A foundation pit support structure and construction method thereof

Abstract

The present invention provides a foundation pit support structure and a construction method thereof, wherein the foundation pit support structure comprises: a foundation pit, prefabricated support piles and steel supports. The prefabricated support piles are arranged around the side wall of the foundation pit, and a first bottom plate and a second bottom plate are arranged in the foundation pit, wherein the first bottom plate is located on the inner side of the prefabricated support piles, and the second bottom plate is located on the side of the first bottom plate away from the prefabricated support piles, and a plurality of anchor bars arranged in a horizontal direction are pre-buried in the second bottom plate, and the ends of the anchor bars extend to the top of the first bottom plate and are connected with anchor plates; a steel sleeve is pre-fabricated at the elevation corresponding to the second bottom plate on the prefabricated support piles, and a waist beam is arranged on the steel sleeve, and a steel plate is pre-buried on the side of the waist beam facing the anchor plate; the two ends of the steel support are respectively supported between the steel plate and the anchor plate. The foundation pit support structure is reasonably designed, economical and applicable, can effectively utilize the site space, increase the excavation space, and speed up the construction period, and can meet the requirements of ensuring the safety of the foundation pit project, controlling the deformation of the surrounding environment of the foundation pit, and facilitating the construction of the project during the excavation of the foundation pit.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit construction, and in particular to a foundation pit supporting structure and a construction method thereof. Background Art

[0002] With the continuous expansion of urban scale and the continuous improvement of people's living standards, the current demand for the use of underground space is increasing. The excavation of deep foundation pits in deep soft soil areas in cities faces the difficult problems of how to ensure the safety of foundation pit projects, control the deformation of the environment around the foundation pits, and facilitate engineering construction.

[0003] Zhuhai City, Guangdong Province is located in the coastal area, where thick silt layers are common. Due to the limited anchor tension provided by soft soil such as silt, and the large relaxation and deformation of anchor rods after construction, coupled with the restrictions on anchor rods by the red line of the building land, pile (wall) internal support structure is often an ideal choice. In such areas, when the foundation pit is excavated to the bottom of the pit, there is often a problem of excessive deep displacement, which causes the foundation pit to deform and requires later reinforcement. In general, after setting up angle braces or other internal supports in the foundation pit, they can only rely on their stiffness to provide support force to control displacement. It is not convenient to apply prestress and cannot better control the deformation of the foundation pit (trench). Summary of the invention

[0004] The purpose of the present invention is to provide a foundation pit supporting structure to solve the shortcomings and deficiencies in the prior art.

[0005] A foundation pit support structure of the present invention comprises a foundation pit, prefabricated support piles and steel supports.

[0006] The prefabricated support piles are arranged vertically around the side walls of the foundation pit, and a first bottom plate and a second bottom plate are provided in the foundation pit, the first bottom plate is located on the inner side of the prefabricated support piles, and the second bottom plate is located on the side of the first bottom plate away from the prefabricated support piles, and the depth of the first bottom plate is greater than that of the second bottom plate; a plurality of anchor bars arranged in a horizontal direction are pre-embedded in the second bottom plate, and the ends of the anchor bars extend to the top of the first bottom plate, and the ends of the anchor bars are connected to the anchor plates; a steel sleeve is pre-fabricated on the prefabricated support pile at the elevation corresponding to the second bottom plate, a waist beam is provided on the steel sleeve, and a steel plate is pre-embedded on the side of the waist beam facing the anchor plate; when a monitoring value alarm is detected in the foundation pit, the two ends of the steel support are respectively supported between the steel plate and the anchor plate.

[0007] Compared with the prior art, the foundation pit support structure of the present invention is provided with a steel casing reserved on the prefabricated support pile, and anchor bars and anchor plates connected to the anchor bars are embedded on the second bottom plate. When the monitoring value alarm appears in the foundation pit, a steel support is added between the steel plate and the anchor plate, thereby applying prestress to control displacement. The foundation pit support structure of the present invention is reasonably designed, economical and applicable, can effectively utilize the site space, increase the excavation space, speed up the construction period, and can meet the requirements of ensuring the safety of the foundation pit project, controlling the deformation of the surrounding environment of the foundation pit, and facilitating the construction of the project during the excavation of the foundation pit.

[0008] In a preferred or optional embodiment, the embedded depth of the anchor bar is not less than 800 mm.

[0009] In a preferred or optional embodiment, the number of the anchor bars is 9.

[0010] In a preferred or optional embodiment, the diameter of the anchor bar is 20 mm.

[0011] In a preferred or optional embodiment, a jack is further provided between the steel plate and the steel support.

[0012] In a preferred or optional embodiment, the waist beam includes concrete and U-bars, both ends of the U-bars are welded to the outer wall of the steel casing by double-sided welding, and the concrete is poured on the U-bars to form a rectangular structure.

[0013] In a preferred or optional embodiment, a cap beam is provided on the top of the prefabricated supporting pile.

[0014] In a preferred or optional embodiment, the length of the steel casing is 1600 mm. In order to better understand and implement the present invention, the present invention is described in detail below with reference to the accompanying drawings.

[0015] In a preferred or optional embodiment, a tenon is provided at the top of the prefabricated supporting pile, a tenon hole corresponding to the tenon is provided in the middle of the crown beam, and the tenon is butted against the tenon hole.

[0016] The foundation pit support structure of the present invention summarizes the foundation pit support engineering cases of the supporting structure in Zhuhai, Guangdong, refers to the case model of foundation pit support in soft soil areas, and focuses on combining the actual situation in on-site construction and the foundation pit monitoring data, and uses steel supports and embedded parts to control the influence of deep displacement of the foundation pit on the foundation pit. In the deep foundation pit in Hengqin area of ​​Zhuhai, there is often a problem of backfilling the foundation pit due to excessive deep displacement from the foundation pit to the bottom of the pit. Generally, the pre- and post-processing will at least delay the construction period, and various reinforcement measures in the later stage will at least increase the measures fee. Therefore, setting up reserved measures in advance can effectively save construction period and cost, and effectively control the occurrence of this problem.

[0017] The present invention also provides a construction method of a foundation pit support structure, which comprises the following steps:

[0018] S1. Make a plurality of prefabricated support piles, prefabricate a steel sleeve at the elevation corresponding to the shallower bottom plate on each prefabricated support pile, arrange a waist beam on the steel sleeve, and embed a steel plate on the outer side of the waist beam;

[0019] S2, excavating a foundation pit, arranging the plurality of prefabricated support piles vertically around the side wall of the foundation pit, with the steel plate facing the inside of the foundation pit;

[0020] S3. Mark the positions of the first bottom plate and the second bottom plate to be excavated in the foundation pit, wherein the depth of the first bottom plate is greater than that of the second bottom plate, and the position of the first bottom plate is close to the prefabricated support piles;

[0021] S4, excavating the second bottom plate in the foundation pit, and pre-burying a plurality of anchor bars in the second bottom plate, wherein the ends of the anchor bars can extend into the first bottom plate, and connecting the anchor plate to the ends of the anchor bars;

[0022] S5. Excavating the first bottom plate in the foundation pit. If a foundation pit monitoring value alarm occurs, connecting a steel support between the steel plate and the anchor plate; if no foundation pit monitoring value alarm occurs, continuing to excavate the first bottom plate.

[0023] The above construction method sets up reserve measures in advance, which can effectively save construction time and cost when the monitoring value alarm appears in the foundation pit, and effectively control the occurrence of this problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the foundation pit supporting structure of the present invention;

[0025] Figure 2 for Figure 1 A is an enlarged schematic diagram;

[0026] Figure 3 It is a structural schematic diagram of the anchor plate of the present invention;

[0027] Figure 4 It is a structural schematic diagram of the prefabricated supporting piles in the foundation pit supporting structure of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] It should be understood that, in the description of the present application, the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application 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 cannot be understood as a limitation on the present application. The terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated, that is, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In addition, unless otherwise specified, "multiple" means two or more.

[0030] It should be noted that, in the description of this application, unless otherwise clearly specified and limited, the terms "disposed", "connected", "connected", and "hollow" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0031] See also Figures 1 to 4 ,in Figure 1 It is a structural schematic diagram of the foundation pit supporting structure of the present invention, Figure 2 for Figure 1 A is an enlarged schematic diagram. Figure 3 is a schematic diagram of the structure of the anchor plate of the present invention, Figure 4 This is a structural schematic diagram of the prefabricated supporting piles in the foundation pit supporting structure of the present invention. This embodiment provides a foundation pit supporting structure, including a foundation pit 1, prefabricated supporting piles 2 and steel supports 3.

[0032] The prefabricated support piles 2 are arranged vertically around the side wall of the foundation pit 1, and a first bottom plate 11 and a second bottom plate 12 are arranged in the foundation pit 1, the first bottom plate 11 is located on the inner side of the prefabricated support piles 2, and the second bottom plate 12 is located on the side of the first bottom plate 11 away from the prefabricated support piles 2, and the depth of the first bottom plate 11 is greater than that of the second bottom plate 12; a plurality of anchor bars 4 arranged in a horizontal direction are pre-embedded in the second bottom plate 12, and the ends of the anchor bars 4 extend above the first bottom plate 11, and the ends of the anchor bars 4 are connected to anchor plates 5; a steel sleeve 6 is pre-fabricated on the prefabricated support piles 2 at an elevation corresponding to the second bottom plate 12, and a waist beam 7 is arranged on the steel sleeve 6, and a steel plate 8 is pre-embedded on the side of the waist beam 7 facing the anchor plate 5; when a monitoring value alarm is detected in the foundation pit 1, the two ends of the steel support 3 are respectively supported between the steel plate 8 and the anchor plate 5.

[0033] Compared with the prior art, the foundation pit support structure of the present invention is provided with a steel casing reserved on the prefabricated support pile 2, and anchor bars 4 and anchor plates 5 connected to the anchor bars 4 are embedded on the second bottom plate 12. When the monitoring value alarm appears in the foundation pit 1, a steel support 3 is added to support between the steel plate 8 and the anchor plate 5, so as to apply prestress to control the displacement. The foundation pit support structure of the present application is reasonably designed, economical and applicable, can effectively utilize the site space, increase the excavation space, speed up the construction period, and can meet the requirements of ensuring the safety of the foundation pit project, controlling the deformation of the surrounding environment of the foundation pit, and facilitating the construction of the project during the excavation of the foundation pit.

[0034] Deformation monitoring of foundation pit 1 generally monitors vertical displacement, horizontal displacement and deep displacement. On-site monitoring and measurement is particularly important for the support technology of complex foundation pit 1. Foundation pit 1 monitoring can grasp the stability and safety of foundation pit 1 and provide accurate data information so that the design and construction plan can be adjusted accordingly to achieve the optimization of design and construction and ensure the safety and stability of deep foundation pit 1 support. The monitoring value of foundation pit 1 can be carried out through common testing equipment, which will not be elaborated here.

[0035] The specific use process of the foundation pit support structure of the present invention is as follows:

[0036] In the first step, when the prefabricated supporting piles 2 are prefabricated, the manufacturer is required to prefabricate the steel sleeve 6 at the elevation of the shallower bottom plate (the second bottom plate 12 in this embodiment).

[0037] Step 2: Construction of foundation pit 1 During the construction of the second bottom plate 12, anchor bars 4 need to be pre-buried near the first bottom plate 11. When the deep channel of foundation pit 1 is excavated to the bottom of the pit (i.e., excavating the first bottom plate 11 to the bottom of the pit), if an alarm occurs in the monitoring value of foundation pit 1 (such as deep displacement, change rate alarm, etc.), the excavation of foundation pit 1 needs to be suspended, and it needs to be backfilled and counter-pressurized.

[0038] Step 3: After the monitoring change rate of foundation pit 1 tends to be stable, find out the pre-buried anchor bars 4 in the constructed bottom plate (second bottom plate 12) and connect the anchor plates 5 according to the method in the middle.

[0039] Step 4: When the transformation rate of the foundation pit 1 is within the specification requirements, prepare to add emergency steel supports 3. Add a waist beam 7 on the prefabricated support pile 2, and embed a steel plate 8 on the side of the waist beam 7 facing the anchor plate 5.

[0040] Step 5: Support the two ends of the steel support 3 between the steel plate 8 and the anchor plate 5. If the foundation pit 1 is stable during excavation, the steel support 3 may not be provided.

[0041] The foundation pit support structure of the present invention summarizes the foundation pit support engineering cases of the internal support structure in Zhuhai, Guangdong, refers to the case model of foundation pit support in soft soil areas, and focuses on combining the actual situation in on-site construction and the foundation pit monitoring data, and adopts steel support 3 and embedded parts to control the influence of deep displacement of the foundation pit on the foundation pit. In the deep foundation pit in Hengqin area of ​​Zhuhai, there is often a problem of backfilling the foundation pit due to excessive deep displacement from the foundation pit to the bottom of the pit. Generally, the pre- and post-processing will at least delay the construction period, and various reinforcement measures in the later stage will at least increase the measures fee. Therefore, setting up reserved measures in advance can effectively save construction period and cost, and effectively control the occurrence of this problem.

[0042] As an optional implementation, the pre-embedded depth of the anchor bar 4 is not less than 800 mm to ensure the connection strength of the anchor bar 4. Specifically, in this embodiment, the pre-embedded depth of the anchor bar 4 is 900 mm.

[0043] Furthermore, in this embodiment, the number of the anchor bars 4 is 9, the diameter of the anchor bars 4 is 20 mm, and the length of the steel casing is 1600 mm.

[0044] As an optional implementation, a jack 9 is further provided between the steel plate 8 and the steel support 3. By providing the jack 9, the prestress between the steel plate 8 and the steel support 3 is increased, so that the supporting effect of the steel support 3 is better. By starting the jack 9 so that the other end of the steel support 3 is pressed tightly against the anchor plate 5, the prestress can be slowly applied.

[0045] As an optional implementation, the waist beam 7 includes concrete 71 and U-ribs 72. Both ends of the U-ribs 72 are welded to the outer wall of the steel casing by double-sided welding. The concrete 71 is poured on the U-ribs 72 to form a rectangular structure. The waist beam 7 thus arranged has a firm structure and strong practicality.

[0046] As an optional implementation, a cap beam 21 is provided on the top of the prefabricated support pile 2 to prevent the top edge of the foundation pit 1 from collapsing. Preferably, a tenon (not shown) is provided on the top of the prefabricated support pile 2, and a tenon hole (not shown) corresponding to the tenon is provided in the middle of the cap beam 21, and the tenon is butted with the tenon hole, thereby facilitating the connection between the cap beam and the prefabricated support pile.

[0047] According to the above foundation pit supporting structure, the present invention also provides a construction method of the foundation pit supporting structure, which comprises the following steps:

[0048] S1. Make a plurality of prefabricated support piles 2, prefabricate a steel sleeve 6 at the elevation corresponding to the shallower bottom plate on each prefabricated support pile 2, arrange a waist beam 7 on the steel sleeve 6, and embed a steel plate 8 on the outer side of the waist beam 7;

[0049] S2, excavating a foundation pit 1, arranging the plurality of prefabricated support piles 2 vertically around the side wall of the foundation pit 1, with the steel plates 8 facing the inside of the foundation pit 1;

[0050] S3. Mark the positions of the first bottom plate 11 and the second bottom plate 12 to be excavated in the foundation pit 1, wherein the depth of the first bottom plate 11 is greater than that of the second bottom plate 12, and the position of the first bottom plate 11 is close to the prefabricated support piles 2;

[0051] S4, excavating the second bottom plate 12 in the foundation pit 1, and pre-burying a plurality of anchor bars 4 in the second bottom plate 12, wherein the ends of the anchor bars 4 can extend into the first bottom plate 11, and connecting the anchor plates 5 to the ends of the anchor bars 4;

[0052] S5, excavating the first bottom plate 11 in the foundation pit 1, if the foundation pit monitoring value alarm appears, connecting a steel support 3 between the steel plate 8 and the anchor plate 5; if the foundation pit monitoring value alarm does not appear, continue to excavate the first bottom plate 11. The above construction method sets up reserve measures in advance, which can effectively save construction time and cost when the foundation pit monitoring value alarm appears, and effectively control the occurrence of this problem.

[0053] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A foundation pit support structure, characterized in that: include: foundation pit, precast support piles and steel supports; The prefabricated support piles are arranged vertically around the side walls of the foundation pit, and a first bottom plate and a second bottom plate are arranged in the foundation pit, the first bottom plate is located on the inner side of the prefabricated support piles, and the second bottom plate is located on the side of the first bottom plate away from the prefabricated support piles, and the depth of the first bottom plate is greater than that of the second bottom plate; a plurality of anchor bars arranged in a horizontal direction are pre-embedded in the second bottom plate, and the ends of the anchor bars extend to the top of the first bottom plate, and the ends of the anchor bars are connected to the anchor plates; a steel sleeve is pre-fabricated on the prefabricated support pile at the elevation corresponding to the second bottom plate, a waist beam is arranged on the steel sleeve, and a steel plate is pre-embedded on the side of the waist beam facing the anchor plate; when a monitoring value alarm is detected in the foundation pit, the two ends of the steel support are respectively supported between the steel plate and the anchor plate.

2. The foundation pit support structure according to claim 1, characterized in that: The embedded depth of the anchor bar shall not be less than 800mm.

3. The foundation pit supporting structure according to claim 2 is characterized in that: The number of the anchor bars is 9.

4. The foundation pit supporting structure according to claim 3 is characterized in that: The diameter of the anchor bar is 20 mm.

5. The foundation pit supporting structure according to claim 1, characterized in that: A jack is also arranged between the steel plate and the steel support.

6. The foundation pit supporting structure according to claim 1, characterized in that: The waist beam includes concrete and U-bars, both ends of the U-bars are welded to the outer wall of the steel sleeve by double-sided welding, and the concrete is poured on the U-bars to form a rectangular structure.

7. The foundation pit supporting structure according to claim 1, characterized in that: A cap beam is arranged on the top of the prefabricated supporting pile.

8. The foundation pit supporting structure according to any one of claims 1 to 7, characterized in that: The length of the steel sleeve is 1600 mm.

9. The foundation pit supporting structure according to claim 7, characterized in that: A tenon is arranged on the top of the prefabricated supporting pile, a tenon hole corresponding to the tenon is arranged in the middle of the crown beam, and the tenon is butted against the tenon hole.

10. A construction method for a foundation pit support structure, characterized in that: The steps include: S1. Make a plurality of prefabricated support piles, prefabricate a steel sleeve at the elevation corresponding to the shallower bottom plate on each prefabricated support pile, arrange a waist beam on the steel sleeve, and embed a steel plate on the outer side of the waist beam; S2, excavating a foundation pit, arranging the plurality of prefabricated support piles vertically around the side wall of the foundation pit, with the steel plate facing the inside of the foundation pit; S3. Mark the positions of the first bottom plate and the second bottom plate to be excavated in the foundation pit, wherein the depth of the first bottom plate is greater than that of the second bottom plate, and the position of the first bottom plate is close to the prefabricated support piles; S4, excavating the second bottom plate in the foundation pit, and pre-burying a plurality of anchor bars in the second bottom plate, with the ends of the anchor bars extending into the first bottom plate, and connecting the anchor plate to the ends of the anchor bars; S5. Excavating the first bottom plate in the foundation pit. If a foundation pit monitoring value alarm occurs, connecting a steel support between the steel plate and the anchor plate; if no foundation pit monitoring value alarm occurs, continuing to excavate the first bottom plate.

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