure; the pit top top support force-adding device is installed at the assembly gap between the pit top horizontal support and the retaining structure, and the pit top top support force-adding device applies a top support force to the retaining structure based on the pit top horizontal support; the pit middle prestressed support structure includes a pit middle horizontal support and a pit middle top support force-adding device; an assembly gap is left between the periphery of the pit middle horizontal support and the retaining structure; the pit middle top support force-adding device is installed at the assembly gap between the pit middle horizontal support and the retaining structure, and the pit middle top support force-adding device applies a top support force to the retaining structure based on the pit middle horizontal support.

[0017] Furthermore, a pit top waler is provided at the top of the retaining structure, and the pit top support force-adding device can apply a support force to the retaining structure based on the pit top horizontal support and through the pit top waler; a pit middle waler is provided at the corresponding pit middle horizontal support position of the retaining structure, and the pit middle support force-adding device can apply a support force to the retaining structure based on the pit middle horizontal support and through the pit middle waler.

[0018] Compared with the prior art, the reaction structure of this utility model has the following advantages:

[0019] A foundation reinforcement structure is set up for the hidden beam. The hidden beam is backed by the foundation reinforcement structure, which enables it to bear a greater reaction force generated by the prestressing applied by the pit bottom support device. This enhances the effect of the prestressing applied by the pit bottom support device and can exert a strong foundation stability under certain extreme conditions. Attached Figure Description

[0020] Figure 1 This is a first schematic diagram of the prestressed structure according to Embodiment 1. Figure 1 This is a side view;

[0021] Figure 2 This is a second schematic diagram of the prestressed structure according to Embodiment 1. Figure 2 This is a top view, showing a localized deep pit at the junction of the reinforced pad and the hidden beam, as well as some of the steel sections within it;

[0022] Figure 3 This is a third schematic diagram of the prestressed structure according to Embodiment 1. Figure 3 This is a top view, showing the prestressed support piers between the continuous wall enclosure structure and the hidden beam;

[0023] Figure 4 This is a first schematic diagram of the prestressed structure according to Embodiment 2. Figure 4 This is a side view;

[0024] Figure 5 This is a second schematic diagram of the prestressed structure according to Embodiment 2. Figure 5 This is a top view;

[0025] Figure 6 This is a third schematic diagram of the prestressed structure in Embodiment 2. Figure 6 This is a top view, showing the prestressed support piers between the continuous wall enclosure structure and the hidden beam;

[0026] Figure 7 This is a schematic diagram of the reaction structure based on Embodiment 3 of this utility model;

[0027] Figure 8 This is a schematic diagram of the reaction structure based on Embodiment 4 of this utility model. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments:

[0029] First, it should be noted that the reaction structure of this utility model for applying prestress to the bottom of a pit is an improvement based on a previously developed prestressing structure and prestressing method. The previously developed prestressing structure and prestressing method will be introduced below through embodiments 1 and 2.

[0030] Implementation method 1:

[0031] See Figures 1 to 3 This embodiment 1 provides a prestressed loading structure, which is used to apply prestress to the retaining structure 1 around the foundation pit in order to prevent displacement and deformation of the retaining structure 1, especially for displacement and deformation at the bottom of the retaining structure pit.

[0032] It should be noted that in this embodiment 1, the retaining structure 1 built around the foundation pit is a continuous wall retaining structure, which is different from the embodiment 2 mentioned later.

[0033] See Figure 1 The prestressed structure of this embodiment 1 mainly consists of three parts: the prestressed support structure 4 at the top of the pit, the prestressed support structure 5 in the middle of the pit, and the prestressed support structure 6 at the bottom of the pit.

[0034] The prestressed support structure 4 at the top of the pit and the prestressed support structure 5 in the middle of the pit can be collectively referred to as the upper and middle prestressed support structure inside the pit.

[0035] The prestressed support structure 4 at the top of the pit is installed at the top of the pit. Specifically, the prestressed support structure 4 includes a horizontal support 41 at the top of the pit and numerous top support and force-increasing devices 43 at the top of the pit.

[0036] A certain gap is left between the periphery of the pit top horizontal support 41 and the pit retaining structure 1. This gap serves as an assembly gap and is reserved space for the installation of the pit top support force-adding device 43.

[0037] It should be noted that the pit top support device 43, as well as the pit middle support device 53 and pit bottom support device 63 mentioned later, are support devices with the same configuration. Those skilled in the art will understand that the support device has a support end that can extend outward based on the device body and output a support force.

[0038] The numerous pit top support reinforcement devices 43 mentioned earlier are all installed at the assembly interval between the pit top horizontal support 41 and the retaining structure 1, and these pit top support reinforcement devices 43 are arranged regularly and discretely along the periphery of the pit top horizontal support 41.

[0039] For each pit top support reinforcement device 43, the device body of the pit top support reinforcement device 43 is fixedly installed based on the periphery of the pit top horizontal support 41, and the top support end of the pit top support reinforcement device 43 is assembled and connected to the top of the enclosure structure 1.

[0040] In this way, the top support device 43 can apply a top support force to the top of the retaining structure 1 based on the periphery of the horizontal support 41 at the top of the pit, so as to counteract the "impact of the displacement and deformation of the soil around the pit on the top of the retaining structure 1".

[0041] It should be noted that, in this embodiment, the pit top horizontal support 41 is provided with a pit top support waler 42, which is located around the periphery of the pit top horizontal support 41. In this way, the device body of the pit top support force application device 43 is fixedly installed based on the pit top support waler 42.

[0042] In addition, it should be noted that a waler is also provided on the top of the enclosure structure 1, which is referred to as the pit top waler 31.

[0043] In this embodiment 1, the top support force-adding device is essentially a hydraulic telescopic cylinder. The telescopic end (commonly known as the "cylinder head") of the hydraulic telescopic cylinder is equivalent to the top support end of the top support force-adding device, and the cylinder body of the hydraulic telescopic cylinder is equivalent to the device body of the top support force-adding device.

[0044] The previously mentioned "the main body of the pit top support reinforcement device 43 is fixedly installed based on the periphery of the pit top horizontal support 41, and the top support end of the pit top support reinforcement device 43 is assembled and connected to the top of the retaining structure 1"

[0045] Specifically, it is

[0046] "The cylinder body of the hydraulic telescopic cylinder is fixedly installed based on the pit top support waler 42 around the pit top horizontal support 41, and the telescopic end of the hydraulic telescopic cylinder is assembled and connected to the pit top waler 31 at the top of the retaining structure 1."

[0047] The prestressed support structure 5 in the pit is located in a position that is neither at the top nor the bottom inside the pit. Specifically, the prestressed support structure 5 in the pit includes a horizontal support 51 in the pit and a number of top support and force-increasing devices 53 in the pit.

[0048] A certain gap is left between the periphery of the horizontal support 51 in the pit and the pit retaining structure 1. This gap serves as an assembly gap to reserve space for the installation of the pit top support reinforcement device 53. The numerous pit top support reinforcement devices 53 mentioned above are all installed at the assembly gap between the horizontal support 51 in the pit and the retaining structure 1, and these pit top support reinforcement devices 53 are arranged regularly and discretely along the periphery of the horizontal support 51 in the pit.

[0049] For each pit-supporting device 53, the device body of the pit-supporting device 53 is fixedly installed based on the periphery of the pit-horizontal support 51, and the top support end of the pit-supporting device 53 is assembled and connected to the middle of the enclosure structure 1.

[0050] In this way, the top support device 53 in the pit can apply a top support force to the middle part of the retaining structure 1 based on the periphery of the horizontal support 51 in the pit, so as to counteract the "impact of the displacement and deformation of the soil around the pit on the middle part of the retaining structure 1".

[0051] It should be noted that the "middle part of retaining structure 1" mentioned here refers to "the part of retaining structure 1 located at the middle of the depth direction of the foundation pit".

[0052] It should be noted that, in this embodiment, the horizontal support 51 in the pit is provided with a pit support waler 52, which is located around the periphery of the horizontal support 51. In this way, the main body of the pit top support force-adding device 53 is fixedly installed based on the pit support waler 52.

[0053] As mentioned above, in this embodiment, the top support force-adding device is a hydraulic telescopic cylinder. In this way, the device body of the pit top support force-adding device 53 mentioned earlier is fixedly installed based on the periphery of the pit horizontal support 51, and the top support end of the pit top support force-adding device 53 is assembled and connected to the middle of the retaining structure 1.

[0054] Specifically,

[0055] "The cylinder body of the hydraulic telescopic cylinder is fixedly installed based on the pit support waler 52 around the pit horizontal support 51, and the telescopic end of the hydraulic telescopic cylinder is assembled and connected to the middle of the enclosure structure 1."

[0056] It should be noted that the prestressed support structure 4 at the top of the pit and the prestressed support structure 5 in the middle of the pit mentioned above can be collectively referred to as the upper and middle prestressed support structure in the pit.

[0057] It should be noted that the term "prestressed support structure in the middle and upper part of the pit" is a general term for "prestressed support structures set in all parts of the pit except the bottom".

[0058] The most important innovation of the prestressed structure in this embodiment 1 is the setting of the prestressed support structure 6 at the bottom of the pit.

[0059] Specifically, the prestressed support structure 6 at the bottom of the pit mainly includes a reinforced pad layer 61, a hidden beam 62, and numerous pit bottom top support devices 63.

[0060] The hidden beam 62 is constructed at the bottom of the foundation pit. The hidden beam 62 is constructed along the trend of the foundation pit retaining structure 1. Furthermore, a certain gap is left between the hidden beam 62 and the foundation pit retaining structure 1 as an assembly gap. This assembly gap is reserved space for the installation of the pit bottom top support force-adding device 63.

[0061] The numerous pit bottom support reinforcement devices 63 mentioned earlier are all installed at the assembly interval between the hidden beam 62 and the retaining structure 1, and these pit bottom support reinforcement devices 63 are arranged regularly and discretely along the hidden beam 62 (or, along the perimeter of the pit).

[0062] For each pit bottom support reinforcement device 63, the device body of the pit bottom support reinforcement device 63 is fixedly installed based on the hidden beam 62, and the top support end of the pit bottom support reinforcement device 63 is assembled and connected to the bottom of the enclosure structure 1.

[0063] In this way, the bottom support device 63 can apply a top support force to the bottom of the retaining structure 1 based on the hidden beam 62, so as to counteract the "impact of the displacement and deformation of the soil around the foundation pit on the bottom of the retaining structure 1". It should be noted that the "bottom of the retaining structure 1" mentioned in this article refers to "the part of the retaining structure 1 located at the bottom of the foundation pit".

[0064] The reinforced cushion layer 61 is set on the side of the hidden beam 62 at the bottom of the foundation pit, away from the retaining structure 1. The thickness of the reinforced cushion layer 61 is in the range of 150 to 500 mm, and the reinforcement is determined according to the thickness. The diameter of the reinforcement is in the range of 6 to 25 mm.

[0065] It should be noted that the reinforced cushion layer 61 is constructed based on the pre-constructed engineering piles 7 at the bottom of the foundation pit. The reinforced cushion layer 61 is rigidly connected to the engineering piles 7, and the horizontal force is provided by the friction between the engineering piles 7, the reinforced cushion layer 61 and the soil.

[0066] Furthermore, at the junction of the reinforced pad 61 and the hidden beam 62, the reinforced pad 61 is fixedly connected to the hidden beam 62 by a steel reinforcement structure, forming a whole.

[0067] It should be noted that in other embodiments, the reinforced cushion layer 61 and the engineering pile 7 may not be connected by a connection structure, and the horizontal force may be provided solely by the friction between the reinforced cushion layer and the soil.

[0068] A preferred solution:

[0069] See Figure 2 When encountering a situation where there are some local deep pits 65 at the junction of the reinforced pad 61 and the hidden beam 62, several local steel sections 66 can be set in each local deep pit 65. These local steel sections 66 provide support to the hidden beam 62 based on the local deep pit 65.

[0070] It should be noted that the aforementioned localized deep pit 65 is mainly used as an elevator shaft, sump pit, or for other purposes. These locations may be exactly on or close to the edge of the foundation pit. Due to the presence of the localized deep pit, the original top support reinforcement device's force transmission is not continuous, i.e., a disconnection occurs in the pit. Therefore, it is necessary to insert a section of steel into the pit, with one end in contact with the top support reinforcement device to transmit force, and the other end supporting the side of the deep pit to achieve the purpose of force transmission.

[0071] It should be noted that the number of local steel sections 66 set in the local deep pit 65 can be determined according to actual needs.

[0072] Numerous steel sections are installed within the assembly interval between the hidden beam 62 and the enclosure structure 1 as prestressed support steel sections (not shown in the figure, but can be referenced). Figure 3 (67) Prestressed bearing support piers in the middle.

[0073] These prestressed support steel sections are arranged regularly and discretely along the direction of the hidden beam 62 within the assembly interval, and these prestressed support steel sections are arranged at intervals with the numerous pit bottom support reinforcement devices 63 mentioned above.

[0074] These prestressed supporting steel sections form a top-supporting posture on the bottom of the retaining structure 1 based on the hidden beam 62, which creates conditions for removing the pit bottom top-supporting device 63 (detailed explanation below).

[0075] A preferred alternative to prestressed bearing steel:

[0076] See Figure 3 Numerous supports are provided based on the concealed beam 62. These supports, serving as prestressed bearing supports 67, are installed within the assembly interval between the concealed beam 62 and the retaining structure 1. These prestressed bearing supports 67 are arranged regularly and discretely along the direction of the concealed beam 62 within the assembly interval. These prestressed bearing supports 67 perform the same function as the previously mentioned prestressed bearing steel sections, providing support to the bottom of the retaining structure 1 based on the concealed beam 62.

[0077] The prestressed bearing support 67 is a reinforced concrete structure, which is cast integrally with the hidden beam 62. The prestressed bearing support 67 can also be a steel structure, which can be connected to the hidden beam 62 integrally by pre-embedding or pre-embedding welding.

[0078] The prestressed supporting steel and the prestressed supporting pier 67 can be collectively referred to as "prestressed supporting components". In other embodiments, other types of components can be used as prestressed supporting components to replace the prestressed supporting steel or the prestressed supporting pier 67 to achieve their functions.

[0079] It should be noted that when installing the top support reinforcement device 43, the middle support reinforcement device 53, and the bottom support reinforcement device 63, the installation position of the support reinforcement device should correspond to the wall joint of the continuous wall retaining structure. Since the wall joint is a weak point of the continuous wall retaining structure, this installation method is beneficial to the stable support of the continuous wall retaining structure.

[0080] This embodiment 1 also provides a method for applying prestress to the retaining wall within the foundation pit, which specifically includes steps S1 to S3.

[0081] S1, construct the prestressed support structure in the middle and upper part of the pit.

[0082] Step S1 specifically includes steps S11 to S12.

[0083] S11, Construct the prestressed support structure 4 for the pit top.

[0084] Specifically, this includes steps S111 to S114.

[0085] S111, excavation work (i.e., excavating the soil) is carried out at the location of the foundation pit project until the current depth of the foundation pit reaches the design position of the prestressed support structure 4 at the top of the pit.

[0086] S112, construct a horizontal support 41 at the design location (top of the pit) of the prestressed support structure 4 at the pit top.

[0087] An assembly gap is left between the periphery of the constructed pit top horizontal support 41 and the retaining structure 1, thereby reserving space for the subsequent installation of the pit top support force-adding device 43.

[0088] Preferably, while constructing the pit top horizontal support 41, a pit top support waler 42 can be constructed around the pit top horizontal support 41, thereby establishing a good installation foundation for the subsequent installation of the pit top support force-adding device 43.

[0089] S113, a number of pre-prepared top support devices are installed as pit top support devices 43 at the assembly interval between the pit top horizontal support 41 and the retaining structure 1, and these pit top support devices 43 are arranged regularly and discretely along the periphery of the pit top horizontal support 41.

[0090] For each pit top support reinforcement device 43, the device body of the pit top support reinforcement device 43 is fixedly installed based on the periphery of the pit top horizontal support 41, and the top support end of the pit top support reinforcement device 43 is assembled and connected to the top of the enclosure structure 1.

[0091] Preferably, if in step S112, while constructing the pit top horizontal support 41, a pit top support waler 42 is constructed around the pit top horizontal support 41, then the device body of the pit top support force-adding device 43 is fixedly installed based on the pit top support waler 42.

[0092] S114. Existing detection methods are used to detect the deformation status (deformation data) of the top of the retaining structure 1. Based on the deformation status of the top of the retaining structure 1 and in accordance with the design standards, the pit top support force application device 43 is controlled to apply an appropriate support force (prestress) to the top of the retaining structure 1 so that the deformation status of the top of the retaining structure 1 meets the design standards.

[0093] S12, construct the prestressed support structure 5 in the pit.

[0094] Specifically, this includes steps S121 to S124.

[0095] S121, excavation work (i.e., excavating the soil) is carried out in the current foundation pit until the depth of the current foundation pit reaches the design position of the prestressed support structure 5 in the pit.

[0096] S122, construct a horizontal support 51 in the pit at the designed location of the prestressed support structure 5 in the pit.

[0097] An assembly gap is left between the periphery of the constructed pit horizontal support 51 and the retaining structure 1, thus reserving space for the subsequent installation of the pit top support force-adding device 53.

[0098] Preferably, while constructing the horizontal support 51 in the pit, a pit support waler 52 can be constructed around the horizontal support 51 in the pit, thereby establishing a good installation foundation for the subsequent installation of the pit top support force-adding device 53.

[0099] S123, a number of pre-prepared top support devices are installed as pit top support devices 53 at the assembly interval between the pit horizontal support 51 and the retaining structure 1, and these pit top support devices 53 are arranged regularly and discretely along the periphery of the pit horizontal support 51.

[0100] For each pit-supporting device 53, the device body of the pit-supporting device 53 is fixedly installed based on the periphery of the pit-horizontal support 51, and the top support end of the pit-supporting device 53 is assembled and connected to the middle of the enclosure structure 1.

[0101] Preferably, if in step S122, while constructing the horizontal support 51 in the pit, a pit support waler 52 is constructed around the horizontal support 51 in the pit, then the device body of the pit top support force-adding device 53 is fixedly installed based on the pit support waler 52.

[0102] S124. Existing detection methods are used to detect the deformation status (deformation data) of the middle part of the retaining structure 1. Based on the deformation status of the middle part of the retaining structure 1 and in accordance with the design standards, the top support force 53 in the pit is controlled to apply an appropriate top support force (prestress) to the middle part of the retaining structure 1 so that the deformation status of the middle part of the retaining structure 1 meets the design standards.

[0103] S2, after the construction of the upper and middle prestressed support structure in the pit is completed in step S1, the construction of the pit bottom prestressed support structure 6 shall begin immediately. This construction process shall be carried out before the construction of the bottom plate. Then, the pit bottom prestressed support structure 6 shall be used to apply top support prestress to the bottom of the retaining structure 1.

[0104] In this way, the bottom of the retaining structure 1 can be supported and the top prestress can be applied in the first place, thereby avoiding the situation that "the bottom of the retaining structure 1 will be displaced and deformed before the bottom plate is completed", thus ensuring the construction quality of the entire foundation pit project.

[0105] This step S2 specifically includes steps S21 to S27.

[0106] S21, carry out excavation work (i.e., excavate the soil) in the current foundation pit until the depth of the current foundation pit reaches the design depth of the foundation pit project.

[0107] S22, at the bottom of the current foundation pit, a hidden beam 62 is constructed along the retaining structure 1, and a certain interval is reserved between the constructed hidden beam 62 and the retaining structure 1 as an assembly interval.

[0108] Preferred solution:

[0109] While constructing the concealed beam 62, prestressed support piers 67 can be built based on the concealed beam 62. These prestressed support piers 67 are set within the assembly interval between the concealed beam 62 and the retaining structure 1, and are arranged regularly and discretely along the direction of the concealed beam 62 within the assembly interval. The prestressed support piers 67 are reinforced concrete structures, cast integrally with the concealed beam 62. These prestressed support piers 67 provide support to the bottom of the retaining structure 1 based on the concealed beam 62.

[0110] S23, at the bottom of the current foundation pit, on the side of the hidden beam 62 facing away from the retaining structure 1, a reinforced cushion layer 61 is constructed based on the "engineering pile 7 pre-constructed at the bottom of the current foundation pit".

[0111] The thickness of the reinforced cushion layer 61 is in the range of 150 to 500 mm, and the reinforcement is determined according to the thickness, with the reinforcement diameter in the range of 6 to 25 mm.

[0112] Preferred solution:

[0113] When encountering situations where there are some local deep pits at the junction of the reinforced pad and the hidden beam, local steel sections are installed in the local deep pits, and the local steel sections provide support to the hidden beam based on the local deep pits.

[0114] For each local deep pit 65, two local steel sections 66 are set inside the local deep pit 65. These two local steel sections 66 provide support for the hidden beam 62 based on the local deep pit 65.

[0115] S24, a number of pre-prepared hydraulic telescopic cylinders are assembled as pit bottom support force-adding devices 63 in the assembly interval between the hidden beam 62 and the enclosure structure 1. These pit bottom support force-adding devices 63 are arranged regularly and discretely along the hidden beam 62.

[0116] For each pit bottom support force-adding device 63, the device body of the pit bottom support force-adding device 63 is fixedly installed based on the hidden beam 62, and the top support end of the pit bottom support force-adding device 63 is assembled and connected to the bottom of the retaining structure 1. In this way, the pit bottom support force-adding device 63 can apply a support force to the bottom of the retaining structure 1 based on the hidden beam 62.

[0117] After the installation of the pit bottom support force-adding device 63 is completed, the pit bottom support force-adding device 63 can be pre-controlled to apply appropriate support prestress to the bottom of the retaining structure 1.

[0118] S25. Existing detection methods are used to detect the deformation status (deformation data) at the bottom of the retaining structure 1. Based on the deformation status at the bottom of the retaining structure 1 and in accordance with the design standards, the pit bottom support force-adding device 63 is controlled to apply appropriate support prestress to the bottom of the retaining structure 1 so that the deformation status at the bottom of the retaining structure 1 meets the design standards.

[0119] S26, a number of pre-prepared steel sections are placed as prestressed supporting steel sections in the assembly interval between the hidden beam 62 and the enclosure structure 1 (not shown in the figure).

[0120] These prestressed supporting steel sections are arranged regularly and discretely along the direction of the hidden beam 62 within the assembly interval. These prestressed supporting steel sections are arranged at intervals with the numerous pit bottom support reinforcement devices 63 mentioned above. For each prestressed supporting steel section, the prestressed supporting steel section is close to the retaining structure 1. The joint between the prestressed supporting steel section and the hidden beam 62 is filled with pre-prepared grout. After the grout at the joint has cured to a suitable strength, the prestressed supporting steel section can form a support for the bottom of the retaining structure 1 based on the hidden beam 62. Then all the pit bottom support reinforcement devices 63 can be removed.

[0121] Preferred solution:

[0122] If, as described in the preferred embodiment of step S22, "while constructing the hidden beam 62, some prestressed support piers 67 can be constructed based on the hidden beam 62," then there is no need to install prestressed support steel. Instead, pre-prepared grouting material is poured and filled into the joint between the prestressed support piers 67 and the retaining structure 1. After the grouting material at the joint has cured to a suitable strength, the prestressed support piers 67 can form a top support for the bottom of the retaining structure 1 based on the hidden beam 62. Then, all the pit bottom support reinforcement devices 63 can be removed. In other words, the function of the prestressed support steel is achieved by the prestressed support piers 67.

[0123] In other embodiments, wedge-shaped steel can be used to fill the joint between the prestressed support pier 67 and the retaining structure 1 instead of grouting material.

[0124] It should be noted that the prestressed supporting steel and the prestressed supporting pier 67 can be collectively referred to as "prestressed supporting components". In other embodiments, other types of components can be used as prestressed supporting components to replace the prestressed supporting steel or the prestressed supporting pier 67 to achieve their functions.

[0125] S27, pour the prepared casting material into the assembly gap between the hidden beam 62 and the enclosure structure 1 to form a permanent support for the bottom of the enclosure structure 1.

[0126] S3. After the permanent support for the bottom of the enclosure structure 1 is completed, the pit bottom plate can be constructed according to the schedule. During this process, there is no need to worry about the bottom of the enclosure structure 1 deforming.

[0127] It should be noted that the reinforced pad layer 61 can be broadly categorized as a pad layer, which can also be implemented using steel plates. The thickness of the steel plate is 5-30mm. The steel plates can be connected by welding or bolts; the connection or disconnection between the steel plate and the engineering pile 7 is selected according to the magnitude of the required reaction force. The steel plate can be replaced by a composite steel structure, and the connection or disconnection between the composite steel structure and the engineering pile 7 is selected according to the magnitude of the required reaction force.

[0128] If the number of engineering piles 7 is insufficient, temporary piles or structures can be used to supplement them.

[0129] It should be noted that the hidden beam 62 can be a steel beam or a concrete beam. The steel beam is a structural steel section or a composite steel structure.

[0130] The advantages of the prestressed structure and method of this embodiment 1 are:

[0131] In the prestressed structure and method of this embodiment, after the construction of the upper and middle prestressed support structure in the pit is completed, the construction of the pit bottom prestressed support structure 6 is started immediately. This construction process is carried out before the construction of the pit bottom slab. In this way, prestress can be applied to the bottom of the retaining structure 1 at the first time, so as to take measures to deal with the displacement deformation of the bottom of the retaining structure 1 as soon as possible, thereby solving all the technical problems mentioned in the background art.

[0132] Implementation Method 2:

[0133] See Figures 4 to 6 This embodiment 2 provides a prestressed structure. Compared with the prestressed structure provided in embodiment 1, the overall concept of the two is basically the same. The main difference is that the foundation pit retaining structure 1 involved in this embodiment is a pile retaining structure, such as bored cast-in-place pile piles, steel pile piles, precast pile piles, etc.

[0134] For this pile retaining structure, the prestressed structure in Embodiment 2 is specifically modified from Embodiment 1 to adapt to the pile retaining structure. In other words, this embodiment mainly addresses how to apply the concept of Embodiment 1 to the pile retaining structure.

[0135] Specifically, the main changes are as follows:

[0136] Regarding the changes to the prestressed support structure 5 in the pit:

[0137] A waler is provided at the position of the horizontal support 51 in the pit in the middle of the retaining structure 1. This waler is called the pit waler 32.

[0138] The top support end of the pit top support force-adding device 53 is assembled and connected to the pit waler 32, or in other words, the top support end of the pit top support force-adding device 53 is assembled and connected to the middle part of the retaining structure 1 through the pit waler 32. In this way, the pit top support force-adding device 53 can apply a top support force to the middle part of the retaining structure 1 based on the periphery of the pit horizontal support 51 and through the pit waler 32.

[0139] Regarding the changes to the prestressed support structure 6 at the bottom of the pit:

[0140] A long I-beam is provided as a base piece 68 at the assembly interval between the hidden beam 62 and the enclosure structure 1. The base piece 68 is fixedly connected to the bottom of the enclosure structure 1 by means of adhesive bonding.

[0141] The top support end of the pit bottom support force-adding device 63 is assembled and connected to the bottom pad 68, or in other words, the top support end of the pit bottom support force-adding device 63 is assembled and connected to the bottom of the enclosure structure 1 through the bottom pad 68. In this way, the pit bottom support force-adding device 63 can apply a top support force to the bottom of the enclosure structure 1 based on the hidden beam 62 and through the bottom pad 68.

[0142] The prestressed support component (prestressed support pier 67 or prestressed support steel) mentioned earlier also forms a top support for the bottom of the enclosure structure 1 through the pad component 68.

[0143] In this embodiment 2, the base member 68 is an I-beam, while in other embodiments, other suitable components can also be used as the base member 68.

[0144] This embodiment 2 also provides a method for applying prestress.

[0145] The prestressing method of this embodiment 2 is basically the same as the prestressing method provided in embodiment 1. The main difference is that the corresponding changes are made for the changes in the prestressing structure.

[0146] Specifically, the main changes are as follows:

[0147] Changes to step S122:

[0148] While constructing the horizontal support 51 in the pit, a pit waler 32 is constructed at the position corresponding to the horizontal support 51 in the pit in the middle of the retaining structure 1. An assembly gap is left between the periphery of the constructed horizontal support 51 in the pit and the pit waler 32 constructed on the retaining structure 1, thereby reserving space for the subsequent installation of the pit top support force-adding device 53.

[0149] Changes to step S123:

[0150] The top support end of the pit top support force-increasing device 53 is assembled and connected to the pit waler 32, or in other words, the top support end of the pit top support force-increasing device 53 is assembled and connected to the middle part of the enclosure structure 1 through the pit waler 32.

[0151] Changes to step S22:

[0152] After the hidden beam 62 is constructed, a long I-beam is set as a base piece 68 at the assembly interval between the hidden beam 62 and the enclosure structure 1. The base piece 68 is fixedly connected to the bottom of the enclosure structure 1 by means of mortar bonding.

[0153] Changes to step S24:

[0154] The top support end of the pit bottom support reinforcement device 63 is assembled and connected to the bottom pad 68, or in other words, the top support end of the pit bottom support reinforcement device 63 is assembled and connected to the bottom of the enclosure structure 1 through the bottom pad 68.

[0155] Changes to step S26:

[0156] The prestressed supporting steel is attached to the bottom pad 68 of the enclosure structure 1. The prestressed supporting steel can support the bottom of the enclosure structure 1 based on the hidden beam 62 and through the bottom pad 68.

[0157] The changes in Embodiment 2 compared to Embodiment 1 are roughly as described above.

[0158] It should be noted that the reason for adding the pit waler 32 and the bottom pad 68 is that the pile retaining structure is composed of a large number of piles arranged together. Since there is no connection between the piles, it is impossible to support the entire pile retaining structure by supporting a certain point. However, the pit waler 32 and the bottom pad 68 can connect the large number of piles together, so that the entire pile retaining structure can be supported by supporting a certain point.

[0159] The following embodiments 3 and 4 illustrate in detail the reaction structure of this utility model applied to the bottom of a pit for applying prestress.

[0160] Implementation Method 3:

[0161] This embodiment 3 provides a reaction structure, which is an improvement on the prestressed loading structure provided in embodiments 1 and 2.

[0162] See Figure 7 The improvement of the reaction structure in Embodiment 3 compared to Embodiments 1 and 2 is as follows:

[0163] The prestressed support structure 6 at the bottom of the pit is also provided with a base composite ring beam 613, which is mainly designed for the hidden beam 62.

[0164] It should be noted that the base composite ring beam 613 is composed of two ring beams connected together by numerous connecting beams.

[0165] The base composite ring beam 613 is located on the side of the concealed beam 62 facing away from the retaining structure 1, and between the concealed beam 62 and the reinforced cushion layer 61. The base composite ring beam 613 is fixed to the bottom of the foundation pit by two rows of numerous engineering piles 616. The two rows of engineering piles 616 and the base composite ring beam 613 together form a portal frame ring beam structure. The concealed beam 62, the base composite ring beam 613, and the reinforced cushion layer 61 are tightly connected together.

[0166] In this way, the hidden beam 62 is backed by the base composite ring beam 613, and the hidden beam 62 can bear a greater reaction force generated by the prestressing applied by the pit bottom support device 63, thereby enhancing the effect of the prestressing applied by the pit bottom support device 63.

[0167] Implementation Method 4:

[0168] This embodiment 4 provides a reaction structure, which is an improvement on the prestressed loading structure provided in embodiments 1 and 2.

[0169] See Figure 8 The improvement of the reaction structure in Embodiment 4 compared to Embodiments 1 and 2 is as follows:

[0170] The prestressed support structure 6 at the bottom of the pit is also provided with a thickened reinforced pad 617, which is mainly designed for the hidden beam 62.

[0171] The thickened reinforced pad 617 is set on the side of the hidden beam 62 facing away from the enclosure structure 1, and is located between the hidden beam 62 and the reinforced pad 61. The hidden beam 62, the thickened reinforced pad 617 and the reinforced pad 61 are close together.

[0172] The thickened reinforced cushion layer 617 is fixed to the bottom of the foundation pit by a number of downwardly inclined front support steel pipes 618. The upper end of the front support steel pipe 618 is fixedly connected to the part of the thickened reinforced cushion layer 617 near the hidden beam 62, and the lower end of the front support steel pipe 618 is inserted into the soil at the bottom of the foundation pit in a downwardly inclined direction away from the retaining structure 1.

[0173] In this way, the hidden beam 62 is backed by the thickened reinforced pad layer 617, and the hidden beam 62 can bear a greater reaction force generated by the prestressing applied by the pit bottom support device 63, thereby enhancing the effect of the prestressing applied by the pit bottom support device 63.

[0174] Based on the above embodiments 3 and 4, the main concept of the present invention can be summarized as follows:

[0175] A foundation reinforcement structure is provided on the side of the hidden beam 62 facing away from the enclosure structure 1. With the hidden beam 62 backing against the foundation reinforcement structure, the hidden beam 62 can bear a greater reaction force generated by the prestressing applied by the pit bottom support device 63, thereby enhancing the effect of the prestressing applied by the pit bottom support device 63.

[0176] In implementation method 3, the specific form of the foundation reinforcement structure is a portal frame ring beam structure consisting of a base composite ring beam 613 and two rows of engineering piles 616.

[0177] In embodiment 4, the specific form of the basic reinforcement structure is the combination of the thickened reinforced pad layer 617 and the front support steel pipe 618.

[0178] The above are merely preferred embodiments of the present utility model and are not intended to limit the scope of protection of the present utility model. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the scope of protection of the present utility model.

Claims

1. A reaction structure for applying prestress to the bottom of a pit, characterized in that: The reaction structure includes a pit bottom prestressed support structure (6), which includes a hidden beam (62) and a pit bottom top support force-adding device (63). The hidden beam (62) is constructed at the bottom of the foundation pit. The hidden beam (62) runs along the foundation pit retaining structure (1). There is an assembly gap between the hidden beam (62) and the retaining structure (1). The pit bottom top support force-adding device (63) is set at the assembly gap between the hidden beam (62) and the retaining structure (1). The pit bottom top support force-adding device (63) applies a top support force to the bottom of the retaining structure (1) based on the hidden beam (62). The pit bottom prestressed support structure (6) also includes a foundation reinforcement structure, which is set on one side of the hidden beam (62) opposite to the enclosure structure (1).

2. The reaction structure for applying prestress to the bottom of a pit according to claim 1, characterized in that: The specific implementation of the basic reinforcement structure is a portal frame ring beam structure.

3. The reaction structure for applying prestress to the bottom of a pit according to claim 1, characterized in that: The specific implementation of the basic reinforcement structure is as follows: A thickened reinforced pad layer (617) is provided on one side of the hidden beam (62) facing away from the retaining structure (1). The thickened reinforced pad layer (617) is fixed to the bottom of the foundation pit by a front support steel pipe (618) that is inserted downwards at the bottom of the foundation pit. The upper end of the front support steel pipe (618) is fixedly connected to the part of the thickened reinforced pad layer (617) near the hidden beam (62). The lower end of the front support steel pipe (618) is inserted into the soil at the bottom of the foundation pit in a downward direction away from the retaining structure (1). The thickened reinforced pad layer (617) and the front support steel pipe (618) are combined to form the foundation reinforcement structure.

4. The reaction structure for applying prestress to the bottom of a pit according to claim 1, characterized in that: The prestressed support structure (6) at the bottom of the pit also includes a reinforced cushion layer (61), which is located on one side of the hidden beam (62) away from the enclosure structure (1), and the foundation reinforcement structure is located between the hidden beam (62) and the reinforced cushion layer (61).

5. The reaction structure for applying prestress to the bottom of a pit according to claim 1, characterized in that: A prestressed support is provided in the assembly interval between the hidden beam (62) and the enclosure structure (1), the prestressed support forming a top support on the bottom of the enclosure structure (1) based on the hidden beam (62).

6. The reaction structure for applying prestress to the bottom of a pit according to claim 5, characterized in that: A pad (68) is provided at the assembly interval between the hidden beam (62) and the enclosure structure (1); The pit bottom support force-adding device (63) can apply a support force to the bottom of the enclosure structure (1) based on the hidden beam (62) and through the padding component (68); The prestressed support member is based on the hidden beam (62) and forms a top support on the bottom of the enclosure structure (1) through the pad member (68).

7. The reaction structure for applying prestress to the bottom of a pit according to claim 5, characterized in that: The prestressed support component is a prestressed support steel or a prestressed support pier (67); The prestressed support pier (67) is constructed based on the hidden beam (62).

8. The reaction structure for applying prestress to the bottom of a pit according to claim 1, characterized in that: At the junction of the reinforced pad layer (61) and the hidden beam (62), there are some local deep pits (65), and local steel sections (66) are provided in the local deep pits (65), which form a top support for the hidden beam (62) based on the local deep pits (65).

9. The reaction structure for applying prestress to the bottom of a pit according to claim 1, characterized in that: The reaction structure includes a prestressed support structure in the upper part of the pit; The prestressed support structure in the pit includes a prestressed support structure at the top of the pit (4) and a prestressed support structure in the middle of the pit (5); The prestressed support structure (4) at the top of the pit includes a horizontal support (41) at the top of the pit and a top support force-increasing device (43) at the top of the pit; An assembly gap is left between the periphery of the pit top horizontal support (41) and the enclosure structure (1); The pit top support force-adding device (43) is installed at the assembly interval between the pit top horizontal support (41) and the retaining structure (1). The pit top support force-adding device (43) applies a support force to the retaining structure (1) based on the pit top horizontal support (41). The prestressed support structure (5) in the pit includes a horizontal support (51) in the pit and a top support force-adding device (53) in the pit; An assembly gap is left between the periphery of the horizontal support (51) in the pit and the enclosure structure (1); The pit top support force-adding device (53) is installed at the assembly interval between the pit horizontal support (51) and the retaining structure (1). The pit top support force-adding device (53) applies a top support force to the retaining structure (1) based on the pit horizontal support (51).

10. The reaction structure for applying prestress to the bottom of a pit according to claim 1, characterized in that: A pit top waler (31) is provided on the top of the enclosure structure (1). The pit top support force-adding device (43) can apply a top support force to the enclosure structure (1) based on the pit top horizontal support (41) and through the pit top waler (31). A pit waler (32) is provided at the position of the horizontal support (51) in the corresponding pit of the enclosure structure (1). The pit top support force-adding device (53) can apply a top support force to the enclosure structure (1) based on the pit horizontal support (51) and through the pit waler (32).

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