A method and system for measuring the force on a non-permanent casing based on a mechanical sensor

Abstract

This invention relates to the field of mechanical sensor technology, providing a method and system for measuring the force on a non-permanent casing based on mechanical sensors. The method includes: placing corresponding equipment at the core location, the pressure location, and the cable burial location; converting the collected microvolt-level analog signals into digital electrical frequency bands; providing digital mechanical evidence to verify the buckling and tear resistance of the single-sided open-closed casing during the pressing stage when it is pressed into soft strata by a pile driver while the casing remains closed; achieving dynamic monitoring of fluid-solid balance during the borehole dredging and concrete pouring stages; automatically outputting electronic commands to reach the optimal demolding and pull-out critical point in the later stage of concrete pouring; and responding to the electronic commands. Specifically, this invention relates to a special sensor concealed deployment architecture for full life-cycle force monitoring of single-sided open-closed ultra-long temporary casings for cast-in-place piles in weak or soft soil, and measurement and evaluation based on electrical digital inflection point determination.

Description

Technical Field

[0001] This invention relates to the field of mechanical sensor technology, and in particular to a method and system for measuring the force on a non-permanent casing based on mechanical sensors. Background Technology

[0002] During underwater cast-in-place pile construction, the use of non-permanent single-sided opening and closing casings can effectively eliminate the frictional resistance of the pipe wall during casing removal. In deep water and deep soft mud environments, the casing construction process is significantly invisible and uncontrollable. Specifically, in the multiple construction stages of high-frequency vibration pressing with hundreds of tons of excitation force, scouring and holding the load inside the casing, underwater high-flowability concrete pouring, and finally the opening and removal of the casing, the weak parts of the casing structure, such as the spliced ​​sections, reverse labyrinth teeth, and external reinforcing plates, are subjected to highly uncertain compressive forces and huge shear stresses.

[0003] Due to the lack of a sensor monitoring network capable of surviving and operating stably in extreme abrasion and harsh underwater environments, construction personnel are unable to obtain the true mechanical parameters inside the casing. This results in: the inability to verify the structural safety of the combined flexible casing in real time during construction; a lack of quantifiable electrical data to determine the timing of casing removal; if removal is too early, the insufficiently hardened concrete will flow, leading to hole collapse; if removal is too late, a strong bond will form between the casing wall and the hardened cement slurry, making removal difficult or even impossible.

[0004] Therefore, there is an urgent need to propose a technical solution that can monitor the stress state of key parts of a single-sided opening and closing casing in real time and optimize the timing of extraction based on the monitoring data, so as to solve the safety risks and process control problems caused by the lack of basis for operation in the existing construction process. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for measuring the force on a non-permanent casing based on a mechanical sensor, comprising: The core location, extrusion pressure location, and cable burial location of the single-sided opening and closing casing are obtained; corresponding equipment is placed at the core location, extrusion pressure location, and cable burial location, and the wireless data acquisition terminal acquires the acquisition signals of the equipment; During the pressing stage, the equipment continuously acquires circumferential tangential strain data at the root of the labyrinth tooth in the spliced ​​section of the single-sided opening and closing casing using a high-frequency dynamic acquisition method, as well as the earth pressure map of the outer wall of the single-sided opening and closing casing; providing digital mechanical evidence to verify the buckling resistance and tear resistance of the single-sided opening and closing casing. During the load-bearing phase, the equipment collects and compares earth pressure and lateral expansion pressure in real time. In the later stages of concrete pouring, the radial compressive stress curve inside the single-sided open and closed casing is tracked; electronic commands are automatically output to reach the optimal demolding and pull-out critical point. Responding to electronic commands, the data spectrum of the readings of the dual-diaphragm vibrating wire micro earth pressure gauge and the circumferential strain gauge shows a precipitous drop, and the transient negative pulse pressure difference unloading electrical data is acquired and stored for the ultimate verification of the unloading and friction reduction effects of the single-sided opening and closing casing.

[0006] Optionally, the core location is the recessed area at the root of the tooth groove in the labyrinth structure of the inner slotted splicing section, and the blind area at the junction of the inner and outer sides of the 16mm thick reinforcing plate. The core location is used to install resistance strain gauges or thin-film shear force sensors, which are installed by spot welding or high-strength epoxy resin embedding. The extrusion pressure location is on the surface of the reinforcing plate wing outside the standard segment of the casing. The extrusion pressure location is installed by embedding a dual-diaphragm vibrating wire micro earth pressure gauge that is resistant to high-frequency vibration through holes along the elevation gradient. This is used to sense the total water and soil encapsulation extrusion pressure of the surrounding silt layers at different depths.

[0007] Optionally, the cable is buried at the edge of the reinforcing plate where angle steel is welded to form a longitudinally enclosed flow-guiding and protective steel trough that runs through the axial direction; the data lines of all sensors are introduced into the longitudinally enclosed flow-guiding and protective steel trough and lead upward to the water surface; the cable terminus is connected to an anti-vibration and anti-splash wireless data acquisition terminal arranged below the support plate at the top of the single-sided open and closed casing, which converts the microvolt-level analog signal into a digital electrical frequency band and transmits it to the host computer monitoring and control platform via a wireless network.

[0008] Optionally, the process of automatically outputting electronic instructions to reach the optimal demolding and pull-out critical point includes the following steps: The pressure values ​​output by the radial compressive stress sensor inside the casing are continuously collected at fixed time intervals, and the pressure values ​​collected each time are stored in a first-in-first-out buffer sequence. When the number of pressure values ​​stored in the buffer sequence reaches the preset window length, the difference between two adjacent pressure values ​​is calculated and divided by the time interval from the end of the buffer sequence to obtain a set of instantaneous first derivative values. The set of instantaneous first derivative values ​​are sorted from largest to smallest, and the value in the middle position after sorting is taken as the reference slope of the current window. Each instantaneous first derivative value is divided by the reference slope to obtain a normalized slope sequence. The change pattern in the normalized slope sequence, from a group of values ​​greater than the first normalization threshold to a group of values ​​less than the second normalization threshold and then negative values, is a visual representation of the inflection point of the characteristic signal. The positions in the normalized slope sequence where three or more consecutive negative values ​​appear are marked as candidate inflection point positions. Then, all instantaneous values ​​of the first derivative within a time interval are extracted from the candidate inflection point positions. The difference between the maximum and minimum values ​​of all instantaneous values ​​of the first derivative is calculated as the slope change amplitude. When the slope change amplitude is greater than a preset amplitude threshold, the candidate inflection point position is confirmed as the characteristic signal attenuation inflection point, and the absolute time value corresponding to the candidate inflection point is recorded. The absolute time value is compared with the initial and final freezing time points in the underwater freezing test data under the same conditions: if the absolute time value is after the initial freezing time point and the difference between it and the final freezing time point is greater than a preset hysteresis threshold, then the calculation kernel generates an electronic instruction.

[0009] Optionally, the process of setting a preset amplitude threshold includes the following steps: From the circumferential tangential strain data recorded during the pressing stage, each strain value is sequentially extracted and compared with the pre-stored yield strength strain value of the casing material. After traversing all strain values, if at least one strain value is greater than the yield strength strain value, the first judgment flag is set to high level; otherwise, it is set to low level. From the earth pressure map of the silt layer outside the casing recorded during the load-bearing stage, the stable readings output by the earth pressure gauges at different elevations before concrete pouring are extracted. The stable readings are retrieved sequentially according to the storage order. Starting from the second reading, the difference between the current reading and the previous reading is calculated, and the absolute value of the difference is taken. After traversing all adjacent reading pairs, the maximum value among the absolute values ​​is found. The maximum value is compared with the preset stability threshold. If the maximum value is greater than the stability threshold, the second judgment flag is set to high level; otherwise, it is set to low level. The first and second decision flags are combined into a two-bit binary value in the order of high level followed by low level. Based on the binary value, the amplitude threshold at the corresponding position is selected from a predefined sequence containing four amplitude thresholds: the first amplitude threshold is selected when the binary value is zero, the second amplitude threshold is selected when the binary value is zero, the third amplitude threshold is selected when the binary value is one, and the fourth amplitude threshold is selected when the binary value is one. The selected amplitude threshold is used as the final output result, thus completing the setting of the amplitude threshold.

[0010] Optionally, the process of extracting stable readings from earth pressure gauges at different elevations before concrete pouring includes the following steps: Locate the data frame corresponding to the start of concrete pouring from the earth pressure spectrum, and take all data frames within one complete vibration cycle preceding this data frame as the extraction interval; for each earth pressure gauge, arrange the pressure values ​​output within the extraction interval into a sequence according to the acquisition time; scan backward from the beginning of the sequence to find the pressure value with the most consecutive repetitions; if multiple pressure values ​​have the same number of consecutive repetitions, take the first pressure value that appears as the initial stable reading of the earth pressure gauge; The preliminary stable readings output by all earth pressure gauges at the same elevation are collected into a set; the number of times each reading occurs is counted, and the reading with the most occurrences is taken as the intermediate stable reading of the elevation; if there are multiple readings with the most occurrences, the readings are arranged from low to high and the one in the middle is taken as the intermediate stable reading of the elevation. The intermediate stable readings at each elevation are stored sequentially into an output sequence in ascending order of elevation. Starting from the second element of the output sequence, the current element is checked against the previous element. If they are not equal, the current element is retained; if they are equal, the current element is deleted and subsequent elements are shifted forward. After all checks are completed on the output sequence, the final sequence is used as the stable reading sequence output by the earth pressure gauges at different elevations before concrete pouring.

[0011] Optionally, the process of the computation kernel generating an electronic instruction includes the following steps: From the cache location corresponding to the confirmed characteristic signal attenuation inflection point, extract the radial compressive stress value, normalized slope value, and slope change amplitude value corresponding to the characteristic signal attenuation inflection point at the moment the characteristic signal attenuation inflection point occurs; at the same time, extract the average stable reading of earth pressure gauges at all different elevations within the same time window corresponding to the characteristic signal attenuation inflection point from the earth pressure map outside the casing; write the extracted radial compressive stress value, normalized slope value, slope change amplitude value, and average earth pressure value into a temporary data storage area in a preset field order to form the original instruction data block; The starting and ending condensation times are read from the underwater condensation test data under the same conditions. The absolute time value of the characteristic signal attenuation inflection point and the time difference between the starting condensation time are calculated. The time difference is compared with the preset lower and upper limits of the allowable takeoff time window: if the time difference is greater than or equal to the lower limit and less than or equal to the upper limit, the takeoff permission flag is set to the first value; if the time difference is less than the lower limit or greater than the upper limit, the takeoff permission flag is set to the second value. The takeoff permission flag is appended to the end of the original command data block to obtain the expanded command data block. The normalized slope value and slope change amplitude value at the inflection point of the characteristic signal attenuation are combined. According to the preset feature code generation rules, the two decimal places of the normalized slope value are concatenated with the first two digits of the integer part of the slope change amplitude value to obtain a four-digit feature code. The four-digit feature code is written into the starting position of the extended instruction data block. The complete instruction data block, which includes the feature code, radial compressive stress value, normalized slope value, slope change amplitude value, average earth pressure, and pull-out permission flag, is sent out sequentially through the output port of the wireless data acquisition terminal to form an electronic instruction.

[0012] Optionally, the process of obtaining a four-digit feature code includes the following steps: Convert the normalized slope value into a string, scan from the beginning of the string to find the position of the decimal point character; starting from the next character after the position, take out two characters in sequence as the first character pair; if there is only one character after the decimal point, add a zero character after that character to form the first character pair; if there is no character after the decimal point, directly take two zero characters as the first character pair. Convert the slope change value into a string. Starting from the beginning of the string, extract characters sequentially until a decimal point is encountered or the end of the string is reached. Collect all extracted characters as the integer part string. Starting from the beginning of the integer part string, extract two characters sequentially to form the second character pair. If the length of the integer part string is one, add a zero character after the characters to form the second character pair. If the integer part string is empty, directly extract two zero characters as the second character pair. Write the first character pair and the second character pair into a buffer of length four characters in the order of first character pair then second character pair, so that the first two characters in the buffer are the first character pair and the last two characters are the second character pair; output the four characters in the buffer as a whole as a four-digit feature code.

[0013] Optionally, the process of acquiring and storing transient negative pulse differential pressure unloading electrical data includes the following steps: At the same moment that the top tensioning device receives the electronic command and begins to release downwards, the output values ​​of the dual-diaphragm vibrating wire micro earth pressure gauge and the output values ​​of the circumferential strain gauge are read sequentially; and each pair of output values ​​read, along with the sequential number of that read, is stored in a pre-allocated storage area. The earth pressure values ​​read from two consecutive intervals are retrieved sequentially from the storage area, and the decrease in the value of the latter interval relative to the former interval is calculated. When two consecutive decreases are greater than the decrease threshold value set in advance based on the opening width of the casing, the corresponding time is marked as the start time of the negative pulse. Values ​​are read from the start time of the negative pulse until the maximum difference between three consecutive earth pressure values ​​is less than the stability threshold value set in advance based on the stable state after the opening of the casing expansion joint. All value pairs between the start time of the negative pulse and the stable time are extracted to form a transient data sequence. The earth pressure and circumferential strain values ​​of each numerical pair in the transient data sequence are arranged in chronological order, and the identification number of the current casing and the system time of the start-up of the top tensioning device are appended to the beginning of the transient data sequence. The entire transient data sequence with the appended identification number and system time is stored in a storage device with power-off retention function to complete the acquisition and storage of transient negative pulse pressure difference unloading electrical data.

[0014] This invention provides a force measurement system for non-permanent casings based on mechanical sensors, used to implement the aforementioned force measurement method for non-permanent casings based on mechanical sensors, comprising: The equipment deployment module is used to obtain the core position, extrusion pressure position and cable burial position of the single-sided opening and closing casing; the corresponding equipment is placed at the core position, extrusion pressure position and cable burial position, and the wireless data acquisition terminal obtains the acquisition signal of the equipment and converts the microvolt-level analog signal of the acquisition signal into digital electrical frequency band. The strain data acquisition module is used during the driving stage when the single-sided open-closed casing is pressed into the soft stratum by the pile driver while the casing remains closed. The equipment continuously acquires the circumferential tangential strain data of the labyrinth tooth root in the spliced ​​section of the single-sided open-closed casing and the earth pressure spectrum of the outer wall of the single-sided open-closed casing using a high-frequency dynamic acquisition method. When a sharp increase in local stress is detected and it approaches the yield limit of the material, an audible, visual and electrode value alarm signal is issued to indicate that the pile driving should be suspended or the pile driving posture should be adjusted. The pressure monitoring module is used to collect and compare the following two types of pressure data in real time during the borehole dredging and concrete pouring load-bearing stages: the soil pressure corresponding to the depth of the silt layer outside the single-sided open and closed casing, and the flow lateral expansion pressure generated by the gradual accumulation of concrete inside the single-sided open and closed casing. The signal inflection point confirmation module is used to track the radial compressive stress curve inside the single-sided open-closed casing in the later stage of concrete pouring. As the concrete undergoes a hydration, gelation, and solidification phase transition, it transforms from a fluid state to a plastic solid state. After the lateral outward expansion water pressure reaches its extreme value, physical shrinkage occurs, causing the radial compressive stress curve recorded by the equipment to exhibit a characteristic signal inflection point where the slope of the first derivative changes from steep to gentle and then decreases. After the kernel captures the characteristic signal attenuation inflection point, it automatically outputs an electronic command to reach the optimal demolding and pull-out critical point by combining the comparison data from underwater solidification tests under the same conditions. The instruction execution module is used to respond to electronic instructions, start the top tensioning device to release downwards, so that the single-sided opening and closing casing opens along the inclined groove to form a diameter expansion micro-shrinkage joint; at the same time, it records the data spectrum of the readings of the double diaphragm vibrating wire micro earth pressure gauge and the circumferential strain gauge, which shows a cliff-like step drop, and acquires and stores the transient negative pulse pressure difference unloading electrical data, which is used to ultimately verify the unloading and friction reduction effects of the single-sided opening and closing casing.

[0015] This invention ensures structural safety and process controllability throughout the entire casing construction process through multi-parameter synchronous sensing, real-time early warning, and closed-loop control, and provides reliable data support for optimized design. This invention utilizes a concealed sensor matrix to deploy in blind spots within the casing's geometry to acquire high-fidelity electromechanical data; it verifies the ultimate mechanical redundancy of specially opened casings through real-time digital monitoring; and it innovatively utilizes the rate of change of structural mechanical signals or inflection points of electrical characteristics to automatically determine the optimal demolding and extraction timing.

[0016] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a block diagram of the non-permanent casing force measurement method based on a mechanical sensor in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the force measurement method for non-permanent casing based on a mechanical sensor in Embodiment 1 of the present invention. Figure 3 This is a diagram illustrating the process of converting the microvolt-level analog signal of the acquired signal into a digital electrical frequency band in Embodiment 2 of the present invention. Figure 4 This is a process diagram of automatically outputting electronic instructions to reach the optimal demolding and pulling-out critical point in Embodiment 4 of the present invention; Figure 5 This is a process diagram of acquiring and storing transient negative pulse differential pressure unloading electrical data in Embodiment 9 of the present invention; Figure 6 This is a flowchart of the force measurement system for a non-permanent casing based on a mechanical sensor in Embodiment 10 of the present invention. Detailed Implementation

[0019] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms "a," "say," and "this" used in the embodiments of this application are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms used herein refer to and / or include any or all possible combinations of one or more associated listed items.

[0021] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application. In the description of this application, it should be understood that the terms first, second, third, etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0022] Example 1: As Figure 1 As shown, this embodiment of the invention provides a method for measuring the force on a non-permanent casing based on a mechanical sensor, comprising: S100: Obtain the core position, extrusion pressure position, and cable burial position of the single-sided opening and closing casing; place the corresponding equipment at the core position, extrusion pressure position, and cable burial position; the wireless data acquisition terminal obtains the acquisition signal of the equipment and converts the microvolt-level analog signal of the acquisition signal into a digital electrical frequency band. The core area consists of the recessed area at the root of the groove in the labyrinth structure of the inner slotted splicing section, and the blind area at the junction of the inner and outer sides of the 16mm thick reinforcing plate. The core area is used to install resistance strain gauges or thin-film shear force sensors, which are installed by spot welding or high-strength epoxy resin embedding. The extrusion pressure position is on the side wing surface of the reinforcing plate around the standard section of the casing. The extrusion pressure position is where a double-diaphragm vibrating wire micro earth pressure gauge, which is resistant to high-frequency vibration, is embedded in the opening along the elevation gradient to accurately sense the total water and soil encapsulation extrusion pressure of the surrounding silt layer at different depths. The cable burial position is formed by welding angle steel to the side edge of the reinforcing plate to form a longitudinally enclosed flow-guiding and protective steel channel that runs through the axial direction. The data lines of all sensors are introduced into the longitudinally enclosed flow-guiding and protective steel channel to reach the water surface, preventing them from being cut by underground hard objects. The cable terminus is connected to a shock-resistant and splash-proof wireless data acquisition terminal located under the support plate at the top of the single-sided open and closed casing. This terminal converts the microvolt-level analog signal into a digital electrical frequency band and transmits it to the host computer monitoring and control platform via a wireless network. S200: During the driving stage when the single-sided open-closed casing is pressed into the soft stratum by the pile driver while the casing remains closed, the equipment continuously acquires the circumferential tangential strain data of the labyrinth tooth root in the spliced ​​section of the single-sided open-closed casing and the earth pressure map of the outer wall of the single-sided open-closed casing using a high-frequency dynamic acquisition method; when a sharp increase in local stress is detected and it approaches the yield limit of the material, an audible, visual and electrode value alarm signal is issued to indicate the suspension of pile driving or adjustment of the pile driving posture, providing digital mechanical evidence to verify the buckling resistance and tear resistance of the single-sided open-closed casing; S300: During the load-bearing stage of drilling dredging and concrete pouring, the equipment collects and compares the following two types of pressure data in real time: the soil pressure corresponding to the deep silt layer outside the single-sided open and closed casing, and the expansion pressure of the flow side generated by the gradual accumulation of concrete inside the single-sided open and closed casing, so as to realize dynamic monitoring of fluid-solid balance. S400: In the later stage of concrete pouring, the radial compressive stress curve inside the single-sided open and closed casing is tracked; as the concrete hydration gel solidification phase transition occurs, the concrete changes from a fluid state to a plastic solid state. After the lateral outward expansion water pressure reaches its extreme value, physical shrinkage occurs, causing the radial compressive stress curve recorded by the equipment to show a characteristic signal inflection point where the slope of the first derivative changes from steep to gentle and then decreases; after calculating the inflection point of the characteristic signal attenuation captured by the kernel, combined with the comparison data of the underwater solidification test under the same conditions, the electronic command to reach the optimal demolding and pull-out critical point is automatically output. S500: Responding to electronic commands, the top tensioning device is activated to release downwards, causing the single-sided opening and closing casing to open along the inclined groove to form a micro-contraction joint; at the same time, the readings of the dual-diaphragm vibrating wire micro earth pressure gauge and the circumferential strain gauge are recorded, showing a data spectrum of a cliff-like step drop, and the transient negative pulse pressure difference unloading electrical data are acquired and stored for the ultimate verification of the unloading and friction-reducing effects of the single-sided opening and closing casing.

[0023] Among them, the microvolt-level analog signal refers to the raw electrical or optical analog signal directly output by sensors such as fiber optic microstrain gauges, thin-film shear force sensors, and dual-diaphragm vibrating wire earth pressure gauges, with an amplitude typically in the microvolt range. This signal is highly susceptible to environmental noise, high-frequency vibration, and attenuation over long distances. By installing a wireless data acquisition terminal at the top of the casing, the microvolt-level analog signal is converted into a digital signal locally, ensuring the original fidelity and identifiability of the force monitoring data under harsh conditions such as deep water, strong vibration, and silt abrasion. The digital electrical frequency band refers to the digital signal generated after the microvolt-level analog signal is amplified, filtered, and converted from analog to digital by the data acquisition terminal. It is transmitted to the host computer via a wireless network using specific communication frequency bands, such as 2.4 GHz and 433 MHz (industrial, scientific, and medical frequency bands). This conversion process frees the weak mechanical signal from attenuation and interference caused by long-distance wired transmission, forming the basis for real-time force monitoring, remote early warning, and closed-loop control of the casing. The single-sided opening and closing casing is an auxiliary device for the construction of non-permanent underwater cast-in-place piles. Its casing wall is slit along the axial direction and equipped with reverse labyrinth teeth, external reinforcing plates and inclined groove tensioning mechanisms. It can be pressed into the stratum in the closed state and opened after the concrete has initially set to eliminate the pull-out friction. The casing itself serves as a carrier for stress monitoring. Its slit splice section, labyrinth tooth root, and reinforcing plate junction area are all mechanically weak or stress-concentrated areas, thus becoming the core locations for sensor deployment. The stress monitoring of the casing is essentially a safety verification of its non-permanent characteristics - that is, monitoring its structural response throughout the entire process of closing, holding load, and opening to ensure that it can be reused or safely removed. The driving stage refers to the construction phase in which the casing is gradually penetrated into the soft strata by the pile driver in a closed state using high-frequency vibration or static pressure. The casing wall is subjected to huge axial excitation force, circumferential extrusion force and lateral pressure of the soil. The labyrinth teeth and spliced ​​sections are at risk of buckling or tearing. The core task of stress monitoring during the driving stage is to capture abnormal increases in circumferential tangential strain and soil pressure in real time, issue early warnings before the material yields, provide quantitative mechanical evidence for adjusting the pile driving posture, and directly verify the buckling resistance and tear resistance of the casing. High-frequency dynamic acquisition refers to continuously recording the changes in sensor signals at a sampling frequency of not less than 100 Hz, typically 200–1000 Hz. Because the excitation frequency of pile drivers is high, usually 20–40 Hz, and stress concentration can reach its peak within milliseconds, conventional low-frequency acquisition cannot capture the risk of instantaneous yielding. High-frequency dynamic acquisition ensures that the stress extreme values ​​in each vibration cycle during the compaction stage are recorded, which is the technical prerequisite for safety early warning of compaction failure and the basis for the time resolution of generating circumferential tangential strain data and earth pressure maps.Circumferential tangential strain data refers to the linear strain measured by strain sensors deployed in the recessed area at the root of the labyrinth tooth, along the tangential direction of the casing circumference. It reflects the degree of circumferential expansion or contraction deformation of the jointed section under soil compression and vibration. Circumferential tangential strain data is a core indicator for determining whether the casing is close to the material's yield limit, and it is also direct mechanical evidence for evaluating the closing and locking effect and tear resistance safety margin of a single-sided open-close casing. Earth pressure map refers to the distribution map of total soil and water pressure measured by earth pressure sensors arranged at different elevations and circumferential positions along the outer wall of the casing. It can be represented as a three-dimensional time-depth-pressure map or a contour map. It not only reflects the static wrapping pressure of the outer silt layer on the casing, but also captures local pressure anomalies caused by deflection, impact of hard objects, etc. during the pressing process. The earth pressure map and circumferential tangential strain data corroborate each other: a sudden increase in local earth pressure usually leads to an increase in circumferential strain at the corresponding location, thus constituting a dual criterion for early warning of pressing failure. The load-bearing stage refers to the construction stage from the completion of casing insertion, internal drilling and dredging, and the start of underwater concrete pouring until the initial setting of the concrete. The casing is simultaneously subjected to the earth pressure of the thick soft mud or long-term static load on the outside and the lateral expansion pressure or dynamic increasing load of the highly fluid concrete inside. The goal of stress monitoring during the load-bearing stage is to achieve fluid-solid equilibrium measurement, and to compare the external earth pressure with the internal concrete lateral pressure in real time to ensure that the casing does not buckle locally or leak under asymmetric load, and to provide a steady-state stress baseline for judging the timing of extraction. The earth pressure corresponding to the deep silt layer outside the single-sided opening and closing casing, and the lateral expansion pressure generated by the gradual accumulation of concrete inside the single-sided opening and closing casing, are compared. The former refers to the total water and soil pressure measured by earth pressure gauges at different depths on the outer wall of the casing, the magnitude of which depends on the soil depth, unit weight, and degree of casing penetration disturbance; the latter refers to the dynamic pressure of fresh concrete on the sidewall of the casing measured by radial compressive stress sensors on the inner side of the casing, such as thin-film pressure sensors or fiber optic strain gauges attached to the inner wall. The ratio or difference between the two is calculated in real time: if the internal expansion pressure exceeds the external earth pressure and reaches a set threshold, it indicates that the casing is at risk of excessive expansion; if the external earth pressure is much greater than the internal pressure, it may cause the casing to shrink or the labyrinth teeth to disengage. Comparison is a key means of verifying the structural integrity of the single-sided opening and closing casing during the load-bearing stage. The radial compressive stress curve is a continuous record of the radial pressure on the inner wall of the casing as a function of time from the start of concrete pouring to the complete initial setting. The curve starts at the peak flow pressure at the moment of concrete pouring, and then exhibits complex nonlinear changes due to cement hydration and the formation of flocculated structures. The radial compressive stress curve is the core monitoring object for determining the concrete phase transformation process and the bonding state of the casing-concrete interface. The inflection point of its slope and the inflection point of the characteristic signal are directly used to determine the optimal time for pull-out.The characteristic signal inflection point refers to the turning point where the first derivative or slope of the radial compressive stress curve changes from a positive and large value or a steep increase to a flat or near-zero slope and then turns into a negative value or a slow decrease. The physical essence of the inflection point is that when concrete changes from a fluid state to a plastic solid state, its lateral expansion pressure reaches its maximum value. Subsequently, due to chemical shrinkage and temperature drop, volume shrinkage occurs, resulting in a decrease in pressure on the inner wall of the casing. The slope change algorithm automatically identifies this inflection point and uses it as the electrical criterion for the optimal demolding and pull-out critical point, avoiding the process risks of premature hole collapse and late seizing caused by the traditional empirical method. The optimal demolding and pull-out critical point refers to the time window during which the concrete has initially solidified to form sufficient self-supporting strength, but has not yet formed significant chemical bonding or mechanical locking with the inner wall of the casing. By capturing the inflection point of characteristic signals and combining it with underwater solidification test data under the same conditions, such as the penetration resistance value measured by reserved test blocks, the electronic command corresponding to this critical point is quantitatively output. This command is the sole basis for activating the top tensioning device, realizing a scientific and data-driven decision-making process for the timing of pull-out of the non-permanent casing. The top tensioning device is a mechanical actuator installed on the top of a single-sided opening and closing casing, typically including a hydraulic cylinder or electric push rod and a inclined groove tensioning head. After receiving the optimal demolding and pull-out critical point command, it releases tension downwards, forcing the casing to open radially along the preset inclined groove, forming a micro-contraction joint with an expansion diameter, typically 2-5 mm, thereby cutting off the frictional resistance and adhesion between the inner wall of the casing and the concrete column. The timing and effect of the top tensioning device's action need to be confirmed in a closed loop through unloading and opening effect verification. The dual-diaphragm vibrating wire miniature earth pressure gauge is a miniature earth pressure sensor with a dual-diaphragm structure and built-in vibrating wire element. It features high-frequency vibration resistance, good long-term stability, and strong anti-interference capability of the output frequency signal, making it suitable for earth pressure measurement under the excitation environment of pile drivers. The circumferential strain gauge, which is a resistance strain gauge or fiber optic strain gauge, is used to measure the circumferential deformation of the casing. These two types of sensors constitute the core sensing layer of force monitoring: the earth pressure gauge provides the external load boundary conditions, and the circumferential strain gauge provides the structural response. Together, they verify the unloading effect of the casing at the moment of opening. The data spectrum refers to the pressure-time curve or strain-time curve recorded by the dual-diaphragm vibrating wire earth pressure gauge and the circumferential strain gauge at the moment of action of the top tensioning device and within a few seconds thereafter. The spectrum shows a typical cliff-like step drop - the value drops by more than 80% in a very short time, usually less than 0.5 seconds. The data spectrum is an irreplaceable empirical material for verifying the unloading effect of the single-sided opening and closing casing, and it is also the final electrical evidence for evaluating whether the casing design meets the requirement of non-permanence.Transient negative pulse pressure differential unloading electrical data refers to the transient waveform data formed when the pressure value output by the earth pressure gauge changes sharply in the negative direction at the moment the casing expands, for example, from 500 kPa to 50 kPa, while the strain value output by the circumferential strain gauge rapidly drops from a tensile state to zero or a negative value. The data appears as a steep falling edge similar to a negative pulse on the time axis. Acquiring and storing this transient negative pulse pressure differential unloading electrical data is not only used for the ultimate verification of the unloading and friction reduction effect of the single-sided opening and closing casing, but also as a quantitative basis for optimizing tensioning parameters and correcting the pull-out criteria in similar projects. The stress relief and friction reduction effects refer to the performance of a single-sided open-close casing, which, through mechanical opening, enlarges its inner diameter, and cuts off contact and adsorption with the concrete column, significantly eliminates or reduces the frictional resistance and bonding force between the outer wall of the casing and the soil, and between the inner wall and the concrete. This effect cannot be asserted solely based on design drawings or finite element analysis, but must be verified through actual monitoring data: when the top tensioning device is activated, recording the data spectrum of the cliff-like step-drop and the transient negative pulse pressure difference unloading electrical data indicates that the casing has achieved effective stress relief and friction reduction. This effect is a core technical indicator for determining whether a non-permanent casing truly possesses the advantages of non-permanent construction.

[0024] The working principle and beneficial effects of the above technical solution are as follows: (Refer to Appendix for details.) Figure 2 This embodiment achieves continuous and precise monitoring of the mechanical state of the casing structure and its interaction with the surrounding soil by integrating sensor deployment, signal acquisition, and real-time analysis. Miniature high-precision sensors are deployed at key locations on the casing, including strain monitoring points in the blind area of ​​the recessed area at the root of the labyrinthine groove and the junction of the reinforcing plate, earth pressure gauges embedded along the elevation gradient on the surface of the reinforcing plate side wings, and an integrated cable system protected by a longitudinally enclosed guide steel trough. All sensor signals are converted into digital signals by a wireless data acquisition terminal and transmitted remotely. During the casing's penetration into soft strata, the system frequently acquires circumferential tangential strain and external earth pressure data. When the local stress approaches the material's yield limit, a multi-mode alarm is triggered to guide adjustments during pile driving, providing digital verification of the casing's buckling and tear resistance performance. During the drilling, dredging, and concrete pouring stages, the system simultaneously monitors the earth pressure of the external silt layer and the lateral pressure of the internal concrete flow, achieving dynamic balance monitoring of the fluid-structure interaction. In the later stages of concrete pouring, the system tracks the changes in the radial compressive stress curve, captures the stress inflection point characteristics caused by concrete phase transformation, and, combined with underwater setting test data, automatically determines the optimal demolding and pull-out critical point and outputs control commands. Based on these commands, the system controls the tensioning device at the top of the casing to open along the inclined groove, forming a micro-contraction joint. Simultaneously, it records the step-drop data of earth pressure and circumferential strain, acquiring transient unloading pulse characteristics to fully verify the casing's stress relief and friction reduction effectiveness.

[0025] In summary, this embodiment ensures structural safety and process controllability throughout the entire casing construction process through multi-parameter synchronous sensing, real-time early warning, and closed-loop control, and provides reliable data support for optimized design. This embodiment utilizes a concealed sensor matrix to deploy at blind spots in the casing's geometry to acquire high-fidelity electromechanical data; verifies the ultimate mechanical redundancy of specially opened casings through real-time digital monitoring; and innovatively utilizes the rate of change of structural mechanical signals or inflection points of electrical characteristics to automatically determine the optimal demolding and extraction timing.

[0026] Example 2: As Figure 3 As shown, based on Example 1, the process of converting the microvolt-level analog signal of the acquired signal into a digital electrical frequency band provided by this embodiment of the invention specifically includes the following steps: Step S101: The microvolt-level analog signal output by the resistance strain gauge or thin-film shear force sensor deployed in the recessed area at the root of the maze card and the blind area at the junction of the reinforcing plate is introduced into the shockproof and splashproof wireless data acquisition terminal through the pressure-resistant shielded cable in the longitudinal fully enclosed flow-guiding protective steel channel; inside the wireless data acquisition terminal, the microvolt-level analog signal first passes through the signal conditioning unit composed of the gain stage and the filtering stage, so that the signal amplitude is boosted to the standard analog voltage signal in the range of zero to five volts; Step S102: Compare the standard analog voltage signal with the current highest bit reference voltage, and determine the highest bit of the binary value based on the comparison result; then compare the remaining voltage difference with the second highest bit reference voltage, and so on, to complete the comparison an equal number of times as the predetermined number of quantization bits, and output a set of parallel binary value sequences as the original digital quantization signal. Step S103: Divide the binary numerical sequence into data frames of fixed length, insert a specific code pattern for synchronization at the beginning of each frame; then modulate each bit of the data frame onto a preset digital electrical frequency band carrier using frequency keying, so that the digital electrical frequency band switches between two predetermined frequency values ​​representing binary zero and binary one, and radiates outward through the built-in antenna to form a digital electrical frequency band signal for wireless reception by the host computer measurement and control platform.

[0027] The working principle and beneficial effects of the above technical solution are as follows: This embodiment uses a longitudinally fully enclosed flow-guiding protective steel channel, a pressure-resistant shielded cable, and a shock-resistant and splash-proof wireless data acquisition terminal to form an overall transmission path. This allows for the lossless transmission of the microvolt-level analog signal output by the resistance strain gauge or thin-film shear force sensor deployed in the recessed area at the root of the maze card teeth and the blind area at the junction of the reinforcing plate, in a manner resistant to electromagnetic interference, mechanical vibration, and water vapor erosion. Inside the wireless data acquisition terminal, a signal conditioning unit composed of a gain stage and a filtering stage is used to reduce the microvolt-level analog signal to a standard analog voltage signal of zero to five volts. Noise and linearity are improved; subsequently, a successive approximation analog-to-digital conversion mechanism is adopted to compare the standard analog voltage signal with a reference voltage sequence that decreases stepwise from the high bit to the low bit. After completing the comparison with the predetermined number of quantization bits, a parallel binary numerical sequence is output to form the original digital quantized signal. This digital quantized signal is divided into fixed-length data frames, and a synchronization code is inserted at the beginning of the frame. It is then mapped to a preset digital electrical frequency band carrier through frequency keying modulation, switching between predetermined frequency values ​​representing binary zero and one, and finally radiated by the built-in antenna for wireless reception by the host computer measurement and control platform.

[0028] In summary, this embodiment achieves high-sensitivity, high-resolution, and high-stability real-time digital monitoring of micro-stress and micro-shear force in the blind zone of complex mechanical structures, improving the environmental adaptability, signal integrity, and wireless transmission reliability of the structural health monitoring system, while reducing system wiring complexity and maintenance costs.

[0029] Example 3: Based on Example 2, the process of modulating each bit of a data frame onto a preset digital electrical frequency band carrier using frequency keying provided in this embodiment of the invention specifically includes the following steps: S1031: Each binary bit in the data frame is sequentially converted into a switching control instruction within a time window: if the current bit is binary zero, a control level for turning on the first reference oscillator is generated; if the current bit is binary one, a control level for turning on the second reference oscillator is generated; the first reference oscillator and the second reference oscillator output two different fixed frequencies respectively, and the frequency interval between the two is determined by the preset digital electrical frequency band bandwidth. S1032: The switching control command is sent to the selection control terminal of an electronic switching switch. The input terminal of the electronic switching switch is simultaneously connected to the output terminals of the first reference oscillator and the second reference oscillator. According to the instantaneous state of the control level, the switching switch selects the signal of one of the reference oscillators to the common output terminal, and sequentially outputs the first frequency segment or the second frequency segment corresponding to the bit sequence of the data frame on the time axis. The duration of each frequency segment is equal to the length of the time window corresponding to the bit. Adjacent frequency segments are spliced ​​without gaps to form a continuous carrier signal. S1033: The continuous carrier signal passes through a limiting amplification stage and a bandpass filter stage in sequence. The limiting amplification stage is used to eliminate the amplitude fluctuations generated during the switching moment, and the bandpass filter stage is used to suppress the harmonic components generated during the switching. The processed carrier signal is finally radiated outward through the built-in antenna to form a digital electrical frequency band signal for wireless reception by the host computer measurement and control platform.

[0030] The working principle and beneficial effects of the above technical solution are as follows: This embodiment configures a first reference oscillator and a second reference source for each binary bit, and uses an electronic switching switch to select the corresponding oscillator source in real time according to the bit state to achieve frequency keying; it outputs a fixed frequency band without interval within the bit time window to form a continuous carrier stream; the limiting amplification stage suppresses transient amplitude fluctuations during switching, and the bandpass filtering stage suppresses harmonics to maintain the purity of the carrier spectrum; it generates a frequency shift keying signal within a preset digital electrical frequency band, which is radiated by the built-in antenna to meet the requirements of low phase jitter, low harmonic distortion, and high frequency accuracy required for wireless reception by the host computer, ensuring reliable transmission of data frames in complex electromagnetic environments.

[0031] Example 4: Figure 4 As shown, based on Example 1, the process of automatically outputting electronic instructions to reach the optimal demolding and pull-out critical point provided by this embodiment of the invention specifically includes the following steps: S201: The pressure values ​​output by the radial compressive stress sensor inside the casing are continuously collected at fixed time intervals, and the pressure values ​​collected each time are stored in a first-in-first-out buffer sequence. When the number of pressure values ​​stored in the buffer sequence reaches the preset window length, the difference between two adjacent pressure values ​​is calculated and divided by the time interval to obtain a set of instantaneous first derivative values. The set of instantaneous first derivative values ​​are sorted from largest to smallest, and the value in the middle position after sorting is taken as the reference slope of the current window. Each instantaneous first derivative value is divided by the reference slope to obtain a normalized slope sequence. The normalized slope sequence changes from a group of values ​​greater than the first normalization threshold to a group of values ​​less than the second normalization threshold and then to negative values. The change pattern is a visual representation of the inflection point of the characteristic signal. S202: Mark the positions in the normalized slope sequence where three or more consecutive negative values ​​appear as candidate inflection point positions, and extract all instantaneous values ​​of the first derivative within a time interval from the candidate inflection point position. Calculate the difference between the maximum and minimum values ​​of all instantaneous values ​​of the first derivative as the slope change amplitude. When the slope change amplitude is greater than a preset amplitude threshold, confirm the candidate inflection point position as the characteristic signal attenuation inflection point, and record the absolute time value corresponding to the candidate inflection point. S203: The absolute time value is compared with the initial and final setting times in the underwater solidification test data stored in the calculation kernel. If the absolute time value is after the initial setting time and the difference between it and the final setting time is greater than a preset lag threshold, the calculation kernel generates an electronic instruction. The electronic instruction contains the identifier code of the optimal demolding and pulling critical point and the current timestamp. The electronic instruction is transmitted to the control input of the top tensioning device via the output port of the wireless data acquisition terminal.

[0032] The method for obtaining underwater setting test data under the same conditions involves the following steps simultaneously with the installation of the single-sided open / closed casing and the commencement of underwater concrete pouring: Preparing concrete test blocks under the same conditions: Samples are taken from the same batch of mixer trucks at the concrete pouring site, and at least three sets of cylindrical or cubic test blocks are prepared, with no fewer than three test blocks in each set. Simulating the underwater curing environment: The test blocks are placed in a specially designed permeable steel curing cage, which is then submerged in water at the same depth as the bottom of the casing using slings, with a depth deviation ≤0.5 m. Natural water circulation should be maintained around the curing cage, and the water temperature is recorded synchronously using a wireless temperature probe installed inside the casing. This ensures that the test blocks are always underwater and that the water temperature is consistent with the hydration environment of the concrete inside the casing. Periodic penetration resistance tests are conducted, starting from the moment of concrete pouring. Every 15–30 minutes, a set of test blocks is lifted from the water, and the penetration resistance value of the test blocks is measured using a penetration resistance meter. During the test, the surface of the test blocks is kept free of free water. The initial setting time and final setting time are determined. The initial setting time is the absolute time corresponding to the penetration resistance reaching 3.5 MPa or the design requirement value, denoted as . Final setting time: The absolute time corresponding to the penetration resistance reaching 28 MPa or the design requirement value, denoted as _____. Data will be stored in the kernel. , The corresponding water depth, water temperature, and concrete mix designation number are entered into the non-volatile memory of the calculation kernel; if multiple sets of tests are conducted, the arithmetic mean is taken as the final judgment criterion.

[0033] The working principle and beneficial effects of the above technical solution are as follows: After the stress change of the inner wall of the casing in this embodiment is captured in real time, the original pressure curve is first converted into a slope curve through a sliding buffer window, and then the slope is normalized with the help of the median benchmark; any tiny nonlinear mutation is amplified and visualized in the form of a sudden drop from a positive slope to a negative slope, avoiding noise interference. Next, only the region with consecutive negative slopes is retained as a candidate inflection point, and the maximum-minimum difference between the preceding and following intervals is used for secondary verification to ensure that only true stress relaxation is identified as the attenuation inflection point; other disturbances are automatically filtered out. When the timestamp of the inflection point is locked, the system immediately compares it with the solidification time database of underwater specimens under the same conditions: as long as the initial solidification has passed and there is still a safe lag before the final solidification, an electronic instruction containing a unique identifier and a timestamp is generated. Electronic commands are transmitted wirelessly to the top tensioning device, so the tensioning action can be triggered at the golden critical point where the concrete strength is just enough to demold but not too strong to break, thus avoiding structural damage caused by premature pull-out; the entire judgment process is unattended and completed in milliseconds, allowing the demolding operation to enter a repeatable and verifiable closed-loop control.

[0034] Example 5: Based on Example 4, the process of setting the preset amplitude threshold provided in this embodiment of the invention specifically includes the following steps: S2021: From the circumferential tangential strain data recorded during the pressing stage, each strain value is extracted sequentially, and the strain value is compared with the pre-stored yield limit strain value of the casing material. After traversing all strain values, if at least one strain value is greater than the yield limit strain value, the first judgment flag is set to high level; otherwise, it is set to low level. S2022: Extract the stable readings output by the earth pressure gauges at different elevations before concrete pouring from the earth pressure map of the silt layer outside the casing recorded during the load-bearing stage. Take out the stable readings in the order of storage. Starting from the second reading, calculate the difference between the current reading and the previous reading and take the absolute value of the difference. After traversing all adjacent reading pairs, find the maximum value among the absolute values. Compare the maximum value with the preset stability threshold value. If the maximum value is greater than the stability threshold value, set the second judgment flag to high level; otherwise, set it to low level. S2023: Combine the first and second decision flags into a two-bit binary value in the order of high level followed by low level; based on the binary value, select the corresponding amplitude threshold from a predefined sequence containing four amplitude thresholds: select the first amplitude threshold when the binary value is zero, select the second amplitude threshold when the binary value is zero, select the third amplitude threshold when the binary value is one, and select the fourth amplitude threshold when the binary value is one; use the selected amplitude threshold as the final output result to complete the amplitude threshold setting.

[0035] The working principle and beneficial effects of the above technical solution are as follows: In this embodiment, the amplitude threshold is set with real-time strain over-limit judgment and earth pressure stability judgment as prerequisites, ensuring that the amplitude threshold corresponds to the actual yield critical state of the casing material; the amplitude threshold corresponds to the actual stability of the silt layer before concrete pouring; the amplitude threshold is output only as one of the four discrete values ​​mapped by two binary logic bits, avoiding human or empirical fluctuations, and realizing the objectivity and programmability of the amplitude threshold setting.

[0036] Example 6: Based on Example 5, the process of extracting stable readings output by earth pressure gauges at different elevations before concrete pouring, as provided in this embodiment of the invention, specifically includes the following steps: S20221: Locate the data frame corresponding to the start time of concrete pouring from the earth pressure spectrum, and take all data frames within one complete vibration cycle before this data frame as the extraction interval; for each earth pressure gauge, arrange the pressure values ​​output within the extraction interval into a sequence according to the acquisition time; scan backward from the beginning of the sequence to find the pressure value with the most consecutive repetitions; if multiple pressure values ​​have the same number of consecutive repetitions, take the first pressure value to appear as the initial stable reading of the earth pressure gauge; S20222: Collect the preliminary stable readings output by all earth pressure gauges at the same elevation into a set; count the number of times each reading occurs, and take the reading with the most occurrences as the intermediate stable reading of the elevation; if there are multiple readings with the most occurrences, then arrange the readings from low to high and take the reading in the middle position as the intermediate stable reading of the elevation. S20223: Store the intermediate stable readings of each elevation in an output sequence in ascending order of elevation; starting from the second element of the output sequence, check whether the current element is equal to the previous element. If they are not equal, keep the current element; if they are equal, delete the current element and move the subsequent elements forward in sequence; after completing all checks on the output sequence, use the final sequence as the stable reading sequence output by the earth pressure gauge at different elevations before concrete pouring.

[0037] The working principle and beneficial effects of the above technical solution are as follows: This embodiment locks the data in the last vibration cycle before injection to eliminate transient interference caused by injection impact; it uses the highest number of consecutive repetitions as the screening rule to effectively filter out occasional jumps and acquisition noise, and obtain a highly reliable single-point reference value; it introduces a majority decision or median mechanism at the same elevation to reduce the system deviation caused by the drift of individual sensors, and realize the uniqueness and representativeness of the stable reading of the elevation; it uses adjacent folding to eliminate duplicate values ​​caused by dense sensor arrangement, so that the final sequence retains the true gradient difference in the vertical direction and avoids data redundancy, thereby improving the efficiency and accuracy of subsequent calculations and inversions.

[0038] Example 7: Based on Example 4, the process of generating an electronic instruction by the computing kernel provided in this embodiment of the invention specifically includes the following steps: S2031: Extract the radial compressive stress value, normalized slope value, and slope change amplitude value corresponding to the inflection point of the characteristic signal attenuation from the buffer location corresponding to the confirmed characteristic signal attenuation inflection point; simultaneously extract the average stable reading of earth pressure gauges at all different elevations within the same time window corresponding to the inflection point of the characteristic signal attenuation from the earth pressure map outside the casing; write the extracted radial compressive stress value, normalized slope value, slope change amplitude value, and average earth pressure value into a temporary data storage area in the preset field order to form the original instruction data block; S2032: Read the initial condensation time and final condensation time from the underwater condensation test data under the same conditions, calculate the time difference between the absolute time value of the characteristic signal attenuation inflection point and the initial condensation time; compare the time difference with the preset lower and upper limits of the allowable pull-out time window: if the time difference is greater than or equal to the lower limit and less than or equal to the upper limit, set the pull-out permission flag to the first value; if the time difference is less than the lower limit or greater than the upper limit, set the pull-out permission flag to the second value; append the pull-out permission flag to the end of the original command data block to obtain the expanded command data block; S2033: Combine the normalized slope value and slope change amplitude value at the inflection point of the characteristic signal attenuation. According to the preset feature code generation rules, take the two decimal places of the normalized slope value and the first two digits of the integer part of the slope change amplitude value to obtain a four-digit feature code. Write the four-digit feature code into the starting position of the extended instruction data block. Send the complete instruction data block containing the feature code, radial compressive stress value, normalized slope value, slope change amplitude value, average earth pressure, and pull-out permission flag bit outwards sequentially through the output port of the wireless data acquisition terminal to form an electronic instruction.

[0039] The working principle and beneficial effects of the above technical solution are as follows: This embodiment encapsulates the radial mechanical and morphological parameters at the moment of characteristic signal attenuation in one go to ensure data integrity; it introduces the real-time average value of earth pressure as a boundary condition verification to improve the accuracy of the field conditions reflected by the command; it dynamically generates the pull-out permission flag bit based on the condensation test data to ensure the legality of the pipe pulling operation time window; it uses a four-digit feature code to give the command a quickly identifiable identity to prevent mistransmission and forgery; and it uses a wireless port sequential transmission mechanism to send the complete command out in real time for the remote execution terminal to directly parse and act, avoiding manual intervention.

[0040] Example 8: Based on Example 7, the process of obtaining a four-digit feature code provided in this embodiment of the invention specifically includes the following steps: S20331: Convert the normalized slope value into a string, scan from the beginning of the string to find the position of the decimal point character; starting from the next character after the position, take out two characters in sequence as the first character pair; if there is only one character after the decimal point, add a zero character after that character to form the first character pair; if there is no character after the decimal point, directly take two zero characters as the first character pair. S20332: Convert the slope change value into a string. Starting from the beginning of the string, extract characters sequentially until a decimal point is encountered or the end of the string is reached. Use all extracted characters as the integer part string. Starting from the beginning of the integer part string, extract two characters sequentially to form the second character pair. If the length of the integer part string is one, add a zero character after the characters to form the second character pair. If the integer part string is empty, directly extract two zero characters as the second character pair. S20333: Write the first character pair and the second character pair into a buffer of length four characters in the order of first character pair then second character pair, so that the first two characters in the buffer are the first character pair and the last two characters are the second character pair; output the four characters in the buffer as a whole as a four-digit feature code.

[0041] The working principle and beneficial effects of the above technical solution are as follows: In this embodiment, regardless of how the length of the decimal or integer digits of the original value changes, a four-digit identifier with a uniform format and constant length is generated to ensure the determinism of the communication and parsing interface; forced zero padding eliminates ambiguity caused by numerical truncation, improving the uniqueness of the feature code and its resistance to misreading; the fixed buffer structure allows the four-digit feature code to be directly embedded in the header of the instruction data block, meeting the protocol requirements of the wireless transmission frame format for fixed field length.

[0042] Example 9: As Figure 5 As shown, based on Example 1, the process for acquiring and storing transient negative pulse differential pressure unloading electrical data provided in this embodiment of the invention specifically includes the following steps: S301: At the same moment that the top tensioning device receives the electronic command and begins to release downward, the output values ​​of the dual-diaphragm vibrating wire micro earth pressure gauge and the output values ​​of the circumferential strain gauge are read sequentially; and each pair of output values ​​read, along with the sequential number of the reading, is stored in a pre-allocated storage area. S302: Retrieve the earth pressure values ​​from two consecutive readings from the storage area, and calculate the decrease in the value of the latter value relative to the former value; when two consecutive decreases are greater than the decrease threshold value set in advance according to the opening width of the casing, mark the corresponding time as the negative pulse start time, and continue reading values ​​from the negative pulse start time until the maximum difference between three consecutive earth pressure values ​​is less than the stability threshold value set in advance according to the stable state after the casing expansion micro-shrinkage joint opens; extract all value pairs between the negative pulse start time and the stable time to form a transient data sequence; S303: Arrange the earth pressure and circumferential strain values ​​of each numerical pair in the transient data sequence in chronological order, and append the identification number of the current casing and the system time of the start-up of the top tensioning device to the beginning of the transient data sequence; store the entire transient data sequence with the appended identification number and system time into a storage device with power-off retention function to complete the acquisition and storage of transient negative pulse pressure difference unloading electrical data.

[0043] The working principle and beneficial effects of the above technical solution are as follows: This embodiment uses the synchronization of the top tensioning action and electronic command as the triggering benchmark to ensure that the read soil pressure and circumferential strain data correspond precisely with the negative pulse unloading event in time sequence; it uses two consecutive drops exceeding the drop threshold as the negative pulse start judgment condition and three consecutive differences below the stability threshold as the termination judgment condition, so that the interception boundary of the transient data sequence strictly matches the physical state of the entire process of casing opening-diameter expansion-stabilization; it adds the casing identification number and system start time to the front end of the transient data sequence, giving the data a unique identity and absolute time stamp, meeting the compliance requirements of subsequent traceability, verification and multi-source data fusion; it adopts a power-off retention type storage device to ensure that the transient negative pulse differential pressure unloading electrical data is not lost under power failure or abnormal working conditions.

[0044] Example 10: As Figure 6 As shown, based on Examples 1-9, the force measurement system for non-permanent casings based on mechanical sensors provided in this embodiment of the invention specifically includes the following steps: The equipment deployment module is used to obtain the core position, extrusion pressure position and cable burial position of the single-sided opening and closing casing; the corresponding equipment is placed at the core position, extrusion pressure position and cable burial position, and the wireless data acquisition terminal obtains the acquisition signal of the equipment and converts the microvolt-level analog signal of the acquisition signal into digital electrical frequency band. The strain data acquisition module is used during the driving stage when the single-sided open-closed casing is pressed into the soft stratum by the pile driver while the casing remains closed. The equipment continuously acquires the circumferential tangential strain data of the labyrinth tooth root in the spliced ​​section of the single-sided open-closed casing, as well as the earth pressure spectrum of the outer wall of the single-sided open-closed casing, using a high-frequency dynamic acquisition method. When a sharp increase in local stress is detected and it approaches the yield limit of the material, an audible, visual, and electrode value alarm signal is issued to indicate the suspension of pile driving or adjustment of the pile driving posture, providing digital mechanical evidence to verify the buckling resistance and tear resistance of the single-sided open-closed casing. The pressure monitoring module is used to collect and compare the following two types of pressure data in real time during the load-bearing stage of drilling dredging and concrete pouring: the soil pressure corresponding to the deep silt layer outside the single-sided open and closed casing, and the expansion pressure of the flow side generated by the gradual accumulation of concrete inside the single-sided open and closed casing, so as to realize the dynamic monitoring of fluid-solid balance. The signal inflection point confirmation module is used to track the radial compressive stress curve inside the single-sided open-closed casing in the later stage of concrete pouring. As the concrete undergoes a hydration, gelation, and solidification phase transition, it transforms from a fluid state to a plastic solid state. After the lateral outward expansion water pressure reaches its extreme value, physical shrinkage occurs, causing the radial compressive stress curve recorded by the equipment to exhibit a characteristic signal inflection point where the slope of the first derivative changes from steep to gentle and then decreases. After the kernel captures the characteristic signal attenuation inflection point, it automatically outputs an electronic command to reach the optimal demolding and pull-out critical point by combining the comparison data from underwater solidification tests under the same conditions. The instruction execution module is used to respond to electronic instructions, start the top tensioning device to release downwards, so that the single-sided opening and closing casing opens along the inclined groove to form a diameter expansion micro-shrinkage joint; at the same time, it records the data spectrum of the readings of the double diaphragm vibrating wire micro earth pressure gauge and the circumferential strain gauge, which shows a cliff-like step drop, and acquires and stores the transient negative pulse pressure difference unloading electrical data, which is used to ultimately verify the unloading and friction reduction effects of the single-sided opening and closing casing.

[0045] The working principle and beneficial effects of the above technical solution are as follows: This embodiment captures and manages all mechanical information of the four stages of pile driving, pouring, hardening, and demolding in a closed loop, without any manual cutting or removal of the casing. During the pile driving stage, the circumferential strain at the root of the maze-like retaining teeth is compared with the earth pressure spectrum of the outer wall in real time, exposing the risk of local yielding or tearing of the casing in advance. The construction party can immediately adjust the pile driving posture or stop the machine to avoid rework later. During the load-bearing stage, the earth pressure of the outer silt and the expansion pressure of the inner concrete are monitored synchronously to form a visualized curve of fluid-solid balance, ensuring that the concrete pouring process will not crack or neck due to lateral imbalance. During the hardening stage, the inflection point of the radial compressive stress curve is accurately locked by the algorithm, giving the best time to pull out the pile; without relying on experience or sampling blocks, it saves the waiting time for setting and solves the pile defects caused by premature pulling out. During the initial pulling stage, the top tensioning device and the inclined groove expansion structure work together to instantly open the micro-slits in the casing. The earth pressure gauge and strain gauge simultaneously record the cliff-like unloading waveform. The transient negative pulse data becomes the final physical evidence of the casing's stress relief and friction reduction effects, providing reusable mechanical boundary conditions for engineering iteration.

[0046] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of equivalents of this invention, this invention is also intended to include these modifications and variations.

Claims

1. A method for measuring the force on a non-permanent casing based on a mechanical sensor, characterized in that, Include: The core location, extrusion pressure location, and cable burial location of the single-sided opening and closing casing are obtained; corresponding equipment is placed at the core location, extrusion pressure location, and cable burial location, and the wireless data acquisition terminal acquires the acquisition signals of the equipment; During the pressing stage, the equipment continuously acquires circumferential tangential strain data at the root of the labyrinth tooth in the spliced ​​section of the single-sided opening and closing casing using a high-frequency dynamic acquisition method, as well as the earth pressure map of the outer wall of the single-sided opening and closing casing; providing digital mechanical evidence to verify the buckling resistance and tear resistance of the single-sided opening and closing casing. During the load-bearing phase, the equipment collects and compares earth pressure and lateral expansion pressure in real time. In the later stage of concrete pouring, the radial compressive stress curve inside the single-sided open and closed casing is tracked; and electronic commands are automatically output to reach the optimal demolding and pull-out critical point. Responding to electronic commands, the data spectrum of the readings of the dual-diaphragm vibrating wire micro earth pressure gauge and the circumferential strain gauge shows a precipitous drop, and the transient negative pulse pressure difference unloading electrical data is acquired and stored for the ultimate verification of the unloading and friction reduction effects of the single-sided opening and closing casing.

2. The method for measuring the force on a non-permanent casing based on a mechanical sensor as described in claim 1, characterized in that, in, The core area is the recessed area at the root of the toothed groove of the labyrinth structure of the inner slotted splicing section, and the blind area at the junction of the inner and outer sides of the 16mm thick reinforcing plate. The core area is used to install resistance strain gauges or thin-film shear force sensors, which are installed by spot welding or high-strength epoxy resin embedding. The extrusion pressure position is on the side wing surface of the reinforcing plate around the standard section of the casing. The extrusion pressure position is where a dual-diaphragm vibrating wire micro earth pressure gauge resistant to high-frequency vibration is embedded and installed along the elevation gradient to sense the total water and soil encapsulation extrusion pressure of the surrounding silt layer at different depths.

3. The method for measuring the force on a non-permanent casing based on a mechanical sensor as described in claim 1, characterized in that, The cable is buried at the edge of the reinforcing plate where angle steel is welded to form a longitudinally enclosed flow-guiding and protective steel trough that runs through the axis. The data lines of all sensors are introduced into the longitudinally enclosed flow-guiding and protective steel trough and lead upward to the water surface. The cable ends are connected to a shock-resistant and splash-proof wireless data acquisition terminal located below the support plate at the top of the single-sided open-closed casing. This terminal converts the microvolt-level analog signal into a digital electrical frequency band and transmits it to the host computer monitoring and control platform via a wireless network.

4. The method for measuring the force on a non-permanent casing based on a mechanical sensor as described in claim 1, characterized in that, The process of automatically outputting electronic commands to reach the optimal demolding and pull-out critical point includes the following steps: The pressure values ​​output by the radial compressive stress sensor inside the casing are continuously collected at fixed time intervals, and the pressure values ​​collected each time are stored in a first-in-first-out buffer sequence. Once the number of pressure values ​​stored in the cache sequence reaches the preset window length, backtracking from the end of the cache sequence, the difference between two adjacent pressure values ​​is calculated and divided by the time interval to obtain a set of instantaneous first derivative values. The set of instantaneous first derivative values ​​is sorted from largest to smallest, and the value in the middle position after sorting is taken as the reference slope of the current window. Each instantaneous first derivative value is divided by the reference slope to obtain a normalized slope sequence. The change pattern in the normalized slope sequence, where the numerical group above the first normalization threshold suddenly changes to below the second normalization threshold and then becomes negative, is a visual representation of the inflection point of the characteristic signal. The positions in the normalized slope sequence where three or more consecutive negative values ​​appear are marked as candidate inflection point positions. Then, all instantaneous values ​​of the first derivative within a time interval are extracted from the candidate inflection point positions. The difference between the maximum and minimum values ​​of all instantaneous values ​​of the first derivative is calculated as the slope change amplitude. When the slope change amplitude is greater than a preset amplitude threshold, the candidate inflection point position is confirmed as the characteristic signal attenuation inflection point, and the absolute time value corresponding to the candidate inflection point is recorded. The absolute time value is compared with the initial and final freezing time points in the underwater freezing test data under the same conditions: if the absolute time value is after the initial freezing time point and the difference between it and the final freezing time point is greater than a preset hysteresis threshold, then the calculation kernel generates an electronic instruction.

5. The method for measuring the force on a non-permanent casing based on a mechanical sensor as described in claim 4, characterized in that, The process of setting the preset amplitude threshold includes the following steps: From the circumferential tangential strain data recorded during the pressing stage, each strain value is sequentially extracted and compared with the pre-stored yield strength strain value of the casing material. After traversing all strain values, if at least one strain value is greater than the yield strength strain value, the first judgment flag is set to high level; otherwise, it is set to low level. From the earth pressure map of the silt layer outside the casing recorded during the load-bearing stage, the stable readings output by the earth pressure gauges at different elevations before concrete pouring are extracted. The stable readings are retrieved sequentially according to the storage order. Starting from the second reading, the difference between the current reading and the previous reading is calculated, and the absolute value of the difference is taken. After traversing all adjacent reading pairs, the maximum value among the absolute values ​​is found. The maximum value is compared with the preset stability threshold. If the maximum value is greater than the stability threshold, the second judgment flag is set to high level; otherwise, it is set to low level. The first and second decision flags are combined into a two-bit binary value in the order of high level followed by low level. Based on the binary value, the amplitude threshold at the corresponding position is selected from a predefined sequence containing four amplitude thresholds: the first amplitude threshold is selected when the binary value is zero, the second amplitude threshold is selected when the binary value is zero, the third amplitude threshold is selected when the binary value is one, and the fourth amplitude threshold is selected when the binary value is one. The selected amplitude threshold is used as the final output result, thus completing the setting of the amplitude threshold.

6. The method for measuring the force on a non-permanent casing based on a mechanical sensor as described in claim 5, characterized in that, The process of extracting stable readings from earth pressure gauges at different elevations before concrete pouring includes the following steps: Locate the data frame corresponding to the start of concrete pouring from the earth pressure map, and use all data frames within a complete vibration cycle preceding this data frame as the extraction interval; For each earth pressure gauge, the pressure values ​​output within the extraction interval are arranged into a sequence according to the acquisition time. Starting from the beginning of the sequence, the pressure value with the most consecutive repetitions is scanned to find the pressure value. If multiple pressure values ​​have the same number of consecutive repetitions, the pressure value that appears first is taken as the initial stable reading of the earth pressure gauge. The preliminary stable readings output by all earth pressure gauges at the same elevation are collected into a set; the number of times each reading occurs is counted, and the reading that occurs most frequently is taken as the intermediate stable reading of the elevation. If there are multiple readings that appear most frequently, then the readings are arranged from low to high and the one in the middle is taken as the middle stable reading of the elevation. The intermediate stable readings at each elevation are stored sequentially into an output sequence in ascending order of elevation. Starting from the second element of the output sequence, the current element is checked against the previous element. If they are not equal, the current element is retained; if they are equal, the current element is deleted and subsequent elements are shifted forward. After all checks are completed on the output sequence, the final sequence is used as the stable reading sequence output by the earth pressure gauges at different elevations before concrete pouring.

7. The method for measuring the force on a non-permanent casing based on a mechanical sensor as described in claim 4, characterized in that, The process by which the computational kernel generates an electronic instruction includes the following steps: From the cache location corresponding to the confirmed characteristic signal attenuation inflection point, extract the radial compressive stress value, normalized slope value, and slope change amplitude value corresponding to the characteristic signal attenuation inflection point at the moment the characteristic signal attenuation inflection point occurs; at the same time, extract the average stable reading of earth pressure gauges at all different elevations within the same time window corresponding to the characteristic signal attenuation inflection point from the earth pressure map outside the casing; write the extracted radial compressive stress value, normalized slope value, slope change amplitude value, and average earth pressure value into a temporary data storage area in a preset field order to form the original instruction data block; The starting and ending condensation times are read from the underwater condensation test data under the same conditions. The absolute time value of the characteristic signal attenuation inflection point and the time difference between the starting condensation time are calculated. The time difference is compared with the preset lower and upper limits of the allowable takeoff time window: if the time difference is greater than or equal to the lower limit and less than or equal to the upper limit, the takeoff permission flag is set to the first value; if the time difference is less than the lower limit or greater than the upper limit, the takeoff permission flag is set to the second value. The takeoff permission flag is appended to the end of the original command data block to obtain the expanded command data block. The normalized slope value and slope change amplitude value at the inflection point of the characteristic signal attenuation are combined. According to the preset feature code generation rules, the two decimal places of the normalized slope value are concatenated with the first two digits of the integer part of the slope change amplitude value to obtain a four-digit feature code. The four-digit feature code is written into the starting position of the extended instruction data block. The complete instruction data block, which includes the feature code, radial compressive stress value, normalized slope value, slope change amplitude value, average earth pressure, and pull-out permission flag, is sent out sequentially through the output port of the wireless data acquisition terminal to form an electronic instruction.

8. The method for measuring the force on a non-permanent casing based on a mechanical sensor as described in claim 7, characterized in that, The process of obtaining a four-digit feature code includes the following steps: Convert the normalized slope value into a string, scan from the beginning of the string to find the position of the decimal point character; starting from the next character after the position, take out two characters in sequence as the first character pair; if there is only one character after the decimal point, add a zero character after that character to form the first character pair; if there is no character after the decimal point, directly take two zero characters as the first character pair. Convert the slope change value into a string. Starting from the beginning of the string, extract characters sequentially until a decimal point is encountered or the end of the string is reached. Collect all extracted characters as the integer part string. Starting from the beginning of the integer part string, extract two characters sequentially to form the second character pair. If the length of the integer part string is one, add a zero character after the characters to form the second character pair. If the integer part string is empty, directly extract two zero characters as the second character pair. Write the first character pair and the second character pair into a buffer of length four characters in the order of first character pair then second character pair, so that the first two characters in the buffer are the first character pair and the last two characters are the second character pair; output the four characters in the buffer as a whole as a four-digit feature code.

9. The method for measuring the force on a non-permanent casing based on a mechanical sensor as described in claim 1, characterized in that, The process of acquiring and storing transient negative pulse differential pressure unloading electrical data includes the following steps: At the same moment that the top tensioning device receives the electronic command and begins to release downwards, the output values ​​of the dual-diaphragm vibrating wire micro earth pressure gauge and the output values ​​of the circumferential strain gauge are read sequentially; and each pair of output values ​​read, along with the sequential number of that read, is stored in a pre-allocated storage area. The earth pressure values ​​read from two consecutive intervals are retrieved sequentially from the storage area, and the decrease in the value of the latter interval relative to the former interval is calculated. When two consecutive decreases are greater than the decrease threshold value set in advance based on the opening width of the casing, the corresponding time is marked as the start time of the negative pulse. Values ​​are read from the start time of the negative pulse until the maximum difference between three consecutive earth pressure values ​​is less than the stability threshold value set in advance based on the stable state after the opening of the casing expansion joint. All value pairs between the start time of the negative pulse and the stable time are extracted to form a transient data sequence. The earth pressure and circumferential strain values ​​of each numerical pair in the transient data sequence are arranged in chronological order, and the identification number of the current casing and the system time of the start-up of the top tensioning device are appended to the beginning of the transient data sequence. The entire transient data sequence with the appended identification number and system time is stored in a storage device with power-off retention function to complete the acquisition and storage of transient negative pulse pressure difference unloading electrical data.

10. A force measurement system for non-permanent casing based on a mechanical sensor, used to implement the force measurement method for non-permanent casing based on a mechanical sensor as described in any one of claims 1-9, characterized in that, Include: The equipment deployment module is used to obtain the core position, extrusion pressure position and cable burial position of the single-sided opening and closing casing; the corresponding equipment is placed at the core position, extrusion pressure position and cable burial position, and the wireless data acquisition terminal obtains the acquisition signal of the equipment and converts the microvolt-level analog signal of the acquisition signal into digital electrical frequency band. The strain data acquisition module is used during the driving stage when the single-sided open-closed casing is pressed into the soft stratum by the pile driver while the casing remains closed. The equipment continuously acquires the circumferential tangential strain data of the labyrinth tooth root in the spliced ​​section of the single-sided open-closed casing and the earth pressure spectrum of the outer wall of the single-sided open-closed casing using a high-frequency dynamic acquisition method. When a sharp increase in local stress is detected and it approaches the yield limit of the material, an audible, visual and electrode value alarm signal is issued to indicate that the pile driving should be suspended or the pile driving posture should be adjusted. The pressure monitoring module is used to collect and compare the following two types of pressure data in real time during the borehole dredging and concrete pouring load-bearing stages: the soil pressure corresponding to the depth of the silt layer outside the single-sided open and closed casing, and the flow lateral expansion pressure generated by the gradual accumulation of concrete inside the single-sided open and closed casing. The signal inflection point confirmation module is used to track the radial compressive stress curve inside the single-sided open-closed casing in the later stage of concrete pouring. As the concrete undergoes a hydration, gelation, and solidification phase transition, it transforms from a fluid state to a plastic solid state. After the lateral outward expansion water pressure reaches its extreme value, physical shrinkage occurs, causing the radial compressive stress curve recorded by the equipment to exhibit a characteristic signal inflection point where the slope of the first derivative changes from steep to gentle and then decreases. After the kernel captures the characteristic signal attenuation inflection point, it automatically outputs an electronic command to reach the optimal demolding and pull-out critical point by combining the comparison data from underwater solidification tests under the same conditions. The instruction execution module is used to respond to electronic instructions, start the top tensioning device to release downwards, so that the single-sided opening and closing casing opens along the inclined groove to form a diameter expansion micro-shrinkage joint; at the same time, it records the data spectrum of the readings of the double diaphragm vibrating wire micro earth pressure gauge and the circumferential strain gauge, which shows a cliff-like step drop, and acquires and stores the transient negative pulse pressure difference unloading electrical data, which is used to ultimately verify the unloading and friction reduction effects of the single-sided opening and closing casing.

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