Water-rich karst area subway station deep foundation pit enclosure structure anti-seepage control system and method

Abstract

The application relates to the technical field of civil engineering construction, and discloses a water-rich karst area subway station deep foundation pit enclosure structure anti-seepage control system and method, which comprises a vein module embedded in the enclosure structure, a medium supply module on the ground and a sensing and control module. The vein module is integrated with an integrated distributed optical fiber and comprises two core channels. One is a predictive pressure relief microchannel connected with an electrically controlled micro valve, which can actively release locally excessive water and soil pressure before the structure is damaged according to strain monitoring data. The other is a repair micro vein provided with a pressure-sensitive soluble seal head at the tail end. When the external water pressure increases sharply due to leakage, the seal head is broken, and the internal responsive repair medium is released to perform in-situ self-healing repair. Through strain and temperature cooperative monitoring, the application realizes the transformation from "passive repair" to "active prediction and immediate self-healing", and significantly improves the safety, durability and whole life cycle maintenance efficiency of the underground engineering enclosure structure.

Description

Technical Field

[0001] This invention relates to the field of civil engineering construction technology, and in particular to a seepage prevention control system and method for deep foundation pit retaining structures of subway stations in water-rich karst areas. Background Technology

[0002] Deep foundation pit engineering is a crucial aspect of urban underground space development, and the safety and stability of its retaining structure are paramount under complex water and soil pressures. Currently, to ensure the safety of the retaining structure, the engineering community typically employs a combination of structural health monitoring and leakage repair (such as post-grouting). However, existing technologies have inherent limitations in dealing with the rapidly changing underground environment.

[0003] In current practices, monitoring systems and remedial measures are two separate processes with significant response delays between them. Monitoring systems, whether traditional point sensors or more advanced distributed fiber optic sensors, primarily function to detect problems, such as identifying abnormal strain or temperature anomalies caused by leaks. However, the entire process from problem detection to resolution exhibits a significant lag. Even if monitoring data indicates a risk, it still requires manual assessment by engineers, followed by the deployment of personnel and equipment to the site for remedial work such as drilling and grouting. This process is not only time-consuming and may miss the optimal window for addressing the problem, leading to the expansion of localized damage, but also incurs high maintenance costs and potential construction safety risks due to extensive manual intervention.

[0004] More importantly, this "monitoring-alarm-remediation" model is essentially a passive response mechanism. It focuses on repairing damage that has already occurred (such as structural cracking and water leakage), but lacks the ability to proactively intervene before structural failure occurs. Existing technologies cannot effectively predict and mitigate the root causes of damage, such as excessively high hydrostatic pressure that gradually accumulates in localized areas when the structure is intact, potentially inducing cracking. Although there are precedents such as pre-embedded grouting pipes, the activation of these pipeline systems still relies on manual judgment and operation, failing to form a closed loop with real-time structural health data to achieve intelligent and automatic responses. Therefore, the existing technological system cannot achieve the leap from "passive repair" to "proactive prevention," and is insufficient to meet the demands of modern major projects for higher levels of safety, durability, and intelligent operation and maintenance throughout their entire lifecycle. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a seepage prevention control system and method for deep foundation pit retaining structures in subway stations in water-rich karst areas. The aim is to solve the technical problems that existing seepage prevention measures for deep foundation pit retaining structures in water-rich karst areas mainly rely on passive sealing, lack the ability to actively predict and intervene in structural stress states, and have untimely repair responses and low automation after leakage occurs.

[0006] To address the aforementioned technical problems, the first aspect of this invention provides a seepage prevention control system for the retaining structure of deep foundation pits in subway stations located in water-rich karst areas. This system, through dual-modal monitoring of strain and temperature, combined with active stress relief and passive repair functions, achieves predictive control of leakage risks in the retaining structure and self-healing sealing after leakage occurs, thereby improving the long-term safety and stability of the retaining structure.

[0007] The system includes: The network module is embedded within the enclosure structure. The network module includes: a main network for circulating and delivering responsive repair media, and predictive pressure-relieving microchannels for actively releasing local water pressure; the network module is also used to perform leakage repair. A media supply module for containing and supplying the responsive remediation medium, which triggers solidification upon contact with groundwater; The sensing and control module, connected to the network module and the medium supply module, is used to monitor the strain and temperature of the enclosure structure, and control the network module to perform functions such as actively releasing local water pressure or repairing leaks based on the monitoring results.

[0008] In one specific embodiment, the sensing and control module includes: A distributed sensing subunit includes an integrated distributed optical fiber arranged along the entire main network, used to acquire strain field data of the enclosure structure and temperature field data inside the main network in real time. The intelligent control subunit, connected to the distributed sensing subunit, is used to process the strain field data to determine whether the predictive pressure relief microchannel needs to be opened, and to process the temperature field data to determine whether leakage has occurred.

[0009] Preferably, the intelligent control subunit processes the strain field data using a preset predictive stress relief mode algorithm. The activation condition of the predictive stress relief mode algorithm is: at a certain location of the enclosure structure... At this point, the actual strain value Greater than the critical strain threshold at this location And its strain growth rate Greater than the preset strain growth rate threshold When the activation condition is met, the intelligent control subunit is activated at that position. The predictive stress-relieving microchannel at the location.

[0010] In one specific embodiment, the activation condition of the stress-relieving mode prediction algorithm can be achieved through the following logical function. Make a judgment: ; in: This is the activation state function for the pressure relief valve. A value of 1 indicates that the activation condition is met, and a value of 0 indicates that the activation condition is not met. This refers to the positional variable along the enclosure structure; It is a time variable; For distributed sensing subunits at time ,Location The real-time strain value measured at the location; Preset according to structural design parameters, and position The relevant critical strain threshold; This is the partial derivative of the real-time strain value with respect to time, i.e., the strain rate of increase; The preset strain growth rate threshold; For logical AND operator.

[0011] More preferably, the intelligent control subunit processes the temperature field data using a preset self-healing repair mode algorithm. The activation condition of the self-healing repair mode algorithm is: at a certain position of the main network... At that location, its background reference temperature With real-time temperature value The difference is greater than the preset temperature difference trigger threshold. Wherein, the background reference temperature The previous preset time window for the current moment The historical moving average temperature within the region.

[0012] In one specific embodiment, the network module further includes a repair micro-network connected to the main network. The end of the repair micro-network is provided with a pressure-sensitive soluble cap, which breaks when the pressure difference between the external groundwater seepage pressure and the internal pressure of the main network exceeds its rupture threshold, thereby causing the responsive repair medium to flow out.

[0013] In one specific embodiment, an electrically controlled micro-solenoid valve is installed at the end of the predictive stress-relieving microchannel. The electrically controlled micro-solenoid valve is electrically connected to the sensing and control module and is controlled by the module to open or close.

[0014] In one specific embodiment, the responsive remediation medium provided by the medium supply module has the following performance characteristics: it circulates stably in a low-viscosity liquid state within the vascular module; it contains a physically isolated activator-coagulant; and when the responsive remediation medium comes into contact with groundwater, the physically isolated activator-coagulant is released, thereby undergoing an in-situ polymerization reaction to form a solidified product.

[0015] Preferably, the location of the predictive stress-relieving microchannel is predetermined based on the stress concentration area determined by the finite element analysis of the soil-rock interaction during the foundation pit excavation process.

[0016] A second aspect of this invention provides a method for seepage control using any of the aforementioned seepage control systems. This method achieves full-cycle seepage control of the retaining structure by actively predicting and releasing local water pressure, and automatically sealing leaks after they occur.

[0017] The method includes the following steps: Predictive stress relief steps: The strain field of the enclosure structure is continuously monitored through the sensing and control module; when the strain value and strain rate increase at a certain location are detected to exceed a preset threshold at the same time, the local water pressure is actively released through the network module. Self-healing repair steps: The temperature field within the network module is continuously monitored by the sensing and control module; when the temperature drop at a certain location exceeds a preset threshold, it is determined that a leak has occurred at that location, and the responsive repair medium flows out through the network module, automatically solidifies upon contact with groundwater at the leak point, thereby sealing the leak channel.

[0018] The present invention has the following beneficial effects: This invention continuously monitors the real-time strain value and strain rate of the building envelope through its sensing and control module, and makes judgments based on a predictive stress relief mode algorithm. When the structural stress exceeds a preset threshold and shows a rapid increasing trend, the system can automatically open predictive stress relief microchannels at specific locations to release local water pressure. This design transforms traditional passive post-disaster repair into proactive pre-disaster prevention, eliminating risks before structural damage and leakage occur, and significantly improving the safety of the building envelope.

[0019] This invention utilizes distributed optical fibers deployed along the main network to precisely sense the temperature field. Once external groundwater intrusion causes a local temperature drop and triggers a threshold, the system determines that a leak has occurred. At this point, the responsive repair medium in the network module automatically flows to the leak point, rapidly solidifying in situ upon contact with water to seal the channel. This process requires no manual intervention, offers rapid response, and precise location, significantly shortening fault repair time and reducing maintenance costs and secondary risks caused by leak expansion.

[0020] This invention integrates the distributed sensing optical fibers with the main network for delivering the repair medium in a physical structure. This design ensures a high degree of spatial consistency between the sensing monitoring points and the repair execution points, enabling precise positioning and targeted repair for both strain-based pressure relief and temperature-based leak sealing. This integrated structure simplifies system complexity, improves overall operational reliability and control accuracy, and avoids potential positioning errors in the monitoring and execution stages of traditional separate systems. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall system structure of the present invention; Figure 2 This is a partial structural diagram of the network module of the present invention; Figure 3 This is a flowchart of the predictive stress relief mode control logic of the present invention; Figure 4 This is a flowchart of the self-healing repair mode monitoring logic of the present invention; Figure 5 This is a schematic diagram illustrating the working principle of the pressure-sensitive soluble end cap of the present invention; Figure 6 This is a schematic diagram illustrating the activation principle of the responsive repair medium of the present invention.

[0022] Among them, 10. Vein module; 11. Main vein; 12. Predictive pressure relief microchannel; 121. Electrically controlled micro solenoid valve; 13. Repair microvein; 131. Pressure-sensitive soluble end cap; 20. Medium supply module; 21. Liquid storage tank; 22. Micro-power circulating pump; 23. Pressure sensor; 30. Sensing and control module. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0024] See attached document Figure 1 , Figure 1 This is a schematic diagram of a seepage prevention control system according to an embodiment of the present invention. The present invention provides a seepage prevention control system for the retaining structure of a deep foundation pit of a subway station in a water-rich karst area. The system includes: a network module 10, a medium supply module 20, and a sensing and control module 30.

[0025] The network module 10 is embedded inside the enclosure structure (not shown in the figure). The network module 10 is used to construct the circulation path of the responsive repair medium and serves as a functional carrier for performing leakage repair and actively releasing local water pressure.

[0026] The media supply module 20 is fluidly connected to the input and output terminals of the network module 10. It is used to store and supply responsive repair media to the network module 10, while receiving media returned from the network module 10, forming a complete loop.

[0027] The sensing and control module 30 establishes signal connections with the network module 10 and the medium supply module 20, respectively. The sensing and control module 30 is used to acquire monitoring data from the sensing elements inside the network module 10, process the data and make decisions according to a preset logic algorithm, and finally generate and send control commands to the actuators of the network module 10 and the drive elements of the medium supply module 20.

[0028] In the specific implementation process, the network module 10 is pre-installed during the construction phase of the retaining structure. Specifically, after the steel cage of the retaining structure (such as a single section of a diaphragm wall or a bored pile) is manufactured and before it is lowered and hoisted, the pipeline network of the network module 10 is laid according to the position determined by the design drawings, and it is fixed to the inner or outer surface of the steel cage using cable ties or special clips.

[0029] The location and density of the pipeline network in the network module 10 are predetermined based on the geological survey report and the results of the finite element analysis of the soil-rock interaction before the excavation of the foundation pit. For example, the density of the functional channels in the network module 10 is increased in areas of stress concentration predicted by the structural design (such as the external corner of the foundation pit, the area around the opening), areas with strong karst development, or at the joints between new and old concrete structures.

[0030] After the reinforcement cage is lowered into the trench section and the subsequent concrete pouring is completed, the network module 10 forms an integrated embedded functional system with the retaining structure. Its input and output ports for external connection are reserved and led out to the top surface of the retaining structure to establish fluid and electrical communication with the media supply module 20 and sensing and control module 30 installed on the ground during the excavation and subsequent use phases.

[0031] See attached document Figure 1 and attached Figure 2 , attached Figure 2 This is a partial structural schematic diagram of the network module 10 according to an embodiment of the present invention.

[0032] The network module 10 is a functional network embedded in the enclosure structure, which includes a main network 11, a predictive stress-relieving microchannel 12, and a repair micronetwork 13.

[0033] The main conduit 11 is the basic pathway for the entire conduit module 10, and its structure is a continuous pipe with a predetermined diameter. In one embodiment, the main conduit 11 is made of a corrosion-resistant polymer material pipe with an outer diameter of 10-20 mm and a wall thickness of 1-2 mm, such as modified nylon pipe or polytetrafluoroethylene pipe, to ensure its long-term chemical stability and sufficient compressive strength in the concrete environment. The first and last ends of the main conduit 11 are respectively connected to the media supply module 20, forming a circulation loop for delivering responsive repair media.

[0034] A predictive pressure-relieving microchannel 12 branches off from the wall of the main channel 11, with a diameter smaller than the main channel 11, for example, 3-5 mm. The other end of this microchannel extends to the vicinity of the pressure-bearing surface (i.e., the water-facing side) of the enclosure structure. At the end of this microchannel, an electrically controlled miniature solenoid valve 121 is installed. This valve 121 is a normally closed solenoid valve that receives electrical signals from the sensing and control module 30. In one specific implementation, a miniature solenoid valve with a working voltage of 24V DC, a valve body diameter of 2 mm, and an opening response time of less than 50 milliseconds is selected. The control cable of valve 121 is bundled together with the pipeline of the channel module 10 and uniformly led out to the ground for connection with the sensing and control module 30.

[0035] The repair micro-vein 13 branches off from the main vein 11, with its end sealed by a pressure-sensitive soluble end cap 131. This end cap 131 is designed to enable passive release of the repair medium. In one specific embodiment, the end cap 131 is hot-pressed from a specific ratio of polyvinyl alcohol (PVA) and inert filler. By adjusting the degree of polymerization, degree of hydrolysis of the PVA, and the proportion of filler, its rupture threshold under internal and external pressure differentials can be precisely set. For example, the end cap 131 is structurally damaged when the external water pressure exceeds the internal circulating pressure of the main vein 11 by 0.2 MPa, thus creating an outlet for the repair medium.

[0036] The sensing and control module 30 is the decision-making and control center of the entire system. This module includes a distributed sensing subunit and an intelligent control subunit. Physically, the distributed sensing subunit mainly comprises an integrated distributed optical fiber (not shown separately in the figure) and a ground-based fiber optic demodulator. This integrated distributed optical fiber functions as both distributed strain sensing and distributed temperature sensing. During installation, the fiber is wound with a high-temperature resistant epoxy resin adhesive at a predetermined pitch or tightly bonded to the outer wall of the main network 11 along a straight direction to ensure that strain of the enclosure structure and temperature changes within the main network are transmitted to the fiber without loss. The fiber optic demodulator calculates the strain and temperature values ​​at every location along the entire fiber in real time by emitting laser pulses into the fiber and receiving and analyzing backscattered Rayleigh and Brillouin scattering signals.

[0037] In another embodiment of the invention, the distributed sensing subunit can also be implemented using a quasi-distributed or discrete sensing scheme. For example, a series of fiber Bragg grating (FBG) strain sensors and temperature sensors, or vibrating wire strain gauges and thermistors, are discretely deployed at key stress concentration locations determined in advance through finite element analysis. These discrete sensors are connected to the data acquisition module of the intelligent control subunit via signal transmission cables. The intelligent control subunit obtains strain and temperature data at specific locations by polling each discrete sensor and estimates the regional state between sensors using a spatial interpolation algorithm, thus enabling the monitoring of key parts of the building envelope.

[0038] The hardware carrier of the intelligent control subunit is an embedded industrial computer or programmable logic controller (PLC). Internally, it is equipped with a central processing unit (CPU), data storage, a data interface (such as an Ethernet interface) for communication with the fiber optic demodulator, and a digital output (DO) card for outputting control signals. It receives a continuous data stream from the fiber optic demodulator, executes internally programmed predictive stress relief mode and self-healing repair mode algorithms, and, based on the algorithm's calculation results, outputs open or closed control level signals to a specific electrically controlled micro-sowary valve 121 via the DO card.

[0039] The media supply module 20, located on the ground, mainly consists of a reservoir, a low-power circulation pump, and a pressure sensor. The reservoir holds the responsive repair media. The low-power circulation pump, such as a low-flow peristaltic pump, provides a stable, low-pressure drive for the circulation of the repair media within the main network 11, maintaining the circulation pressure between 0.1 and 0.3 MPa. This low-pressure circulation avoids impact on the pressure-sensitive soluble end cap 131 while ensuring the repair media is always available. The pressure sensor monitors the pressure in the circulation loop in real time, feeding the data back to the intelligent control subunit to determine if the pipeline is blocked or has suffered significant damage.

[0040] The responsive remediation medium is a two-component system, unique in that the two components are physically isolated before injection into the system. In a specific, non-limiting embodiment, component A of the medium is a liquid polyether polyol, and component B is a polyphenylene isocyanate (PAPI) encapsulated in microcapsules. The microcapsule wall material encapsulating component B is a polymeric material that is stable in an anhydrous environment but swells or ruptures due to osmotic pressure upon contact with water. During circulation within the main network 11, components A and B coexist in the polyol liquid without contact, and the medium as a whole exhibits a low-viscosity liquid state. When the medium flows out from the damaged end cap 131 and comes into contact with external groundwater, water molecules cause the microcapsule wall material to rupture, releasing the internal component B (PAPI). The PAPI rapidly polymerizes with the surrounding water and component A (polyol), forming a cross-linked polyurethane solid, thereby sealing the leakage channel.

[0041] The responsive repair medium is not limited to the polyurethane system described above. In other embodiments, it can also be a two-component epoxy resin system, wherein component A is an epoxy resin prepolymer and component B is a curing agent, which is also physically isolated by microcapsules. Alternatively, it can be an acrylate gel system, wherein the activator-coagulant is a mixture of an initiator and a accelerator, which is encapsulated in a water-ruptureable capsule. When the capsule ruptures, the initiator and accelerator are released, rapidly initiating the polymerization of acrylate monomers to form a gel solid with high elasticity and waterproof properties.

[0042] See attached document Figure 1 Appendix Figure 3 and attached Figure 4 , attached Figure 3 This is a flowchart illustrating the control logic of a predictive stress-relieving mode according to an embodiment of the present invention. Figure 4 This is a control logic flowchart of a self-healing repair mode according to an embodiment of the present invention.

[0043] The sensing and control module 30 is the decision-making and command center of the entire system, and it physically includes a distributed sensing subunit and an intelligent control subunit.

[0044] The core components of the distributed sensing subunit are an integrated distributed optical fiber and a fiber optic demodulator that works in conjunction with it. During deployment, the integrated distributed optical fiber is tightly fixed to the outer wall of the main network 11 to ensure that the strain of the enclosure structure and the temperature of the fluid inside the main network 11 can be accurately and without delay transmitted to the fiber. The fiber optic demodulator is located on the ground and connected to the port of the pre-embedded optical fiber via a fiber optic connector. This demodulator emits laser pulses of specific frequency and width into the optical fiber and receives and analyzes the signals of backscattered Brillouin and Rayleigh scattered light generated in the fiber. Based on the frequency shift, time shift, and intensity changes, it calculates the strain and temperature values ​​corresponding to each spatial sampling point along the fiber path in real time, thereby forming continuous strain and temperature field data.

[0045] The intelligent control subunit is the hardware carrier that executes the control algorithm. In one specific embodiment, it is an embedded industrial computer or a programmable logic controller (PLC). Internally, this subunit includes a central processing unit, a data memory, a high-speed data interface (e.g., an Ethernet interface) for receiving data from the demodulator, and a digital output (DO) interface for outputting control commands. This subunit receives continuous strain and temperature field data streams from the fiber optic demodulator and combines this data with spatial location information. Store after binding.

[0046] The intelligent control subunit processes the acquired strain field data by running an internally pre-defined stress relief mode algorithm. Its specific workflow is shown in the attached figure. Figure 3 As shown. In each data acquisition cycle, the sub-unit targets each monitoring point. The strain values ​​acquired in real time Compared with the critical strain threshold corresponding to that location that is pre-stored in the database. A comparison is then made. Simultaneously, the strain rate is obtained by performing a difference operation between the current strain value and the strain value at the previous moment. and compared with a preset strain growth rate threshold. Compare them.

[0047] The results of these two comparisons are determined by a logical AND gate. Only when... and When both conditions are met, the pressure relief valve at that location is activated. The output value is 1 only when... When the value is 1, the intelligent control subunit sends a signal to the location via its digital output interface. The electrically controlled miniature solenoid valve 121 sends an opening command (e.g., outputs a 24V DC level signal), causing the valve to open and release local water pressure. If any condition is not met, then... A value of 0 indicates that the valve remains closed or has been instructed to close.

[0048] Meanwhile, the intelligent control subunit processes the acquired temperature field data by running a self-healing repair mode algorithm; its specific workflow is shown in the attached figure. Figure 4 As shown. The sub-unit is each monitoring point. Maintain a background reference temperature This value is based on a preset time window preceding the current moment. The moving average is calculated from historical temperature data over a period of time (e.g., 10 minutes). This method effectively filters out slow, general temperature drift caused by seasonal or diurnal variations.

[0049] In each data acquisition cycle, the subunit will acquire the temperature value in real time. Compared with the background reference temperature at this point Compare and calculate the temperature difference When external groundwater seeps into the retaining structure through cracks and comes into contact with the wall of the main network 11 pipe, its temperature will be lower than that of the circulating medium inside the main network, causing a rapid local cooling. The calculated temperature difference... Temperature difference greater than the preset trigger threshold (For example, at 2 degrees Celsius), the intelligent control subunit determines the position. A leakage event occurred. The subunit records the time, location, and temperature difference of the leakage event in the system log and issues an alarm. The physical sealing process of the leakage is accomplished by the passive rupture of the pressure-sensitive soluble end cap 131 and the automatic solidification of the responsive repair medium. In this mode, the control unit mainly undertakes the functions of monitoring, locating, and alarming.

[0050] In a preferred embodiment, the intelligent control subunit further includes a data interface for data interaction with the construction site's Building Information Modeling (BIM) platform. Through this interface, all monitoring points... The spatial coordinates of the components precisely correspond to the 3D digital model of the enclosure structure in the BIM model. When the intelligent control subunit detects any strain or temperature anomalies, in addition to recording data and executing control commands, it can also highlight the location, type, and severity of the event in real time at the corresponding location in the BIM model using 3D visualization. This method provides engineering managers with an intuitive risk situation awareness interface, significantly improving the efficiency and accuracy of information transmission. See attached document Figure 1The media supply module 20 is an independent functional unit located on the ground, used to provide and circulate responsive repair media for the entire system. In practice, this module is housed in a protected outdoor cabinet to ensure its internal components are protected from environmental factors and operate stably. This module mainly includes a storage tank 21, a low-power circulation pump 22, and a pressure sensor 23.

[0051] The reservoir 21 is used to contain pre-prepared responsive remediation media. The reservoir is made of 304 stainless steel, and its inner wall is polished to reduce media adhesion and ensure chemical inertness. A sealed cap is provided on the top of the reservoir, equipped with a breather valve containing a desiccant to balance internal and external air pressure during liquid level changes, while preventing moisture from the outside air from entering the reservoir and affecting the stability of the remediation media. A liquid level sensor is also installed on the tank to monitor the amount of media inside in real time and sends an alarm signal to the sensing and control module 30 when the liquid level falls below a preset threshold.

[0052] A micro-powered circulation pump 22 is connected in series in the loop between the reservoir 21 and the main network 11 to power the circulation of the responsive repair medium. In one specific implementation, an industrial-grade peristaltic pump is selected as the circulation pump. The advantage of using a peristaltic pump is that the fluid only contacts the pump tubing, avoiding cross-contamination caused by direct contact between the medium and the pump body, thus ensuring the chemical purity of the repair medium. The pump's flow rate is set at a low, constant value, and the resulting circulation pressure is precisely controlled within the range of 0.1 to 0.3 MPa. This low-pressure circulation state ensures that the medium can flow stably throughout the main network 11, while its pressure is insufficient to trigger the rupture of the pressure-sensitive soluble end cap 131 at the end of the repair micro-network 13.

[0053] Pressure sensor 23 is installed on the pipeline between the outlet of the micro-power circulating pump 22 and the inlet of the main network 11 to monitor the actual working pressure of the circulation loop in real time. The sensor transmits the monitored pressure signal to the intelligent control subunit in real time. This pressure data has a dual function: first, to verify whether the system is in a normal circulation state, i.e., whether the pressure value fluctuates stably within the preset range of 0.1 to 0.3 MPa; second, to perform fault diagnosis when the system malfunctions. For example, a sustained and significant drop in pressure indicates that the main network 11 or its connecting pipelines may have suffered serious damage or leakage; an abnormally high pressure indicates that there may be a blockage in the circulation loop.

[0054] Inside the media supply module 20, the liquid storage tank 21, the micro-power circulation pump 22, and the pressure sensor 23 are connected as a whole through corrosion-resistant pipes and valves (such as manual ball valves). The manual ball valve allows for physical isolation between the media supply module 20 and the underground network module 10 when maintaining or replenishing the media, thus improving the maintainability of the system.

[0055] The responsive remediation medium is a composite fluid that triggers a phase change under specific conditions to achieve a sealing function. The medium is designed to maintain a stable low-viscosity liquid state when circulating within the main network 11, while rapidly undergoing an in-situ polymerization reaction upon contact with external groundwater, transforming into a solid substance.

[0056] In one specific, non-limiting embodiment, the responsive repair medium is a microencapsulated two-component polyurethane system. The system consists of component A, which acts as a liquid phase carrier, and component B, which is physically isolated from the liquid phase.

[0057] Component A is the continuous phase of the medium, and its main component is polyether polyol. To adjust the reactivity and enhance system stability, a certain amount of catalyst (e.g., dibutyltin dilaurate) and foam stabilizer (e.g., silicone oil surfactant) may also be added to component A. In the unactivated state, component A is a clear liquid with low viscosity.

[0058] Component B serves as the activation-coagulation core of this medium, and its main component is polymethylene polyphenyl isocyanate (PAPI). Before being added to component A, component B is encapsulated in individual microcapsules, achieving physical isolation from component A. The shell wall of the microcapsules is made of a water-sensitive polymer material, such as urea-formaldehyde resin or modified gelatin. This wall material maintains structural integrity and chemical stability in the non-aqueous polyol environment of component A, but upon contact with water molecules, it rapidly swells and ruptures due to changes in osmotic pressure or hydrolysis.

[0059] During normal system operation, the responsive repair medium containing components A and B circulates stably within the main network 11. Due to the isolation effect of the microcapsule wall material, the two components do not come into contact with each other and do not undergo chemical reactions. When leakage occurs in the enclosure structure, groundwater intrusion causes the pressure-sensitive soluble end cap 131 at the end of the repair micronetwork 13 to rupture, and the repair medium flows out from the rupture.

[0060] At the outflow point, the microcapsules in the remediation medium come into contact with external groundwater. Water molecules rapidly break down the wall material of the microcapsules, releasing the encapsulated component B (isocyanate). The released component B simultaneously undergoes rapid chemical reactions with two substances: first, it reacts with the surrounding groundwater (generating amines and carbon dioxide gas), and second, it reacts with component A (polyol) in the medium. These two parallel polymerization and cross-linking reactions cause the medium to expand and foam within minutes, ultimately forming a semi-rigid polyurethane consolidation with high bonding strength and low permeability, which fills and seals the leakage path.

[0061] In a specific implementation of this invention, the system workflow also includes an initial calibration step. This step is performed after the concrete pouring of the retaining structure is completed and reaches its design strength, but before the foundation pit is extensively excavated or subjected to significant external load disturbances. In this state, the sensing and control module 30 is activated to continuously collect data on the strain field and temperature field of the entire line for at least 24 hours. The average data value under the steady-state condition during this period is set as the value for each monitoring location. initial zero-point strain and initial reference temperature All subsequent real-time strain values ​​are changes relative to this initial zero-point strain, while the subsequent background reference temperature... The calculations also use this initial reference temperature as the starting point.

[0062] See attached document Figure 3 The figure illustrates the workflow of the predictive stress relief mode in this invention. This process aims to release excessively high local water pressure on the building envelope before structural failure occurs through proactive intervention. The specific steps are as follows: The intelligent control subunit continuously acquires real-time strain field data demodulated from the optical fibers deployed along the entire main network 11 from the distributed sensing subunit. For each spatial sampling point Upon receiving a new strain value, the intelligent control subunit performs a dual judgment.

[0063] The first judgment is to use the real-time strain value. With the data pre-stored in its database, and with that location Corresponding critical strain threshold Compare this critical strain threshold. It is a safety limit set in advance for different locations on the structure based on the design strength, material properties and safety specifications of the building envelope.

[0064] The second judgment is to calculate the real-time strain growth rate. and compared with a preset strain growth rate threshold. Comparison. The strain growth rate is compared with the current moment. The strain value and the time of the previous acquisition cycle The strain values ​​are differentiated and divided by the time interval. This is used for approximate calculation. This judgment is used to identify whether the stress state is stable or rapidly deteriorating.

[0065] The results of the two judgments above are processed through a logical function. A combined decision is made. This logic function ensures that the system only initiates intervention measures when the strain value at a certain location exceeds its safety limit and its growth rate also exceeds the warning threshold. The specific expression of this function is as follows: ; in, This indicates that the activation conditions have been met, and the predictive stress-relieving microchannel has been opened. This refers to the positional variable along the enclosure structure; It is a time variable; For distributed sensing subunits at time ,Location The real-time strain value measured at the location; Preset according to structural design parameters, and position The relevant critical strain threshold; This is the partial derivative of the real-time strain value with respect to time, i.e., the strain rate of increase; The preset strain growth rate threshold; For logical AND operator.

[0066] when When the calculation result is 1, the intelligent control subunit determines that the risk at that location has reached the intervention standard, and immediately sends a signal to the location via its digital output interface. The electrically controlled micro-sowary valve 121 at the location receives an opening command (e.g., outputting a continuous 24V DC level signal), and valve 121 opens, allowing localized high-pressure groundwater outside the building envelope to drain through the predictive pressure-relieving microchannel 12, thereby reducing the water pressure acting on the structure at that point. When the strain value falls back to a safe range or the rate of increase slows down, leading to... When the calculation result becomes 0, the intelligent control subunit sends a shutdown command, and valve 121 closes.

[0067] See attached document Figure 4 The figure illustrates the workflow of the self-healing repair mode in this invention. This process aims to automatically monitor and locate leaks, and then achieve self-healing sealing using a responsive repair medium. The specific steps are as follows: The intelligent control subunit continuously acquires real-time temperature field data demodulated from the optical fibers deployed along the entire main network 11 from the distributed sensing subunit. .

[0068] To eliminate interference from slow changes in ambient temperature (such as seasonal changes or day-night cycles), the intelligent control subunit provides each monitoring point with... Calculate and maintain a dynamic background reference temperature This value is based on a preset time window preceding the current moment. The moving average calculated from all historical temperature data over a period of time (e.g., 30 minutes).

[0069] In each data acquisition cycle, the intelligent control subunit calculates the real-time temperature value. relative to the background reference temperature at that point The decrease in temperature. When groundwater with a lower external temperature seeps into the main network 11 pipe wall through cracks in the retaining structure, it will cause a significant and rapid decrease in temperature at that location.

[0070] When the temperature drop exceeds the preset temperature difference trigger threshold (For example, at 2.0 degrees Celsius), the intelligent control subunit determines the position. A leakage event occurred. The subunit then records the location, time, ambient temperature, and background temperature of the event in the system log and triggers an audible and visual alarm to alert management. The physical sealing process of the leakage is achieved by the pressure difference between the external water pressure and the internal circulating pressure at the leak point, causing the pressure-sensitive soluble end cap 131 to rupture. This is then completed by the automatic outflow of the responsive repair medium and in-situ solidification reaction. In this mode, the main functions of the sensing and control module 30 are monitoring, location, and alarm.

[0071] The above-described embodiments are merely illustrative of the present invention. Any equivalent embodiments made by those skilled in the art, without departing from the scope of the technical features disclosed in the present invention, using partial modifications or alterations to the technical content disclosed in the present invention, shall still fall within the scope of the technical features of the present invention.

Claims

1. A seepage prevention control system for the retaining structure of deep foundation pits in subway stations in water-rich karst areas, characterized in that, include: The network module, pre-embedded within the enclosure structure, includes: a main network for circulating and delivering responsive repair media, and predictive pressure-relieving microchannels for actively releasing local water pressure; the network module is also used to perform leakage repair. A media supply module for containing and supplying the responsive remediation medium, which triggers solidification upon contact with groundwater; The sensing and control module, connected to the network module and the medium supply module, is used to monitor the strain and temperature of the enclosure structure, and control the network module to perform functions such as actively releasing local water pressure or repairing leaks based on the monitoring results.

2. The seepage prevention control system for deep foundation pit retaining structure of subway stations in water-rich karst areas according to claim 1, characterized in that, The sensing and control module includes: A distributed sensing subunit includes an integrated distributed optical fiber arranged along the entire main network, used to acquire strain field data of the enclosure structure and temperature field data inside the main network in real time. The intelligent control subunit, connected to the distributed sensing subunit, is used to process the strain field data to determine whether the predictive pressure relief microchannel needs to be opened, and to process the temperature field data to determine whether leakage has occurred.

3. The seepage prevention control system for deep foundation pit retaining structure of subway stations in water-rich karst areas according to claim 2, characterized in that: The intelligent control subunit processes the strain field data using a preset predictive stress relief mode algorithm. The activation condition for the predicted stress relief mode algorithm is: at a certain location in the building envelope. At this point, the actual strain value Greater than the critical strain threshold at this location And its strain growth rate Greater than the preset strain growth rate threshold ; When the activation condition is met, the intelligent control subunit is activated at this position. The predictive stress-relieving microchannel at the location.

4. The seepage prevention control system for deep foundation pit retaining structure of subway stations in water-rich karst areas according to claim 3, characterized in that, The activation condition of the predicted stress relief mode algorithm is determined by the following logical function. Make a judgment: ; in, This indicates that the activation conditions have been met, and the predictive stress-relieving microchannel has been opened. This refers to the positional variable along the enclosure structure; It is a time variable; For distributed sensing subunits at time ,Location The real-time strain value measured at the location; The critical strain threshold related to position z is preset based on the structural design parameters. This is the partial derivative of the real-time strain value with respect to time, i.e., the strain rate of increase; The preset strain growth rate threshold; For logical AND operator.

5. The seepage prevention control system for deep foundation pit retaining structure of subway stations in water-rich karst areas according to claim 2, characterized in that, The intelligent control subunit processes the temperature field data using a preset self-healing repair mode algorithm. The activation condition for the self-healing repair mode algorithm is: at a certain position in the main network. At that location, its background reference temperature With real-time temperature value The difference is greater than the preset temperature difference trigger threshold. Wherein, the background reference temperature The previous preset time window for the current moment The historical moving average temperature within the region.

6. The seepage prevention control system for deep foundation pit retaining structure of subway stations in water-rich karst areas according to claim 1, characterized in that, The network module includes: The main network is used for the cyclical delivery of the responsive repair medium; The micro-vessels are repaired and connected to the main vessel. A pressure-sensitive soluble end cap is provided at the end of the micro-vessels. The pressure-sensitive soluble end cap is destroyed when the pressure difference between the external groundwater seepage pressure and the internal pressure of the main vessel exceeds its rupture threshold, thereby causing the responsive repair medium to flow out.

7. The seepage prevention control system for deep foundation pit retaining structure of subway stations in water-rich karst areas according to claim 6, characterized in that, The network module also includes a predictive stress-relieving microchannel, at the end of which is equipped with an electrically controlled micro-solenoid valve; the electrically controlled micro-solenoid valve is electrically connected to the sensing and control module and is controlled by the module to open or close.

8. The seepage prevention control system for deep foundation pit retaining structure of subway stations in water-rich karst areas according to claim 1, characterized in that, The responsive repair medium provided by the media supply module has the following performance characteristics: The system circulates stably in a low-viscosity liquid state within the network module. Its interior contains an activator-coagulant that is physically isolated; Furthermore, when the responsive remediation medium comes into contact with groundwater, the physically isolated activator-coagulant is released, thereby undergoing an in-situ polymerization reaction to form a solidified product.

9. The seepage prevention control system for deep foundation pit retaining structure of subway stations in water-rich karst areas according to claim 7, characterized in that, The placement of the predictive stress-relieving microchannels is predetermined based on the stress concentration areas determined by the finite element analysis of the soil-rock interaction during the foundation pit excavation process.

10. A method for seepage control of the retaining structure of deep foundation pits for subway stations in water-rich karst areas, characterized in that, The system for implementing the seepage prevention control system for deep foundation pit retaining structures of subway stations in water-rich karst areas as described in any one of claims 1-9 includes the following steps: Predictive stress relief steps: The strain field of the enclosure structure is continuously monitored through the sensing and control module; when the strain value and strain rate increase at a certain location are detected to exceed a preset threshold at the same time, the local water pressure is actively released through the network module. Self-healing repair steps: The temperature field within the network module is continuously monitored by the sensing and control module; when the temperature drop at a certain location exceeds a preset threshold, it is determined that a leak has occurred at that location, and the responsive repair medium flows out through the network module, automatically solidifies upon contact with groundwater at the leak point, thereby sealing the leak channel.

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