Method and system for monitoring internal force of pile foundation of high-pile wharf using fiber Bragg grating strain sensor

Abstract

The present invention relates to the technical field of pile foundation monitoring, and specifically to a method and system for monitoring the internal force of a pile foundation of a high-pile wharf using a fiber grating strain sensor, comprising the following steps: S1, obtaining pile foundation bearing stress: obtaining pile foundation bearing stress parameters; S2, constructing a historical interval and a detection interval: establishing a detection interval with a width of a preset detection time; S3, determining a detection stress combination: determining a detection stress combination; S4, constructing a comparison interval and determining a comparison stress combination: determining a comparison stress combination; S5, determining a combination similarity value: determining a combination similarity value; S6, determining an effective interval: determining a combination with the largest combination similarity value; S7, judging whether the pile foundation bearing stress is greater than a threshold value: judging whether the pile foundation bearing stress is greater than a preset threshold stress. The present invention avoids structural damage caused by sudden overload or stress concentration, and improves the reliability and risk resistance of the pile foundation structure.

Description

Technical Field

[0001] The invention relates to the technical field of pile foundation monitoring, and in particular to a method and system for monitoring the internal force of a pile foundation of a high-pile wharf using a fiber grating strain sensor. Background Art

[0002] After the project is completed, it is affected by siltation. The additional earth pressure generated by the siltation acts on the pile foundation of the wharf, causing additional bending moment and deformation of the pile foundation, which may cause cracking and damage of the concrete pipe piles, seriously affecting the safety of the wharf structure. Therefore, it is necessary to monitor the internal forces (axial force, bending moment, shear force) of the foundation piles to understand the changes in the internal forces of the foundation piles under different load conditions and during the siltation process under the wharf, so as to ensure the safe use of the pile foundation structure.

[0003] At present, the internal force monitoring of pile foundations is often achieved through fiber optic Bragg grating strain sensors. The fiber optic Bragg grating strain sensors are installed on the pile foundations to measure the internal force of the pile foundations. When the internal force exceeds the set threshold, the corresponding prompt signal can be output to inform the staff of the specific situation in time. At this time, the staff can intervene in time to ensure the safety of the pile foundation structure.

[0004] In the above-mentioned related technologies, when monitoring the pile foundation structure, a prompt will only be given when the stress on the pile foundation exceeds the set threshold. At this time, the staff will be able to know that intervention is required. When the staff actually arrives at the location of the pile foundation for maintenance, there is already a certain lag, which causes the pile foundation structure to be relatively unstable for a period of time, making the overall monitoring effect of the pile foundation structure poor, and there is still room for improvement. Summary of the invention

[0005] The invention provides a method and a system for monitoring the internal force of a pile foundation of a high-pile wharf using a fiber grating strain sensor.

[0006] The method for monitoring the internal force of pile foundation of high-pile wharf by using fiber Bragg grating strain sensor comprises the following steps:

[0007] S1, obtaining pile foundation bearing stress: obtaining pile foundation bearing stress parameters detected by a fiber Bragg grating strain sensor installed on the pile foundation structure;

[0008] S2, constructing a historical interval and a detection interval: on a preset time axis, with the current time point as the rear end point, a historical interval with a width of a preset historical duration is established, and within the historical interval, with the current time point as the rear end point, a detection interval with a width of a preset detection duration is established, wherein the detection duration is less than the historical duration;

[0009] S3, determining the detection stress combination: within the detection interval, the pile foundation bearing stresses obtained in sequence are combined to determine the detection stress combination;

[0010] S4, constructing a comparison interval and determining a comparison stress combination: within the historical interval, randomly constructing a comparison interval with the same width as the detection interval, and determining a comparison stress combination according to the pile foundation bearing stress within the comparison interval;

[0011] S5, determining a combination similarity value: determining a combination similarity value based on a comparison between the detection stress combination and the comparison stress combination, reflecting the similarity between the two combinations;

[0012] S6, determining the effective interval: according to the preset sorting rule, determine the combination with the largest combination similarity value, and define the comparison interval corresponding to the combination as the effective interval, and then establish a detection interval with a width of the preset detection time length with the rear end point of the effective interval as the front end point;

[0013] S7, determine whether the pile foundation bearing stress is greater than the threshold: determine whether the pile foundation bearing stress is greater than the preset threshold stress within the detection interval. If the stress is not greater than the threshold stress, output a pile foundation safety signal. If the stress is greater than the threshold stress, define the alarm point based on the time point when the threshold stress first exceeds the standard, and determine the warning interval length based on the alarm point and the front end point of the detection interval, and output a pile foundation warning signal.

[0014] Optionally, the determining of the combined similarity value in S5 includes:

[0015] S51, overlapping and setting combinations and defining binding stresses: overlapping and setting the detection stress combination and the comparison stress combination, and defining the overlapping pile foundation bearing stresses in the combination as binding stresses;

[0016] S52, calculating the binding differential stress: performing differential calculation according to the binding stress to determine the binding differential stress, that is, calculating the difference in pile foundation bearing stress at different time points;

[0017] S53, calculating adjacent variable stresses: in the detection stress combination or the comparison stress combination, performing difference calculation according to the pile foundation bearing stresses at adjacent time points to determine adjacent variable stresses, and then performing difference calculation according to the adjacent variable stresses corresponding to the detection stress combination and the comparison stress combination to determine the variable difference stress;

[0018] S54, calculating mean differential stress: performing mean calculation on all binding differential stresses to determine binding mean stress, and similarly, performing mean calculation on all variable differential stresses to determine variable mean stress;

[0019] S55, calculating the combined similarity value: performing weighted calculation based on the bound mean stress, the variable mean stress and the preset calculation weight parameters, and finally determining the combined similarity value.

[0020] Optionally, the calculation formula of the combined similarity value in S55 is:

[0021] ;

[0022] in, is the combined similarity value, The parameters set by the staff for calculation, and To calculate the weight parameter, , is the bound mean stress, is the changing mean stress.

[0023] Optionally, the determining in S7 whether the pile foundation bearing stress is greater than a threshold value includes:

[0024] Determine the maximum similarity value interval: determine whether there are multiple comparison intervals with the same and maximum combination similarity values;

[0025] Counting alternative intervals and warning intervals: Counting is performed according to the alternative intervals to determine the alternative quantity, and counting is performed according to the warning intervals to determine the warning quantity. The alternative quantity is the total quantity of all determined alternative intervals, and the warning quantity is the total quantity of all determined warning intervals.

[0026] Calculate the warning ratio: The warning ratio is determined based on the number of warnings and the number of alternatives. The warning ratio is the ratio of the warning interval to the alternative interval, which is determined by dividing the number of warnings by the number of alternatives.

[0027] Determine the warning ratio and the benchmark ratio: Determine whether the warning ratio is greater than the preset benchmark ratio. The benchmark ratio is the minimum warning ratio that needs to be met when the alternative intervals set by the staff are all warning intervals.

[0028] Optionally, the determination of the maximum similarity value interval includes:

[0029] Define a valid interval: If there are no multiple comparison intervals with the same and largest combination similarity values, then define the comparison interval as a valid interval;

[0030] Define alternative intervals: If there are multiple comparison intervals with the same and largest combined similarity values, the comparison interval is defined as the alternative interval, and a detection interval is constructed based on each alternative interval. If there is a situation in the detection interval where the pile foundation bearing stress is greater than the threshold stress, the detection interval is defined as the warning interval.

[0031] Optionally, the judgment of the warning ratio and the benchmark ratio includes:

[0032] Output pile foundation safety signal: If the warning ratio is not greater than the benchmark ratio, the pile foundation safety signal is output, indicating that there is no abnormality in the pile foundation structure under the current external stress;

[0033] Output pile foundation warning signal: If the warning ratio is greater than the benchmark ratio, the warning interval is determined according to each warning interval, and the warning interval with the smallest value is output synchronously with the pile foundation warning signal.

[0034] Optionally, the determining whether the pile foundation bearing stress is greater than a threshold in S7 further includes:

[0035] Determine whether the maximum combined similarity value is greater than the required value: Determine whether the combined similarity value with the largest value is greater than the preset required similarity value. If the combined similarity value with the largest value is greater than the required similarity value, determine the effective interval or the alternative interval. If the combined similarity value with the largest value is not greater than the required similarity value, calculate the difference between the detection change stress and the comparison change stress.

[0036] Calculate mean stress: calculate the test mean stress according to the pile foundation bearing stress in the test stress combination, and calculate the comparative mean stress according to the pile foundation bearing stress in the comparative stress combination;

[0037] Define equivalent intervals and calculate point-level change stress: define the comparison intervals where the comparison change stress is consistent with the detection change stress and the comparison mean stress is consistent with the detection mean stress as the equivalent interval, construct the detection interval based on the rear endpoint of the equivalent interval, calculate the difference between the pile foundation bearing stress in the detection interval and the pile foundation bearing stress at the rear endpoint of the equivalent interval, and determine the point-level change stress;

[0038] Determine equivalent variable stress: determine the variable stress at the point with the largest value according to the sorting rules, and define the variable stress at the point as the equivalent variable stress;

[0039] Calculate equivalent mean stress and predict maximum stress: Calculate equivalent mean stress based on all equivalent variable stresses, and calculate and predict the maximum stress by adding the pile foundation bearing stress at the current time point to the equivalent mean stress;

[0040] Output fixed time length and pile foundation warning signal: When the predicted maximum stress is greater than the threshold stress, output fixed time length and pile foundation warning signal.

[0041] The fiber Bragg grating strain sensor high-pile wharf pile foundation internal force monitoring system is used to implement the above-mentioned fiber Bragg grating strain sensor high-pile wharf pile foundation internal force monitoring method, including the following modules:

[0042] Fiber Bragg grating strain sensor module: detects the bearing stress of the pile foundation structure and obtains stress data in real time;

[0043] Data processing module: receives stress data from the fiber Bragg grating strain sensor, constructs the historical interval and the detection interval, and determines the detection stress combination;

[0044] Similarity value calculation module: calculates the combination similarity value based on the detection stress combination and the comparison stress combination, and determines the effective interval based on the similarity;

[0045] Early warning judgment module: judge whether the pile foundation bearing stress exceeds the preset threshold stress within the detection range, and output a pile foundation early warning signal if it exceeds.

[0046] Beneficial effects of the present invention:

[0047] The present invention, through monitoring the bearing stress of the pile foundation structure based on the fiber Bragg grating strain sensor, can obtain the stress data of the current pile foundation in real time and compare it with the historical data. By analyzing the bearing stress data of the pile foundation in the detection interval and the historical interval, combined with the calculation method of the combined similarity value, the present invention can effectively predict the stress changes that may occur in the future and judge in advance whether there is a risk of exceeding the preset threshold. In this way, the staff can discover potential risks in time and take appropriate measures, thereby improving the safety of the pile foundation structure, avoiding structural damage due to sudden overload or stress concentration, and improving the reliability and risk resistance of the pile foundation structure.

[0048] The present invention considers the actual processing time of the staff in the process of setting the threshold stress, reasonably analyzes the time required for maintenance, and sets the threshold stress that matches the actual operation requirements. It can not only ensure that the safety assessment of the pile foundation structure is more scientific and reasonable, but also can send a warning signal to the staff before the overload stress occurs, so that they can handle it in advance and avoid delaying the maintenance opportunity. In practical applications, it has higher emergency response efficiency and reduces the safety hazards and economic losses that may be caused by delayed response. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0050] Figure 1 A schematic diagram of a monitoring method flow chart of an embodiment of the present invention;

[0051] Figure 2 Schematic diagram of system function modules according to an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art may also adopt other alternatives to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0053] It should be noted that the references to "one embodiment", "embodiment", "exemplary embodiments", "some embodiments" and the like in the specification indicate that the embodiments described may include specific features, structures or characteristics, but not every embodiment may include the specific features, structures or characteristics. In addition, when a specific feature, structure or characteristic is described in conjunction with an embodiment, it should be within the knowledge of a person skilled in the art to implement such feature, structure or characteristic in conjunction with other embodiments (whether or not explicitly described).

[0054] In general, a term can be understood, at least in part, from its use in context. For example, depending, at least in part, on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in the singular sense, or can be used to describe a combination of features, structures, or characteristics in the plural sense. Additionally, the term "based on" can be understood as not necessarily intended to convey an exclusive set of factors, but can instead, depending, at least in part, on the context, allow for the presence of other factors that are not necessarily explicitly described.

[0055] like Figure 1 As shown, the fiber Bragg grating strain sensor high-pile wharf pile foundation internal force monitoring method comprises the following steps:

[0056] Step S100: Obtaining pile foundation bearing stress.

[0057] The pile foundation bearing stress is the stress parameter detected and obtained by the fiber grating strain sensor installed on the pile foundation structure.

[0058] Step S101: On a preset time axis, a historical interval with the current time point as the rear end point and a width of a preset historical duration is established, and a detection interval with the current time point as the rear end point and a width of a preset detection duration is established in the historical interval, wherein the detection duration is less than the historical duration.

[0059] The time axis is a coordinate axis formed by the combination of various time points. The coordinate axis points from the time points that have passed to the time points that have not yet arrived, and the time points that have passed are on the left side of the time axis, and the left side is defined as the front of the time axis; the historical duration and the detection duration are fixed durations set by the staff, among which the historical duration should be much larger than the detection duration, for example, the historical duration is three years and the detection duration is one hour; by constructing historical intervals and detection intervals, data at different time points can be acquired and analyzed.

[0060] Step S102: Combining the pile foundation bearing stresses obtained successively in the detection interval to determine a detection stress combination.

[0061] The detection stress combination is a combination of pile foundation bearing stresses obtained in the detection interval sorted according to the time sequence of acquisition.

[0062] Step S103: randomly constructing a comparison interval with the same width as the detection interval in the historical interval, and determining a comparison stress combination according to the pile foundation bearing stress in the comparison interval.

[0063] Constructing the comparison interval can determine the changes in the pile foundation structure under historical conditions, which is convenient for subsequent analysis; the comparison stress combination is a combination of the pile foundation bearing stresses obtained in the comparison interval sorted according to the order of acquisition time.

[0064] Step S104: Determine a combination similarity value by comparing the detection stress combination and the comparison stress combination.

[0065] The combined similarity value is a value reflecting the overall similarity of the data in the detection stress combination and the comparison stress combination. The larger the value, the similar the external stresses to which the pile foundation structure is subjected at different time points. The calculation method of the combined similarity value can refer to steps S200 to S204.

[0066] Step S105: Determine the combined similarity value with the largest value according to the preset sorting rule, define the comparison interval corresponding to the combined similarity value as the effective interval, and establish a detection interval with a width of the preset detection time length with the rear end point of the effective interval as the front end point.

[0067] The sorting rule is a method set by the staff to sort the values, such as the bubble method. The sorting rule can be used to determine the combined similarity value with the largest value, which means that the external stress on the pile foundation in the current corresponding comparison interval is similar to the current one. At this time, the interval is defined as a valid interval to distinguish different comparison intervals, which is convenient for subsequent analysis; the detection time is the time set by the staff to obtain data for a subsequent period of time in the comparison interval, such as 5 hours. By establishing a detection interval, data within the detection time can be obtained, which is convenient for subsequent analysis.

[0068] Step S106: determining whether there is a situation in the detection interval where the pile foundation bearing stress is greater than a preset threshold stress.

[0069] The threshold stress is the minimum pile foundation bearing stress set by the staff to determine that the pile foundation structure is subject to a significant external impact. The purpose of the judgment is to find out whether there is a situation in which the pile foundation structure is affected in the detection interval.

[0070] Step S1061: If there is no situation in the detection interval where the pile foundation bearing stress is greater than the threshold stress, a pile foundation safety signal is output.

[0071] When there is no situation in the detection interval where the pile foundation bearing stress is greater than the threshold stress, it means that there is no situation in the detection interval where the pile foundation structure is affected, that is, under the external stress corresponding to the effective interval, the pile foundation structure can be used normally. Therefore, since the external stress to which the current monitoring interval is subjected is similar to that of the effective interval, it can be determined that the pile foundation can be used relatively safely within the subsequent detection time at the current time point. Therefore, a pile foundation safety signal can be output to identify the situation.

[0072] Step S1062: If there is a situation in the detection interval where the pile foundation bearing stress is greater than the threshold stress, the time point when the pile foundation bearing stress first appears to be greater than the threshold stress is defined as the alarm point, and the warning interval is determined based on the alarm point and the front end point of the detection interval, and the warning interval and the preset pile foundation warning signal are output synchronously.

[0073] When the pile foundation bearing stress in the detection interval is greater than the threshold stress, it means that the pile foundation structure is affected in the detection interval, that is, under the external stress corresponding to the effective interval, the pile foundation structure is affected by the outside, and there may be a more dangerous situation. Therefore, by determining the first time point and defining it as the alarm point, it is possible to determine the time interval in which the abnormality may occur later, that is, the warning interval. By synchronously outputting the warning interval and the pile foundation warning signal, the staff can pay attention to the situation in time, which is convenient for the staff to deploy manual intervention tasks in advance; the pile foundation warning signal only serves as a reminder.

[0074] The steps of comparing the test stress combination and the comparison stress combination to determine the combination similarity value include:

[0075] Step S200: Overlapping the detection stress combination and the comparison stress combination to define the overlapping pile foundation bearing stresses in different combinations as binding stresses.

[0076] Overlapping means aligning the detection stress combination and the comparison stress combination head to tail. At this time, each data in the two combinations will overlap with the data of the other combination, which is defined as binding stress to distinguish different parameters and facilitate subsequent analysis.

[0077] Step S201: performing difference calculation based on mutually determined binding stresses to determine a binding difference stress.

[0078] The bind difference stress is the difference between two mutually determined bind stresses, which is an absolute value.

[0079] Step S202: performing difference calculation according to pile foundation bearing stresses determined at adjacent time points in the same combination to determine adjacent variable stresses, and performing difference calculation according to corresponding adjacent variable stresses determined in the detection stress combination and the comparison stress combination to determine variable differential stresses.

[0080] The adjacent variable stress is the difference between the pile foundation bearing stresses obtained at adjacent time points in the same combination, and the difference is an absolute value. The variable difference stress is the difference between the adjacent variable stresses determined by the pile foundation bearing stresses at the same position in the two combinations, and the difference is also an absolute value.

[0081] Step S203: performing mean calculation based on all binding differential stresses to determine binding mean stress, and performing mean calculation based on all changing differential stresses to determine changing mean stress.

[0082] The bound mean stress is the average of all bound differential stresses, and the variable mean stress is the average of all variable differential stresses.

[0083] Step S204: performing calculations based on the bound mean stress, the variable mean stress, and preset calculation weight parameters to determine a combined similarity value.

[0084] The calculation weight parameter is the fixed value parameter set by the staff, and the calculation formula for the combined similarity value is: ,in is the combined similarity value, The parameters set by the staff for calculation, and To calculate the weight parameter, , is the bound mean stress, is the changing mean stress.

[0085] After the combined similarity value is determined, the method for monitoring the internal force of the pile foundation structure of the high-pile wharf based on the fiber Bragg grating strain sensor also includes:

[0086] Step S300: Determine whether there are multiple comparison intervals with the same and maximum combined similarity values.

[0087] The purpose of the judgment is to find out whether there are multiple comparison intervals that meet the requirements.

[0088] Step S3001: If there are not multiple comparison intervals with the same and maximum combined similarity values, the comparison interval is defined as a valid interval.

[0089] When there are not multiple comparison intervals with the same and largest combined similarity values, it means that there is only one comparison interval that meets the requirements, and it can be defined as a valid interval.

[0090] Step S3002: If there are multiple comparison intervals with the same and largest combined similarity values, the comparison interval is defined as an alternative interval, and a detection interval is constructed based on each alternative interval, and the detection interval where the pile foundation bearing stress is greater than the threshold stress is defined as a warning interval.

[0091] When there are multiple comparison intervals with the same and largest combined similarity values, it means that there are multiple comparison intervals that meet the requirements. At this time, further analysis is needed to define them as alternative intervals to distinguish different comparison intervals; at the same time, define warning intervals to distinguish the intervals that need warnings, which is convenient for subsequent analysis.

[0092] Step S301: Counting is performed according to the candidate interval to determine the candidate quantity, and counting is performed according to the warning interval to determine the warning quantity.

[0093] The number of alternatives is the total number of all determined alternative intervals, and the number of warnings is the total number of all determined warning intervals.

[0094] Step S302: Calculate the warning ratio based on the number of warnings and the number of alternatives.

[0095] The warning ratio is the ratio of the warning interval to the alternative interval, which is determined by dividing the number of warnings by the number of alternatives.

[0096] Step S303: Determine whether the warning ratio is greater than a preset reference ratio.

[0097] The benchmark ratio is the minimum warning ratio set by the staff to determine that most of the alternative intervals are warning intervals. The purpose of the judgment is to find out whether there is a high probability of a warning being required in the future under the current external stress changes.

[0098] Step S3031: If the warning ratio is not greater than the reference ratio, a pile foundation safety signal is output.

[0099] When the warning ratio is not greater than the benchmark ratio, it means that under the current external stress conditions, there is a high probability that a situation requiring a warning will not occur. At this time, the pile foundation safety signal can be output for identification.

[0100] Step S3032: If the warning ratio is greater than the reference ratio, the warning interval duration is determined according to each warning interval, and the warning interval duration with the smallest value is output synchronously with the pile foundation warning signal.

[0101] When the warning ratio is greater than the benchmark ratio, it means that under the current external stress, there is a high probability that a pile foundation warning signal will be output in the future. At this time, the warning interval with the smallest value can be output synchronously with the pile foundation warning signal to achieve effective analysis of pile foundation structure abnormalities.

[0102] After the combined similarity value is determined, the method for monitoring the internal force of the pile foundation structure of the high-pile wharf based on the fiber Bragg grating strain sensor also includes:

[0103] Step S400: Determine whether the combined similarity value with the largest value is greater than a preset demand similarity value.

[0104] The required similarity value is the minimum combined similarity value that needs to be met when the stress change conditions are relatively similar, set by the staff. The purpose of the judgment is to find out whether there is a comparison interval with relatively similar stress change conditions.

[0105] Step S4001: If the combined similarity value with the largest value is greater than the required similarity value, a valid interval or an alternative interval is determined.

[0106] When the combined similarity value with the largest value is greater than the required similarity value, it indicates that there is a comparison interval with relatively similar stress changes. In this case, the subsequent analysis can be carried out normally.

[0107] Step S4002: If the combined similarity value with the largest value is not greater than the required similarity value, a difference calculation is performed based on the pile foundation bearing stresses at the front end and the rear end of the detection stress combination to determine the detection change stress, and a difference calculation is performed based on the pile foundation bearing stresses at the front end and the rear end of the comparison stress combination to determine the comparison change stress.

[0108] When the combined similarity value with the largest value is not greater than the required similarity value, it means that there is no comparison interval in which the stress change is similar to the stress change at the current time point. Further analysis is required at this time. The detected change stress is the overall change value of the external stress in the detection interval, which is determined by subtracting the pile foundation bearing stress at the end of the detection stress combination from the pile foundation bearing stress at the front end of the detection stress combination. Similarly, the comparative change stress in the comparison interval can be determined to facilitate subsequent analysis.

[0109] Step S401: performing mean calculation according to the pile foundation bearing stress in the detection stress combination to determine the detection mean stress, and performing mean calculation according to the pile foundation bearing stress in the comparison stress combination to determine the comparison mean stress.

[0110] The detection mean stress is the average value of the pile foundation bearing stress in the detection stress combination, and the comparison mean stress is the average value of the pile foundation bearing stress in the comparison stress combination.

[0111] Step S402: define the comparison interval in which the comparison change stress is consistent with the detection change stress and the comparison mean stress is consistent with the detection mean stress as an equivalent interval, and construct a detection interval based on the rear endpoint of the equivalent interval, and perform a difference calculation based on the pile foundation bearing stress in the detection interval and the pile foundation bearing stress determined at the rear endpoint of the equivalent interval to determine the point change stress.

[0112] When the comparison change stress is consistent with the detection change stress and the comparison mean stress is consistent with the detection mean stress, it means that the changes in the two intervals are similar. At this time, they are defined as equivalent intervals to distinguish different comparison intervals for subsequent analysis. The point change stress is the stress value obtained by subtracting the pile foundation bearing stress determined at the end point of the equivalent interval from the pile foundation bearing stress in the detection interval.

[0113] Step S403: determining the point-position change stress with the largest value according to the sorting rule, and defining the point-position change stress as the equivalent change stress.

[0114] The sorting rules can be used to determine the point-by-point stress change with the largest value, that is, the point-by-point stress change has the maximum change value that will occur. At this time, it is defined as an equivalent stress change to distinguish stress changes at different points, which is convenient for subsequent analysis.

[0115] Step S404: performing mean calculation based on all equivalent variable stresses to determine the equivalent mean stress, and performing calculation based on the pile foundation bearing stress determined at the current time point and the equivalent mean stress to determine the predicted maximum stress.

[0116] The equivalent mean stress is the average value of all equivalent variable stresses. The maximum external stress that will occur in the future under theoretical circumstances can be determined by adding the pile foundation bearing stress determined at the current time point to the equivalent mean stress, that is, the predicted maximum stress.

[0117] Step S405: when the predicted maximum stress is greater than the threshold stress, output a preset fixed time length and a pile foundation warning signal.

[0118] When the predicted maximum stress is greater than the threshold stress, it means that there is a high probability that a warning will be required. At this time, the fixed time length and the pile foundation warning signal can be output simultaneously, where the fixed time length is the fixed value time length set by the staff.

[0119] After the equivalent change stress is determined, the method for monitoring the stress of the pile foundation structure of the high-pile wharf based on the fiber grating strain sensor also includes:

[0120] Step S500: performing difference calculation based on the equivalent variable stress with the largest value and the equivalent variable stress with the smallest value to determine the equivalent separation stress.

[0121] The equivalent phase stress is the value obtained by subtracting the equivalent variable stress with the smallest value from the equivalent variable stress with the largest value.

[0122] Step S501: determining whether the equivalent separation stress is greater than a preset reference separation stress.

[0123] The reference separation stress is the maximum equivalent separation stress allowed to be met when the equivalent change stress is not much different, as set by the staff. The purpose of the judgment is to find out whether the need for early warning can be determined through the currently determined equivalent change stress.

[0124] Step S5011: If the equivalent separation stress is not greater than the reference separation stress, then determine the equivalent mean stress according to all equivalent variable stresses.

[0125] When the equivalent phase separation stress is not greater than the reference phase separation stress, it means that the determined equivalent change stress can be used for early warning situation analysis. At this time, the equivalent mean stress can be determined normally.

[0126] Step S5012: If the equivalent separation stress is greater than the reference separation stress, the alarm point of the previous pile foundation warning signal output is obtained, and the stable separation time is determined according to the alarm point and the current time point.

[0127] When the equivalent interval stress is greater than the benchmark interval stress, it means that the equivalent variable stress determined previously is quite different, and it is impossible to determine the subsequent situation that will occur under the current circumstances by analyzing the equivalent variable stress. Further analysis is needed at this time; the stable interval time is the time interval from the last output of the pile foundation warning signal to the current time point.

[0128] Step S502: Determine whether the stable interval time is greater than a preset reasonable interval time.

[0129] The reasonable interval time is the maximum stable interval time set by the staff to determine that the pile foundation structure is unlikely to be damaged. The purpose of the judgment is to find out whether there is a possibility of abnormality in the pile foundation structure at present.

[0130] Step S5021: If the stable interval time is not greater than the reasonable interval time, a pile foundation safety signal is output.

[0131] When the stable interval time is not greater than the reasonable interval time, it means that there is basically no abnormality in the pile foundation structure, and at this time, the pile foundation safety signal can be output.

[0132] Step S5022: If the stable interval time is greater than the reasonable interval time, a fixed time and a pile foundation warning signal are output.

[0133] When the stable interval time is longer than the reasonable interval time, it indicates that there may be an abnormality in the pile foundation structure. At this time, the corresponding pile foundation warning signal can be output.

[0134] Also included is a step of determining a threshold stress, the step comprising:

[0135] Step S600: Acquire the position of the detected pile foundation.

[0136] The detection pile foundation position, that is, the position where the pile foundation is installed, can be obtained by locating the installation position of the fiber grating strain sensor.

[0137] Step S601: Determine the theoretical required time corresponding to the detection of the pile foundation position according to a preset time matching relationship.

[0138] The theoretical required time is the theoretical time required for the staff to reach the inspection pile foundation location for maintenance and inspection. Different inspection pile foundation locations are at different distances from the staff, and the theoretical required time required is also different. Therefore, the time matching relationship between the two can be entered and stored in advance by the staff according to the actual location conditions.

[0139] Step S602: determining the number of waiting maintenance tasks in a preset task database, and determining a theoretical waiting time corresponding to the number of waiting maintenance tasks according to a preset number matching relationship.

[0140] The task database is a database that records pile foundations that have output pile foundation warning signals and require staff to arrive at the site for repair and treatment. The repair order of the pile foundations in the database is determined according to the output time sequence of the pile foundation warning signals; the repair waiting number is the number of pile foundations that need to be repaired in the task database; the theoretical waiting time is the time required in theory to repair the pile foundation structure with the repair waiting number. Different repair waiting numbers correspond to different theoretical waiting times, and the quantity matching relationship between the two is determined in advance by the staff.

[0141] Step S603: performing a sum calculation based on the theoretical demand duration and the theoretical waiting duration to determine the overall demand duration.

[0142] The overall required time is the total time theoretically required from the time when the pile foundation warning signal is output to the time when the staff arrives at the pile foundation structure for maintenance and treatment, which is determined by adding the theoretical required time to the theoretical waiting time.

[0143] Step S604: determining the adjustment stress corresponding to the overall required duration according to the preset adjustment matching relationship, and performing a difference calculation according to the preset fixed stress and the adjustment stress to determine the threshold stress.

[0144] Fixed stress is a fixed parameter value used to determine the threshold stress, and adjusted stress is a parameter value used to adjust the fixed stress. The longer the overall required time is, the longer the waiting time for pile foundation maintenance is. At this time, the corresponding adjusted stress is also greater, so that the corresponding threshold stress can be smaller, thereby being able to output the pile foundation early warning signal faster so that the staff can handle it in time; the adjustment matching relationship is set in advance by the staff according to the actual situation.

[0145] like Figure 2 As shown, the fiber Bragg grating strain sensor high-pile wharf pile foundation internal force monitoring system is used to implement the above-mentioned fiber Bragg grating strain sensor high-pile wharf pile foundation internal force monitoring method, including the following modules:

[0146] Fiber Bragg grating strain sensor module: detects the bearing stress of the pile foundation structure and obtains stress data in real time;

[0147] Data processing module: receives stress data from the fiber Bragg grating strain sensor, constructs the historical interval and the detection interval, and determines the detection stress combination;

[0148] Similarity value calculation module: calculates the combination similarity value based on the detection stress combination and the comparison stress combination, and determines the effective interval based on the similarity;

[0149] Early warning judgment module: judge whether the pile foundation bearing stress exceeds the preset threshold stress within the detection range, and output a pile foundation early warning signal if it exceeds.

[0150] The present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention. In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without the description of these details. In addition, in order to avoid unnecessary confusion about the essence of the present invention, well-known methods, processes, procedures, components and circuits are not described in detail.

[0151] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for monitoring internal forces of pile foundations of high-pile docks using a fiber Bragg grating strain sensor, characterized in that: The following steps are involved: S1, obtaining pile foundation bearing stress: obtaining pile foundation bearing stress parameters detected by a fiber Bragg grating strain sensor installed on the pile foundation structure; S2, constructing a historical interval and a detection interval: on a preset time axis, with the current time point as the rear end point, a historical interval with a width of a preset historical duration is established, and within the historical interval, with the current time point as the rear end point, a detection interval with a width of a preset detection duration is established, wherein the detection duration is less than the historical duration; S3, determining the detection stress combination: within the detection interval, the pile foundation bearing stresses obtained in sequence are combined to determine the detection stress combination; S4, constructing a comparison interval and determining a comparison stress combination: within the historical interval, randomly constructing a comparison interval with the same width as the detection interval, and determining a comparison stress combination according to the pile foundation bearing stress within the comparison interval; S5, determining a combination similarity value: determining a combination similarity value based on a comparison between the detection stress combination and the comparison stress combination, reflecting the similarity between the two combinations; S6, determining the effective interval: according to the preset sorting rule, determine the combination with the largest combination similarity value, and define the comparison interval corresponding to the combination as the effective interval, and then establish a detection interval with a width of the preset detection time length with the rear end point of the effective interval as the front end point; S7, judging whether the pile foundation bearing stress is greater than a threshold value: judging whether the pile foundation bearing stress is greater than a preset threshold stress within the detection interval, if the stress is not greater than the threshold stress, outputting a pile foundation safety signal, if the stress is greater than the threshold stress, defining the time point at which the threshold stress first exceeds the standard as an alarm point, and determining the warning interval duration according to the alarm point and the front end point of the detection interval, and outputting a pile foundation warning signal; The determining of the combined similarity value in S5 includes: S51, overlapping and setting combinations and defining binding stresses: overlapping and setting the detection stress combination and the comparison stress combination, and defining the overlapping pile foundation bearing stresses in the combination as binding stresses; S52, calculating the binding differential stress: performing differential calculation according to the binding stress to determine the binding differential stress, that is, calculating the difference in pile foundation bearing stress at different time points; S53, calculating adjacent variable stresses: in the detection stress combination or the comparison stress combination, performing difference calculation according to the pile foundation bearing stresses at adjacent time points to determine adjacent variable stresses, and then performing difference calculation according to the adjacent variable stresses corresponding to the detection stress combination and the comparison stress combination to determine the variable difference stress; S54, calculating mean differential stress: performing mean calculation on all binding differential stresses to determine binding mean stress, and similarly, performing mean calculation on all variable differential stresses to determine variable mean stress; S55, calculating the combined similarity value: performing weighted calculation based on the bound mean stress, the variable mean stress and the preset calculation weight parameters, and finally determining the combined similarity value.

2. The fiber Bragg grating strain sensor high-pile dock pile foundation internal force monitoring method according to claim 1 is characterized in that: The calculation formula of the combined similarity value in S55 is: ； in, is the combined similarity value, The parameters set by the staff for calculation, and To calculate the weight parameter, , is the bound mean stress, is the changing mean stress.

3. The method for monitoring internal force of pile foundation of high-pile dock using fiber Bragg grating strain sensor according to claim 2 is characterized in that: The determination in S7 whether the pile foundation bearing stress is greater than a threshold value includes: Determine the maximum similarity value interval: determine whether there are multiple comparison intervals with the same and maximum combination similarity values; Counting alternative intervals and warning intervals: Counting is performed according to the alternative intervals to determine the alternative quantity, and counting is performed according to the warning intervals to determine the warning quantity. The alternative quantity is the total quantity of all determined alternative intervals, and the warning quantity is the total quantity of all determined warning intervals. Calculate the warning ratio: The warning ratio is determined based on the number of warnings and the number of alternatives. The warning ratio is the ratio of the warning interval to the alternative interval, which is determined by dividing the number of warnings by the number of alternatives. Determine the warning ratio and the benchmark ratio: Determine whether the warning ratio is greater than the preset benchmark ratio. The benchmark ratio is the minimum warning ratio that needs to be met when the alternative intervals set by the staff are all warning intervals.

4. The method for monitoring internal force of pile foundation of high-pile dock using fiber Bragg grating strain sensor according to claim 3 is characterized in that: The maximum similarity value interval is determined as follows: Define a valid interval: If there are no multiple comparison intervals with the same and largest combination similarity values, then define the comparison interval as a valid interval; Define alternative intervals: If there are multiple comparison intervals with the same and largest combined similarity values, the comparison interval is defined as the alternative interval, and a detection interval is constructed based on each alternative interval. If there is a situation in the detection interval where the pile foundation bearing stress is greater than the threshold stress, the detection interval is defined as the warning interval.

5. The method for monitoring internal force of pile foundation of high-pile dock using fiber Bragg grating strain sensor according to claim 4 is characterized in that: The judgment and warning ratio and the benchmark ratio include: Output pile foundation safety signal: If the warning ratio is not greater than the benchmark ratio, the pile foundation safety signal is output, indicating that there is no abnormality in the pile foundation structure under the current external stress; Output pile foundation warning signal: If the warning ratio is greater than the benchmark ratio, the warning interval is determined according to each warning interval, and the warning interval with the smallest value is output synchronously with the pile foundation warning signal.

6. The method for monitoring internal force of pile foundation of high-pile dock using fiber Bragg grating strain sensor according to claim 5, characterized in that: The determining whether the pile foundation bearing stress is greater than a threshold value in S7 further includes: Determine whether the maximum combined similarity value is greater than the required value: Determine whether the combined similarity value with the largest value is greater than the preset required similarity value. If the combined similarity value with the largest value is greater than the required similarity value, determine the effective interval or the alternative interval. If the combined similarity value with the largest value is not greater than the required similarity value, calculate the difference between the detection change stress and the comparison change stress. Calculate mean stress: calculate the test mean stress according to the pile foundation bearing stress in the test stress combination, and calculate the comparative mean stress according to the pile foundation bearing stress in the comparative stress combination; Define equivalent intervals and calculate point-level change stress: define the comparison intervals where the comparison change stress is consistent with the detection change stress and the comparison mean stress is consistent with the detection mean stress as the equivalent interval, construct the detection interval based on the rear endpoint of the equivalent interval, calculate the difference between the pile foundation bearing stress in the detection interval and the pile foundation bearing stress at the rear endpoint of the equivalent interval, and determine the point-level change stress; Determine equivalent variable stress: determine the variable stress at the point with the largest value according to the sorting rules, and define the variable stress at the point as the equivalent variable stress; Calculate equivalent mean stress and predict maximum stress: Calculate equivalent mean stress based on all equivalent variable stresses, and calculate and predict the maximum stress by adding the pile foundation bearing stress at the current time point to the equivalent mean stress; Output fixed time length and pile foundation warning signal: When the predicted maximum stress is greater than the threshold stress, output fixed time length and pile foundation warning signal.

7. A fiber Bragg grating strain sensor high-pile dock pile foundation internal force monitoring system, used to implement a fiber Bragg grating strain sensor high-pile dock pile foundation internal force monitoring method as claimed in any one of claims 1 to 6, characterized in that: Includes the following modules: Fiber Bragg grating strain sensor module: detects the bearing stress of the pile foundation structure and obtains stress data in real time; Data processing module: receives stress data from the fiber Bragg grating strain sensor, constructs the historical interval and the detection interval, and determines the detection stress combination; Similarity value calculation module: calculates the combination similarity value based on the detection stress combination and the comparison stress combination, and determines the effective interval based on the similarity; Early warning judgment module: judge whether the pile foundation bearing stress exceeds the preset threshold stress within the detection range, and output a pile foundation early warning signal if it exceeds.

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