Foundation pit air film structure safety monitoring system and method

Abstract

The present application relates to the field of construction engineering construction technology, provide a kind of foundation pit air film structure safety monitoring system and method, system includes: vibrating wire strain gauge, is laid in the key cable position of foundation pit air film structure periphery, for real-time acquisition cable stress data;Data acquisition module is connected with the vibrating wire strain gauge, for automatically collecting stress data according to preset time interval;Intelligent analysis platform is connected with the data acquisition module, for receiving stress data and calculating the stress variation of adjacent period, the stress variation is compared with preset threshold value;Early warning push module is connected with the intelligent analysis platform, when the stress variation exceeds preset threshold value, automatically push early warning information to preset terminal.The present application is by monitoring cable stress variation, correlation wind snow load dynamic adjustment acquisition frequency and alarm threshold, realize trend prediction early warning, change after-the-fact alarm into pre-control, significantly improve timeliness and reliability.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to a safety monitoring system and method for foundation pit air-supported membrane structures. Background Technology

[0002] With the deepening of urbanization and the increasing demands for environmental protection, air-supported membrane structures for foundation pits have become a new type of green construction technology, widely used in densely populated urban areas. This technology uses a highly elastic, low-thermal-conductivity membrane material to completely enclose the foundation pit, resembling an inflatable dome. This effectively suppresses dust and harmful gas emissions, reduces noise transmission, and mitigates the impact of severe weather. The air-supported membrane structure achieves self-support through the pressure difference between the inside and outside of the pit and is fixed to the ground perimeter via an inclined mesh anchoring system, offering significant advantages such as lightweight construction and reusability.

[0003] However, the dynamic response of air-supported membrane structures in foundation pits under wind and snow loads is complex, and the safety control requirements are high. According to relevant technical guidelines, the design of air-supported membrane structures in foundation pits requires working internal pressure design, initial morphology analysis, and load effect analysis. The wind load shape coefficient must be determined according to the "Code for Design of Building Structures" (GB50009). When calculating the internal forces and displacements of the cable and membrane parts caused by wind loads, the wind dynamic effect should be considered, and the wind vibration coefficient can be taken as 1.2 to 1.6. In areas with large snow loads, snow thickness sensors should be installed on the air-supported membrane structure in the foundation pit. However, the calculation of the snow load distribution coefficient still relies on empirical formulas in the code, which is difficult to reflect the non-uniform characteristics of actual snow drift and redistribution.

[0004] Existing research indicates that wind and snow loads pose a significant threat to the safety of air-supported membrane structures in foundation pits. Related studies analyzed the wind-induced motion and dynamic characteristics of the membrane under different flow field conditions and initial pretension, finding that increased wind speed significantly enhances the aerodynamic response of the membrane surface, while increased initial pretension weakens the response. Related simulation studies revealed the frictional slip effect between the cable and membrane. These studies found that considering the slip effect, the cable net constraint capacity weakens, and the membrane surface displacement significantly increases under uneven snow loads, even leading to localized cable-membrane separation. Other studies have shown that before and after snow slippage, the structural stress level abruptly increases to more than double its original value, and the displacement at the structural center point can increase by up to 59%, resulting in instantaneous and extreme structural deformation.

[0005] Despite the rapid development of air-supported membrane structures for foundation pits, systematic and intelligent monitoring research on their response to wind and snow loads remains relatively lacking. Traditional monitoring technologies mainly suffer from the following three types of technical deficiencies: (a) Structural bias in the selection of monitoring targets Traditional air-supported membrane monitoring technology for foundation pits mainly focuses on monitoring membrane surface pressure and displacement. According to relevant technical guidelines, foundation pit air-supported membranes should be equipped with differential pressure sensors and wind speed sensors; in areas with heavy snow loads, snow thickness sensors should be used. The monitoring and control system should ideally operate continuously, and key components should be redundantly configured. Related technologies, through pressure sensor linkage, automatically pressurize under extreme weather conditions, achieving automatic pressure regulation.

[0006] However, the selection of the aforementioned monitoring targets has fundamental technical flaws. Membrane pressure monitoring can only reflect the local stress state of the membrane surface and cannot characterize the overall stability of the structure; displacement monitoring has a significant lag, and when a significant displacement is detected, the structure is often already in a critical instability state. More importantly, traditional methods neglect the key mechanical indicator of cable stress. According to the "Technical Standard for Testing Building Membrane Structures," cable and tie rod tension directly reflects the internal force state of the membrane structure under sustained conditions and is an important indicator for evaluating the safety and applicability of membrane structure projects. As the main load-bearing component of air-supported membrane structures, the stress changes of cables can effectively reflect the overall impact of wind and snow loads on structural stability, but traditional methods have not yet established a wind / snow load response evaluation system based on cable stress.

[0007] (II) The passivity and lag of the monitoring and early warning mechanism Traditional monitoring technologies often employ fixed threshold alarm mechanisms, lacking the ability to proactively respond to sudden changes in environmental loads. Relevant technical guidelines stipulate that the control system should have an automatic alarm function when abnormal changes occur in the working air pressure within the foundation pit's air-supported membrane structure; however, the alarm threshold is fixed and does not consider the time-varying nature of environmental loads. In actual engineering projects, when the on-site wind force increases from level 2 to level 5 and the wind speed rises to 8.5 m / s within a short period, if fixed threshold monitoring is used, the system cannot promptly capture the abnormal trend in the structural response at the initial stage of the wind force change.

[0008] Furthermore, traditional methods lack the ability to predict and warn of trends. Air-supported membrane structures exhibit significant flexibility and nonlinearity under wind and snow loads, and stress changes show a clear cumulative effect over time. Traditional monitoring relies solely on the current state for assessment and cannot predict future stress trends based on historical data, resulting in insufficient timeliness of early warnings and hindering proactive risk control.

[0009] (iii) The disconnect between monitoring sensitivity and environmental load Traditional monitoring systems have fixed data acquisition frequencies and warning thresholds, failing to establish a dynamic correlation with changes in environmental loads. According to relevant technical guidelines, the wind speed sensor in the air-supported membrane structure of the foundation pit should be linked to the control system, and the pressure setting within the membrane should be determined through rigorous calculation and analysis. However, there is a lack of quantitative mapping between wind speed changes and monitoring sensitivity. When encountering sudden strong winds (level 5-6) or blizzards caused by cold air passage, fixed-frequency monitoring may miss critical stress change points—for example, at a wind speed of 8 m / s, the stress change in the cables can reach tens of megapascals in a short period, and fixed sampling intervals are insufficient to capture this dynamic evolution process. Fixed thresholds may also become ineffective due to sudden changes in environmental loads.

[0010] While traditional solutions propose immediately increasing the internal pressure of the air-supported membrane in the foundation pit when wind speeds reach level 6 or higher, the quantitative relationship between internal pressure adjustment and structural stress response remains unclear, and there is a lack of intelligent control strategies based on cable stress feedback. The disconnect between monitoring sensitivity and environmental loads leads to a significant reduction in the system's reliability under extreme weather conditions.

[0011] In civil engineering fields such as bridges and tunnels, vibrating wire strain gauges have been widely used for structural stress monitoring. Vibrating wire strain gauges reflect stress changes in the measured object by measuring changes in the vibration frequency of the steel wire. They feature high precision, good long-term stability, and strong anti-interference capabilities, and have been applied in many major projects. However, directly applying vibrating wire strain gauges to the monitoring of air-supported membrane cables in foundation pits presents technical challenges: First, there are differences in the mechanical properties of the monitored objects. Bridge cables are long-span suspension structures, mainly subjected to axial tension; while the air-supported membrane cables in the foundation pit are spatial mesh anchoring systems, which exhibit significant lateral vibration and cable-membrane coupling effects when subjected to wind loads, resulting in a more complex stress change mechanism.

[0012] Second, the coupling mechanism of environmental loads. Bridge structures mainly bear vehicle loads and wind loads, with snow loads having a relatively small impact; the air-supported membrane structure in the foundation pit simultaneously bears the coupling effects of wind loads, snow loads, and changes in internal pressure. The non-uniform load distribution caused by snow drift results in significant spatial differences in cable stress.

[0013] Third, there are special requirements for the timeliness of early warning. Bridge structural failures usually have a long development process, allowing for a certain early warning response time; however, air-supported membrane structures in foundation pits may experience instantaneous instability under extreme wind / snow loads (such as stress abrupt changes caused by snow slippage), requiring monitoring systems to have response capabilities at the minute or even second level.

[0014] The aforementioned technical obstacles prevent existing vibrating wire strain gauge technology from being directly applied to air-supported membrane structures in foundation pits. It is necessary to develop specialized intelligent monitoring methods that address the stress characteristics of air-supported membrane cables, the coupling mechanism of wind / snow loads, and the timeliness requirements for early warning.

[0015] In summary, traditional foundation pit air film monitoring technology faces the following pressing technical problems that need to be addressed: (i) How to establish a wind / snow load response assessment system based on cable stress, break through the limitations of traditional schemes that mainly rely on membrane pressure monitoring, and achieve real-time characterization of the overall structural stability. (ii) How to construct a dynamic monitoring mechanism under sudden changes in environmental load, solve the passivity of fixed threshold and fixed frequency monitoring, and achieve adaptive matching between monitoring sensitivity and changes in environmental load; (III) How to establish a stress trend prediction and early warning method to overcome the lag of the traditional post-event alarm mode and achieve early identification and control of risks. Summary of the Invention

[0016] The purpose of this invention is to solve at least one technical problem in the background art and to provide a safety monitoring system and method for foundation pit air-supported membrane structures.

[0017] To achieve the above objectives, the present invention provides a safety monitoring system for foundation pit air-supported membrane structures, comprising: Vibrating wire strain gauges are installed at key cable locations around the periphery of the air-supported membrane structure in the foundation pit to collect cable stress data in real time. The data acquisition module is communicatively connected to the vibrating wire strain gauge and is used to automatically acquire stress data at preset time intervals. The intelligent analysis platform is connected to the data acquisition module to receive stress data and calculate the stress change in adjacent time periods, and compares the stress change with a preset threshold. The early warning push module is connected to the intelligent analysis platform and automatically pushes early warning information to a preset terminal when the stress change exceeds a preset threshold. The preset threshold is determined based on the cable material properties and structural safety level, and the stress change is calculated as the difference between the stress value at the current moment and the stress value at the previous moment.

[0018] According to one aspect of the invention, the vibrating wire strain gauge is arranged on the key load-bearing cable of the inclined mesh anchoring system on the periphery of the air-supported membrane structure. The cable is connected to the air-supported membrane material by cable clamps, and the vibrating wire strain gauge is fixed to the anchoring end of the cable by a waterproof sealing kit.

[0019] According to one aspect of the present invention, the intelligent analysis platform establishes a correlation mapping relationship between stress change and wind speed and snow thickness; When the detected wind speed change exceeds a preset wind speed threshold and / or the snow thickness change exceeds a preset snow thickness threshold, the intelligent analysis platform automatically increases the data acquisition frequency and / or decreases the preset threshold.

[0020] According to one aspect of the present invention, the preset wind speed threshold is 2 m / s, and the preset snow accumulation threshold is 0.01 m; The automatic increase in data acquisition frequency is to increase it to twice the original data acquisition frequency, and the reduction of the preset threshold is to reduce it to 70%~80% of the original preset threshold.

[0021] According to one aspect of the present invention, the early warning push module pushes early warning information to a preset terminal through a wireless communication network. The early warning information includes: abnormal stress change, corresponding wind speed / snow load data, suggested disposal measures, and current safety status assessment of the air-supported membrane structure.

[0022] According to one aspect of the present invention, the intelligent analysis platform stores historical stress data and constructs stress time history curves; Based on the stress time history curve and numerical simulation results, the intelligent analysis platform predicts the stress development trend of the air-supported membrane structure under future loads. When the predicted stress value exceeds the allowable stress of the cable material or the preset safety factor limit, the intelligent analysis platform generates a prediction warning and pushes it to a preset terminal through the warning push module.

[0023] To achieve the above objectives, the present invention also provides a method for safety monitoring of an air-supported membrane structure in a foundation pit, comprising: S1. Install vibrating wire strain gauges at key cable locations around the perimeter of the air-supported membrane structure of the foundation pit to establish stress monitoring points; S2. Automatically collect cable stress data at each stress monitoring point at preset time intervals and transmit it to the intelligent analysis platform; S3. Calculate the stress change in adjacent time periods and compare it with the preset threshold in real time; S4. When the stress change exceeds a preset threshold, an early warning push is automatically triggered, and an early warning message is sent to a preset terminal; The preset threshold is determined based on the cable material properties and structural safety level, and the stress change is calculated as the difference between the stress value at the current moment and the stress value at the previous moment.

[0024] According to one aspect of the invention, it further includes: S5. Simultaneously monitor wind speed and snow thickness, establish a correlation analysis between stress change and environmental load parameters, and dynamically adjust the preset threshold and / or data acquisition frequency when the wind speed change exceeds the preset wind speed threshold and / or the snow thickness change exceeds the preset snow thickness threshold.

[0025] According to one aspect of the present invention, the preset threshold in step S3 is 50 MPa, and an early warning is triggered when the stress change exceeds 50 MPa.

[0026] According to one aspect of the invention, the dynamic adjustment in step S5 includes: When the wind speed change exceeds 2 m / s and / or the snow thickness change exceeds 0.01 m, the preset threshold will be reduced to 70%~80% of the original preset threshold, and / or the data acquisition frequency will be increased to twice the original frequency.

[0027] According to one aspect of the invention, step S6 is further included: A stress prediction model is established based on historical monitoring data and numerical simulation results; When the predicted stress value for a future period exceeds the allowable stress or safety factor limit of the material, an early warning is issued to achieve risk prevention and control.

[0028] According to the present invention, this invention addresses three major technical shortcomings of existing foundation pit air-supported membrane structure monitoring technologies: structural deviations of the monitored objects, passive and lagging early warning mechanisms, and a disconnect between monitoring sensitivity and environmental loads. It provides an intelligent monitoring system and method for the safety of foundation pit air-supported membrane structures. This invention establishes a wind / snow load response evaluation system based on cable stress. It collects key cable stress data in real time using vibrating wire strain gauges, using stress change (stress difference between adjacent time periods) as the core monitoring indicator. This shifts the monitoring focus from static absolute stress values ​​to dynamic stress change rates, thereby capturing the critical process of structural response. Simultaneously, it establishes a correlation mapping relationship between stress change and wind speed and snow thickness. When environmental loads change abruptly, it automatically increases the data acquisition frequency and lowers the early warning threshold, achieving adaptive matching between monitoring sensitivity and environmental loads. Furthermore, by combining time-history analysis of historical stress data with numerical simulation, it predicts future stress development trends and issues early warnings when predicted stress values ​​exceed the material's allowable stress or safety factor limits.

[0029] This invention overcomes the limitations of traditional methods that primarily rely on membrane pressure monitoring, achieving real-time characterization of the overall structural stability through cable stress monitoring. It overcomes the passivity of fixed threshold and fixed frequency monitoring, enabling dynamic adjustment of monitoring strategies and early risk control. It solves the technical obstacle of directly transplanting vibrating wire strain gauges to air-supported membrane cable monitoring, ensuring the representativeness and reliability of monitoring through anchorage placement and waterproof sealing design. Ultimately, it significantly improves the monitoring reliability and early warning timeliness of air-supported membrane structures in foundation pits during cross-seasonal construction, especially under extreme weather conditions, providing valuable emergency response time for on-site personnel and promoting the safe application and large-scale promotion of foundation pit air-supported membrane technology. Attached Figure Description

[0030] Figure 1 This schematic diagram illustrates a structural block diagram of a foundation pit air-supported membrane structure safety monitoring system according to an embodiment of the present invention. Figure 2The flowchart illustrates a safety monitoring method for an air-supported membrane structure in a foundation pit according to an embodiment of the present invention. Detailed Implementation

[0031] The invention will now be discussed with reference to exemplary embodiments. It should be understood that the described embodiments are merely intended to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0032] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment".

[0033] Figure 1 This diagram schematically illustrates a structural block diagram of a foundation pit air-supported membrane structure safety monitoring system according to one embodiment of the present invention. Figure 1 As shown, in this embodiment, the safety monitoring system for the foundation pit air-supported membrane structure includes: Vibrating wire strain gauges are installed at key cable locations around the periphery of the air-supported membrane structure in the foundation pit to collect cable stress data in real time. The data acquisition module is connected in communication with the vibrating wire strain gauge and is used to automatically acquire stress data at preset time intervals. The intelligent analysis platform communicates with the data acquisition module to receive stress data and calculate the stress change in adjacent time periods, and compares the stress change with a preset threshold. The early warning push module communicates with the intelligent analysis platform and automatically pushes early warning information to preset terminals when the stress change exceeds the preset threshold. The preset threshold is determined based on the cable material properties and structural safety level, and the stress change is calculated as the difference between the stress value at the current moment and the stress value at the previous moment.

[0034] In this embodiment, in the actual engineering application of air-supported membrane structures for foundation pits, wind and snow loads exhibit significant dynamic randomness and non-uniformity. Due to the lightweight and high flexibility of air-supported membrane structures, they are particularly sensitive to wind loads; the membrane surface is prone to vibration, fluttering, and even localized deformation under wind-induced forces. Snow loads tend to drift and redistribute at points of change in membrane curvature, leading to localized accumulation and stress concentration. More importantly, these environmental loads are not statically constant but evolve continuously over time, especially under extreme conditions such as cold air passage or blizzards, where load intensity may change abruptly within a short period. Therefore, simply monitoring the absolute stress value at a single moment is insufficient to effectively assess the structural safety status—even if the current stress value does not exceed the material's allowable stress, a rapid rate of stress change indicates that the structure may be undergoing a critical process of instability.

[0035] Based on this, this invention employs vibrating wire strain gauges deployed at key cable locations on the periphery of the air-supported membrane structure in the foundation pit. By acquiring real-time cable stress data, the dynamic mechanical response of the structure under environmental loads is obtained. Cables were chosen as the monitoring object because, as the core load-bearing component of the inclined mesh anchoring system, their stress changes can comprehensively reflect the overall stress state of the membrane surface and the collaborative performance of the anchoring system. Compared to directly monitoring local pressure or displacement of the membrane surface, cable stress better characterizes the overall stability of the structure. Vibrating wire strain gauges reflect stress changes by measuring changes in the vibration frequency of the steel wire, and are characterized by high precision, good long-term stability, and strong anti-interference ability, making them suitable for long-term monitoring in complex outdoor environments such as foundation pit air-supported membrane structures.

[0036] The data acquisition module automatically collects stress data measured by vibrating wire strain gauges at preset time intervals, ensuring the continuity of monitoring and the comparability of data. After receiving the stress data, the intelligent analysis platform calculates the stress change between adjacent time periods, that is, the difference between the stress value at the current moment and the stress value at the previous moment. The technical significance of this calculation method is that it shifts the monitoring focus from whether the absolute value of stress exceeds the limit to whether the rate of stress change is abnormal, thereby capturing the dynamic characteristics of the structural response. For example, in the early stage of a sudden change in wind load, even if the absolute value of stress has not yet reached a dangerous level, if the stress change exceeds a preset threshold, it indicates that the structure is rapidly responding to changes in external loads, posing a potential risk of instability, and requiring early intervention.

[0037] The preset thresholds are determined based on the cable material properties and structural safety levels, reflecting the alignment between monitoring standards and structural safety requirements. Cables of different materials, specifications, and importance have varying safety margins and early warning sensitivity requirements. By setting differentiated preset thresholds, both frequent false alarms due to excessively low thresholds and missed alarms due to excessively high thresholds are avoided. When the stress change exceeds the preset threshold, the early warning push module automatically pushes early warning information to preset terminals, achieving full automation from data collection and analysis to early warning issuance. This eliminates the need for real-time manual monitoring, significantly improving the timeliness and reliability of monitoring.

[0038] In this embodiment, by combining cable stress monitoring with stress change analysis, real-time perception of the dynamic response of the foundation pit air-supported membrane structure under wind and snow loads is achieved. By calculating the difference between adjacent time periods, the time-varying characteristics of environmental loads are transformed into quantifiable monitoring indicators, enabling the system to issue early warnings at the initial stage of the critical process of structural instability, rather than waiting until significant deformation or failure occurs before alarming, thus gaining valuable emergency response time for on-site personnel. Through personalized setting of preset thresholds and automatic early warning mechanisms, the monitoring sensitivity is adapted to the structural safety level, and the monitoring process can be operated unattended, reducing the cost of manual monitoring and improving the engineering practicality of the monitoring system.

[0039] Furthermore, according to one embodiment of the present invention, the vibrating wire strain gauge is arranged on the key load-bearing cable of the inclined mesh anchoring system on the periphery of the air-supported membrane structure. The cable is connected to the air-supported membrane material by cable clamps, and the vibrating wire strain gauge is fixed to the anchoring end of the cable by a waterproof sealing kit.

[0040] In this embodiment, in the engineering application of air-supported membrane structures in foundation pits, the connection nodes between the cables and the air-supported membrane material are critical points for mechanical transfer and also weak links in structural safety. The cables are connected to the air-supported membrane material through cable clamps, transferring the membrane tension to the anchoring system; at the same time, the cable anchoring ends bear the concentrated forces generated by the membrane tension and external loads, making them the areas with the most complex stress states.

[0041] Based on this, the placement of vibrating wire strain gauges has a clear technical focus: they are placed on the key load-bearing cables of the inclined mesh anchoring system on the periphery of the air-supported membrane structure. Specifically, the vibrating wire strain gauges are fixed to the cable anchoring end by a waterproof sealing kit.

[0042] In this embodiment, the cable anchoring end is the convergence point of membrane tension and anchoring system reaction force. The stress state at this location directly reflects the cable tension level and the cooperative working performance of the membrane surface and anchoring system. Compared to being located in the middle section of the cable or on the membrane surface, the anchoring end is better able to capture extreme changes in cable tension and avoid monitoring distortion caused by cable clamp slippage or membrane creep.

[0043] The vibrating wire strain gauge is secured by a waterproof sealing kit made of weather-resistant material. This kit effectively blocks moisture, dust, and corrosive chemicals from the construction environment, protecting the internal steel wire and electromagnetic coil of the strain gauge. In rainy, snowy, or high-humidity conditions, this ensures long-term stable operation of the monitoring equipment, maintains measurement accuracy and data continuity, and reduces equipment failure rates caused by environmental corrosion.

[0044] The cable anchorage end is typically located at the bottom of the air-supported membrane structure, close to the ground or construction work surface. Compared to high-altitude installation, this location facilitates construction, installation, and subsequent maintenance. Vibrating wire strain gauges are installed at the anchorage end using a clamp-on or sleeve-type method, requiring no structural modifications to the cable body and not affecting the overall stress system of the air-supported membrane structure. When calibration or replacement is needed, the sealing kit can be directly disassembled for operation, reducing maintenance costs throughout the entire lifecycle.

[0045] In this embodiment, by placing vibrating wire strain gauges at the critical stress-bearing location of the cable anchorage and equipping them with waterproof sealing kits, a balance is achieved between representativeness of the monitoring location, reliability of equipment protection, and feasibility of engineering implementation. This ensures that the cable stress monitoring data accurately reflects the overall safety status of the structure, guarantees the long-term stable operation of the monitoring equipment in complex construction environments, and also takes into account the economy and convenience of installation and maintenance, thereby enhancing the engineering practical value of the intelligent monitoring system.

[0046] Furthermore, according to one embodiment of the present invention, the intelligent analysis platform establishes a correlation mapping relationship between stress change and wind speed and snow thickness; When the detected wind speed change exceeds the preset wind speed threshold and / or the snow thickness change exceeds the preset snow thickness threshold, the intelligent analysis platform automatically increases the data collection frequency and / or lowers the preset threshold.

[0047] In this embodiment, during the monitoring of the air-supported membrane structure in the foundation pit, wind load and snow load serve as external excitation sources. Their intensity and changes directly determine the response characteristics of the structure. However, there are essential differences in their mechanisms of action and manifestations: wind load has significant dynamics and directionality, and the structure responds rapidly when the wind speed changes abruptly; snow load, on the other hand, has cumulativeity and non-uniformity, and changes in snow thickness reflect the load redistribution process.

[0048] Traditional monitoring systems treat wind speed, snow depth, and structural response as independent variables, setting fixed thresholds and sampling frequencies for each. This fails to establish a quantitative correlation among the three, leading to a disconnect between monitoring sensitivity and changes in environmental load. When wind speed or snow depth has not yet reached a dangerous level, but structural stress is already approaching a critical point due to response lag, the system cannot provide early warning. Alternatively, when environmental load fluctuates drastically, the fixed sampling frequency may miss critical response points, and the fixed threshold may become ineffective because it does not consider the time-varying nature of the load.

[0049] Based on this, the core function of the intelligent analysis platform in this invention lies in establishing a correlation mapping relationship between stress changes and wind speed changes, as well as snow thickness changes. The technical essence of this correlation mapping relationship is to construct a stress response model using historical monitoring data and numerical simulations, quantifying the transfer function between changes in environmental load parameters and structural stress changes. When the detected wind speed change exceeds a preset wind speed threshold and / or snow thickness change exceeds a preset snow thickness threshold, the intelligent analysis platform automatically executes two dynamic adjustment strategies based on this correlation mapping relationship: Strategy 1: Increase data acquisition frequency. Shorten the original fixed acquisition interval to improve the monitoring time resolution, capture subtle fluctuations in stress response, and avoid missing key change nodes.

[0050] Strategy 2: Lower the preset threshold. Lower the stress change warning threshold from the first-level threshold to the more stringent second-level threshold, so that the system can trigger the warning earlier when there are sudden changes in environmental load, and achieve dynamic matching between sensitivity and risk level.

[0051] In this embodiment, by establishing a correlation mapping between stress changes and environmental load parameters, dynamic adaptation of the monitoring strategy can be achieved. When the environmental load shows a sudden change trend, the system can predict the potential risks of structural response and adjust the monitoring sensitivity in advance, rather than passively waiting for the absolute stress value to exceed the limit. This mechanism can effectively solve the problem of insufficient adaptability of fixed thresholds and fixed frequencies under extreme weather conditions, transforming post-event alarms into process warnings, and significantly improving the monitoring reliability and warning timeliness of the foundation pit air-supported membrane structure under wind and snow loads.

[0052] Furthermore, according to one embodiment of the present invention, the preset wind speed threshold is 2 m / s, and the preset snow accumulation threshold is 0.01 m; The data acquisition frequency is automatically increased to twice the original frequency, and the preset threshold is reduced to 70% to 80% of the original threshold.

[0053] In this embodiment, the setting and dynamic adjustment of the early warning threshold in the intelligent monitoring system for the foundation pit air-supported membrane structure directly affect the monitoring sensitivity and false alarm rate control. This invention achieves the quantification and optimization of the monitoring strategy through preset specific values ​​and a dynamic adjustment mechanism. The preset wind speed threshold is set at 2 m / s, which is the critical wind speed change determined based on the "Code for Design of Building Structures" and experience in wind-resistant design of air-supported membrane structures. When the wind speed change exceeds 2 m / s, it indicates a significant increase in wind force in a short period (e.g., a sudden increase from level 2 to level 4), and the air-supported membrane structure will face sudden wind load, requiring the activation of high-frequency monitoring and sensitive early warning. The preset snow accumulation threshold is set at 0.01 m, corresponding to the snow thickness change from light to moderate snow, reflecting the beginning of significant snow drift and redistribution effects, and is a critical value at which the snow load risk significantly increases.

[0054] The system automatically doubles the data acquisition frequency, improving the monitoring time resolution by two times when environmental loads change abruptly. This allows it to capture subtle fluctuations in stress response and avoid missing critical change points. For example, the original 30-minute acquisition interval is shortened to 15 minutes, significantly enhancing the system's timeliness in responding to wind / snow loads. The preset threshold is lowered to 70%–80% of the original. In the early stages of environmental load changes, even if the stress change has not yet reached the original first-level threshold (50 MPa), an early warning is triggered as long as it exceeds the adjusted second-level threshold (e.g., 35 MPa–40 MPa). The core value of this adjustment mechanism lies in providing early warning, shifting the warning trigger point forward and giving on-site management personnel more time for emergency response, rather than waiting until the stress accumulates to a dangerous level before issuing an alarm.

[0055] In this embodiment, by quantifying preset thresholds and employing dynamic adjustment strategies, an adaptive match between monitoring sensitivity and environmental load risk levels is achieved. This avoids the failure risk of fixed thresholds under extreme conditions and prevents frequent false alarms caused by excessively low thresholds, thus optimizing the operational efficiency and early warning reliability of the monitoring system while ensuring structural safety.

[0056] Furthermore, according to one embodiment of the present invention, the early warning push module pushes early warning information to a preset terminal through a wireless communication network. The early warning information includes: abnormal stress change, corresponding wind speed / snow load data, suggested disposal measures, and current safety status assessment of the air-supported membrane structure.

[0057] In this embodiment, in the actual engineering application of air-supported membrane structures for foundation pits, the efficiency and completeness of early warning information transmission directly affect the emergency response speed and accuracy of on-site personnel. Traditional monitoring systems often suffer from problems such as limited information, transmission delays, and limited receiving terminals. For example, they may only send simple threshold exceedance alerts without providing specific numerical values ​​and environmental context for the abnormal data, making it difficult for on-site personnel to quickly assess the risk level; or they may rely on wired network transmission, which can lead to signal instability in the complex environment of foundation pit construction sites, resulting in the loss of early warning information.

[0058] Based on this, the early warning push module in this invention uses a wireless communication network as the transmission medium to push early warning information to preset terminals. The wireless communication network includes mobile communication networks (4G / 5G), wireless local area networks (Wi-Fi), or low-power wide area networks (LoRa / NB-IoT), which can adapt to the actual conditions of difficult wiring and variable environment at the foundation pit construction site, ensuring reliable transmission of early warning information under complex working conditions and avoiding the risk of wired network interruption due to construction machinery rolling, earthwork excavation, etc.

[0059] The design of early warning information follows a four-dimensional structure: data, background, countermeasures, and assessment. The abnormal stress change is provided with specific numerical values ​​(e.g., stress change of 52 MPa at monitoring point 3), enabling on-site personnel to accurately determine the location and extent of the anomaly. Corresponding to wind speed / snow load data, the environmental load parameters when the warning is triggered are pushed synchronously (e.g., current wind speed 8.5m / s, wind force level 4) to help determine the cause of the anomaly and the type of load; Recommended measures, based on the pre-set emergency plan, provide targeted operational guidance (e.g., recommend checking the tightness of the anchorage clamps at the No. 3 cable and, if necessary, initiating the air-film internal pressure boosting procedure) to shorten decision-making time; The current safety status assessment of the air-supported membrane structure, based on data from various monitoring points, provides an overall safety level determination (e.g., if the structure is in a yellow alert state, inspections need to be strengthened), to avoid overreaction to local anomalies or the overall risk being overlooked.

[0060] In this embodiment, reliable and real-time transmission of early warning information is achieved through a wireless communication network, overcoming the environmental limitations of wired networks at construction sites. Through structured information design, raw monitoring data is transformed into decision support information that can directly guide emergency response, significantly improving the practical value and response efficiency of early warning, reducing the risk of delays in response due to poor information transmission or incomplete content, and ensuring the construction safety of the foundation pit air-supported membrane structure under extreme working conditions.

[0061] Furthermore, according to one embodiment of the present invention, the intelligent analysis platform stores historical stress data and constructs stress time history curves; The intelligent analysis platform predicts the stress development trend of air-supported membrane structures under future loads based on stress time history curves and numerical simulation results. When the predicted stress value exceeds the allowable stress of the cable material or the preset safety factor limit, the intelligent analysis platform generates a prediction warning and pushes it to the preset terminals through the warning push module.

[0062] In this embodiment, during the long-term service of the air-supported membrane structure in the foundation pit, the effects of wind and snow loads have significant cumulative effects and periodic characteristics. The early warning mechanism of traditional monitoring systems is based solely on the stress state at the current moment, which is a reactive mode. When stress exceeds the limit or the rate of change is abnormal, the structure is often already in a critical instability state or undergoing a rapid deterioration process. The early warning time window obtained by on-site personnel is extremely limited, making it difficult to implement effective pre-control measures.

[0063] Based on this, the core function of the intelligent analysis platform in this invention lies in realizing a paradigm shift from post-event alarm to pre-event prevention and control. Its technical implementation path is divided into three stages: Phase 1: Historical Data Accumulation and Time-History Curve Construction. The intelligent analysis platform continuously stores historical stress data from each monitoring point, constructing stress time-history curves. These curves not only record the trajectory of the absolute stress value over time but also implicitly reveal the structural response patterns under different combinations of environmental loads, including vibration attenuation characteristics under wind loads, stress growth rates during snow load accumulation, and stress recovery cycles after extreme weather events. This time-history data forms the training basis for the predictive model, enabling the platform to identify periodic patterns and anomalous deviations in structural response.

[0064] Phase Two: Numerical Simulation and Trend Extrapolation. The intelligent analysis platform combines stress time history curves with numerical simulation results to predict the stress development trend of the air-supported membrane structure under future loads. The numerical simulation establishes a three-dimensional mechanical model of the air-supported membrane structure based on the finite element method, inputting future weather forecast parameters (wind speed, wind direction, snowfall) as boundary conditions to calculate the evolution of the structural response. By comparing historical measured data with numerical simulation results, the platform corrects the model parameters, gradually approximating the predicted results to real-world conditions, achieving a dual-engine prediction system driven by data and based on a physical model.

[0065] Phase Three: Prediction, Early Warning, and Risk Control. When the prediction results indicate that the stress value at a future moment will exceed the allowable stress of the cable material (such as the design value of tensile strength) or the preset safety factor limit (such as a safety factor lower than 1.5), the intelligent analysis platform generates a prediction and early warning message in advance and pushes it to preset terminals through the early warning push module. This early warning message includes the predicted time point of exceeding the limit, the predicted peak stress, and suggested pre-emptive measures (such as pre-pressurization, local reinforcement, suspension of high-risk operations, etc.), enabling on-site personnel to receive warnings hours or even days before the risk actually occurs, achieving proactive risk avoidance rather than reactive response.

[0066] In this embodiment, by using time-history analysis of historical data and forward-looking calculations of numerical simulations, the monitoring system's function is upgraded from state perception to trend prediction, significantly extending the lead time for early warnings. By using a dual determination of allowable material stress and safety factor limits, both structural strength safety and stability safety are taken into account. Through the structured delivery of predictive and early warning information, a scientific basis for on-site management is provided, realizing the forward shift of the safety management of the foundation pit air-supported membrane structure and greatly improving the risk prevention and control capabilities and construction safety assurance level under extreme weather conditions.

[0067] Furthermore, to achieve the above objectives, the present invention also provides a method for monitoring the safety of an air-supported membrane structure in a foundation pit based on the aforementioned foundation pit air-supported membrane structure safety monitoring system, such as... Figure 2 As shown, it includes: S1. Install vibrating wire strain gauges at key cable locations around the perimeter of the air-supported membrane structure of the foundation pit to establish stress monitoring points; S2. Automatically collect cable stress data at each stress monitoring point at preset time intervals and transmit it to the intelligent analysis platform; S3. Calculate the stress change in adjacent time periods and compare it with the preset threshold in real time; S4. When the stress change exceeds a preset threshold, an early warning push is automatically triggered, and an early warning message is sent to a preset terminal; The preset threshold is determined based on the cable material properties and structural safety level, and the stress change is calculated as the difference between the stress value at the current moment and the stress value at the previous moment.

[0068] Furthermore, according to one embodiment of the present invention, it further includes: S5. Simultaneously monitor wind speed and snow thickness, establish a correlation analysis between stress change and environmental load parameters, and dynamically adjust the preset threshold and / or data acquisition frequency when the wind speed change exceeds the preset wind speed threshold and / or the snow thickness change exceeds the preset snow thickness threshold.

[0069] Furthermore, according to one embodiment of the present invention, the preset threshold in step S3 is 50 MPa, and an early warning is triggered when the stress change exceeds 50 MPa.

[0070] Furthermore, according to one embodiment of the present invention, the dynamic adjustment in step S5 includes: When the wind speed change exceeds 2 m / s and / or the snow thickness change exceeds 0.01 m, the preset threshold will be reduced to 70%~80% of the original preset threshold, and / or the data acquisition frequency will be increased to twice the original frequency.

[0071] Furthermore, according to one embodiment of the present invention, step S6 is also included: Based on historical monitoring data and numerical simulation results, a stress prediction model is established to predict the stress development trend of the air-supported membrane structure under future loads. When the predicted stress value for a future period exceeds the allowable stress or safety factor limit of the cable material, an early warning is issued to achieve risk prevention and control.

[0072] According to the above-described scheme of this invention, this invention addresses three major technical defects of existing foundation pit air-supported membrane structure monitoring technologies: structural deviation of the monitored object, passive and lagging early warning mechanism, and disconnect between monitoring sensitivity and environmental load. It provides an intelligent monitoring system and method for the safety of foundation pit air-supported membrane structures. This invention establishes a wind / snow load response evaluation system based on cable stress. It collects key cable stress data in real time using vibrating wire strain gauges, using stress change (stress difference between adjacent time periods) as the core monitoring indicator. This shifts the monitoring focus from static absolute stress values ​​to dynamic stress change rates, thereby capturing the critical process of structural response. Simultaneously, it establishes a correlation mapping relationship between stress change and wind speed and snow thickness. When environmental load changes abruptly, it automatically increases the data acquisition frequency and lowers the early warning threshold, achieving adaptive matching between monitoring sensitivity and environmental load. Furthermore, by combining time-history analysis of historical stress data with numerical simulation, it predicts future stress development trends and issues early warnings when the predicted stress value exceeds the material's allowable stress or safety factor limit.

[0073] This invention overcomes the limitations of traditional methods that primarily rely on membrane pressure monitoring, achieving real-time characterization of the overall structural stability through cable stress monitoring. It overcomes the passivity of fixed threshold and fixed frequency monitoring, enabling dynamic adjustment of monitoring strategies and early risk control. It solves the technical obstacle of directly transplanting vibrating wire strain gauges to air-supported membrane cable monitoring, ensuring the representativeness and reliability of monitoring through anchorage placement and waterproof sealing design. Ultimately, it significantly improves the monitoring reliability and early warning timeliness of air-supported membrane structures in foundation pits during cross-seasonal construction, especially under extreme weather conditions, providing valuable emergency response time for on-site personnel and promoting the safe application and large-scale promotion of foundation pit air-supported membrane technology.

[0074] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this application.

[0075] It should be understood that the sequence number of each step in the invention and its embodiments does not absolutely imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Claims

1. A safety monitoring system for an air-supported membrane structure in a foundation pit, characterized in that, include: Vibrating wire strain gauges are installed at key cable locations around the periphery of the air-supported membrane structure in the foundation pit to collect cable stress data in real time. The data acquisition module is communicatively connected to the vibrating wire strain gauge and is used to automatically acquire stress data at preset time intervals. The intelligent analysis platform is connected to the data acquisition module to receive stress data and calculate the stress change in adjacent time periods, and compares the stress change with a preset threshold. The early warning push module is connected to the intelligent analysis platform and automatically pushes early warning information to a preset terminal when the stress change exceeds a preset threshold. The preset threshold is determined based on the cable material properties and structural safety level, and the stress change is calculated as the difference between the stress value at the current moment and the stress value at the previous moment.

2. The safety monitoring system for foundation pit air-supported membrane structures according to claim 1, characterized in that, The vibrating wire strain gauge is deployed on the key load-bearing cables of the inclined mesh anchoring system around the air-supported membrane structure. The cables are connected to the air-supported membrane material via cable clamps, and the vibrating wire strain gauge is fixed to the anchoring end of the cable via a waterproof sealing kit.

3. The safety monitoring system for foundation pit air-supported membrane structures according to claim 1, characterized in that, The intelligent analysis platform establishes a correlation mapping relationship between stress change and wind speed and snow thickness. When the detected wind speed change exceeds a preset wind speed threshold and / or the snow thickness change exceeds a preset snow thickness threshold, the intelligent analysis platform automatically increases the data acquisition frequency and / or decreases the preset threshold.

4. The safety monitoring system for foundation pit air-supported membrane structures according to claim 3, characterized in that, The preset wind speed threshold is 2 m / s, and the preset snow accumulation threshold is 0.01 m. The automatic increase in data acquisition frequency is to increase it to twice the original data acquisition frequency, and the reduction of the preset threshold is to reduce it to 70%~80% of the original preset threshold.

5. The safety monitoring system for foundation pit air-supported membrane structures according to claim 1, characterized in that, The early warning push module pushes early warning information to preset terminals through a wireless communication network. The early warning information includes: abnormal stress changes, corresponding wind speed / snow load data, suggested handling measures, and current safety status assessment of the air-supported membrane structure.

6. The safety monitoring system for foundation pit air-supported membrane structures according to claim 1, characterized in that, The intelligent analysis platform stores historical stress data and constructs stress time history curves; Based on the stress time history curve and numerical simulation results, the intelligent analysis platform predicts the stress development trend of the air-supported membrane structure under future loads. When the predicted stress value exceeds the allowable stress of the cable material or the preset safety factor limit, the intelligent analysis platform generates a prediction warning and pushes it to a preset terminal through the warning push module.

7. A method for safety monitoring of an air-supported membrane structure in a foundation pit, characterized in that, include: S1. Install vibrating wire strain gauges at key cable locations around the perimeter of the air-supported membrane structure of the foundation pit to establish stress monitoring points; S2. Automatically collect cable stress data at each stress monitoring point at preset time intervals and transmit it to the intelligent analysis platform; S3. Calculate the stress change in adjacent time periods and compare it with the preset threshold in real time; S4. When the stress change exceeds a preset threshold, an early warning push is automatically triggered, and an early warning message is sent to a preset terminal; The preset threshold is determined based on the cable material properties and structural safety level, and the stress change is calculated as the difference between the stress value at the current moment and the stress value at the previous moment.

8. The method for safety monitoring of an air-supported membrane structure in a foundation pit according to claim 7, characterized in that, Also includes: S5. Simultaneously monitor wind speed and snow thickness, establish a correlation analysis between stress change and environmental load parameters, and dynamically adjust the preset threshold and / or data acquisition frequency when the wind speed change exceeds the preset wind speed threshold and / or the snow thickness change exceeds the preset snow thickness threshold.

9. The method for safety monitoring of an air-supported membrane structure in a foundation pit according to claim 7, characterized in that, The preset threshold in step S3 is 50 MPa. When the stress change exceeds 50 MPa, an early warning is triggered.

10. The method for safety monitoring of an air-supported membrane structure in a foundation pit according to claim 8, characterized in that, The dynamic adjustment in step S5 includes: When the wind speed change exceeds 2 m / s and / or the snow thickness change exceeds 0.01 m, the preset threshold will be reduced to 70%~80% of the original preset threshold, and / or the data acquisition frequency will be increased to twice the original frequency.

11. The method for safety monitoring of an air-supported membrane structure in a foundation pit according to claim 7, characterized in that, Also includes: S6. Based on historical monitoring data and numerical simulation results, establish a stress prediction model; When the predicted stress value for a future period exceeds the allowable stress or safety factor limit of the cable material, an early warning is issued to achieve risk prevention and control.

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