A method and system for monitoring dynamic load during pile underpinning process

Abstract

The application provides a method and system for monitoring dynamic load in pile underpinning process, and relates to the technical field of load monitoring. The method comprises the following steps: establishing a four-span continuous beam mechanical model and arranging a distributed jack array; compensating the deflection deformation of the steel box girder by controlling the jacking displacement of the jacks, so that the main girder keeps the original elevation, and the jacking force and the jacking displacement of the jack array are obtained; obtaining the pressure data of each jack; determining the active bearing efficiency factor of the cross beam according to the jacking force and the jacking displacement; obtaining the first distance between each jack; determining the stress of the cross beam; monitoring the vehicle load data and speed data of multiple vehicles on the bridge; determining the dynamic load transfer rate according to the vehicle load data and the speed data; and determining the dynamic load transfer condition. According to the application, the dynamic load transfer condition can be monitored according to the active bearing efficiency factor, the stress and the dynamic load transfer rate of the cross beam, and the comprehensiveness of the monitoring is improved.

Description

Technical Field

[0001] This invention relates to the field of load monitoring technology, and in particular to a method and system for monitoring dynamic loads during the pile underpinning process. Background Technology

[0002] Current technologies monitor pressure and stress characteristics using dynamic load monitoring devices and support load monitoring systems, but do not consider the active bearing efficiency factor and stress of the diaphragm beam, or the impact of vehicle conditions on the dynamic load transfer during pile replacement. In other words, they cannot monitor the dynamic load transfer based on the active bearing efficiency factor, stress, and dynamic load transfer rate of the diaphragm beam.

[0003] The information disclosed in the background section of this application is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] This invention provides a method and system for monitoring dynamic loads during the pile underpinning process, which can solve the technical problem that related technologies cannot monitor the dynamic load transfer status based on the active bearing efficiency factor, stress, and dynamic load transfer rate of the crossbeam.

[0005] According to a first aspect of the present invention, a method for monitoring dynamic loads during the pile underpinning process is provided, comprising: establishing a mechanical model of a four-span continuous beam; arranging a distributed array of jacks between the main beam and the steel box girder of the bridge to be underpinned, wherein each jack in the jack array is equipped with a displacement sensor and a pressure sensor; compensating for the deflection deformation of the steel box girder by controlling the lifting displacement of the jacks to maintain the original elevation of the main beam; acquiring the lifting force and lifting displacement of the jack array during the current lifting monitoring cycle; acquiring the pressure data of each jack; and based on the lifting force and lifting displacement... The displacement is used to determine the active load-bearing efficiency factor of the diaphragm in the current jacking monitoring cycle; the first distance between each jack is obtained; the stress of the diaphragm in the current jacking monitoring cycle is determined based on the pressure data and the first distance; during the current jacking monitoring cycle, the vehicle load data and speed data of multiple vehicles on the bridge are monitored; the dynamic load transfer rate in the current jacking monitoring cycle is determined based on the vehicle load data and the speed data; and the dynamic load transfer status is determined based on the active load-bearing efficiency factor of the diaphragm, the stress of the diaphragm, and the dynamic load transfer rate.

[0006] Further, based on the lifting force and the lifting displacement, the active bearing efficiency factor of the transverse diaphragm in the current lifting monitoring cycle is determined, including: obtaining the dead load of the bridge superstructure and the maximum allowable deflection of the steel box girder; and determining the active bearing efficiency factor of the transverse diaphragm in the current lifting monitoring cycle based on the dead load of the bridge superstructure, the maximum allowable deflection of the steel box girder, the lifting force, and the lifting displacement.

[0007] Furthermore, based on the dead load of the bridge superstructure, the maximum allowable deflection of the steel box girder, the jacking force, and the jacking displacement, the active bearing efficiency factor of the transverse diaphragm in the current jacking monitoring cycle is determined, including: according to the formula: Determine the active load-bearing efficiency factor of the transverse diaphragm during the current jacking monitoring cycle. ,in, The lifting force of the jack array, Let be the lifting displacement of the i-th jack. This refers to the dead load on the bridge superstructure. Let be the maximum allowable deflection of the steel box girder, n be the number of jacks, i ≤ n, and i and n are both positive integers.

[0008] Further, determining the stress of the crossbeam in the current jacking monitoring cycle based on the pressure data and the first distance includes: obtaining the effective height and effective width of the crossbeam according to the bridge structure design drawings; and determining the stress of the crossbeam in the current jacking monitoring cycle based on the effective height, the effective width, the pressure data, and the first distance.

[0009] Further, based on the effective height, the effective width, the pressure data, and the first distance, the stress of the transverse diaphragm in the current lifting monitoring cycle is determined, including: according to the formula: Determine the stress of the transverse diaphragm during the current jacking monitoring cycle. Where K is the load distribution correction factor. Let L be the pressure data of the i-th jack, L be the first distance, B be the effective width of the crossbeam, H be the effective height of the crossbeam, n be the number of jacks, i ≤ n, and i and n are both positive integers.

[0010] Further, based on the vehicle load data and the speed data, the dynamic load transfer rate for the current lifting monitoring cycle is determined, including: obtaining the average vehicle load at multiple moments in the current lifting monitoring cycle based on the vehicle load data; fitting the average vehicle load at multiple moments in the current lifting monitoring cycle to obtain an average vehicle load time function; obtaining the average speed at multiple moments in the current lifting monitoring cycle based on the speed data; fitting the average speed at multiple moments in the current lifting monitoring cycle to obtain an average speed time function; obtaining the existing pier reaction force and elevation maintenance deviation at multiple moments in the current lifting monitoring cycle; fitting the existing pier reaction force at multiple moments in the current lifting monitoring cycle to obtain an existing pier reaction force time function; fitting the elevation maintenance deviation at multiple moments in the current lifting monitoring cycle to obtain an elevation maintenance deviation time function; obtaining the stiffness of the structure after replacement and the stiffness of the original structure; and determining the dynamic load transfer rate for the current lifting monitoring cycle based on the average vehicle load time function, the average speed time function, the existing pier reaction force time function, the elevation maintenance deviation time function, the stiffness of the structure after replacement, and the stiffness of the original structure.

[0011] Further, based on the average vehicle load time function, the average speed time function, the existing pier reaction force time function, the elevation maintenance deviation time function, the stiffness of the replaced structure, and the stiffness of the original structure, the dynamic load transfer rate of the current jacking monitoring cycle is determined, including: according to the formula: Determine the dynamic load transfer rate for the current jacking monitoring cycle. ,in, The time function of the existing pier column reaction force. The elevation maintenance deviation time function. Let be the average vehicle load time function. It is a function of average velocity over time. To improve the structural stiffness after replacement, The original structural stiffness is represented by T, and the jacking monitoring cycle duration is represented by T.

[0012] Further, based on the active load-bearing efficiency factor of the diaphragm, the stress of the diaphragm, and the dynamic load transfer rate, the dynamic load transfer status is determined, including: if the active load-bearing efficiency factor of the diaphragm is within a preset active load-bearing efficiency factor range, then the active load is deemed safe; if the ratio between the stress of the diaphragm in the current lifting monitoring cycle and the stress of the diaphragm in the previous lifting monitoring cycle is less than 5% and the stress of the diaphragm in the current lifting monitoring cycle is less than a preset stress of the diaphragm, then the next stage of lifting is initiated; if the dynamic load transfer rate is less than a preset dynamic load transfer rate, then the dynamic load transfer is deemed complete.

[0013] According to a second aspect of the present invention, a dynamic load monitoring system for the pile underpinning process is provided, comprising: a jack array module for establishing a mechanical model of a four-span continuous beam, wherein a distributed jack array is arranged between the main beam and the steel box girder of the bridge to be underpinned, wherein each jack in the jack array is equipped with a displacement sensor and a pressure sensor; a jacking force and jacking displacement module for compensating for the deflection deformation of the steel box girder by controlling the jacking displacement of the jacks, so that the main beam maintains its original elevation, and acquiring the jacking force and jacking displacement of the jack array in the current jacking monitoring cycle; a pressure data module for acquiring the pressure data of each jack; and an active bearing efficiency factor module for determining the load based on the jacking force and the jacking displacement. The system comprises the following modules: a first distance module for determining the active load-bearing efficiency factor of the transverse diaphragm during the current jacking monitoring cycle; a stress module for determining the stress of the transverse diaphragm during the current jacking monitoring cycle based on the pressure data and the first distance; a vehicle load data and speed data module for monitoring the vehicle load data and speed data of multiple vehicles on the bridge during the current jacking monitoring cycle; a dynamic load transfer rate module for determining the dynamic load transfer rate during the current jacking monitoring cycle based on the vehicle load data and the speed data; and a dynamic load transfer status module for determining the dynamic load transfer status based on the active load-bearing efficiency factor of the transverse diaphragm, the stress of the transverse diaphragm, and the dynamic load transfer rate.

[0014] Technical Effects: According to this invention, by controlling the lifting displacement of the jacks to compensate for the deflection deformation of the steel box girder, the main girder maintains its original elevation, effectively reducing the impact of bridge structural deformation caused by the replacement process on overall stability. The active load-bearing efficiency factor and stress of the crossbeams can accurately assess their load-bearing performance during the replacement process, helping to determine the safety of active load-bearing and the initiation of the next stage of lifting. By considering the impact of vehicle dynamic loads on the bridge structure and monitoring the dynamic load transfer rate, the stability and feasibility of the pile replacement process can be assessed, improving the comprehensiveness of monitoring. When determining the active load-bearing efficiency factor of the crossbeams, it can be determined through the dead load of the bridge superstructure, the maximum allowable deflection of the steel box girder, the lifting force, and the lifting displacement, thereby assessing the load-bearing performance of the crossbeams during the replacement process, promptly understanding whether the load-bearing state of the crossbeams is within a reasonable range, and improving the safety of the lifting. When determining the stress of the crossbeam, the effective height, effective width, pressure data, and initial distance can be used to determine the stress state of the crossbeam during the replacement process. This quantifies the stress state of the crossbeam during the replacement process, thereby determining the initiation of the next stage of jacking, reducing the risk of structural failure due to sudden stress changes, and improving the safety of the crossbeam under load. When determining the dynamic load transfer rate, it can be based on comparing the internally transferred fluctuation energy with the total external input energy, and considering stiffness changes. This allows for a comprehensive evaluation of the dynamic load transfer quality, taking into account the impact of vehicle dynamic loads on the bridge structure, thereby assessing the stability and feasibility of the pile replacement process and improving the comprehensiveness of monitoring.

[0015] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Other features and aspects of the invention will become clearer from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic flowchart of a dynamic load monitoring method for pile underpinning according to an embodiment of the present invention is shown as an example.

[0018] Figure 2 An exemplary flowchart is shown for calculating the active load-bearing efficiency factor of a transverse diaphragm according to an embodiment of the present invention;

[0019] Figure 3An exemplary flowchart for calculating the stress of a crossbeam according to an embodiment of the present invention is shown;

[0020] Figure 4 An exemplary flowchart for calculating the dynamic load transfer rate according to an embodiment of the present invention is shown;

[0021] Figure 5 A flowchart for determining the dynamic load transfer status according to an embodiment of the present invention is shown as an example;

[0022] Figure 6 A block diagram of a dynamic load monitoring system for the pile underpinning process according to an embodiment of the present invention is shown as an example. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0025] Figure 1 An exemplary flowchart of a dynamic load monitoring method for pile underpinning according to an embodiment of the present invention is shown. The method includes: Step S1, establishing a mechanical model of a four-span continuous beam, and arranging a distributed jack array between the main beam and the steel box girder of the bridge to be underpinned, wherein each jack in the jack array is equipped with a displacement sensor and a pressure sensor; Step S2, compensating for the deflection deformation of the steel box girder by controlling the lifting displacement of the jacks to maintain the original elevation of the main beam, and obtaining the lifting force and lifting displacement of the jack array in the current lifting monitoring cycle; Step S3, obtaining the pressure data of each jack; Step S4, based on the lifting force and the... Step S5: Determine the active load-bearing efficiency factor of the diaphragm during the current lifting monitoring cycle by measuring the lifting displacement; Step S6: Obtain the first distance between each jack; Step S7: Determine the stress of the diaphragm during the current lifting monitoring cycle based on the pressure data and the first distance; Step S8: Monitor the vehicle load data and speed data of multiple vehicles on the bridge during the current lifting monitoring cycle; Step S9: Determine the dynamic load transfer rate during the current lifting monitoring cycle based on the vehicle load data and the speed data; Step S10: Determine the dynamic load transfer status based on the active load-bearing efficiency factor of the diaphragm, the stress of the diaphragm, and the dynamic load transfer rate.

[0026] The dynamic load monitoring method for the pile replacement process according to an embodiment of the present invention compensates for the deflection deformation of the steel box girder by controlling the lifting displacement of the jacks, thus maintaining the original elevation of the main girder and effectively reducing the impact of bridge structural deformation caused by the replacement process on the overall stability. The active load-bearing efficiency factor and stress of the crossbeams can accurately assess the load-bearing performance of the crossbeams during the replacement process, helping to determine the safety of active load-bearing and the initiation of the next stage of lifting. By considering the impact of vehicle dynamic loads on the bridge structure and monitoring the dynamic load transfer rate, the stability and feasibility of the pile replacement process can be evaluated, improving the comprehensiveness of the monitoring.

[0027] According to one embodiment of the present invention, in step S1, relevant design data of the bridge to be replaced is collected, including the bridge's span, cross-sectional dimensions, material properties (e.g., concrete strength grade, elastic modulus, etc.), support conditions, etc. A mechanical model of the four-span continuous beam is established using professional structural mechanics analysis software (e.g., ANSYS, MIDAS, etc.) based on the structural form of a four-span continuous beam. Jacks are installed between the main beam and the steel box girder, with 10 jacks at each span end, requiring 20 jacks per span. The position between the support piles and the replacement beam is replaced by temporary structures such as steel sand buckets. During the upward force application of the jacks, the temporary structures will gradually (e.g., in 5 stages of jacking) bear the dead load of the bridge superstructure, reducing the stress on the existing piers. Each jack is equipped with a displacement sensor and a pressure sensor to measure the jack's lifting displacement and pressure data, respectively.

[0028] According to one embodiment of the present invention, in step S2, the flexural deformation of the steel box girder is compensated by controlling the lifting displacement of the jacks, so that the main beam maintains its original elevation. That is, the jacking force applied by each jack is basically the same (i.e., the lifting force of each jack is the same). At the same time, it is ensured that the downward flexural deformation of the supporting beam after each loading stage is completed is compensated by the lifting height of the jacks, so that the elevation of the bottom of each main beam remains unchanged. In the end, the dead load of the upper part of the bridge is borne entirely by the supporting beam. With precise control, the crossbeam will basically not deform. The jacking monitoring cycle is the time from the start to the end of the jacking plus the stabilization time. That is, each jacking monitoring cycle can be set to 10 minutes, 20 minutes, etc. This invention does not limit this. The required jacking displacement of each jack within each jacking monitoring cycle is determined. For example, deflection monitoring points are set at key parts of the steel box girder (mid-span, near supports, etc., where deflection deformation is prone to occur). High-precision measuring instruments such as dial gauges and electronic levels can be used to monitor the deflection changes of the steel box girder at the deflection monitoring points. Based on the monitored steel box girder deflection data, the jacking displacement of the jacks is adjusted through the control system.

[0029] According to one embodiment of the present invention, in step S3, pressure data of each jack is obtained based on the pressure sensor equipped with each jack.

[0030] According to one embodiment of the present invention, in step S4, the active bearing efficiency factor of the transverse diaphragm in the current lifting monitoring cycle is determined based on the lifting force and the lifting displacement.

[0031] Figure 2 A flowchart illustrating the calculation of the active load-bearing efficiency factor of a transverse diaphragm according to an embodiment of the present invention is shown.

[0032] According to an embodiment of the present invention, step S4 includes: step S41, obtaining the dead load of the bridge superstructure and the maximum allowable deflection of the steel box girder; step S42, determining the active bearing efficiency factor of the transverse diaphragm in the current lifting monitoring cycle based on the dead load of the bridge superstructure, the maximum allowable deflection of the steel box girder, the lifting force and the lifting displacement.

[0033] According to one embodiment of the present invention, the dead load of the bridge superstructure and the maximum allowable deflection of the steel box girder (e.g., one-five-hundredth of the main girder span) are obtained based on the bridge design drawings. The active load-bearing efficiency factor can comprehensively reflect the active load-bearing capacity of the transverse diaphragm during the current jacking monitoring cycle.

[0034] According to one embodiment of the present invention, the active bearing efficiency factor of the transverse diaphragm in the current jacking monitoring cycle is determined based on the dead load of the bridge superstructure, the maximum allowable deflection of the steel box girder, the jacking force, and the jacking displacement, including: determining the active bearing efficiency factor of the transverse diaphragm in the current jacking monitoring cycle according to formula (1). ,

[0035] (1),

[0036] in, The lifting force of the jack array, Let be the lifting displacement of the i-th jack. This refers to the dead load on the bridge superstructure. Let be the maximum allowable deflection of the steel box girder, n be the number of jacks, i ≤ n, and i and n are both positive integers.

[0037] According to an embodiment of the present invention, in formula (1), Let represent the lifting force of the jack array and the lifting displacement of the i-th jack, and let represent the effective mechanical work output by the i-th jack during the lifting process in the current lifting monitoring cycle. This refers to the total effective mechanical work output by all jacks during the lifting process. The greater this total effective mechanical work, the more significant the effect of the jack array on the bridge structure, and the stronger its ability to compensate for or adjust structural deformation. It is the product of the dead load of the bridge superstructure and the maximum allowable deflection of the steel box girder, representing the benchmark of potential energy change generated by the dead load of the bridge superstructure under the maximum allowable deflection of the steel box girder. This is the ratio of the total effective mechanical work to the potential energy change benchmark generated by the dead load of the bridge superstructure under the maximum allowable deflection of the steel box girder. It represents the relative value of the energy effect generated by the jacking relative to the energy effect allowed by the structure based on the dead load and design requirements. If the relative value is within a reasonable range, it indicates that the structure is working normally under active control and dead load. If the relative value is not within a reasonable range, for example, if the relative value is too small, it means that the active control effect is not obvious and the jacking displacement is too small; if the relative value is too large, it means that the jacking displacement is too large and it indicates that there is a safety hazard in the structure, and further inspection and reinforcement measures are required.

[0038] In this way, the active load-bearing efficiency factor of the crossbeam can be determined by the dead load of the bridge superstructure, the maximum allowable deflection of the steel box girder, the jacking force, and the jacking displacement. This allows for the assessment of the load-bearing performance of the crossbeam during the replacement process, timely understanding of whether the load-bearing state of the crossbeam is within a reasonable range, and improvement of the safety of the jacking.

[0039] According to one embodiment of the present invention, in step S5, a first distance between two jack marking points can be directly measured using a measuring tape or a laser rangefinder, and the distances between the two jacks are equal.

[0040] According to one embodiment of the present invention, in step S6, the stress of the crossbeam in the current lifting monitoring cycle is determined based on the pressure data and the first distance.

[0041] Figure 3 An exemplary flowchart for calculating the stress of a crossbeam according to an embodiment of the present invention is shown.

[0042] According to an embodiment of the present invention, step S6 includes: step S61, obtaining the effective height and effective width of the crossbeam according to the design drawings of the bridge structure; step S62, determining the stress of the crossbeam in the current jacking monitoring cycle according to the effective height, the effective width, the pressure data and the first distance.

[0043] According to one embodiment of the present invention, the total height of the transverse diaphragm is obtained based on the design drawings of the bridge structure. The thickness e of the protective layer of the main tension reinforcement and the diameter d of the main tension reinforcement, with an effective height of [missing information]. The effective width is the minimum of the following three values: 1 / 3 of the main beam span, the clear distance between adjacent beam ribs plus the beam rib width, or 12 times the flange plate thickness plus the beam rib width. The clear distance between adjacent beam ribs is... The horizontal distance between two adjacent beam ribs (e.g., a main beam) is calculated as the distance between the centerlines or edges of the two ribs minus the width of the beam rib. Then, the net distance between adjacent beam ribs is added to the beam rib width b (the width of the beam rib itself). That is, the net distance between adjacent beam ribs plus the beam rib width and the flange thickness. 12 times the beam rib width b, i.e. This is 12 times the thickness of the flange plate plus the width of the beam rib. The stress in the diaphragm represents the bending stress experienced by the diaphragm during jacking and load transfer.

[0044] According to one embodiment of the present invention, determining the stress of the crossbeam in the current jacking monitoring cycle based on the effective height, the effective width, the pressure data, and the first distance includes: determining the stress of the crossbeam in the current jacking monitoring cycle according to formula (2). ,

[0045] (2),

[0046] Where K is the load distribution correction factor. Let L be the pressure data of the i-th jack, L be the first distance, B be the effective width of the crossbeam, H be the effective height of the crossbeam, n be the number of jacks, i ≤ n, and i and n are both positive integers.

[0047] According to an embodiment of the present invention, in formula (2), Let be the product of the pressure data of the i-th jack and the first distance, representing the bending moment exerted by the i-th jack on the crossbeam. To sum the bending moments of all jacks acting on the crossbeam, i.e. the total bending moment acting on the crossbeam, represents the bending effect of the loads transmitted from all jacks and their positions on the crossbeam. K is the load distribution correction factor, which is taken as 1.2 considering the unevenness of load distribution in actual engineering. The section modulus of the diaphragm is the product of the effective width and the square of the effective height of the diaphragm. ,therefore, This indicates the ability of the cross section of the diaphragm to resist bending deformation. The larger and taller the cross section of the diaphragm, the stronger its ability to resist bending moment. The stress of the diaphragm is obtained by multiplying the load distribution correction factor by the ratio between the total bending moment acting on the diaphragm and the diaphragm section's ability to resist bending deformation. The smaller the stress, the safer the diaphragm is under the current load.

[0048] In this way, the stress of the diaphragm can be determined by the effective height, effective width, pressure data, and first distance, and the stress state of the diaphragm during the replacement process can be quantified. This allows for the determination of when to start the next stage of jacking, reducing the risk of structural damage caused by sudden stress changes and improving the safety of the diaphragm under stress.

[0049] According to one embodiment of the present invention, in step S7, a dynamic weighing system can be installed at key locations on the bridge, such as approach roads or specific sections of the bridge deck, to measure the vehicle load data of vehicles in motion. Vehicle speed data is measured using a radar speedometer.

[0050] According to one embodiment of the present invention, in step S8, the dynamic load transfer rate of the current monitoring cycle is determined based on the vehicle load data and the speed data.

[0051] Figure 4 A flowchart for calculating the dynamic load transfer rate according to an embodiment of the present invention is shown as an example.

[0052] According to an embodiment of the present invention, step S8 includes: step S81, obtaining the average vehicle load at multiple moments in the current monitoring period based on the vehicle load data; step S82, fitting the average vehicle load at multiple moments in the current monitoring period to obtain an average vehicle load time function; step S83, obtaining the average speed at multiple moments in the current monitoring period based on the speed data; step S84, fitting the average speed at multiple moments in the current monitoring period to obtain an average speed time function; and step S85, obtaining the existing pier reaction force and elevation maintenance deviation at multiple moments in the current monitoring period. Step S86: Fit the existing pier reaction force at multiple moments in the current monitoring period to obtain the existing pier reaction force time function; Step S87: Fit the elevation maintenance deviation at multiple moments in the current monitoring period to obtain the elevation maintenance deviation time function; Step S88: Obtain the stiffness of the replaced structure and the stiffness of the original structure; Step S89: Determine the dynamic load transfer rate of the current monitoring period based on the average vehicle load time function, the average speed time function, the existing pier reaction force time function, the elevation maintenance deviation time function, the stiffness of the replaced structure, and the stiffness of the original structure.

[0053] According to one embodiment of the present invention, the interval between adjacent moments can be set to 1 minute, 2 minutes, etc., and the present invention does not limit this. For each vehicle traveling on the bridge, its load data is collected. For each moment, the load values ​​of all monitored vehicles at that moment are summed and divided by the number of vehicles to obtain the average load at that moment. Similarly, the average speed is obtained. The elevation maintenance deviation is measured using a vibrating wire reaction gauge to measure the existing pier reaction force and a total station's three-dimensional coordinate measurement method. The average vehicle load time function, average speed time function, existing pier reaction force time function, and elevation maintenance deviation time function are obtained using mathematical fitting methods. Based on the material data of the replacement structure, the stiffness of the replacement structure and the stiffness of the original structure are obtained, reflecting the structure's ability to resist deformation. By considering the impact of vehicle dynamic loads on the bridge structure, the dynamic load transfer rate is monitored to assess the severity and completeness of the load transfer from the old pier to the new replacement structure.

[0054] According to one embodiment of the present invention, the dynamic load transfer rate for the current monitoring period is determined based on the average vehicle load time function, the average speed time function, the existing pier reaction force time function, the elevation maintenance deviation time function, the stiffness of the replaced structure, and the stiffness of the original structure, including: determining the dynamic load transfer rate for the current monitoring period according to formula (3). ,

[0055] (3),

[0056] in, The time function of the existing pier column reaction force. The elevation maintenance deviation time function. Let be the average vehicle load time function. It is a function of average velocity over time. To improve the structural stiffness after replacement, The original structural stiffness is represented by T, and the monitoring cycle duration is represented by T.

[0057] According to one embodiment of the present invention, in formula (3), The rate of change of the existing pier reaction force indicates the degree of drastic change in the existing pier reaction force. For example, when a vehicle passes by, if the existing pier is still actively participating in the load, the existing pier reaction force will change rapidly and significantly. If the load has been completely transferred to the new underpinning system and the existing pier bears only a very small load, the existing pier reaction force will become very small and stable, and the rate of change of the existing pier reaction force will be close to zero. It is the integral of the rate of change of reaction force of existing piers due to dynamic load and the coupling effect of structural deformation, representing the total fluctuation energy generated by the unstable transfer of dynamic load. The smaller the total fluctuation energy, the smoother the dynamic load transfer process. The instantaneous power input to the bridge by the vehicle load. This represents the total energy input to all vehicles during the current monitoring period. It is the ratio between the total fluctuating energy caused by the unstable transfer of dynamic load and the total energy input by all vehicles. The smaller this ratio, the smoother the dynamic load transfer process. This is the ratio of the original structural stiffness to the stiffness of the replaced structure, representing the impact of the change in structural stiffness on load transfer. For example, if the new system is stiffer, it has a stronger ability to share and absorb dynamic loads, which helps reduce fluctuations in the load transfer process. and Multiplying these values ​​yields the dynamic load transfer rate. The smaller the dynamic load transfer rate, the smoother the dynamic load transfer process and the higher the completion rate of the dynamic load transfer.

[0058] In this way, the dynamic load transfer rate can be determined by comparing the internally transferred fluctuation energy with the total external input energy and taking into account stiffness changes. The quality of dynamic load transfer can be comprehensively evaluated, and the impact of vehicle dynamic loads on the bridge structure can be considered. This allows for the assessment of the stability and feasibility of the pile replacement process and improves the comprehensiveness of monitoring.

[0059] According to one embodiment of the present invention, in step S9, the dynamic load transfer status is determined based on the active bearing efficiency factor of the transverse diaphragm, the stress of the transverse diaphragm, and the dynamic load transfer rate.

[0060] Figure 5 A flowchart for determining the dynamic load transfer status according to an embodiment of the present invention is shown as an example.

[0061] According to an embodiment of the present invention, step S9 includes: step S91, if the active load-bearing efficiency factor of the crossbeam is within the range of the preset active load-bearing efficiency factor, then the active load-bearing is determined to be safe; step S92, if the ratio between the stress of the crossbeam in the current lifting monitoring cycle and the stress of the crossbeam in the previous lifting monitoring cycle is less than 5% and the stress of the crossbeam in the current lifting monitoring cycle is less than the preset stress of the crossbeam, then the next stage of lifting is started; step S93, if the dynamic load transfer rate is less than the preset dynamic load transfer rate, then the dynamic load transfer is determined to be completed.

[0062] According to one embodiment of the present invention, if the active load-bearing efficiency factor of the diaphragm is within a preset range (e.g., 0.2 to 0.8), the active load-bearing capacity is deemed safe, meaning the active load-bearing function of the diaphragm meets the design requirements and the structure is in a safe load-bearing state. If the ratio between the stress of the diaphragm in the current jacking monitoring cycle and the stress of the diaphragm in the previous jacking monitoring cycle is less than 5% and the stress of the diaphragm in the current jacking monitoring cycle is less than the preset stress of the diaphragm (e.g., 25 MPa), the next stage of jacking is initiated, meaning the stress state of the diaphragm is stable and does not exceed the limit, and the next stage of jacking operation can be initiated, improving the safety of the construction process. If the dynamic load transfer rate is less than the preset dynamic load transfer rate (e.g., 0.15), the dynamic load transfer is deemed complete, meaning the dynamic load has been fully transferred from the existing pier to the new support structure, the original structure has been basically unloaded, and the transfer process has achieved the design objective.

[0063] According to an embodiment of the present invention, the dynamic load monitoring method for the pile replacement process compensates for the deflection deformation of the steel box girder by controlling the lifting displacement of the jacks, thus maintaining the original elevation of the main girder and effectively reducing the impact of bridge structural deformation caused by the replacement process on the overall stability. The active load-bearing efficiency factor and stress of the crossbeam can accurately assess the load-bearing performance of the crossbeam during the replacement process, helping to determine the safety of active load-bearing and the initiation of the next stage of jacking. By considering the impact of vehicle dynamic loads on the bridge structure and monitoring the dynamic load transfer rate, the stability and feasibility of the pile replacement process can be assessed, improving the comprehensiveness of monitoring. When determining the active load-bearing efficiency factor of the crossbeam, it can be determined through the dead load of the bridge superstructure, the maximum allowable deflection of the steel box girder, the jacking force, and the lifting displacement, thereby assessing the load-bearing performance of the crossbeam during the replacement process, promptly understanding whether the load-bearing state of the crossbeam is within a reasonable range, and improving the safety of jacking. When determining the stress of the crossbeam, the effective height, effective width, pressure data, and initial distance can be used to determine the stress state of the crossbeam during the replacement process. This quantifies the stress state of the crossbeam during the replacement process, thereby determining the initiation of the next stage of jacking, reducing the risk of structural failure due to sudden stress changes, and improving the safety of the crossbeam under load. When determining the dynamic load transfer rate, it can be based on comparing the internally transferred fluctuation energy with the total external input energy, and considering stiffness changes. This allows for a comprehensive evaluation of the dynamic load transfer quality, taking into account the impact of vehicle dynamic loads on the bridge structure, thereby assessing the stability and feasibility of the pile replacement process and improving the comprehensiveness of monitoring.

[0064] Figure 6An exemplary block diagram of a dynamic load monitoring system for the foundation pile replacement process according to an embodiment of the present invention is shown. The system includes: a jack array module for establishing a mechanical model of a four-span continuous beam, arranging a distributed jack array between the main beam and the steel box girder of the bridge to be replaced, wherein each jack in the jack array is equipped with a displacement sensor and a pressure sensor; a jacking force and jacking displacement module for compensating for the deflection deformation of the steel box girder by controlling the jacking displacement of the jacks, so that the main beam maintains its original elevation, and acquiring the jacking force and jacking displacement of the jack array in the current jacking monitoring cycle; a pressure data module for acquiring the pressure data of each jack; and an active bearing efficiency factor module for calculating the jacking force and jacking displacement based on the jacking force and jacking displacement. The system comprises the following modules: a displacement module to determine the active load-bearing efficiency factor of the diaphragm during the current lifting monitoring cycle; a first distance module to obtain the first distance between each jack; a stress module to determine the stress of the diaphragm during the current lifting monitoring cycle based on the pressure data and the first distance; a vehicle load data and speed data module to monitor the vehicle load data and speed data of multiple vehicles on the bridge during the current lifting monitoring cycle; a dynamic load transfer rate module to determine the dynamic load transfer rate during the current lifting monitoring cycle based on the vehicle load data and the speed data; and a dynamic load transfer status module to determine the dynamic load transfer status based on the active load-bearing efficiency factor of the diaphragm, the stress of the diaphragm, and the dynamic load transfer rate.

[0065] This invention can be a method, apparatus, system, and / or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for performing various aspects of the invention.

[0066] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments, and any variations or modifications may be made to the implementation of the present invention without departing from the stated principles.

Claims

1. A method for monitoring dynamic loads during pile underpinning, characterized in that, include: A mechanical model of a four-span continuous beam was established. A distributed array of jacks was arranged between the main beam and the steel box girder of the bridge to be supported. Each jack in the array was equipped with a displacement sensor and a pressure sensor. The lifting displacement of the jacks was controlled to compensate for the deflection deformation of the steel box girder, so that the main beam maintained its original elevation. The lifting force and lifting displacement of the jack array in the current lifting monitoring cycle were obtained. The pressure data of each jack were obtained. Based on the lifting force and lifting displacement, the active bearing efficiency factor of the transverse diaphragm in the current lifting monitoring cycle was determined. The first distance between each jack was obtained. Based on the pressure data and the first distance, the stress of the transverse diaphragm in the current lifting monitoring cycle was determined. During the current lifting monitoring cycle, the vehicle load data and speed data of multiple vehicles on the bridge were monitored. Based on the vehicle load data and the speed data, the dynamic load transfer rate in the current lifting monitoring cycle was determined. Based on the active bearing efficiency factor of the transverse diaphragm, the stress of the transverse diaphragm, and the dynamic load transfer rate, the dynamic load transfer status was determined. Based on the lifting force and the lifting displacement, the active bearing efficiency factor of the transverse diaphragm in the current lifting monitoring cycle is determined, including: obtaining the dead load of the bridge superstructure and the maximum allowable deflection of the steel box girder; and determining the active bearing efficiency factor of the transverse diaphragm in the current lifting monitoring cycle based on the dead load of the bridge superstructure, the maximum allowable deflection of the steel box girder, the lifting force, and the lifting displacement. Based on the dead load of the bridge superstructure, the maximum allowable deflection of the steel box girder, the jacking force, and the jacking displacement, the active bearing efficiency factor of the transverse diaphragm in the current jacking monitoring cycle is determined, including: according to the formula: Determine the active load-bearing efficiency factor of the transverse diaphragm during the current jacking monitoring cycle. ,in, The lifting force of the jack array, Let be the lifting displacement of the i-th jack. This refers to the dead load on the bridge superstructure. Let be the maximum allowable deflection of the steel box girder, n be the number of jacks, i ≤ n, and i and n are both positive integers.

2. The method for monitoring dynamic loads during pile underpinning as described in claim 1, characterized in that, Determining the stress of the crossbeam in the current jacking monitoring cycle based on the pressure data and the first distance includes: obtaining the effective height and effective width of the crossbeam according to the bridge structure design drawings; and determining the stress of the crossbeam in the current jacking monitoring cycle based on the effective height, the effective width, the pressure data, and the first distance.

3. The method for monitoring dynamic loads during pile underpinning as described in claim 2, characterized in that, Based on the effective height, the effective width, the pressure data, and the first distance, the stress of the transverse diaphragm in the current lifting monitoring cycle is determined, including: according to the formula: Determine the stress of the crossbeam during the current jacking monitoring cycle. Where K is the load distribution correction factor. Let L be the pressure data of the i-th jack, L be the first distance, B be the effective width of the crossbeam, H be the effective height of the crossbeam, n be the number of jacks, i ≤ n, and i and n are both positive integers.

4. The method for monitoring dynamic loads during pile underpinning as described in claim 3, characterized in that, Based on the vehicle load data and the speed data, the dynamic load transfer rate for the current lifting monitoring cycle is determined, including: obtaining the average vehicle load at multiple moments in the current lifting monitoring cycle based on the vehicle load data; fitting the average vehicle load at multiple moments in the current lifting monitoring cycle to obtain an average vehicle load time function; obtaining the average speed at multiple moments in the current lifting monitoring cycle based on the speed data; fitting the average speed at multiple moments in the current lifting monitoring cycle to obtain an average speed time function; obtaining the existing pier reaction force and elevation maintenance deviation at multiple moments in the current lifting monitoring cycle; fitting the existing pier reaction force at multiple moments in the current lifting monitoring cycle to obtain an existing pier reaction force time function; fitting the elevation maintenance deviation at multiple moments in the current lifting monitoring cycle to obtain an elevation maintenance deviation time function; obtaining the stiffness of the structure after replacement and the stiffness of the original structure; and determining the dynamic load transfer rate for the current lifting monitoring cycle based on the average vehicle load time function, the average speed time function, the existing pier reaction force time function, the elevation maintenance deviation time function, the stiffness of the structure after replacement, and the stiffness of the original structure.

5. The method for monitoring dynamic loads during pile underpinning as described in claim 4, characterized in that, Based on the average vehicle load time function, the average speed time function, the existing pier reaction force time function, the elevation maintenance deviation time function, the stiffness of the replaced structure, and the stiffness of the original structure, the dynamic load transfer rate for the current jacking monitoring cycle is determined, including: according to the formula: Determine the dynamic load transfer rate for the current jacking monitoring cycle. ,in, The time function of the existing pier column reaction force. The elevation maintenance deviation time function. Let be the average vehicle load time function. It is a function of average velocity over time. To improve the structural stiffness after replacement, The original structural stiffness is represented by T, and the jacking monitoring cycle duration is represented by T.

6. The method for monitoring dynamic loads during pile underpinning as described in claim 5, characterized in that, The dynamic load transfer status is determined based on the active load-bearing efficiency factor of the crossbeam, the stress of the crossbeam, and the dynamic load transfer rate, including: if the active load-bearing efficiency factor of the crossbeam is within a preset active load-bearing efficiency factor range, then the active load is deemed safe; if the ratio between the stress of the crossbeam in the current jacking monitoring cycle and the stress of the crossbeam in the previous jacking monitoring cycle is less than 5% and the stress of the crossbeam in the current jacking monitoring cycle is less than the preset stress of the crossbeam, then the next stage of jacking is initiated; if the dynamic load transfer rate is less than the preset dynamic load transfer rate, then the dynamic load transfer is deemed complete.

7. A dynamic load monitoring system for pile underpinning process, used to execute the dynamic load monitoring method for pile underpinning process as described in any one of claims 1-6, characterized in that, include: The jack array module is used to establish a mechanical model of a four-span continuous beam. A distributed jack array is arranged between the main beam and the steel box girder of the bridge to be supported. Each jack in the array is equipped with a displacement sensor and a pressure sensor. The jacking force and jacking displacement module is used to compensate for the deflection deformation of the steel box girder by controlling the jacking displacement of the jacks, maintaining the original elevation of the main beam, and acquiring the jacking force and jacking displacement of the jack array during the current jacking monitoring cycle. The pressure data module is used to acquire the pressure data of each jack. The active bearing efficiency factor module is used to determine the active bearing capacity of the transverse diaphragm during the current jacking monitoring cycle based on the jacking force and the jacking displacement. The system includes: a load-bearing efficiency factor; a first distance module for obtaining the first distance between each jack; a stress module for determining the stress of the crossbeam in the current jacking monitoring cycle based on the pressure data and the first distance; a vehicle load data and speed data module for monitoring the vehicle load data and speed data of multiple vehicles on the bridge in the current jacking monitoring cycle; a dynamic load transfer rate module for determining the dynamic load transfer rate in the current jacking monitoring cycle based on the vehicle load data and the speed data; and a dynamic load transfer status module for determining the dynamic load transfer status based on the active load-bearing efficiency factor of the crossbeam, the stress of the crossbeam, and the dynamic load transfer rate.

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