Axial force servo type enclosure structure and construction method

Abstract

The invention relates to an axial force servo type enclosure structure and a construction method, pre-stress is applied to preset axial force by using jacks in a first support area and a next support area, and counter-force is provided for the next group of jacks by using an inner structure part, the first support area and passive area soil pressure; earth is excavated to a second support, a second horizontal support body and an inner structure part are constructed, the second support and a jack in a next support area are used for applying prestress to preset axial force, and next layer of earth is excavated; and the previous step is repeated, the Nth layer of soil body is excavated to the lowermost horizontal supporting body, and the lowermost layer of earthwork is excavated after the lowermost horizontal supporting body and the jack in the pit bottom area exert the pre-stress to the preset axial force. Before the foundation pit is excavated to the preset elevation, the initial prestress is applied to the corresponding point position, large deformation of the enclosure structure caused by the fact that no effective supporting point exists on the earth excavation face can be effectively reduced, and protection on the surrounding environment is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of construction engineering, and more specifically, to an axial force servo type retaining structure and a construction method thereof. Background Art

[0002] At present, with the acceleration of the urbanization process and the increasing reduction of land resources, various urban buildings have started to develop towards the underground space. There are more and more deep foundation pit projects in the city, and they are getting deeper and deeper. It is becoming more and more difficult to carry out high-precision foundation pit construction under complex geological conditions. In addition, the strata in many places of deep foundation pit projects are basically saturated water-containing flowing plastic or soft plastic clay layers, and the deformation and displacement during the construction of deep foundation pits have a greater impact on the construction. To reduce the impact of soil excavation on the surrounding environment, the current conventional method is to shorten the exposure time as much as possible after unloading the foundation pit soil and form effective support as soon as possible. Since it takes a long time for concrete to reach the design strength, and the construction of super-large and super-deep foundation pits is very difficult in itself. Simply increasing the manpower and material resources to rush the progress can no longer meet the actual requirements, and simply changing the form of support will also affect the overall stability of the internal support. Summary of the Invention

[0003] The purpose of the present invention is to provide an axial force servo type retaining structure and a construction method thereof to solve the problems existing in the prior art.

[0004] The purpose of the present invention is achieved as follows: An axial force servo type retaining structure includes:

[0005] A retaining structure body (1);

[0006] An inner structure part;

[0007] A plurality of layers of horizontal support bodies (3) spaced apart from top to bottom, and the horizontal support bodies (3) horizontally support the inner wall of the inner structure part outward;

[0008] A plurality of groups of jacks with adjustable telescopic lengths for applying initial prestress at corresponding positions, the jacks are fixed between the retaining structure body (1) and the inner structure part, and both ends of the jacks press against the retaining structure body (1) and the inner structure part in the horizontal direction. Each group of jacks is horizontally aligned with a layer of horizontal support body (3), and jacks are distributed in the bottom plate area and the bottom of the pit.

[0009] Further, a lowering channel (14) extending vertically is provided in the inner structure part, and the jacks are placed in the lowering channel (14) through lowering.

[0010] Further, it further includes a plurality of embedded parts (7), and the embedded parts (7) are distributed inside the retaining structure body (1) and in the inner structure part for reducing stress concentration and preventing the concrete from being crushed.

[0011] Furthermore, a steel strand (15) is provided, and the steel strand (15) is used to connect a number of jacks in series.

[0012] Furthermore, the inner structural part includes an inner built-in structure (5) and a horizontally arranged inner built-in ring beam (2). The inner built-in structure (5) and the inner built-in ring beam (2) are fixedly connected as a whole. The inner built-in structure (5) is located between the inner built-in ring beam (2) and the enclosure structure (1), and the horizontal support (3) is fixedly connected to the inner side of the inner built-in ring beam (2).

[0013] Furthermore, the inner built-in structure (5) is provided as a diaphragm wall or an inner built-in row of piles.

[0014] Furthermore, the enclosure structure (1) is provided as a wall formed by fixedly splicing a number of units, or a pile group formed by a number of rows of piles.

[0015] As another aspect of the present invention, a construction method is proposed based on the above structure, which generally includes the following steps:

[0016] 1) Locate and construct the enclosure structure and the inner structural part, and open a channel for lowering the jacks.

[0017] 2) Lower the jacks to a predetermined position in the channel.

[0018] 3) Wait until the first horizontal support is constructed and reaches the design strength.

[0019] 4) Apply prestress to a predetermined axial force by using the jacks in the first support and the next support area, and use the inner structural part, the first support and the passive earth pressure to provide reaction force for the next group of jacks.

[0020] 5) Excavate the soil to the second support and construct the second horizontal support and the inner structural part. After the second horizontal support and the inner structural part reach the design strength, apply prestress to a predetermined axial force by using the second support and the jacks in the next support area, and excavate the next layer of soil.

[0021] 6) Repeat the fifth step, excavate the Nth layer of soil to the lowest horizontal support. After applying prestress to a predetermined axial force by using the lowest support and the jacks in the bottom area of the pit, excavate the lowest layer of soil, and construct the basement floor.

[0022] The beneficial effects of the present invention are as follows:

[0023] Before the foundation pit is excavated to the predetermined elevation, initial prestress is applied at the corresponding points, which can effectively reduce the large deformation of the enclosure structure caused by the lack of effective support points at the soil excavation surface, and strengthen the protection of the surrounding environment. Description of the Drawings

[0024] Figure 1It is the top view of an axial force servo type retaining structure and construction method in Embodiment 1 of the present invention.

[0025] Figure 2 It is the detail drawing of A-A in Embodiment 1 and Embodiment 2 of the present invention.

[0026] Figure 3 It is the detail drawing of B-B in Embodiment 1 and Embodiment 2 of the present invention.

[0027] Figure 4 It is the detailed drawing of the jack lowering structure in Embodiment 1 of the present invention.

[0028] Figure 5 It is the top view of an axial force servo type retaining structure and construction method in Embodiment 2 of the present invention.

[0029] Figure 6 It is the detailed drawing of the embedded cushion block in Embodiment 2 of the present invention.

[0030] Figure 7 It is the detail drawing of C-C in Embodiment 2 of the present invention.

[0031] Figure 8 It is the detail drawing of D-D in Embodiment 2 of the present invention.

[0032] Figure 9 It is the first schematic diagram of the construction steps in Embodiment 1 and Embodiment 2 of the present invention.

[0033] Figure 10 It is the second schematic diagram of the construction steps in Embodiment 1 and Embodiment 2 of the present invention.

[0034] Explanation of reference numerals: retaining structure body 1, built-in ring beam 2, horizontal support body 3, loading pier 4, built-in structure body 5, rear jack 6, embedded part 7, mouth-shaped thin-walled iron sheet 8, column 9, embedded cushion block 10, fixed insertion rod 11, thin-walled iron sheet 12, advanced jack 13, lowering channel 14, steel strand 15, external ring beam 16. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the attached Figures 1-10 , and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] Embodiment 1

[0037] Such as Figures 1-4 And Figures 9-10As shown in the figure, the retaining structure of the first embodiment adopts a diaphragm wall structure. Specifically, during implementation, it includes the following steps:

[0038] 1) Locate and construct the retaining structure body 1 and the column 9, and construct the built-in structure body 5 at the predetermined position. In the first embodiment, the built-in structure body 5 is set as a T-shaped diaphragm wall. Among them, embedded parts 7 are pre-embedded in the steel reinforcement cages of the retaining structure body 1 and the built-in structure body 5, and the positions where the embedded parts 7 are pre-embedded are the same as the positions where the jacks are installed, thus serving as the positioning basis for the jacks. Considering construction errors, steel plates slightly larger than the design size can be appropriately used for the embedded parts 7. A mouth-shaped thin-walled iron sheet 8 is fixed in the area of the steel reinforcement cage of the built-in structure body 5 where the jacks are placed, so as to form a lowering channel 14 for lowering the jacks after the built-in structure body 5 is poured with concrete. Therefore, the inner wall of the lowering channel 14 is a strengthened surface to prevent soil collapse; a thin-walled iron plate 12 is provided in the intersecting area between the built-in structure body 5 and the retaining structure body 1.

[0039] 2) Place the advanced jack 13 in the lowering jack channel to the predetermined elevation, and construct the first horizontal support body 3; the advanced jacks 13 are connected in series by steel strands 15, which is convenient for lowering and installation and prevents falling off.

[0040] 3) After the first support 3 is constructed and reaches the design strength, install the rear jack 6, and apply prestress to the advanced jacks 13 and the rear jack 6 in the area of the first support and the next support to the predetermined axial force; use the built-in structure body 5, the first support and the passive soil pressure to provide reaction force for the next advanced jack 13.

[0041] 4) Excavate the soil to the second support and construct the second horizontal support body 3, the built-in ring beam 2 and the loading pier 4; after the second horizontal support body 3, the built-in ring beam 2 and the loading pier 4 reach the design strength, apply prestress to the advanced jacks 13 in the area of the second support and the next support to the predetermined axial force, and excavate the next layer of soil. The excavated plane corresponds to the position of a group of jacks.

[0042] 5) Repeat step (4) to excavate the Nth layer of soil to the bottommost horizontal support body 3. After applying prestress to the advanced jacks 13 in the area of the bottommost support and the pit bottom to the predetermined axial force, excavate the bottommost layer of soil and construct the basement floor.

[0043] In addition, the advanced jacks 13 and the rear jacks 6 can be used in combination, or the advanced jack 13 scheme can be adopted entirely.

[0044] Embodiment Two

[0045] As Figures 5-8 and Figures 9-10 shown, the retaining structure of this embodiment adopts a row of piles structure. The row of piles can be bored piles, steel sections or PC method piles, and is not limited thereto. Specifically, during implementation, it includes the following steps:

[0046] 1) Locate and construct the retaining structure 1 and the columns 9, and construct the built-in structure 5 at the predetermined position. In the second embodiment, the built-in structure 5 is set as the built-in row of piles. Among them, the retaining structure 1 and the built-in structure 5 are fixedly connected with embedded cushion blocks 10, and the fixed insertion rods 11 (which fixedly insert into the piles of the retaining structure 1) are fixed on the embedded cushion blocks 10. The embedded position of the embedded cushion blocks 10 is consistent with the installation position of the jacks. Considering construction errors, the embedded cushion blocks 10 can be appropriately made larger than the design size.

[0047] 2) Use high-pressure jet grouting piles or earth excavation equipment to excavate the soil between the retaining structure 1 and the built-in structure 5 (built-in row of piles) to form a lowering channel 14. The lowering channel 14 adopts a retaining system such as slurry wall protection or steel sheet piles, and the inner wall of the lowering channel 14 is surface-strengthened to prevent soil collapse.

[0048] 3) Place the advanced jacks 13 in the lowering channel 14 to the predetermined elevation, and construct the first horizontal support 3; use steel strands 15 to connect several advanced jacks 13 in series, which is convenient for lowering and installing the jacks and preventing the jacks from falling off.

[0049] 4) After the first horizontal support 3 is constructed and reaches the design strength, apply prestress to the advanced jacks 13 in the first support and the next support area to the predetermined axial force; use the built-in structure 5 (built-in row of piles), the first support and the passive zone soil pressure to provide reaction force for the next advanced jack 13.

[0050] 5) Excavate the soil to the second support and construct the second horizontal support 3, the external ring beam 16, the internal ring beam 2 and the loading pier 4; after the second horizontal support 3, the external ring beam 16, the internal ring beam 2 and the loading pier 4 reach the design strength, apply prestress to the advanced jacks 13 in the second support and the next support area and the installed rear jacks 6 to the predetermined axial force, and excavate the next layer of soil. The advanced jacks 13 are placed above or below the external ring beam 16 according to the design.

[0051] 6) Repeat step (5) to excavate the Nth layer of soil to the lowest horizontal support 3. After applying prestress to the advanced jacks 13 in the lowest support and the bottom area of the pit to the predetermined axial force, excavate the lowest layer of soil and construct the basement floor slab.

[0052] In addition, the advanced jacks 13 and the rear jacks 6 can be used in combination, or the scheme of all using the advanced jacks 13 can also be adopted.

[0053] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings. 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. Therefore, it should not be construed as a limitation to the present invention. In the present invention, it should also be noted that the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, an integrally formed connection, a mechanical connection, or an indirect connection through an intermediate connecting member. The specific meaning of the terms in this utility model can be understood according to specific circumstances.

[0054] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes that fall within the meaning and scope of the equivalent elements of the claims in the present invention, and any reference signs in the claims should not be regarded as limiting the claims involved.

[0055] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An axial force servo type retaining structure, characterized in that Comprising: Enclosing structure body; Inner structure part; A number of horizontally arranged support bodies spaced from top to bottom, the horizontally arranged support bodies horizontally and outwardly support the inner wall of the inner structure part; A number of groups of jacks with adjustable telescopic lengths for applying initial prestress at corresponding positions, the jacks are fixed between the enclosing structure body and the inner structure part, both ends of the jacks horizontally press against the enclosing structure body and the inner structure part, each group of jacks is horizontally aligned with one layer of horizontally arranged support body, and jacks are distributed in the bottom plate area and the bottom of the pit.

2. The axial force servo type retaining structure according to claim 1, wherein A lowering channel extending vertically is provided in the inner structure part, and the jacks are placed in the lowering channel through lowering.

3. The axial force servo type retaining structure according to claim 2, characterized in that, It further comprises a number of embedded parts, and the embedded parts are distributed on the inner side of the enclosing structure body and in the inner structure part for reducing stress concentration and preventing the concrete from being crushed.

4. The axial force servo type retaining structure according to claim 2, characterized in that, Steel strands are also provided, and the steel strands are used to connect a number of jacks in series.

5. A shaft force servo type retaining structure according to any one of claims 1-4, characterized in that, The inner structure part comprises an inner built-in structure and an inner built-in ring beam arranged horizontally, the inner built-in structure and the inner built-in ring beam are fixedly connected as a whole, the inner built-in structure is located between the inner built-in ring beam and the enclosing structure body, and the horizontally arranged support body is fixedly connected to the inner side of the inner built-in ring beam.

6. The axial force servo type retaining structure according to claim 5, characterized in that, The inner built-in structure is set as a diaphragm wall or an inner built-in row of piles.

7. The axial force servo type retaining structure according to claim 5, characterized in that, The enclosing structure body is set as a wall formed by fixedly splicing a number of units, or a pile body group formed by a number of rows of piles.

8. A construction method based on the structure described in claim 1, characterized in that, Comprising the following steps: 1) Locate and construct the enclosing structure body and the inner structure part, and open a channel for lowering the jacks; 2) Lower the jacks to a predetermined position in the channel; 3) Wait until the first horizontal support is constructed and reaches the design strength; 4) Use the jacks in the area of the first support and the next support to apply prestress to a predetermined axial force, and use the inner structure part, the first support and the passive earth pressure to provide reaction force for the next group of jacks; 5) Excavate the soil to the second support and construct the second horizontal support body and the inner structure part. After the second horizontal support body and the inner structure part reach the design strength, use the jacks in the area of the second support and the next support to apply prestress to a predetermined axial force, and excavate the next layer of soil; 6) Repeat the fifth step, excavate the Nth layer of soil to the bottommost horizontal support body. After the jacks in the area of the bottommost support and the bottom of the pit apply prestress to a predetermined axial force, excavate the bottommost layer of soil, and construct the basement floor slab.

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