A servo steel support axial force self-adaptive regulation and control system and method for a deep foundation pit

Abstract

The present application relates to the field of construction engineering construction technology, provide a kind of servo steel support axial force self-adapting regulation and control system and method for deep foundation pit, including mutually cooperative linkage's concrete-servo steel support hybrid support system, real-time monitoring subsystem, intelligent decision subsystem and servo execution subsystem;Hybrid support system is arranged in layers along depth and is arranged in zones and is arranged in echelon and is coupled rigidly by steel enclosing purlin;Real-time monitoring subsystem collects multidimensional environmental deformation data;Intelligent decision subsystem compares monitoring data with pre-play model based on, and calculates target axial force by adaptive pid algorithm and outputs instruction;Servo execution subsystem responds to instruction and drives servo oil cylinder to realize closed-loop regulation and control.The present application realizes the automatic accurate dynamic regulation and control of support axial force, effectively controls foundation pit deformation.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, and in particular relates to a servo steel support axial force adaptive control system and method for deep foundation pits. Background Technology

[0002] Currently, in deep foundation pit engineering support systems, while all-concrete support systems offer high stiffness and low deformation, they suffer from long construction cycles, difficult dismantling, and the inability to dynamically adjust axial force. All-steel support systems, while convenient to construct and reusable, have relatively low overall stiffness, and axial force is easily affected by temperature changes and soil creep, resulting in losses. Furthermore, traditional manual force supplementation methods suffer from low accuracy and slow response. While servo steel support technology, applied in recent years, can achieve real-time axial force adjustment, it mostly employs a manually preset fixed axial force control mode, failing to adaptively adjust according to real-time changes in foundation pit deformation. Moreover, it struggles to meet overall stiffness requirements independently in ultra-deep foundation pits. Therefore, existing technologies cannot balance the overall stiffness and dynamic adjustment flexibility of the support system, leading to insufficient deformation control accuracy and high safety risks in ultra-deep foundation pit projects in sensitive areas. Summary of the Invention

[0003] To address the problems of existing deep foundation pit support systems, which struggle to balance overall rigidity and dynamic adjustment flexibility, and the inability of existing servo systems to adaptively and precisely control based on real-time deformation, this application proposes a servo steel support axial force adaptive control system and method for deep foundation pits, thereby achieving automatic, precise, and dynamic control of support axial force and effective control of foundation pit deformation.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A servo steel support axial force adaptive control system for deep foundation pits, the system comprising a concrete-servo steel support hybrid support system, a real-time monitoring subsystem, an intelligent decision-making subsystem, and a servo execution subsystem that work together in a coordinated manner;

[0006] The concrete-servo steel support hybrid support system is arranged in a layered and zoned manner along the depth direction of the foundation pit, with a total of N supports. Among them, the first to M supports are concrete supports, and the M+1 to N supports are servo steel supports. The concrete supports and servo steel supports are rigidly coupled through steel walers to jointly construct a fully enclosed stress transmission platform.

[0007] The real-time monitoring subsystem includes a multi-source heterogeneous sensor group, including axial force sensors, diaphragm wall inclinometers, surface settlement monitoring points, groundwater level gauges, and deformation monitoring equipment for surrounding structures; the real-time monitoring subsystem is used to collect mechanical response and multi-dimensional environmental deformation data throughout the entire life cycle of foundation pit excavation around the clock;

[0008] The intelligent decision-making subsystem is configured with a finite element pre-analysis database, a data preprocessing module and an adaptive PID controller; the intelligent decision-making subsystem dynamically calculates the optimal target axial force of each supporting node through an adaptive PID algorithm based on the comparison and verification of multi-source real-time monitoring data and a pre-evaluation model, and outputs precise control instructions;

[0009] The servo execution subsystem includes a hydraulic pump station, a servo oil cylinder and a displacement sensor, which is communicatively connected to the intelligent decision-making subsystem; the servo execution subsystem responds to the control instruction and precisely drives the servo oil cylinder to extend and retract, thereby realizing high-precision closed-loop adaptive control of the axial force of the servo steel support.

[0010] Preferably, the spatial arrangement criteria of the concrete-servo steel support mixed support system include:

[0011] When the excavation depth H of the foundation pit is H≤15m, 1 concrete support and 2 to 3 servo steel supports are arranged;

[0012] When 15m<H≤25m, 2 concrete supports and 3 to 4 servo steel supports are arranged;

[0013] When H>25m, 3 concrete supports and 4 to 5 servo steel supports are arranged.

[0014] Preferably, for the foundation pit section adjacent to a sensitive area, the support spacing in the concrete-servo steel support mixed support system is directionally densified to 4 to 6m; the sensitive area includes an area adjacent to a subway or a pipeline.

[0015] Preferably, rigid coupling is realized between the concrete support and the steel waling through a high-strength connecting node of dissimilar materials;

[0016] The high-strength connecting node of dissimilar materials includes a pre-embedded steel plate and a connecting bolt, the end of the concrete support is implanted with the pre-embedded steel plate, and is tightly connected to the steel waling through the connecting bolt;

[0017] Shear studs are arranged inside the side of the concrete support close to the steel waling, and the shear studs are anchored and connected with the pre-embedded steel plate.

[0018] Preferably, the thickness of the pre-embedded steel plate is 20mm;

[0019] The diameter of the shear stud is 16mm, and the spacing between adjacent shear studs is 150mm;

[0020] The steel waling has an I-shaped steel section, stiffening rib plates are symmetrically welded on both sides of the web of the steel waling, and the thickness of the stiffening rib plate is 12mm;

[0021] The connecting bolt is an M24 high-strength connecting bolt;

[0022] The ends of the main concrete reinforcement bars inside the concrete support are welded to the embedded steel plate.

[0023] Preferably, the control triggering conditions for the adaptive PID controller to intervene in the solution in the intelligent decision-making subsystem include at least one of the following:

[0024] The horizontal displacement rate of the diaphragm wall is greater than 0.5 mm / d;

[0025] The surface subsidence rate is greater than 0.3 mm / d;

[0026] The sudden change in axial force fluctuation is greater than 10%.

[0027] The deformation of surrounding sensitive structures has reached 80% of the early warning management value.

[0028] Preferably, the servo steel support adopts a double H-beam cross section, and its ends are sealed with steel support end plates with a thickness of 30mm;

[0029] The axial force sensor is fitted between the steel support end plate and the hydraulic cylinder end plate;

[0030] The servo cylinder adopts a dual servo cylinder synchronous drive design and works with the displacement sensor to provide high-precision displacement feedback.

[0031] The present invention also provides a method for adaptive control of axial force of servo steel support in deep foundation pits, comprising the following steps:

[0032] A finite element pre-analysis database was obtained based on the three-dimensional finite element evolution model of deep foundation pits, and the initial design axial force and pre-applied axial force reference values ​​of each support were calibrated.

[0033] Concrete supports are poured in stages and servo steel supports are assembled. Real-time monitoring subsystems and servo execution subsystems are deployed simultaneously, and an initial preloaded axial force is applied to the supports using a graded loading strategy.

[0034] Collect multi-dimensional measured data of the foundation pit and its surrounding environment, and synchronize the multi-source data to the intelligent decision-making subsystem;

[0035] The intelligent decision-making subsystem integrates real-time monitoring data with the finite element pre-analysis database for deviation verification. When the control triggering conditions are met, the system calculates the target axial force value through the adaptive PID controller and sends a command to the servo execution subsystem to automatically adjust the axial force of the servo steel support.

[0036] The finite element pre-analysis database is dynamically and iteratively updated according to the actual deformation of the foundation pit, and alarms and emergency control responses are triggered when the monitoring data approaches or exceeds the warning threshold.

[0037] After the main structure of the basement is constructed to the specified elevation, the axial force of the servo steel support is released in stages and the support system is dismantled in sequence.

[0038] Preferably, the finite element pre-analysis database is dynamically and iteratively updated based on the actual deformation of the foundation pit, and an alarm and emergency control response are triggered when the monitoring data approaches or exceeds the warning threshold, including:

[0039] The design value of the support axial force for subsequent excavation conditions is optimized by using the measured data inversion mechanism, and the three-level safety early warning mechanism automatically triggers the audible and visual alarm and activates the emergency control response plan.

[0040] The axial force of the servo steel support is released in a tiered, flexible manner, and the support system is dismantled sequentially, including:

[0041] The force conversion mechanism of replacing the supports first and then removing them is strictly implemented. The axial force of the servo steel supports is released in stages and flexibly by the control system to smoothly complete the conversion of the main structural system.

[0042] This invention provides a servo-driven steel support axial force adaptive control system and method for deep foundation pits, which has the following beneficial effects:

[0043] This invention solves the contradiction between overall stability and dynamic flexibility that a single support system cannot achieve in terms of physical structure. It realizes a hybrid support mechanism that combines rigidity and flexibility, and optimizes the spatial stiffness field distribution. The upper concrete support and the lower servo steel support are arranged in layers and sections along the depth direction, and a fully enclosed stress transmission base is constructed by using steel walers to achieve rigid coupling. The high lateral stiffness of the concrete support is used to lock the macroscopic deformation benchmark of the foundation pit. At the same time, the dynamic adjustability of the lower servo steel support is used to achieve fine adjustment of the deep stress concentration area.

[0044] This invention integrates multi-source real-time monitoring data with a finite element pre-analysis database through an intelligent decision-making subsystem for comparison and verification, and uses an adaptive PID algorithm to dynamically calculate the optimal target axial force, replacing the traditional manual preset fixed value mode, and establishing a seamless closed-loop control mechanism of "perception-decision-execution-feedback". This mechanism can make autonomous decisions and respond with zero time delay based on soil creep and environmental changes, so that the real-time evolution of support stress and earth pressure is highly matched, significantly improving the timeliness and accuracy of axial force compensation.

[0045] This invention, through the synergistic effect of high-precision drive of the servo execution subsystem and multi-source data fusion algorithm, combined with lossless force transmission achieved by high-strength connection nodes of heterogeneous materials, ensures the physical execution accuracy of control commands, and can strictly control the deformation of the foundation pit within the sub-millimeter range. This meets the stringent deformation control requirements of the sensitive environment in the urban core area and effectively reduces the risk of secondary disasters caused by construction disturbance.

[0046] This invention achieves a technological leap from passive monitoring and recording to proactive risk intervention by introducing a measured data inversion mechanism to dynamically iterate and update the finite element pre-analysis database, and by incorporating multi-level safety early warning logic and emergency control schemes. Combined with a graded flexible unloading and a system conversion mechanism of replacing supports before removing supports, it eliminates the risk of stress mutation during structural conversion, builds a safety barrier throughout the entire construction life cycle, and reduces the amount of non-recyclable materials used, which is in line with the concept of green construction. Attached Figure Description

[0047] Figure 1 This is an overall structural block diagram of the servo steel support shaft force adaptive control system according to an embodiment of the present invention;

[0048] Figure 2 This is a planar stiffness distribution diagram of the concrete-servo steel support hybrid support system according to an embodiment of the present invention;

[0049] Figure 3 This is a longitudinal stress control cross-sectional view of the concrete-servo steel support hybrid support system according to an embodiment of the present invention;

[0050] Figure 4 This is a detailed diagram of the high-strength connection node between the concrete support and the steel waler, which are dissimilar materials, according to an embodiment of the present invention.

[0051] Figure 5 This is a detailed drawing of the dual-drive synchronous high-precision servo steel support end-effector execution module according to an embodiment of the present invention;

[0052] Figure 6 This is a flowchart of the decision subsystem based on digital pre-simulation and adaptive PID algorithm (intelligent decision subsystem flowchart) according to an embodiment of the present invention.

[0053] Figure 7 This is a flowchart of the active prevention and adaptive control process for deep foundation pits throughout their entire life cycle, according to an embodiment of the present invention.

[0054] In the diagram: 1-Concrete-servo steel support hybrid support system; 11-Concrete support; 12-Servo steel support; 13-Steel waler; 14-Lattice column; 15-Diaphragm wall; 2-Real-time monitoring subsystem; 21-Axial force sensor; 22-Diaphragm wall inclinometer; 23-Surface settlement monitoring point; 24-Groundwater level gauge; 25-Deformation monitoring equipment for surrounding structures; 3-Intelligent decision-making subsystem; 31-Finite element pre-analysis database; 32-Data preprocessing module; 33-Adaptive PID controller; 34-Safety early warning module; 4-Servo execution subsystem; 41-Hydraulic pump station; 42-Servo cylinder; 43-Displacement sensor; 51-Embedded steel plate; 52-Shear nail; 53-Stiffening rib plate; 54-Steel support end plate; 55-Cylinder end plate. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0056] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0057] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0058] Example 1

[0059] Reference Figure 1 This embodiment provides a servo-driven steel support axial force adaptive control system for deep foundation pits. The system comprises a concrete-servo-steel support hybrid support system 1, a real-time monitoring subsystem 2, an intelligent decision-making subsystem 3, and a servo execution subsystem 4, all working in tandem. These four subsystems together form a complete "perception-decision-execution-feedback" closed-loop control architecture. The concrete-servo-steel support hybrid support system 1 serves as the physical load-bearing entity, the real-time monitoring subsystem 2 acts as the sensory nerves, the intelligent decision-making subsystem 3 acts as the control brain, and the servo execution subsystem 4 acts as the execution muscles. Through bidirectional interaction of data flow and mechanical force, the four subsystems achieve dynamic and precise control over the support status of deep foundation pits.

[0060] Reference Figure 1 , Figure 2 , Figure 3 The concrete-servo steel bracing hybrid support system 1 is arranged in a layered and tiered manner along the depth of the foundation pit, with a total of N supports. The first to M supports are concrete supports 11, and the M+1 to N supports are servo steel supports 12. The concrete supports 11 and servo steel supports 12 are rigidly coupled through steel walers 13, collaboratively constructing a fully enclosed stress transmission platform. Specifically, this hybrid arrangement is not a simple material stacking, but a targeted design based on the distribution of soil pressure and deformation control requirements during deep foundation pit excavation. The upper concrete supports 11, with their high lateral stiffness, provide a stable macroscopic deformation benchmark for the entire support system, effectively locking in the overall stability of the shallow and middle layers of the foundation pit; the lower servo steel supports 12, with their dynamically adjustable characteristics, undertake the task of fine-tuning the deep stress concentration zone. The rigid coupling between the two through the steel waler 13 ensures that the support components of different materials and functions can form a continuous and uninterrupted stress-bearing whole, so that the water and soil pressure can be evenly transmitted and redistributed in the fully enclosed stress transmission base, avoiding the stress concentration or force transmission failure caused by weak connection in traditional hybrid support, thus laying the foundation for rigidity and flexibility and collaborative work at the physical structure level.

[0061] Reference Figure 1 The real-time monitoring subsystem 2 comprises a multi-source heterogeneous sensor group, including an axial force sensor 21, a diaphragm wall inclinometer 22, a surface settlement monitoring point 23, a groundwater level gauge 24, and deformation monitoring equipment for surrounding structures 25. This subsystem is used to collect mechanical response and multi-dimensional environmental deformation data throughout the entire excavation cycle of the foundation pit, operating around the clock. Specifically, this subsystem overcomes the limitations of single-dimensional monitoring, constructing a three-dimensional perception network covering the foundation pit itself and its surrounding environment. The axial force sensor 21 directly acquires the stress state of the support system, the diaphragm wall inclinometer 22 reflects the deep deformation of the retaining structure, the surface settlement monitoring point 23 monitors the ground response caused by soil loss, the groundwater level gauge 24 captures the impact of hydrological conditions on soil strength, and the deformation monitoring equipment for surrounding structures 25 is directly related to the safety status of environmental protection targets. These multi-source heterogeneous data are synchronized in time and complementary in space, providing comprehensive and accurate on-site status input for intelligent decision-making, and are an indispensable data foundation for achieving adaptive control. It should be understood that although this embodiment lists five types of typical sensors, in other embodiments, other types of sensing devices can be added or replaced according to actual engineering needs, as long as they can meet the multi-dimensional sensing function of foundation pit mechanical response and environmental deformation.

[0062] Reference Figure 1The intelligent decision-making subsystem 3 is equipped with a finite element pre-analysis database 31, a data preprocessing module 32, and an adaptive PID controller 33. Based on the comparison and verification between multi-source real-time monitoring data and the pre-simulation model, the intelligent decision-making subsystem 3 dynamically calculates the optimal target axial force for each support node using an adaptive PID algorithm and outputs precise control commands. Specifically, this subsystem realizes a shift from experience-driven to data- and model-driven approaches. The finite element pre-analysis database 31 stores the theoretical responses of various working conditions pre-simulated based on geological survey and design parameters, representing the evolution law of the foundation pit under ideal conditions. The data preprocessing module 32 filters, denoises, and removes outliers from the real-time monitoring data to ensure the reliability of the input data. The adaptive PID controller 33 compares the processed measured data with the pre-simulation model in real time. When a deviation occurs, it does not simply trigger a fixed threshold alarm, but dynamically calculates the optimal target axial force required to eliminate the deviation using an adaptive algorithm. This mechanism enables the system to autonomously adjust its control strategy based on nonlinear factors such as soil creep and construction disturbance, continuously approaching the optimal support state without human intervention, significantly improving the timeliness and accuracy of control.

[0063] Reference Figure 1 The servo execution subsystem 4 includes a hydraulic pump station 41, a servo cylinder 42, and a displacement sensor 43, which are communicatively connected to the intelligent decision-making subsystem 3. The servo execution subsystem 4 responds to control commands and precisely drives the servo cylinder 42 to extend and retract, thereby achieving high-precision closed-loop adaptive control of the axial force of the servo steel support 12. Specifically, this subsystem is the key execution terminal that transforms digital world decisions into physical world forces. The hydraulic pump station 41 provides a stable and controllable power source. The servo cylinder 42, as the core actuating component, has its extension and retraction stroke and output force controlled by commands issued by the intelligent decision-making subsystem 3. The displacement sensor 43 provides real-time feedback on the actual position of the cylinder, forming a local closed loop at the execution level, ensuring a high degree of consistency between mechanical actions and digital commands. Through this high-precision execution mechanism, the system can accurately apply the target axial force calculated by the adaptive PID controller to the servo steel support 12 and promptly compensate for axial force losses caused by factors such as temperature changes and loose joints. Ultimately, it achieves millisecond-level response and kilonewton-level precision in maintaining the foundation pit support status, completing the final link of the entire adaptive control closed loop.

[0064] Example 2

[0065] Reference Figure 2 , Figure 3, the spatial arrangement criteria of the concrete-servo steel support mixed support system 1 include: when the excavation depth H of the foundation pit is ≤15m, 1 concrete support 11 and 2~3 servo steel supports 12 are arranged; when 15m<H≤25m, 2 concrete supports 11 and 3~4 servo steel supports 12 are arranged; when H>25m, 3 concrete supports 11 and 4~5 servo steel supports 12 are arranged. This spatial arrangement criterion is not a simple list of empirical values, but a mechanical model established based on the distribution law of earth pressure of deep foundation pits and the matching principle of support structure stiffness.

[0066] In this embodiment, taking a foundation pit with an excavation depth of 22m as an example, an arrangement scheme of 2 concrete supports + 3 servo steel supports is adopted, the underground continuous wall 15 is used as the foundation pit enclosure structure, and the lattice column 14 is used as the vertical load-bearing member of the support system, for supporting the bottoms of the concrete supports 11 and / or the servo steel supports 12.

[0067] Further, for the foundation pit section adjacent to the sensitive area, the support spacing in the concrete-servo steel support mixed support system 1 is directionally encrypted to 4~6m; the sensitive area includes an area adjacent to a subway or a pipeline. The "directional encryption" strategy here embodies the dynamic response mechanism of the present invention to environmental sensitivity, which is different from the rigid mode of uniform spacing for the entire foundation pit in traditional design. By encrypting the support spacing to 4~6m, the local planar stiffness and vertical constraint density can be significantly improved, so that the support system forms a "stiffness reinforcement zone" in the sensitive area.

[0068] Embodiment 3

[0069] Reference Figure 4 , in this embodiment, rigid coupling between the concrete support 11 and the steel waling 13 is realized through a high-strength connection node of dissimilar materials.

[0070] This high-strength connection node for heterogeneous materials includes an embedded steel plate 51 and connecting bolts. The embedded steel plate 51 is inserted into the end of the concrete support 11 and is fastened to the steel waler 13 by the connecting bolts. Simultaneously, shear studs 52 are provided inside the concrete support 11 near the steel waler 13, and the shear studs 52 are anchored to the embedded steel plate 51. The core purpose of this structural design is to solve the interface coordination problem between concrete and steel, two materials with vastly different elastic moduli and Poisson's ratios, when subjected to the same force. In this embodiment, the embedded steel plate 51 acts as a rigid transition medium, transforming the concentrated axial force transmitted from the steel waler 13 into a uniformly distributed surface load acting on the concrete end face. The shear studs 52 penetrate deep into the concrete to form mechanical interlocking keys, effectively resisting interfacial shear forces and preventing tensile cracking. The connecting bolts provide strong axial preload, generating sufficient friction between the contact surfaces to assist in force transmission. The three components work together to construct a composite force transmission system that integrates pressure bearing, shear resistance, and friction, truly realizing non-destructive force transmission and rigid coupling between heterogeneous materials, and ensuring the mechanical continuity of the hybrid support system in the fully enclosed stress transmission base.

[0071] To further quantify the load-bearing capacity of the nodes and ensure reliability, this embodiment refines the key structural parameters of the nodes. Specifically, the thickness of the embedded steel plate 51 is set to 20mm; the diameter of the shear studs 52 is 16mm, and the spacing between adjacent shear studs 52 is 150mm; the steel waler 13 uses an I-beam cross-section, with stiffening ribs 53 symmetrically welded to both sides of its web, and the thickness of the stiffening ribs 53 is 12mm; M24 high-strength connecting bolts are used; and the ends of the main concrete reinforcement bars inside the concrete support 11 are welded to the embedded steel plate 51.

[0072] Example 4

[0073] In this embodiment, the control trigger conditions for the adaptive PID controller 33 in the intelligent decision-making subsystem 3 to intervene in the calculation include at least one of the following: the horizontal displacement rate of the diaphragm wall is greater than 0.5 mm / d; the surface settlement rate is greater than 0.3 mm / d; the sudden change in the axial force fluctuation of the support is greater than 10%; and the deformation of the surrounding sensitive structures reaches 80% of the early warning management value.

[0074] Example 5

[0075] Reference Figure 5In this embodiment, the servo steel support 12 adopts a double-section H-beam steel cross-section, with a 30mm thick steel support end plate 54 welded to its end to prevent local buckling; the axial force sensor 21 is embedded between the steel support end plate 54 and the cylinder end plate 55 to achieve zero-delay force sensing; the servo cylinder 42 adopts a dual servo cylinder synchronous drive design and works with the displacement sensor 43 for high-precision displacement feedback. It is this high-precision hardware execution architecture that, together with the adaptive PID algorithm and database inversion mechanism, forms a perfect hardware-software synergy, achieving an axial force control accuracy of ±5kN, a displacement control accuracy of ±0.1mm, and a system end-to-end response delay of no more than 30 seconds, completely solving the problem of low accuracy in traditional manual force supplementation.

[0076] Example 6

[0077] Reference Figure 7 , Figure 6 This embodiment provides a method for adaptive control of axial force of deep foundation pit servo steel support based on the aforementioned system. This method covers the entire life cycle of proactive prevention and control from construction preparation to support removal, and specifically includes the following steps:

[0078] Step S100 involves acquiring the finite element pre-analysis database 31 based on the three-dimensional finite element evolution model of the deep foundation pit, and calibrating the initial design axial force and pre-applied axial force benchmark values ​​for each support. Specifically, this step does not involve tedious on-site numerical modeling, but rather directly calls or imports pre-built digital twin results as control benchmarks. At the execution level, the intelligent decision-making subsystem 3 reads the finite element pre-analysis database 31, which contains engineering geological survey data, retaining structure design parameters, and excavation condition sequences. Through the built-in benchmark value generation module, it automatically parses the theoretical stress envelopes for each concrete support 11 and servo steel support 12 at different excavation stages. Based on this, the system, combining safety factors and deformation control standards, accurately calibrates the initial design axial force and pre-applied axial force benchmark values ​​for each support. These benchmark values ​​constitute the "theoretical scale" for all subsequent adaptive controls, giving the system a clear target orientation from the beginning of construction. This avoids the problem of excessive or insufficient pre-applied force due to experience-based estimations in traditional construction, laying a digital foundation for precise control throughout the entire lifecycle.

[0079] In step S200, the concrete supports 11 are poured in stages and the servo steel supports 12 are assembled. Simultaneously, the real-time monitoring subsystem 2 and the servo execution subsystem 4 are deployed, and an initial pre-loaded axial force is applied to the supports using a graded loading strategy. Specifically, this step achieves the first alignment of the physical entity with the digital reference. During construction, the principle of "layered excavation, supporting before excavation" is strictly followed. Following the spatial arrangement criteria described in Example 2, the pouring and curing of the concrete supports 11 and the assembly and connection of the servo steel supports 12 are completed in stages from top to bottom. At the same time, sensing devices such as the axial force sensor 21 and the diaphragm wall inclinometer 22, as well as execution devices such as the hydraulic pump station 41 and the servo cylinder 42, are installed in place, and the communication link is tested and integrated. When applying the initial preloaded axial force, the crude approach of loading in one go was abandoned. Instead, a graded loading strategy was adopted, for example, applying pressure in three stages: 30%, 50%, and 70% of the design value. After each stage of loading, the load was held for a period of time to stabilize. Only after the deformation data fed back by the real-time monitoring subsystem 2 converged and showed no anomalies could the next stage of loading be applied. This steady-state approximation loading method effectively eliminated the influence of component assembly gaps and inelastic deformation of nodes on axial force transmission, ensuring that the support system was in a healthy and reliable stress state before formal control was implemented.

[0080] Step S300 involves collecting multi-dimensional measured data of the foundation pit and its surrounding environment, and synchronizing this multi-source data to the intelligent decision-making subsystem 3. Specifically, this is a crucial step in maintaining the continuous flow of closed-loop control information. The real-time monitoring subsystem 2 continuously acquires multi-dimensional state parameters such as axial force, deep horizontal displacement, surface settlement, groundwater level, and deformation of surrounding structures according to a preset high-frequency sampling period. The collected raw data undergoes preliminary filtering, noise reduction, and outlier removal at edge computing nodes, and is then synchronized to the data preprocessing module 32 of the intelligent decision-making subsystem 3 via 5G or a dedicated fiber optic network within milliseconds. It should be understood that this data synchronization involves not only timestamp alignment but also spatial topology mapping. The system automatically associates discrete sensor readings with corresponding nodes in the finite element model, forming a real-time state mirror isomorphic to the digital twin, thus providing a high-fidelity input source for subsequent deviation verification.

[0081] In step S400, the intelligent decision-making subsystem 3 integrates real-time measured data with the finite element pre-analysis database 31 to verify the deviation. When the control triggering conditions are met, the adaptive PID controller 33 calculates the target axial force value and sends a command to the servo execution subsystem 4 to automatically adjust the axial force of the servo steel support 12. Specifically, this step is the execution center for realizing the core value of "adaptive" in this invention. The intelligent decision-making subsystem 3 compares the real-time state image obtained in step S300 with the theoretical prediction value in the finite element pre-analysis database 31 point by point to calculate the deviation amount and the deviation change rate. Once the deviation state reaches any one of the four triggering conditions described in Example 4 (such as the horizontal displacement rate of the diaphragm wall being greater than 0.5 mm / d), the adaptive PID controller 33 is immediately activated. The controller no longer relies on manually set fixed compensation amounts, but rather, based on the current deviation characteristics and the system's historical response characteristics, uses an adaptive algorithm to tune the PID parameters online and dynamically calculate the optimal target axial force value required to eliminate the deviation. Subsequently, precise control commands are sent to the servo execution subsystem 4, driving the servo cylinder 42 to complete the axial force adjustment with an accuracy of ±5kN and a response delay of no more than 30s. The entire process requires no manual intervention, truly achieving a seamless closed loop from "perceiving abnormalities" to "executing corrections," ensuring that the support stress always closely follows the real-time evolution of earth pressure.

[0082] Step S500 involves dynamically updating the finite element pre-analysis database 31 based on the actual deformation of the foundation pit, and triggering alarms and emergency control responses when the monitored data approaches or exceeds the warning threshold. Specifically, this step endows the system with the dual capabilities of continuous learning and proactive defense. On the one hand, after each control measure meets the standard and the system enters a steady state, the intelligent decision-making subsystem 3 automatically extracts the measured response data for that period and uses an inversion algorithm to correct the geotechnical parameters or boundary conditions in the finite element pre-analysis database 31, so that the pre-model continuously "evolves" as the project progresses, becoming closer and closer to the actual site conditions, thereby improving the accuracy of subsequent working condition prediction and control. On the other hand, the safety early warning module 34 monitors the safety margin of various indicators in real time. When the monitored data approaches or exceeds the preset three-level warning threshold, the system will not only immediately trigger an audible and visual alarm to notify on-site personnel, but also automatically activate the corresponding emergency control response plan according to the warning level, such as forcibly increasing the axial force limit of the servo steel support 12, increasing the monitoring frequency, or implementing measures such as linkage grouting reinforcement. This combination of "model iteration + proactive early warning" elevates risk management from passive post-event recording to proactive pre-event intervention and in-event control.

[0083] Step S600: After the basement main structure is constructed to the specified elevation, the axial force of the servo steel support 12 is released in stages with flexibility, and the support system is dismantled sequentially. Specifically, this is a crucial step to ensure a safe and smooth transition during the final stage of the project. After the main structure reaches its design strength and has self-bearing capacity, the servo execution subsystem 4 does not release the axial force instantly, but strictly executes a staged flexible unloading procedure. For example, the system releases the axial force in stages of 10% to 20%, with a load observation period set after each stage of unloading. Only after the real-time monitoring subsystem 2 confirms that the deformation of the enclosure structure and the main structure is coordinated and there are no abnormal sudden changes can the next stage of unloading be carried out, until the axial force is completely reduced to zero. This controlled and gradual unloading method effectively avoids the risk of stress redistribution impact and structural damage caused by the sudden disappearance of support force, ensuring absolute safety during the force transfer process from the "temporary support system" to the "permanent main structure". Only after the axial force has been fully released and safety has been confirmed can the physical dismantling and recycling of the servo steel support 12 and steel waler 13 be carried out, achieving a perfect unity of green construction and safety management.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A servo-driven steel support axial force adaptive control system for deep foundation pits, characterized in that, The system comprises a concrete-servo steel support mixed support system (1), a real-time monitoring subsystem (2), an intelligent decision-making subsystem (3), and a servo execution subsystem (4) that cooperate and interact with each other; The concrete-servo steel support mixed support system (1) is arranged in a layered, zoned and stepped manner along the depth direction of the foundation pit, with a total of N supports, of which the 1st to Mth supports are concrete supports (11), and the (M+1)th to Nth supports are servo steel supports (12); the concrete supports (11) and the servo steel supports (12) are rigidly coupled through steel waling (13), to collaboratively form a fully enclosed stress transmission base; The real-time monitoring subsystem (2) includes a multi-source heterogeneous sensor group, including axial force sensors (21), diaphragm wall inclinometers (22), surface settlement monitoring points (23), groundwater level gauges (24) and surrounding structure deformation monitoring equipment (25); the real-time monitoring subsystem (2) is used to collect mechanical response and multi-dimensional environmental deformation data throughout the full cycle of foundation pit excavation around the clock; The intelligent decision-making subsystem (3) is equipped with a finite element pre-analysis database (31), a data preprocessing module (32) and an adaptive PID controller (33); the intelligent decision-making subsystem (3) dynamically calculates the optimal target axial force of each support node through the adaptive PID algorithm based on the comparison and verification of multi-source real-time monitoring data and the pre-validation model, and outputs precise regulation instructions; The servo execution subsystem (4) includes a hydraulic pump station (41), a servo cylinder (42) and a displacement sensor (43), which is communicatively connected to the intelligent decision-making subsystem (3); the servo execution subsystem (4) responds to the regulation instruction and precisely drives the servo cylinder (42) to extend and retract, so as to realize high-precision closed-loop adaptive regulation of the axial force of the servo steel support (12).

2. The servo-driven steel support axial force adaptive control system for deep foundation pits according to claim 1, characterized in that, The spatial arrangement criteria of the concrete-servo steel support mixed support system (1) include: When the excavation depth H of the foundation pit is ≤ 15m, 1 concrete support (11) and 2 to 3 servo steel supports (12) are provided; When 15m < H ≤ 25m, 2 concrete supports (11) and 3 to 4 servo steel supports (12) are provided; When H > 25m, 3 concrete supports (11) and 4 to 5 servo steel supports (12) are provided.

3. The servo-driven steel support axial force adaptive control system for deep foundation pits according to claim 2, characterized in that, For the foundation pit section adjacent to the sensitive area, the support spacing in the concrete-servo steel support mixed support system (1) is targetedly encrypted to 4~6m; the sensitive area includes the area adjacent to subways or pipelines.

4. The servo-driven steel support axial force adaptive control system for deep foundation pits according to claim 1, characterized in that, Rigid coupling is realized between the concrete support (11) and the steel waling (13) through high-strength connection nodes of dissimilar materials; The high-strength connection node of dissimilar materials includes a pre-embedded steel plate (51) and connecting bolts, the end of the concrete support (11) is embedded with the pre-embedded steel plate (51), and is tightly connected to the steel waling (13) through the connecting bolts; Shear studs (52) are arranged inside the concrete support (11) on the side close to the steel waling (13), and the shear studs (52) are anchored and connected to the pre-embedded steel plate (51).

5. The servo-driven steel support axial force adaptive control system for deep foundation pits according to claim 4, characterized in that, The thickness of the pre-embedded steel plate (51) is 20mm; The diameter of the shear stud (52) is 16mm, and the spacing between adjacent shear studs (52) is 150mm; The steel waler (13) has an I-beam cross section, and stiffening ribs (53) are symmetrically welded on both sides of its web. The thickness of the stiffening ribs (53) is 12mm. The connecting bolts are M24 high-strength connecting bolts; The ends of the main concrete reinforcement bars inside the concrete support (11) are welded to the embedded steel plate (51).

6. The servo-driven steel support axial force adaptive control system for deep foundation pits according to claim 1, characterized in that, The control triggering conditions for the intervention of the adaptive PID controller (33) in the intelligent decision-making subsystem (3) include at least one of the following: The horizontal displacement rate of the diaphragm wall is greater than 0.5 mm / d; The surface subsidence rate is greater than 0.3 mm / d; The sudden change in axial force fluctuation is greater than 10%. The deformation of surrounding sensitive structures has reached 80% of the early warning management value.

7. The servo-driven steel support axial force adaptive control system for deep foundation pits according to claim 1, characterized in that, The servo steel support (12) adopts a double H-shaped steel section, and its ends are sealed with steel support end plates (54) with a thickness of 30mm. The axial force sensor (21) is fitted between the steel support end plate (54) and the cylinder end plate (55); The servo cylinder (42) adopts a dual servo cylinder synchronous drive design and works with the displacement sensor (43) to provide high-precision displacement feedback.

8. A method for adaptive control of axial force of servo steel support in deep foundation pits based on the system described in claim 1, characterized in that, It includes the following steps: The finite element pre-analysis database was obtained based on the three-dimensional finite element evolution model of the deep foundation pit (31), and the initial design axial force and pre-applied axial force reference values ​​of each support were calibrated. Concrete supports (11) are poured in stages and servo steel supports (12) are assembled. Real-time monitoring subsystem (2) and servo execution subsystem (4) are deployed simultaneously, and an initial preloaded axial force is applied to the supports using a graded loading strategy. Collect multi-dimensional measured data of the foundation pit body and surrounding environment, and synchronize the multi-source data to the intelligent decision-making subsystem (3). The intelligent decision-making subsystem (3) integrates real-time monitoring data with the finite element pre-analysis database (31) to perform deviation verification. When the control triggering conditions are met, the adaptive PID controller (33) calculates the target axial force value and sends an instruction to the servo execution subsystem (4) to automatically adjust the axial force of the servo steel support (12). The finite element pre-analysis database (31) is dynamically updated iteratively according to the actual deformation of the foundation pit, and an alarm and emergency control response are triggered when the monitoring data approaches or exceeds the warning threshold. After the main structure of the basement is constructed to the specified elevation, the axial force of the servo steel support (12) is released in stages and the support system is dismantled in sequence.

9. The method for adaptive control of axial force of servo steel support in deep foundation pits according to claim 8, characterized in that, The finite element pre-analysis database (31) is dynamically and iteratively updated based on the actual deformation of the foundation pit, and alarms and emergency control responses are triggered when the monitoring data approaches or exceeds the warning threshold, including: The design value of the support axial force for subsequent excavation conditions is optimized by using the measured data inversion mechanism, and the three-level safety early warning mechanism automatically triggers the audible and visual alarm and activates the emergency control response plan. The axial force of the graded flexible release servo steel support (12) and the sequential dismantling of the support system include: Strictly implement the force conversion mechanism of replacing the support first and then removing the support, and use the control system to flexibly release the axial force of the servo steel support (12) in stages to smoothly complete the conversion of the main structure system.

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