Foundation side form reinforcing device for rock ground conditions and monitoring method thereof

Abstract

The application provides a foundation side mold reinforcing device under rock foundation conditions and a monitoring method thereof, and relates to the technical field of building engineering. The method comprises the following steps: obtaining the uplift displacement of the chemical bolt at the second connecting plate of the base, and obtaining the base uplift displacement data; obtaining the inclination angle of the first connecting plate at the side surface of the column, and obtaining the column inclination angle data; performing spatial mapping on the cumulative deformation displacement, the base uplift displacement data and the column inclination angle data, and generating a collaborative deformation feature vector reflecting the collaborative deformation state of the triangular support structure; calculating the module length of the collaborative deformation feature vector, comparing the module length with the preset safety boundary standard, determining the stability state of the foundation side mold reinforcing device under rock foundation conditions according to the comparison result, and outputting the final stability monitoring result. The application avoids the local instability omission caused by the traditional overall average monitoring.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, and in particular to a foundation side formwork reinforcement device and its monitoring method under rock foundation conditions. Background Technology

[0002] When constructing foundations in rocky soil conditions, a triangular support structure consisting of columns, bases, and hydraulic struts is used to reinforce the side formwork of the foundation. During concrete pouring, the lateral pressure on the formwork dynamically increases with the pouring height, causing the stress state of each component of the reinforcement device to continuously change.

[0003] Existing monitoring methods typically collect the total expansion and contraction of the hydraulic strut brace or the absolute displacement of the base, treating the reinforcement device as a rigid body for overall evaluation. Under dynamic lateral pressure, the force transmission within the hydraulic strut brace is not uniformly distributed, and local stress concentrations easily occur at the junction of the large and small steel pipes, leading to abrupt changes in the deformation rate in this area. Existing methods cannot identify such nonlinear changes in local deformation rates, making it difficult to detect early signs of yielding in the brace.

[0004] Existing monitoring methods acquire brace elongation, base displacement, or column tilt in isolation, lacking the ability to couple and analyze multi-source displacement data in a spatial dimension. Under rock foundation conditions, the anchoring performance of base chemical bolts is closely related to the deformation of columns and braces. Monitoring data of a single component cannot reflect the coordinated deformation trend among nodes of the triangular support structure, and the failure of local nodes can easily lead to a chain reaction of instability in the overall structure. Summary of the Invention

[0005] This invention provides a foundation side formwork reinforcement device and its monitoring method for rock foundation conditions. It captures the local stress concentration phenomenon of hydraulic rod bracing under dynamic lateral pressure, separates the section with a sudden change in deformation rate from the overall deformation, and avoids the missed reporting of local instability caused by traditional overall average monitoring.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A first aspect is a monitoring method for foundation side formwork reinforcement devices under rock foundation conditions, the method comprising: Data from displacement sensors installed at the junction of the large and small steel pipes inside the hydraulic strut brace were collected to obtain the axial expansion and contraction displacement time series. Calculate the difference in displacement between adjacent sampling times in the axial expansion displacement time series to obtain the hourly change in the expansion and contraction of the diagonal brace; Based on the hourly change in the expansion and contraction of the diagonal brace, the point-by-point change in the expansion and contraction length along the time axis is calculated, and the expansion and contraction rate field of the diagonal brace is generated. The absolute difference in the amplitude of the change between adjacent measuring points in the velocity field is extracted. Sections that exceed the preset turning point standard are marked as stress concentration suspected sections; sections that do not exceed the preset turning point standard are marked as uniform stress sections; the values ​​are accumulated at each moment in the suspected sections to obtain the cumulative deformation displacement. The upward displacement of the chemical bolt at the second connecting plate of the base is obtained to obtain the upward displacement data of the base; the tilt angle at the first connecting plate on the side of the column is obtained to obtain the tilt angle data of the column. The cumulative deformation displacement, base uplift displacement data and column tilt angle data are spatially mapped to generate a collaborative deformation feature vector that reflects the collaborative deformation state of the triangular support structure. The modulus of the cooperative deformation feature vector is calculated, and the modulus is compared with the preset safety boundary standard. Based on the comparison results, the stability status of the foundation side formwork reinforcement device under rock foundation conditions is determined, and the final stability monitoring results are output.

[0007] Secondly, a foundation side formwork reinforcement device for rock foundation conditions includes columns, base, hydraulic rod bracing, formwork, and monitoring system; The bottom of the column is connected to one end of the base by bolts. Both the column and the base are made of cold-formed equilateral U-shaped steel. The column has a first elongated hole pre-drilled, and a first connecting plate is welded to both sides of the column; the base has a second elongated hole pre-drilled, and a second connecting plate is welded to both sides of the base. The hydraulic rod diagonal brace includes a large steel pipe and a small steel pipe. The small steel pipe is telescopically installed inside the large steel pipe. The two ends of the hydraulic rod diagonal brace are connected to the first elongated oval hole and the second elongated oval hole respectively by bolts. The column, the base and the hydraulic rod diagonal brace together form a triangular support structure without main ribs and secondary ribs. The template is connected to the column via the first connecting plate; the second connecting plate is equipped with chemical bolts, and the base is anchored to the rock foundation via the chemical bolts. The monitoring system includes a displacement sensor, a first displacement measuring device, an inclination measuring device, and a data processing unit; Displacement sensors are installed at the junction of the large and small steel pipes inside the hydraulic rod brace to collect axial expansion and contraction displacement data. The first displacement measuring device is installed on the top end face of the chemical bolt at the second connecting plate of the base, and is used to obtain the pull-out displacement data of the base; The tilt measuring device is installed on the first connecting plate on the side of the column to obtain the tilt angle data of the column; The data processing unit is communicatively connected to the displacement sensor, the first displacement measuring device, and the tilt measuring device, respectively, and is used to receive data collected by each measuring device and execute the data processing and stability determination steps.

[0008] The above-described solution of the present invention has at least the following beneficial effects: This method generates a brace expansion rate field by calculating the difference between adjacent sampling times in the axial expansion displacement time series, and extracts the absolute difference in the change amplitude of adjacent measuring points for local morphological classification. Within the suspected stress concentration segment, the cumulative deformation displacement is obtained by accumulating values ​​moment by moment. This method captures the local stress concentration phenomenon of hydraulic rod braces under dynamic lateral pressure, separating segments with abrupt changes in deformation rate from the overall deformation, thus avoiding the missed detection of local instability caused by traditional overall averaging monitoring.

[0009] By spatially mapping the cumulative deformation displacement, base pull-out displacement data, and column tilt angle data, a collaborative deformation feature vector is generated, and the modulus length is calculated for stability assessment. This method overcomes the limitations of isolated monitoring of single components, treating the triangular support structure composed of the column, base, and hydraulic rod brace as a mechanical whole for collaborative evaluation. It reflects the coupled deformation trend of each connection node under rock foundation conditions, provides early warning of the overall instability risk of the triangular support structure, and ensures the structural stability of the foundation side formwork reinforcement device during concrete pouring. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of a foundation side formwork reinforcement device for rock foundation conditions provided by an embodiment of the present invention.

[0011] Figure 2 This is a flowchart illustrating a monitoring method for a foundation side formwork reinforcement device under rock foundation conditions, provided by an embodiment of the present invention.

[0012] Reference numerals: 1. Column; 2. Base; 3. Hydraulic rod brace; 4. First elongated hole; 5. First connecting plate; 6. Template; 7. Second elongated hole; 8. Second connecting plate. Detailed Implementation

[0013] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0014] Reference Figure 1 , Figure 1 This is a schematic diagram of the structure of the foundation side formwork reinforcement device provided in this embodiment for use in rock foundation conditions.

[0015] This reinforcement device is applied to foundation construction in rocky conditions to provide support and reinforcement for the foundation side formwork. The entire device consists of three parts: a column 1, a base 2, and a hydraulic rod diagonal brace 3, forming a triangular support structure. The column 1 is installed vertically, with its bottom fixed to the rocky foundation surface via the base 2. The hydraulic rod diagonal brace 3 is inclined, with one end connected to the side of the column 1 via a hinged joint, and the other end connected to the base 2, forming a triangular mechanical closed frame. The angle between the column 1 and the hydraulic rod diagonal brace 3 is typically between 30 and 60 degrees in engineering configurations, determined by the column height, the placement of the base on the rocky foundation surface, and the designed length of the diagonal brace.

[0016] The column 1 is a steel column with a first connecting plate 5 fixedly installed on its side. The first connecting plate 5 is a steel connecting component, and its surface is attached to the side of the column 1 and fixed by welding. The hinge joint between the hydraulic rod brace 3 and the column 1 is located at the first connecting plate 5. This hinge joint is achieved by a pin connection, allowing the hydraulic rod brace 3 to rotate freely relative to the column 1 within a limited angle in the plane of the column 1. The diameter of the pin at the hinge joint is designed according to the maximum axial force transmitted by the brace, and its material is the same structural steel as the column and the brace.

[0017] The base 2 is a steel plate with its bottom surface in contact with the rock foundation surface. The length and width of the base 2 are determined based on the flatness of the rock foundation surface and the required bearing area. A second connecting plate 8 is fixedly installed on the base 2. The second connecting plate 8 has a set of four bolt holes arranged in a rectangle. Chemical bolts pass through each bolt hole and are anchored into the rock foundation. After anchoring, the chemical bolts firmly lock the base 2 to the rock foundation surface, and are the key anchoring components for the base 2 to resist pull-out forces and maintain the stability of the overall structure. In this embodiment, the chemical bolts are M20 specification, with a bolt diameter of 20 mm, an anchoring depth of not less than 150 mm, and a design pull-out bearing capacity of 50 kN for a single chemical bolt in granite bedrock.

[0018] The hydraulic strut brace 3 adopts a double-layer sleeve structure with a large steel pipe inside a small steel pipe. The inner diameter of the large steel pipe is slightly larger than the outer diameter of the small steel pipe, and the radial clearance between the two is controlled between 0.5 mm and 1 mm, ensuring both axial sliding flexibility and limiting radial loosening. In the initial state without applied lateral load, the large and small steel pipes are in an intermediate sleeve position, with approximately half the length of the small steel pipe inside the large steel pipe, reserving travel space in both the extension and retraction directions. At the interface where the large and small steel pipes intersect, a displacement sensor is fixedly installed along the axial direction of the brace.

[0019] A first displacement measuring device is installed at the top end face of the chemical bolt anchored to the second connecting plate 8 of the base 2. The first displacement measuring device uses the top spatial position of the chemical bolt when the initial anchoring is completed as the measurement zero point, and continuously monitors the vertical displacement of the top of the chemical bolt relative to the measurement zero point in a direction perpendicular to the bottom surface of the base 2.

[0020] An inclination measuring device is installed at the first connecting plate 5 on the side of the column 1. The inclination measuring device uses the initial vertical installation posture of the column 1 as the measurement reference and continuously measures the deflection angle of the column 1 relative to the reference caused by the lateral load.

[0021] The aforementioned displacement sensor, first displacement measuring device, and tilt measuring device are all connected to a data acquisition and processing terminal via shielded signal cables. This terminal has a built-in analog-to-digital conversion unit, microprocessor, storage unit, and network communication interface. It is responsible for synchronously acquiring the output data of each sensor according to a unified time reference, performing all subsequent monitoring data processing and analysis, and sending the monitoring results to the on-site monitoring display screen and construction management platform via the network.

[0022] Reference Figure 2 , Figure 2 This is a flowchart illustrating the monitoring method provided in this embodiment. The specific implementation process will be described in detail step by step below, following the execution order of the method steps.

[0023] Step 1: Collect data from displacement sensors to obtain the axial extension displacement time series. During concrete pouring, the foundation side formwork is subjected to lateral pressure generated by the newly poured concrete. This lateral pressure is transmitted through the side formwork to column 1, which in turn transmits the force to the hydraulic strut brace 3, causing the large and small steel pipes inside the brace to slide axially relative to each other. As the pouring height gradually increases, the resultant force of the lateral pressure of the newly poured concrete on the formwork dynamically increases, and the relative sliding amount between the large and small steel pipes also changes accordingly over time.

[0024] The displacement sensor is fixedly installed at the interface where the large and small steel pipes interlock, arranged along the axial direction of the diagonal brace. Its fixing bracket is clamped to the outer wall of the large steel pipe using a clamping method. The sensor's movable iron core connecting rod is connected to the end of the small steel pipe via a threaded joint. Under typical conditions of rock foundation construction, concrete pouring adopts a layered continuous pouring process, with each layer approximately 30 to 50 centimeters high and an interval of approximately 15 to 30 minutes between layers. Based on the expected rate of load change, the sampling period is set to once every five seconds. This sampling frequency corresponds to a Nyquist frequency of 0.1 Hz, which is far higher than the upper frequency band limits of the diagonal brace expansion and contraction response (below 5 Hz) and construction machinery vibration interference (above 10 Hz), thus fully capturing the dynamic response characteristics of the diagonal brace expansion and contraction.

[0025] According to the above sampling period, the displacement sensor continuously outputs electrical signals generated by the axial relative sliding between the large and small steel pipes. The displacement sensor is an LVDT-50 linear variable differential transformer type displacement sensor with a range of 0 mm to 50 mm. The excitation power supply is a 5V DC regulated power supply, and the output signal is a 0 to 5V DC voltage signal, with linearity better than ±0.2% of the full scale. After the sensor is installed, it is calibrated across its entire range using a laboratory calibration platform. During calibration, the sensor core is fixed to the precision micrometer slider on the calibration platform. The micrometer pushes the core to move 5 mm along the sensor axis in steps. At each step position, the sensor pauses and waits for the output voltage to stabilize before recording the corresponding voltage reading. Starting from the zero point, the displacement input values ​​and voltage output values ​​at all 11 calibration points are recorded sequentially. The resulting calibration correlation data are listed below in ascending order of displacement input values: Table 1. Calibration Correspondence Table

[0026] The displacement-voltage relationship of the above 11 calibration data points exhibits good linearity, with an output voltage increment of approximately 0.1 volts corresponding to each millimeter displacement increment. This calibration correspondence data is pre-loaded into the storage unit of the data acquisition and processing terminal in the form of a lookup table. Each record in the lookup table contains two fields: a voltage value field and a displacement value field. The voltage value field stores the output voltage value of each calibration point (with a minimum resolution of 0.001 volts), and the displacement value field stores the corresponding standard displacement value (with a minimum resolution of 0.01 millimeters). For any voltage value actually acquired between two calibration point voltage values, a linear interpolation method is used to calculate the corresponding displacement value: the two adjacent calibration voltage values ​​and their corresponding displacement values ​​in the lookup table are taken, and the displacement difference is allocated proportionally according to the voltage difference. The proportional allocation result is added to the displacement values ​​of the adjacent calibration points to obtain the axial displacement value corresponding to the voltage value. This axial displacement value is the relative axial displacement between the large and small steel pipes at the sampling time, in millimeters.

[0027] The axial displacement values ​​obtained at each sampling time are arranged in chronological order to form a displacement data sequence that changes over time, namely the axial expansion and contraction displacement time series.

[0028] In rock foundation construction environments, construction activities such as drilling, concrete vibrating, and heavy vehicle movement generate mechanical vibrations of varying amplitudes. These vibrations are transmitted to displacement sensors through the foundation, side formwork, and reinforcement devices, introducing high-frequency noise components into the axial expansion and contraction displacement time series. Based on monitoring and statistical analysis of vibration spectra at multiple rock foundation construction sites, the energy of construction machinery vibration interference is mainly concentrated in the frequency band above 10 Hz, while the axial expansion and contraction changes caused by concrete lateral pressure are determined by the layering rate of concrete pouring, with energy mainly concentrated in the low-frequency band below 5 Hz. The existence of at least a 5 Hz interval between these two frequency bands provides a sufficient transition band for filter design. Therefore, a low-pass filter with a cutoff frequency of 8 Hz is applied to the axial expansion and contraction displacement time series. The low-pass filter is implemented using a second-order Butterworth filter. This filter has a flat gain and ripple of no more than ±0.5 dB in the passband (0 to 8 Hz), and an attenuation of no less than 12 dB per octave in the stopband (above 12 Hz). It can completely preserve the low-frequency true signal components of the brace expansion and contraction, while effectively attenuating the high-frequency noise components of construction machinery vibration above the cutoff frequency. The displacement data sequence obtained after low-pass filtering is the denoised preprocessed axial expansion and contraction displacement time series.

[0029] Step 2: Calculate the difference in displacement between adjacent sampling times to obtain the hourly change in the expansion and contraction of the brace. From the denoised axial displacement time series, the axial displacement values ​​corresponding to each sampling moment are extracted sequentially in the positive direction of time progression, starting from the first sampling moment.

[0030] Pair every two adjacent sampling moments on the time axis into a time interval unit. The first sampling moment and the second sampling moment form the first time interval unit, the second sampling moment and the third sampling moment form the second time interval unit, and so on, until the end of the sequence. Starting from the beginning of the sequence, traverse all time interval units sequentially.

[0031] Within each time interval unit, a difference calculation is performed: the axial displacement value corresponding to the next sampling moment is taken, and the axial displacement value corresponding to the previous sampling moment is subtracted. The resulting difference represents the net expansion and contraction between the large and small steel pipes inside the hydraulic strut brace during the duration of that time interval unit. If the difference is positive, it indicates that the brace has undergone net elongation during that time interval; if the difference is negative, it indicates that the brace has undergone net shortening during that time interval. This net expansion and contraction is determined as the hourly change in expansion and contraction of the brace corresponding to that time interval unit. After calculating all time interval units sequentially, a set of hourly changes in expansion and contraction of the brace corresponding one-to-one with the time interval units is obtained. These are arranged in chronological order to form a sequence of hourly changes in expansion and contraction of the brace.

[0032] Step 3: Calculate the point-by-point variation of the expansion and contraction length along the time axis to generate the expansion and contraction rate field of the diagonal brace. From the hourly variation sequence of the brace expansion and contraction, two pieces of information are extracted for each time interval unit: the net expansion and contraction value corresponding to that time interval unit, and the duration of that time interval unit. Since this embodiment uses a fixed sampling period, the duration of each time interval unit is equal, which is equal to the set value of the sampling period, i.e., five seconds.

[0033] For each time interval unit, the net expansion and contraction within that unit is divided by the duration of that unit. The quotient is the average expansion and contraction rate within that time interval unit, expressed in millimeters per second. This average expansion and contraction rate characterizes the average rate of expansion and contraction of the bracing within the time period covered by that time interval unit.

[0034] Assign a time stamp to each average scaling rate. The time point corresponding to the midpoint of each time interval unit (i.e., the start time of that unit) plus 2.5 seconds is used as the time stamp for that average scaling rate. Each average scaling rate is then linked to its corresponding time stamp, forming a set of discrete data points. Plotting the time stamp value on the x-axis and the average scaling rate value on the y-axis yields a discrete set of rate points with time on the x-axis and scaling rate on the y-axis.

[0035] In this set of discrete rate points, the interval between adjacent rate points on the time axis is equal to the sampling period (five seconds). For each pair of adjacent rate points, linear interpolation is performed at equal time intervals along the line connecting them, based on their respective rate values ​​and time stamp values, to fill the rate transition value between the two points. The interpolation fineness is set to insert one interpolation point every second, so that the interval between adjacent data points on the time axis after interpolation is shortened to one second. After linear interpolation filling, the originally discrete rate points are connected on the time axis to form a continuous rate change curve. This curve and the time-rate plane region it covers constitute the brace expansion and contraction rate field. This rate field completely describes the continuous change of the expansion and contraction rate of the hydraulic rod brace on the time axis throughout the entire concrete pouring process.

[0036] Step 4: Extract the absolute difference in the amplitude of the change between adjacent measuring points in the velocity field, mark the suspected stress concentration segments and uniformly stressed segments, and obtain the cumulative deformation displacement. In the generated bracing expansion rate field, along the positive direction of the time axis, the expansion rate value corresponding to each measuring point (i.e., the time coordinate point after interpolation, with adjacent measuring points spaced one second apart) is extracted sequentially.

[0037] Group every two adjacent measuring points on the time axis. For each group, calculate the expansion and contraction rate of the subsequent measuring point minus the expansion and contraction rate of the preceding measuring point. The difference may be positive or negative. Take the absolute value of this difference; the result is the absolute drop in rate change between adjacent measuring points in that group, expressed in millimeters per second. This absolute drop reflects the drastic change in the expansion and contraction rate of the brace between two adjacent moments: a larger drop indicates a more drastic change in the expansion and contraction rate within that time range, suggesting a possible abrupt change in the stress state; a smaller drop indicates a more gradual change in the expansion and contraction rate, suggesting a more stable stress state.

[0038] Next, the preset turning rate threshold is obtained. This threshold is determined based on the rock mass mechanics parameters of the rock foundation, and is specifically obtained through finite element numerical simulation. The entire process of finite element simulation is explained in detail below.

[0039] The finite element simulation model was established as follows. Using a triangular support structure as the simulation object, finite element models of the column 1, the large steel pipe of the hydraulic strut brace 3, and the small steel pipe were established using three-dimensional spatial beam elements. Column 1 is made of Q235 structural steel with an elastic modulus of 206 gigapascals, a Poisson's ratio of 0.3, and a density of 7850 kg / m³. The large and small steel pipes of the brace used the same material parameters as the column. The base 2 was simulated using four-node shell elements with a thickness of 20 mm. For mesh generation, the column was divided into 50 beam elements along the axial direction, the large and small steel pipes of the brace were each divided into 30 beam elements, and the base was divided into 500 shell elements. The mesh size was refined in critical connection areas to ensure that the element feature length did not exceed 20 mm.

[0040] The boundary conditions for the finite element simulation are set as follows. A vertical elastic constraint is applied to the bottom surface of base 2: a spring element is applied vertically to each shell element node on the bottom surface of the base. The spring stiffness is equal to the quotient of the bedrock elastic modulus and the base area divided by the bedrock influence depth. For the granite bedrock involved in this embodiment, its elastic modulus is taken as 50 kPa, the base bottom area is taken as 0.5 square meters (length 1000 mm multiplied by width 500 mm), and the bedrock influence depth is taken as 2000 mm, referencing the stress influence range of the elastic half-space Boussinesq solution. The calculated equivalent vertical spring stiffness of each node is approximately 12.5 kN / mm. Simultaneously, a horizontal elastic constraint is applied to the nodes on the bottom surface of the base, with a spring stiffness of 1 / 10 of the vertical stiffness, to simulate the bedrock's resistance to horizontal sliding of the base. The chemical bolts were simulated using spring units: a three-way spring unit was applied at each bolt hole location. The vertical spring stiffness was taken as the bond pull-out stiffness of the chemical bolt, which was approximately 25 kN / mm based on the pull-out test data of M20 chemical bolts in granite. The horizontal spring stiffness was taken as half of the vertical stiffness.

[0041] The load application method in the finite element simulation is as follows. The lateral pressure of the concrete on the side formwork is distributed in a trapezoidal shape along the height of the column: the lateral pressure is taken as the maximum value at the top of the column (i.e., the current height of the concrete pouring surface), and the lateral pressure is taken as zero at the bottom of the column (top surface of the base). The intermediate points are calculated by linear interpolation. The maximum value of the lateral pressure is calculated based on the density of the concrete (taken as 2400 kg / m³) and the current pouring height. The pouring height starts from 0.5 meters and gradually increases in ten load steps at a rate of 0.5 meters each time, with the final pouring height being 5 meters. In each load step, a lateral distributed load corresponding to the height of that node is applied to each node of the column in the finite element model, and the displacement response of each node is obtained by solving the static equilibrium equation.

[0042] The post-processing method of the finite element simulation is as follows. In the solution results of each load step, the relative axial displacement value at the interface between the large and small steel pipes of the brace is extracted. This displacement value is divided by the time increment corresponding to that load step (taken as the average time required for each layer of concrete pouring, i.e., 1800 seconds) to obtain the average expansion rate of the brace corresponding to that load step. The ten expansion rate values ​​corresponding to the ten load steps are sorted from smallest to largest, and the largest rate value is taken as the upper limit of the normal variation range of the expansion rate of the brace under this rock condition. A safety margin of 20% is assigned to this upper limit value, i.e., multiplied by 1.2, and the result is the preset turning rate threshold. According to the above method, for granite-type hard rock foundations, the calculated upper limit of the rate is approximately between 0.04 and 0.12 mm / s, and the threshold after taking the safety margin is approximately between 0.05 and 0.15 mm / s; for sandstone or shale-type soft rock foundations (both the elastic modulus and bearing capacity are lower than granite), the upper limit of the rate is correspondingly increased, and the threshold is approximately 0.10 to 0.25 mm / s.

[0043] It should be noted that the preset turning rate threshold determined in this step serves the early identification function of local stress concentration in the diagonal bracing, and belongs to the judgment standard for the early warning level; the preset safety boundary standard value in step 7 described later serves the final judgment function of the overall stability of the triangular bracing structure, and belongs to the judgment standard for the alarm level. The relationship between the two is progressive and complementary: the rate threshold plays a role in the early stage of data processing, and when a sudden change in rate is detected, it immediately marks the suspected stress concentration segment and transmits the local anomaly information downstream through the cumulative deformation displacement; the modulus length comparison plays a role in the final stage of data processing, and makes a final judgment on the overall safety status of the structure by combining the deformation information in three directions. When the rate threshold detects a local anomaly but the modulus length is still less than the safety boundary, the system provides a warning message but does not trigger an alarm; only when the modulus length reaches or exceeds the safety boundary will the system trigger a formal instability risk alarm. This two-level progressive judgment mechanism enables the monitoring system to maintain sensitivity to early local anomalies and avoid missed reports, while avoiding frequent false alarms of overall instability due to local fluctuations.

[0044] After obtaining the preset turning rate threshold, the absolute difference in rate change between each group of adjacent measuring points is compared with this threshold one by one. If the absolute difference in rate change of a certain group is greater than the preset turning rate threshold, it indicates that the expansion and contraction rate between the two adjacent measuring points in that group has undergone a sudden change that exceeds the normal range. This sudden change means that the stress state inside the diagonal brace has been significantly redistributed before and after that moment, i.e., a local stress concentration phenomenon has occurred. In this case, the time segment spanned by the adjacent measuring points in that group is determined to be a stress concentration suspected segment. If the absolute difference in rate change of a certain group is less than or equal to the preset turning rate threshold, it indicates that the change in expansion and contraction rate between the adjacent measuring points in that group is within the normal fluctuation range, and the stress state of the diagonal brace is relatively stable within this time segment. In this case, the time segment spanned by the adjacent measuring points in that group is determined to be a uniform stress segment.

[0045] In actual construction, a single concrete pour may take several hours. Factors such as increased lateral pressure in densely reinforced areas and changes in lateral pressure distribution patterns at variable cross-section locations can lead to stress concentration in the bracing. Therefore, there may be zero, one, or more potentially stress-concentrated sections throughout a single pour.

[0046] For each time interval identified as a potential stress concentration segment, the hourly changes in the bracing's expansion and contraction (i.e., the net expansion and contraction of each unit produced in step two) across all time interval units covered by that interval are summed up. Specifically, starting from the first time interval unit, the net expansion and contraction of each unit is taken sequentially and summed until the last time interval unit. The sum obtained is the cumulative deformation displacement of the potential stress concentration segment, in millimeters. This cumulative deformation displacement represents the total axial expansion and contraction of the bracing during the stress concentration period, only counting the deformation contribution within the abnormal rate abrupt change zone, excluding normal deformation within the uniformly stressed zone. This parameter serves as a key quantitative indicator for measuring the severity of the stress concentration effect.

[0047] Step 5: Obtain the base upward displacement data and the column tilt angle data. A first displacement measuring device is installed at the top end face of the chemical bolt anchored to the second connecting plate 8 of the base 2, and begins operation from the moment the initial anchoring of the chemical bolt is completed. This device uses the spatial position of the top of the chemical bolt at the instant of anchoring completion as the measurement zero point. As concrete pouring proceeds, lateral pressure is transmitted to the base 2 through the column 1 and the hydraulic rod brace 3, and the base 2 bears an upward pull-out force. When the upward pull-out force exceeds the bond pull-out bearing capacity between the chemical bolt and the rock mass, the chemical bolt will undergo a slight upward pull-out displacement. The first displacement measuring device continuously measures the vertical offset of the top of the chemical bolt relative to the measurement zero point along a direction perpendicular to the bottom surface of the base 2. The time series of this vertical offset is the base pull-out displacement data, in millimeters.

[0048] An inclination measuring device installed at the first connecting plate 5 on the side of column 1 begins operation from the moment the initial vertical installation of column 1 is completed. This device uses the vertical posture of column 1 at the instant of installation completion as the measurement reference. As concrete pouring progresses, column 1 will deflect towards the formwork under lateral pressure. The inclination measuring device continuously measures the deflection angle of the column 1's axis relative to the initial vertical reference line and records the angle values ​​sequentially according to the sampling time; this time series of angle values ​​constitutes the column's tilt angle data. The inclination measuring device employs a microelectromechanical system (MEMS) tilt sensor, with an angle measurement accuracy of up to 0.001 degrees (approximately 0.000017 radians), enabling it to sensitively capture minute tilt changes of the column under lateral pressure.

[0049] Based on the sampling period (five seconds) used by the displacement sensor to acquire axial displacement signals, the base upward displacement data and the column tilt angle data are timestamped and aligned. Specifically, the sampling time sequence of the displacement sensor is used as the reference time axis, and the sampling times of the base upward displacement data and the column tilt angle data are matched with the times on the reference time axis. If a certain moment on the reference time axis has a corresponding original sampling record in both data sequences and the time deviation is less than 0.5 seconds, the original sampling value is directly used. If a certain moment on the reference time axis does not have a precisely corresponding sampling record in either of the two data sequences, the linear interpolation result of the two closest original sampling records before and after that moment is taken as the equivalent value for that moment. After timestamping and alignment, the axial extension displacement time sequence, the base upward displacement data, and the column tilt angle data share the same set of sampling time sequences, forming a synchronized data set that is completely synchronized on the time axis.

[0050] Step 6: Spatially map the cumulative deformation displacement, base pull-out displacement data, and column tilt angle data to generate a cooperative deformation feature vector. A local three-dimensional spatial coordinate system is established for the triangular support structure. The origin is set at the hinge node between the hydraulic rod brace 3 and the column 1, specifically the center point of the pin on the first connecting plate 5. The axis of the column 1 is used as the first coordinate axis. During installation, the column 1 is plumbly aligned to ensure that its axis deviates from the vertical direction by no more than 1 / 1000 of its height. In this typical configuration where the effective height of the column is 3 meters, the horizontal distance of the column top from the plumb line does not exceed three millimeters, and the corresponding column axis deviation angle does not exceed 0.001 radians. The axis of the hydraulic rod brace 3 is used as the second coordinate axis, forming an acute angle with the first coordinate axis. In typical engineering configurations, this angle is between 30 and 60 degrees. A direction perpendicular to both the first and second coordinate axes (column axis and brace axis) is used as the third coordinate axis, pointing outwards from the bottom surface of the base 2. These three coordinate axes together define a local three-dimensional spatial coordinate system based on the three main force directions of the triangular support structure.

[0051] The following two geometric properties of this coordinate system need to be explained. The angle between the column axis and the brace axis is usually not a right angle (between 30 and 60 degrees), therefore the first and second coordinate axes are not strictly orthogonal, and the coordinate system as a whole is a non-orthogonal affine coordinate system. The third coordinate axis is obtained by cross-product of the first two axes using the right-hand rule; therefore, the third coordinate axis is perpendicular to both the first and second coordinate axes. In a typical geometric configuration of a triangular bracing structure, the second coordinate axis is at an angle of elevation to the horizontal plane, and the third axis is approximately parallel to the horizontal plane. In subsequent modulus calculations, this coordinate system is considered an approximately orthogonal coordinate system, and the Euclidean modulus is used as an engineering approximation index of the overall deformation degree. This approximation introduces a modulus error of no more than 15% within the typical range of 30 to 60 degrees between the column and brace angles, which is an acceptable level of accuracy for engineering applications of structural safety monitoring.

[0052] The following explains the handling of projection errors on the third coordinate axis when the column is not strictly vertically installed. In actual engineering installations, the verticality deviation of the column is usually controlled within 1 / 1000 of the column height according to construction specifications. Taking an effective column height of three meters as an example, the horizontal distance of the top of the column from the plumb line does not exceed three millimeters, and the corresponding axis deviation angle does not exceed 0.001 radians. Under this installation accuracy, the maximum angle between the direction of the third coordinate axis (determined by the cross product of the column axis and the diagonal brace axis, rather than directly by the vertical direction) and the actual vertical upward pull direction of the chemical bolt also does not exceed the deviation angle of the column axis, i.e., 0.001 radians. Under this magnitude of angular deviation, the projection error generated by directly projecting the base upward displacement data along the direction of the third coordinate axis, compared with the upward displacement value itself, does not exceed the cosine error of the deviation angle, i.e., one ten-thousandth, which can be ignored in actual engineering.

[0053] After establishing the coordinate system, the three components of the cooperative deformation feature vector are generated sequentially.

[0054] Based on the obtained cumulative deformation displacement, this quantity characterizes the total expansion and contraction of the hydraulic strut brace 3 along its own axis. This cumulative deformation displacement is projected along the second coordinate axis. Since the cumulative deformation displacement is itself the displacement value along the axial direction of the brace, and the second coordinate axis is the axial direction of the brace, the two directions coincide completely. Therefore, the axial deformation component of the brace obtained after projection is numerically equal to the cumulative deformation displacement, with dimensions in millimeters. This component reflects the total axial deformation amplitude of the brace caused by lateral pressure and local stress concentration effects.

[0055] Based on the obtained base pull-out displacement data, which characterizes the total vertical pull-out of the chemical bolt, this base pull-out displacement data is projected along the third coordinate axis. As mentioned earlier, under the engineering installation condition that the column verticality deviation does not exceed 1 / 1000, the angle between the third coordinate axis and the vertical pull-out direction of the chemical bolt does not exceed 0.001 radians, and the projection error is negligible. Therefore, the vertical deformation component of the base obtained after projection is numerically equal to the base pull-out displacement data, with the dimension of millimeters. This component reflects the vertical displacement amplitude of the base chemical bolt anchoring system under the action of pull-out force.

[0056] Based on the column tilt angle data obtained in step five and the effective height of column 1, the column tilt angle data is converted into a horizontal offset of the top of column 1 along the first coordinate axis. Here, the effective height of the column is defined as the vertical distance from the top surface of base 2 to the top of column 1. In a typical engineering configuration of this embodiment, the effective height of the column is three meters. Under small-angle deflection conditions, the column tilt angle generally does not exceed two degrees. The horizontal offset of the top of the column relative to the bottom of the column (at the top surface of the base) along a direction perpendicular to the column axis is equal to the product of the effective height of the column and the sine of the column tilt angle. When the tilt angle is small, its sine value is very close to the angle value expressed in radians. Therefore, the lateral deformation component of the column is approximately equal to the product of the effective height of the column and the column tilt angle (after conversion to radians), with the dimension of millimeters.

[0057] The axial deformation components of the diagonal brace, the vertical deformation component of the base, and the lateral deformation component of the column are combined into an ordered three-dimensional array according to the order of the first coordinate axis component, the second coordinate axis component, and the third coordinate axis component. This three-dimensional array is the collaborative deformation feature vector reflecting the coordinated deformation state of the diagonal brace, the base, and the column in the triangular support structure. Each component in this vector corresponds to the deformation state of the three sides of the triangular support structure: the first component corresponds to the lateral deflection state of the column, the second component corresponds to the axial expansion and contraction state of the diagonal brace, and the third component corresponds to the vertical pull-out state of the base. The three components together constitute a complete description of the overall deformation state of the triangular support structure. A corresponding collaborative deformation feature vector is generated at each synchronous sampling time, thus obtaining the time series of collaborative deformation feature vectors.

[0058] Step 7: Calculate the magnitude of the cooperative deformation eigenvector, compare it with the preset safety boundary standard, determine the stability state, and output the monitoring results. For the three components of the collaborative deformation feature vector corresponding to the current sampling time—the axial deformation component of the brace, the vertical deformation component of the base, and the lateral deformation component of the column—the following processing is performed: Take the value of each component and calculate its square; add the square values ​​of the three components to obtain a sum; take the square root of this sum, and the resulting value is the modulus of the collaborative deformation feature vector, in millimeters. The physical meaning of this modulus is: in the local three-dimensional spatial coordinate system of the triangular support structure, the spatial Euclidean distance from the origin (the initial position of the hinge node before deformation) to the current comprehensive deformation state point determined by the three deformation components. A larger modulus indicates a larger comprehensive deformation amplitude of the three components and a more severe overall deformation of the triangular support structure; a smaller modulus indicates that the structure is closer to its initial undeformed state.

[0059] Next, we obtain the preset safety boundary standard value. This will be explained in detail in two parts: the first part describes the construction process of the mechanical analysis model for this standard value; the second part provides a complete example derivation of the standard value based on a set of typical engineering parameters.

[0060] The first part details the construction of the mechanical analysis model. This model employs a combination of static equilibrium analysis and section bearing capacity verification, determining the elastic limits of three types of deformations in three sub-steps, and then synthesizing them into a safety boundary standard value in the form of a vector magnitude.

[0061] The axial force of the diagonal brace and the reaction force of the base are solved by considering the lateral load on the column. Taking the triangular support structure as an isolated body, the resultant lateral pressure of the concrete acting on column 1 is horizontal, and the point of application of the resultant force is located at one-third of the effective height of the column (the centroid of the trapezoidal load distribution). According to the moment equilibrium condition, with the leading edge of the contact surface between the bottom surface of base 2 and the rock foundation as the moment center, the overturning moment generated by the resultant lateral pressure is balanced by the resisting moment of the axial force of the diagonal brace 3 about the same moment center, thus obtaining the axial force of the diagonal brace. Then, according to the force equilibrium conditions in both the horizontal and vertical directions, the vertical reaction force (compression is positive, pull-out is negative) and the horizontal reaction force borne by the bottom surface of the base are solved respectively. This static equilibrium solution method is called the nodal method in structural mechanics, and its correctness is guaranteed by the basic principles of statics; the derivation process need not be elaborated here.

[0062] Check the three types of elastic limit displacements respectively: The first type is the axial elastic limit displacement of the diagonal brace. The axial load-bearing mode of the large and small steel pipes in the diagonal brace is a series combination. Under axial force, the larger compressive deformation is concentrated in the section with the smaller cross-sectional area of ​​the small steel pipe. The axial elastic limit displacement of the diagonal brace is taken as the axial compression determined by Hooke's law when the axial force of the diagonal brace reaches the yield bearing capacity of the small steel pipe section. Specifically, this limit displacement equals the design yield axial force of the diagonal brace multiplied by the effective length of the diagonal brace, and then divided by the product of the cross-sectional area of ​​the small steel pipe and the elastic modulus of the small steel pipe material. Here, the design yield axial force equals the cross-sectional area of ​​the small steel pipe multiplied by the yield strength of the steel. When the axial force of the diagonal brace does not reach the yield bearing capacity, the axial deformation of the diagonal brace is within the elastic range, and the displacement has a linear relationship with the axial force.

[0063] The second category concerns the elastic limit displacement of chemically bonded bolts under pull-out force. The load-displacement relationship of a single chemically bonded bolt under pull-out force approximates a bilinear model: before the bond strength fails, it is in an elastic segment, where the displacement is proportional to the pull-out force, with the proportionality coefficient representing the bond pull-out stiffness; after the pull-out force exceeds the bond pull-out bearing capacity, it enters a slip segment. The elastic limit displacement of a chemically bonded bolt is taken as the displacement value corresponding to the end of the elastic segment, equal to the design pull-out bearing capacity of a single bolt divided by its bond pull-out stiffness. When the total pull-out force on the base is shared by multiple chemically bonded bolts, the overall vertical displacement of the base corresponding to the limit displacement reached by the chemically bonded bolt with the largest force is taken as the elastic limit value of the base's vertical deformation.

[0064] The third type is the lateral elastic limit displacement at the top of the column. The horizontal offset of the top of the column under lateral distributed load can be determined using the deflection formula for a cantilever beam under distributed load. For a column, when the maximum bending normal stress at the column root section (i.e., at the top surface of the base) reaches the yield strength of the steel, the corresponding horizontal offset at the top of the column is the lateral elastic limit displacement. This limit displacement is equal to the resultant lateral pressure (taking the design maximum value) multiplied by the cube of the effective height of the column, and then divided by a constant coefficient (determined by the load distribution form and boundary conditions) of the product of the column section moment of inertia and the elastic modulus of the steel.

[0065] The three elastic limit displacement values ​​are combined to form the standard value of the safety boundary. The axial elastic limit displacement of the diagonal brace is taken as the upper limit value of the axial deformation component of the diagonal brace in the cooperative vector under the safety boundary; the pull-out elastic limit displacement of the chemical bolt is taken as the upper limit value of the vertical deformation component of the base; and the lateral elastic limit displacement of the column top is taken as the upper limit value of the lateral deformation component of the column. These three upper limit values ​​are combined into a three-dimensional boundary vector in the order of the first coordinate axis component, the second coordinate axis component, and the third coordinate axis component. The modulus of this boundary vector is calculated. The three upper limit values ​​are squared respectively, summed, and the square root is taken. The resulting modulus value is the preset standard value of the safety boundary, with the dimension in millimeters. The significance of this standard value is: when the modulus of the actual cooperative deformation characteristic vector is less than this standard value, none of the three deformation components have exceeded their respective elastic limits, and the triangular support structure as a whole is in an elastically safe state; when the modulus reaches or exceeds this standard value, at least one deformation component has reached or exceeded its elastic limit, and the structure as a whole faces the risk of entering plasticity or instability.

[0066] After obtaining the modulus length and standard value, a comparison is performed. When the modulus length is less than the preset safety boundary standard value, it indicates that the total amount of coordinated deformation of the triangular support structure at the current moment has not yet reached the elastic limit of the structure, and all components and connection nodes of the structure are operating within a safe range. The foundation side formwork reinforcement device is currently in a safe and stable state. When the modulus length is greater than or equal to the preset safety boundary standard value, it indicates that the total deformation of the triangular support structure at the current moment has reached or exceeded the elastic limit capacity of the structure. If loading continues, the structure may undergo plastic deformation or even instability and failure. The foundation side formwork reinforcement device is currently in a state of instability risk.

[0067] Regardless of the assessment result, the data acquisition and processing terminal combines the assessment conclusion with the specific value of the modulus length, the timestamp of the current sampling time, and the specific values ​​of the three deformation components into a structured monitoring result record. This record includes a timestamp field, a status identifier field (values ​​are safe and stable or unstable and at risk), a modulus length value field (in millimeters), a brace axial deformation component field (in millimeters), a base vertical deformation component field (in millimeters), and a column lateral deformation component field (in millimeters). This record is the final stability monitoring result, which is output to the on-site monitoring display screen or construction management platform via a network interface, allowing construction management personnel to monitor the safety status of the reinforcement device in real time.

[0068] Step 8: Targeted reinforcement recommendations when an instability risk is identified. Once it is determined that the foundation side formwork reinforcement device is currently in a state of instability risk, the data acquisition and processing terminal further performs instability factor tracing analysis to guide the implementation of targeted reinforcement measures on site.

[0069] Calculate the contribution ratio of each of the three deformation components to the overall deformation. Take the square of the axial deformation component of the diagonal brace, divide it by the sum of the squares of the three components, and the resulting ratio is the contribution ratio of the axial expansion and contraction of the hydraulic rod diagonal brace 3 to the overall deformation of the triangular support structure. This value ranges from 0 to 1 and is dimensionless. Take the square of the vertical deformation component of the base, divide it by the sum of the squares of the three components, and the resulting ratio is the contribution ratio of the pull-out of the chemical bolts of base 2 to the overall deformation of the triangular support structure. Take the square of the lateral deformation component of the column, divide it by the sum of the squares of the three components, and the resulting ratio is the contribution ratio of the tilting deflection of column 1 to the overall deformation of the triangular support structure.

[0070] The physical basis for using the equal-weighted sum-of-squares method to determine the contribution ratio is explained below. The three deformation components—axial deformation of the brace, vertical deformation of the base, and lateral deformation of the column—are all of length in the cooperative deformation characteristic vector, with units of millimeters. They have been unified to the same dimensional system in the local spatial coordinate system. Under this dimensional unification, the contribution of each component to the vector magnitude is naturally determined by its own amplitude: the addend of a component in the sum of squares of the magnitude is equal to the square of its amplitude, and the proportion of this addend to the total sum of squares is the relative contribution of that component to the overall deformation. This calculation method does not require the introduction of any empirical weighting coefficients, because the meaning of the weighting coefficients is naturally embodied in the binding of the coordinate axes to the structural force direction when the coordinate system is established: the axial deformation of the brace naturally corresponds to the deformation in the brace's force direction, the vertical deformation of the base naturally corresponds to the deformation in the direction of the chemical bolt pull-out, and the lateral deformation of the column naturally corresponds to the deformation in the direction of the column's lateral deflection. Each component is already the most faithful measure of deformation in its own direction. For specific engineering scenarios where experience shows that the risk coefficient of a certain type of deformation (such as the possibility of brittle fracture due to the removal of chemical bolts) is higher than that represented by pure amplitude, the system allows setting an adjustable weighting factor in the data acquisition and processing terminal. The squared value of the corresponding component is multiplied by the weighting factor and then included in the sum of squares to adapt to the risk preferences of different projects.

[0071] The three contribution percentages are ranked and compared numerically, and the one with the largest value is identified. The deformation component corresponding to this largest contribution percentage is the dominant factor causing the current instability risk of the triangular bracing structure, and this deformation component is determined as the current dominant instability factor of the triangular bracing structure. Based on the specific type of the dominant instability factor, corresponding directional reinforcement recommendations are generated.

[0072] When the dominant instability factor is determined to be the axial deformation component of the diagonal brace, it indicates that excessive axial expansion and contraction of the hydraulic rod diagonal brace 3 is the primary cause of structural instability. The corresponding physical mechanism is that axial sliding between the large and small steel pipes inside the diagonal brace occurred beyond the design expectations. Under these circumstances, the proposed directional reinforcement is as follows: Add a steel transverse restraint hoop to the middle of the hydraulic rod diagonal brace 3. This hoop is tightly installed around the outer wall of the large steel pipe, increasing the frictional resistance between the large and small steel pipes by restricting the circumferential expansion of the large steel pipe, thereby improving the overall bending stiffness of the diagonal brace; or increase the overlap length of the large and small steel pipes in the diagonal brace, by unscrewing the adjusting nut to push the small steel pipe further into the large steel pipe, thereby increasing the effective restraint section length between them.

[0073] When the dominant instability factor is determined to be the vertical deformation component of the base, it indicates that excessive upward displacement of the chemical bolts is the primary cause of structural instability. The corresponding physical mechanism is that the bond interface between the chemical bolts and the bedrock is gradually failing. Under these circumstances, the recommended directional reinforcement is as follows: Add at least two steel counterweights, each weighing no less than 200 kg, to the outer side of the base 2's bottom surface using anchor bolts to increase the base's pull-out resistance; or perform grouting reinforcement around the chemical bolts, drilling grouting holes and injecting high-strength epoxy resin grout within a 300 mm radius circular area centered on the chemical bolts to improve the bond pull-out bearing capacity between the chemical bolts and the bedrock; or increase the bearing area of ​​the base 2's bottom surface by adding an extension plate to the outer side of the base's bottom plate using bolt connections to disperse the pull-out force.

[0074] When the dominant instability factor is determined to be the lateral deformation component of the column, it indicates that excessive lateral deflection of column 1 is the primary cause of structural instability. The corresponding physical mechanism is that the flexural stiffness of the column section is insufficient to resist the current lateral load level. Under these circumstances, the recommended directional reinforcement is as follows: On the side of column 1 opposite to the formwork, add at least one auxiliary diagonal brace. One end of this auxiliary diagonal brace is fixed to the middle height of the column using a temporary connecting clamp, and the other end is fixed to the rock foundation surface using a ground anchor, thereby increasing the number of support points for the column to resist lateral deflection; or, at the connection between column 1 and base 2, add four triangular stiffening ribs. The two right-angled sides of each rib are welded to the outer wall of the column and the top surface of the base, respectively, to enhance the flexural modulus of the column root section.

[0075] The type name of the dominant instability factor and the corresponding directional reinforcement recommendation information are added as additional fields to the monitoring result record. They are output together with the timestamp, status identifier, modulus value and three component details fields, so that construction managers can immediately obtain targeted on-site emergency response guidance when they receive an instability risk alarm.

[0076] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A monitoring method for foundation side formwork reinforcement devices under rock foundation conditions, characterized in that, Includes the following steps: Data from displacement sensors installed at the junction of the large and small steel pipes inside the hydraulic rod brace (3) were collected to obtain the axial expansion and contraction displacement time series. Calculate the difference in displacement between adjacent sampling times in the axial expansion displacement time series to obtain the hourly change in the expansion and contraction of the diagonal brace; Based on the hourly change in the expansion and contraction of the diagonal brace, the point-by-point change in the expansion and contraction length along the time axis is calculated, and the expansion and contraction rate field of the diagonal brace is generated. The absolute difference in the amplitude of the change between adjacent measuring points in the velocity field is extracted. Sections that exceed the preset turning point standard are marked as stress concentration suspected sections; sections that do not exceed the preset turning point standard are marked as uniform stress sections; the values ​​are accumulated at each moment in the suspected sections to obtain the cumulative deformation displacement. Obtain the upward displacement of the chemical bolt at the second connecting plate (8) of the base (2) to obtain the upward displacement data of the base; obtain the tilt angle at the first connecting plate (5) on the side of the column (1) to obtain the tilt angle data of the column; The cumulative deformation displacement, base uplift displacement data and column tilt angle data are spatially mapped to generate a collaborative deformation feature vector that reflects the collaborative deformation state of the triangular support structure. The modulus of the cooperative deformation feature vector is calculated, and the modulus is compared with the preset safety boundary standard. Based on the comparison results, the stability status of the foundation side formwork reinforcement device under rock foundation conditions is determined, and the final stability monitoring results are output.

2. The monitoring method for foundation side formwork reinforcement device under rock foundation conditions according to claim 1, characterized in that, Displacement sensor data were collected at the junction of the large and small steel pipes inside the hydraulic strut brace (3) to obtain the axial expansion and contraction displacement time series, including: At the interface where the large steel pipe and the small steel pipe are interlocked inside the hydraulic rod brace (3), at least one displacement sensor is fixedly installed along the axial direction of the brace. Based on the expected rate of load change during construction of the rock foundation, a sampling period matching the rate of load change is set. The electrical signal output of the displacement sensor, generated by the axial relative sliding between the large and small steel pipes, is continuously collected according to the sampling period. Based on the calibration correspondence between the electrical signal output and the physical displacement, the electrical signal output at each sampling moment is converted into the corresponding axial displacement value; The axial displacement values ​​at each sampling time are arranged sequentially in chronological order to form an axial expansion and contraction displacement time series. Based on the frequency domain distribution range of mechanical vibration interference in the construction environment of rock foundation, the axial expansion displacement time series is subjected to low-pass filtering to filter out high-frequency noise components with frequencies higher than the upper limit of the frequency domain of mechanical vibration interference, thus obtaining the denoised axial expansion displacement time series.

3. The monitoring method for foundation side formwork reinforcement device under rock foundation conditions according to claim 2, characterized in that, Calculate the difference in displacement between adjacent sampling times in the axial expansion displacement time series to obtain the hourly change in the expansion and contraction of the brace, including: From the denoised and preprocessed axial expansion displacement time series, extract the axial displacement values ​​corresponding to all sampling times in the time progression direction. Each two adjacent sampling times form a time interval unit, and all time interval units are traversed sequentially starting from the beginning of the sequence. Within each time interval unit, the axial displacement value at the next sampling time is subtracted from the axial displacement value at the previous sampling time, and the difference is the net expansion and contraction of the diagonal brace within that time interval unit. The net expansion and contraction amount is taken as the hourly change of the diagonal brace expansion and contraction corresponding to the time interval unit. Arrange the hourly changes in the expansion and contraction of the diagonal braces corresponding to all time interval units in chronological order to obtain the sequence of hourly changes in the expansion and contraction of the diagonal braces.

4. The monitoring method for foundation side formwork reinforcement device under rock foundation conditions according to claim 3, characterized in that, Based on the hourly variation of the brace's expansion and contraction, the point-by-point variation of the expansion and contraction length along the time axis is calculated, generating the brace expansion and contraction rate field, including: Based on the hourly variation sequence of the diagonal brace expansion and contraction, obtain the net expansion and contraction amount corresponding to each time interval unit and the duration of that time interval unit. Divide the net expansion / contraction within each time interval unit by the duration of that time interval unit to obtain the average expansion / contraction rate corresponding to that time interval unit. The midpoint of each time interval unit is used as the time label of the average scaling rate. The average scaling rate is associated with the corresponding time label one by one to form a discrete rate point set with time as the horizontal axis and scaling rate as the vertical axis. Based on the time axis interval between adjacent rate points in the discrete rate point set, linear interpolation is performed between adjacent rate points to make the expansion rate continuously distributed on the time axis, thus obtaining the expansion rate field of the inclined brace.

5. The monitoring method for foundation side formwork reinforcement device under rock foundation conditions according to claim 4, characterized in that, The absolute difference in the amplitude of the change between adjacent measuring points in the rate field is extracted, and the section that exceeds the preset turning point standard is marked as a suspected stress concentration section. Sections that do not exceed the preset turning point standard are marked as uniformly stressed sections; The cumulative deformation displacement is obtained by accumulating the values ​​at each time step within the suspected segment, including: In the expansion and contraction rate field of the diagonal brace, the expansion and contraction rate value corresponding to each measuring point is extracted sequentially along the time axis. Group every two adjacent measuring points on the time axis into a group, calculate the absolute value of the difference between the expansion and contraction rate value of the latter measuring point and the expansion and contraction rate value of the former measuring point, and use it as the absolute difference in the rate change of the adjacent measuring points in that group. Obtain the preset turning rate threshold determined by the combined elastic modulus of the rock mass and the friction coefficient of the joint surface in the rocky foundation; The absolute drop in rate change of each group of adjacent measuring points is compared with the preset turning rate threshold one by one. The time intervals of adjacent measuring points where the absolute drop in rate change is greater than the preset turning rate threshold are identified as suspected stress concentration intervals. The time interval where the absolute drop of the rate change is less than or equal to the preset turning rate threshold is determined as the uniform force segment. Within the time interval covered by each suspected stress concentration segment, the hourly changes in the expansion and contraction of the diagonal bracing corresponding to all time interval units contained in that time interval are accumulated one by one, and the sum obtained is the cumulative deformation displacement of that suspected stress concentration segment.

6. The monitoring method for foundation side formwork reinforcement device under rock foundation conditions according to claim 5, characterized in that, The upward displacement of the chemical bolt at the second connecting plate (8) of the base (2) is obtained to obtain the upward displacement data of the base; Obtain the tilt angle at the first connecting plate (5) on the side of the column (1) to get the column tilt angle data, including: A first displacement measuring device is installed at the top end face of the chemical bolt anchored to the second connecting plate (8) of the base (2). The position when the chemical bolt is initially anchored is taken as the measurement zero point. The vertical offset of the top of the chemical bolt relative to the measurement zero point is continuously measured in a direction perpendicular to the bottom surface of the base (2) to obtain the pull-out displacement data of the base. An inclination measuring device is installed on the first connecting plate (5) on the side of the column (1). The posture of the column (1) when it is initially vertically installed is used as the measurement reference. The deflection angle of the column (1) relative to the measurement reference is continuously measured to obtain the column inclination angle data. Based on the sampling period used by the displacement sensor to collect axial displacement signals, the data on the pull-out displacement of the base and the tilt angle of the column are time-stamped and aligned, so that the three share the same sampling time sequence on the time axis and form a synchronous data group.

7. The monitoring method for foundation side formwork reinforcement device under rock foundation conditions according to claim 6, characterized in that, Cooperative deformation feature vectors include: Using the hinge node between the hydraulic rod brace (3) and the column (1) as the origin of the coordinate system, the axial direction of the column (1) as the first coordinate axis direction, the axial direction of the hydraulic rod brace (3) as the second coordinate axis direction, and the direction that is perpendicular to both the first and second coordinate axes and points to the outside of the bottom surface of the base (2) as the third coordinate axis direction, a local three-dimensional spatial coordinate system for the triangular support structure is established. Based on the total amount of expansion and contraction of the hydraulic rod brace (3) along its own axis direction as characterized by the cumulative deformation displacement, the cumulative deformation displacement is projected along the second coordinate axis to obtain the axial deformation component of the brace. Based on the total amount of chemical bolts pulled out vertically as represented by the base pull-out displacement data, the base pull-out displacement data is projected along the third coordinate axis to obtain the vertical deformation component of the base. Based on the column tilt angle data and the effective height of the column (1), the column tilt angle data is converted into the horizontal offset of the top of the column (1) along the first coordinate axis, and the lateral deformation component of the column is obtained. The axial deformation component of the diagonal brace, the vertical deformation component of the base, and the lateral deformation component of the column are combined into a three-dimensional vector in the order of the first coordinate axis, the second coordinate axis, and the third coordinate axis. This three-dimensional vector is the cooperative deformation characteristic vector that reflects the cooperative deformation state of the diagonal brace, the base, and the column in the triangular support structure.

8. The monitoring method for foundation side formwork reinforcement device under rock foundation conditions according to claim 7, characterized in that, The final stability monitoring results include: The square values ​​of the axial deformation component of the diagonal brace, the vertical deformation component of the base, and the lateral deformation component of the column in the cooperative deformation feature vector are calculated respectively. The three square values ​​are summed and the square root of the sum is obtained. The square root value is the modulus of the cooperative deformation feature vector. The modulus comprehensively represents the overall deformation degree of the triangular support structure. Obtain the preset safety boundary standard value determined by combining the yield strength parameters of the steel in the triangular support structure, the cross-sectional dimension parameters of each member, the allowable displacement parameters of each connection node, and the allowable bearing capacity parameters of the rock foundation; The mold length is compared with the preset safety boundary standard value; when the mold length is less than the preset safety boundary standard value, the foundation side mold reinforcement device is determined to be in a safe and stable state. When the value of the mold length is greater than or equal to the preset safety boundary standard value, it is determined that the foundation side mold reinforcement device is currently in a state of instability risk. The determination of a safe and stable state or an unstable risk state is combined with the specific value of the modulus to form a structured monitoring result record, which is then output as the final stability monitoring result.

9. The monitoring method for foundation side formwork reinforcement device under rock foundation conditions according to claim 8, characterized in that, When it is determined that the foundation side formwork reinforcement device is currently in a state of instability risk, the method further includes: Based on the ratio of the square value of the axial deformation component of the diagonal brace to the sum of the three square values, the contribution ratio of the axial expansion and contraction of the hydraulic rod diagonal brace (3) to the overall deformation of the triangular support structure is determined. Based on the ratio of the square value of the vertical deformation component of the base to the sum of the three square values, determine the contribution ratio of the pull-out of the chemical bolts of the base (2) to the overall deformation of the triangular support structure. The contribution of the tilting deflection of column (1) to the overall deformation of the triangular support structure is determined by the ratio of the square value of the lateral deformation component of the column to the sum of the three square values. The deformation component corresponding to the one with the largest contribution percentage among the three is identified as the current dominant instability factor of the triangular support structure. Based on the type of dominant instability factor, corresponding targeted reinforcement recommendations are generated.

10. A foundation side formwork reinforcement device for rock foundation conditions, characterized in that, It includes columns (1), base (2), hydraulic struts (3), formwork (6), and monitoring system; The bottom of the column (1) is connected to one end of the base (2) by bolts. Both the column (1) and the base (2) are made of cold-formed equilateral U-shaped steel. The column (1) has a first elongated hole (4) and the first connecting plate (5) is welded on both sides of the column (1); the base (2) has a second elongated hole (7) and the second connecting plate (8) is welded on both sides of the base (2). The hydraulic rod diagonal brace (3) includes a large steel pipe and a small steel pipe. The small steel pipe is telescopically installed inside the large steel pipe. The two ends of the hydraulic rod diagonal brace (3) are connected to the first elongated hole (4) and the second elongated hole (7) respectively by bolts. The column (1), the base (2) and the hydraulic rod diagonal brace (3) together form a triangular support structure without main ribs and secondary ribs. The template (6) is connected to the column (1) through the first connecting plate (5); the second connecting plate (8) is equipped with chemical bolts, and the base (2) is anchored to the rock foundation through the chemical bolts; The monitoring system includes a displacement sensor, a first displacement measuring device, an inclination measuring device, and a data processing unit; The displacement sensor is installed at the junction of the large steel pipe and the small steel pipe inside the hydraulic rod brace (3) to collect axial expansion and contraction displacement data; The first displacement measuring device is installed on the top end face of the chemical bolt at the second connecting plate (8) of the base (2) to obtain the pull-out displacement data of the base; The tilt measuring device is installed on the first connecting plate (5) on the side of the column (1) to obtain the tilt angle data of the column; The data processing unit is communicatively connected to the displacement sensor, the first displacement measuring device, and the tilt measuring device, respectively, and is used to receive data collected by each measuring device and perform the data processing and stability determination steps as described in any one of claims 1 to 9.

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