Deep and large foundation pit permanent enclosure and modular partition steel support structure and digital construction method

Abstract

This invention relates to the field of foundation pit support construction technology, proposing a permanent retaining structure and modular zoned steel bracing structure for deep and large foundation pits, along with a digital and intelligent construction method. The structure includes a retaining structure and a supporting structure. The retaining structure comprises multiple composite steel piles and concrete walls, with the composite steel piles connected to form the steel walls. The supporting structure includes multiple rigid platforms and steel supports. Each rigid platform includes horizontal supports and vertical columns. Multiple layers of horizontal supports are connected and supported by vertical columns, and the top of each horizontal support is equipped with an octagonal trestle plate. The horizontal supports of two adjacent rigid platforms are connected by steel supports, and the horizontal supports of the rigid platform closest to the retaining structure are connected to the composite steel piles by steel supports. The multiple rigid platforms and steel supports divide the foundation pit into multiple construction zones. This invention provides a high degree of integration between the retaining structure and the main structure, and a deep and large foundation pit all-steel support structure and monitoring method that facilitates easy deformation monitoring and control, achieving safe, efficient, green, and intelligent construction of deep and large foundation pit projects.

Description

Technical Field

[0001] This invention relates to the field of foundation pit support construction technology, specifically to permanent retaining structures and modular partitioned steel bracing structures for deep and large foundation pits, as well as intelligent construction methods. Background Technology

[0002] As underground space development moves towards deeper, larger-scale, and higher-density projects, ultra-large-scale deep foundation pit engineering has become commonplace. These projects not only face extremely stringent requirements for deformation control and safety stability but also bear immense pressure to shorten construction periods, control costs, and reduce environmental impact. Although foundation pit support technology has made some progress in supporting components and node connections, the existing technological system still has significant gaps and shortcomings, hindering the upgrading of foundation pit engineering towards high quality, industrialization, and sustainability.

[0003] Traditional foundation pit support systems often employ a hybrid system combining cast-in-place concrete piles and internal bracing. In this system, the retaining structure is often a temporary design with low integration with the main structure, resulting in resource waste. Furthermore, the support members are mostly independent compression members, lacking effective rigid connections, leading to insufficient overall system stiffness.

[0004] Furthermore, since the force is often transferred between the retaining structure and the support through concrete girders, there is a significant time lag effect and energy dissipation in the force transmission, making it difficult to achieve deep coordinated force sharing between temporary support and permanent structure. This limits the accuracy of deformation control. At the same time, current foundation pit monitoring suffers from problems such as low monitoring frequency, data lag, and susceptibility to external environmental interference. Moreover, most of the existing monitoring data are isolated displacement or strain values, lacking effective multi-source heterogeneous data fusion algorithms. This makes it impossible to achieve real-time correction and accurate prediction of structural deformation, which is insufficient to meet the needs of modern digital construction for high-frequency and high-precision safety management.

[0005] Therefore, there is an urgent need for a deep and large foundation pit all-steel support structure with high integration between the retaining structure and the main structure, and an intelligent construction method for easy deformation monitoring and control, so as to achieve safe, efficient, green and intelligent construction of deep and large foundation pit projects. Summary of the Invention

[0006] To address the problems existing in the background technology, this invention proposes a permanent retaining structure and modular partitioned steel bracing structure for deep and large foundation pits, including a retaining structure and a supporting structure. The retaining structure includes multiple combined steel piles and concrete walls, with the multiple combined steel piles connected to form a steel wall, which is fixed within the concrete wall. The supporting structure includes multiple rigid platforms and steel supports. The rigid platform includes horizontal supports and vertical columns. The horizontal supports are multi-layered, and the multiple layers of horizontal supports are connected and supported by vertical columns. An octagonal trestle plate is fixed to the top of the horizontal supports. Multiple rigid platforms are provided within the foundation pit.

[0007] The horizontal supports of two adjacent rigid platforms are connected by steel supports. The horizontal supports of the rigid platform near the retaining structure are connected to the composite steel piles by steel supports. Multiple rigid platforms and steel supports divide the foundation pit into multiple construction zones.

[0008] Preferably, the horizontal support includes multiple transverse supports and multiple longitudinal supports, which are orthogonally connected to form an octagonal grid structure. The ends of the transverse supports, the ends of the longitudinal supports, and the intersections of the longitudinal and transverse supports are respectively connected to vertical columns. The ends of adjacent longitudinal and transverse supports are connected by diagonal supports.

[0009] Preferably, the steel support includes horizontal steel supports and vertical columns.

[0010] Preferably, the steel supports, transverse supports, longitudinal supports, diagonal supports, and vertical columns are all H-beams.

[0011] Preferably, the composite steel pile includes a main pile and an auxiliary pile. The auxiliary pile includes two AZ-type steel sheet piles, and the main pile includes two HZ-type steel sheets. One end of one HZ-type steel sheet of the main pile is connected to one end of one AZ-type steel sheet pile via an RZU-type locking buckle. One end of the other HZ-type steel sheet of the main pile is connected to one end of another AZ-type steel sheet pile via an RZU-type locking buckle. The ends of the two AZ-type steel sheet piles that are not connected to the main pile are connected via Larsen locking buckles. The end of the HZ-type steel sheet away from the auxiliary pile is fixed with an RZD-type locking buckle. The HZ-type steel sheets of two adjacent composite steel piles are connected via RZD-type locking buckles.

[0012] Preferably, the steel support is connected to the horizontal support of the rigid platform and the main pile of the composite steel pile by bolts.

[0013] The digital construction method for permanent retaining and modular partitioned steel bracing structures of deep foundation pits includes the following steps: S1. Carry out the integrated construction of the enclosure structure and the support structure. Before the construction of the support structure, lay distributed optical fibers on the inner side of the upper and lower flanges of the H-beam, and the distributed optical fibers are arranged along the axial direction of the H-beam. S2, Sensor Deployment S2.1 Measurement point layout Two to three GNSS reference stations are set up on stable foundations outside the deformation range of the foundation pit, and a fixed uninterruptible power supply is used for power supply. One main GNSS terminal is deployed at the geometric center of the octagonal trestle plate; Two auxiliary GNSS terminals are symmetrically arranged along the long axis of the octagonal trestle deck at the edge of the deck surface. S2.2 Bracket Installation Brackets are installed along the edge of the octagonal trestle panel, and the bracket bases are fastened to the octagonal trestle panel with bolts. S2.3 Terminal Setup Mount the GNSS antenna on top of the support frame; S3. Perform data processing and algorithm integration. S3.1 Initial coordinate calibration Before excavation of earthwork in different sections and blocks, the initial coordinates of the main GNSS terminal in a static state are collected. Establish the absolute displacement reference for this partition; S3.2, Data Fusion S3.2.1 When installing diagonal supports to form an octagonal shape with horizontal supports, distributed optical fibers collect strain data of H-beams in real time. S3.2.2, Set the path parameter along the axis of the H-beam as S, where The optical fiber is laid along path S to collect micro-strain data in real time. ; The strain difference between the upper and lower flanges of the H-beam was measured using distributed optical fiber. Calculate the curvature of the H-beam at any position along path S. :

[0014] in: , The measured strains are those of the upper and lower flanges, respectively; h is the cross-sectional height of the H-beam. S3.2.3, Regarding curvature By performing an integral, the rotation angle function of the H-beam along the axial direction can be obtained. ; S3.2.4. Obtain the absolute displacement of the rigid platform through the main GNSS terminal, use it as a constraint term in the deflection equation, and perform a second integral on the rotation angle function to obtain the deflection equation:

[0015] in: The integration constant is 1, representing the initial rotation angle / slope; The integral constant is 2, representing the initial displacement; S3.2.5. Using data acquired by the GNSS terminal, solve for the unknown constants in the above equations to eliminate the initial error of fiber integration: S3.2.5.1, Set the absolute vertical displacement measured by the main GNSS terminal as... At S=0, let Thus determine ; S3.2.5.2 Utilizing observations from two auxiliary GNSS terminals and displacement difference Calculate the overall tilt angle of the rigid platform. ,make This determines the initial slope of the integral. .

[0016] S4, Kalman Filter (EKF) Algorithm Correction S4.1 Using fiber optic strain data as a prediction of the supporting structure's condition. Using equations S3.2.2 and S3.2.4, the continuous deformation curve of the support structure is derived: ; S4.2. Use the absolute coordinates measured by the main GNSS terminal and the auxiliary GNSS terminal as the observation values. ; S4.3 Calculate the residual between the predicted continuous deformation curve and the GNSS terminal observations using the EKF algorithm. : When fiber integration produces a deviation of more than 1 mm due to ambient temperature or accumulated calculations, i.e., residual... When mm, the algorithm automatically adjusts. The algorithm calculates the optimal displacement estimate at each time step. :

[0017]

[0018] in, For the observation transformation matrix, To predict the displacement at time k based on the optical fiber physical model; For Kalman gain, ,when When the value is close to 1, it indicates that the system trusts satellite signals more; when... When the value is close to 0, it indicates that the system trusts the fiber optic signal more. S5, Decision Making and Loop Decisions S5.1 Optimal displacement estimate after fusion based on the output of step S4 Real-time comparison of the settlement value at the center of the octagonal trestle bridge and the axial force change of the vertical H-beams connected to it; If vertical H-beam settlement is found to cause the corresponding horizontal H-beam stress release rate to exceed 15%, on-site personnel need to develop an adjustment plan to compensate for axial force. Stress release rate = ; Where F is the design preload axial force. This refers to the real-time axial force. S5.2 During the dismantling phase of the supporting structure, the residual deformation energy of the H-beam is calculated using the strain history recorded by distributed optical fibers throughout the entire process. :

[0019] in, This represents the real-time stress inside the H-beam at time t; This represents the rate of plastic strain generated in the H-beam at time t. If the H-beam remains in the elastic stage, then This indicates that the H-beam is intact and belongs to the category of recyclable components; if If the fatigue threshold is less than the set material fatigue threshold, the H-beam and octagonal trestle plate are determined to be recyclable components, assigned a unique digital ID, and directly allocated to the next construction zone for reuse; if When the fatigue threshold set by the material is exceeded, it is considered a non-cyclic component.

[0020] Preferably, the method for setting up the distributed optical fiber includes the following steps: A1.1 Cut into grooves After the H-beam is finished, a laser beam is used to continuously pulse-cut the inner surface of the upper and lower flanges of the H-beam near the corner of the web to form a concave U-shaped groove. A1.2 Tunnel Bottom Treatment and Fiber Embedding After cutting, remove the slag from the bottom and edges of the tank, and then polish it to ensure that the tank walls are smooth. The distributed optical fiber is laid flat on the bottom of the laser-formed U-shaped groove; High-strength weather-resistant epoxy resin is injected into the tank, completely covering the distributed optical fibers and tightly bonding them to the tank wall.

[0021] Preferably, the GNSS reference station is located on the ground at a distance of twice the depth of the pit; the support height is not less than 1.8m.

[0022] The beneficial effects of this invention are as follows: 1. Large-section composite steel piles are used as the permanent retaining wall for continuous walls, and a rigid platform is used as the resource hub. The load supported is effectively transferred to the permanent retaining structure through the nodes of the rigid platform, so that the permanent structure participates in the stress during the construction stage. This concentrates the horizontal support stress of the foundation pit, enhances the overall torsional and heave resistance of the foundation pit, and avoids the problems of functional duplication and resource waste between temporary and permanent structures in the traditional mode.

[0023] 2. Large-section composite steel piles are used as the permanent retaining structure of the continuous wall. The support structure can be completely dismantled, repaired in categories, and reused multiple times after use, replacing the on-site pouring process of traditional reinforced concrete support, realizing the permanent construction of deep and large foundation pits and the new green construction of standard steel support.

[0024] 3. Fiber optic sensors are deployed at key support steel sections to collect strain data in real time. Combined with GNSS satellite positioning technology, the displacement and rotation of the core hubs in the support system are captured, realizing digital perception of the complex support system and providing data support and decision-making basis for intelligent monitoring of the entire life cycle of the project.

[0025] This invention features a high degree of integration between the retaining structure and the main structure, making full use of the supporting effect of multiple rows of steel beams on the soil, as well as the construction traffic formed by rigid platforms, steel beam supports, and trestle plates. It has formed a fully recoverable, multi-cycle ultra-large-scale foundation pit all-steel support structure and monitoring method, which improves construction efficiency, shortens the total construction period, and makes the project progress, quality, and safety risks highly controllable, realizing safe, efficient, green, and intelligent construction of deep and large foundation pit projects. Attached Figure Description

[0026] Figure 1 This is a top view of the support structure of the present invention; Figure 2 This is a schematic diagram of the rigid platform structure of the present invention; Figure 3 This is a schematic diagram showing the location of the concave U-shaped groove of the present invention; Figure 4 This is a schematic diagram of the H-shaped steel structure of the present invention; Figure 5 This is a schematic diagram of the combined steel pile structure of the present invention; Figure 6 This is a schematic diagram of the monitoring method of the present invention.

[0027] The following are the labels in the diagram: 1. H-beam; 2. Lower flange; 3. U-shaped channel; 4. Rigid platform; 41. Lateral support; 42. Longitudinal support; 43. Vertical column; 44. Diagonal support; 5. Construction zone; 6. HZ-shaped steel plate; 7. AZ-shaped steel sheet pile. Detailed Implementation

[0028] To make the present invention clearer and more understandable, the technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the given embodiments are only one or more of the implementation methods and do not represent all embodiments.

[0029] In this article, terms such as "inner," "outer," "upper," and "lower" are established based on the positional relationships shown in the attached drawings. Depending on the attached drawings, the corresponding positional relationships may also change. Therefore, they should not be interpreted as an absolute limitation on the scope of protection.

[0030] Combined with appendix Figure 1 -Appendix Figure 5 The permanent retaining structure and modular partitioned steel bracing structure for deep foundation pits includes a retaining structure and a supporting structure. The retaining structure includes multiple combined steel piles and concrete walls. The multiple combined steel piles are connected to form a steel wall, which is fixed inside the concrete wall. The supporting structure includes multiple rigid platforms 4 and steel supports. The rigid platform 4 includes horizontal supports and vertical columns 43. The horizontal supports are multi-layered, and the multi-layered horizontal supports are connected and supported by vertical columns 43. An octagonal trestle plate is fixed to the top of the horizontal supports. Multiple rigid platforms 4 are provided inside the foundation pit. The horizontal supports of two adjacent rigid platforms 4 are connected by steel supports. The horizontal supports of the rigid platform near the retaining structure are connected to the composite steel piles by steel supports. Multiple rigid platforms 4 and steel supports divide the foundation pit into multiple construction zones 5.

[0031] Specifically, the horizontal support includes multiple transverse supports 41 and multiple longitudinal supports 42, which are orthogonally connected to form an octagonal grid structure. Vertical columns 43 are connected to the ends of the transverse supports 41, the ends of the longitudinal supports 42, and the intersections of the longitudinal supports 42 and transverse supports 41. Adjacent longitudinal supports 42 and transverse supports 41 are connected by diagonal supports 44. More specifically, the transverse supports 41, longitudinal supports 42, diagonal supports 44, and vertical columns 43 are connected by high-strength bolts; the horizontal support is also connected to the octagonal trestle plate by high-strength bolts.

[0032] Specifically, the steel support includes horizontal steel supports and vertical columns. The horizontal steel supports connect two adjacent horizontal supports, or the horizontal supports connect to the combined steel piles; the number of layers of the horizontal steel supports is the same as that of the horizontal supports, and the vertical columns are connected to the horizontal steel supports to support them.

[0033] Specifically, the steel supports, transverse supports 41, longitudinal supports 42, diagonal supports 44, and vertical columns 43 are all H-beams 1.

[0034] Specifically, the composite steel pile includes a main pile and an auxiliary pile. The auxiliary pile includes two AZ-type steel sheet piles 7, and the main pile includes two HZ-type steel plates 6. One end of one HZ-type steel plate 6 of the main pile is connected to one end of one AZ-type steel sheet pile 7 through an RZU-type lock. One end of the other HZ-type steel plate 6 of the main pile is connected to one end of another AZ-type steel sheet pile 7 through an RZU-type lock. The ends of the two AZ-type steel sheet piles 7 that are not connected to the main pile are connected through Larsen locks. The end of the HZ-type steel plate 6 away from the auxiliary pile is fixed with an RZD-type lock. The HZ-type steel plates 6 of two adjacent composite steel piles are connected through RZD-type locks.

[0035] Specifically, the steel support, the horizontal support of the rigid platform 4, and the main pile of the composite steel pile are all connected by bolts. The bolts are high-strength bolts.

[0036] The digital construction method for permanent retaining and modular partitioned steel bracing structures of deep foundation pits includes the following steps: S1. Carry out the integrated construction of the enclosure structure and the support structure. Before the construction of the support structure, lay distributed optical fibers on the inner side of the upper and lower flanges 2 of the H-beam 1 respectively. The distributed optical fibers are arranged along the axial direction of the H-beam 1. Specifically, step S1 includes: S1.1 Construction of the Enclosure Structure S1.1.1 Surveying and Setting Out and Guide Wall Construction Measure and lay out the lines according to the design drawings, and set up guide walls at the locations of the underground structure's outer walls; S1.1.2 Trenching Construction The grab bucket trenching equipment is used to trench along the guide wall, while the wall protection mud is injected to form a rectangular bare trench with a flat wall and precise dimensions. S1.1.3, Guide frame installation A guide frame is installed at the opening of the trench after the trench is completed, and the guide frame is matched with the cross-sectional dimensions of the composite steel pile; S1.1.4, Sinking of Composite Steel Piles The prefabricated composite steel piles are hoisted into the guide frame, and under the guidance of the guide frame, the composite steel piles are sunk to the bottom of the trench to the design elevation; S1.1.5, Continuous splicing into a wall Align and sink the RZD type locks of adjacent composite steel piles so that the locks automatically engage, thereby achieving continuous splicing between composite steel piles to form a steel wall, and thus forming a continuous all-steel underground structure exterior wall. S1.1.6, Backfilling and Waterstop Reinforcement in the Trench After the composite steel piles are driven in, grout is injected into the trench and behind the steel wall formed by the composite steel piles through the pre-set grouting pipes to fill the gaps and enhance the wall's load-bearing capacity and water-stopping performance; at the same time, water-stopping material is injected into each interlock to improve the seepage prevention performance of the interlock parts. S1.1.7 Formation of a permanent structure After the grouting material has cured, the underground structure exterior wall formed by the composite steel piles serves as the foundation pit retaining structure. S1.2 Construction of supporting structures and excavation of foundation pit S1.2.1 According to the construction organization schedule, based on the construction scope of the foundation pit and the area of ​​construction zone 5, several horizontal partition lines are set along the horizontal direction of the foundation pit, and several vertical partition lines are set along the longitudinal direction of the foundation pit. The horizontal and vertical partition lines divide the entire foundation pit construction scope into several construction zones 5. S1.2.2 The intersection of the horizontal and vertical zoning lines of the foundation pit is the construction location of the rigid platform 4. That is, each construction zone 5 is enclosed by four rigid platforms 4 and steel supports connecting the four rigid platforms 4. S1.2.2 Build a rigid platform 4 at at least one construction location. Two adjacent rigid platforms 4 are connected by the first layer of steel support. The octagonal trestle plate on the top of the rigid platform 4 serves as the passage and operation channel for excavators and dump trucks. S1.2.3. Construct a rigid platform 4 and steel supports to divide the construction zone 5; after dividing the construction zone 5, excavate the first layer of earthwork in the construction zone 5; at least one construction zone 5 shall be excavated during the excavation. S1.2.4 After the first layer of earthwork excavation is completed, a second steel support is erected between the two adjacent rigid platforms 4 corresponding to the excavation area; S1.2.5, Excavate the second layer of soil; S1.2.6 Repeat steps S1.2.1-S1.2.5 to excavate construction zone 5 to the foundation, forming a rigid platform 4 and an independent space around it with multi-layer steel support. S1.2.7 Complete the construction of the foundation structure and main structure within the excavation pit in an independent space; S1.2.8 After the construction of each zone is completed, remove the rigid platform 4 and the steel support; After the removal of S1.2.9, rigid platform 4, and steel support, a foundation pit space is left, and the construction of the foundation structure and main structure is carried out in the foundation pit space.

[0037] More specifically, the distributed optical fiber is preferentially laid on the H-beam 1 with the largest span (i.e., the largest slenderness ratio) in each zone, the H-beam 1 arranged in conjunction with the main GNSS terminal (i.e., connecting the geometric center of the octagonal trestle plate), and the H-beam 1 connected to the auxiliary GNSS terminal.

[0038] S2, Sensor Deployment S2.1 Measurement point layout Two to three GNSS reference stations are set up on stable foundations outside the deformation range of the foundation pit. They are powered by a fixed uninterruptible power supply. The GNSS reference stations provide real-time differential correction signals (RTK) to the monitoring points (GNSS terminals) inside the pit. A main GNSS terminal is deployed at the geometric center of the octagonal trestle deck, and the observation value of this point in the construction coordinate system is set as... It reflects the settlement and horizontal displacement of the vertical column 43, and serves as the absolute displacement reference for the rigid platform 4 and its vertical column 43. Two auxiliary GNSS terminals are symmetrically positioned along the long axis of the octagonal trestle platform, at opposite corners of the platform. The observation values ​​from the two auxiliary GNSS terminals are as follows: and Used to capture the torsion angle of rigid platform 4 in real time. ; S2.2 Bracket Installation A bracket is installed on the edge of the octagonal trestle plate, and the bracket base is fastened to the octagonal trestle plate with bolts; specifically, the bracket is a tripod-type protective support frame. S2.3 Terminal Setup Mount the GNSS antenna on top of the support frame; S3. Perform data processing and algorithm integration. S3.1 Initial coordinate calibration Before excavation of earthwork in different sections and blocks, the initial coordinates of the main GNSS terminal in a static state are collected. Establish the absolute displacement benchmark for construction zone 5; S3.2, Data Fusion S3.2.1 When installing the diagonal support 44 to form an octagonal horizontal support, the distributed optical fiber collects the strain data of the H-beam 1 in real time. S3.2.2, Set the path parameter along the axis of H-beam 1 as S, where The optical fiber is laid along path S to collect micro-strain data in real time. ; The strain difference between the upper and lower flanges 2 of the H-beam 1 was measured using distributed optical fiber. Calculate the curvature of H-beam 1 at any position along path S. :

[0039] in: , 2 represents the measured strain of the upper flange and the lower flange 2, respectively; h is the cross-sectional height of H-beam 1; S3.2.3, Regarding curvature By performing an integral, we obtain the rotation angle function of H-beam 1 along the axial direction. ; S3.2.4. Obtain the absolute displacement of the rigid platform 4 through the main GNSS terminal, use it as a constraint term in the deflection (displacement) equation, and perform a second integral on the rotation angle function to obtain the deflection (displacement) equation:

[0040] in: The integration constant is 1, representing the initial rotation angle / slope; The integral constant is 2, representing the initial displacement; S3.2.5. Using data acquired by the GNSS terminal, solve for the unknown constants in the above equations to eliminate the initial error of fiber integration: S3.2.5.1, Set the absolute vertical displacement measured by the main GNSS terminal as... At S=0, let Thus determine ; S3.2.5.2 Utilizing observations from two auxiliary GNSS terminals and displacement difference Calculate the overall tilt angle of rigid platform 4. ,make This determines the initial slope of the integral. .

[0041] S4, Kalman Filter (EKF) Algorithm Correction S4.1 Using fiber optic strain data as a prediction of the supporting structure's condition. Using equations S3.2.2 and S3.2.4, the continuous deformation curve of the support structure is derived: ; S4.2. Use the absolute coordinates measured by the main GNSS terminal and the auxiliary GNSS terminal as the observation values. ; S4.3 Calculate the residual between the predicted continuous deformation curve and the GNSS terminal observations using the EKF algorithm. : When fiber integration produces a deviation of more than 1 mm due to ambient temperature or accumulated calculations, i.e., residual... When mm, the algorithm automatically adjusts. The algorithm calculates the optimal displacement estimate at each time step. :

[0042]

[0043] in, For the observation transformation matrix, To predict the displacement at time k based on the optical fiber physical model; For Kalman gain, ,when When the value is close to 1, it indicates that the system trusts satellite signals more; when... When the value is close to 0, it indicates that the system trusts the fiber optic signal more. S5, Decision Making and Loop Decisions S5.1 Optimal displacement estimate after fusion based on the output of step S4 Real-time comparison of the settlement value at the center of the octagonal trestle bridge and the axial force change of the vertical H-beam 1 connected to it; If the settlement of vertical H-beam 1 causes the stress release rate of the corresponding horizontal H-beam 1 to exceed 15%, on-site personnel need to develop an adjustment plan to compensate for axial force. Stress release rate = ; Where F is the design preload axial force. This refers to the real-time axial force. S5.2 During the dismantling phase of the supporting structure, the residual deformation energy of H-beam 1 is calculated using the strain history recorded by distributed optical fibers throughout the entire process. :

[0044] in, This represents the real-time stress inside H-beam 1 at time t; This represents the rate of plastic strain generated in H-beam 1 at time t; If H-beam 1 remains in the elastic stage, then This indicates that H-beam 1 is intact and belongs to the category of recyclable components; if If the fatigue threshold is less than the set material fatigue threshold, the H-beam 1 and the octagonal trestle plate are determined to be recyclable components, assigned a unique digital identity ID, and directly allocated to the next construction zone 5 for reuse; if When the fatigue threshold set by the material is exceeded, it is considered a non-cyclic component.

[0045] Specifically, this includes a method for setting up the distributed optical fiber, the steps of which are as follows: A1.1 Cut into grooves After the H-beam 1 is finished, a high-power laser beam is used to continuously pulse-cut the inner surface of the upper flange and lower flange 2 of the H-beam 1 near the corner of the web to form a concave U-shaped groove 3. A1.2 Tunnel Bottom Treatment and Fiber Embedding After cutting, remove the slag from the bottom and edges of the tank, and then polish it to ensure that the tank walls are smooth. The distributed optical fiber is laid flat on the bottom of the laser-formed U-shaped groove 3; High-strength weather-resistant epoxy resin is injected into the tank, completely covering the distributed optical fibers and tightly bonding them with the tank wall. This allows the optical fibers and the steel profile to form a deformable community, ensuring that the optical fibers are not physically damaged during assembly and recycling.

[0046] More specifically, the U-shaped groove 3 is 5-8mm from the edge of the flange, 6-8mm wide, and 4-6mm deep. In the node connection area, the groove depth is increased by 1.0mm to enhance protection.

[0047] Specifically, the GNSS reference station is located on the ground at a distance of twice the depth of the excavation pit; the support height is not less than 1.8m to ensure that the tangential obstruction angle of the satellite signal remains within 15° when the excavation vehicle passes over the octagonal trestle bridge.

[0048] Although embodiments of the invention have been shown and described, those skilled in the art will be able to make various changes, modifications, substitutions and alterations to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A deep and large foundation pit permanent enclosure and modular partition steel support structure, characterized in that: The enclosure structure includes a retaining structure and a supporting structure. The retaining structure includes multiple composite steel piles and concrete walls. The multiple composite steel piles are connected to form a steel wall. The steel wall is fixed inside the concrete wall. The supporting structure includes multiple rigid platforms (4) and steel supports. The rigid platform (4) includes horizontal supports and vertical columns (43). The horizontal supports are provided in multiple layers. The multiple layers of horizontal supports are connected and supported by vertical columns (43). An octagonal trestle plate is fixed on the top of the horizontal supports. Multiple rigid platforms (4) are provided in the foundation pit. The horizontal supports of two adjacent rigid platforms (4) are connected by steel supports. The horizontal supports of the rigid platform (4) close to the retaining structure are connected to the composite steel piles by steel supports. Multiple rigid platforms (4) and steel supports divide the foundation pit into multiple construction zones (5).

2. The deep and large foundation pit permanent enclosure and modular partition steel bracing structure according to claim 1, characterized in that: The horizontal support includes multiple transverse supports (41) and multiple longitudinal supports (42). The multiple transverse supports (41) and longitudinal supports (42) are orthogonally connected to form an octagonal grid structure. The ends of the transverse supports (41), the ends of the longitudinal supports (42), and the intersection of the longitudinal supports (42) and the transverse supports (41) are respectively connected to vertical columns (43). The ends of adjacent longitudinal supports (42) and transverse supports (41) are connected by diagonal supports (44).

3. The permanent retaining structure and modular partitioned steel bracing structure for deep and large foundation pits according to claim 2, characterized in that: The steel support includes horizontal steel supports and vertical columns.

4. The permanent retaining structure and modular partitioned steel bracing structure for deep and large foundation pits according to claim 3, characterized in that: The steel supports, transverse supports (41), longitudinal supports (42), diagonal supports (44), and vertical columns (43) are all H-beams (1).

5. The permanent retaining structure and modular partitioned steel bracing structure for deep and large foundation pits according to claim 4, characterized in that: The composite steel pile includes a main pile and an auxiliary pile. The auxiliary pile includes two AZ-type steel sheet piles (7). The main pile includes two HZ-type steel plates (6). One end of one of the HZ-type steel plates (6) of the main pile is connected to one end of one of the AZ-type steel sheet piles (7) through an RZU-type lock. One end of the other HZ-type steel plate (6) of the main pile is connected to one end of another AZ-type steel sheet pile (7) through an RZU-type lock. The ends of the two AZ-type steel sheet piles (7) that are not connected to the main pile are connected through Larsen locks. The end of the HZ-type steel plate (6) away from the auxiliary pile is fixed with an RZD-type lock. The HZ-type steel plates (6) of two adjacent composite steel piles are connected through RZD-type locks.

6. The permanent retaining structure and modular partitioned steel bracing structure for deep and large foundation pits according to claim 5, characterized in that: The horizontal support of the steel profile support and the rigid platform (4) and the main pile of the composite steel profile pile are all connected by bolts.

7. A digital and intelligent construction method for permanent retaining and modular partitioned steel bracing structures for deep and large foundation pits, implemented based on the permanent retaining and modular partitioned steel bracing structures for deep and large foundation pits as described in claim 6, characterized in that... Includes the following steps: S1. Carry out the integrated construction of the enclosure structure and the support structure. Before the construction of the support structure, distribute optical fibers are laid on the inner side of the upper and lower flanges (2) of the H-beam (1). The distributed optical fibers are arranged along the axial direction of the H-beam (1). S2, Sensor Deployment S2.1 Measurement point layout Two to three GNSS reference stations are set up on stable foundations outside the deformation range of the foundation pit, and a fixed uninterruptible power supply is used for power supply. One main GNSS terminal is deployed at the geometric center of the octagonal trestle plate; Two auxiliary GNSS terminals are symmetrically arranged along the long axis of the octagonal trestle deck at the edge of the deck surface. S2.2 Bracket Installation Brackets are installed along the edge of the octagonal trestle panel, and the bracket bases are fastened to the octagonal trestle panel with bolts. S2.3 Terminal Setup Mount the GNSS antenna on top of the support frame; S3. Perform data processing and algorithm integration. S3.1 Initial coordinate calibration Before excavation of earthwork in different sections and blocks, the initial coordinates of the main GNSS terminal in a static state are collected. Establish the absolute displacement reference for this partition; S3.2, Data Fusion S3.2.1 When installing the diagonal support (44) to form an octagonal horizontal support, the distributed optical fiber collects the strain data of the H-beam (1) in real time. S3.2.2, Set the path parameter along the axis of H-beam (1) as S, where The optical fiber is laid along path S to collect micro-strain data in real time. ; The strain difference between the upper and lower flanges (2) of the H-beam (1) was measured using distributed optical fiber. Calculate the curvature of the H-beam (1) at any position along path S. : in: , The measured strains of the upper flange and lower flange (2) are respectively; h is the cross-sectional height of the H-beam (1); S3.2.3, Regarding curvature By performing an integral, we obtain the rotation angle function of the H-beam (1) along the axial direction. ; S3.2.

4. Obtain the absolute displacement of the rigid platform (4) through the main GNSS terminal, use it as a constraint term in the deflection equation, and perform a second integral on the rotation angle function to obtain the deflection equation: in: The integration constant is 1, representing the initial rotation angle / slope; The integral constant is 2, representing the initial displacement; S3.2.

5. Using data acquired by the GNSS terminal, solve for the unknown constants in the above equations to eliminate the initial error of fiber integration: S3.2.5.1, Set the absolute vertical displacement measured by the main GNSS terminal as... At S=0, let Thus determine ; S3.2.5.2 Utilizing observations from two auxiliary GNSS terminals and displacement difference Calculate the overall tilt angle of the rigid platform (4). ,make This determines the initial slope of the integral. ; S4, Kalman filter algorithm correction S4.1 Using fiber optic strain data as a prediction of the supporting structure's condition. Using equations S3.2.2 and S3.2.4, the continuous deformation curve of the support structure is derived: ； S4.

2. Use the absolute coordinates measured by the main GNSS terminal and the auxiliary GNSS terminal as the observation values. ; S4.3 Calculate the residual between the predicted continuous deformation curve and the GNSS terminal observations using the EKF algorithm. : When fiber integration produces a deviation of more than 1 mm due to ambient temperature or accumulated calculations, i.e., residual... When mm, the algorithm automatically adjusts. The algorithm calculates the optimal displacement estimate at each time step. : in, For the observation transformation matrix, To predict the displacement at time k based on the optical fiber physical model; For Kalman gain, ,when When the value is close to 1, it indicates that the system trusts satellite signals more; when... A value close to 0 indicates that the system trusts the fiber optic signal more. S5, Decision Making and Loop Decisions S5.1 Optimal displacement estimate after fusion based on the output of step S4 Real-time comparison of the settlement value at the center of the octagonal trestle bridge and the axial force change of the vertical H-beam (1) connected to it; If the settlement of the vertical H-beam (1) causes the stress release rate of the corresponding horizontal H-beam (1) to exceed 15%, the on-site personnel need to make an adjustment plan to compensate for the axial force. The stress release rate = ; Where F is the design preload axial force. This refers to the real-time axial force. S5.2 During the dismantling of the supporting structure, the residual deformation energy of the H-beam (1) is calculated using the strain history recorded by distributed optical fibers throughout the entire process. : in, This represents the real-time stress inside the H-beam (1) at time t; The value represents the rate of plastic strain generated in the H-beam (1) at time t; If the H-beam (1) remains in the elastic stage, then This indicates that the H-beam (1) is intact and belongs to the category of recyclable components; if If the fatigue threshold is less than the material's set value, the H-beam (1) and the octagonal trestle are determined to be recyclable components, assigned a unique digital ID, and directly allocated to the next construction zone (5) for reuse; if When the fatigue threshold set by the material is exceeded, it is considered a non-cyclic component.

8. The intelligent construction method for permanent retaining and modular partitioned steel bracing structure of deep foundation pits according to claim 7, characterized in that, The method for setting up the distributed optical fiber includes the following steps: A1.1 Cut into grooves After the H-beam (1) is finished, a laser beam is used to continuously pulse-cut the inner surface of the upper flange and lower flange (2) of the H-beam (1) near the corner of the web to form a concave U-shaped groove (3). A1.2 Tunnel Bottom Treatment and Fiber Embedding After cutting, remove the slag from the bottom and edges of the tank, and then polish it to ensure that the tank walls are smooth. The distributed optical fiber is laid flat on the bottom of the laser-formed U-shaped groove (3); High-strength weather-resistant epoxy resin is injected into the tank, completely covering the distributed optical fibers and tightly bonding them to the tank wall.

9. The intelligent construction method for permanent retaining and modular partitioned steel bracing structure of deep foundation pits according to claim 7, characterized in that: The GNSS reference station is located on the ground at a distance of twice the depth of the pit; the support frame is at least 1.8m high.

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