Construction method of concrete support servo system for ultra-deep foundation pit adjacent to subway

Abstract

The application provides a construction method of a concrete support servo system for an ultra-deep foundation pit adjacent to a subway, and belongs to the technical field of building construction. The method establishes a BIM model of an ultra-deep foundation pit and the surrounding environment for an operator; performs support design on the ultra-deep foundation pit according to the BIM model, to ensure the safety of construction; performs construction on the support inside the ultra-deep foundation pit; embeds a servo embedded part into a reserved installation space of the servo system; hoists and installs an assembly box on the servo embedded part; installs displacement monitoring equipment on the servo system after the assembly box is installed; performs axial force loading and servo; manually locks a mechanical lock after the axial force loading is completed; and the method can solve the problem that the existing concrete support method for an ultra-deep foundation pit adjacent to a subway cannot accurately control the support axial force to balance the constantly changing water and soil pressure, and cannot protect the foundation pit and the surrounding environment in all directions.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, and specifically relates to a construction method for a concrete support servo system for ultra-deep foundation pits adjacent to subway lines. Background Technology

[0002] With the rapid development of coastal cities, urban land resources are becoming increasingly scarce, and the development of underground space has become a focus of attention. However, limited underground space development has led to a large number of ultra-deep foundation pits for building construction, often located adjacent to subway lines, with limited construction sites and complex surrounding environments. Various units have raised higher requirements for the deformation of foundation pit support and subway tunnel structures adjacent to subway lines. The support for ultra-deep foundation pits has shifted from passive to active control of foundation pit deformation. A typical example is the servo system. Servo system construction technology is increasingly being applied to subway projects with steel supports, but there are currently few concrete building projects available for reference. Servo systems are widely used for monitoring axial force in steel supports and settlement and displacement of retaining walls, but less so for monitoring concrete supports in ultra-deep foundation pit building projects. In particular, there are very few cases of building projects using axial force servo systems for concrete supports in ultra-deep foundation pits adjacent to subway lines. The challenge lies in controlling the deformation of the subway structure during foundation pit excavation within the allowable design values ​​to ensure the safety of the operating subway.

[0003] Existing concrete support methods for ultra-deep foundation pits adjacent to subway lines cannot accurately control the axial force of the support to balance the constantly changing water and soil pressure, making it difficult to protect the foundation pit and its surrounding environment in all aspects. Summary of the Invention

[0004] In view of this, the present invention provides a construction method for a concrete support servo system for ultra-deep foundation pits adjacent to subways, which can solve the problem that existing concrete support methods for ultra-deep foundation pits adjacent to subways cannot accurately control the axial force of the support to balance the constantly changing water and soil pressure, and are difficult to protect the foundation pit and the surrounding environment in all aspects.

[0005] This invention is implemented as follows:

[0006] This invention provides a construction method for a concrete support servo system adjacent to an ultra-deep foundation pit of a subway, comprising the following steps:

[0007] S10: Operators create a BIM model of the ultra-deep foundation pit and its surrounding environment;

[0008] S20: The operator designs the support structure for the ultra-deep foundation pit based on the BIM model of the ultra-deep foundation pit and its surrounding environment to ensure the safety of construction.

[0009] S30: Construct the support inside the ultra-deep foundation pit, reserving installation space for the servo system;

[0010] S40: Embed the servo pre-embedded component into the reserved installation space of the servo system;

[0011] S50: Hoist the assembly box and install it on the servo embedded part;

[0012] S60: After the assembly box is installed, install the displacement monitoring equipment onto the servo system;

[0013] S70: Apply axial force and perform servo operation on the servo system;

[0014] S80: After the axial force is applied, manually lock the mechanical lock;

[0015] S90: Unload and remove the assembly box from the site.

[0016] The technical effects of the construction method of a concrete support servo system for ultra-deep foundation pits adjacent to subways provided by this invention are as follows: Operators establish a BIM model of the ultra-deep foundation pit and its surrounding environment; based on the BIM model, support design is performed for the ultra-deep foundation pit to ensure construction safety; the internal support of the ultra-deep foundation pit is constructed, reserving installation space for the servo system; servo embedded parts are pre-embedded into the reserved installation space for the servo system; the assembly box is hoisted and installed on the servo embedded parts; after the assembly box is installed, displacement monitoring equipment is installed on the servo system; axial force is applied to the servo system; after axial force application, the mechanical lock is manually locked; the assembly box is unloaded and removed from the site. This effectively ensures the safety of the subway tunnel, saves construction time and costs, and achieves the goal of cost reduction and efficiency improvement in construction. Based on the deformation data of the foundation pit and surrounding protected structures, the changing trend of soil pressure is comprehensively judged, which can solve the problem that existing concrete support methods for ultra-deep foundation pits adjacent to subways cannot accurately control the support axial force to balance the constantly changing water and soil pressure, and are difficult to comprehensively protect the foundation pit and its surrounding environment.

[0017] Based on the above technical solution, the construction method of the concrete support servo system for ultra-deep foundation pits adjacent to subways of the present invention can be further improved as follows:

[0018] The specific steps for the operator to design the support structure for the ultra-deep foundation pit based on the BIM model of the pit and its surrounding environment include:

[0019] The first step is for the operators to design a multi-layer reinforced concrete support servo reaction structure based on the BIM model of the ultra-deep foundation pit and its surrounding environment.

[0020] The second step is to install a support connecting beam at the servo connection point;

[0021] The third step is to calculate the stiffness of the planar support system of the connecting beam based on the BIM model of the ultra-deep foundation pit and its surrounding environment. The multi-layer reinforced concrete support servo reaction structure provides a reaction force to the entire ultra-deep foundation pit that is greater than the stiffness of the planar support system, thereby improving the active deformation control capability of the multi-layer reinforced concrete support servo reaction structure.

[0022] Furthermore, the multi-layer reinforced concrete support servo reaction structure is designed with a distributed hydraulic control mode, including a servo support main control cabinet, multiple servo support components, multiple small hydraulic pump stations, and multiple double mechanical lock frames. The multiple small hydraulic pump stations are respectively installed in the support head assembly of the servo support components, forming a distributed power unit. The distributed power unit is connected in series with the servo support main control cabinet through an RS485 signal line and a 48V power line. The multiple double mechanical lock frames are respectively configured on the support head of each servo support component to improve the safety redundancy of the support axial force servo system.

[0023] Furthermore, a small hydraulic pump station is separately installed in the support head assembly of each servo support to form a distributed power unit. The distributed power unit is connected in series with the main control cabinet of the servo support through an RS485 signal line and a 48V power line. A double mechanical lock frame is configured on the support head of each servo support to improve the safety redundancy of the support axis force servo system.

[0024] Furthermore, the specific steps for constructing the supports inside the ultra-deep foundation pit and reserving installation space for the servo system include:

[0025] The first step is for the operators to determine the dimensions, depth, and geological conditions of the ultra-deep foundation pit based on the BIM model of the ultra-deep foundation pit and its surrounding environment.

[0026] The second step is to install and fix anchor bolts at the bottom of the ultra-deep foundation pit;

[0027] The third step is to fix steel plates inside the ultra-deep foundation pit, with the steel plates arranged around the anchor bolts;

[0028] The fourth step is to pour concrete between the steel plate and the anchor rod to form the support structure inside the ultra-deep foundation pit;

[0029] The fifth step is to test the stability of the supporting structure and remove the steel plate after confirming that it can stably support the ultra-deep foundation pit.

[0030] The sixth step involves reserving installation space for the servo system inside the ultra-deep foundation pit, followed by another concrete pour to further reinforce the support inside the ultra-deep foundation pit.

[0031] Furthermore, the specific steps for installing and fixing anchor bolts at the bottom of the ultra-deep foundation pit include:

[0032] The first step is to divide the bottom area of ​​the ultra-deep foundation pit into 3m*3m squares, and determine the installation position of the anchor bolt at the center of the square.

[0033] The second step is to drill a hole at the installation location of the anchor rod, the diameter of which is the same as the diameter of the anchor rod.

[0034] The third step is to install anchor nuts in the drill hole, making sure the anchor nuts are tightly attached to the drill rod;

[0035] The fourth step is to manually inspect the stability of the anchor bolt installation. After confirming that it is stable, concrete is filled at the position of the anchor bolt and the corresponding hole. The filling height of the concrete is greater than the height of the anchor bolt nut.

[0036] The fifth step is to fix the anchor bolts after the concrete filling is completed;

[0037] The sixth step involves manually verifying the anchoring force between the anchor rod and the concrete, the position of the anchor rod, and the fixing point.

[0038] Step 7: After the anchor bolts are fixed, backfill the ultra-deep foundation pit.

[0039] Furthermore, the specific steps of filling concrete at the position of the anchor rod and the corresponding hole after confirming stability, wherein the filling height of the concrete is greater than the height of the anchor rod nut, include:

[0040] The first step is to insert the concrete-filled pipe into the bottom of the anchor bolt installation hole;

[0041] The second step is to gradually fill concrete between the anchor rod and the hole from bottom to top;

[0042] The third step involves continuously vibrating the concrete during the filling process to dislodge air bubbles from the concrete between the anchor rod and the hole, ensuring the compactness of the filled concrete.

[0043] Furthermore, the specific steps for testing the stability of the supporting structure to determine its ability to stably support the ultra-deep foundation pit before removing the steel plate include:

[0044] The first step is for the operators to classify the supporting structure into different levels based on the BIM model of the ultra-deep foundation pit and its surrounding environment, and obtain the first weight allocation result.

[0045] The second step involves the operator obtaining a second weight allocation result based on the force and swaying conditions of the support structure in the actual environment.

[0046] The third step involves the operator performing voxelization of the BIM model of the ultra-deep foundation pit and its surrounding environment based on a clustering algorithm to obtain the support structure level analysis results and the third weight allocation results.

[0047] The fourth step is to obtain the stability evaluation result of the support structure based on the first weight allocation result, the second weight allocation result, and the third weight allocation result.

[0048] Fifth, after assessing the stability of the supporting structure and confirming that it can stably support the ultra-deep foundation pit, the sheet piles are removed.

[0049] The specific steps by which the operator performs voxelization of the BIM model of the ultra-deep foundation pit and its surrounding environment based on a clustering algorithm to obtain the support structure level analysis results and the third weight allocation results include:

[0050] The steel plate is scanned to generate a point cloud image;

[0051] The initial point cloud is voxelized to obtain multiple voxel cubes;

[0052] Select any of the voxel cubes as the center cube, calculate the fitting plane normal vector in each adjacent cube of the center cube, and calculate the angle between each fitting plane normal vector and the center fitting plane normal vector of the center cube. When the angle is less than a set angle threshold, it is determined that the center cube and the adjacent cube can be fitted to form a cube fitting plane, and the preliminary point cloud of the cube fitting plane is determined.

[0053] The three-dimensional data of the cube fitting plane is projected onto the cube fitting plane to form two-dimensional data. The two-dimensional data is divided into grids, and the number of points in each grid is compared with a set point count threshold. Grids with a point count greater than the point count threshold are numbered as new data points. The new data points are numbered and classified based on a clustering algorithm to obtain the fine segmentation plane of the cube fitting plane.

[0054] Repeat the above process until the initial point cloud is traversed, all the fine segmentation planes are obtained, and the over-segmented planes in the fine segmentation planes are optimized;

[0055] Planar division is performed on the constructed BIM model of the ultra-deep foundation pit and its surrounding environment to obtain the level analysis results of the supporting structure and the third weight allocation results.

[0056] Furthermore, the specific steps of fixing the steel plate inside the ultra-deep foundation pit, wherein the steel plate is arranged around the anchor bolt, include:

[0057] The first step is to dig an installation pit around the anchor bolt;

[0058] The second step is to perform low-temperature stretching on the steel plate according to the curvature and radius of the mounting pit to form a steel plate with the same curvature and radius as the mounting pit.

[0059] The third step is to fix the steel plate in the installation pit so that the steel plate surrounds the anchor rod.

[0060] The specific steps for the construction personnel to establish a BIM model of the ultra-deep foundation pit and its surrounding environment based on the actual conditions of the pit include:

[0061] The first step involves the operators classifying the design drawings, installation locations, support points, and support methods of the ultra-deep foundation pit and its surrounding environment using a hierarchical classification method. They then propose an information organization-based coding rule to encode each part of the ultra-deep foundation pit and its surrounding environment.

[0062] The second step involves the operators standardizing the parameters of the ultra-deep foundation pit and its surrounding environment, creating a shared parameter file for use in different families and projects.

[0063] The third step is for the operator to input the shared parameter file into the Graphisoft Archicad software platform, and construct a three-dimensional model of each part of the ultra-deep foundation pit and its surrounding environment according to the design drawings, installation location, support points and support methods of the ultra-deep foundation pit and its surrounding environment. The three-dimensional models are then classified and summarized to establish a family library of the ultra-deep foundation pit and its surrounding environment.

[0064] The fourth step involves the operator calling upon various components in the ultra-deep foundation pit and surrounding environment family library based on the actual installation situation of the ultra-deep foundation pit and surrounding environment. Through external data file drivers, the operator modifies the structural parameters of the ultra-deep foundation pit and surrounding environment, generating corresponding instances.

[0065] The fifth step involves the operators performing unified assembly to form a complete BIM model of the ultra-deep foundation pit and its surrounding environment.

[0066] Furthermore, the step of performing low-temperature stretching on the steel plate according to the curvature and radius of the mounting pit to form a steel plate with the same curvature and radius as the mounting pit includes:

[0067] The first step is recrystallization treatment. The steel plate is cut into appropriate sizes and placed in an inert protective atmosphere for heat treatment. The temperature of the heat treatment is 700-800℃ and the holding time is 30-60 minutes. Then it is cooled to room temperature in the air.

[0068] The second step is low-temperature hot stretching treatment, in which the recrystallized steel plate is subjected to hot stretching deformation with different degrees of bending at low temperature. The hot stretching deformation temperature is 300-400℃, the elongation of the hot stretching deformation is 10-30%, and the stretching speed of the hot stretching deformation is 1-5mm / min. Then it is cooled to room temperature in air.

[0069] The third step is high-temperature recovery treatment. The steel plate after low-temperature hot stretching is placed in a reducing protective atmosphere and heated at high temperature. The high-temperature heating temperature is 500-600℃ and the holding time is 1-2 hours.

[0070] The fourth step is solution treatment. The steel plate after high-temperature recovery treatment is further heated for solution treatment. The heating temperature is 1000-1100℃ and the holding time is 10-30 minutes.

[0071] The fifth step is quenching. The steel plate after solution treatment is quenched by rapid cooling to obtain a steel plate with the same arc and curvature as the mounting pit.

[0072] Compared with existing technologies, the beneficial effects of the construction method for a concrete support servo system adjacent to an ultra-deep foundation pit provided by this invention are as follows: Operators establish a BIM model of the ultra-deep foundation pit and its surrounding environment; based on the BIM model, support design is performed on the ultra-deep foundation pit to ensure construction safety; the internal support of the ultra-deep foundation pit is constructed, reserving installation space for the servo system; servo embedded parts are pre-embedded into the reserved installation space for the servo system; the assembly box is hoisted and installed on the servo embedded parts; after the assembly box is installed... The displacement monitoring equipment is installed on the servo system; axial force is applied and servo is applied to the servo system; after the axial force is applied, the mechanical lock is manually locked; the assembly box is unloaded and removed from the site. This effectively ensures the safety of the subway tunnel, saves construction time and costs, and achieves the goal of reducing costs and increasing efficiency in construction. Based on the deformation data of the foundation pit and the surrounding protective structures, the changing trend of soil pressure is comprehensively judged. This can solve the problem that the existing concrete support method for ultra-deep foundation pits adjacent to subways cannot accurately control the axial force of the support to balance the constantly changing water and soil pressure, and it is difficult to protect the foundation pit and the surrounding environment in all aspects. Attached Figure Description

[0073] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0074] Figure 1 A flowchart illustrating the construction method of a concrete support servo system for ultra-deep foundation pits adjacent to subway lines.

[0075] The attached diagram lists the components represented by each number as follows: Detailed Implementation

[0076] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0077] like Figure 1 The diagram shows an operation flowchart of a construction method for a concrete support servo system adjacent to an ultra-deep foundation pit of a subway, provided by the present invention. The method includes the following steps:

[0078] S10: Operators create a BIM model of the ultra-deep foundation pit and its surrounding environment;

[0079] S20: Operators design support for the ultra-deep foundation pit based on the BIM model of the ultra-deep foundation pit and its surrounding environment to ensure the safety of construction.

[0080] S30: Construct the support inside the ultra-deep foundation pit and reserve installation space for the servo system;

[0081] S40: Embed the servo pre-embedded parts into the reserved installation space of the servo system;

[0082] S50: Hoist the assembly box and install it on the servo embedded part;

[0083] S60: After the assembly box is installed, install the displacement monitoring equipment onto the servo system;

[0084] S70: Performs axial force loading and servo control on the servo system;

[0085] S80: After the axial force is applied, manually lock the mechanical lock;

[0086] S90: Unload and remove the assembly box from the market.

[0087] During operation, operators create a BIM model of the ultra-deep foundation pit and its surrounding environment; based on the BIM model, they design the support structure for the ultra-deep foundation pit to ensure construction safety; they construct the internal supports of the ultra-deep foundation pit, reserving installation space for the servo system; they embed the servo pre-installed parts into the reserved installation space for the servo system; they hoist the assembly box and install it on the servo pre-installed parts; after the assembly box is installed, they install the displacement monitoring equipment onto the servo system; they apply axial force to the servo system and apply servo control; after the axial force is applied, they manually lock the mechanical lock; finally, they unload and remove the assembly box from the site.

[0088] In the aforementioned technical solution, the specific steps for operators to design the support structure for the ultra-deep foundation pit based on the BIM model of the pit and its surrounding environment include:

[0089] The first step is for the operators to design a multi-layer reinforced concrete support servo reaction structure based on the BIM model of the ultra-deep foundation pit and its surrounding environment.

[0090] The second step is to install a support connecting beam at the servo connection point;

[0091] The third step is to calculate the stiffness of the planar support system of the connecting beam based on the BIM model of the ultra-deep foundation pit and its surrounding environment. The multi-layer reinforced concrete support servo reaction structure provides a reaction force to the entire ultra-deep foundation pit that is greater than the stiffness of the planar support system, which is used to improve the active deformation control capability of the multi-layer reinforced concrete support servo reaction structure.

[0092] Furthermore, in the above technical solution, the multi-layer reinforced concrete support servo reaction structure is designed to adopt a distributed hydraulic control mode, including a servo support main control cabinet, multiple servo support components, multiple small hydraulic pump stations, and multiple double mechanical lock frames. The multiple small hydraulic pump stations are respectively installed in the support head assembly of the servo support component, and the multiple small hydraulic pump stations form a distributed power unit. The distributed power unit is connected in series with the servo support main control cabinet through RS485 signal line and 48V power line. The multiple double mechanical lock frames are respectively configured on the support head of each servo support component to improve the safety redundancy of the support axial force servo system.

[0093] Furthermore, in the above technical solution, a small hydraulic pump station is installed separately in the support head assembly of each servo support to form a distributed power unit. The distributed power unit is connected in series with the main control cabinet of the servo support through an RS485 signal line and a 48V power line. A double mechanical lock frame is configured on the support head of each servo support to improve the safety redundancy of the support axis force servo system.

[0094] Furthermore, in the above technical solution, the specific steps for constructing the supports inside the ultra-deep foundation pit and reserving installation space for the servo system include:

[0095] The first step is for the operators to determine the dimensions, depth, and geological conditions of the ultra-deep foundation pit based on the BIM model of the ultra-deep foundation pit and its surrounding environment.

[0096] The second step is to install and secure anchor bolts at the bottom of the ultra-deep foundation pit;

[0097] The third step is to fix steel plates inside the ultra-deep foundation pit, with the steel plates placed around the anchor bolts;

[0098] The fourth step is to pour concrete between the steel plate and the anchor rod to form a support structure inside the ultra-deep foundation pit.

[0099] The fifth step is to test the stability of the supporting structure and remove the steel plate after confirming that it can stably support the ultra-deep foundation pit.

[0100] The sixth step involves reserving installation space for the servo system inside the ultra-deep foundation pit, followed by another concrete pour to further reinforce the support inside the pit.

[0101] Furthermore, in the above technical solution, the specific steps for installing and fixing anchor bolts at the bottom of the ultra-deep foundation pit include:

[0102] The first step is to divide the bottom of the ultra-deep foundation pit into 3m*3m squares, and determine the installation position of the anchor bolt at the center of the square.

[0103] The second step is to drill holes at the installation location of the anchor bolt, with the diameter of the holes being the same as the diameter of the anchor bolt.

[0104] The third step is to install anchor nuts in the drilled hole, and to make sure the anchor nuts are tightly attached to the drill rod.

[0105] The fourth step is to manually inspect the stability of the anchor bolt installation. Once it is confirmed to be stable, concrete is filled at the position of the anchor bolt and the corresponding hole. The height of the concrete filling is greater than the height of the anchor bolt nut.

[0106] The fifth step is to fix the anchor bolts after the concrete filling is completed;

[0107] The sixth step is to manually verify the anchoring force between the anchor bolt and the concrete, the position of the anchor bolt, and the fixing point.

[0108] The seventh step is to backfill the ultra-deep foundation pit after the anchor bolts are fixed.

[0109] Furthermore, in the above technical solution, after ensuring stability, the specific steps for filling the anchor bolt and corresponding hole with concrete, wherein the concrete filling height is greater than the height of the anchor bolt nut, include:

[0110] The first step is to insert the concrete-filled pipe opening to the bottom of the anchor bolt installation hole;

[0111] The second step is to gradually fill the space between the anchor rod and the hole from bottom to top with concrete.

[0112] The third step involves continuously vibrating the concrete during the filling process to dislodge air bubbles from the concrete between the anchor rod and the hole, ensuring the compactness of the filled concrete.

[0113] Furthermore, in the above technical solution, the specific steps for testing the stability of the supporting structure and determining its ability to stably support the ultra-deep foundation pit before removing the steel plate include:

[0114] The first step is for the operators to classify the supporting structure into different levels based on the BIM model of the ultra-deep foundation pit and its surrounding environment, and obtain the first weight allocation result.

[0115] The second step involves the operator obtaining the second weight allocation result based on the force and swaying conditions of the support structure in the actual environment.

[0116] The third step involves operators using a clustering algorithm to perform voxelization of the BIM model of the ultra-deep foundation pit and its surrounding environment to obtain the results of the support structure level analysis and the third weight allocation result.

[0117] The fourth step is to obtain the stability evaluation results of the supporting structure based on the first weight allocation result, the second weight allocation result, and the third weight allocation result.

[0118] The fifth step is to remove the sheet piles after assessing the stability of the supporting structure and confirming that it can stably support the ultra-deep foundation pit.

[0119] The specific steps for operators to obtain the third weight allocation result by performing voxelization of the BIM model of the ultra-deep foundation pit and its surrounding environment based on clustering algorithms to obtain the support structure level analysis results include:

[0120] The steel plate is scanned to generate a point cloud image;

[0121] The initial point cloud is voxelized to obtain multiple voxel cubes;

[0122] Select any voxel cube as the center cube, calculate the fitting plane normal vector in each adjacent cube of the center cube, and calculate the angle between each fitting plane normal vector and the center fitting plane normal vector of the center cube. When the angle is less than the set angle threshold, it is determined that the center cube and the adjacent cube can be fitted to form a cube fitting plane, and the preliminary point cloud of the cube fitting plane is determined.

[0123] The three-dimensional data of the cube fitting plane is projected onto the cube fitting plane to form two-dimensional data. The two-dimensional data is divided into grids, and the number of points in each grid is compared with a set point count threshold. Grids with more points than the point count threshold are numbered as new data points. The new data points are numbered and classified based on a clustering algorithm to obtain the fine segmentation plane of the cube fitting plane.

[0124] Repeat the above process until the initial point cloud is traversed, all fine segmentation planes are obtained, and the over-segmented planes in the fine segmentation planes are optimized;

[0125] Planar division was performed on the constructed ultra-deep foundation pit and its surrounding environment BIM model to obtain the results of the support structure level analysis and the third weight allocation results.

[0126] Furthermore, in the above technical solution, the specific steps for fixing steel plates inside the ultra-deep foundation pit, with the steel plates positioned around the anchor bolts, include:

[0127] The first step is to dig an installation pit around the anchor bolt;

[0128] The second step is to perform low-temperature stretching of the steel plate according to the curvature and radius of the installation pit to form a steel plate with the same curvature and radius as the installation pit.

[0129] The third step is to fix the steel plate in the installation pit so that the steel plate surrounds the anchor rod.

[0130] The specific steps for construction personnel to create a BIM model of the ultra-deep foundation pit and its surrounding environment based on the actual conditions of the pit include:

[0131] The first step involves the operators classifying the design drawings, installation locations, support points, and support methods of the ultra-deep foundation pit and its surrounding environment into hierarchical categories. They then propose a coding rule based on information organization to encode each part of the ultra-deep foundation pit and its surrounding environment.

[0132] The second step is for operators to standardize the parameters of the ultra-deep foundation pit and its surrounding environment, and create a shared parameter file for use in different families and projects.

[0133] The third step is for the operator to input the shared parameter file into the Graphisoft Archicad software platform, and construct a three-dimensional model of each part of the ultra-deep foundation pit and its surrounding environment according to the design drawings, installation location, support points and support methods of the ultra-deep foundation pit and its surrounding environment. The three-dimensional models are then classified and summarized to establish a family library of ultra-deep foundation pits and their surrounding environment.

[0134] The fourth step involves the operator calling up various components in the ultra-deep foundation pit and surrounding environment family library based on the actual installation situation of the ultra-deep foundation pit and surrounding environment. Through external data file driving, the operator modifies the structural parameters of the ultra-deep foundation pit and surrounding environment and generates corresponding instances.

[0135] The fifth step involves the operators performing unified assembly to create a complete BIM model of the ultra-deep foundation pit and its surrounding environment.

[0136] Furthermore, in the above technical solution, the step of performing low-temperature stretching on the steel plate according to the curvature and radius of the mounting pit to form a steel plate with the same curvature and radius as the mounting pit includes:

[0137] The first step is recrystallization treatment. The steel plate is cut into appropriate sizes and placed in an inert protective atmosphere for heat treatment. The temperature of the heat treatment is 700-800℃ and the holding time is 30-60 minutes. Then it is cooled to room temperature in the air.

[0138] The second step is low-temperature hot stretching treatment, in which the recrystallized steel plate is subjected to hot stretching deformation with different degrees of bending at low temperature. The hot stretching deformation temperature is 300-400℃, the elongation of the hot stretching deformation is 10-30%, and the stretching speed of the hot stretching deformation is 1-5mm / min. Then it is cooled to room temperature in air.

[0139] The third step is high-temperature recovery treatment. The steel plate after low-temperature hot stretching is placed in a reducing protective atmosphere and heated at high temperature. The high-temperature heating temperature is 500-600℃ and the holding time is 1-2 hours.

[0140] The fourth step is solution treatment. The steel plate after high-temperature recovery treatment is further heated for solution treatment. The heating temperature is 1000-1100℃ and the holding time is 10-30 minutes.

[0141] The fifth step is quenching. The steel plate after solution treatment is quenched by rapid cooling to obtain a steel plate with the same arc and curvature as the mounting pit.

[0142] Example:

[0143] First, a multi-layer reinforced concrete support servo reaction structure design was implemented. Support connecting beams were installed at the servo connection points. When calculating the stiffness of the planar support system, the contribution of the plate to the stiffness was considered as a reserve. The reaction structure provides sufficient reaction force for the entire support system, improving the support system's ability to actively control deformation. The servo system innovatively adopts a distributed hydraulic control mode. A small hydraulic pump station is installed separately in each support head assembly, forming a distributed power unit. Each distributed power unit is connected in series with the main control cabinet via an RS485 signal line and a 48V power line. Each support head is equipped with a double mechanical locking frame to improve the safety redundancy of the support axial force servo system. The hydraulic pump output system's set hydraulic oil flow rate is directly adjusted by controlling the speed of the variable frequency motor. Simultaneously, a PID algorithm is used to automatically adjust the system's control input based on the error between the target desired oil pressure and the actual system output oil pressure. After the design is completed, according to the on-site construction organization, earthwork excavation and internal support construction are carried out simultaneously. The servo equipment can only be installed after the internal support concrete strength reaches the design requirements. Before formal construction, a monitoring room is set up. Based on the on-site construction conditions, the oil pipeline routing and pump station placement are planned, with the pump station placed as close to the edge as possible. Each servo unit is equipped with one protection device and one concrete pier failure protection device. A multi-point distributed concrete support servo system connection technology is adopted, which includes a concrete support servo system connection device and a concrete pier failure protection device. The concrete pier failure protection device is installed between the connecting beam and the support structure. The servo system connection device is connected to the support connecting beam using a pre-embedded anchor plate and to the support structure using a rear anchor steel plate, ensuring better and more even distribution of the servo axial force on the support structure. A tower crane is used on-site to transport the equipment directly to the pit, and forklifts are used to promptly transfer the equipment to the construction platforms at each level. Horizontal transportation and installation within the pit will be carried out using forklifts or mobile gantry cranes. During horizontal transportation, attention should be paid to obstacles on site, and a reasonable route should be found to ensure transportation safety. The servo jack piston can be selected with a 200mm stroke specification; considering safety during operation, the working stroke can be set <180mm. Since subsequent loading and measurement and control require a reserved stroke, the distance between the end face of the support head assembly and the diaphragm wall must be <100mm. Inspect the rear anchor plate on one side of the diaphragm wall and the embedded steel plate on the other side of the joist beam to confirm that they meet the installation requirements. Secure the ultrasonic sensor to the installed support head. Secure the machine vision measuring instrument to the east and west diaphragm walls and take protective measures to ensure the reference point is not disturbed. Install the target on the north diaphragm wall, then align the measuring instrument with the target for displacement monitoring. Before equipment installation, secure the machine vision measuring instrument and target to the diaphragm wall and take protective measures; put it into use before servo installation. The axial force application of the servo system should be carried out according to the design requirements, strictly following the different excavation and support conditions for graded loading. The axial force should be applied slowly and in three stages (the same applies during unloading):

[0144] 1) Initial loading to 50% of the design axial force;

[0145] 2) Apply the load a second time to 70% of the design axial force;

[0146] 3) Apply the load a second time to 100% of the design axial force.

[0147] The transition loading technology of the multi-layer reinforced concrete support servo system selects several diaphragm walls with small servo axial force differences as transition sections, and increases the servo axial force in the transition sections in stages. This reduces the risk of leakage at the joints of the diaphragm walls caused by excessive differences in servo axial force at the junctions of different support sections. When the concrete supports of adjacent sections do not reach the design loading strength due to phased construction, the end servo axial force is applied according to the linear transition loading principle, solving the problem of leakage risk caused by excessive stress differences in the diaphragm walls at the construction sites due to differences in construction time between different sections. An innovative excavation face control criterion is established. By adjusting the pre-applied axial force of the two supports at the excavation face and the upper support, iterative calculations are performed until the tunnel deformation meets the requirements. The servo axial force threshold of each support is determined. By adjusting the axial force of the support closest to the deformation control point, the lateral deformation of the foundation pit retaining structure is effectively controlled, forming the basic criterion for dynamic axial force control.

[0148] Numerical simulation analysis was used to sequentially increase the axial force from the first servo to the last inner support. The closer to the active axial force location, the greater the impact; the upper support axial force has a significant influence on the lateral deformation of the lower retaining structure. Therefore, an innovative excavation face control criterion was established, effectively controlling the lateral deformation of the foundation pit retaining structure by adjusting the axial force of the support closest to the deformation control point. A servo system axial force dynamic control technology was adopted, using the excavation face control criterion to dynamically control the servo axial force, solving the problem of actual deformation of tunnels and foundation pits exceeding theoretical values ​​due to the superposition of geological complexity and actual working conditions, achieving real-time active control of foundation pit and subway deformation. After the axial force was applied to 100% of the design value and held for five minutes, the mechanical lock was manually locked. A gap of approximately 0.5mm was maintained between the mechanical lock and the support head assembly. After completion, a protective sleeve was added to the mechanical lock to prevent contamination by on-site mud and other debris. As the basement structure is constructed, the internal supports are dismantled, and the servo assembly box is dismantled accordingly. The dismantled equipment is first piled up on the construction platforms on each floor. When the transport vehicles arrive, forklifts or mobile gantry cranes are used to transport it to the tower crane hoisting position, and then the tower crane is used to transport it into the transport vehicle for timely removal from the site.

[0149] Specifically, the principle of this invention is as follows: operators establish a BIM model of the ultra-deep foundation pit and its surrounding environment; based on the BIM model, design the support for the ultra-deep foundation pit to ensure construction safety; construct the internal support of the ultra-deep foundation pit, reserving installation space for the servo system; embed the servo pre-embedded parts into the reserved installation space for the servo system; hoist the assembly box and install it on the servo pre-embedded parts; after the assembly box is installed, install the displacement monitoring equipment on the servo system; apply axial force to the servo system and perform servo operation; after the axial force is applied, manually lock the mechanical lock; unload and remove the assembly box from the site.

Claims

1. A construction method for a concrete support servo system adjacent to an ultra-deep foundation pit of a subway, characterized in that, Includes the following steps: S10: Operators create a BIM model of the ultra-deep foundation pit and its surrounding environment; S20: The operator designs the support structure for the ultra-deep foundation pit based on the BIM model of the ultra-deep foundation pit and its surrounding environment to ensure the safety of construction. S30: Construct the support inside the ultra-deep foundation pit, reserving installation space for the servo system; S40: Embed the servo pre-embedded component into the reserved installation space of the servo system; S50: Hoist the assembly box and install it on the servo embedded part; S60: After the assembly box is installed, install the displacement monitoring equipment onto the servo system; S70: Apply axial force and perform servo operation on the servo system; S80: After the axial force is applied, manually lock the mechanical lock; S90: Unload and remove the assembly box from the site; The specific steps for the operator to design the support structure for the ultra-deep foundation pit based on the BIM model of the ultra-deep foundation pit and its surrounding environment include: The first step is for the operators to design a multi-layer reinforced concrete support servo reaction structure based on the BIM model of the ultra-deep foundation pit and its surrounding environment. The second step is to install a support connecting beam at the servo connection point; The third step is to calculate the stiffness of the planar support system of the connecting beam based on the BIM model of the ultra-deep foundation pit and the surrounding environment. The multi-layer reinforced concrete support servo reaction structure provides a reaction force to the entire ultra-deep foundation pit that is greater than the stiffness of the planar support system, which is used to improve the active deformation control capability of the multi-layer reinforced concrete support servo reaction structure. The specific steps for constructing the supports inside the ultra-deep foundation pit and reserving installation space for the servo system include: The first step is for the operators to determine the dimensions, depth, and geological conditions of the ultra-deep foundation pit based on the BIM model of the ultra-deep foundation pit and its surrounding environment. The second step is to install and fix anchor bolts at the bottom of the ultra-deep foundation pit; The third step is to fix steel plates inside the ultra-deep foundation pit, with the steel plates arranged around the anchor bolts; The fourth step is to pour concrete between the steel plate and the anchor rod to form the support structure inside the ultra-deep foundation pit; The fifth step is to test the stability of the supporting structure and remove the steel plate after confirming that it can stably support the ultra-deep foundation pit. The sixth step is to pour concrete again after reserving installation space for the servo system inside the ultra-deep foundation pit to further reinforce the support inside the ultra-deep foundation pit. The specific steps for installing and fixing anchor bolts at the bottom of the ultra-deep foundation pit include: The first step is to divide the bottom area of ​​the ultra-deep foundation pit into 3m*3m squares, and determine the installation position of the anchor bolt at the center of the square. The second step is to drill a hole at the installation location of the anchor rod, the diameter of which is the same as the diameter of the anchor rod. The third step is to install anchor nuts in the drilled hole, and to make the anchor nuts fit tightly against the drill rod. The fourth step is to manually inspect the stability of the anchor bolt installation. After confirming that it is stable, concrete is filled at the position of the anchor bolt and the corresponding hole. The filling height of the concrete is greater than the height of the anchor bolt nut. The fifth step is to fix the anchor bolts after the concrete filling is completed; The sixth step involves manually verifying the anchoring force between the anchor rod and the concrete, the position of the anchor rod, and the fixing point. Step 7: After the anchor bolts are fixed, backfill the ultra-deep foundation pit. The specific steps for testing the stability of the supporting structure to determine its ability to stably support the ultra-deep foundation pit before removing the steel plate include: The first step is for the operators to classify the supporting structure into different levels based on the BIM model of the ultra-deep foundation pit and its surrounding environment, and obtain the first weight allocation result. The second step involves the operator obtaining a second weight allocation result based on the force and swaying conditions of the support structure in the actual environment. The third step involves the operator performing voxelization of the BIM model of the ultra-deep foundation pit and its surrounding environment based on a clustering algorithm to obtain the support structure level analysis results and the third weight allocation results. The fourth step is to obtain the stability evaluation result of the support structure based on the first weight allocation result, the second weight allocation result, and the third weight allocation result. Fifth, after assessing the stability of the supporting structure and confirming that it can stably support the ultra-deep foundation pit, the steel plate is removed.

2. The construction method of a concrete support servo system for ultra-deep foundation pits adjacent to subways according to claim 1, characterized in that, The multi-layer reinforced concrete support servo reaction structure is designed with a distributed hydraulic control mode, including a servo support main control cabinet, multiple servo support components, multiple small hydraulic pump stations, and multiple double mechanical lock frames. The multiple small hydraulic pump stations are respectively installed in the support head assembly of the servo support components, forming a distributed power unit. The distributed power unit is connected in series with the servo support main control cabinet through an RS485 signal line and a 48V power line. The multiple double mechanical lock frames are respectively configured on the support head of each servo support component to improve the safety redundancy of the support axis force servo system.

3. The construction method of a concrete support servo system for ultra-deep foundation pits adjacent to subways according to claim 2, characterized in that, A small hydraulic pump station is installed separately in the support head assembly of each servo support to form a distributed power unit. The distributed power unit is connected in series with the main control cabinet of the servo support through an RS485 signal line and a 48V power line. A double mechanical lock frame is configured on the support head of each servo support to improve the safety redundancy of the support axis force servo system.

4. The construction method of a concrete support servo system for ultra-deep foundation pits adjacent to subways according to claim 3, characterized in that, The specific steps of filling concrete at the position of the anchor rod and the corresponding hole after confirming stability, wherein the filling height of the concrete is greater than the height of the anchor rod nut, include: The first step is to insert the concrete-filled pipe into the bottom of the anchor bolt installation hole; The second step is to gradually fill concrete between the anchor rod and the hole from bottom to top; The third step involves continuously vibrating the concrete during the filling process to dislodge air bubbles from the concrete between the anchor rod and the hole, ensuring the compactness of the filled concrete.

5. A construction method for a concrete support servo system adjacent to an ultra-deep foundation pit near a subway, as described in claim 4, is characterized in that... The specific steps of fixing the steel plate inside the ultra-deep foundation pit, wherein the steel plate is arranged around the anchor bolt, include: The first step is to dig an installation pit around the anchor bolt; The second step is to perform low-temperature stretching on the steel plate according to the curvature and radius of the mounting pit to form a steel plate with the same curvature and radius as the mounting pit. The third step is to fix the steel plate in the installation pit so that the steel plate surrounds the anchor rod.

6. The construction method of a concrete support servo system for ultra-deep foundation pits adjacent to subways according to claim 5, characterized in that, The step of performing low-temperature stretching on the steel plate according to the curvature and radius of the mounting pit to form a steel plate with the same curvature and radius as the mounting pit includes: The first step is recrystallization treatment. The steel plate is cut into appropriate sizes and placed in a reducing protective atmosphere for heat treatment. The temperature of the heat treatment is 700-800℃ and the holding time is 30-60 minutes. Then it is cooled to room temperature in the air. The second step is low-temperature hot stretching treatment, in which the recrystallized steel plate is subjected to hot stretching deformation with different degrees of bending at low temperature. The hot stretching deformation temperature is 300-400℃, the elongation of the hot stretching deformation is 10-30%, and the stretching speed of the hot stretching deformation is 1-5mm / min. Then it is cooled to room temperature in air. The third step is high-temperature recovery treatment. The steel plate after low-temperature hot stretching is placed in a reducing protective atmosphere and heated at high temperature. The high-temperature heating temperature is 500-600℃ and the holding time is 1-2 hours. The fourth step is solution treatment. The steel plate after high-temperature recovery treatment is further heated for solution treatment. The heating temperature is 1000-1100 ℃, and the holding time is 10-30 min. The fifth step is quenching. The steel plate after solution treatment is quenched by rapid cooling to obtain a steel plate with the same arc and curvature as the mounting pit.

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