Local servo system of foundation pit concrete support structure and construction method thereof

Abstract

The present invention belongs to the technical field of foundation pit support construction, and discloses a local servo system of a foundation pit concrete support structure and a construction method thereof, which are used for supporting an underground continuous wall. The underground continuous wall is scientifically divided into a servo section and a non-servo section, which reduces costs, and the servo section is subdivided into a first servo area, a second servo area and a third servo area. The local servo system of the foundation pit concrete support structure includes a support structure and a plurality of servo jacks. The support structure can support the underground continuous wall. The plurality of servo jacks are used to provide supporting force, and different supporting forces are provided for the first servo area, the second servo area and the third servo area, which can control the deformation of the underground continuous wall and improve the stability of the foundation pit. The local servo system of the foundation pit concrete support structure and the construction method thereof can effectively control the deformation of the underground continuous wall, coordinate the deformation of the servo section and the non-servo section, and give full play to the overall bearing performance.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation pit support construction, and in particular to a local servo system of a foundation pit concrete support structure and a construction method thereof. Background Art

[0002] Foundation pit refers to the space below the ground excavated for the construction of foundations and basements of buildings (including structures). It is used in construction projects and is a temporary project. Its function is to provide a space so that the foundation masonry work can be carried out according to the position specified in the design. With the continuous advancement of large-scale underground engineering construction in cities, the number of projects near important transportation facilities, municipal pipelines, protective buildings, etc. continues to grow, and the requirements for controlling environmental disturbances such as deformation of underground continuous walls during foundation pit construction are becoming increasingly higher.

[0003] Setting up a support structure in the foundation pit is an important means of controlling the deformation of the underground continuous wall, which is a passive control method. In areas with high environmental protection requirements, a support servo system is often used to apply a constrained top force to strictly limit the deformation of the underground continuous wall, which is an active control method. The currently commonly used steel support servo system has a small bearing capacity and cannot meet the deformation control needs of deep and large foundation pits. It is often only used in narrow foundation pits. In the support field of deep and large foundation pits, there is a simple application of a concrete support servo system. However, the underground continuous wall has the characteristics of large deformation in the middle and small deformation in the corners. Some existing concrete support servo systems set all areas of the underground continuous wall as servo sections, which is costly and wastes materials and equipment. Some concrete support servo systems divide the underground continuous wall into servo sections and non-servo sections, but the regional node distinction is not scientific enough, and the deformation coordination of the servo section and the non-servo section cannot be guaranteed, and the overall bearing performance cannot be fully utilized to control the deformation of the underground continuous wall.

[0004] Therefore, there is an urgent need for a device to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a local servo system for the foundation pit concrete support structure, which scientifically divides the underground continuous wall into servo segments and non-servo segments to reduce costs, and subdivides the servo segments to provide different support forces for different areas, and can coordinate the servo segments and non-servo segments to effectively control the deformation of the underground continuous wall.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A local servo system for a foundation pit concrete support structure is used to support an underground continuous wall. The underground continuous wall is arranged on the side walls on opposite sides of the foundation pit and extends along the length direction. The underground continuous wall is provided with a servo section and two non-servo sections at the same height. The servo section is arranged between the two non-servo sections. The servo section includes two first servo areas, a plurality of second servo areas, and a plurality of third servo areas. The two first servo areas are located at the outermost ends of the servo section. Each first servo area is connected to a non-servo section in a one-to-one correspondence. The second servo area and the third servo area are located between the two first servo areas. The local servo system for the foundation pit concrete support structure includes:

[0008] a support structure comprising a purlin and a plurality of horizontal longitudinal braces disposed at intervals, wherein the horizontal longitudinal braces are connected to the underground continuous walls on both sides via the purlin, the horizontal longitudinal braces are perpendicular to the underground continuous walls, the projection of the horizontal longitudinal braces in the vertical direction overlaps the projection of the second servo area in the vertical direction, and the third servo area is located between two adjacent second servo areas;

[0009] A plurality of servo jacks are evenly spaced in the servo section and are arranged between the underground continuous wall and the purlin. The servo jacks are configured to provide support force for the underground continuous wall. The support force provided by the servo jacks located in the first servo area is configured to gradually decrease in the direction from approaching the second servo area to away from the second servo area, and in the direction from the second servo area to the first servo area, the support force of the first servo jack located in the first servo area is the same as the support force provided by the servo jack located in the second servo area, the support force provided by the plurality of servo jacks located in the second servo area is the same, the support force provided by the plurality of servo jacks located in the third servo area is the same, and the support force provided by the servo jacks located in the third servo area is greater than the support force provided by the servo jacks located in the second servo area.

[0010] Preferably, the supporting structure further comprises a hanger bar, one end of which is fixed to the perimeter purlin, and the other end of which is fixed to the underground continuous wall.

[0011] Preferably, the supporting structure also includes a first steel plate and a second steel plate, and the first steel plate and the second steel plate are both arranged along the length direction of the purlin. One side of the first steel plate can fit multiple servo jacks, and the other side is connected to the underground continuous wall. One side of the second steel plate can fit multiple servo jacks, and the other side is connected to the purlin.

[0012] Preferably, the first steel plate includes a first plate and a plurality of first plug-in parts arranged at intervals, the first plate is arranged along the length direction of the purlin, one end of the plurality of first plug-in parts is connected to the first plate, and the other end can extend into the interior of the underground continuous wall, the second steel plate includes a second plate and a plurality of second plug-in parts arranged at intervals, the second plate is arranged along the length direction of the purlin, one end of the plurality of second plug-in parts is connected to the second plate, and the other end can extend into the interior of the purlin.

[0013] Preferably, a safety pier is provided between two adjacent servo jacks, the safety pier and the surrounding purlin are integrally formed, and two ends of each safety pier are respectively attached to the first plate and the second plate.

[0014] Preferably, the local servo system of the foundation pit concrete support structure further includes a control device, and the plurality of servo jacks are all connected to and controlled by the control device.

[0015] Preferably, the supporting structure further comprises a plurality of horizontal diagonal braces, one end of each of the horizontal diagonal braces is fixed to the horizontal longitudinal brace, and the other end is fixed to the surrounding purlin.

[0016] Preferably, a reinforcement is further included, and the reinforcement is arranged in the servo section and inside the purlin.

[0017] Preferably, the local servo system of the foundation pit concrete support structure further includes an automatic compensation device, which is arranged on the servo jack and controlled by the control device.

[0018] Another object of the present invention is to provide a construction method for a local servo system of a foundation pit concrete support structure, which can coordinate the servo section and the non-servo section, give full play to the overall bearing performance, and effectively control the deformation of the underground continuous wall.

[0019] To achieve this object, the present invention adopts the following technical solutions:

[0020] The construction method of the local servo system of the foundation pit concrete support structure is applied to the above-mentioned local servo system of the foundation pit concrete support structure, and comprises the following steps:

[0021] S1. Cast underground continuous wall;

[0022] S2. Excavate the foundation pit between the newly cast underground diaphragm walls according to the design drawings;

[0023] S3. Cast horizontal longitudinal braces and perimeter purlins between the newly cast underground diaphragm walls;

[0024] S4. Install the servo jack into place;

[0025] S5, servo jack for pre-grading support;

[0026] S6, the servo jacks perform step-by-step loading support, and the support force provided by the servo jacks located in the first servo area is adjusted to gradually decrease from close to the second servo area to far away from the second servo area, and the support force of the servo jack closest to the second servo area reaches F1, the support force of the servo jacks located in the second servo area reaches F1, and the support force of the servo jacks located in the third servo area reaches F2, where F2>F1;

[0027] Repeat steps S2 to S6 until the foundation pit is excavated to the required depth.

[0028] Beneficial effects: The present invention provides a local servo system for a foundation pit concrete support structure, which has a large bearing capacity and can meet the deformation control requirements of relatively deep and large foundation pits, and is used to support underground continuous walls. The underground continuous walls are arranged on the side walls on opposite sides of the foundation pit and extend along the length direction. A servo section and two non-servo sections are arranged at the same height. The servo section is arranged between the two non-servo sections. The servo section includes two first servo areas, several second servo areas and several third servo areas. The two first servo areas are located at the outermost ends of the servo section. Each first servo area is connected to a non-servo section one by one. The second servo area and the third servo area are located between the two first servo areas. The local servo system for the foundation pit concrete support structure includes a support structure and multiple servo jacks. The support structure includes a purlin and multiple horizontal longitudinal braces arranged at intervals. The horizontal longitudinal braces are connected to the underground continuous walls on both sides through the purlin. The servo jacks are arranged in the servo area and between the purlin and the underground continuous wall, and can evenly distribute the supporting force through the purlin. The support force is evenly transferred to the horizontal longitudinal support, which is arranged perpendicular to the underground continuous wall and can effectively support the underground continuous wall. Furthermore, the projection of the horizontal longitudinal support in the vertical direction overlaps with the projection of the second servo area in the vertical direction. The third servo area is located between the two adjacent second servo areas. The first servo area is the transition area between the servo section and the non-servo section. The supporting force provided by the servo jack located in the first servo area gradually decreases in the direction from approaching the second servo area to away from the second servo area, and the supporting force of the servo jack closest to the second servo area is equal to the supporting force provided by the servo jack located in the second servo area, so as to evenly transition the forces acting on the servo section and the non-servo section and coordinate the deformation of the servo section and the non-servo section. Since the second servo section can directly receive the supporting force of the horizontal longitudinal support, the third servo section cannot directly receive the supporting force of the horizontal longitudinal support. The supporting force provided by the servo jack located in the third servo area is greater than the supporting force provided by the servo jack located in the second servo area to balance the supporting effect.

[0029] The present invention also provides a construction method of a local servo system for a foundation pit concrete support structure, which is completed by using the above-mentioned local servo system for the foundation pit concrete support structure. After pouring underground continuous walls of a certain height on opposite sides, the earth between the underground continuous walls is excavated to form a foundation pit. Furthermore, a template for pouring horizontal longitudinal braces and surrounding purlins is set between the newly poured underground continuous walls, and the horizontal longitudinal braces and surrounding purlins are formed in one piece. The underground continuous wall is divided into a servo section and a non-servo section. The servo section is divided into a first servo area, a second servo area and a third servo area according to the horizontal longitudinal braces. The servo jacks are arranged at intervals between the underground continuous wall and the purlin, and are located in the servo section. Pre-graded support is performed before the strength of the horizontal longitudinal bracing and the purlin meets the standard, so that the front of the servo jack can press the purlin tightly, and the rear of the servo jack can press the underground continuous wall tightly. After the strength of the horizontal longitudinal bracing and the purlin meets the standard, the servo jacks located in different areas are loaded with different supporting forces step by step. The above steps are repeated continuously until the foundation pit is excavated to the designed depth. This can coordinate the deformation of the servo section and the non-servo section, give full play to the overall bearing performance, and effectively control the deformation of the underground continuous wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a partial top view of a local servo system for a foundation pit concrete support structure provided by the first embodiment of the present invention;

[0031] Figure 2 This is a partial front view of a local servo system for a foundation pit concrete support structure provided by the first embodiment of the present invention;

[0032] Figure 3 is a cross-sectional schematic diagram of a local servo system of a foundation pit concrete support structure provided by the first embodiment of the present invention;

[0033] Figure 4 is a schematic structural diagram of a first steel plate provided in Example 1 of the present invention;

[0034] Figure 5 It is a schematic structural diagram of the second steel plate provided in Example 1 of the present invention.

[0035] In the picture:

[0036] 1. Underground continuous wall; 11. Servo section; 111. First servo area; 112. Second servo area; 113. Third servo area; 12. Non-servo section;

[0037] 21. Servo jack; 22. Purlin; 23. Horizontal longitudinal brace; 24. Horizontal diagonal brace; 25. First steel plate; 251. First plug-in portion; 252. First plate; 26. Second steel plate; 261. Second plug-in portion; 262. Second plate; 27. First support member; 28. Second support member; 29. ​​Steel casing; 2a. Safety pier; 2b. Reinforcement member; 2c. Hanger bar. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0039] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0040] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0041] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0042] Example 1

[0043] This embodiment provides a local servo system for a foundation pit concrete support structure, used to support an underground continuous wall 1, wherein the underground continuous wall 1 is arranged on the sidewalls of opposite sides of the foundation pit and extends along the length. Preferably, the sidewalls of existing foundation pits are all vertically arranged, and the underground continuous wall 1 is also vertically arranged. This embodiment scientifically divides the underground continuous wall 1 into a servo section 11 and a non-servo section 12, reducing costs. The servo section 11 is further subdivided to provide different support forces for different areas, and the servo section 11 and the non-servo section 12 are coordinated to effectively control the deformation of the underground continuous wall 1. The local servo system for the foundation pit concrete support structure includes a support structure, a plurality of servo jacks 21, and a control device. The support structure can support the underground continuous wall 1 and reduce its deformation. The plurality of servo jacks 21 are connected to the control device and are used to provide support force to control the deformation of the underground continuous wall 1 and improve the stability of the foundation pit. The control device can flexibly adjust the support force of the servo jacks 21 according to deformation control and environmental protection requirements at different locations of the underground continuous wall 1, effectively controlling the deformation of the underground continuous wall 1.

[0044] Specifically, if Figure 1 and Figure 2As shown, the supporting structure includes a purlin 22 and a plurality of horizontal longitudinal braces 23 arranged at intervals. The horizontal longitudinal braces 23 are connected to the underground continuous walls 1 on both sides through the purlin 22, and the horizontal longitudinal braces 23 are arranged perpendicular to the underground continuous walls 1, that is, the two ends of the horizontal longitudinal braces 23 are abutted between the underground continuous walls 1 on both sides through the purlin 22. In this embodiment, the purlin 22 is a rectangular parallelepiped horizontally arranged on the underground continuous wall 1. In other embodiments, the purlin 22 can also be other irregular shapes, which are not limited here. Furthermore, in this embodiment, the underground continuous wall 1 is configured as a servo section 11 and two non-servo sections 12 at the same height. The servo section 11 is configured between the two non-servo sections 12. Preferably, the servo section 11 is the middle portion of the underground continuous wall 1 in the horizontal direction. Specifically, the servo section 11 includes two first servo areas 111, a plurality of second servo areas 112, and a plurality of third servo areas 113. The two first servo areas 111 are located at the outermost ends of the servo section 11. Each first servo area 111 is connected to a non-servo section 12 in a one-to-one correspondence. The second servo area 112 and the third servo area 113 are located between the two first servo areas 111, and the projection of the second servo area 112 in the vertical direction can overlap with the projection of the horizontal longitudinal support 23 in the vertical direction. The third servo area 113 is located between two adjacent second servo areas 112. It should be noted that the first servo zone 111 is the transition zone between the servo segment 11 and the non-servo segment 12, the second servo zone 112 is the zone that can be directly supported by the horizontal longitudinal brace 23, and the third servo zone 113 is the zone that cannot be directly supported by the horizontal longitudinal brace 23. The above conditions are used to scientifically divide the underground continuous wall 1 into areas, which is convenient for coordinating the deformation of the servo segment 11 and the non-servo segment 12 and effectively controlling the deformation of the underground continuous wall 1.

[0045] The surrounding purlins 22 and the horizontal longitudinal braces 23 in this embodiment are both made of reinforced concrete, the internal steel bars are all interwoven in a grid shape, and are an integrally cast structure.

[0046] Alternatively, as Figure 3 As shown, the underground continuous wall 1 and the purlin 22 are connected by a hanger 2c, one end of the hanger 2c is fixed to the purlin 22, and the other end is fixed to the underground continuous wall 1. Specifically, one end of the hanger 2c is welded to the steel structure in the purlin 22, and the other end is welded to the steel structure inside the underground continuous wall 1 to improve the connection strength.

[0047] like Figure 1-Figure 3As shown, in this embodiment, multiple servo jacks 21 are arranged at intervals in the servo section 11 along the length of the purlin 22 and are located between the underground continuous wall 1 and the purlin 22. The servo jacks 21 can apply a force to the purlin 22, thereby providing a supporting force for the side of the underground continuous wall 1 facing the servo jacks 21, while simultaneously providing a reaction force on the side of the underground continuous wall 1 away from the servo jacks 21 to control the deformation of the underground continuous wall 1. Preferably, the force provided by the servo jacks 21 is perpendicular to the length of the underground continuous wall 1 to improve the effectiveness of controlling its deformation. Moreover, by arranging the servo jacks 21 between the underground continuous wall 1 and the purlin 22, the supporting force provided by the servo jacks 21 can be evenly transmitted to various areas of the support structure through the purlin 22.

[0048] Optionally, the distance between two adjacent servo jacks 21 in this embodiment is 3 m, and may be other values ​​in other embodiments, which is not limited here.

[0049] Furthermore, after being formally put into use, for example, the surrounding pressure of the servo area is calculated as 600 kN / m. Since the supporting force and number of the servo jacks 21 should be balanced with the surrounding pressure of the servo area, in this embodiment, the distance between two adjacent servo jacks 21 is set to 3m, and the supporting force provided by the servo jacks 21 located in the first servo area 111 is configured to gradually decrease from the direction close to the second servo area 112 to the direction away from the second servo area 112, and in the direction from the second servo area 112 to the first servo area 111, the supporting force of the first servo jack 21 located in the first servo area 111 is equal to that of the servo jack 21 located in the second servo area 112. The servo jacks 21 in the second servo zone 112 provide the same supporting force of 200t each, which evenly transitions the forces acting on the servo section 11 and the non-servo section 12, coordinates the deformation of the servo section 11 and the non-servo section 12, effectively prevents the purlin 22 of the non-servo section 12 from being excessively separated from the underground continuous wall 1, and ensures the integrity of the support structure. Furthermore, because the second servo zone 112 can directly receive the supporting force of the horizontal longitudinal bracing 23, the deformation control effect is better than that of the third servo zone 113. Therefore, the servo jacks 21 in the third servo zone 113 provide a supporting force of 300t each. In other embodiments, the spacing between two adjacent servo jacks 21 and their supporting force can be adjusted by the confining pressure of the servo zone, which is not specifically limited here.

[0050] Preferably, if Figure 3As shown, the supporting structure also includes a first steel plate 25 and a second steel plate 26. The first steel plate 25 and the second steel plate 26 are both arranged along the length direction of the purlin 22. One side of the first steel plate 25 can fit a number of servo jacks 21, and the other side is connected to the underground continuous wall 1. One side of the second steel plate 26 can fit a number of servo jacks 21, and the other side is connected to the purlin 22. By arranging the first steel plate 25 and the second steel plate 26, the force provided by the servo jacks 21 can be evenly transmitted to the underground continuous wall 1 and the purlin 22, and the local pressure on the underground continuous wall 1 and the purlin 22 can be reduced to prevent them from being damaged.

[0051] More preferably, if Figure 4 As shown, the first steel plate 25 includes a first plate 252 and a plurality of first plug-in portions 251 arranged at intervals. The first plate 252 is arranged along the length direction of the purlin 22. One side of the first plate 252 can be attached to the plurality of servo jacks 21. The plurality of first plug-in portions 251 are connected to the other side of the first plate 252. At the same time, the plurality of first plug-in portions 251 can extend into the interior of the underground continuous wall 1 to achieve the connection between the first steel plate 25 and the underground continuous wall 1, thereby improving the stability. Similarly, as shown in FIG. Figure 5 As shown, the second steel plate 26 includes a second plate 262 and a plurality of second plug-in portions 261 arranged at intervals. The second plate 262 is arranged along the length direction of the purlin 22. One side of the second plate 262 can be fitted with the plurality of servo jacks 21. The plurality of second plug-in portions 261 are connected to the other side of the second plate 262. At the same time, the plurality of second plug-in portions 261 can extend into the purlin 22 to achieve the connection between the second steel plate 26 and the purlin 22, thereby improving the stability.

[0052] Furthermore, in order to realize the support of multiple servo jacks 21, as shown in FIG. Figure 3 As shown, the support structure provided by this embodiment further includes a first support member 27 and a second support member 28. The upper end surfaces of the first support member 27 and the second support member 28 are flush. Specifically, the first support member 27 is arranged along the length direction of the purlin 22 and extends in a direction perpendicular to the underground continuous wall 1. One end of the first support member 27 is fixed to the underground continuous wall 1. The second support member 28 is arranged along the length direction of the purlin 22. One end of the second support member 28 is fixed to the second plate 262 / purlin 22, and the other end extends in a direction perpendicular to the underground continuous wall 1. A plurality of servo jacks 21 can be placed on the upper end surfaces of the first support member 27 and the second support member 28, as shown in FIG. Figure 3 As shown, the second support member 28 in this embodiment is fixed to the second plate 262. Optionally, the cross-sections of the first support member 27 and the second support member 28 can be right-angled trapezoids or right-angled triangles to improve the stability of the support.

[0053] Preferably, continue to see Figure 2 and Figure 3Each servo jack 21 is arranged in a steel casing 29. The steel casing 29 includes a bottom plate, two side plates and a cover plate. The two side plates are arranged relatively on the bottom plate, and the cover plate is connected to the two side plates. A fixing part is provided on the bottom plate. The shape of the fixing part matches the outer contour of the servo jack 21 to prevent the servo jack 21 from shifting. The bottom plate of the steel casing 29 can be tightly pressed against the upper end surfaces of the first support member 27 and the second support member 28, and can ensure that the front of the servo jack 21 abuts against the second plate 262 and the rear abuts against the first plate 252. While forming a protective layer for the servo jack 21, it does not hinder the supporting function of the servo jack 21.

[0054] The supporting structure in this embodiment also includes a plurality of safety piers 2a, such as Figure 2 As shown, the safety pier 2a is arranged between two adjacent servo jacks 21. The safety pier 2a and the purlin 22 are an integrally cast structure, and the two ends of each safety pier 2a are respectively attached to the first plate 252 and the second plate 262. When the servo jack 21 malfunctions or fails, the safety of the supporting structure can be guaranteed.

[0055] Preferably, the support structure also includes a plurality of reinforcement members 2b, which are arranged inside the purlin 22 of the servo section 11 to ensure the bearing capacity and stability of the purlin 22 when the plurality of servo jacks 21 apply supporting force. The reinforcement members 2b are stiffening plates or stiffening ribs and are formed by pouring concrete.

[0056] Furthermore, the supporting structure provided in this embodiment also includes a plurality of horizontal diagonal braces 24. Preferably, the plurality of horizontal diagonal braces 24 are perpendicular to the underground continuous wall 1 and are located at the same height as the plurality of horizontal longitudinal braces 23. One end of the plurality of horizontal diagonal braces 24 is fixed to the horizontal longitudinal brace 23, and the other end is fixed to the purlin 22 to form a grid structure with the plurality of horizontal longitudinal braces 23 to improve the stability of the supporting structure. Further optionally, the plurality of horizontal diagonal braces 24 in this embodiment are evenly arranged on the plurality of horizontal longitudinal braces 23 to evenly support the stability of different areas of the structure in the horizontal direction.

[0057] The horizontal diagonal braces 24 in this embodiment are made of reinforced concrete, the internal steel bars are all interwoven in a grid pattern, and are integrally cast together with the purlins 22 and the horizontal longitudinal braces 23 .

[0058] Optionally, an automatic compensation device is provided on the servo jack 21, which is controlled by the control device. When it is detected that the force applied by the servo jack 21 deviates from the set value, it can automatically adjust within the range of ±10t to ensure effective support of the support structure.

[0059] Example 2

[0060] This embodiment provides a construction method for a local servo system of a foundation pit concrete support structure, which is applied to the above-mentioned local servo system of the foundation pit concrete support structure. The construction method for the local servo system of the foundation pit concrete support structure includes the following steps:

[0061] S1, pouring underground continuous wall 1;

[0062] S2. Excavate a foundation pit between the newly cast underground continuous walls 1 according to the design drawings;

[0063] S3, pouring horizontal longitudinal braces 23 and purlins 22 between the newly poured underground continuous walls 1;

[0064] S4, the servo jack 21 is installed in place;

[0065] S5, servo jack 21 performs pre-grading support;

[0066] S6. The servo jacks 21 are loaded and supported step by step, and the supporting force provided by the servo jacks 21 located in the first servo area 111 is adjusted to gradually decrease from close to the second servo area 112 to far away from the second servo area 112, and the supporting force of the servo jacks 21 closest to the second servo area 112 reaches F1, the supporting force of the servo jacks 21 located in the second servo area 112 reaches F1, and the supporting force of the servo jacks 21 located in the third servo area 113 reaches F2, where F2>F1;

[0067] Repeat steps S2 to S6 until the foundation pit is excavated to the required depth.

[0068] After pouring underground continuous walls 1 of a certain height on opposite sides, the earth between the underground continuous walls 1 on both sides is excavated to form a foundation pit. Furthermore, a template for pouring horizontal longitudinal braces 23 and purlins 22 is set between the newly poured underground continuous walls 1 on both sides, and the horizontal longitudinal braces 23 and purlins 22 are formed as one piece. The underground continuous wall 1 is divided into a servo section 11 and a non-servo section 12. The servo section 11 is divided into a first servo area 111, a second servo area 112 and a third servo area 113 according to the horizontal longitudinal braces 23. A plurality of servo jacks 21 are arranged at intervals between the underground continuous wall 1 and the purlin 22, and are located in the servo section 11. Pre-graded support is performed before the strength of the horizontal longitudinal braces 23 and the purlin 22 meets the standard. The front part of the servo jack 21 can press against the purlin 22, and the rear part of the servo jack 21 can press against the underground continuous wall 1. After the strength of the horizontal longitudinal brace 23 and the purlin 22 reaches the standard, the servo jacks 21 located in different areas are loaded step by step to the preset values ​​F1 and F2. In this embodiment, the preset F1 is set to 200t and F2 is set to 300t. In other embodiments, the distance between two adjacent servo jacks 21 and F1 and F2 can be adjusted by the confining pressure of the servo area. No specific limitation is made here. The construction method of the local servo system of the foundation pit concrete support structure can coordinate the deformation of the servo section 11 and the non-servo section 12, give full play to the overall bearing performance, and effectively control the deformation of the underground continuous wall 1.

[0069] Specifically, S1 includes:

[0070] S1.1. Construct underground diaphragm wall 1 according to the design drawing;

[0071] In S2, the soil between the newly cast underground continuous walls 1 is excavated to form a foundation pit.

[0072] Specifically, S2 includes:

[0073] S2.1. After the foundation pit is excavated to a preset support depth, the first support member 27 and the first steel plate 25 are fixed at the preset support depth of the underground continuous wall 1.

[0074] Specifically, the first support member 27 is arranged horizontally, and one end thereof is fixed on the underground continuous wall 1. The first steel plate 25 is higher than the first support member 27. The multiple first plug-in parts 251 in the first steel plate 25 are inserted into the underground continuous wall 1, and the first plate 252 is arranged vertically.

[0075] Specifically, S3 includes:

[0076] S3.1. Install and set up the formwork for casting the perimeter purlins 22, horizontal longitudinal braces 23, horizontal diagonal braces 24, and safety piers 2a between the newly cast underground diaphragm walls 1;

[0077] S3.2. Connect one end of the hanger bar 2c to the underground continuous wall 1, and connect the other end of the hanger bar 2c to the purlin 22;

[0078] S3.3. Fix the second steel plate 26 on the purlin 22;

[0079] Specifically, the support formwork is set up, the purlin 22, horizontal longitudinal brace 23, horizontal diagonal brace 24 and safety pier 2a are integrally formed, one end of the hanger 2c is welded to the steel structure in the underground continuous wall 1, and the other end of the hanger 2c is welded to the steel structure in the purlin 22 to improve the connection strength. Furthermore, one end of the hanger 2c connected to the underground continuous wall 1 is higher than the first steel plate 25, and the multiple second plug-in parts 261 in the second steel plate 26 are inserted into the purlin 22, and the second plate 262 is arranged vertically, and the first plate 252 and the second plate 262 are opposite. When the second support member 28 is fixed to the second steel plate 26, one end of the second support member 28 needs to be horizontally welded to the second steel plate 26 in the horizontal direction before installing the second steel plate 26. When the second support member 28 is fixed to the purlin 22 in the horizontal direction, the second steel plate 26 and the second support member 28 can be installed and fixed at the same time, and the second steel plate 26 is located above the second support member 28.

[0080] Specifically, S4 includes:

[0081] S4.1, hoisting multiple servo jacks 21;

[0082] Specifically, the servo jack 21 is placed in the reserved gap between the purlin 22 and the underground continuous wall 1, and is located in the servo section 11. For example, in this embodiment, the distance between two adjacent servo jacks 21 is 3m, and each servo jack 21 is respectively arranged between two adjacent safety piers 2a, and the two ends of the servo jack 21 can respectively abut the first steel plate 25 and the second steel plate 26.

[0083] Specifically, when the strength of the safety pier 2a, the horizontal longitudinal brace 23, the horizontal diagonal brace 24 and the purlin 22 reaches 80%, pre-stage support is performed, and the safety factor of the servo jack 21 is set to 1.25. The support force of each servo jack 21 is increased step by step through the control device, and the loading increment of each level is set to 20t. The support force of the servo jack 21 located in the first servo area 111 is configured to gradually decrease from close to the second servo area 112 to away from the second servo area 112, and the support force closest to the second servo area 112 is gradually reduced. The supporting force of the servo jack 21 in area 112 does not exceed 100t, the supporting force of the servo jack 21 located in the second servo area 112 is configured to be no more than 100t, and the supporting force of the servo jack 21 located in the third servo area 113 is configured to be no more than 200t, so that the front of the servo jack 21 is tightly pressed against the second steel plate 26, and the rear of the servo jack 21 is tightly fitted against the first steel plate 25 without a gap. For example, F1 in this embodiment is set to 200t, and F2 is set to 300t.

[0084] S6 specifically involves performing graded support after the strength of the safety pier 2a, horizontal longitudinal brace 23, horizontal diagonal brace 24 and purlin 22 meets the standards. The safety factor of the servo jack 21 is set to 1.25, and the supporting force of each servo jack 21 is gradually increased through the control device. The loading increment of each level is set to 20t. The supporting force of the servo jack 21 located in the first servo area 111 is configured to gradually decrease from close to the second servo area 112 to far away from the second servo area 112, and the supporting force of the servo jack 21 closest to the second servo area 112 reaches 200t, the supporting force of the servo jack 21 located in the second servo area 112 reaches 200t, and the supporting force of the servo jack 21 located in the third servo area 113 reaches 300t, thereby controlling the deformation of the underground continuous wall 1 during the subsequent construction process of the foundation pit.

[0085] During processes S5 and S6, since the servo jack 21 applies a supporting force to the first steel plate 25 and the second steel plate 26, the gap between the first steel plate 25 and the second steel plate 26 increases. If a gap appears between the safety pier 2a and the first and second steel plates 25 and 26, concrete slurry is used to pour it to ensure that the safety pier 2a can be tightly abutted between the first and second steel plates 25 and 26.

[0086] Continue to excavate the earthwork below, and repeat steps S2 to S6 to construct and support each concrete support servo system in the foundation pit until the foundation pit is excavated to the designed depth.

[0087] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. A person skilled in the art would be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A local servo system for a foundation pit concrete support structure, used for supporting an underground continuous wall (1), wherein the underground continuous wall (1) is arranged on the side walls of opposite sides of the foundation pit and extends along the length direction, wherein the underground continuous wall (1) is provided with a servo section (11) and two non-servo sections (12) at the same height, wherein the servo section (11) is arranged between the two non-servo sections (12), wherein the servo section (11) includes two first servo areas (111), a plurality of second servo areas (112) and a plurality of third servo areas (113), wherein the two first servo areas (111) are located at the outermost ends of the servo section (11), wherein each first servo area (111) is connected to one of the non-servo sections (12) in a one-to-one correspondence, and wherein the second servo area (112) and the third servo area (113) are located between the two first servo areas (111), and wherein: include: A support structure, the support structure comprising a purlin (22) and a plurality of horizontal longitudinal braces (23) arranged at intervals, the horizontal longitudinal braces (23) being connected to the underground continuous walls (1) on both sides via the purlin (22), the horizontal longitudinal braces (23) being perpendicular to the underground continuous walls (1), the projection of the second servo area (112) in the vertical direction being able to overlap with the projection of the horizontal longitudinal brace (23) in the vertical direction, and the third servo area (113) being located between two adjacent second servo areas (112); A plurality of servo jacks (21) are evenly spaced apart in the servo section (11) and arranged between the underground continuous wall (1) and the purlin (22). The servo jacks (21) are configured to provide a supporting force for the underground continuous wall (1). The supporting force provided by the servo jacks (21) located in the first servo area (111) is configured to gradually decrease in a direction from approaching the second servo area (112) to away from the second servo area (112), and in a direction from the second servo area (112) to the first servo area (111), The supporting force provided by the first servo jack (21) located in the first servo zone (111) is the same as the supporting force provided by the servo jack (21) located in the second servo zone (112), the supporting force provided by multiple servo jacks (21) located in the second servo zone (112) is the same, the supporting force provided by multiple servo jacks (21) located in the third servo zone (113) is the same, and the supporting force provided by the servo jack (21) located in the third servo zone (113) is greater than the supporting force provided by the servo jack (21) located in the second servo zone (112).

2. The local servo system for foundation pit concrete support structure according to claim 1, characterized in that: The supporting structure further comprises a hanger bar (2c), one end of the hanger bar (2c) being fixed to the surrounding purlin (22) and the other end being fixed to the underground continuous wall (1).

3. The local servo system for foundation pit concrete support structure according to claim 2, characterized in that: The supporting structure further comprises a first steel plate (25) and a second steel plate (26), wherein the first steel plate (25) and the second steel plate (26) are both arranged along the length direction of the purlin (22), one side of the first steel plate (25) can be fitted with a plurality of the servo jacks (21), and the other side is connected to the underground continuous wall (1), and one side of the second steel plate (26) can be fitted with a plurality of the servo jacks (21), and the other side is connected to the purlin (22).

4. The local servo system for foundation pit concrete support structure according to claim 3, characterized in that: The first steel plate (25) includes a first plate (252) and a plurality of first plug-in parts (251) arranged at intervals, the first plate (252) is arranged along the length direction of the purlin (22), one end of the plurality of first plug-in parts (251) is connected to the first plate (252), and the other end can extend into the interior of the underground continuous wall (1), the second steel plate (26) includes a second plate (262) and a plurality of second plug-in parts (261) arranged at intervals, the second plate (262) is arranged along the length direction of the purlin (22), one end of the plurality of second plug-in parts (261) is connected to the second plate (262), and the other end can extend into the interior of the purlin (22).

5. The local servo system for foundation pit concrete support structure according to claim 4, characterized in that: A safety pier (2a) is provided between two adjacent servo jacks (21); the safety pier (2a) and the surrounding purlin (22) are integrally formed, and two ends of each safety pier (2a) are respectively attached to the first plate (252) and the second plate (262).

6. The local servo system for foundation pit concrete support structure according to any one of claims 1 to 5, characterized in that: The local servo system of the foundation pit concrete support structure also includes a control device, and the plurality of servo jacks (21) are all connected to the control device and controlled by the control device.

7. The local servo system for foundation pit concrete support structure according to any one of claims 1 to 5, characterized in that: The supporting structure further comprises a plurality of horizontal diagonal braces (24), one end of each of the horizontal diagonal braces (24) is fixed to the horizontal longitudinal brace (23), and the other end is fixed to the surrounding purlin (22).

8. The local servo system for foundation pit concrete support structure according to any one of claims 1 to 5, characterized in that: It also includes a reinforcement member (2b), which is arranged on the servo section (11) and inside the purlin (22).

9. The local servo system for foundation pit concrete support structure according to claim 6, characterized in that: The local servo system of the foundation pit concrete support structure also includes an automatic compensation device, which is arranged on each of the servo jacks (21) and is controlled by the control device.

10. A construction method for a local servo system of a foundation pit concrete support structure, applied to the local servo system of a foundation pit concrete support structure according to any one of claims 1 to 9, characterized in that: The steps include: S1. Casting of underground continuous wall (1); S2. Excavate a foundation pit between the newly cast underground continuous walls (1) according to the design drawings; S3, pouring horizontal longitudinal braces (23) and purlins (22) between the newly poured underground continuous walls (1); S4, the servo jack (21) is installed in place; S5, servo jack (21) performs pre-grading support; S6, the servo jack (21) performs step-by-step loading support, and the supporting force provided by the servo jack (21) located in the first servo area (111) is adjusted to gradually decrease from close to the second servo area (112) to far away from the second servo area (112), and the supporting force of the servo jack (21) closest to the second servo area (112) reaches F1, the supporting force of the servo jack (21) located in the second servo area (112) reaches F1, and the supporting force of the servo jack (21) located in the third servo area (113) reaches F2, and F2>F1; Repeat steps S2 to S6 until the foundation pit is excavated to the required depth.

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