Construction method of elevator foundation pit

Abstract

The invention belongs to the technical field of building construction, and discloses an elevator foundation pit construction method which comprises the following steps: determining a to-be-excavated position of an elevator foundation pit; a plurality of steel sheet piles are driven into the foundation, so that the steel sheet piles are arranged on the periphery of the peripheral side of the to-be-excavated position in a surrounding mode; carrying out internal earth excavation at the position to be excavated so as to form an operation pit; a caisson is lowered into the operation pit, and water is injected into the caisson after placement is completed; backfill concrete is poured into a gap between the bottom wall of the caisson and the bottom of the operation pit and a gap between the outer side wall of the caisson and the steel sheet pile, the steel sheet pile is pulled out before the backfill concrete is initially set, and then cushion layer concrete is poured on the top face of the foundation on the peripheral side of the operation pit; after the backfill concrete and the cushion concrete are finally set, water in the caisson is discharged; and constructing an underground structure in the caisson. The method can reduce the work amount of precipitation operation and improve the construction efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of building construction, and particularly relates to a construction method for an elevator pit. Background Art

[0002] In the technical field of building construction, underground foundation pit construction is an important part of infrastructure construction, which usually includes several key links such as earth excavation, foundation pit support, and groundwater control (dewatering). Among them, foundation pit construction, as an important process connecting the ground structure and the underground structure, requires effective control of soil stability and groundwater level on the premise of ensuring construction safety and quality.

[0003] In high-rise buildings and large public buildings, elevators are often required to meet the vertical transportation needs. As the foundation for elevator equipment installation, the elevator pit is usually located several meters below the bottom of the building foundation, with a large excavation depth. To ensure construction safety and foundation pit stability, the groundwater level needs to be lowered below the bottom of the elevator pit, resulting in increased dewatering work volume, long construction period, and high cost. At the same time, to ensure the stability of the deep foundation pit side wall, the foundation pit support structure needs to be strengthened. In this way, the construction difficulty increases under the condition of limited space, the construction efficiency is low, and there are relatively large potential safety hazards.

[0004] Therefore, there is an urgent need to propose a construction method for an elevator pit to solve the above technical problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a construction method for an elevator pit, which can reduce the work volume of dewatering operations and improve construction efficiency.

[0006] As conceived above, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a construction method for an elevator pit, including:

[0008] S1. Determine the proposed excavation location of the elevator pit;

[0009] S2. Drive a plurality of steel sheet piles into the foundation, so that the plurality of steel sheet piles surround the outer periphery of the proposed excavation location;

[0010] S3. Conduct internal earth excavation at the proposed excavation location to form a working pit;

[0011] S4. Lower the caisson into the working pit, and after placement, inject water into the caisson;

[0012] S5. Pour backfill concrete into the gaps between the bottom wall of the caisson and the bottom of the working pit, and between the outer sidewall of the caisson and the steel sheet piles. Pull out the steel sheet piles before the initial setting of the backfill concrete, and then pour cushion concrete on the top surface of the foundation on the periphery of the working pit.

[0013] S6. After the backfill concrete and the cushion concrete have finally set, drain the water inside the caisson.

[0014] S7. Construct the underground structure inside the caisson.

[0015] In some embodiments, before step S4, it further includes:

[0016] Lay bricks at the bottom of the working pit for leveling.

[0017] In some embodiments, the caisson is a top - open structure formed by connecting multiple steel plates; before step S4, it further includes:

[0018] Weld multiple steel plates together to form the caisson, and weld a support structure inside the caisson.

[0019] In some embodiments, after step S6, it further includes:

[0020] Demolish the support structure inside the caisson.

[0021] In some embodiments, the support structure is composed of multiple steel pipes welded together. The multiple steel pipes are arranged inside the caisson in two directions, horizontal and vertical, and the distance between any two adjacent steel pipes is not greater than 1.2 m.

[0022] In some embodiments, the steel plates at the sidewalls of the caisson all extend in the vertical direction.

[0023] In some embodiments, after welding multiple steel plates together to form the caisson and welding a support structure inside the caisson, it further includes:

[0024] Weld multiple anchor claws on the outer wall surfaces of the multiple steel plates.

[0025] In some embodiments, after welding multiple steel plates together to form the caisson and welding a support structure inside the caisson, it further includes:

[0026] Weld lifting rings for lifting the caisson on the top of the caisson. And in step S5, the cushion concrete covers the lifting rings.

[0027] In some embodiments, step S2 specifically includes:

[0028] Make the top surface of the steel sheet pile higher than the top surface of the foundation around the periphery of the proposed excavation position.

[0029] In some embodiments, step S7 specifically includes:

[0030] Perform waterproof construction, steel bar binding, formwork erection, and concrete pouring inside the caisson in sequence.

[0031] Advantages of the present invention:

[0032] The construction method of the elevator pit provided by the present invention forms a safe operation space by driving steel sheet piles, eliminating the need for additional foundation pit support construction, reducing the dependence on complex foundation pit support structures, lowering the construction difficulty and cost under space-constrained conditions, and improving construction efficiency. In addition, after forming the operation pit, the caisson is lowered and installed in the operation pit, and the caisson is integrated with the foundation by pouring concrete. Moreover, the construction of the underground structure of the subsequent elevator pit is carried out inside the caisson. In this way, the groundwater below the caisson can be isolated by the caisson, reducing or avoiding the need for dewatering operations, which is beneficial for reducing the amount of dewatering work and shortening the construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments of the present invention. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings.

[0034] Figure 1 is a schematic diagram of the proposed excavation position of the foundation provided by the embodiment of the present invention;

[0035] Figure 2 is a schematic diagram after forming the operation pit provided by the embodiment of the present invention;

[0036] Figure 3 is a schematic diagram of the structure of the caisson provided by the embodiment of the present invention;

[0037] Figure 4 is a schematic diagram of the caisson placed inside the operation pit provided by the embodiment of the present invention;

[0038] Figure 5 is a schematic diagram after pouring and backfilling concrete provided by the embodiment of the present invention;

[0039] Figure 6 is a schematic diagram when pulling out the steel sheet pile provided by the embodiment of the present invention;

[0040] Figure 7It is a schematic diagram of constructing an underground structure inside a caisson provided by an embodiment of the present invention.

[0041] In the figure:

[0042] 100, proposed excavation location; 200, foundation; 300, working pit;

[0043] 1, steel sheet pile;

[0044] 2, caisson; 21, steel plate; 22, lifting ring;

[0045] 3, backfill concrete;

[0046] 4, cushion concrete;

[0047] 5, underground structure. Detailed implementation manners

[0048] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0050] It should be noted that: like reference numerals and letters denote like items in the following accompanying drawings. Therefore, once an item is defined in one accompanying drawing, it does not need to be further defined and explained in subsequent accompanying drawings.

[0051] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is habitually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and cannot be construed as indicating or implying relative importance. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0052] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, the terms "arranged" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] In the present invention, unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "under" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0054] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, in which the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0055] As Figures 1 to 7 shown, the construction method of the elevator pit provided in this embodiment includes:

[0056] S1. Determine the proposed excavation position 100 of the elevator pit;

[0057] S2. Drive a plurality of steel sheet piles 1 into the foundation 200 so that the plurality of steel sheet piles 1 surround the periphery of the proposed excavation position 100;

[0058] S3. Conduct internal earth excavation at the proposed excavation position 100 to form an operation pit 300;

[0059] S4. Lower the caisson 2 into the operation pit 300, and after placement, inject water into the caisson 2;

[0060] S5. Pour backfill concrete 3 into the gap between the bottom wall of the caisson 2 and the bottom of the operation pit 300, and into the gap between the outer side wall of the caisson 2 and the steel sheet pile 1. Pull out the steel sheet pile 1 before the backfill concrete 3 starts to set, and then pour cushion concrete 4 on the top surface of the foundation 200 on the periphery of the operation pit 300;

[0061] S6. After the backfill concrete 3 and the cushion concrete 4 are finally set, drain the water inside the caisson 2;

[0062] S7. Construct the underground structure 5 inside the caisson 2.

[0063] Specifically, when performing step S2, first expand 300 mm outward on the basis of the periphery of the proposed excavation position 100 to position the steel sheet piles 1, and then drive multiple steel sheet piles 1 into the foundation 200. The multiple steel sheet piles 1 enclose to form a safe working space to ensure the construction safety at this part. Subsequently, the operation pit 300 is excavated (step S3). When performing step S4, injecting water into the caisson 2 can increase its own weight to ensure that the caisson 2 will not displace. The backfill concrete 3 and the cushion concrete 4 in step S5 can use C15 concrete. During the pouring process, pour symmetrically and evenly around. When pulling out the steel sheet piles 1, also pull out symmetrically around to prevent uneven stress from causing the caisson 2 to displace. After that, after the backfill concrete 3 and the cushion concrete 4 have finally set, at this time, the caisson 2 and the surrounding foundation 200 have been combined, and the water inside the caisson 2 can be drained to facilitate the subsequent construction inside the caisson 2 (step S6). Step S7 is to construct the underground structure 5 of the elevator pit inside the caisson 2. In this way, it is convenient to accurately position the underground structure 5 and make its quality easier to control.

[0064] The construction method of the elevator pit provided in this embodiment forms a safe working space by driving the steel sheet piles 1, eliminating the need for additional foundation pit support construction, reducing the dependence on complex foundation pit support structures, reducing the construction difficulty and cost under space-limited conditions, and improving the construction efficiency. In addition, after forming the operation pit 300, the caisson 2 is lowered and installed in the operation pit 300, and the caisson 2 and the foundation 200 are combined into one by pouring concrete. Moreover, the subsequent construction of the underground structure 5 of the elevator pit is carried out inside the caisson 2. In this way, the groundwater below the caisson 2 can be isolated by the caisson 2, reducing or avoiding the need for dewatering operations, which is beneficial to reducing the engineering quantity of dewatering operations and shortening the construction period.

[0065] Optionally, the foundation 200 includes but is not limited to a sand and gravel foundation.

[0066] Optionally, for draining the water inside the caisson 2 in step S6, the water can be drained by suction. Suction drainage is a mature existing technology in the field and will not be elaborated here.

[0067] In some embodiments, step S7 specifically includes:

[0068] Perform waterproof construction, steel bar binding, formwork erection and concrete pouring in sequence inside the caisson 2 to form the underground structure 5.

[0069] Among them, waterproof construction can effectively avoid groundwater seepage, ensure the service function and durability of the elevator pit, and reduce the later maintenance cost. Steel bar binding and formwork erection provide a stable framework for concrete pouring, ensure the strength and stability of the underground structure 5, and meet the bearing requirements of the elevator pit. Standardized concrete pouring ensures the quality of the formed structure, reduces the risk of quality defects caused by improper construction, and improves the construction quality.

[0070] In some embodiments, step S2 specifically includes:

[0071] Make the top surface of the steel sheet pile 1 higher than the top surface of the foundation 200 around the periphery of the proposed excavation position 100.

[0072] For example, the top elevation of the steel sheet pile 1 is 400 mm higher than the top elevation of the foundation 200 to facilitate subsequent pile pulling.

[0073] Such as Figure 4 As shown, in some embodiments, before step S4, it further includes:

[0074] Bricks are laid at the bottom of the working pit 300 for leveling.

[0075] With such a setting, it can be ensured that when the caisson 2 is placed inside the working pit 300, the bottom of the caisson 2 is in a horizontal state.

[0076] Such as Figure 3 As shown, the caisson 2 is a structure with an open top formed by connecting multiple steel plates 21. Among them, the thickness of the steel plate 21 includes but is not limited to 8 mm.

[0077] Before step S4, it further includes:

[0078] Weld multiple steel plates 21 together to form the caisson 2, and weld a support structure inside the caisson 2.

[0079] By welding a support structure inside the caisson 2, it is beneficial to enhance the stiffness and anti-deformation ability of the caisson 2, and is beneficial to avoid the steel plates 21 of the caisson 2 from being extruded and deformed.

[0080] Correspondingly, after step S6, it further includes: removing the support structure inside the caisson 2. That is: after the backfill concrete 3 and the cushion concrete 4 reach the designed strength after final setting, drain the water inside the caisson 2, and remove the support structure inside the caisson 2 to vacate the internal space of the caisson 2, facilitating subsequent construction inside the caisson 2.

[0081] In some embodiments, the support structure is composed of multiple steel pipes welded together. The multiple steel pipes are arranged inside the caisson 2 in the transverse and longitudinal directions, and the distance between any two adjacent steel pipes is not greater than 1.2 m.

[0082] With such a setting, a dense and stable support network can be constructed inside the caisson 2. The steel pipes arranged in the horizontal and vertical directions can effectively support the inside of the caisson 2 from multiple dimensions, enhancing the overall anti-deformation ability of the caisson 2.

[0083] As Figure 3 shown, in some embodiments, the steel plates 21 at the side walls of the caisson 2 all extend in the vertical direction.

[0084] In the construction of traditional elevator pits, a sloping design is mostly adopted. Therefore, when binding the steel bars of the underground structure 5 during construction, the steel bars need to be configured according to the angle and length of the inclined wall surface, resulting in an increase in the amount of steel bars used. In this embodiment, the steel bars are bound inside the caisson 2, and the steel plates 21 on the side walls of the caisson 2 all extend in the vertical direction. This vertical setting method greatly shortens the steel bar binding path, reduces unnecessary extended parts of the steel bars, is beneficial to reducing the amount of steel bars used, and saves materials.

[0085] In some embodiments, after welding a plurality of steel plates 21 together to form the caisson 2 and welding a support structure inside the caisson 2, it further includes:

[0086] Welding a plurality of anchor claws on the outer wall surfaces of the plurality of steel plates 21.

[0087] With such a setting, when pouring the backfill concrete 3, the anchor claws can be wrapped inside the backfill concrete 3. That is, by setting the anchor claws, the bonding strength between the caisson 2 and the backfill concrete 3 can be improved.

[0088] In some embodiments, after welding a plurality of steel plates 21 together to form the caisson 2 and welding a support structure inside the caisson 2, it further includes:

[0089] Welding a lifting ring 22 for lifting the caisson 2 on the top of the caisson 2. And, in step S5, the cushion concrete 4 covers the lifting ring 22.

[0090] The setting of the lifting ring 22 facilitates the lifting of the caisson 2. And, in step S5, the top surface of the lifting ring 22 does not exceed the top surface of the cushion concrete 4. In this way, after the cushion concrete 4 is poured, the lifting ring 22 will be wrapped inside, and there is no need to remove the lifting ring 22 anymore, reducing the construction procedures.

[0091] Note that the above is only a preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. The construction method of elevator foundation pit is characterized by: include: S1. Determine the proposed excavation position of the elevator foundation pit (100); S2, driving a plurality of steel sheet piles (1) into the foundation (200), so that the plurality of steel sheet piles (1) are arranged around the periphery of the planned excavation location (100); S3, performing internal earth excavation at the proposed excavation location (100) to form an operation pit (300); S4, lowering the caisson (2) into the working pit (300), and after the caisson (2) is placed, injecting water into the caisson (2); S5, pouring backfill concrete (3) into the gap between the bottom wall of the caisson (2) and the bottom of the working pit (300), and into the gap between the outer wall of the caisson (2) and the steel sheet piles (1), pulling out the steel sheet piles (1) before the backfill concrete (3) begins to set, and then pouring cushion concrete (4) on the top surface of the foundation (200) around the working pit (300); S6, after the backfill concrete (3) and the cushion concrete (4) have finally set, draining the water inside the caisson (2); S7. Construction of the underground structure (5) is carried out inside the caisson (2).

2. The elevator foundation pit construction method according to claim 1, characterized in that: Before step S4, the method further includes: Bricks are stacked at the bottom of the working pit (300) for leveling.

3. The elevator foundation pit construction method according to claim 1, characterized in that: The caisson (2) is a structure with an open top formed by connecting a plurality of steel plates (21); before step S4, the method further comprises: A plurality of the steel plates (21) are welded together to form the caisson (2), and a supporting structure is welded inside the caisson (2).

4. The elevator foundation pit construction method according to claim 3, characterized in that: After step S6, the method further includes: The supporting structure inside the caisson (2) is removed.

5. The elevator foundation pit construction method according to claim 3, characterized in that: The supporting structure is composed of a plurality of welded steel pipes, and the plurality of steel pipes are arranged inside the caisson (2) along both the horizontal and vertical directions, and the distance between any two adjacent steel pipes is no more than 1.2 m.

6. The elevator foundation pit construction method according to claim 3, characterized in that: The steel plates (21) at the side walls of the caisson (2) all extend in the vertical direction.

7. The elevator foundation pit construction method according to claim 3, characterized in that: After welding a plurality of the steel plates (21) together to form the caisson (2), and welding a supporting structure inside the caisson (2), the method further comprises: A plurality of anchor claws are welded to the outer wall surfaces of the plurality of steel plates (21).

8. The elevator foundation pit construction method according to claim 3, characterized in that: After welding a plurality of the steel plates (21) together to form the caisson (2), and welding a supporting structure inside the caisson (2), the method further comprises: A lifting ring (22) for lifting the caisson (2) is welded on the top of the caisson (2). Furthermore, in the step S5, the cushion concrete (4) covers the lifting ring (22).

9. The elevator foundation pit construction method according to any one of claims 1 to 8, characterized in that: The step S2 specifically includes: The top surface of the steel sheet pile (1) is made higher than the top surface of the foundation (200) on the periphery of the planned excavation position (100).

10. The elevator foundation pit construction method according to any one of claims 1 to 8, characterized in that: The step S7 specifically includes: Waterproofing construction, steel bar binding, formwork support and concrete pouring are carried out in sequence inside the caisson (2).

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