A displacement monitoring system for deepwater bottomless double-walled steel cofferdam construction

Abstract

The invention belongs to the technical field of steel cofferdam displacement monitoring, and specifically discloses a deep-water bottomless double-wall steel cofferdam construction displacement monitoring system. The system performs multi-source displacement monitoring on a lowered cofferdam section during a trial monitoring period, and simultaneously performs water level and flow rate monitoring, and uses mutation analysis of displacement to identify environmental impact monitoring sources, so that in subsequent displacement monitoring, the monitoring results of water level and flow rate are combined to select effective monitoring sources for precise displacement monitoring. This process realizes effect verification before displacement monitoring is implemented, and ensures the accuracy of displacement data to the maximum extent. At the same time, when using the displacement monitoring results for analysis, the displacement guidance analysis of the lowered steel cofferdam section is performed by identifying the displacement monitoring points, and combining the layout positions and displacement directions of these monitoring points. This process realizes the in-depth utilization of displacement monitoring data, can provide targeted guidance for displacement correction, and is conducive to improving correction efficiency and correction effect.

Description

Technical Field

[0001] The invention belongs to the technical field of steel cofferdam displacement monitoring, and specifically discloses a deep-water bottom-less double-wall steel cofferdam construction displacement monitoring system. Background Art

[0002] In modern water conservancy projects, bridge construction and marine engineering, foundation construction in deepwater environments faces many challenges such as high construction difficulty and high cost. Traditional methods such as earth cofferdams are difficult to meet these requirements. Against this background, deepwater bottomless double-walled steel cofferdams came into being. Double-walled steel cofferdams are a special structure consisting of two layers of steel plates, with air or lightweight materials filled in the middle. This design increases the overall rigidity and stability of the cofferdam, allowing it to maintain a good shape and position in deepwater environments. In addition, double-walled steel cofferdams can be prefabricated and quickly assembled on site, with fast construction speed, strong adaptability, and can be adjusted according to different water depths and geological conditions. Therefore, double-walled steel cofferdams have become an essential tool for foundation construction in deepwater environments.

[0003] Since the construction of double-walled steel cofferdams is done in sections, the positional deviation of the lowered section of each steel cofferdam during the deep-water lowering process will directly affect the lowering stability of the subsequent sections. This is because the lowered steel cofferdam sections are easily offset by the underwater geological conditions and water flow impact in the underwater environment. Therefore, in order to ensure the stability of the entire steel cofferdam structure and construction safety, it is necessary to monitor the displacement of the lowered sections during the steel cofferdam construction process.

[0004] The Chinese invention patent with the publication number CN118911173A for the existing technology of steel cofferdam displacement monitoring discloses a deep-water double-walled steel cofferdam and its sinking construction method. In this scheme, after the blocks of the double-walled steel cofferdam are hoisted to the designated position and assembled and the sinking operation is completed, the cofferdam deflection is monitored in real time, wherein the monitoring of the cofferdam deflection uses inclinometers, gyroscopes, etc. to realize the monitoring of the inclination angle and rotation of the cofferdam, and then the double-walled steel cofferdam is corrected by using the centralized excavation method and the backfilling sand and gravel method according to the monitoring results. The monitoring of the cofferdam deflection in this scheme ignores the sensitivity of the displacement monitoring equipment in the underwater environment, especially in the deep water environment. The wireless signal transmission of some displacement monitoring equipment is easily interfered, especially in the case of water level fluctuations and flow velocity fluctuations. Such interference will aggravate the instability of data transmission, thereby affecting the accuracy of the monitoring results. If the effectiveness of the displacement monitoring equipment is not verified and it is directly used for displacement monitoring, it is easy to lead to invalid monitoring, and thus it is impossible to provide reliable data support for correction.

[0005] There is also a Chinese invention patent with publication number CN116537271A in the prior art that discloses a method for monitoring and measuring a deep foundation pit. By arranging monitoring points at the four corners of the cofferdam, the internal support and other positions to monitor the displacement data of each monitoring point, the monitoring data during the construction process can be timely and accurately grasped, and by analyzing and comparing the actual monitoring data with the theoretical prediction value, the deformation amount of the foundation pit can be effectively controlled during the construction process, and accurate monitoring and measurement of the foundation pit can be achieved. When performing deformation analysis based on the displacement data of the monitoring points, this invention only focuses on the deformation amount but does not reveal the deformation direction and distribution characteristics, resulting in an overly superficial deformation analysis, which makes the correction measures lack pertinence and cannot effectively solve practical problems, thereby invisibly increasing the time cost of the correction operation. Summary of the invention

[0006] In order to solve the above technical problems or at least partially solve the above technical problems, the present application provides a deep-water bottomless double-wall steel cofferdam construction displacement monitoring system, which aims to optimize the two aspects of displacement monitoring equipment selection and displacement monitoring data use to achieve effective monitoring of the displacement of the lowered steel cofferdam.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A deep-water bottomless double-wall steel cofferdam construction displacement monitoring system, comprising the following modules: a monitoring point layout module, used to layout monitoring points corresponding to corner points and internal support connection points of the lowered steel cofferdam section during the process of lowering the steel cofferdam in deep water.

[0008] The displacement test monitoring module is used to use multiple monitoring sources to perform displacement monitoring at each monitoring point during the selected test monitoring period to form a displacement time series of each monitoring source in each monitoring point. At the same time, water level and flow rate monitoring are performed synchronously to form a water level time series and a flow rate time series.

[0009] The environmental impact monitoring source identification module is used to perform mutation analysis on the displacement time series of each monitoring source in each monitoring point, determine the mutation time, and extract the water level and flow velocity data at the corresponding time for fluctuation analysis, and then correlate the displacement mutation with the water level and flow velocity fluctuations to identify the environmental impact monitoring source.

[0010] The effective displacement monitoring module is used to use the monitoring results of water level and flow velocity in combination with environmental impact monitoring sources to select effective monitoring sources for effective displacement monitoring of each monitoring point in the subsequent displacement monitoring of the lowered steel cofferdam section.

[0011] The displacement offset identification module is used to extract the initial displacement of each monitoring point from the displacement time series of each monitoring source in each monitoring point during the test monitoring period, and then compare the effective displacement of each monitoring point with the initial displacement, identify the monitoring point with offset as the offset monitoring point, and determine the offset direction of the offset monitoring point.

[0012] The offset guidance analysis module is used to locate the layout position of the deviation monitoring point, and thus perform offset guidance analysis of the lowered steel cofferdam section in combination with the offset direction of the deviation monitoring point.

[0013] The offset adjustment module is used to make offset adjustments based on the offset guide of the lowered steel cofferdam section.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention performs multi-source displacement monitoring on the lowered cofferdam section during the trial monitoring period, and simultaneously performs water level and flow rate monitoring, and uses the mutation analysis of displacement to identify the environmental impact monitoring source, so that in the subsequent displacement monitoring, the monitoring results of water level and flow rate are combined to select effective monitoring sources for accurate displacement monitoring. This process realizes the effect verification before the implementation of displacement monitoring, and maximizes the accuracy and reliability of displacement data.

[0015] (2) When using the displacement monitoring results for analysis, the present invention identifies the displacement monitoring points and conducts displacement guidance analysis of the lowered steel cofferdam section in combination with the layout positions and displacement directions of these monitoring points. This process realizes the in-depth utilization of the displacement monitoring data and can provide targeted guidance for displacement correction, which is beneficial to improving the correction efficiency and effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0017] Figure 1 It is a schematic diagram of the connection of each module of the system of the present invention.

[0018] Figure 2 This is the front view of the double-walled steel cofferdam structure without bottom cover in the present invention.

[0019] Figure 3 It is a top view of the double-walled steel cofferdam structure without bottom cover in the present invention.

[0020] Figure numerals: 101 - branch bridge, 102 - steel cofferdam, 103 - internal support, 104 - riverbed bottom. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Reference Figure 1 As shown, a deep-water bottomless double-wall steel cofferdam construction displacement monitoring system includes a monitoring point layout module, a displacement trial monitoring module connected to the monitoring point layout module, an environmental impact monitoring source identification module connected to the displacement trial monitoring module, a displacement effective monitoring module connected to the environmental impact monitoring source identification module, a displacement offset identification module connected to the displacement effective monitoring module, an offset guidance analysis module connected to both the monitoring point layout module and the displacement offset identification module, and an offset adjustment module connected to the offset guidance analysis module.

[0023] The monitoring point layout module is used to layout monitoring points corresponding to corner points and internal support connection points of the lowered steel cofferdam section during the process of lowering the steel cofferdam in deep water.

[0024] It should be noted that the steel cofferdam is lowered to the bottom of the riverbed in deep water. This is because the riverbed, as a natural foundation support, can provide sufficient stability to prevent the cofferdam from displacement or overturning under the impact of water flow and external loads. At the same time, the riverbed, as a stable construction platform, can facilitate the entry and exit of construction personnel and mechanical equipment, thereby improving construction efficiency. Furthermore, the close contact between the cofferdam and the riverbed can effectively prevent pollutants such as mud and waste generated during the construction process from entering the water body, thereby protecting the water environment.

[0025] It should be further explained that internal supports are used to fix the steel cofferdam to ensure its stability and structural integrity. The internal support refers to the support structure set inside the steel cofferdam, which is usually composed of steel components. The internal support structure forms a stable frame by connecting with the cofferdam wall. The internal support can disperse and transfer external loads, reduce local stress on the cofferdam wall, and improve the overall structural integrity of the cofferdam. For specific steel cofferdam structures, see Figure 2 and Figure 3 shown.

[0026] Applied to the above description, when arranging monitoring points for the steel cofferdam, the four corner points at the bottom of the cofferdam and the internal support connection points are selected as monitoring points because the four corner points at the bottom of the cofferdam are usually the most sensitive points where the cofferdam contacts the riverbed. They are the support points of the entire structure and are easily affected by external loads and environmental factors, and have high displacement sensitivity. The internal support connection points are the key parts where the internal support structure of the cofferdam connects to the cofferdam wall. These positions are easily deformed and offset by stress concentration. It can be seen that these positions have a key impact on the overall stability and structural integrity of the cofferdam. By performing displacement monitoring at the four corner points at the bottom of the cofferdam and the internal support connection points, displacement monitoring of key positions can be achieved, reducing the waste of resources and cost increase caused by all-round deployment.

[0027] The displacement test monitoring module is used to use multiple monitoring sources to perform displacement, water level and flow rate monitoring at each monitoring point within the selected test monitoring period to form a displacement time series, water level time series and flow rate time series of each monitoring source in each monitoring point.

[0028] It should be added that the selection of the trial monitoring period mentioned above should not be too long or too short. First of all, it should not be too long because the lowering time of different steel cofferdam sections during the steel cofferdam lowering construction process cannot be too long apart, and the lowering of subsequent steel cofferdam sections needs to be adjusted according to the displacement data of the lowered steel cofferdam sections. This means that there is a time limit for the displacement monitoring of the lowered steel cofferdam sections. If the trial monitoring period is too long, the truly effective monitoring time cannot be guaranteed, resulting in delays in the construction progress and loss of timeliness of the monitoring data. Secondly, it should not be too short because a too short trial monitoring period may lead to insufficient data volume and inability to capture mutations in the monitoring source, thereby affecting the reliability and accuracy of the analysis and making it difficult to draw effective conclusions. Therefore, when selecting the trial monitoring period, you can refer to the historical steel cofferdam lowering construction records to obtain the average lowering interval of adjacent steel cofferdam sections, and use this as a benchmark duration to guide the selection of the trial monitoring period. Exemplarily, one-third of the benchmark duration can be taken as the trial monitoring duration. This principle ensures that there is enough data for analysis while avoiding an excessively long monitoring period that results in an inability to guarantee truly effective monitoring time. The completion time of the lowering of the steel cofferdam section is combined with the trial monitoring duration to form a trial monitoring period.

[0029] It should be further added that the multiple monitoring sources mentioned above can be underwater sonar, inclinometer, underwater GPS, etc., of course, not limited to these. Underwater sonar utilizes the good propagation characteristics of sound waves in water, can penetrate the water body, and obtain the precise position of underwater structures; the inclinometer uses the built-in gyroscope or accelerometer to measure the inclination angle of the structure to obtain the structure position; the underwater GPS obtains the position of underwater equipment or structures through an underwater GPS receiver.

[0030] It can be known that by adopting multiple monitoring sources to monitor the displacement of cofferdams, the displacement data of different monitoring sources can be obtained. On the one hand, the effectiveness of the monitoring sources can be verified, and the monitoring sources that perform stably in deep water environments can be screened out to ensure the reliability and accuracy of the data; on the other hand, when the deep water environment is stable, multi-source data can be integrated and data fusion technology can be used to improve the accuracy of displacement monitoring.

[0031] The environmental impact monitoring source identification module is used to perform mutation analysis on the displacement time series of each monitoring source in each monitoring point, determine the mutation time, and extract the water level and flow rate data of the corresponding time for fluctuation analysis, and then associate the displacement mutation with the water level and flow rate fluctuations to identify the environmental impact monitoring source.

[0032] In the manner in which the above scheme can be implemented, mutation analysis is performed on the displacement time series of each monitoring source in each monitoring point, referring to the following process: the displacement time series of each monitoring source in each monitoring point is formed into an observation set according to the displacement data generated in each mutation analysis, and adjacent displacement data in the observation set are formed into several displacement groups.

[0033] In the above example, assume that the observation set consisting of displacement data is , the displacement group formed in this example is , , , , .

[0034] It is important to know that in the time series of normal displacement data, displacement usually does not change suddenly. The reason is that the structure has a certain physical inertia, that is, the structure will not immediately change significantly when subjected to external forces. The change in displacement is a gradual process that requires a certain amount of time to accumulate. When the displacement data suddenly changes, it indicates that the displacement data is abnormal. It is very likely that the fluctuation of the underwater environment has caused the displacement monitoring to be disturbed. Therefore, by analyzing the sudden change of displacement data in the displacement time series, it can provide important clues for the identification of environmental impact monitoring sources.

[0035] The displacement data in each displacement group are calculated separately, and the mean is subtracted from the median displacement in the observation set and divided by the median displacement in the observation set to obtain the observation deviation corresponding to each displacement group, which is then compared with the set allowable deviation. Exemplarily, the allowable deviation is 0.1. If the observation deviation corresponding to a displacement group in the displacement time series of a monitoring source is greater than the allowable deviation, it is analyzed that there is a displacement monitoring mutation in the monitoring source, and the monitoring source is recorded as a mutation monitoring source, and the displacement group is recorded as a mutation displacement group.

[0036] Specifically, when performing mutation analysis, it is taken into account that mutation analysis is based on the displacement data that has been generated. Therefore, during mutation analysis, an observation set is constructed for the displacement data that has been generated, and then the displacement data in the observation set are grouped adjacently. This can ensure the continuity of the data and avoid analysis errors caused by data discontinuities. At the same time, adjacent grouping can better reflect local changes in displacement data and make it easier to identify mutation points, because mutation points are usually manifested as significant differences between adjacent data points. Furthermore, the data after adjacent grouping is easier to calculate and analyze efficiently, thereby improving the efficiency of mutation analysis.

[0037] In another specific aspect, the above-mentioned comparison of the average displacement data of each displacement group with the median displacement data in the observation set when calculating the observation deviation is because the median is the middle value of all the data in the observation set after being sorted by size, is insensitive to extreme values, and can better represent the center position of the observation set. Comparing the mean and median of each displacement group can reduce the influence of extreme values ​​on the results and ensure the robustness of the calculation results. The calculated observation deviation reflects the relative deviation degree of the mean of each displacement group relative to the median displacement of the entire observation set. By calculating the observation deviation, the deviation degree of the displacement data of each displacement group from the overall median displacement can be quantified. The allowable deviation is a pre-set threshold used to determine whether the displacement data is within the normal range. By comparing the observation deviation with the allowable deviation, the deviations of different displacement groups can be compared on the same scale to ensure the comparability and consistency of the analysis results. When the observation deviation of a displacement group exceeds the allowable deviation, it indicates that the displacement data of the displacement group has a significant deviation. At this time, it can be determined that the displacement group is a mutation displacement group. When there is a mutation displacement group in the displacement time series of a monitoring source, the monitoring source can be used as a mutation monitoring source.

[0038] The present invention can better capture the local changes of displacement data by grouping displacement time series data and calculating the observation deviation to identify the mutation monitoring source, and has a high practical value.

[0039] In another possible implementation of the above scheme, the mutation time is determined as follows: the monitoring time corresponding to the subsequent displacement in the mutation displacement group is extracted from the displacement time sequence of the mutation displacement group as the mutation time.

[0040] As an example of the above approach, assume that the mutation displacement group is , then the last displacement in the mutation displacement group is The monitoring time is taken as the mutation time.

[0041] In another possible implementation of the above scheme, the water level and flow rate data at the corresponding time are extracted for fluctuation analysis. See the following process: a coordinate system is constructed with time as the horizontal axis and water level and flow rate as the vertical axis, thereby generating water level change curves and flow rate change curves in the constructed coordinate system for the water level time series and flow rate time series corresponding to the sudden change monitoring source.

[0042] The points of the water level and flow rate data corresponding to the mutation time on the generated water level change curve and flow rate change curve are marked respectively, and the slope of the point is obtained and compared with the fluctuation slope set by the system. For example, the fluctuation slope can be 0.3. If the slope of the mutation time in the water level change curve at the point on the change curve reaches the fluctuation slope, it is recognized that the water level fluctuates at the mutation time. Similarly, if the slope of the mutation time in the flow rate change curve at the point on the change curve reaches the fluctuation slope, it is recognized that the flow velocity fluctuates at the mutation time.

[0043] It should be noted that the slope mentioned above is the slope after taking the absolute value.

[0044] When performing fluctuation analysis on water level and flow rate data based on mutation time, the present invention can intuitively display the changing trend of data by constructing water level change curves and flow rate change curves, making the analysis process more transparent and easy to understand. The slope of the curve corresponding to the mutation time can be calculated to quantify the rate of change of water level and flow rate near the mutation time point, providing a clear numerical indicator. Finally, the calculated slope is compared with the preset fluctuation slope to clearly determine whether the change is significant, avoiding errors caused by subjective judgment.

[0045] In a further implementation of the above scheme, the displacement mutation is associated with the water level and flow velocity fluctuations as follows: the total number of mutation times existing in the displacement time series of the mutation monitoring source is counted, and the frequency of water level fluctuations and flow velocity fluctuations at the mutation time is summarized, thereby using the association analysis formula

[0046] Obtain the correlation between displacement mutation and water level and flow velocity fluctuation , where , , They represent the total number of mutation times, the frequency of water level fluctuations and flow velocity fluctuations in the mutation monitoring source in the displacement time series, respectively. Represents a natural constant.

[0047] As an explanation of the above scheme, the relationship between them can be evaluated by examining the synchronization of displacement mutations with water level and flow velocity fluctuations when conducting correlation analysis. Specifically, if displacement mutations are usually accompanied by water level and flow velocity fluctuations, this can be regarded as strong evidence of the existence of a correlation between the two.

[0048] In a further implementation of the above scheme, the environmental impact monitoring source refers to the following identification process: the correlation between the displacement mutation corresponding to the mutation monitoring source and the water level and flow velocity fluctuations is compared with the effective correlation set by the system. If the correlation between the water level and flow velocity fluctuations and the displacement mutation corresponding to a mutation monitoring source reaches the effective correlation, the mutation monitoring source is used as the environmental impact monitoring source.

[0049] It is important to know that when performing correlation analysis, the correlation value range is usually between 0 and 1, where 0 means no correlation at all and 1 means complete correlation. In order to ensure the reliability of the analysis results, an effective correlation threshold can be set. For example, the effective correlation can be set to 0.8. This means that when the correlation data obtained from the analysis reaches or exceeds 0.8, it can be considered that there is a significant correlation between the displacement mutation and the water level and flow velocity fluctuations, thereby judging that the mutation monitoring source is affected by the environment.

[0050] By comparing the frequencies of water level fluctuations and flow velocity fluctuations at the sudden changes in the displacement time series of the environmental impact monitoring source, the corresponding tendency environmental indicators of the environmental impact monitoring source can be obtained.

[0051] Specifically, when the frequency of water level fluctuations at mutation time is greater than the frequency of flow velocity fluctuations, the environmental indicator of the environmental impact monitoring source is water level fluctuations, that is, the environmental impact monitoring source is mainly affected by water level fluctuations. When the frequency of water level fluctuations at mutation time is less than the frequency of flow velocity fluctuations, the environmental indicator of the environmental impact monitoring source is flow velocity fluctuations, that is, the environmental impact monitoring source is mainly affected by flow velocity fluctuations. When the frequency of water level fluctuations at mutation time is consistent with the frequency of flow velocity fluctuations, the environmental indicator of the environmental impact monitoring source is water level fluctuations and flow velocity fluctuations, that is, the environmental impact monitoring source is affected by both water level and flow velocity fluctuations.

[0052] The effective displacement monitoring module is used to select effective monitoring sources for effective displacement monitoring of each monitoring point by using the monitoring results of water level and flow rate in combination with environmental impact monitoring sources in subsequent displacement monitoring of the lowered steel cofferdam section.

[0053] In the preferred implementation of the above scheme, the effective monitoring source is selected according to the following process: the monitoring results of water level and flow velocity are used to identify fluctuations in real time. If no fluctuation is identified at a certain monitoring moment, all monitoring sources are regarded as effective monitoring sources at that monitoring moment. If fluctuation is identified at a certain monitoring moment, the fluctuation environment indicator is recorded, and then the tendency environment indicator corresponding to the environmental impact monitoring source is matched with the fluctuation environment indicator. If the tendency environment indicator corresponding to a certain environmental impact monitoring source is successfully matched with the fluctuation environment indicator, then the monitoring sources other than the environmental impact monitoring source are regarded as effective monitoring sources at that monitoring moment.

[0054] The above-mentioned fluctuation identification can be achieved by comparing the water level and flow velocity at each monitoring moment with the water level and flow velocity at the previous monitoring moment, calculating the water level contrast difference and flow velocity contrast difference, and then dividing the absolute value of the water level contrast difference by the duration of adjacent monitoring moments to obtain the water level change rate; similarly, dividing the absolute value of the flow velocity contrast difference by the duration of adjacent monitoring moments to obtain the flow velocity change rate; then comparing the water level change rate and the flow velocity change rate with the fluctuation slope. Since the fluctuation slope reflects the fluctuation change rate, the water level change rate and the flow velocity change rate can be compared with the fluctuation slope. If the water level change rate and the flow velocity change rate do not reach the fluctuation slope, it is identified as no fluctuation; otherwise, it is identified as fluctuation. At the same time, if the water level change rate reaches the fluctuation slope, the water level is used as an indicator of the fluctuation environment; if the flow velocity change rate reaches the fluctuation slope, the flow velocity is used as an indicator of the fluctuation environment.

[0055] Further preferably, the effective displacement monitoring of each monitoring point is performed as follows: if there are multiple effective monitoring sources selected at a certain monitoring time, the displacement monitoring results of each effective monitoring source are scale-normalized and transformed to ensure that the data of different monitoring sources are on the same scale, eliminate the influence of dimension, and make the data comparable; the standard deviation of the normalized displacement monitoring results is calculated, and the standard deviation calculation result is compared with the set reasonable standard deviation. Exemplarily, the reasonable standard deviation may be 0.3; if the standard deviation calculation result is within the reasonable standard deviation, the normalized displacement monitoring results are averaged to obtain the effective displacement; if the standard deviation calculation result is higher than the reasonable standard deviation, the displacement monitoring results of each effective monitoring source after normalization are compared with the displacement monitoring results of other effective monitoring sources after normalization to calculate the standard deviation, and the displacement monitoring data of the effective monitoring source corresponding to the minimum standard deviation is selected as the effective displacement.

[0056] It should be noted that the standard deviation mentioned above is an indicator to measure the degree of data dispersion. The consistency of the data can be evaluated through standard deviation calculation. If the standard deviation is within the reasonable standard deviation, it means that the data consistency is good. If the standard deviation exceeds the reasonable standard deviation, the displacement monitoring results of each effective monitoring source after normalization are used as the average data in the standard deviation calculation, and the displacement monitoring data of other effective monitoring sources after normalization are calculated with the average data for standard deviation, and then the effective monitoring source corresponding to the minimum standard deviation is taken, which can reduce the impact of outliers and improve the reliability of the data.

[0057] If there is only one valid monitoring source selected at a certain monitoring time, the displacement monitoring data of this monitoring source is taken as the valid displacement.

[0058] The displacement offset identification module is used to extract the initial displacement of each monitoring point from the displacement time series of each monitoring source in each monitoring point during the test monitoring period, and then compare the effective displacement of each monitoring point with the initial displacement, identify the monitoring point with offset as the offset monitoring point, and determine the offset direction of the offset monitoring point.

[0059] In the optional implementation of the above scheme, since the initial displacement refers to the displacement when the cofferdam section is first lowered to the bottom of the riverbed, the displacement mutation analysis has not been performed at this time. Therefore, the initial displacement data extracted from the displacement time series of each monitoring source in each monitoring point can be scaled and normalized, and then the average value is taken to obtain the initial displacement.

[0060] In a further optional implementation of the above scheme, the monitoring of the displacement of the monitoring points by the present invention covers displacements in different directions, specifically including vertical and non-vertical directions, wherein the vertical direction generally refers to the displacement along the direction of gravity, reflecting the settlement of the cofferdam, and the non-vertical direction may include horizontal, vertical, oblique displacement, etc., reflecting the structural deformation of the cofferdam.

[0061] In the process of identifying the offset monitoring points and offset directions, the effective displacement of each monitoring point can be compared with the initial displacement to obtain the displacement difference of each monitoring point in each direction.

[0062] The displacement difference of each monitoring point in each direction is compared with the set warning displacement difference. For example, the warning displacement difference can be set to 5 mm. If the displacement difference of a monitoring point in a certain direction reaches the warning displacement difference, the monitoring point is identified as offset and this direction is used as the offset direction.

[0063] The offset guidance analysis module is used to locate the position of the deviation monitoring point, and thus perform an offset guidance analysis of the lowered steel cofferdam section in combination with the offset direction of the deviation monitoring point. The specific analysis is as follows: by comparing and analyzing the offset directions of the offset monitoring points, the monitoring points with the same offset direction are classified to form a set of offset monitoring points corresponding to the vertical offset direction and a set of offset monitoring points corresponding to the non-vertical offset direction.

[0064] The offset monitoring points corresponding to the vertical offset direction are concentrated and the layout positions of the offset monitoring points are compared, and the proportion of the offset monitoring points with corner points as the layout positions is summarized, which is recorded as the corner point offset distribution proportion.

[0065] The offset monitoring points corresponding to the non-vertical offset direction are concentrated and the layout positions of the offset monitoring points are compared, and the proportion of the offset monitoring points whose layout positions are internal support connection points is summarized and recorded as the support offset distribution proportion.

[0066] The proportion of vertical offset monitoring points and the proportion of non-vertical offset monitoring points are counted from the offset monitoring point set corresponding to the vertical offset direction and the offset monitoring point set corresponding to the non-vertical offset direction respectively.

[0067] The geological subsidence guidance tendency index is obtained by multiplying the proportion of vertical offset monitoring points with the proportion of corner point offset distribution.

[0068] It should be understood that the proportion of vertical offset monitoring points reflects the overall settlement of the cofferdam in the vertical direction, while the corner points are usually the key parts of the structure, and their settlement has an important impact on the stability of the overall structure. By multiplying the proportion of vertical offset monitoring points with the proportion of corner point offset distribution, the multiplication result can comprehensively evaluate the joint impact of these two factors. Only when the vertical settlement and corner point settlement are both serious, the multiplication result will increase significantly, indicating that the settlement problem of the cofferdam in the vertical direction is more serious, and the settlement of the corner point position is also more obvious, thereby more accurately reflecting the potential risks of the structure.

[0069] It should be understood that the proportion of non-vertical offset monitoring points reflects the overall deformation of the cofferdam in the non-vertical direction, while the internal support connection points are the key connection parts of the structure, and their deformation has an important impact on the stability of the overall structure. By multiplying the proportion of non-vertical offset monitoring points with the proportion of support offset distribution, the impact of structural deformation on the internal support connection points can be comprehensively evaluated.

[0070] The geological settlement guidance tendency index and the deformation guidance tendency index are numerically compared to determine the offset guidance of the lowered steel cofferdam section. Specifically, the geological settlement guidance tendency index can be compared with the deformation guidance tendency index. If the geological settlement guidance tendency index is greater than the deformation guidance tendency index, it is considered that the offset guidance of the lowered steel cofferdam section is mainly geological settlement; conversely, if the deformation guidance tendency index is greater than the geological settlement guidance tendency index, it is considered that the offset guidance is mainly structural deformation. When the two are consistent, it can be considered that the offset guidance is both geological settlement and structural deformation.

[0071] The offset adjustment module is used to perform offset adjustment according to the offset guide of the lowered steel cofferdam section.

[0072] As a specific implementation method of the above scheme, when the offset guide of the lowered steel cofferdam section is geological settlement, the stability and bearing capacity of the foundation can be ensured by strengthening the foundation and increasing support. When the offset guide of the lowered steel cofferdam section is structural deformation, support reinforcement can be carried out to ensure the rigidity and stability of the structure. In this way, the offset of the cofferdam can be effectively and targetedly adjusted, while improving the safety and reliability of the cofferdam lowering construction.

[0073] The above contents are merely examples and explanations of the concept of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, they shall all fall within the protection scope of the present invention.

Claims

1. A deepwater bottomless double-walled steel cofferdam construction displacement monitoring system, characterized in that: Includes the following modules: The monitoring point layout module is used to layout the monitoring points corresponding to the corner points and internal support connection points of the lowered steel cofferdam section during the process of lowering the steel cofferdam in deep water; The displacement test monitoring module is used to use multiple monitoring sources to perform displacement monitoring at each monitoring point during the selected test monitoring period to form a displacement time series of each monitoring source at each monitoring point, and at the same time, synchronously perform water level and flow rate monitoring to form a water level time series and a flow rate time series; The environmental impact monitoring source identification module is used to perform mutation analysis on the displacement time series of each monitoring source in each monitoring point, determine the mutation time, and extract the water level and flow velocity data at the corresponding time for fluctuation analysis, and then associate the displacement mutation with the water level and flow velocity fluctuations to identify the environmental impact monitoring source; The effective displacement monitoring module is used to select effective monitoring sources for effective displacement monitoring of each monitoring point by using the monitoring results of water level and flow velocity combined with environmental impact monitoring sources in the subsequent displacement monitoring of the lowered steel cofferdam section; The displacement offset identification module is used to extract the initial displacement of each monitoring point from the displacement time series of each monitoring source in each monitoring point during the test monitoring period, and then compare the effective displacement of each monitoring point with the initial displacement, identify the monitoring point with offset as the offset monitoring point, and determine the offset direction of the offset monitoring point; The offset guidance analysis module is used to locate the layout position of the deviation monitoring point, and thus conduct offset guidance analysis of the lowered steel cofferdam section in combination with the offset direction of the deviation monitoring point; The offset adjustment module is used to make offset adjustments based on the offset guide of the lowered steel cofferdam section.

2. A deepwater bottomless double-walled steel cofferdam construction displacement monitoring system as claimed in claim 1, characterized in that: The mutation analysis of the displacement time series of each monitoring source in each monitoring point refers to the following process: The displacement time series of each monitoring source in each monitoring point is used to form an observation set according to the displacement data generated in each mutation analysis, and the adjacent displacement data in the observation set are used to form several displacement groups; The displacement data in each displacement group are calculated separately, and the difference between the mean and the median displacement in the observation set is divided by the median displacement in the observation set to obtain the observation deviation corresponding to each displacement group, which is then compared with the set allowable deviation. If the observation deviation corresponding to a displacement group in the displacement time series of a monitoring source is greater than the allowable deviation, it is analyzed that there is a displacement monitoring mutation in the monitoring source, and the monitoring source is recorded as a mutation monitoring source, and the displacement group is recorded as a mutation displacement group.

3. A deepwater bottomless double-walled steel cofferdam construction displacement monitoring system as claimed in claim 2, characterized in that: The process of determining the mutation time is as follows: The monitoring time corresponding to the subsequent displacement in the mutation displacement group is extracted from the displacement time series of the mutation displacement group as the mutation time.

4. A deepwater bottomless double-walled steel cofferdam construction displacement monitoring system as claimed in claim 1, characterized in that: The extraction of water level and flow rate data at the corresponding time for fluctuation analysis refers to the following process: A coordinate system is constructed with time as the horizontal axis and water level and flow velocity as the vertical axis, thereby generating a water level change curve and a flow velocity change curve in the constructed coordinate system for the water level time series and flow velocity time series corresponding to the mutation monitoring source; The points of water level and flow rate data corresponding to the mutation time on the generated water level change curve and flow rate change curve are marked respectively, and the slope of the point is obtained and compared with the fluctuation slope set by the system. If the slope of the mutation time on the change curve of the water level change curve reaches the fluctuation slope, it is recognized that the water level fluctuates at the mutation time. Similarly, if the slope of the mutation time on the change curve of the flow rate change curve reaches the fluctuation slope, it is recognized that the flow velocity fluctuates at the mutation time.

5. A deepwater bottomless double-walled steel cofferdam construction displacement monitoring system as claimed in claim 4, characterized in that: The operation of correlating the displacement mutation with the water level and flow velocity fluctuation is as follows: The total number of mutation times in the displacement time series of the mutation monitoring source is counted, and the frequency of water level fluctuation and flow velocity fluctuation at the mutation time is summarized. Obtain the correlation between displacement mutation and water level and flow velocity fluctuation , where , , They represent the total number of mutation times, the frequency of water level fluctuations and flow velocity fluctuations in the mutation monitoring source in the displacement time series, respectively. Represents a natural constant.

6. A deepwater bottomless double-walled steel cofferdam construction displacement monitoring system as claimed in claim 5, characterized in that: The environmental impact monitoring sources refer to the following identification process: Compare the correlation between the sudden displacement change and the water level and flow velocity fluctuations of the sudden change monitoring source with the effective correlation of the system setting. If the correlation between the water level and flow velocity fluctuations and the sudden displacement change of a sudden change monitoring source reaches the effective correlation, then the sudden change monitoring source will be used as the environmental impact monitoring source. By comparing the frequencies of water level fluctuations and flow velocity fluctuations at the sudden changes in the displacement time series of the environmental impact monitoring source, the corresponding tendency environmental indicators of the environmental impact monitoring source can be obtained.

7. A deepwater bottomless double-walled steel cofferdam construction displacement monitoring system as claimed in claim 6, characterized in that: The process of selecting effective monitoring sources by using the monitoring results of water level and flow velocity in combination with environmental impact monitoring sources is as follows: The monitoring results of water level and flow velocity are used to identify fluctuations in real time. If no fluctuation is identified at a certain monitoring moment, all monitoring sources at that monitoring moment are regarded as effective monitoring sources. If fluctuation is identified at a certain monitoring moment, the fluctuation environmental indicators are recorded, and then the tendency environmental indicators corresponding to the environmental impact monitoring sources are matched with the fluctuation environmental indicators. If the tendency environmental indicators corresponding to an environmental impact monitoring source are successfully matched with the fluctuation environmental indicators, then at that monitoring moment, the monitoring sources except the environmental impact monitoring source are regarded as effective monitoring sources.

8. A deepwater bottomless double-walled steel cofferdam construction displacement monitoring system as claimed in claim 1, characterized in that: The effective displacement monitoring of each monitoring point is performed as follows: If there are multiple effective monitoring sources selected at a certain monitoring time, the displacement monitoring results of each effective monitoring source will be scale-normalized, and the standard deviation of the normalized displacement monitoring results will be calculated. At the same time, the standard deviation calculation result will be compared with the set reasonable standard deviation. If the standard deviation calculation result is within the reasonable standard deviation, the normalized displacement monitoring results will be averaged to obtain the effective displacement. If the standard deviation calculation result is higher than the reasonable standard deviation, the displacement monitoring results of each effective monitoring source after normalization will be compared with the displacement monitoring results of other effective monitoring sources after normalization to calculate the standard deviation, and the displacement monitoring data of the effective monitoring source corresponding to the minimum standard deviation will be selected as the effective displacement. If there is only one valid monitoring source selected at a certain monitoring time, the displacement monitoring data of this monitoring source is taken as the valid displacement.

9. A deepwater bottomless double-walled steel cofferdam construction displacement monitoring system as claimed in claim 1, characterized in that: The monitoring point identified as having a deviation is recorded as a deviation monitoring point, and the deviation direction of the deviation monitoring point is determined as shown in the following process: Compare the effective displacement of each monitoring point with the initial displacement to obtain the displacement difference of each monitoring point in each direction; The displacement difference of each monitoring point in each direction is compared with the set warning displacement difference. If the displacement difference of a monitoring point in a certain direction reaches the warning displacement difference, the monitoring point is identified as offset and the direction is used as the offset direction.

10. A deepwater bottomless double-walled steel cofferdam construction displacement monitoring system as claimed in claim 1, characterized in that: The offset guidance analysis of the lowered steel cofferdam section is as follows: By comparing and analyzing the offset directions of the offset monitoring points, the monitoring points with the same offset direction are classified into a set of offset monitoring points corresponding to the vertical offset direction and a set of offset monitoring points corresponding to the non-vertical offset direction; The offset monitoring points corresponding to the vertical offset direction are concentrated and the positions of the offset monitoring points are compared, and the proportion of the offset monitoring points whose positions are corner points is recorded as the corner point offset distribution proportion; The offset monitoring points corresponding to the non-vertical offset direction are concentrated and the layout positions of the offset monitoring points are compared, and the proportion of the offset monitoring points whose layout positions are the internal support connection points is recorded as the support offset distribution proportion; Count the proportion of vertical offset monitoring points and the proportion of non-vertical offset monitoring points from the offset monitoring point set corresponding to the vertical offset direction and the offset monitoring point set corresponding to the non-vertical offset direction respectively; The geological settlement orientation index is obtained by multiplying the proportion of vertical offset monitoring points with the proportion of corner point offset distribution; The deformation guidance tendency index is obtained by multiplying the proportion of non-vertical offset monitoring points and the proportion of support offset distribution; The geological settlement guidance tendency index is numerically compared with the deformation guidance tendency index to determine the offset guidance of the lowered steel cofferdam section.

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