Intelligent monitoring system for deformation and stress of deep foundation pit support structure

Abstract

The present invention discloses an intelligent monitoring system for deformation and stress of a deep foundation pit support structure, relates to the technical field of deep foundation pit support monitoring, and is used to solve the problem of poor early warning of deformation risks of support structures. The present invention realizes high-density collection of inclination angles, deformations and stress data of key areas of the deep foundation pit support structure by constructing a sensitivity-driven measuring point layout mechanism. An inversion model is constructed based on stress and strain rate to obtain the structural equivalent modulus and extract its change rate, judge the stiffness evolution trend, and further construct a modulus change rate spatial field. The regional threshold is set in combination with the disturbance sensitivity factor to realize abnormal area identification and spatial positioning, and on this basis, structural response behavior information is extracted. According to the analysis results of the structural response behavior information, the system is driven to trigger a hierarchical response strategy to realize intelligent early warning of local deformation and stress instability of the deep foundation pit support structure.

Description

Technical Field

[0001] The present invention relates to the technical field of deep foundation pit support monitoring, and more particularly to an intelligent monitoring system for deformation and stress of a double-row pile plus front-support steel pipe deep foundation pit support structure. Background Art

[0002] Deep foundation pit support structures are an indispensable safety protection system for major projects such as urban underground space development, subway construction, and high-rise building foundation engineering. The scale, depth, and construction complexity of deep foundation pit projects have also increased significantly, and support structures often face multiple challenges, including higher loads, complex geological conditions, and interference from adjacent buildings. Double-row piles with front-supported steel pipes are a highly efficient composite support structure commonly used in deep foundation pit projects. They are suitable for complex foundation pit environments with loose soil, abundant groundwater, or densely populated adjacent buildings. This structure consists of two parallel rows of reinforced concrete piles (front and rear rows) forming the main support system. These piles share lateral earth pressure through the intervening soil, creating a soil-pile synergy. The front row of piles typically directly bears the primary load on the excavation's open side, while the rear row of piles provides auxiliary support by strengthening overall stiffness and controlling deformation.

[0003] Deficiencies in existing technologies: Deep foundation pit support structure monitoring often focuses on the absolute value judgment of stress or deformation, while ignoring the dynamic coupling relationship between stress and strain, resulting in the inability to accurately identify sudden changes in structural stiffness, nonlinear response, or response lag. In addition, existing monitoring systems usually rely on fixed thresholds for early warning and lack trend analysis of the structural state evolution process. Especially in the early stages of local damage, it is often difficult to detect in time, causing the identification of dangerous areas in deep foundation pit support to lag behind the development of actual risks, thereby adversely affecting the project. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the following solution is proposed to solve the problem of poor early warning of deformation risk of the support structure in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The deep foundation pit support structure deformation and stress intelligent monitoring system includes a support data acquisition module, a structural stiffness trend analysis module, an abnormal area identification module, and a grading strategy adjustment module. Each module is connected by signals.

[0007] The support data acquisition module is used to collect deformation and stress monitoring data of deep foundation pit support structures, identify high-density deployment areas, and deploy and collect inclination angle data in high-density deployment areas;

[0008] The structural stiffness trend analysis module is used to establish an inverse relationship based on the real-time stress change rate and strain rate of the structure, obtain the current equivalent modulus of the structure, extract the equivalent modulus change sequence to determine the equivalent modulus change rate, and judge the structural stiffness evolution trend;

[0009] The abnormal area identification module is used to construct the modulus change rate field based on the equivalent modulus change rate, and set the partition threshold in combination with the disturbance sensitivity factor to identify and spatially locate the structural abnormal area;

[0010] The hierarchical strategy adjustment module is used to obtain and analyze the structural behavior information generated by the abnormal area after spatial positioning of the abnormal area, and trigger the hierarchical response strategy according to the structural behavior analysis results.

[0011] In a preferred embodiment, for collecting deformation and stress monitoring data of deep foundation pit support structures, determining key measurement areas, and deploying collection of inclination angle data in the key measurement areas, the specific steps are as follows:

[0012] Based on the theoretical principal stress ratio of the support structure, the response intensity of disturbance or unloading, and the importance coefficient of the impact of local instability or damage on the overall structural safety, the layout density distribution function is used to determine the key measurement area;

[0013] In key measurement areas, fiber Bragg grating strain sensors and laser displacement sensors are used to collect structural deformation data in real time, and Brillouin fiber stress sensors are used to collect data. The stress is inverted by measuring frequency changes to obtain stress data, and MEMS inclinometers are deployed for real-time monitoring to obtain the tilt angle data of the structural nodes.

[0014] In a preferred embodiment, the method for establishing an inversion relationship between the real-time stress change rate and the strain rate of the structure to obtain the current equivalent modulus of the structure includes the following specific steps:

[0015] Perform first-order difference calculation based on strain data and stress data to obtain the structural strain rate and stress change rate;

[0016] The equivalent modulus is determined based on the local approximate linear transient response relationship between the structural strain rate and the stress change rate in a continuous time series.

[0017] In a preferred embodiment, the equivalent modulus change sequence is extracted to determine the equivalent modulus change rate and to determine the structural stiffness evolution trend. The specific steps are as follows:

[0018] Determine the support structure according to the variation of equivalent modulus;

[0019] If the equivalent modulus variation is stable, the support structure is in the normal elastic response stage;

[0020] If the equivalent modulus drops rapidly, the support structure is in a nonlinear, degenerate or unstable stage;

[0021] Obtain the equivalent modulus sequence obtained by inversion processing, and use the first-order derivative of the equivalent modulus with time as the equivalent modulus change rate;

[0022] The structural stiffness evolution trend is determined based on the rate of change of the equivalent modulus.

[0023] In a preferred embodiment, determining the structural stiffness evolution trend according to the equivalent modulus change rate comprises the following steps:

[0024] If the rate of change of the equivalent modulus is less than 0, it means that the stiffness of the deep foundation pit support structure is in a weakening trend;

[0025] If the absolute value of the equivalent modulus change rate increases, it indicates that the stiffness evolution of the deep foundation pit support structure is discontinuous, and it is easy to have a sudden change in the structural state or an external interference event;

[0026] If the rate of change of the equivalent modulus remains unchanged, it means that the structural stiffness maintains a stable trend and is in the safety response stage.

[0027] In a preferred embodiment, the modulus change rate field is constructed based on the equivalent modulus change rate, and the partition threshold is set in combination with the disturbance sensitivity factor to identify and spatially locate the structural abnormality area. The specific steps are as follows:

[0028] The monitoring position of the deep foundation pit support structure and the rate of change of the equivalent modulus are combined into a set of measuring points;

[0029] Using local structure related interpolation to check the set of measuring points, spatial interpolation is performed to determine the modulus change rate values ​​of different monitoring points, and the modulus change rate spatial field is constructed according to the modulus change rate values;

[0030] A regional modulus change rate judgment threshold is set and compared with the modulus change rate value to determine whether there is any abnormal change in the current state of the support structure.

[0031] In a preferred embodiment, a regional modulus change rate determination threshold is set and compared with the modulus change rate value to determine whether there is an abnormal change in the current state of the support structure. The specific steps are as follows:

[0032] If the modulus change rate value exceeds the modulus change rate judgment threshold, it means that there is a risk of abnormal structural performance in the detection area and it is marked as an abnormal area;

[0033] After judging all monitoring points, a structural stiffness anomaly distribution map is generated, and the identified abnormal areas are marked to form a spatial anomaly mask layer or risk heat map.

[0034] In a preferred embodiment, after spatially locating the structural abnormality region, the structural behavior information generated by the abnormal region is obtained and analyzed. The specific steps are as follows:

[0035] After obtaining the spatial location of the abnormal area of ​​structural modulus change, the structural behavior information generated by the abnormal area process is obtained;

[0036] Structural behavior information includes structural response distortion index and structural response hysteresis index;

[0037] The structural response distortion index indicates the degree of deviation between the actual stress response of the structure and the design theoretical response;

[0038] The structural response hysteresis index indicates the time delay of the structure's stress-strain response relative to the strain input;

[0039] The structural response distortion threshold and structural response hysteresis threshold are compared and analyzed with the structural response distortion index and structural response hysteresis index respectively.

[0040] In a preferred embodiment, a hierarchical response strategy is triggered according to the structural behavior analysis results, and the specific steps are as follows:

[0041] When the structural response distortion index is less than the structural response distortion threshold and the structural response hysteresis index is less than the structural response hysteresis threshold, the support structure does not need to be adjusted and monitoring continues;

[0042] When the structural response distortion index is greater than or equal to the structural response distortion threshold and the structural response hysteresis index is less than the structural response hysteresis threshold, the entire structure is still in a fluctuating state, and the frequency of change trends in the monitoring support structure area is increased;

[0043] When the structural response distortion index is less than the structural response distortion threshold and the structural response hysteresis index is greater than or equal to the structural response hysteresis threshold, the data collection frequency is increased and long-term monitoring is carried out;

[0044] When the structural response distortion index is greater than or equal to the structural response distortion threshold and the structural response hysteresis index is greater than or equal to the structural response hysteresis threshold, it is necessary to immediately trigger an early warning and take enhanced detection or emergency assessment measures.

[0045] The technical effects and advantages of the intelligent monitoring system for deformation and stress of deep foundation pit support structures of the present invention are as follows:

[0046] The present invention realizes the precise collection of inclination angle, deformation and stress data of key areas of deep foundation pit support structure by constructing a high-density measurement point layout mechanism based on sensitivity distribution analysis; establishes a dynamic inversion model based on stress change rate and strain rate, obtains the structural equivalent modulus in real time and extracts its change sequence to judge the evolution trend of structural stiffness; further constructs the modulus change rate spatial field, integrates the disturbance sensitivity factor to set the regional judgment threshold, and realizes the precise identification and spatial positioning of abnormal areas; based on the identified abnormal modulus change area, extracts the structural response behavior information, calculates the structural response distortion and hysteresis characteristics, evaluates the local nonlinearity and hysteresis energy consumption behavior, and finally drives the structural intelligent monitoring system to trigger the response classification strategy, thereby improving the timeliness and accuracy of risk identification of deep foundation pit support structure, thereby realizing early warning and dynamic control of the local instability trend of deep foundation pit support structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a structural schematic diagram of the intelligent monitoring system for deformation and stress of deep foundation pit support structure of the present invention. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] In order to achieve the above objectives, Figure 1 The structural diagram of the intelligent monitoring system for deformation and stress of deep foundation pit support structure of the present invention is given. Specifically, it includes a support data acquisition module, a structural stiffness trend analysis module, an abnormal area identification module and a hierarchical strategy adjustment module. The modules are connected by signals.

[0050] The support data acquisition module is used to collect deformation and stress monitoring data of deep foundation pit support structures, identify high-density deployment areas, and deploy and collect inclination angle data in high-density deployment areas;

[0051] The structural stiffness trend analysis module is used to establish an inverse relationship based on the real-time stress change rate and strain rate of the structure, obtain the current equivalent modulus of the structure, extract the equivalent modulus change sequence to determine the equivalent modulus change rate, and judge the structural stiffness evolution trend;

[0052] The abnormal area identification module is used to construct the modulus change rate field based on the equivalent modulus change rate, and set the partition threshold in combination with the disturbance sensitivity factor to identify and spatially locate the structural abnormal area;

[0053] The hierarchical strategy adjustment module is used to obtain and analyze the structural behavior information generated by the abnormal area after spatial positioning of the abnormal area, and trigger the hierarchical response strategy according to the structural behavior analysis results.

[0054] Step 1: Collect deformation and stress monitoring data of the double-row pile plus front-support steel pipe deep foundation pit support structure, obtain real-time deformation and stress data of the support structure, and construct the deformation field and stress field of the support structure. The specific steps are as follows:

[0055] The support structure is affected by the soil and the construction process. There are obvious spatial differences between stress concentration areas and deformation-sensitive areas. Based on the distribution law of stress and deformation of the support structure theory and the results of finite element analysis, the high sensitivity of different areas within the support structure is determined as the key measurement area of ​​the support structure.

[0056] Based on theoretical analysis and finite element simulation, the spatial sensitive distribution of stress and strain is predicted. The specific process is as follows:

[0057] Structural force theory divides stress and strain-dominant regions based on the support structure type (such as pile rows, underground continuous walls, support beams, and water-stop curtains) and construction phase (excavation, support installation, backfill, etc.). First, a force path analysis of the structural system is conducted to determine the stress and strain concentration areas of each component under typical working conditions. In theory, stress concentration is prone to occur at locations such as the bottom corners, pile tops, and transitions of the structure, while the strain response of locations such as the transition zone and boundary zone is sensitive. By analyzing these key structural features at the structural mechanics level, a preliminary sensitive zoning framework is obtained.

[0058] Finite element simulation analysis is to construct a two-dimensional or three-dimensional finite element analysis model based on the on-site geological parameters, structural design parameters and excavation construction stage, set typical load conditions (such as lateral earth pressure, self-weight, support reaction force, etc.), and use linear or nonlinear constitutive models for simulation calculations to obtain the principal stress distribution field and principal strain distribution field of different areas of the structure at each stage;

[0059] According to theoretical analysis and finite element simulation, the measurement point layout density distribution function is established as follows: ,in, It represents the theoretical principal stress ratio at the support structure position x, obtained by finite element simulation or code recommendation, and the value range is 0 to 1; It represents the response intensity of position x to disturbance or unloading, which is usually calculated based on the structural stiffness and load distribution characteristics; The importance coefficient of the impact of local instability or damage on the overall structural safety is obtained through empirical formulas or expert evaluation. For example, higher values ​​are given to key nodes such as corners, intersections, and columns. f represents the operation function.

[0060] A specific example is as follows: The measurement point layout density distribution function is: , , , The layout strategy weight coefficient of each parameter is used to adjust the influence of different factors in the layout decision to meet the normalization condition ;

[0061] Assume that , used to emphasize stress concentration areas; , used to take into account geological heterogeneity; , to ensure that the key points of the structure are covered, and the bottom corners of the structure are simulated; respectively 、 、 are 0.9, 0.6, and 1.0, and the value calculated by substituting them into the density distribution function of the measurement point layout is 0.83;

[0062] This indicates that the point measurement density value is 0.83, which belongs to a high-density deployment area, that is, a key measurement area. High-precision multi-source sensors should be deployed preferentially in key measurement areas.

[0063] Accurately measure and calculate deformation data. The support structure may undergo displacement and strain during construction and use. Therefore, it is necessary to collect structural deformation data in real time to reflect the dynamic behavior of the structure. High-precision fiber Bragg grating strain sensors (FBGs) and laser displacement sensors are used to measure the following:

[0064] Fiber Bragg gratings (FBGs) generate strain when their structure deforms, which manifests as a change in the reflection center wavelength. The wavelength change is obtained through precise demodulation measurement, and the structural strain is then calculated: , where The wavelength change measured by the sensor in real time; is the strain calibration coefficient, calibrated in the laboratory; is the initial wavelength of the fiber Bragg grating;

[0065] Laser sensors use the principle of triangulation to accurately measure the surface displacement of structures and reflect the displacement changes of the entire or local structure in real time: ,in, It is the initial calibration distance determined during installation; is the actual measured real-time distance;

[0066] The two types of sensors cooperate with each other to provide multi-scale and multi-precision deformation information and form a deformation data set.

[0067] Real-time measurement and calculation of structural stress data. Changes in internal stress of a structure are an important basis for judging structural stability. Therefore, it is necessary to simultaneously monitor the internal stress of key areas of the structure. Brillouin fiber optic stress sensors are used for real-time measurement. Stress is calculated by measuring frequency changes to obtain stress data.

[0068] Changes in the overall inclination of the support structure can indirectly reflect the stress state and potential instability of the structure. Therefore, MEMS inclinometers are deployed at key nodes for real-time monitoring to calculate the inclination angle of the structural nodes.

[0069] The tilt angle data is used together with the deformation and stress data to jointly evaluate the overall status of the support structure.

[0070] Perform high-precision time synchronization and data adaptive compensation calibration on the collected sensor data.

[0071] Step 2: Perform a joint inversion of deformation rate and stress change. Based on the inherent physical relationship between stress and deformation data, analyze the dynamic evolution of the actual bearing characteristics and safety performance of the support structure. The specific steps are as follows:

[0072] Establish a joint inversion relationship between stress and strain rate. In the safety status assessment of deep foundation pit support structures, the actual stiffness of the structure is an important evaluation indicator. The actual stiffness of the structure on site cannot be directly measured. Therefore, an indirect inversion technique is used. Based on the real-time stress change rate and strain rate data of the structure and the principles of elastic mechanics, the current equivalent stiffness parameters of the structure are dynamically derived, thereby reflecting the actual bearing capacity and deformation characteristics of the structure.

[0073] Extract effective information on the rate of structural change, perform first-order difference calculations on strain and stress data, and obtain the structural strain rate and stress change rate ;

[0074] For any time t in the continuous time series, it is assumed that the instantaneous response relationship of the support structure at that time is locally approximately linear, that is, the response of the stress change to the current strain rate approximately satisfies the following relationship: ,in, is the equivalent modulus of the support structure at the tth moment;

[0075] Rewrite this as an expression for the equivalent modulus: , where It is a very small positive value to avoid numerical instability when the denominator approaches zero;

[0076] Real-time state quantity of structural stiffness (i.e. equivalent modulus ) reflects the current load-bearing capacity of the structure, while the continuous time variation trend of this quantity reveals the evolution of the structural stiffness. If the support structure is in the normal elastic response stage, the change amplitude of its equivalent modulus should be relatively stable; if the equivalent modulus shows a rapid decline or short-term violent fluctuations, it usually indicates that the structure has entered a nonlinear, degenerate, or unstable stage.

[0077] Get the equivalent modulus sequence obtained by dynamic inversion: , the modulus sequence corresponds to the discrete time points ,in , is the data sampling period, ensuring uniform alignment of the time axis;

[0078] The rate of change of the equivalent modulus is defined as The first-order derivative with respect to time is expressed in discrete form as follows: ,in, Indicates at time The modulus evolution rate on , that is, the change in structural stiffness per unit time;

[0079] like , it means that the stiffness of the deep foundation pit support structure is in a weakening trend, which may be due to cracks in the support components, loosening of the structure caused by soil unloading, etc.

[0080] like If it increases suddenly, it means that the stiffness evolution of the deep foundation pit support structure is discontinuous, and attention should be paid to whether a sudden change in the structural state or an external interference event has occurred;

[0081] like , it means that the structural stiffness maintains a stable trend and is in the safety response stage.

[0082] By obtaining sensitive data on the trend of structural stiffness changes, local degradation of the structure can be captured in advance.

[0083] In deep foundation pit projects, safety risks of support structures often first appear in local areas, such as corners, connection nodes, and backfill boundaries. Due to the local superposition of factors such as construction disturbance, geological unevenness, and soil unloading, the structural stiffness is prone to sudden or continuous decreases.

[0084] By analyzing the modulus change rate, we have obtained the stiffness change trend of each measuring point on the time axis. We have established a spatial recognition mechanism for abnormal modulus changes to identify areas with sudden stiffness drops, hot spots of change trends, and abnormal propagation paths, and to perform spatial risk location and zoning warnings. The specific steps are as follows:

[0085] The modulus change rate value G(x, y, t) is defined in the two-dimensional space domain and is constructed by taking the set of measuring points as For spatial interpolation, the local structure-related interpolation kernel is constructed as follows: ,in, is the modulus change rate of the i-th measuring point; is the local weighted kernel function; is the weight adjustment coefficient related to the local structure type of the measuring point (for example, the weight of the connection area, pile top, etc. can be amplified); is the i-th monitoring position of the deep foundation pit support structure, Represents the Euclidean space distance operation;

[0086] The output modulus change rate value is a continuous space-time modulus change rate function, which can be used to construct stiffness anomaly heat map, joint regional threshold model for anomaly judgment, etc.

[0087] By spatially interpolating the dynamic modulus change rate at discrete measuring points, a continuous function field is constructed. The constructed modulus change rate spatial field is used to determine the stiffness evolution trend of the deep foundation pit support structure at different times and spatial positions. This spatial field can identify local stiffness drop areas and abnormal stiffness fluctuation propagation paths.

[0088] By analyzing the heterogeneity of structural topology and geological conditions, the spatial function provides an embedded extension of the physical structure of traditional RBF or spline interpolation, which can more realistically restore the physical propagation characteristics of abnormal trends.

[0089] In the safety monitoring of supporting structures, using only the modulus change rate itself to make a unified global abnormality judgment may ignore the differences in design rationality and safety tolerance in different regions. For example, the support bottom corner area may allow a large range of modulus fluctuations due to structural stress redistribution and uneven foundation, while the structural corners or areas near high-risk construction units are extremely sensitive to stiffness changes, and even small changes may cause structural imbalance. Therefore, a modulus change rate threshold with regional differentiation discrimination capability is constructed to determine abnormal areas. The specific process is as follows:

[0090] The regional modulus change rate threshold is defined as: ,in, is the structural benchmark tolerance coefficient, which is a global adjustment parameter and reflects the average acceptance range of the overall structural design to modulus fluctuations; The theoretical modulus field provided for structural design drawings or finite element models is used to define the stiffness baseline at each point. For example, it may be set to 30 GPa at the top of a pile and 20 GPa in the middle of a wall, reflecting the design model's quantitative expectations of the performance of different structural elements. is the disturbance sensitivity factor, and its value range is [0, 1];

[0091] The constructed regional modulus change rate determination threshold reflects the maximum modulus change rate allowed at that location. Its design logic is to allow a relatively larger fluctuation range in areas with a high stiffness benchmark (such as structural piles and end trusses), and to lower the overall threshold in disturbance-sensitive or structurally critical areas, making monitoring more stringent. In addition, the regional modulus change rate determination threshold is not a constant, but varies with spatial position, reflecting the actual needs of structural design and engineering environment.

[0092] After completing the construction of the modulus change rate spatial field (i.e., clarifying the speed of stiffness change in each area of ​​the structure at a certain moment) and the establishment of the regional modulus change judgment threshold field (i.e., the maximum allowable change rate at each spatial position), a logical judgment relationship is established between the two to identify whether there is any abnormal change in the current state of the support structure. The specific steps are as follows:

[0093] Compare the modulus change rate value with the modulus change judgment threshold point by point. That is, for each spatial position within the structural monitoring area, the system will automatically compare the modulus change rate value of the position at the current moment with the modulus change rate judgment threshold corresponding to the position. If the modulus change rate value exceeds the modulus change rate judgment threshold, it means that the stiffness change in the area has exceeded the acceptable range, indicating that there is a risk of abnormal structural performance at the location, and the location is marked as an abnormal area;

[0094] After performing the above judgment on all monitoring points, the system generates a structural stiffness anomaly distribution map. On this map, areas identified as abnormal will be marked, forming a spatial anomaly mask layer or risk heat map, showing areas where local structural stiffness declines or fluctuates sharply.

[0095] In addition, the identification results of abnormal areas will also serve as one of the feedback conditions of the intelligent monitoring system to adjust the subsequent data sampling strategy. The system will prioritize increasing the monitoring frequency of these areas, activate redundant sensor nodes, and form a spatially adaptive data collection mechanism, thereby achieving efficient resource allocation and dynamic risk focusing.

[0096] It should be noted that the structural benchmark tolerance coefficient is usually set according to the stiffness reduction index in the underground engineering structure design code, and the recommended value range is 0.02 to 0.10; the disturbance sensitivity factor can be constructed by comprehensively considering the following information: geological disturbance level (such as 0.8 for weak clay areas and 0.2 for bedrock areas), density of surrounding construction activities (such as high values ​​for areas close to temporary buildings and traffic load sources), structural node characteristics (such as artificially amplifying the sensitivity of key structural unit nodes), historical support stability records (evaluating the fluctuation intensity based on the trend of the historical rate standard deviation curve), and the final disturbance sensitivity factor can be obtained by normalized superposition.

[0097] Step 3: Identify structural response distortion. This involves analyzing the difference between the actual structural response (stress-strain relationship) and the ideal theoretical response of the structure to identify areas of abnormal structural response. The specific steps are as follows:

[0098] After completing the identification of the stiffness change rate and spatial abnormal area, further analysis is conducted to determine whether the local response of the structure has abnormal stress-deformation behavior patterns. After obtaining the spatial location of the abnormal area of ​​structural modulus change, the structural behavior information generated by the abnormal area process is obtained. The structural behavior information includes the structural response distortion index and the structural response hysteresis index.

[0099] The structural response distortion index is an indicator used to quantify the degree of deviation between the actual stress response of a structure and the design theoretical response. The structural response distortion index measures whether the structure exhibits nonlinear distortion behavior in the stress-strain rate response relationship at a certain moment. Under ideal conditions, the stress change of the support structure should show a stable and linear correspondence with the strain rate, and the ratio is close to the elastic modulus set in the structural design stage. However, during the construction or operation of deep foundation pits, the actual response of the structure may gradually deviate from this ideal relationship due to factors such as crack initiation, node loosening, component yielding or sudden load changes, showing abnormal phenomena such as sudden drop in stiffness, drastic response fluctuations or uneven deformation. The structural response distortion index was proposed in this context. It comprehensively measures this deviation by simultaneously considering multiple physical dimensions such as the deviation of the stress-strain rate ratio, strain acceleration and dynamic stiffness fluctuations.

[0100] The main measurement object of the structural response distortion index is the response consistency between the structural stiffness and deformation. The larger the value, the more significant the deviation of the current stress behavior of the structure from its theoretical design, and it may be experiencing a nonlinear response or damage development stage. The structural response distortion index can not only be used to identify local problems such as stiffness mutation, nonlinear yielding, and shear relaxation, but also to capture small but continuous stiffness disturbance trends at an early stage. The introduction of the structural response distortion index enables the monitoring system to identify potential risks based on response behavior patterns rather than simple numerical anomalies, thereby playing a key role in the intelligent early warning of deep foundation pit support structures, and is used for the active identification of scenarios where structural performance continuously evolves and local instability precursors are predicted;

[0101] The steps to obtain the structural response distortion index are as follows:

[0102] Obtain the historical stress series and strain time series read by the stress sensor in the abnormal area, and obtain the current time point t and the next moment The stress values ​​are 、 , calculate the stress change rate: ;

[0103] Get the current time point t and the next moment The strain values ​​are 、 , calculate the strain rate: , the strain acceleration is obtained as: ;

[0104] The abnormal equivalent modulus is calculated based on the strain rate and stress change rate at the current time point t. The calculation expression is: , calculate the abnormal modulus fluctuation value of the two adjacent moments before and after the current moment: , obtain the theoretical modulus of the abnormal area , calculate the structural response distortion index, the calculation expression is: .

[0105] It should be noted that the theoretical modulus of the abnormal area is obtained from the deep foundation pit support structure design drawings, specifications and standards or finite element models. If it is a spatially distributed modulus, a corresponding modulus value can be set at each measuring point. During the implementation process, it can be used as a static input item and compared with the dynamic monitoring results.

[0106] The structural response hysteresis index is a time-series indicator used to quantify whether a structure exhibits significant hysteresis and energy dissipation characteristics during its stress-strain response. It measures whether the structure's stress response relative to the strain input exhibits time delay, path inconsistency, or inelastic hysteresis within a specific time window. Under ideal elastic conditions, structural stress should respond synchronously with strain, and loading and unloading paths should be completely consistent. However, in actual deep foundation pit support structures, factors such as soil disturbance, contact nonlinearity, structure-soil interaction, and local slip can cause the stress response to lag behind the strain, or generate hysteresis loops, manifesting as energy loss and stiffness degradation.

[0107] The structural response hysteresis index integrates the deviation of the stress response from the linear relationship within the historical time window and combines the deviation between the actual stress work per unit volume and the theoretical elastic work to comprehensively reflect the degree of structural hysteresis and energy dissipation. This index measures the dynamic consistency and dissipation capacity of the structural response process. The larger the value, the more likely the structure deviates from the linear relationship and may be experiencing significant hysteresis response, shear slip, yield energy dissipation, or contact loosening.

[0108] The role of the structural response hysteresis index is to reveal historical degradation behaviors that are difficult to identify through instantaneous stiffness indicators. It is particularly suitable for analyzing the performance evolution trend of structures under long-term loads or multiple disturbance conditions. It enables the monitoring system to identify hidden risk states where the structure appears stable but is actually hysteretic, providing key support for accurate early warning and early identification of delayed damage.

[0109] The logic for obtaining the structural response hysteresis index is as follows:

[0110] Get the abnormal area in Stress change rate at time and strain rate , construct a sliding time window with a local length of 2n+1, and use the least squares method to calculate the fitting slope between the stress change rate and the strain rate as the local elastic modulus. The calculation formula is: , where n represents the half-width of the fitting window;

[0111] In the lag analysis time window The actual stress work in the time window is calculated using the trapezoidal method to obtain the stress work: Similarly, the theoretical stress input work within the time window is calculated to obtain the calculated elastic work: ,in, is the time window width of the hysteresis analysis; the structural response hysteresis index is calculated as: .

[0112] It should be noted that the stress change rate and strain rate of the structural response hysteresis index are obtained in the same way as the stress change rate and strain rate of the structural response distortion index; n represents the half width of the fitting window, that is, Take n sampling points forward and backward as the center, and a total of 2n+1 points are used for least squares fitting; the total number of sampling moments included in the time window is set according to actual sampling requirements.

[0113] The structural response distortion threshold is set to determine whether there is an abnormal deviation in the stiffness response at any time at the monitoring location. The structural response hysteresis threshold is used to determine whether the structure has obvious hysteresis behavior or energy dissipation process over a period of time. These thresholds are compared and analyzed with the structural response distortion index and structural response hysteresis index respectively.

[0114] When the structural response distortion index is less than the structural response distortion threshold and the structural response hysteresis index is less than the structural response hysteresis threshold, it means that the real-time stress-strain rate ratio of the structure is close to its design modulus, indicating that the structure does not experience a sudden change in stiffness or nonlinear response. Therefore, the structural response distortion index is within the normal range. At the same time, the structure exhibits good response synchronization within the hysteresis analysis time window, and the deviation between the historical stress work and the theoretical elastic work is small.

[0115] When the structural response distortion index is greater than or equal to the structural response distortion threshold and the structural response hysteresis index is less than the structural response hysteresis threshold, it means that the stress response of the structure at the current moment has significantly deviated from the theoretical design modulus, and there are phenomena such as local stiffness drop, microcrack development, or response path mutation. Therefore, the structural response distortion index has exceeded the normal range. However, since the structural response hysteresis index is still lower than the hysteresis threshold, it means that the deviation behavior has not yet formed an obvious energy dissipation process or hysteresis accumulation. The overall structure is still in a short-term fluctuation state. Increase the frequency of monitoring the change trend in this area.

[0116] When the structural response distortion index is less than the structural response distortion threshold and the structural response hysteresis index is greater than or equal to the structural response hysteresis threshold, it means that the current stiffness of the structure is still maintained near the design modulus and no instantaneous response deviation occurs. Therefore, the structural response distortion index is in a normal state. However, within the hysteresis analysis time window, the structure shows obvious energy dissipation behavior, and there is a persistent deviation between stress work and elastic work, indicating the existence of plastic slip, soil decoupling, or contact interface creep. This state indicates that although the structure has no immediate stiffness mutation, it may be in a slow damage accumulation process. In this case, the data collection frequency should be increased and it needs to be included in the key long-term monitoring.

[0117] When the structural response distortion index is greater than or equal to the structural response distortion threshold and the structural response hysteresis index is greater than or equal to the structural response hysteresis threshold, it means that the stress-strain response relationship of the structure has not only deviated from the design modulus, showing obvious stiffness mismatch and nonlinear characteristics, but also there is significant response energy consumption and path inconsistency within the hysteresis analysis time window, indicating that the structure is experiencing a dual abnormal state of sudden inelastic behavior and hysteresis accumulation. At this time, we should be highly vigilant that the structure may be in the state of local yield, contact failure or instability boundary, and it is necessary to immediately trigger an early warning and take enhanced detection or emergency assessment measures.

[0118] In summary, the present invention realizes the precise collection of inclination angle, deformation and stress data of key areas of deep foundation pit support structure by constructing a high-density measurement point layout mechanism based on sensitivity distribution analysis; establishes a dynamic inversion model based on stress change rate and strain rate, obtains the structural equivalent modulus in real time and extracts its change sequence to judge the evolution trend of structural stiffness; further constructs the modulus change rate spatial field, integrates the disturbance sensitivity factor to set the regional judgment threshold, and realizes the precise identification and spatial positioning of abnormal areas; based on the identified abnormal modulus change area, extracts the structural response behavior information, calculates the structural response distortion and hysteresis characteristics, evaluates the local nonlinearity and hysteresis energy consumption behavior, and finally drives the structural intelligent monitoring system to trigger the response classification strategy, thereby improving the timeliness and accuracy of risk identification of deep foundation pit support structure, thereby realizing early warning and dynamic control of the local instability trend of deep foundation pit support structure.

[0119] The above formulas are all dimensionless and numerical calculations. The formula is a formula that is closest to the actual situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0120] The above embodiments may be implemented in whole or in part through software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments may be implemented in whole or in part in the form of a computer program product.

[0121] Those skilled in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0122] In addition, each functional module in each embodiment of the present application may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0123] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

[0124] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. The intelligent monitoring system for deformation and stress of deep foundation pit support structure is characterized by: It includes support data acquisition module, structural stiffness trend analysis module, abnormal area identification module and grading strategy adjustment module, and each module is connected through signals; The support data acquisition module is used to collect deformation and stress monitoring data of deep foundation pit support structures, identify high-density deployment areas, and deploy and collect inclination angle data in high-density deployment areas; The structural stiffness trend analysis module is used to establish an inverse relationship based on the real-time stress change rate and strain rate of the structure, obtain the current equivalent modulus of the structure, extract the equivalent modulus change sequence to determine the equivalent modulus change rate, and judge the structural stiffness evolution trend; The abnormal area identification module is used to construct the modulus change rate field based on the equivalent modulus change rate, and set the partition threshold in combination with the disturbance sensitivity factor to identify and spatially locate the structural abnormal area; A hierarchical strategy adjustment module is used to obtain and analyze the structural behavior information generated by the abnormal area after spatially locating the abnormal area, and trigger a hierarchical response strategy based on the structural behavior analysis results; After spatially locating the structural abnormality area, it is used to obtain the structural behavior information generated by the abnormal area and analyze it. The specific steps are as follows: After obtaining the spatial location of the abnormal area of ​​structural modulus change, the structural behavior information generated by the abnormal area process is obtained; Structural behavior information includes structural response distortion index and structural response hysteresis index; The structural response distortion index indicates the degree of deviation between the actual stress response of the structure and the design theoretical response; The structural response hysteresis index indicates the time delay of the structure's stress-strain response relative to the strain input; The structural response distortion threshold and structural response hysteresis threshold are compared and analyzed with the structural response distortion index and structural response hysteresis index respectively.

2. The intelligent monitoring system for deformation and stress of deep foundation pit support structure according to claim 1 is characterized by: It is used to collect deformation and stress monitoring data of deep foundation pit support structures, determine key measurement areas, and deploy and collect inclination angle data in key measurement areas. The specific steps are as follows: Based on the theoretical principal stress ratio of the support structure, the response intensity of disturbance or unloading, and the importance coefficient of the impact of local instability or damage on the overall structural safety, the layout density distribution function is used to determine the key measurement area; In key measurement areas, fiber Bragg grating strain sensors and laser displacement sensors are used to collect structural deformation data in real time, and Brillouin fiber stress sensors are used to collect data. The stress is inverted by measuring frequency changes to obtain stress data, and MEMS inclinometers are deployed for real-time monitoring to obtain the tilt angle data of the structural nodes.

3. The intelligent monitoring system for deformation and stress of deep foundation pit support structure according to claim 2 is characterized by: It is used to establish an inversion relationship based on the real-time stress change rate and strain rate of the structure to obtain the current equivalent modulus of the structure. The specific steps include: Perform first-order difference calculation based on strain data and stress data to obtain the structural strain rate and stress change rate; The equivalent modulus is determined based on the local approximate linear transient response relationship between the structural strain rate and the stress change rate in a continuous time series.

4. The intelligent monitoring system for deformation and stress of deep foundation pit support structure according to claim 3 is characterized by: The equivalent modulus change sequence is extracted to determine the equivalent modulus change rate and the structural stiffness evolution trend is determined. The specific steps are as follows: Determine the support structure according to the variation of equivalent modulus; If the equivalent modulus variation is stable, the support structure is in the normal elastic response stage; If the equivalent modulus drops rapidly, the support structure is in a nonlinear, degenerate or unstable stage; Obtain the equivalent modulus sequence obtained by inversion processing, and use the first-order derivative of the equivalent modulus with time as the equivalent modulus change rate; The structural stiffness evolution trend is determined based on the rate of change of the equivalent modulus.

5. The intelligent monitoring system for deformation and stress of deep foundation pit support structure according to claim 4 is characterized in that: Determining the structural stiffness evolution trend based on the equivalent modulus change rate includes the following steps: If the rate of change of the equivalent modulus is less than 0, it means that the stiffness of the deep foundation pit support structure is in a weakening trend; If the absolute value of the equivalent modulus change rate increases, it indicates that the stiffness evolution of the deep foundation pit support structure is discontinuous, and it is easy to have a sudden change in the structural state or an external interference event; If the rate of change of the equivalent modulus remains unchanged, it means that the structural stiffness maintains a stable trend and is in the safety response stage.

6. The intelligent monitoring system for deformation and stress of deep foundation pit support structure according to claim 5 is characterized by: It is used to construct the modulus change rate field based on the equivalent modulus change rate, and to set the partition threshold in combination with the disturbance sensitivity factor to identify and spatially locate the structural abnormality area. The specific steps are as follows: The monitoring position of the deep foundation pit support structure and the rate of change of the equivalent modulus are combined into a set of measuring points; Using local structure related interpolation to check the set of measuring points, spatial interpolation is performed to determine the modulus change rate values ​​of different monitoring points, and the modulus change rate spatial field is constructed according to the modulus change rate values; A regional modulus change rate judgment threshold is set and compared with the modulus change rate value to determine whether there is any abnormal change in the current state of the support structure.

7. The intelligent monitoring system for deformation and stress of deep foundation pit support structure according to claim 6 is characterized by: Set a regional modulus change rate judgment threshold and compare it with the modulus change rate value to determine whether there is an abnormal change in the current state of the support structure. The specific steps are as follows: If the modulus change rate value exceeds the modulus change rate judgment threshold, it means that there is a risk of abnormal structural performance in the detection area and it is marked as an abnormal area; After judging all monitoring points, a structural stiffness anomaly distribution map is generated, and the identified abnormal areas are marked to form a spatial anomaly mask layer or risk heat map.

8. The intelligent monitoring system for deformation and stress of deep foundation pit support structure according to claim 7 is characterized by: The hierarchical response strategy is triggered based on the results of the structural behavior analysis. The specific steps are as follows: When the structural response distortion index is less than the structural response distortion threshold and the structural response hysteresis index is less than the structural response hysteresis threshold, the support structure does not need to be adjusted and monitoring continues; When the structural response distortion index is greater than or equal to the structural response distortion threshold and the structural response hysteresis index is less than the structural response hysteresis threshold, the entire structure is still in a fluctuating state, and the frequency of change trends in the monitoring support structure area is increased; When the structural response distortion index is less than the structural response distortion threshold and the structural response hysteresis index is greater than or equal to the structural response hysteresis threshold, the data collection frequency is increased and long-term monitoring is carried out; When the structural response distortion index is greater than or equal to the structural response distortion threshold and the structural response hysteresis index is greater than or equal to the structural response hysteresis threshold, it is necessary to immediately trigger an early warning and take enhanced detection or emergency assessment measures.

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