An underground pipeline protection analysis system and method based on foundation pit excavation status

Abstract

The present invention relates to the field of civil engineering, and in particular to an underground pipeline protection analysis system and method based on the excavation state of a foundation pit, comprising a soil parameter analysis module, a groundwater level analysis module, a vibration data acquisition module, a model construction module, and a management database. The present invention estimates the surface settlement amount according to the elevation data of each measuring point of the excavated part of the foundation pit, judges whether there is a safety risk for the pipeline, measures the linear correlation degree between the groundwater level and the surface settlement amount 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, constructs the pipeline risk assessment model through the input and output variables, establishes a mapping relationship from multi-source data to risk assessment results, and makes the risk assessment more objective and accurate.

Description

Technical Field

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

[0002] There are certain limitations in the existing technology for underground pipeline protection. Some methods focus on the construction operation process and lack comprehensive analysis of complex factors during the foundation pit excavation process.

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

[0004] However, there are the following problems in this patent: Although this solution establishes a three-dimensional finite element analysis model and includes an elastic foundation beam model to analyze the interaction between the underground pipeline and the soil medium, the elastic foundation beam model is mainly a static analysis model, mainly considering the effect of the final displacement of the soil on the pipeline, and insufficiently considering situations such as the unevenness of soil settlement during the foundation pit excavation process, making it difficult to accurately reflect the impact of settlement on the pipeline in actual situations.

[0005] For example, the existing Chinese patent with the application number 202310626883.6 discloses a calculation method for the deformation of adjacent underground pipelines caused by foundation pit excavation considering damage and aging. This solution 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 the pipeline damage factor by reducing the stiffness of some positions of the pipeline, enriching the research on the influence of foundation pit excavation on the deformation of adjacent underground pipelines, and making the calculation of the deformation of adjacent underground pipelines caused by foundation pit excavation more reliable.

[0006] However, there are the following problems in this patent: This solution only uses the ratio of the cumulative maximum deformation to the excavation depth as a control parameter for fitting when analyzing the foundation pit deformation, which may not comprehensively and accurately reflect all influencing factors. In actual engineering, the deformation of the foundation pit side wall may also be comprehensively affected by various 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 in the background art, the embodiments of the present invention provide an underground pipeline protection analysis system and method based on the foundation pit excavation state, which can effectively solve the problems involved in the above background art.

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

[0009] An underground water level analysis module, which is used to obtain the underground water level data, correlate it with the surface settlement amount, and measure the linear correlation degree between the underground water level and the surface settlement amount.

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

[0011] A model construction module, which is used to construct a pipeline risk assessment model with the foundation pit soil data, pipeline data, underground water level data, and vibration data as input variables, and output the comprehensive risk level of the pipeline.

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

[0013] Preferably, the soil parameter analysis module specifically includes the following steps: S1. Select a number of measurement points in the excavation area of the foundation pit according to the equal-spacing principle. During the foundation pit excavation process, according to the set monitoring time interval, use a total station to measure the elevation data of each measurement point in the excavated part of the foundation pit, record the coordinates, elevation, and measurement time of each measurement point, and form a measurement record form.

[0014] S2. Calculate the excavated depth of the foundation pit according to the elevation data of each measurement point at the current measurement time. At the same time, obtain the length and width of the foundation pit, and 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 amount.

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

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

[0017] Preferably, the specific operation method of step S2 is: Denote 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 soil type empirical coefficients corresponding to each soil type stored in the management database, and obtain the soil type empirical coefficient of the foundation pit soil, denoted as , and then obtain the soil loss volume of the foundation pit according to the set soil loss rate , through the formula Calculate the ground settlement at each excavation point , represents the number of the excavation point, , where represents the maximum ground settlement, , represents the settlement trough width coefficient, , represents the distance from the excavation point to the center point of the foundation pit, represents pi, represents the natural constant.

[0018] Preferably, the specific operation method of step S3 is: S31. Read the ground settlement at each excavation point , calculate the average ground settlement through mean value calculation, denoted as , through the formula Obtain the ground settlement uniformity , where represents the number of excavation points.

[0019] S32. Take adjacent excavation points as a group, calculate the ground settlement difference and horizontal distance of each group of adjacent excavation points, divide the ground settlement difference of each group of adjacent excavation points by the horizontal distance of the corresponding adjacent excavation point group to obtain the pipeline bending curvature of each group of adjacent excavation points, perform mean value calculation on it and then take the reciprocal to obtain the bending curvature radius, denoted as , extract the set pipeline elastic modulus and pipeline diameter , calculate the pipeline bending stress : .

[0020] S33. Obtain the set pipeline yield strength, divide it by the pipeline bending stress to get the safety factor of the pipeline, set the safety factor threshold. If the safety factor of the pipeline is greater than or equal to the set safety factor threshold, it means the risk level of the pipeline is low risk. If the safety factor of the pipeline is less than the set safety factor threshold, it means 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 , and at the same time, obtain the distances from both ends of the pipeline to the center point of the foundation pit respectively, and calculate the ground settlement at both ends of the pipeline , take the difference between them to get the settlement difference at both ends of the pipeline , substitute it into the formula to calculate the axial strain of the pipeline : .

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

[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 form, and analyze the maximum surface settlement amount at each measurement time , represents the number of the th measurement time. Arrange several groundwater level monitoring wells at each measurement point, use a water level gauge to obtain the groundwater level at each measurement point at each measurement time, calculate the mean value to obtain the groundwater level at each measurement time, and obtain the mapping of the maximum surface settlement amount at each measurement time to the groundwater level one by one. Measure the linear correlation degree between the groundwater level and the surface settlement amount through the Pearson correlation coefficient: , where represents the groundwater level at the th measurement time, respectively represent the average values of the maximum surface settlement amount and the groundwater level.

[0024] Preferably, the specific operation method of the vibration data acquisition module is: set several vibration measurement points along the underground pipeline according to the equal spacing principle, set the sampling duration, obtain the vibration data generated by the construction machinery at each vibration measurement point during the sampling duration through a vibration sensor, calculate the mean value to obtain each vibration data, and measure the displacements at both ends of the pipeline under each vibration data. Obtain the relative displacement data of the pipeline under each vibration data by taking the difference.

[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. Among them, the foundation pit soil data includes the excavated depth of the foundation pit, the length and width of the foundation pit, and the surface settlement amount, the pipeline data includes the original length of the pipeline and the distances from both ends of the pipeline to the center point of the foundation pit, the groundwater level data includes the groundwater level at each measurement point at each measurement time, and the vibration data includes each vibration data.

[0026] Taking the evaluation results of the impact on underground pipelines as the output variables of the model, including the safety factor and risk level of the pipelines, the risk response value of the pipelines, the linear correlation degree between the underground water level and the surface settlement amount, and the relative displacement data of the pipelines under each vibration data.

[0027] Preferably, the specific operation method of the model construction module is as follows: perform normalization processing on the input variables and output variables of the model to obtain the processed values of the input variables and output variables of the model, form an input feature set and an output variable set according to the processed values of the input variables and output variables of the model, assign weight factors to each data item in the output variable set, and obtain the comprehensive risk assessment index of the pipeline by accumulating the product of each data item in the output variable set and its corresponding weight factor. By matching with the corresponding comprehensive risk assessment index ranges of each set comprehensive risk level, the comprehensive risk level of the pipeline is obtained.

[0028] Input the input feature set, output variable set, and the comprehensive risk level of the pipeline 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 output.

[0029] Preferably, the present invention provides an analysis method for protecting underground pipelines based on the excavation state of the foundation pit. The specific steps of the analysis method are as follows: A1. Generate a soil data measurement record form according to the foundation pit soil data, estimate the surface settlement amount from it, and then conduct a risk assessment on the pipeline bending stress and axial strain.

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

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

[0032] A4. Use the foundation pit soil data, pipeline data, underground water 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: First, the present invention estimates the surface settlement amount according to the elevation data of each measurement point in the excavated part of the foundation pit, judges whether there is a safety risk for the pipeline, pre-judges the pipeline safety risk in advance, avoids the possible damage to the pipeline caused by the surface settlement, reduces the adverse effects brought by the pipeline damage, and ensures the normal operation of relevant facilities.

[0034] Second, the present invention measures the linear correlation degree between the groundwater level and the ground settlement amount according to the groundwater level at each measurement time, which helps to deeply understand the relationship between the groundwater level and the ground settlement, so as to prevent the pipeline safety risks that may be caused by the ground settlement change due to the change of the groundwater level.

[0035] Third, by obtaining each vibration data and the relative displacement data of the pipeline under each vibration data, the present invention can timely detect the abnormal pipeline displacement caused by vibration and prevent accidents such as pipeline rupture and leakage.

[0036] Fourth, the present invention 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. By integrating complex factors into an evaluation system and constructing a pipeline risk assessment model through output variables, a mapping relationship from multi-source data to risk assessment results is established, making the 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 drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

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

[0039] Figure 2 is Figure 1 the flow chart of the soil parameter analysis module in

[0040] Figure 3 It is a flow chart of an underground pipeline protection analysis method based on the foundation pit excavation state. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0042] Please refer to Figure 1 As shown, an underground pipeline protection analysis system based on the foundation pit excavation state, the analysis system includes a soil parameter analysis module, a groundwater level analysis module, a vibration data acquisition module, a model construction module, and a management database.

[0043] The management database is connected to the soil parameter analysis module, the groundwater level analysis module, the vibration data acquisition module, and the model construction module. The model construction module is connected to 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 a soil data measurement record form based on the foundation pit soil data, estimate the surface settlement amount from it, and then conduct risk assessments on the pipeline bending stress and axial strain.

[0045] Please refer to Figure 2 As shown, the soil parameter analysis module specifically includes the following steps: S1. Select several measurement points in the excavation area of the foundation pit according to the equal-spacing principle. During the excavation of the foundation pit, at the set monitoring time interval, use a total station to measure the elevation data of each measurement point in the excavated part of the foundation pit, record the coordinates, elevation, and measurement time of each measurement point to form a measurement record form; the formed measurement record form provides the original data for subsequent calculations and analyses and is the basis for the entire analysis process.

[0046] Assuming the monitoring time interval is 15 minutes, simulation results can be obtained. Specifically, refer to Table 1, in which some representative data are listed.

[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 measurement point at the current measurement time. At the same time, obtain the length and width of the foundation pit, and 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 amount; accurately calculating the excavated depth and soil excavation volume helps to master the project progress, and at the same time provides key parameters for evaluating the impact of the project on the surrounding environment (such as surface settlement). The surface settlement amount estimation can give early warnings of the possible impacts of the project on the surrounding area, so as to timely adjust the construction strategy and protect facilities such as surrounding buildings and underground pipelines.

[0050] S3. Analyze the pipeline bending stress according to the uniformity of surface settlement, obtain the safety factor of the pipeline, and judge the risk level of the pipeline; it can discover in advance whether there is a risk that the pipeline is bent and deformed too much 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 based on the ground settlement amounts at both ends of the pipeline, determine whether there is a safety risk for the pipeline according to the set threshold, and calculate the risk strain value of the pipeline if there is a risk; it can accurately evaluate the deformation risk of the pipeline in the axial direction, providing an important basis for judging whether the pipeline needs to be reinforced, adjusted 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 the underground pipeline.

[0052] The specific operation method of the 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 empirical coefficients of the corresponding soil types stored in the management database, and obtain the empirical coefficient of the soil type of the foundation pit soil, denoted as , and then obtain the soil loss volume of the foundation pit according to the set soil loss rate , and calculate the ground settlement amount at each excavation point through the formula , , represents the number of the th excavation point, , where represents the maximum ground settlement amount, , represents the settlement trough width coefficient, , represents the distance from the th excavation point to the center point of the foundation pit, represents the pi, represents the natural constant; the distance from the center point of the foundation pit reflects the influence of the spatial position on the settlement amount, which helps to discover in advance the areas where there may be a greater risk of ground settlement, so that special protection measures can be taken for these areas.

[0053] It should be noted that is a settlement distribution formula based on spatial position. The principle of this formula is that the excavation of the foundation pit will cause soil loss, which in turn causes ground settlement. On the plane with the center of the foundation pit as the reference, the distribution of the settlement amount is not uniform. The closer the position is to the center point of the foundation pit, the greater the influence of soil loss, and the greater the ground settlement amount. represents the natural constant, which is the base of the exponential function and is used in this formula to construct the exponential decay relationship of the settlement amount changing with distance. As the distance increases, the settlement amount decreases according to the law of exponential decay. Through this formula, the ground settlement amount at each excavation point can be calculated.

[0054] It should be noted that the formula derivation of the maximum ground settlement is based on the assumption that the ground loss is evenly distributed along the length of the tunnel, and the volume of the ground settlement trough is equal to the volume of the ground loss. , for the ground settlement trough, its volume can be obtained by integrating over the entire ground surface. , according to the integral property of the normal distribution function: , so , by transposing terms, the maximum ground settlement can be obtained. .

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

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

[0057] The soil displacement data is specifically referred to Table 2, in which some representative data are listed.

[0058] Table 2. Part of the collected soil displacement data and calculation results

[0059]

[0060] The specific operation method of step S3 is as follows: S31. Read the ground settlement amount at each excavation point , obtain the average ground settlement amount through mean calculation, denoted as , and obtain the ground settlement uniformity through the formula , where represents the number of excavation points.

[0061] It should be noted that in order to measure the dispersion degree of the ground settlement amount at each excavation point relative to the average settlement amount, the ground settlement uniformity formula is introduced, where represents the ground settlement amount at each excavation point and the relative deviation from the average settlement amount . After squaring and averaging these relative deviations and then taking the square root, based on the calculation idea of the standard deviation, that is , the denominator increases as the degree of dispersion of the relative deviation increases, while the degree of uniformity of ground settlement as a whole decreases as the degree of dispersion increases. When is closer to 1, it indicates that the ground settlement amounts at each excavation point are closer to the average value, and the ground settlement is more uniform. When is smaller, it indicates that the difference in the ground settlement amounts at each excavation point relative to the average value is larger, and the ground settlement is more uneven.

[0062] S32. Taking adjacent excavation points as a group, calculate the ground settlement difference and horizontal distance of each group of adjacent excavation points. By dividing the ground settlement difference of each group of adjacent excavation points by the horizontal distance of the corresponding adjacent excavation point group, the pipeline bending curvature of each group of adjacent excavation points is obtained. After calculating its mean value, the reciprocal is taken to obtain the bending curvature radius, denoted as , extract the set pipeline elastic modulus and pipeline diameter from the management database, and calculate the pipeline bending stress : ; The elastic modulus reflects the ability of the pipeline material to resist elastic deformation. The pipeline diameter is a geometric characteristic parameter of the pipeline. Combining with the bending curvature radius to calculate the bending stress together can accurately describe the bending state of the pipeline, help to detect in advance whether there is a risk of excessive stress caused by bending in the pipeline, and thus provide a quantitative basis for taking corresponding protection measures.

[0063] Specifically refer to Table 3, in which some representative data are listed.

[0064] Table 3. Part of the 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 get the safety factor of the pipeline, set the safety factor threshold. If the safety factor of the pipeline is greater than or equal to the set safety factor threshold, it indicates that the risk level of the pipeline is low risk. If the safety factor of the pipeline is less than the set safety factor threshold, it indicates that the risk level of the pipeline is high risk.

[0067] It should be noted that the set safety factor threshold is set for different application scenarios. In a specific embodiment, for a steel structure bridge, the yield strength of the steel is relatively high. Considering that the bridge has to bear various complex factors such as vehicle loads, wind loads, and temperature changes, the safety factor threshold is usually set between 1.5 and 2.0. For example, for Q345 steel with a yield strength of 345 MPa, when the calculated structural stress exceeds 172.5 - 230 MPa (345 MPa divided by the safety factor threshold of 1.5 - 2.0), the structural risk needs to be concerned. For long-distance oil and gas pipelines, since the transported medium has characteristics such as flammability, explosiveness, and toxicity, the safety requirements are extremely high, and the safety factor threshold is usually set between 2.0 and 3.0. Suppose the yield strength of the steel used in a certain section of the pipeline is 410 MPa. When the calculated pipeline bending stress or other stresses exceed 136.7 - 205 MPa (410 MPa 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 , and at the same time, obtain the distances from both ends of the pipeline to the center point of the foundation pit respectively, and calculate the ground settlement amounts at both ends of the pipeline , take the difference between them to obtain the settlement difference at both ends of the pipeline , and substitute it into the formula to calculate the axial strain of the pipeline : ; accurately calculating the axial strain of the pipeline can quantify the axial deformation situation of the pipeline caused by ground 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 axial relative deformation degree of the pipeline under the action of the settlement difference at both ends, that is, the axial strain, which reflects the elongation or shortening situation of the pipeline in the axial direction under the influence of the settlement difference in the vertical direction. The numerator represents the actual length increase amount of the pipeline due to the settlement difference at both ends. The part under the square root calculates the length of the pipeline after deformation considering the settlement difference, and then subtracting the original length obtains the length change amount. The denominator is the original length of the pipeline, which is used as the 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 indicates 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 indicates that there is a safety risk in the pipeline. By dividing the axial strain of the pipeline by the allowable strain threshold of the pipeline under design conditions, the risk strain value of the pipeline is obtained; the allowable strain threshold is a safety limit determined based on the pipeline design conditions. By comparison, it can be intuitively judged whether the pipeline is within the safe range, and the risk strain value is a quantification of the degree to which the pipeline exceeds the safe range.

[0071] It should be noted that the allowable strain threshold of the pipeline under design conditions is set according to the pipeline material. For common steel pipes for transporting oil and gas, when the strain reaches 0.003, obvious plastic deformation begins to occur in the steel pipe. When it reaches 0.005, local rupture may occur. Considering the safety margin comprehensively, 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 likely to appear. Considering the uncertainties in engineering, 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 common polyethylene plastic pipes as an example, their flexibility is good. Through experiments and engineering practices, it is found that when the strain reaches 0.004, the pipe material performance begins to decline. When it reaches 0.006, irreversible deformation may occur. The allowable strain threshold is set to 0.003, which can not only give play to its flexibility advantage but also ensure safety during long-term use.

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

[0073] The specific operation method of the groundwater level analysis module is as follows: Extract the elevation data corresponding to each measurement point at each measurement time from the measurement record table, and analyze to obtain the maximum surface settlement amount at each measurement time. , denotes the number of the th measurement time. At each measurement point, arrange several groundwater level monitoring wells, use a water level gauge to obtain the groundwater level at each measurement point at each measurement time, calculate the average value to obtain the groundwater level at each measurement time, and obtain the mapping of the maximum surface settlement amount at each measurement time and the groundwater level one by one. Measure the linear correlation degree between the groundwater level and the surface settlement amount through the Pearson correlation coefficient: , where denotes the groundwater level at the th measurement time, respectively represent the maximum surface settlement and the average 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, facilitating the prediction of the development of surface settlement and the timely detection of potential safety hazards.

[0074] It should be noted that the Pearson correlation coefficient is used to measure the linear correlation degree between two variables. Its derivation is based on the concepts of covariance and standard deviation. The numerator 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 simultaneously. When the numerator is negative, it means that the two tend to rise while the other falls. The denominator is g times the product of the standard deviations of the maximum surface settlement and the groundwater level, which plays a role in standardization, making the value of the correlation coefficient within the range. When is close to 1, it indicates a strong positive linear correlation between the groundwater level and the surface settlement amount, that is, when the groundwater level rises, the surface settlement amount tends to increase. When is close to -1, it indicates a strong negative linear correlation between the groundwater level and the surface settlement amount, that is, when the groundwater level rises, the surface settlement amount tends to decrease. When is close to 0, it means that the linear correlation between the groundwater level and the surface settlement amount 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. For specific reference, see Table 4, in which some representative data are listed.

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

[0077]

[0078] Thus, the average values of the surface settlement amount and the groundwater level are calculated respectively 、 , and substituted into the Pearson correlation coefficient formula , is close to -1, indicating a strong negative correlation between the surface settlement amount and the groundwater level.

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

[0080] The specific operation method of the vibration data acquisition module is as follows: According to the equal-spacing principle, a number of vibration measurement points are set along the underground pipeline route. The sampling duration is set, and each vibration data generated by the construction machinery at each vibration measurement point within the sampling duration is obtained through a vibration sensor. The average value is calculated to obtain each vibration data. For each vibration data, the displacements at both ends of the pipeline under each vibration data are measured simultaneously, and the relative displacement data of the pipeline under each vibration data is obtained by taking the difference; this helps to predict the safety state of the pipeline under different vibration intensities and timely discover potential safety risks.

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

[0082] The model construction module is used to construct a pipeline risk assessment model with the 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 as follows: Determine the input variables of the model, including foundation pit soil data, pipeline data, groundwater level data, and vibration data. Among them, the foundation pit soil data includes the excavated depth of the foundation pit, the length and width of the foundation pit, and the ground surface settlement amount. The pipeline data includes the original length of the pipeline and the distances from both ends of the pipeline to the center point of the foundation pit. The groundwater level data includes the groundwater levels at each measurement point at each measurement time, and the vibration data includes each vibration data.

[0084] Taking the impact assessment result of the underground pipeline as the output variable of the model, including the safety factor and risk level of the pipeline, the risk strain value of the pipeline, the linear correlation degree between the groundwater level and the ground surface settlement amount, and the relative displacement data of the pipeline under each vibration data.

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

[0086] The specific operation method of the model construction module is as follows: normalize the input variables and output variables of the model to obtain the processed values of the input variables and output variables of the model. Form an input feature set and an output variable set according to the processed values of the input variables and output variables of the model. Assign weight factors to each piece of data in the output variable set. By accumulating the product of each piece of data in the output variable set and its corresponding weight factor, obtain the comprehensive risk assessment index of the pipeline. By matching with the corresponding comprehensive risk assessment index ranges of each set comprehensive risk level, obtain the comprehensive risk level of the pipeline. Normalization can avoid some variables dominating in model training due to overly large differences in variable value ranges, thus affecting the model's learning ability for other variables. Clearly distinguish the input and output parts of the model, and classify the processed relevant variables into the input feature set and the output variable set respectively, which helps to construct the structural framework of the model and determine the flow and use of data.

[0087] It should be noted that in a specific embodiment, when assigning weight factors to each piece of 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 local suspension of the pipeline, which may in turn lead to stress concentration and pose a serious threat to the structural integrity of the pipeline. Pipeline data reflects the material, structural characteristics of the pipeline itself and its risk tolerance under design conditions. Under external actions, it is prone to damage due to stress concentration. Changes in the groundwater level will change the physical and mechanical properties of the soil, such as causing soil softening, effective stress change, etc., and indirectly affect the stability of the pipeline. Vibration generated during construction will directly act on the pipeline, which may cause problems such as loosening of pipeline connectors and cracking of welds. Especially for pipelines made of some brittle materials, the impact of vibration is more significant. Therefore, the weight corresponding to soil data is the highest, and the weights corresponding to pipeline data and vibration data are the second highest.

[0088] It should be noted that the specific method of the normalization process is as follows: select the maximum and minimum values of each item from the input variables and output variables of the model, denoted as , and perform normalization through the formula to obtain the processed values of each item in the input variables and output variables of the model , represents the value of the th item of data in the input variables and output variables of the model, represents the number of the th item of data in the input variables and output variables of the model, .

[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 is established between the quantitative risk comprehensive assessment index and the qualitative comprehensive risk level, and the numerical result is converted into an intuitive risk level, such as low risk, medium risk, high risk, etc.

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

[0091] Please refer to Figure 3 As shown. In addition, the present invention provides an underground pipeline protection analysis method based on the foundation pit excavation state. The specific steps of this analysis method are as follows: A1. Generate a soil data measurement record form according to the foundation pit soil data, estimate the ground settlement amount from it, and then conduct a risk assessment on the pipeline bending stress and axial strain.

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

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

[0094] A4. Use the 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 ground settlement amount based on the elevation data of each measurement point in the excavated part of the foundation pit to judge whether there is a safety risk for the pipeline, measures the linear correlation degree between the groundwater level and the ground settlement amount according to the groundwater level at each measurement 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. By constructing a pipeline risk assessment model with input and output variables, a mapping relationship from multi-source data to risk assessment results is established, making the risk assessment more objective and accurate.

[0096] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention, and still be 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: The soil parameter analysis module generates soil data measurement record tables based on the foundation pit soil data, from which the surface settlement is estimated, and then the risk assessment of pipeline bending stress and axial strain is carried out; 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, calculate the soil excavation volume of the foundation pit, and estimate the surface settlement; S3. According to the uniformity of surface settlement Analyze pipeline bending stress , obtain the safety factor of the pipeline and determine the risk level of the pipeline; S31. Read the surface settlement of each excavation point , the average surface settlement is obtained by averaging , , Indicates The number of the excavation point, , 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, divide the surface settlement difference by the corresponding horizontal distance, and obtain the pipeline bending curvature of each 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 , ; S33. Get the set pipeline yield strength and divide it by Obtain the safety factor of the pipeline. If the safety factor of the pipeline is greater than or equal to the set safety factor threshold, it means that the risk level of the pipeline is low risk. Otherwise, it means that the risk level of the pipeline is high risk. S4. Analyze the axial strain of the pipeline according to the surface settlement at both ends of the pipeline, determine whether there is a safety risk in the pipeline according to the set threshold, and if so, calculate the risk strain value of the pipeline; The groundwater level analysis module obtains groundwater level data, correlates it with surface settlement, and measures the linear correlation between groundwater level and surface settlement; A vibration data acquisition module, which acquires each vibration data and the relative displacement data of the pipeline under each vibration data; The model building module uses foundation pit soil data, pipeline data, groundwater level data, and vibration data as input variables to build a pipeline risk assessment model and output the comprehensive risk level of the pipeline; The management database stores the empirical coefficients of soil types corresponding to 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 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 ,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.

3. The underground pipeline protection analysis system based on foundation pit excavation status according to claim 1 is characterized in that: 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.

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 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.

5. 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.

6. 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.

7. The underground pipeline protection analysis system based on foundation pit excavation status according to claim 6 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.

8. A method for analyzing underground pipeline protection based on foundation pit excavation status, executed by a system according to any one of claims 1 to 7, characterized in that: The specific steps of this 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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