Underground pipeline protection analysis system and method based on excavation state of foundation pit

Abstract

The invention relates to the field of civil engineering, in particular to an underground pipeline protection analysis system and method based on the excavation state of a foundation pit, and the system comprises a soil parameter analysis module, an underground water level analysis module, a vibration data acquisition module, a model construction module and a management database. The method comprises the following steps: estimating ground settlement according to elevation data of each measurement point of an excavated part of a foundation pit, judging whether a pipeline has safety risks, measuring the linear correlation degree of an underground water level and the ground settlement according to the underground water level at each measurement time, and obtaining each piece of vibration data and relative displacement data of the pipeline under each piece of vibration data; the pipeline risk assessment model is constructed according to the input variables and the output variables of the model, then the comprehensive risk level of the pipeline is output, the pipeline risk assessment model is constructed through the input variables and the output variables, the mapping relation from multi-source data to the risk assessment result is established, and risk assessment is more objective and accurate.

Description

Technical Field

[0001] The present invention relates to the field of civil engineering, and in particular to an underground pipeline protection analysis system and method based on foundation pit excavation status. Background Art

[0002] Existing technologies have certain limitations in the protection of underground pipelines. Some methods focus on the construction operation process and lack comprehensive analysis of complex factors in the foundation pit excavation process.

[0003] For example, the existing Chinese patent with application number 202310731501.6 discloses a construction excavation method for preventing deformation of underground pipelines in foundation pits. This scheme performs three-dimensional modeling of underground pipelines within the vicinity of the excavation construction, simulates and analyzes the construction process through simulation, and predicts the safety of underground pipelines, thereby ensuring the safety of subsequent underground pipeline excavation construction.

[0004] However, the patent has the following problems: although the solution has established a three-dimensional finite element analysis model and includes an elastic foundation beam model to analyze the interaction between underground pipelines and soil media, the elastic foundation beam model is mainly a static analysis model, which mainly considers the effect of the final displacement of the soil on the pipeline. It does not take into account the unevenness of soil settlement during foundation pit excavation, and it is difficult to accurately reflect the impact of settlement on pipelines in actual situations.

[0005] For example, the existing Chinese patent with application number 202310626883.6 discloses a method for calculating the deformation of adjacent underground pipelines caused by foundation pit excavation taking into account damage and aging. This scheme obtains the settlement of adjacent underground pipelines caused by foundation pit excavation through the deformation of the foundation pit retaining structure, and considers the aging factor by reducing the overall stiffness of the pipeline, and considers the pipeline damage factor by reducing the stiffness of some positions of the pipeline, which enriches the research on the influence of foundation pit excavation on the deformation of adjacent underground pipelines, and the calculated deformation of adjacent underground pipelines caused by foundation pit excavation is more reliable.

[0006] However, the patent has the following problems: when analyzing the deformation of the foundation pit, the scheme only uses the cumulative maximum deformation and the excavation depth ratio as the control parameters for fitting, which may not be able to fully and accurately reflect all influencing factors. In actual projects, the deformation of the side walls of the foundation pit may also be affected by a combination of factors such as soil properties and groundwater changes, which may lead to inaccurate prediction results. Summary of the invention

[0007] In order to overcome the shortcomings of the background technology, the embodiments of the present invention provide an underground pipeline protection analysis system and method based on the foundation pit excavation status, which can effectively solve the problems involved in the above-mentioned background technology.

[0008] The purpose of the present invention can be achieved through the following technical solutions: The present invention provides an underground pipeline protection analysis system based on the foundation pit excavation status, including: a soil parameter analysis module, which is used to generate a soil data measurement record form based on the foundation pit soil data, estimate the surface settlement, and then perform a risk assessment on the pipeline bending stress and axial strain.

[0009] The groundwater level analysis module is used to obtain groundwater level data, correlate it with surface settlement, and measure the linear correlation between groundwater level and surface settlement.

[0010] The vibration data acquisition module is used to acquire various vibration data and relative displacement data of the pipeline under each vibration data.

[0011] The model building module is used to construct a pipeline risk assessment model using foundation pit soil data, pipeline data, groundwater level data, and vibration data as input variables, and output the comprehensive risk level of the pipeline.

[0012] The management database is used to store the empirical coefficients of soil types corresponding to each soil type, the set elastic modulus and pipeline diameter of the pipeline.

[0013] Preferably, the soil parameter analysis module specifically includes the following steps: S1. Selecting a number of measuring points in the excavation area of ​​the foundation pit according to the principle of equal spacing. During the excavation of the foundation pit, measuring the elevation data of each measuring point in the excavated part of the foundation pit by a total station according to the set monitoring time interval, recording the coordinates, elevation and measurement time of each measuring point, and forming a measurement record table.

[0014] S2. Calculate the excavated depth of the foundation pit based on the elevation data of each measuring point at the current measuring time, and simultaneously obtain the length and width of the foundation pit. Calculate the soil excavation volume of the foundation pit in combination with the excavated depth of the foundation pit, so as to estimate the surface settlement.

[0015] S3. Analyze the bending stress of the pipeline according to the uniformity of surface settlement, obtain the safety factor of the pipeline, and determine the risk level of the pipeline.

[0016] S4. Analyze the axial strain of the pipeline according to the surface settlement at both ends of the pipeline, and determine whether there is a safety risk in the pipeline according to the set threshold. If so, calculate the risk strain value of the pipeline.

[0017] Preferably, the specific operation method of step S2 is: record the excavated depth of the foundation pit as , and at the same time obtain the length and width of the foundation pit, calculate the soil excavation volume of the foundation pit in combination with the excavated depth of the foundation pit, obtain the soil type of the foundation pit soil, match it with the corresponding soil type empirical coefficients of each soil type stored in the management database, and obtain the soil type empirical coefficient of the foundation pit soil, recorded as , and then the soil loss volume of the foundation pit is obtained according to the set soil loss rate , through the formula Calculate the surface settlement at each excavation point , Indicates The number of the excavation point, ,in represents the maximum surface settlement, , represents the sedimentation tank width coefficient, , Indicates The distance between the excavation point and the center of the foundation pit, represents pi, Represents a natural constant.

[0018] Preferably, the specific operation method of step S3 is: S31. Read the surface settlement of each excavation point , the average surface settlement is obtained by averaging, which is recorded as , through the formula Get the uniformity of surface settlement ,in Indicates the number of excavation points.

[0019] S32. Taking adjacent excavation points as a group, calculate the surface settlement difference and horizontal distance of each group of adjacent excavation points, and obtain the pipeline bending curvature of each group of adjacent excavation points by dividing the surface settlement difference of each group of adjacent excavation points by the horizontal distance of the corresponding group of adjacent excavation points. Calculate the mean value and then take the inverse to obtain the bending curvature radius, which is recorded as , extract the set pipeline elastic modulus from the management database and pipeline diameter , calculate the pipeline bending stress : .

[0020] S33. Obtain the set pipeline yield strength, divide it by the pipeline bending stress to obtain the pipeline safety factor, set the safety factor threshold, if the pipeline safety factor is greater than or equal to the set safety factor threshold, it means that the risk level of the pipeline is low risk, if the pipeline safety factor is less than the set safety factor threshold, it means that the risk level of the pipeline is high risk.

[0021] Preferably, the specific operation method of step S4 is: S41. Obtain the original length of the pipeline At the same time, the distances between the two ends of the pipeline and the center of the foundation pit are obtained to calculate the surface settlement at both ends of the pipeline , and the settlement difference at both ends of the pipeline is obtained by subtracting it. , substitute into the formula to calculate the axial strain of the pipeline : .

[0022] S42. Set the allowable strain threshold of the pipeline under design conditions. If the axial strain of the pipeline is less than or equal to the allowable strain threshold of the pipeline under design conditions, it means that the pipeline is in a safe state, and the risk strain value of the pipeline is recorded as 0. If the axial strain of the pipeline is greater than the allowable strain threshold of the pipeline under design conditions, it means that there is a safety risk in the pipeline. The risk strain value of the pipeline is obtained by dividing the axial strain of the pipeline by the allowable strain threshold of the pipeline under design conditions.

[0023] Preferably, the specific operation method of the groundwater level analysis module is: extract the elevation data of each measurement point corresponding to each measurement time from the measurement record table, and analyze and obtain the maximum surface settlement at each measurement time. , Indicates The number of the measurement time, , several groundwater level monitoring wells are arranged at each measuring point, and the groundwater level at each measuring point at each measuring time is obtained by using a water level meter. The groundwater level at each measuring time is obtained after the mean calculation, and the mapping of the maximum surface settlement at each measuring time and the groundwater level is obtained one by one. The linear correlation between the groundwater level and the surface settlement is measured by the Pearson correlation coefficient: ,in Indicates The groundwater level at the measurement time, They represent the maximum surface settlement and the average value of groundwater level respectively.

[0024] Preferably, the specific operation method of the vibration data acquisition module is: according to the principle of equal spacing, a number of vibration measurement points are set along the direction of the underground pipeline, the sampling time is set, and the vibration data generated by the construction machinery at each vibration measurement point within the sampling time is obtained through the vibration sensor, and the mean value is calculated to obtain each vibration data. For each vibration data, the displacement of the two ends of the pipeline under each vibration data is measured at the same time, and the relative displacement data of the pipeline under each vibration data is obtained by subtracting them.

[0025] Preferably, the specific analysis method of the input variables and output variables of the model is: determine the input variables of the model, including foundation pit soil data, pipeline data, groundwater level data, and vibration data, wherein the foundation pit soil data include the excavation depth, length, width, and surface settlement of the foundation pit; the pipeline data include the original length of the pipeline and the distance between the two ends of the pipeline and the center point of the foundation pit; the groundwater level data include the groundwater level at each measuring point at each measuring time; and the vibration data include various vibration data.

[0026] The impact assessment results on underground pipelines are used as the output variables of the model, including the safety factor and risk level of the pipeline, the risk strain value of the pipeline, the linear correlation between the groundwater level and the surface settlement, and the relative displacement data of the pipeline under various vibration data.

[0027] Preferably, the specific operation method of the model building module is: normalizing the input variables and output variables of the model to obtain the processed values ​​of the input variables and output variables of the model, forming an input feature set and an output variable set according to the processed values ​​of the input variables and output variables of the model, assigning a weight factor to each data in the output variable set, and obtaining a comprehensive risk assessment index of the pipeline by accumulating the product of each data in the output variable set with its corresponding weight factor, and obtaining a comprehensive risk level of the pipeline by matching the comprehensive risk assessment index range corresponding to each set comprehensive risk level.

[0028] The input feature set, output variable set, and comprehensive risk level of the pipeline are input into the neural network in batches for training to generate a pipeline risk assessment model. By inputting the real-time input feature set into the pipeline risk assessment model, the output variable set and the final comprehensive risk level of the pipeline are obtained.

[0029] Preferably, the present invention provides an underground pipeline protection analysis method based on the foundation pit excavation status, and the specific steps of the analysis method are as follows: A1. Generate a soil data measurement record form based on the foundation pit soil data, estimate the surface settlement, and then conduct a risk assessment on the pipeline bending stress and axial strain.

[0030] A2. Obtain groundwater level data, correlate it with surface settlement, and measure the linear correlation between groundwater level and surface settlement.

[0031] A3. Obtain each vibration data and the relative displacement data of the pipeline under each vibration data.

[0032] A4. Use foundation pit soil data, pipeline data, groundwater level data, and vibration data as input variables to construct a pipeline risk assessment model and output the comprehensive risk level of the pipeline.

[0033] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: 1. The present invention estimates the surface settlement based on the elevation data of each measuring point in the excavated part of the foundation pit, determines whether there is a safety risk to the pipeline, predicts the safety risk of the pipeline in advance, avoids possible damage to the pipeline due to surface settlement, reduces the adverse effects caused by pipeline damage, and ensures the normal operation of related facilities.

[0034] 2. The present invention measures the linear correlation between the groundwater level and the surface settlement according to the groundwater level at each measuring time, which helps to gain a deeper understanding of the relationship between the groundwater level and the surface settlement, thereby preventing pipeline safety risks that may be caused by changes in surface settlement caused by changes in the groundwater level.

[0035] 3. The present invention can timely discover abnormal pipeline displacement caused by vibration by acquiring various vibration data and relative displacement data of the pipeline under each vibration data, and prevent accidents such as pipeline rupture and leakage.

[0036] 4. The present invention constructs a pipeline risk assessment model based on the input variables and output variables of the model, and then outputs the comprehensive risk level of the pipeline, integrates complex factors into an assessment system, constructs a pipeline risk assessment model through output variables, and establishes a mapping relationship from multi-source data to risk assessment results, making risk assessment more objective and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0038] Figure 1 It is a module connection diagram of an underground pipeline protection analysis system based on foundation pit excavation status.

[0039] Figure 2 for Figure 1 Flowchart of the soil parameter analysis module.

[0040] Figure 3 The figure is a flow chart of an underground pipeline protection analysis method based on foundation pit excavation status. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0042] See also Figure 1 As shown, an underground pipeline protection analysis system based on foundation pit excavation status includes a soil parameter analysis module, a groundwater level analysis module, a vibration data acquisition module, a model building module, and a management database.

[0043] The management database is connected with the soil parameter analysis module, the groundwater level analysis module, the vibration data acquisition module and the model construction module, and the model construction module is connected with the soil parameter analysis module, the groundwater level analysis module and the vibration data acquisition module.

[0044] The soil parameter analysis module is used to generate soil data measurement record tables based on foundation pit soil data, estimate the surface settlement, and then conduct risk assessment on pipeline bending stress and axial strain.

[0045] See also Figure 2 As shown, the soil parameter analysis module specifically includes the following steps: S1. Selecting a number of measuring points in the excavation area of ​​the foundation pit according to the principle of equal spacing; during the excavation of the foundation pit, measuring the elevation data of each measuring point in the excavated part of the foundation pit by a total station according to the set monitoring time interval, recording the coordinates, elevation and measurement time of each measuring point, and forming a measurement record table; the formed measurement record table provides raw data for subsequent calculations and analysis, and is the basis of the entire analysis process.

[0046] Assuming that the monitoring time interval is 15 minutes, the simulation results can be obtained. Please refer to Table 1 for details. Table 1 lists some representative data.

[0047] Table 1. Elevation data of some collected measurement points

[0048]

[0049] S2. Calculate the excavated depth of the foundation pit based on the elevation data of each measuring point at the current measuring time, and obtain the length and width of the foundation pit at the same time. Calculate the soil excavation volume of the foundation pit in combination with the excavated depth of the foundation pit, and estimate the surface settlement. Accurate calculation of the excavated depth and soil excavation volume helps to grasp the progress of the project, and also provides key parameters for evaluating the impact of the project on the surrounding environment (such as surface settlement). The estimation of surface settlement can provide early warning of the possible impact of the project on the surrounding area, so as to adjust the construction strategy in time and protect surrounding buildings and underground pipelines and other facilities.

[0050] S3. Analyze the bending stress of the pipeline according to the uniformity of surface settlement, obtain the safety factor of the pipeline, and judge the risk level of the pipeline. It can be discovered in advance whether the pipeline has the risk of excessive bending deformation due to uneven surface settlement. The calculation of the safety factor intuitively reflects the safety margin of the pipeline.

[0051] S4. Analyze the axial strain of the pipeline according to the surface settlement at both ends of the pipeline, and determine whether there is a safety risk in the pipeline according to the set threshold. If so, calculate the risk strain value of the pipeline; it can accurately evaluate the deformation risk of the pipeline in the axial direction, and provide an important basis for judging whether the pipeline needs reinforcement, adjustment or other protection measures. The determination of the risk strain value helps to optimize the underground pipeline protection plan, reduce pipeline damage caused by excessive axial strain, and ensure the normal operation of underground pipelines.

[0052] The specific operation method of step S2 is: record the excavated depth of the foundation pit as , and at the same time obtain the length and width of the foundation pit, calculate the soil excavation volume of the foundation pit in combination with the excavated depth of the foundation pit, obtain the soil type of the foundation pit soil, match it with the corresponding soil type empirical coefficients of each soil type stored in the management database, and obtain the soil type empirical coefficient of the foundation pit soil, recorded as , and then the soil loss volume of the foundation pit is obtained according to the set soil loss rate , through the formula Calculate the surface settlement at each excavation point , Indicates The number of the excavation point, ,in represents the maximum surface settlement, , represents the sedimentation tank width coefficient, , Indicates The distance between the excavation point and the center of the foundation pit, represents pi, It represents a natural constant; the distance from the center of the foundation pit reflects the influence of spatial position on the settlement, which helps to discover in advance the areas that may have a large risk of surface settlement, so that special protection measures can be taken for these areas.

[0053] It should be noted that It is a settlement distribution formula based on spatial position. The principle of this formula is that foundation pit excavation will lead to soil loss, which in turn causes surface settlement. On the plane based on the center of the foundation pit, the distribution of settlement is not uniform. The closer the location is to the center of the foundation pit, the greater the impact of soil loss and the greater the surface settlement. Represents a natural constant, which is the base of an exponential function. In this formula, it is used to construct an exponential decay relationship between the amount of sedimentation and the distance. As the surface temperature increases, the settlement decreases according to the law of exponential decay. This formula can be used to calculate the surface settlement of each excavation point.

[0054] It should be noted that the formula for the maximum surface settlement is derived based on the assumption that the ground loss is evenly distributed along the length of the tunnel and the volume of the surface settlement trough is equal to the ground loss volume. For surface sedimentation tanks, their volumes can be determined by Integrating over the entire surface gives , according to the integral property of the normal distribution function: ,so By shifting the terms, we can get the maximum surface settlement .

[0055] It should be noted that the specific analysis method for the excavation depth of the foundation pit is: measure the elevation of the original ground of the foundation pit, take the average elevation of the elevations of each measuring point at the current measurement time to obtain the average elevation of the foundation pit, and obtain the excavation depth of the foundation pit by subtracting the elevation of the original ground of the foundation pit from the average elevation of the foundation pit.

[0056] It should be noted that in the actual foundation pit excavation project, the soil will not be excavated completely according to the theoretical shape. Due to various factors such as excavation method, soil characteristics, support effect, etc., the actual excavated soil volume will be larger than the theoretically calculated excavation volume. The extra volume is the soil loss volume. The soil loss rate of the foundation pit is generally 0.1%-1% of the excavation volume.

[0057] For soil displacement data, please refer to Table 2, which lists some representative data.

[0058] Table 2. Some collected soil displacement data and calculation results

[0059]

[0060] The specific operation method of step S3 is as follows: S31. Read the surface settlement of each excavation point , the average surface settlement is obtained by averaging, which is recorded as , through the formula Get the uniformity of surface settlement ,in Indicates the number of excavation points.

[0061] It should be noted that in order to measure the degree of dispersion of the surface settlement at each excavation point relative to the average settlement, the surface settlement uniformity formula is introduced, where Indicates the surface settlement at each excavation point The average sedimentation The relative deviations of the standard deviations are calculated by averaging the squares of the squares, and then taking the square root. , the denominator As the dispersion of relative deviation increases, the uniformity of surface settlement increases. As a whole, it decreases with the increase of the discrete degree. The closer it is to 1, the closer the surface settlement at each excavation point is to the average value, and the more uniform the surface settlement is. The smaller it is, the greater the difference in surface settlement at each excavation point relative to the average value, and the more uneven the surface settlement is.

[0062] S32. Taking adjacent excavation points as a group, calculate the surface settlement difference and horizontal distance of each group of adjacent excavation points, and obtain the pipeline bending curvature of each group of adjacent excavation points by dividing the surface settlement difference of each group of adjacent excavation points by the horizontal distance of the corresponding group of adjacent excavation points. Calculate the mean value and then take the inverse to obtain the bending curvature radius, which is recorded as , extract the set pipeline elastic modulus from the management database and pipeline diameter , calculate the pipeline bending stress : The elastic modulus reflects the ability of pipeline materials to resist elastic deformation. The pipeline diameter is a geometric characteristic parameter of the pipeline. The bending stress can be calculated in combination with the bending radius of curvature to accurately describe the bending state of the pipeline. This helps to detect in advance whether the pipeline is at risk of excessive stress due to bending, thereby providing a quantitative basis for taking corresponding protective measures.

[0063] Please refer to Table 3 for details, which lists some representative data.

[0064] Table 3. Some collected pipeline data and axial strain calculation results

[0065]

[0066] S33. Obtain the set pipeline yield strength, divide it by the pipeline bending stress to obtain the pipeline safety factor, set the safety factor threshold, if the pipeline safety factor is greater than or equal to the set safety factor threshold, it means that the risk level of the pipeline is low risk, if the pipeline safety factor is less than the set safety factor threshold, it means that the risk level of the pipeline is high risk.

[0067] It should be noted that the safety factor threshold is set for different application scenarios. In a specific embodiment, for steel structure bridges, the yield strength of steel is relatively high. Considering that the bridge has to bear vehicle loads, wind loads, temperature changes and other complex factors, the safety factor threshold is usually set between 1.5-2.0. For example, Q345 steel has a yield strength of 345MPa. When the calculated structural stress exceeds 172.5-230MPa (345MPa divided by the safety factor threshold of 1.5-2.0), it is necessary to pay attention to the structural risk; for long-distance oil and gas pipelines, since the transported medium has the characteristics of flammable, explosive, toxic and other characteristics, the safety requirements are extremely high. The safety factor threshold is usually set at 2.0-3.0. Assuming that the yield strength of the steel used in a certain section of the pipeline is 410MPa, when the calculated pipeline bending stress or other stress exceeds 136.7-205MPa (410MPa divided by the safety factor threshold of 2.0-3.0), the pipeline is considered to be in a high-risk state.

[0068] The specific operation method of step S4 is as follows: S41. Obtain the original length of the pipeline At the same time, the distances between the two ends of the pipeline and the center of the foundation pit are obtained to calculate the surface settlement at both ends of the pipeline , and the settlement difference at both ends of the pipeline is obtained by subtracting it. , substitute into the formula to calculate the axial strain of the pipeline : Accurately calculating the axial strain of the pipeline can quantify the axial deformation of the pipeline caused by surface settlement, providing key basic data for judging whether the pipeline is safe.

[0069] It should be noted that the axial strain formula of the pipeline calculates the relative axial deformation degree of the pipeline under the influence of the settlement difference at both ends, that is, the axial strain, which reflects the elongation or shortening of the pipeline in the axial direction under the influence of the settlement difference in the vertical direction. It indicates the actual increase in length of the pipeline due to the settlement difference at both ends. The part under the square root is The calculated length is the length of the pipeline after deformation after considering the settlement difference, minus the original length We get the change in length, the denominator It is the original length of the pipeline and is used as a reference length to measure the relative size of the length change.

[0070] S42. Set the allowable strain threshold of the pipeline under design conditions. If the axial strain of the pipeline is less than or equal to the allowable strain threshold of the pipeline under design conditions, it means that the pipeline is in a safe state, and the risk strain value of the pipeline is recorded as 0. If the axial strain of the pipeline is greater than the allowable strain threshold of the pipeline under design conditions, it means that there is a safety risk in the pipeline. The risk strain value of the pipeline is obtained by dividing the axial strain of the pipeline by the allowable strain threshold of the pipeline under design conditions. The allowable strain threshold is a safety limit determined based on the design conditions of the pipeline. By comparison, it can be intuitively judged whether the pipeline is within the safety range. The risk strain value quantifies the degree to which the pipeline exceeds the safety range.

[0071] It should be noted that the allowable strain threshold of the pipeline under design conditions is set according to the material of the pipeline. For common steel pipes for transporting oil and gas, when the strain reaches 0.003, the steel pipe begins to show obvious plastic deformation. When it reaches 0.005, local rupture may occur. Taking into account the safety margin, the allowable strain threshold is set to 0.002; for cast iron pipes, cast iron pipes are brittle. Experiments show that when the strain exceeds 0.001, cracks are prone to occur. Taking into account the uncertainty in the project, the allowable strain threshold is set to 0.0008 to ensure the safety of cast iron pipes under various working conditions and avoid rupture due to excessive strain; for plastic pipes, taking the common polyethylene plastic pipe as an example, it has good flexibility. Through experiments and engineering practice, it is found that when the strain reaches 0.004, the performance of the pipe begins to decline. When it reaches 0.006, irreversible deformation may occur. Setting the allowable strain threshold to 0.003 can not only give full play to its flexibility advantage, but also ensure safety in long-term use.

[0072] The groundwater level analysis module is used to obtain groundwater level data, correlate it with surface settlement, and measure the linear correlation between groundwater level and surface settlement.

[0073] The specific operation method of the groundwater level analysis module is: extract the elevation data of each measurement point corresponding to each measurement time from the measurement record table, and analyze and obtain the maximum surface settlement at each measurement time. , Indicates The number of the measurement time, , several groundwater level monitoring wells are arranged at each measuring point, and the groundwater level at each measuring point at each measuring time is obtained by using a water level meter. The groundwater level at each measuring time is obtained after the mean calculation, and the mapping of the maximum surface settlement at each measuring time and the groundwater level is obtained one by one. The linear correlation between the groundwater level and the surface settlement is measured by the Pearson correlation coefficient: ,in Indicates The groundwater level at the measurement time, They respectively represent the maximum surface settlement and the average value of the groundwater level; the rise or fall of the groundwater level may cause the expansion or contraction of the soil, which in turn affects the surface settlement, which is conducive to predicting the development of surface settlement and timely discovering possible safety hazards.

[0074] It should be noted that the Pearson correlation coefficient is used to measure the linear correlation between two variables. Its derivation is based on the concepts of covariance and standard deviation. It represents g times the covariance of the maximum surface settlement and the groundwater level, reflecting whether the change trends of the two are consistent. When the numerator is positive, it means that the maximum surface settlement and the groundwater level tend to rise or fall at the same time. When the numerator is negative, it means that one tends to rise while the other falls. It is g times the product of the maximum surface settlement and the standard deviation of the groundwater level, which plays a role in standardization, making the value of the correlation coefficient Within the range, when When it is close to 1, it indicates that there is a strong positive linear correlation between the groundwater level and the surface settlement, that is, as the groundwater level rises, the surface settlement tends to increase. When it is close to -1, it means that there is a strong negative linear correlation between the groundwater level and the surface settlement, that is, when the groundwater level rises, the surface settlement tends to decrease. When it is close to 0, it means that the linear correlation between groundwater level and surface subsidence is very weak, and there is almost no obvious linear correlation.

[0075] Assuming that the monitoring time interval is 15 minutes, the simulation results can be obtained. Please refer to Table 4 for details. Table 4 lists some representative data.

[0076] Table 4. Some of the collected groundwater level and surface settlement data

[0077]

[0078] The average values ​​of surface subsidence and groundwater level were calculated respectively. , , substitute into the Pearson correlation coefficient formula , It is close to -1, indicating that there is a strong negative correlation between surface subsidence and groundwater level.

[0079] The vibration data acquisition module is used to acquire various vibration data and relative displacement data of the pipeline under each vibration data.

[0080] The specific operation method of the vibration data acquisition module is as follows: according to the principle of equal spacing, a number of vibration measurement points are set along the direction of the underground pipeline, the sampling time is set, and the vibration data generated by the construction machinery at each vibration measurement point within the sampling time is obtained through the vibration sensor, and the mean value is calculated to obtain each vibration data. For each vibration data, the displacement of the two ends of the pipeline under each vibration data is measured at the same time, and the relative displacement data of the pipeline under each vibration data is obtained by subtracting them; this helps to predict the safety status of the pipeline under different vibration intensities and promptly discover possible safety risks.

[0081] It should be noted that each vibration data includes vibration intensity, vibration frequency, and vibration duration.

[0082] The model building module is used to construct a pipeline risk assessment model using foundation pit soil data, pipeline data, groundwater level data, and vibration data as input variables, and output the comprehensive risk level of the pipeline.

[0083] The specific analysis method of the input variables and output variables of the model is: determine the input variables of the model, including foundation pit soil data, pipeline data, groundwater level data, and vibration data, wherein the foundation pit soil data include the excavated depth of the foundation pit, the length and width of the foundation pit, and the surface settlement; the pipeline data include the original length of the pipeline and the distance between the two ends of the pipeline and the center point of the foundation pit; the groundwater level data include the groundwater level at each measuring point at each measuring time; and the vibration data include various vibration data.

[0084] The impact assessment results on underground pipelines are used as the output variables of the model, including the safety factor and risk level of the pipeline, the risk strain value of the pipeline, the linear correlation between the groundwater level and the surface settlement, and the relative displacement data of the pipeline under various vibration data.

[0085] It should be noted that, for the risk level of the pipeline, a corresponding identification value is assigned to each risk level so as to perform unified operations in model calculation and data processing. In a specific embodiment, low risk is set to 1 and high risk is set to 2.

[0086] The specific operation method of the model construction module is as follows: normalizing the input variables and output variables of the model to obtain the processed values ​​of the input variables and output variables of the model, forming an input feature set and an output variable set according to the processed values ​​of the input variables and output variables of the model, assigning weight factors to each data in the output variable set, accumulating the product of each data in the output variable set with its corresponding weight factor, obtaining the comprehensive risk assessment index of the pipeline, and matching it with the corresponding comprehensive risk assessment index range of each set comprehensive risk level to obtain the comprehensive risk level of the pipeline; normalization can avoid certain variables from dominating the model training due to excessive differences in the value range of the variables, thereby affecting the model's learning ability for other variables, clearly distinguishing the input and output parts of the model, and classifying the processed related variables into the input feature set and the output variable set, which is helpful to build the structural framework of the model and determine the flow and use of the data.

[0087] It should be noted that, in a specific embodiment, weight factors are assigned to various data in the output variable set, the weight factor of soil data is set to 0.3, the weight factor of pipeline data is set to 0.25, the weight factor of groundwater level data is set to 0.2, and the weight factor of vibration data is set to 0.25. Uneven soil settlement may cause the pipeline to be partially suspended, thereby causing stress concentration, posing a serious threat to the structural integrity of the pipeline. The pipeline data reflects the material, structural characteristics and risk tolerance of the pipeline itself under design conditions. Under external influences, it is easy to be damaged due to stress concentration. Changes in groundwater level will change the physical and mechanical properties of the soil, such as causing soil softening and changes in effective stress, thereby indirectly affecting the stability of the pipeline. The vibration generated during the construction process will directly act on the pipeline, which may cause problems such as loosening of the pipeline connectors and cracking of the welds. Especially for pipelines made of some brittle materials, the impact of vibration is more significant. Therefore, the weight corresponding to the soil data is the highest, followed by the weights corresponding to the pipeline data and vibration data.

[0088] It should be noted that the specific method of the normalization process is: select the maximum and minimum values ​​of each item from the input variables and output variables of the model, respectively, and record them as , through the formula Perform normalization to obtain the processed values ​​of each item in the model's input variables and output variables , Indicates the input and output variables of the model. The value of the item data, Indicates the input and output variables of the model. The number of the item data, .

[0089] The input feature set, output variable set, and comprehensive risk level of the pipeline are input into the neural network in batches for training to generate a pipeline risk assessment model. By inputting the real-time input feature set into the pipeline risk assessment model, the output variable set and the final comprehensive risk level of the pipeline are obtained; a corresponding relationship between the quantitative comprehensive risk assessment index and the qualitative comprehensive risk level is established, and the numerical results are converted into intuitive risk levels, such as low risk, medium risk, high risk, etc.

[0090] The management database is used to store the empirical coefficients of soil types corresponding to each soil type, the set elastic modulus and pipeline diameter of the pipeline.

[0091] See also Figure 3 As shown, in addition, the present invention provides an underground pipeline protection analysis method based on the foundation pit excavation status, and the specific steps of the analysis method are as follows: A1. Generate a soil data measurement record form based on the foundation pit soil data, estimate the surface settlement, and then conduct a risk assessment on the pipeline bending stress and axial strain.

[0092] A2. Obtain groundwater level data, correlate it with surface settlement, and measure the linear correlation between groundwater level and surface settlement.

[0093] A3. Obtain each vibration data and the relative displacement data of the pipeline under each vibration data.

[0094] A4. Use foundation pit soil data, pipeline data, groundwater level data, and vibration data as input variables to construct a pipeline risk assessment model and output the comprehensive risk level of the pipeline.

[0095] The present invention estimates the surface settlement according to the elevation data of each measuring point in the excavated part of the foundation pit, determines whether there is a safety risk for the pipeline, measures the linear correlation between the groundwater level and the surface settlement according to the groundwater level at each measuring time, obtains each vibration data and the relative displacement data of the pipeline under each vibration data, constructs a pipeline risk assessment model according to the input variables and output variables of the model, and then outputs the comprehensive risk level of the pipeline. The pipeline risk assessment model is constructed through the input and output variables, and a mapping relationship from multi-source data to risk assessment results is established, so that the risk assessment is more objective and accurate.

[0096] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention and they are still covered by the protection scope of the present invention.

Claims

1. An underground pipeline protection analysis system based on foundation pit excavation status, characterized in that: The system specifically includes the following modules: Soil parameter analysis module, which is used to generate soil data measurement record tables based on foundation pit soil data, estimate surface settlement, and then conduct risk assessment on pipeline bending stress and axial strain; The groundwater level analysis module is used to obtain groundwater level data, correlate it with surface settlement, and measure the linear correlation between groundwater level and surface settlement; A vibration data acquisition module, used to acquire various vibration data and relative displacement data of pipelines under various vibration data; The model building module is used to construct a pipeline risk assessment model using foundation pit soil data, pipeline data, groundwater level data, and vibration data as input variables, and output the comprehensive risk level of the pipeline; The management database is used to store the empirical coefficients of each soil type, the set elastic modulus and pipeline diameter of the pipeline.

2. The underground pipeline protection analysis system based on foundation pit excavation status according to claim 1 is characterized by: The soil parameter analysis module specifically includes the following steps: S1. Select several measuring points in the excavation area of ​​the foundation pit according to the principle of equal spacing. During the excavation of the foundation pit, measure the elevation data of each measuring point in the excavated part of the foundation pit by a total station according to the set monitoring time interval, record the coordinates, elevation and measurement time of each measuring point, and generate a soil data measurement record table; S2. Calculate the excavated depth of the foundation pit according to the elevation data of each measuring point at the current measuring time, obtain the length and width of the foundation pit, and calculate the excavated volume of the foundation pit in combination with the excavated depth of the foundation pit, so as to estimate the surface settlement; S3. Analyze the bending stress of the pipeline according to the uniformity of surface settlement, obtain the safety factor of the pipeline, and determine the risk level of the pipeline; S4. Analyze the axial strain of the pipeline according to the surface settlement at both ends of the pipeline, and determine whether there is a safety risk in the pipeline according to the set threshold. If so, calculate the risk strain value of the pipeline.

3. The underground pipeline protection analysis system based on foundation pit excavation status according to claim 2 is characterized by: The specific operation method of step S2 is: The excavated depth of the foundation pit is recorded as , and at the same time obtain the length and width of the foundation pit, calculate the soil excavation volume of the foundation pit in combination with the excavated depth of the foundation pit, obtain the soil type of the foundation pit soil, match it with the corresponding soil type empirical coefficients of each soil type stored in the management database, and obtain the soil type empirical coefficient of the foundation pit soil, recorded as , and then the soil loss volume of the foundation pit is obtained according to the set soil loss rate , through the formula Calculate the surface settlement at each excavation point , Indicates The number of the excavation point, ,in represents the maximum surface settlement, , represents the sedimentation tank width coefficient, , Indicates The distance between the excavation point and the center of the foundation pit, represents pi, Represents a natural constant.

4. The underground pipeline protection analysis system based on foundation pit excavation status according to claim 2 is characterized in that: The specific operation method of step S3 is: S31. Read the surface settlement of each excavation point , the average surface settlement is obtained by averaging, which is recorded as , through the formula Get the uniformity of surface settlement ,in Indicates the number of excavation points; S32. Taking adjacent excavation points as a group, calculate the surface settlement difference and horizontal distance of each group of adjacent excavation points, and obtain the pipeline bending curvature of each group of adjacent excavation points by dividing the surface settlement difference of each group of adjacent excavation points by the horizontal distance of the corresponding group of adjacent excavation points. Calculate the mean value and then take the inverse to obtain the bending curvature radius, which is recorded as , extract the set pipeline elastic modulus from the management database and pipeline diameter , calculate pipeline bending stress : ; S33. Obtain the set pipeline yield strength, divide it by the pipeline bending stress to obtain the pipeline safety factor, set the safety factor threshold, if the pipeline safety factor is greater than or equal to the set safety factor threshold, it means that the risk level of the pipeline is low risk, if the pipeline safety factor is less than the set safety factor threshold, it means that the risk level of the pipeline is high risk.

5. The underground pipeline protection analysis system based on foundation pit excavation status according to claim 2 is characterized by: The specific operation method of step S4 is: S41. Get the original length of the pipeline At the same time, the distances between the two ends of the pipeline and the center of the foundation pit are obtained to calculate the surface settlement at both ends of the pipeline , and the settlement difference at both ends of the pipeline is obtained by subtracting it. , substitute into the formula to calculate the axial strain of the pipeline : ; S42. Set the allowable strain threshold of the pipeline under design conditions. If the axial strain of the pipeline is less than or equal to the allowable strain threshold of the pipeline under design conditions, it means that the pipeline is in a safe state, and the risk strain value of the pipeline is recorded as 0. If the axial strain of the pipeline is greater than the allowable strain threshold of the pipeline under design conditions, it means that there is a safety risk in the pipeline. The risk strain value of the pipeline is obtained by dividing the axial strain of the pipeline by the allowable strain threshold of the pipeline under design conditions.

6. The underground pipeline protection analysis system based on foundation pit excavation status according to claim 3 is characterized by: The specific operation method of the groundwater level analysis module is as follows: Extract the elevation data of each measuring point corresponding to each measuring time from the measurement record table, and use this to analyze and obtain the maximum surface settlement at each measuring time. , Indicates The number of the measurement time, , several groundwater level monitoring wells are arranged at each measuring point, and the groundwater level at each measuring point at each measuring time is obtained by using a water level meter. The groundwater level at each measuring time is obtained after the mean calculation, and the mapping of the maximum surface settlement at each measuring time and the groundwater level is obtained one by one. The linear correlation between the groundwater level and the surface settlement is measured by the Pearson correlation coefficient: ,in Indicates The groundwater level at the measurement time, They represent the maximum surface settlement and the average value of groundwater level respectively.

7. The underground pipeline protection analysis system based on foundation pit excavation status according to claim 1 is characterized by: The specific operation method of the vibration data acquisition module is as follows: According to the principle of equal spacing, several vibration measurement points are set along the direction of the underground pipeline, and the sampling time is set. The vibration data generated by the construction machinery at each vibration measurement point within the sampling time is obtained through the vibration sensor, and the mean calculation is performed to obtain each vibration data. For each vibration data, the displacement of the two ends of the pipeline under each vibration data is measured at the same time, and the relative displacement data of the pipeline under each vibration data is obtained by subtracting them.

8. The underground pipeline protection analysis system based on foundation pit excavation status according to claim 1 is characterized by: The specific analysis method of the input variables and output variables of the model is: Determine the input variables of the model, including foundation pit soil data, pipeline data, groundwater level data, and vibration data, wherein the foundation pit soil data includes the excavated depth, length, width, and surface settlement of the foundation pit; the pipeline data includes the original length of the pipeline and the distance between the two ends of the pipeline and the center point of the foundation pit; the groundwater level data includes the groundwater level at each measuring point at each measuring time; and the vibration data includes each vibration data; The impact assessment results on underground pipelines are used as the output variables of the model, including the safety factor and risk level of the pipeline, the risk strain value of the pipeline, the linear correlation between the groundwater level and the surface settlement, and the relative displacement data of the pipeline under various vibration data.

9. The underground pipeline protection analysis system based on foundation pit excavation status according to claim 8 is characterized by: The specific operation method of the model building module is: The input variables and output variables of the model are normalized to obtain the processed values ​​of the input variables and output variables of the model. The input feature set and the output variable set are formed according to the processed values ​​of the input variables and output variables of the model. A weight factor is assigned to each data in the output variable set. The comprehensive risk assessment index of the pipeline is obtained by accumulating the product of each data in the output variable set and its corresponding weight factor. The comprehensive risk level of the pipeline is obtained by matching it with the corresponding comprehensive risk assessment index range of each set comprehensive risk level. The input feature set, output variable set, and comprehensive risk level of the pipeline are input into the neural network in batches for training to generate a pipeline risk assessment model. By inputting the real-time input feature set into the pipeline risk assessment model, the output variable set and the final comprehensive risk level of the pipeline are obtained.

10. An underground pipeline protection analysis method based on foundation pit excavation status, the specific steps of the analysis method are as follows: A1. Generate soil data measurement record form based on foundation pit soil data, estimate surface settlement, and then conduct risk assessment on pipeline bending stress and axial strain; A2. Obtain groundwater level data, correlate it with surface settlement, and measure the linear correlation between groundwater level and surface settlement; A3. Obtaining the vibration data and the relative displacement data of the pipeline under each vibration data; A4. Use foundation pit soil data, pipeline data, groundwater level data, and vibration data as input variables to construct a pipeline risk assessment model and output the comprehensive risk level of the pipeline.

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