Shallow foundation pit partition active regulation supporting structure and construction method

Abstract

This invention discloses a zoned active control support structure and construction method for shallow foundation pits, belonging to the field of foundation pit construction technology. It includes a retaining structure, an internal support structure, a monitoring system, and an inclinometer connected to the existing underground structure. A grouting device is installed on the top of the retaining structure facing the existing underground structure. The retaining structure is divided into active zones facing the existing underground structure and underground continuous walls facing other areas. The active zones are further divided into multiple adjacent zones. The support structure includes several horizontal support systems. At the corresponding positions of the active zones, each horizontal support system includes multiple servo internal supports positioned between the underground continuous walls and the active zones. The inclinometer monitors soil deformation in real time, and then controls the corresponding servo internal supports to output displacement, thereby moving the active zones forward and actively controlling soil deformation.

Description

Technical Field

[0001] This invention belongs to the field of foundation pit construction technology, specifically relating to a shallow foundation pit zoned active control support structure and construction method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] As a crucial link in underground space development, the safety of the support structure in foundation pit engineering directly affects the construction progress and the stability of surrounding buildings and structures. In complex urban geological environments, traditional support systems often face the following technical bottlenecks: First, homogeneous support schemes are difficult to adapt to the differences in soil parameters in different areas, leading to local over-support or under-support; second, conventional monitoring methods rely on manual data collection, making it difficult to achieve real-time capture of sudden displacements; third, traditional support schemes are passive support methods, unable to actively control the displacement of adjacent buildings. Summary of the Invention

[0004] To address the aforementioned issues, this invention, based on the concept of differentiated support, innovatively proposes a zoned active control support structure and construction method for shallow foundation pits. By dividing the retaining structure facing the existing underground structure into independent grid units and configuring adjustable servo internal supports, a support system with regional self-adaptive capabilities is formed. This enables precise deformation control of areas with different risk levels, preventing local over-support or under-support. A monitoring system monitors the construction process in real time, acquiring soil deformation data promptly and implementing dynamic adjustments based on feedback. An inclinometer monitors soil deformation in real time, then controls the corresponding servo internal support output displacement, thereby moving the active grid forward and actively controlling soil deformation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In the first aspect, a shallow foundation pit zone active control support structure is provided, including a retaining structure, a support structure is set inside the retaining structure, a monitoring system is also included, an inclinometer of the monitoring system is set between the retaining structure and the existing underground structure, and a grouting device is set on the top of the retaining structure facing the existing underground structure.

[0007] The enclosure structure is divided into active zones facing the existing underground structure and underground continuous walls facing other areas; the active zones are further divided into multiple adjacent zones.

[0008] The supporting structure includes several horizontal support systems. Each horizontal support system includes walers installed circumferentially along the inner wall of the enclosure structure and internal supports installed at the four corners of the diaphragm wall. The two ends of the internal supports are fixedly connected to the walers. It also includes servo internal supports that drive the movement of the grid. In the horizontal support system below the movable grid, the servo internal supports are replaced by internal supports, which act on the diaphragm wall through the walers.

[0009] Preferably, rubber sealing strips are fixedly installed on both sides of all sections; rubber sealing strips are also fixedly installed on the side where the diaphragm wall connects to the section; the rubber sealing strips are made of serrated structure and can interlock to enhance the water-stopping effect.

[0010] Preferably, the height of the movable grid is less than the height of the diaphragm wall. Several stainless steel ball bearings are installed at the bottom of the grid to reduce the friction between the movable grid and the bottom diaphragm wall, thereby facilitating the movement of the grid. Water baffles are installed on both the inner and outer sides of the bottom of the grid to prevent groundwater from seeping in and to prevent soil from entering and affecting the movement of the grid.

[0011] Preferably, the compartment is provided with a grouting pipe that extends directly to the bottom of the compartment, for injecting anti-seepage and leak-stopping materials during construction and for injecting concrete mortar after construction, so as to ensure the integrity and waterproof performance of the structure.

[0012] Preferably, the horizontal support system uses multiple columns to achieve vertical support, ensuring stress stability; the walers must not be set at the horizontal intersection of the activity zone and the underground continuous wall.

[0013] Preferably, the monitoring system also includes a servo-supported servo hydraulic cylinder group and a monitoring center; the monitoring center is wirelessly connected to the inclinometer and the servo-supported servo hydraulic cylinder group to achieve real-time connection and data interaction.

[0014] Preferably, the grouting device includes grouting machines with the same number of compartments. Each grouting machine is connected to multiple grout delivery pipes via a grout outlet pipe. The number of grout delivery pipes connected to each grouting machine is equal to the number of grouting pipes in each compartment.

[0015] Secondly, a construction method for the aforementioned shallow foundation pit zoned active control support structure is provided, with the specific steps as follows:

[0016] S1. Before construction, install the inclinometer and connect the monitoring center to the inclinometer.

[0017] S2. Excavate guide trenches and construct guide walls around the foundation pit. Excavate trenches in sections and cast diaphragm walls in place. When the construction reaches the movable grid position, first install rubber sealing strips on the steel cage of the diaphragm wall and hoist it into the trench section. Then pour the diaphragm wall. After the concrete has set, hoist the movable grid and complete the installation. Repeat the above procedures until the diaphragm wall construction of all trench sections is completed.

[0018] S3. After the maintenance is completed, the foundation pit is excavated to the specified depth and the first horizontal support system is installed; the current servo internal support is connected to the monitoring center; then the excavation continues to a deeper specified position, and the above steps are repeated to install the second horizontal support system until the last horizontal support system is completed.

[0019] S4. After the excavation and support of the foundation pit are completed, the inner wall water baffle is opened in an orderly manner, the residual water-absorbing resin sealing material is removed and the water baffle is reset; then concrete mortar is poured into the bottom of the active area to achieve a rigid connection between the area and the underground continuous wall; multiple areas are connected into a whole by steel structure to form a coordinated force system; finally, the supporting structure is removed in sequence.

[0020] Preferably, in S3, the monitoring system starts working when the foundation pit is excavated; as the excavation depth increases, the lateral earth pressure and the deformation of the surrounding soil gradually intensify; when the monitoring data of a certain inclinometer shows that the soil deformation exceeds the warning value, the calculation model in the monitoring center calculates the displacement that the corresponding grid needs to output, and then adjusts the corresponding servo internal support to push the corresponding grid forward in order to control the soil deformation;

[0021] During adjustment, water-absorbing resin-based sealing material is injected into the bottom of the active area through a grouting device to fill the gaps and prevent seepage.

[0022] Preferably, in the calculation model, the horizontal displacement u produced by a point (0, ξ, η) in the load on the sidewall of the existing underground structure near the ground pit on a point (x1, y1, z1) on the inclinometer is... x1 The displacement s of the active zone under the action of the servo internal support can be obtained through inclinometer monitoring. x0 The horizontal displacement s of the active area is obtained from the functional relationship. x0 The functional relationship is as follows:

[0023] ;

[0024] ;

[0025] In the formula: ;

[0026] λ For active control adjustment coefficients; iThis is the i-th layer of stratified soil; n The number of stratified soil layers; hi Let be the depth of the i-th layer of soil in the active area; a The width of the active area grid pair; ki Let be the subgrade coefficient of the i-th soil layer; vi Let be the Poisson's ratio of the i-th soil layer; Gi Let be the shear elastic modulus of the i-th soil layer; Let be the length of the infinitesimal element of the i-th soil layer along the y-axis. ξi Let y be the y-coordinate of a point in the i-th soil layer along the y-axis; dηi Let be the length of the infinitesimal element of the i-th soil layer along the z-axis. ηi Let be the z-axis coordinate of a point in the i-th soil layer along the z-axis direction.

[0027] Compared with the prior art, the advantages and positive effects of this invention are:

[0028] This invention divides the retaining structure facing the existing underground structure into independent grid units and configures them with adjustable servo internal supports to form a support system with regional self-adaptive capabilities, thereby achieving precise deformation control for areas with different risk levels. A monitoring system monitors the construction process in real time, promptly acquiring soil deformation data and dynamically adjusting based on feedback. An inclinometer monitors soil deformation in real time and then controls the corresponding servo internal support output displacement, thereby moving the active grid forward and actively controlling soil deformation. Specifically, this invention effectively solves the problem of insufficient adaptability of traditional support systems in complex engineering environments, significantly improving the safety and economy of foundation pit engineering. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is an overall schematic diagram of the support structure of Embodiment 1 or 2 of the present invention;

[0031] Figure 2 This is an overall schematic diagram of the enclosure structure of Embodiment 1 or 2 of the present invention;

[0032] Figure 3 This is a schematic diagram of the first, second, or third grid of Embodiment 1 or 2 of the present invention;

[0033] Figure 4 This is a schematic diagram of the connection between the rubber sealing strips in Embodiment 1 or 2 of the present invention;

[0034] Figure 5 This is a schematic diagram of the support structure of Embodiment 1 or 2 of the present invention;

[0035] Figure 6 This is a schematic diagram of the monitoring system of Embodiment 1 or 2 of the present invention;

[0036] Figure 7 This is a schematic diagram of the grouting device according to Embodiment 1 or 2 of the present invention;

[0037] Figure 8 This is a front view of the calculation model of embodiment 1 or 2 of the present invention;

[0038] Figure 9 This is a top view of the calculation model of embodiment 1 or 2 of the present invention;

[0039] In the picture:

[0040] 1. Enclosure structure; 11. Diaphragm wall; 12. Active zone; 121. First zone; 122. Second zone; 123. Third zone; 124. Rubber sealing strip; 125. Stainless steel ball bearing; 126. Grouting pipe; 127. Water baffle; 128. Waler; 2. Support structure; 21. Servo internal support; 211. Servo hydraulic cylinder group; 212. Support rod; 22. Internal support; 23. Column; 3. Existing underground structure; 4. Monitoring system; 41. Inclinometer; 42. Monitoring center; 5. Grouting device; 51. Grouting machine; 52. Grout delivery pipe; 6. Stratum; 61. First zone; 62. Second zone; 63. Excavation pit area. Detailed Implementation

[0041] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0042] The present invention will now be described in detail with reference to the accompanying drawings.

[0043] Example 1

[0044] This embodiment discloses a shallow foundation pit zoned active control support structure, such as... Figure 1 As shown, it includes a square enclosure structure 1, a support structure 2 is installed inside the enclosure structure 1, several inclinometers 41 of the monitoring system 4 are installed between the enclosure structure 1 and the existing underground structure 3, and a grouting device 5 is installed on the top of the side of the enclosure structure 1 facing the existing underground structure 3.

[0045] The enclosure structure 1 is divided into two parts according to the area: a diaphragm wall 11 and an active zone 12. For example... Figure 1 , Figure 2As shown, the retaining structure 1 is set in the stratum 6, dividing the stratum 6 into three regions. The region directly opposite the existing underground structure 3 is the second region 62, and the region enclosed by the retaining structure 1 is the foundation pit region 63. The remaining regions are the first region 61. The soil deformation in the first region 61 is controlled by the diaphragm wall 11, which is cast-in-place. The soil deformation in the second region 62 is controlled by the movable grid 12, which is constructed using a prefabricated method and assembled in a factory to improve construction efficiency and quality. To precisely control the soil deformation in the second region 62, the movable grid 12 is divided into multiple adjacent grids. In this embodiment, the movable grid 12 is divided into three adjacent grids: the first grid 121, the second grid 122, and the third grid 123. It can be understood that the number of movable grids 12 can be more depending on the actual situation. At least one inclinometer 41 is installed between each movable grid 12 and the existing underground structure 3.

[0046] like Figure 2 , Figure 3 As shown, the active area 12 includes three sections: the first section 121, the second section 122, and the third section 123. Rubber sealing strips 124 are fixedly installed on both sides of each section; as shown... Figure 2 As shown, rubber sealing strips 124 are also fixedly installed on the side of the diaphragm wall 11 where it connects to the first grid 121 or the third grid 123. For example... Figure 4 As shown, the rubber sealing strip 124 is constructed with a serrated structure, which allows the rubber sealing strips 124 to interlock with each other, thereby enhancing the water-stopping effect.

[0047] like Figure 2 As shown, the height of the active zone 12 is less than the height of the diaphragm wall 11. Three walers 128 are installed inside the diaphragm wall 11, while two walers 128 are installed inside the active zone 12. It is understood that the number of walers 128 is determined based on the actual height of the excavation pit. In other embodiments, more walers may be used, but it is necessary to ensure that the walers 128 between the active zone 12 and the diaphragm wall 11 are disconnected; the walers 128 must not be located at a horizontal intersection of the active zone 12 and the diaphragm wall 11.

[0048] like Figure 3 As shown, several stainless steel ball bearings 125 are installed at the bottom of all sections to reduce the friction between the movable section 12 and the bottom diaphragm wall 11, thereby facilitating the movement of the movable section 12 toward the existing underground structure 3. Water-blocking plates 127 are installed on both the inner and outer sides of the bottom of all sections to prevent groundwater infiltration and to prevent soil from entering and affecting the movement of the sections. Figure 3As shown, all compartments are equipped with grouting pipes 126 extending to the bottom of the compartment. These pipes are used to inject anti-seepage and leak-stopping materials during construction and to inject concrete mortar after construction to ensure the integrity and waterproof performance of the structure. It should be noted that the rubber sealing strips 124, stainless steel ball bearings 125, and grouting pipes 126 on each compartment are all manufactured together with the compartments during prefabrication at the prefabrication plant.

[0049] like Figure 1 , Figure 2 , Figure 5 As shown, the support structure 2 consists of components such as servo inner support 21, inner support 22, columns 23, and walers 128. In this embodiment, the enclosure structure 1 is equipped with three horizontal support systems, and the three walers 128 are fixed to the inner wall of the enclosure structure 1 to achieve uniform load distribution. It can be understood that after the movable grid 12 is assembled with the underground continuous wall 11, the walers 128 of the movable grid 12 and the underground continuous wall 11 can fit together.

[0050] The support structure 2 includes several horizontal support systems. At the corresponding position of the active grid 12, each horizontal support system includes multiple servo internal supports 21 disposed between the diaphragm wall 11 and the active grid 12. In this embodiment, as... Figure 5 As shown, the support structure 2 includes three horizontal support systems. Each horizontal support system includes a waler 128 arranged circumferentially along the inner wall of the enclosure structure 1, and inner supports 22 arranged at the four corners of the diaphragm wall 11. The two ends of the inner supports 22 are fixedly connected to the walers 128. At the corresponding position of the active grid 12, each horizontal support system also includes multiple servo inner supports 21 arranged between the diaphragm wall 11 and the active grid 12. Each grid corresponds to a servo inner support 21, with one end of the servo inner support 21 arranged on the waler 128 of the active grid 12 and the other end arranged on the waler 128 of the diaphragm wall 11. The servo inner support 21 is arranged perpendicular to the active grid 12. In this embodiment, the active grid 12 is provided with three grids. In the upper two horizontal support systems corresponding to each grid, a servo inner support 21 is arranged between each grid and the diaphragm wall 11.

[0051] In the horizontal support system below the active area 12, an inner support 22 is installed at the position of the servo inner support 21. In this embodiment, the difference between the bottom horizontal support system and the two upper horizontal support systems is that, below the servo inner support 21 of the upper horizontal support system, three inner supports 22 are installed vertically between the walers 128 of the diaphragm wall 11. The three horizontal support systems achieve vertical support through multiple columns 23, ensuring stable stress distribution.

[0052] like Figure 6As shown, the monitoring system 4 consists of an inclinometer 41, a servo hydraulic cylinder assembly 211 of the servo internal support 21, and a monitoring center 42. In this embodiment, the monitoring center 42 is a computer. The monitoring center 42 is wirelessly connected to the inclinometer 41 and the servo hydraulic cylinder assembly 211 of the servo internal support 21, enabling real-time connection and data interaction. For example, the inclinometer 41 can be an existing RST digital inclinometer, which can connect to the monitoring center 42 via Bluetooth.

[0053] like Figure 6 As shown, the servo internal support 21 includes a servo hydraulic cylinder assembly 211, with support rods 212 fixedly connected to both ends of the servo hydraulic cylinder assembly 211; as Figure 5 As shown, the support rods 212 at both ends of the servo inner support 21 are connected to the waler 128. The servo hydraulic cylinder assembly 211 includes: a servo hydraulic cylinder and a PLC controller; the servo hydraulic cylinder is existing technology and generally consists of end caps, cylinder barrels, piston rods, piston assemblies, servo valves, sensing components (displacement sensors, load sensors), a base, and other main parts; wherein, the servo valves and sensing components are both connected to the PLC controller. In this embodiment, the monitoring center 42 is communicatively connected to the PLC controller of the servo cylinder assembly, specifically, an ESP32 wireless communication module can be used. The monitoring center 42 can transmit control commands to the servo hydraulic cylinder, causing it to perform corresponding actions.

[0054] During the excavation of the foundation pit, multiple inclinometers 41 collect real-time soil deformation data of the second area 62 and transmit the collected data to the monitoring center 42 via communication connection. The monitoring center 42 organizes, analyzes, and visualizes the data to promptly monitor the soil deformation. When the data collected by a certain inclinometer 41 exceeds the warning value, the calculation model in the monitoring center 42 calculates the required displacement of the corresponding grid, and the monitoring center 42 issues control commands to instruct the corresponding servo internal supports 21 to adjust the position of the corresponding grid to control soil deformation.

[0055] Throughout the entire excavation process, the inclinometer 41 and the servo internal support 21 will continuously feed back real-time data to the monitoring center 42, forming a real-time closed-loop feedback mechanism to ensure the stable operation and efficient control of the system.

[0056] like Figure 7 As shown, the grouting device 5 includes multiple grouting machines 51. The number of grouting machines 51 is the same as the number of cells in the active cell 12. Each grouting machine 51 is connected to multiple grout delivery pipes 52 through a grout outlet pipe. The number of grout delivery pipes 52 connected to each grouting machine 51 is equal to the number of grouting pipes 126 in each cell.

[0057] When the servo internal support 21 adjusts the position of the corresponding grid, a certain displacement (a few millimeters or centimeters) will occur between the grids or between the grids and the underground continuous wall 11. At this time, it is necessary to use the grouting device 5 to inject water-absorbing resin-based sealing material into the bottom of the movable grid 12. After absorbing water and expanding, this material can fill the gaps and form a seepage barrier. At the same time, due to its low strength, it will not affect the movement of the movable grid 12.

[0058] In this embodiment, by dividing the retaining structure 1 facing the existing underground structure 3 into independent grid units and configuring adjustable servo internal supports 21, a support system with regional self-adaptive capabilities is formed, thereby achieving precise deformation control for areas with different risk levels; the monitoring system 4 monitors the construction process in real time, obtains soil deformation data in a timely manner, and realizes dynamic adjustment based on feedback; the inclinometer 41 monitors soil deformation in real time, and then controls the corresponding servo internal supports 21 to output displacement, thereby moving the active grid 12 forward and actively controlling soil deformation.

[0059] This embodiment, by setting up servo-driven internal supports 21 and movable grids 12, can actively control the deformation of soil in different areas. Compared with passive control, this is safer and effectively solves the problem of insufficient adaptability of traditional support systems in complex engineering environments, significantly improving the safety and economy of foundation pit engineering. The economic benefit stems from the fact that in traditional passive support systems, the thickness of the diaphragm wall in the foundation pit is uniform. According to the barrel effect, this thickness depends on the thickness of the diaphragm wall adjacent to the existing structure, increasing costs. However, by setting up movable grids 12 and servo-driven internal supports 21 for active control, the thickness of the diaphragm wall 11 can be reduced compared to traditional support systems while ensuring its strength.

[0060] Example 2

[0061] This embodiment discloses a construction method for a shallow foundation pit zoned active control support structure according to Embodiment 1. The specific steps are as follows:

[0062] S1, Inclinometer 41 Installation

[0063] Before on-site construction, the inclinometer 41 is installed. Multiple holes are drilled between the existing underground structure 3 and the foundation pit area 63, and then the multiple inclinometers 41 are installed in the predetermined holes. The monitoring center 42 is connected to the inclinometer 41.

[0064] Understandably, at least one inclinometer 41 should be installed between each grid and the existing underground structure.

[0065] S2, Construction of Enclosing Structure 1;

[0066] According to the construction requirements, 11 steel cages for the underground continuous wall were fabricated to ensure that the specifications, models and welding quality of the steel bars met the design requirements; guide trenches were excavated around the foundation pit and guide walls were constructed; after the guide walls reached the design strength, the formwork was removed and support was provided, and finally backfilling was carried out.

[0067] Next, trench excavation will be carried out. Before construction, the trench will be divided into sections as required. The length of the 11th unit trench section of the underground continuous wall should be controlled within the range of 4 to 6 meters. During the excavation process, mud slurry will be injected simultaneously to ensure that the mud slurry surface in the trench is always 0.2 meters below the guide wall surface and 1 meter above the groundwater level.

[0068] After the excavation is completed, the silt and debris at the bottom of the trench are cleaned, and the mud in the trench is replaced with circulating mud. Then the joint pipe is inserted, the steel cage of the underground continuous wall 11 is hoisted into the trench, and finally underwater concrete is poured through the guide pipe and the joint pipe is pulled out.

[0069] When construction reaches the active zone 12, first install the rubber sealing strip 124 on the steel cage of the diaphragm wall 11 (understandably, it is installed on the side facing the active zone 12), and hoist it into the trench section; then pour underwater concrete through the tremie pipe to pour the diaphragm wall 11 to the bottom of the active zone 12; after the concrete has set, hoist the active zone 12 and complete the installation; set up the water baffle 127;

[0070] It is understandable that a base plate was made at the bottom of the activity area 12 in advance to prevent mud and concrete from entering the space where the ball bearings are located;

[0071] Repeat the above procedures until all trench sections are completed.

[0072] S3. Excavation and support of the foundation pit;

[0073] After the maintenance is completed, the foundation pit excavation begins; according to the construction requirements, after excavation to the specified depth, the internal support 22, servo internal support 21 and column 23 are assembled, and the first horizontal support system is installed; the current servo internal support 21 is then connected to the monitoring center 42.

[0074] Then continue excavating to a deeper, designated location, repeat the above steps, install the second horizontal support system, and continue until the final horizontal support system is completed;

[0075] While the foundation pit was being excavated, the monitoring system 4 also began to work. As the excavation depth increased, the lateral earth pressure and the deformation of the surrounding soil gradually intensified. The allowable range of soil deformation in the first area 61 was relatively large, and the support of the diaphragm wall 11 and the internal support 22 could meet the requirements. However, for the soil in the second area 62, due to the existence of the existing underground structure 3, the allowable deformation was relatively small, and relying solely on the diaphragm wall 11 for support could not effectively control it.

[0076] When the monitoring data of one inclinometer 41 shows that the soil deformation exceeds the warning value, the calculation model in the monitoring center 42 calculates the required output displacement of the corresponding grid (first grid 121, second grid 122, or third grid 123), and then issues a command to adjust the corresponding servo internal support 21, pushing the corresponding grid forward and actively controlling the soil deformation. The monitoring center 42 processes the monitoring data of multiple inclinometers 41 respectively, and calculates the output displacement of each grid through the calculation model, realizing independent control of the three grids.

[0077] During adjustment, water-absorbing resin-based sealing material is injected into the bottom of the active area 12 through the grouting device 5 to fill the gaps and prevent seepage.

[0078] S4. Overall construction of the activity area;

[0079] After the excavation and support of the foundation pit are completed, the inner wall water baffle 127 is opened in an orderly manner according to the process requirements, the residual water-absorbing resin sealing material is removed and the water baffle 127 is reset.

[0080] Then grouting is performed, and concrete mortar is poured into the bottom of the active grid 12 to achieve a rigid connection between the grid and the underground continuous wall 11.

[0081] Simultaneously, on-site processing of precast steel structure components was carried out, and multiple grid surfaces were connected into a whole through welding. At the same time, it was connected to the underground continuous wall 11 to form a collaborative force-bearing system.

[0082] Finally, support structure 2 was removed in sequence.

[0083] In S3 above, when the soil displacement data collected by the inclinometer 41 exceeds the warning value, the monitoring center 42 will update the data collected by the inclinometer 41 at this time. x1 Substitute the values ​​into the calculation model to perform the calculation, and then determine the horizontal displacement s that the active area 12 should achieve. x0 Then control the corresponding grid to move the corresponding horizontal displacement s. x0 .

[0084] Specifically, such as Figure 8 , Figure 9 As shown, the calculation model in this embodiment is as follows: There is a rectangular foundation pit with an excavation depth of H, a length of L, and a width of B near the existing underground structure 3. The minimum net distance between the excavation surface and the inclinometer 41 is x1, the vertical distance from the ground to the bottom of the existing underground structure 3 is h, and the outer diameter of the existing underground structure 3 is D. Figure 8 , Figure 9 A spatial coordinate system is established as shown.

[0085] Assumptions of the computational model:

[0086] (1) The soil is a homogeneous, elastic half-space, and the longitudinal axis of the existing underground structure 3 is parallel to the long side of the rectangular foundation pit;

[0087] (2) The interaction between active grid 12 and the soil is simplified to a Winker foundation model;

[0088] (3) The servo internal support 21 acts on the active grid 12, generating uniform pressure on the soil of the pit sidewall;

[0089] (4) The time and space factors of the foundation pit excavation are not considered, and the dewatering is not considered;

[0090] (5) The impact of the presence of the tunnel on the calculation of additional stress in the soil is not considered.

[0091] Based on the Mindlin horizontal load stress solution and the Winkler foundation model, in this calculation model, u x1 The calculation is performed using the following formula (1):

[0092] ;

[0093] In the formula: ;

[0094] λ For active control adjustment coefficients; i This is the i-th layer of stratified soil; n The number of stratified soil layers; h i The depth of the i-th soil layer in activity grid 12; a The width of the active area is 12; k i Let be the subgrade coefficient of the i-th soil layer; v i Let be the Poisson's ratio of the i-th soil layer; G i Let be the shear elastic modulus of the i-th soil layer; Let be the length of the infinitesimal element of the i-th soil layer along the y-axis. ξ i Let y be the y-coordinate of a point in the i-th soil layer along the y-axis; dη i Let be the length of the infinitesimal element of the i-th soil layer along the z-axis. η i Let be the z-axis coordinate of a point in the i-th soil layer along the z-axis direction.

[0095] Further simplification yields the following formula (2):

[0096] ;

[0097] And formula (3):

[0098] .

[0099] Among them, the horizontal displacement u produced by a point (0, ξ, η) in the active grid 12 of the near-ground existing structure 3 on a point (x1, y1, z1) on the inclinometer 41 is... x1 The horizontal displacement s of the active zone 12 under the action of the servo internal support 21 can be obtained by monitoring with the inclinometer 41. x0 (Displacement of the servo internal support 21 jacks).

[0100] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A shallow foundation pit zoned active control support structure, comprising a retaining structure, wherein a supporting structure is provided inside the retaining structure, characterized in that, It also includes a monitoring system, an inclinometer for the monitoring system between the retaining structure and the existing underground structure, and a grouting device for the top of the retaining structure facing the existing underground structure. The enclosure structure is divided into active compartments facing the existing underground structure and underground continuous walls facing other areas; The activity area is divided into multiple adjacent areas; At least one inclinometer shall be installed between each compartment and the existing underground structure; The height of the movable section is less than the height of the diaphragm wall. Several stainless steel ball bearings are installed at the bottom of the section to reduce the friction between the movable section and the bottom diaphragm wall, thereby facilitating the movement of the section. The supporting structure includes several horizontal support systems. Each horizontal support system includes walers arranged circumferentially along the inner wall of the enclosure structure, and internal supports arranged at the four corners of the diaphragm wall. The two ends of the internal supports are fixedly connected to the walers. It also includes servo internal supports that drive the movement of the grid. In the horizontal support system below the active grid, the servo internal supports are replaced by internal supports, which act on the diaphragm wall through the walers. The monitoring system also includes a servo-supported servo hydraulic cylinder group and a monitoring center; When the data monitored by a certain inclinometer shows that the soil deformation exceeds the warning value, the calculation model in the monitoring center calculates the displacement that the corresponding grid needs to output, and then adjusts the corresponding servo internal support to push the corresponding grid forward in order to control the soil deformation. All compartments are equipped with grouting pipes that extend to the bottom of the compartment. These pipes are used to inject anti-seepage and leak-stopping materials during construction and to inject concrete mortar after construction to ensure the integrity and waterproof performance of the structure. Water-retaining plates are installed on both the inner and outer sides of the bottom of the grid to prevent groundwater from seeping in and to block soil from entering and affecting the movement of the grid.

2. The shallow foundation pit zoned active control support structure as described in claim 1, characterized in that, Rubber sealing strips are fixedly installed on both sides of all sections; rubber sealing strips are also fixedly installed on the side where the diaphragm wall connects to the sections; the rubber sealing strips have a serrated structure that can interlock with each other, thereby enhancing the water-stopping effect.

3. The shallow foundation pit zoned active control support structure as described in claim 1, characterized in that, The horizontal support system uses multiple columns to provide vertical support, ensuring structural stability; the walers must not be installed where the activity zone intersects with the underground continuous wall horizontally.

4. The shallow foundation pit zoned active control support structure as described in claim 1, characterized in that, The monitoring center is wirelessly connected to the inclinometer and the servo hydraulic cylinder group of the servo internal support, enabling real-time connection and data interaction.

5. The shallow foundation pit zoned active control support structure as described in claim 1, characterized in that, The grouting device includes grouting machines with the same number of compartments. Each grouting machine is connected to multiple grout delivery pipes via a grout outlet pipe. The number of grout delivery pipes connected to each grouting machine is equal to the number of grouting pipes in each compartment.

6. A construction method for a shallow foundation pit zoned active control support structure as described in any one of claims 1-5, characterized in that, The specific steps are as follows: S1. Before construction, install the inclinometer and connect the monitoring center to the inclinometer. S2. Excavate guide trenches and construct guide walls around the foundation pit. Excavate trenches in sections and cast diaphragm walls in place. When the construction reaches the position of the movable grid, first install rubber sealing strips on the steel cage of the diaphragm wall and hoist it into the trench section. Then pour the diaphragm wall. After the concrete has set, hoist the movable grid and complete the installation. Repeat the above procedures until the diaphragm wall construction of all trench sections is completed. S3. After the maintenance is completed, the foundation pit is excavated to the specified depth and the first horizontal support system is installed; the current servo internal support is connected to the monitoring center; then the excavation continues to a deeper specified position, and the above steps are repeated to install the second horizontal support system until the last horizontal support system is completed. S4. After the excavation and support of the foundation pit are completed, the inner wall water baffle is opened in an orderly manner, the residual water-absorbing resin sealing material is removed and the water baffle is reset; then concrete mortar is poured into the bottom of the active area to achieve a rigid connection between the area and the underground continuous wall; multiple areas are connected into a whole by steel structure to form a coordinated force system; finally, the supporting structure is removed in sequence.

7. The construction method of a shallow foundation pit zoned active control support structure as described in claim 6, characterized in that, In S3, the monitoring system starts working when the foundation pit is excavated; as the excavation depth increases, the lateral earth pressure and the deformation of the surrounding soil gradually intensify; when the monitoring data of a certain inclinometer shows that the soil deformation exceeds the warning value, the calculation model in the monitoring center calculates the displacement that the corresponding grid needs to output, and then adjusts the corresponding servo internal support to push the corresponding grid forward in order to control the soil deformation. During adjustment, water-absorbing resin sealing material is injected into the bottom of the active area through a grouting device to fill the gaps and prevent seepage.

8. The construction method of a shallow foundation pit zoned active control support structure as described in claim 7, characterized in that, In the calculation model, a point (0, ...) in the load on the sidewall of the foundation pit of the existing underground structure near the ground is considered. ξ i , η i The horizontal displacement u produced by a point (x1, y1, z1) on the inclinometer x1 The horizontal displacement s of the active zone under the action of the servo internal support was obtained through inclinometer monitoring. x0 The horizontal displacement s of the active area is obtained from the functional relationship. x0 The functional relationship is as follows: ； ； In the formula: ; λ For active control adjustment coefficients; i This is the i-th layer of stratified soil; n The number of stratified soil layers; h i Let be the depth of the i-th layer of soil in the active area; The width of the active area grid pair; k i Let be the subgrade coefficient of the i-th soil layer; v i Let be the Poisson's ratio of the i-th soil layer; G i Let be the shear elastic modulus of the i-th soil layer; Let be the length of the infinitesimal element of the i-th soil layer along the y-axis. ξ i Let y be the y-coordinate of a point in the i-th soil layer along the y-axis; dη i Let be the length of the infinitesimal element of the i-th soil layer along the z-axis. η i Let be the z-axis coordinate of a point in the i-th soil layer along the z-axis direction.

Images