Support system for foundation pit and construction method thereof

Abstract

The application provides a supporting system of a foundation pit and a construction method thereof. The supporting system of the foundation pit comprises a first supporting system, a second supporting system,..., an n-th supporting system distributed from top to bottom, and a steel support, wherein n is an integer greater than or equal to 3; the steel support is detachably installed on a first region of a last partition of an n-th layer where earthwork excavation is completed. By installing a temporary steel support at the end of a concrete supporting system construction, the exposed time of the foundation pit without support is reduced, thereby effectively reducing the time-space effect of the earth wall in the process of forming the first supporting system, and effectively controlling the deformation of the foundation pit. In addition, since the steel support and the concrete support can both adopt a servo system, the deformation of the foundation pit can be actively controlled, and the micro-deformation control of the foundation pit is more beneficially ensured.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a support system for foundation pits and its construction method. Background Technology

[0002] In foundation pit engineering, concrete supports are characterized by high rigidity but require long on-site pouring and curing times; steel supports, on the other hand, are characterized by low rigidity, easy installation and dismantling, fast construction speed, and reusability. Servo systems are used in both steel and concrete supports during on-site construction. However, the limited load-bearing capacity and low rigidity of steel supports limit their use in large, deep foundation pits. Concrete supports, due to their long construction and curing times, are prone to deformation under strict deformation control requirements, especially when soil exposure prevents timely support formation. Considering that it typically takes 3 days from excavation completion to support formation, plus another 3 days for concrete strength development and servo system application, the soil exposure time before timely support formation is approximately 6-7 days. The deformation of a single support exposed for 6-7 days is around 20mm, with the greater the excavation depth, the greater the spatial and temporal effect. In deep foundation pits with multiple supports, the accumulated deformation from unsupported soil exposure, combined with deformation during excavation, may exceed environmental allowable limits.

[0003] Therefore, how to reduce the exposure time of the unsupported foundation pit in order to reduce the deformation of the foundation pit is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a support system for foundation pits and its construction method, which can reduce the exposure time of foundation pits without support, thereby effectively reducing the spatiotemporal effect of the ground wall during the formation of a support and effectively controlling the deformation of the foundation pit.

[0005] To solve the above-mentioned technical problems, the present invention provides a support system for a foundation pit, the support system for the foundation pit comprising: a first support system, a second support system, ..., an nth support system distributed from top to bottom, and steel supports, where n is an integer greater than or equal to 3; the steel supports are detachably installed on the first area where the last section of earthwork excavation of the nth layer is completed.

[0006] Optionally, the foundation pit support system further includes a concrete backing, positioned above the transverse and longitudinal concrete supports of the nth support system.

[0007] Optionally, in the aforementioned foundation pit support system, one end of the steel support rests against the concrete backing, and the other end is connected to a jack that abuts against the backing steel plate of the ground wall.

[0008] Optionally, in the support system of the foundation pit, the number of steel supports is at least one.

[0009] Optionally, in the support system of the foundation pit, the steel support is a steel pipe, a steel section, or a lattice structure.

[0010] Optionally, in the aforementioned foundation pit support system, each support system includes: transverse concrete supports, longitudinal concrete supports, columns, and walers.

[0011] The present invention also provides a construction method for a support system for a foundation pit, the construction method comprising:

[0012] S1: Construct engineering piles, column piles, and retaining walls according to the design documents and construction plan;

[0013] S2: Excavate the first layer of earthwork, the second layer of earthwork, ..., the (n-1)th layer of earthwork in sequence to form the first support system, the second support system, ..., the (n-1)th support system; where n is an integer greater than or equal to 3;

[0014] S3: Excavate the nth layer of earthwork. In the first area after the excavation of the last section of the nth layer of earthwork, steel supports can be detachably installed to form the nth support system. The first active control load is applied to the steel supports using jacks and a servo system.

[0015] S4: Excavate the (n+1)th layer of earthwork. After the strength of the transverse concrete support of the nth support system meets the loading requirements, apply the second active control load to the transverse concrete support of the nth support system using jacks and a servo system.

[0016] S5: When the second active control load is greater than or equal to the first active control load of the corresponding steel support, the steel support shall be unloaded and removed.

[0017] S6: Repeat steps S3 to S5 until the construction of all remaining support systems is completed.

[0018] Optionally, in the construction method of the foundation pit support system, step S2 includes:

[0019] Excavate each layer of soil and construct transverse concrete supports, longitudinal concrete supports, columns, and walers to form the support system for the corresponding layer.

[0020] Optionally, in the construction method of the foundation pit support system, step S3, the detachable installation of steel supports in the first area after the final section of earthwork excavation in the nth layer includes:

[0021] Concrete backing is constructed above the transverse and longitudinal concrete supports of the nth support system.

[0022] One end of the steel support is placed against the concrete backing, and the other end is connected to a jack and pushed onto the back steel plate of the floor wall.

[0023] Optionally, in the construction method of the foundation pit support system, the construction process of the rear lining steel plate is as follows:

[0024] Embed the backing steel plate at the predetermined location in the wall; or,

[0025] It is placed after the excavation of the nth layer of earthwork.

[0026] In the foundation pit support system and construction method provided by this invention, the foundation pit support system includes a first support system, a second support system, ..., an nth support system distributed from top to bottom, and steel supports, where n is an integer greater than or equal to 3; the steel supports are detachably installed on the first area where the last section of earthwork excavation in the nth layer is completed. By installing temporary steel supports at the end of the construction of a concrete support system, the exposure time of the foundation pit without support is reduced, thereby effectively reducing the spatiotemporal effect of the ground wall during the formation of a support system and effectively controlling the deformation of the foundation pit. In addition, since both the steel supports and the concrete supports can use servo systems, they can actively apply loads to the foundation pit, thereby actively controlling the deformation of the foundation pit and further ensuring the control of micro-deformation of the foundation pit. Attached Figure Description

[0027] The above and other objects, features and advantages of this disclosure will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0028] Figure 1 This is a plan view of a portion of the third support system using steel supports in one embodiment of the present invention;

[0029] Figure 2 This is a schematic elevation view of a portion of the third support system using steel supports in one embodiment of the present invention;

[0030] Figure 3 This is a plan view of a portion of the third support system in an embodiment of the present invention, which uses a combination of steel support and concrete support.

[0031] Figure 4 This is a schematic elevation view of a third support system in one embodiment of the present invention, where a combination of steel and concrete supports is used in a partial manner.

[0032] Figure 5 Is it demolition? Figure 3 A schematic diagram of the plan view after the support is provided by China Steel.

[0033] Figure 6 Is it demolition? Figure 4 Elevation view of the structure supported by China Steel;

[0034] Figure 7 This is a flowchart of the construction method of the foundation pit support system in one embodiment of the present invention.

[0035] In the picture:

[0036] 1-Horizontal concrete support; 2-Longitudinal concrete support; 3-Column, 4-Column pile; 5-Enclosure; 6-Wall; 7-Concrete backing; 8-Steel support; 9-Jack; 10-Rear steel plate; X1-First support system; X2-Second support system; X3-Third support system. Detailed Implementation

[0037] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a more comprehensive understanding of the foundation pit support system and its construction method proposed in this invention. The advantages and features of this invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise scales, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0038] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0039] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0041] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0042] This embodiment provides a construction method for a support system for a foundation pit. Refer below to sections 1 to 2. Figure 7 This embodiment details the construction method of the foundation pit support system. In the figure, S1 represents the outer soil layer of the foundation pit and S2 represents the inner soil layer of the foundation pit.

[0043] First, execute step S1, and construct engineering piles, column piles 4 and retaining walls 5 according to the design documents and construction plan;

[0044] Next, step S2 is executed, sequentially excavating the first layer of earth, the second layer of earth, ..., the (n-1)th layer of earth, forming the first support system X1, the second support system X2, ..., the (n-1)th support system; where n is an integer greater than or equal to 3. Specifically, for each layer of earth excavation, transverse concrete supports 1, longitudinal concrete supports 2, columns 3, and walers 6 are constructed to form the support system for the corresponding layer.

[0045] Next, step S3 is executed, excavating the nth layer of earthwork. In the first area where the last section of earthwork in the nth layer is excavated, a detachable steel support 8 is installed, forming the nth support system. A first active control load is applied to the steel support 8 using jacks 9 and a servo system, along with a concrete backing 7. Here, the temporary steel support 8 is installed before the lower transverse concrete support 1 (i.e., the n+1th layer of earthwork) is constructed. The steel support 8 and its corresponding system can also be applied to the second support system X2, and can be used on several or one support system as needed.

[0046] By installing temporary steel supports at the end of the construction of a concrete support system, the exposure time of the foundation pit without support is reduced, thereby effectively reducing the spatiotemporal effect of the ground wall during the formation of the support and effectively controlling the deformation of the foundation pit.

[0047] Preferably, the model and specifications of the jack 9 can be the same or different, depending on the needs.

[0048] For details, please refer to Figures 1 to 4The detachable steel support 8 installed in the first area after the final section of earthwork excavation in the nth layer includes: constructing a concrete backing 7 above the transverse concrete support 1 and longitudinal concrete support 2 of the nth support system; placing one end of the steel support 8 on the concrete backing 7, and connecting the other end to a jack 9 to push it onto the rear lining steel plate 10 of the ground wall 5. Here, the rear lining steel plate 10 can be pre-embedded at a predetermined position in the ground wall, or installed after the excavation of the nth layer of earthwork.

[0049] Next, step S4 is executed to excavate the (n+1)th layer of earthwork. After the strength of the transverse concrete support 1 of the nth support system meets the loading requirements, the second active control load is applied to the transverse concrete support 1 of the nth support system using the jack 9 and the servo system.

[0050] The jack 9 is placed in the groove of the waler 6, or a double waler can be used in some areas with a groove in the middle.

[0051] Next, for reference Figure 5 and Figure 6 In step S5, when the second active control load is greater than or equal to the first active control load of the corresponding steel support 8, the steel support 8 is unloaded and removed. It is understood that the steel support 8 can be removed as needed, or retained to provide support together with the transverse concrete support 1. Both the steel support and the concrete support can employ a servo system, which can actively apply loads to the foundation pit, thereby actively controlling the deformation of the foundation pit and more effectively ensuring the control of micro-deformation of the foundation pit.

[0052] Next, proceed to step S6, and repeat steps S3 to S5 until the construction of all remaining support systems is completed.

[0053] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0054] In another embodiment, the present invention also provides a support system for a foundation pit, please refer to... Figure 1 and Figure 2 The foundation pit support system includes: a first support system X1, a second support system X2, ..., an nth support system distributed from top to bottom, and steel supports 8, where n is an integer greater than or equal to 3; the steel supports 8 are detachably installed on the first area where the last section of earthwork excavation in the nth layer is completed. Each support system includes: a transverse concrete support 1, a longitudinal concrete support 2, a column 3, and a waler 6 or a capping beam.

[0055] In this embodiment, n=3, the first support system X1, the second support system X2 and the third support system X3 are first formed, and the steel support 8 is detachably installed on the first area after the last section of earthwork excavation in the third layer is completed.

[0056] Furthermore, the support system for the foundation pit also includes a concrete backing 7, which is positioned above the transverse concrete support 1 and the longitudinal concrete support 2 of the nth support system. Specifically, one end of the steel support 8 rests on the concrete backing 7, and the other end is connected to a jack 9 and supported by the rear lining steel plate 10 of the ground wall.

[0057] In this embodiment, the number of steel supports 8 is at least one. The steel support 8 can be detachably installed on at least one transverse concrete support 1 in the middle of the nth layer of the ground wall. That is, it can be used on one or several transverse concrete supports 1 in the middle of the ground wall, or it can be used on all transverse concrete supports 1. The steel support 8 is preferably a steel pipe, but it can also be made of structural steel or a lattice structure.

[0058] In summary, the foundation pit support system and its construction method provided by this invention include a first support system, a second support system, ..., an nth support system distributed from top to bottom, and steel supports, where n is an integer greater than or equal to 3. The steel supports are detachably installed on the first area where the last section of earthwork excavation in the nth layer is completed. By installing temporary steel supports at the end of the construction of a concrete support system, the exposure time of the foundation pit without support is reduced, thereby effectively reducing the spatiotemporal effect of the ground wall during the formation of the support system and effectively controlling the deformation of the foundation pit. Furthermore, since both the steel supports and the concrete supports can use servo systems, they can actively apply loads to the foundation pit, thereby actively controlling the deformation of the foundation pit and further ensuring the control of micro-deformation of the foundation pit.

[0059] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method of constructing a support system for an excavation, characterized by, Comprise: S1: according to the design file and construction scheme, construction engineering pile, column pile (4) and enclosure (5); S2: first, second, …, n-1 layer of earthwork is excavated in turn, and first, second, …, n-1 support system is formed; Wherein, n is an integer greater than or equal to 3; Wherein, excavate each layer of earthwork, construction of horizontal concrete support (1), longitudinal concrete support (2), column (3) and surrounding purlin (6), to form the support system of the corresponding layer; S3: excavate the n layer of earthwork, and the first block area of the n layer of earthwork is excavated in the last partition, and the steel support (8) is detachably installed, and the n support system is formed, and the first active control load is applied to the steel support (8) by using the jack (9) and the servo system; Wherein, the first block area of the n layer of earthwork is excavated in the last partition, and the steel support (8) is detachably installed, and the n support system is formed, and the first active control load is applied to the steel support (8) by using the jack (9) and the servo system; It comprises: The concrete back (7) is constructed above the horizontal concrete support (1) and the longitudinal concrete support (2) of the n support system; One end of the steel support (8) is placed on the concrete back (7), and the other end is connected to the back lining steel plate (10) of the ground wall (5) by the jack (9); S4: excavate the n+1 layer of earthwork, and when the strength of the horizontal concrete support (1) of the n support system meets the loading requirement, the second active control load is applied to the horizontal concrete support (1) of the n support system by using the jack (9) and the servo system; S5: when the second active control load is greater than or equal to the first active control load of the corresponding steel support (8), the steel support (8) is unloaded and removed; S6: repeat S3 to S5 until the construction of all the remaining support systems is completed; Wherein, the number of the steel support (8) is at least one, and the steel support (8) is steel pipe, profile steel or lattice member.

2. The construction method of a support system of a foundation pit according to claim 1, wherein The construction process of the back lining steel plate (10) is as follows: The back lining steel plate (10) is embedded at the predetermined position of the ground wall; Or, After the n layer of earthwork is excavated, it is placed behind.

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