Cable erection construction method

Abstract

The invention provides a cable erection construction method which comprises the following steps: S1, erecting a reference cable strand located at the bottommost part, adjusting the linearity of the reference cable strand to a design requirement, and fixing the reference cable strand to form a final line shape of the reference cable strand; s2, calculating the interlayer spacing required by the adjacent layers of the upper and lower sides when the general cable strand is erected; s3, erecting a first layer of general cable strand at a specific height above the reference cable strand; s4, by taking the reference cable strand as a reference, erecting the general cable strands above the first layer of general cable strands layer by layer, and keeping the interlayer spacing calculated in the step S2 with the cable strands under the first layer of general cable strands until the rest of general cable strands are mounted; and S5, after all the cable strands are erected, cable tightening construction is conducted. By determining the interlamellar spacing between the cable strands, the interlamellar spacing prediction error of a traditional experience mode is effectively reduced, the void ratio control precision is effectively improved, the problem of local stress concentration caused by non-uniform compactness of main cable section steel wires is solved, the consistency of the main cable section compactness is ensured, and the linear correction workload after bridge forming is reduced.

Description

Technical Field

[0001] The invention relates to the field of bridge erection, in particular to a cable erection construction method. Background Art

[0002] In the field of main cable construction of suspension bridges, the main cable is the core load-bearing structure, and the precise control of its cable strand spacing directly determines the density of the main cable section, the uniformity of the gap distribution and the overall structural performance. In traditional construction methods, the determination of the layer spacing has long relied on experience, resulting in the actual void ratio deviating from the design value by more than 5%, which not only reduces the friction transmission efficiency between steel wires, but also increases the risk of internal corrosion of the main cable; on the other hand, the construction process relies on manual trial and error adjustment, and the correction of the sag of a single cable strand requires repeated measurement and positioning. The error accumulates nonlinearly with the increase in the number of cable strands, and the mid-span sag deviation often exceeds 30mm, which seriously affects the accuracy of the bridge line shape and is difficult to meet the millimeter-level construction control requirements of large-span suspension bridges. Therefore, a cable erection construction method is proposed to solve the above problems. Summary of the invention

[0003] The main purpose of the present invention is to provide a cable erection construction method to solve the problem that the determination of cable strand layer spacing has long relied on experience.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a cable erection construction method, the method comprising: S1. Install the reference cable strand at the bottom, adjust its linearity to the design requirements, and then fix it to form the final linear shape of the reference cable strand; S2. Calculate the required interlayer spacing between upper and lower adjacent layers when installing general cables; S3. Install the first layer of general cables at a specific height above the reference cables; S4, using the reference cable strand as a reference, installing the general cable strands above the first layer of general cable strands layer by layer, and maintaining the layer spacing calculated in step S2 with the cable strands directly below, until the installation of the remaining general cable strands is completed; S5. After all cables are erected, tighten the cables; The main cable is formed through the above steps.

[0005] In the preferred embodiment, the interlayer spacing shown in step S2 is quantified according to the void ratio of the cable strands, assuming that the shape of the cable strands is circular and the area of ​​the cable strands is equal: ; Where: is the number of steel wires in a single cable strand; is the wire diameter; V is the void ratio of the cable strand; is the interlayer spacing; The interlayer spacing is calculated as: ; When the calculated interlayer spacing is greater than the average value of the transverse and vertical diameters of the cable strands, the actual erection accuracy requirements are met.

[0006] In the preferred embodiment, the interlayer spacing calculation formula also includes temperature gradient correction to compensate for the effect of non-uniform thermal expansion caused by the temperature difference between the inside and outside of the cable strand on the interlayer spacing. The length change of a single steel wire due to the temperature difference is: ; Where: It is the length change of a single steel wire caused by temperature difference; is the linear expansion coefficient, ; is the length of a single steel wire; is the temperature difference between the inside and outside of the cable strand; but: ; The interlayer spacing calculation formula is: .

[0007] In the preferred solution, the interlayer spacing calculation formula also includes dynamic void ratio correction, which dynamically adjusts the interlayer spacing according to the void ratio monitored in real time to adapt to construction errors, wherein the void ratio deviation is: ; Where: The void ratio is monitored in real time; For every 1% increase in void ratio, the interlayer spacing increases by 0.5%, where 0.5% is an empirical coefficient. ; The interlayer spacing calculation formula is: .

[0008] In the preferred solution, the elevation of the general cable strand is determined according to its position in the main cable section relative to the reference cable strand, and the sag adjustment amount is calculated according to the following formula: ; Where: The size measured by calipers; is the design height difference between the adjusted cable strand and the reference cable strand; is the cable strand diameter; The upper and lower dimensions are directly measured.

[0009] In the preferred solution, when adjusting the sag of the general cable strand, the relative temperature difference between the cable strand and the reference cable strand is also included, and the calculation formula is: ; Where: is the total length change that needs to be adjusted for the cable strands; is the cable length adjustment coefficient corresponding to unit sag change; is the sag change caused by temperature difference.

[0010] In the preferred solution, S6, monitor the formed main cable, use the three-dimensional coordinate method of the total station to measure the bridge tower elevation, and measure the tower deviation change. According to the tower deviation change value and the results of the first phase of the densification point, calculate the timely coordinates of the densification point, and then use a vernier caliper to determine the top surface of the main cable, set up a special prism rod, and arrange an observation prism at the 4-point position. Then use two high-precision total stations to synchronously observe the three-dimensional coordinates of the 4-point from the upstream and downstream of the bridge for verification, and use multiple main cable linear measurements to calculate the cable clamp position.

[0011] In the preferred solution, S7, sling installation, the intersection of the sling center line and the main cable zenith line in the empty cable state is measured by the total station as the cable clamp layout reference point, and then based on the formula and Calculate the distance from the center line of the cable clamp pin to both ends, where is the horizontal inclination angle of the cable clamp, is the empty cable radius, and is the design parameter, , The distance from the intersection of the center line of the cable clamp pin shaft and the zenith line to the two ends of the cable clamp is measured along the zenith line to determine the positions of the two ends of the cable clamp, and auxiliary marking points are set 10 cm outside the extension lines of both ends. Then, the vernier caliper centering method or the total station sight line method is used to accurately lay out the zenith line and install the cable clamp. Then, the longitudinal and lateral deviations of the cable clamp are jointly remeasured, the position of the out-of-tolerance cable clamp is corrected, and the sling is installed. Finally, a string-vibration cable force meter is used to test the cable tension of the installed sling.

[0012] In the preferred solution, S8, main tower monitoring, the plane coordinates of the prism point on the top of the tower are measured by the three-dimensional coordinate method of the total station, the ground control point is used as the measuring station, and the electronic level is used to measure the elevation to the encrypted point on the top of the tower. Six rounds of measurements are carried out to record the temperature, air pressure and prism height, maintain a fixed station and orientation method, and install embedded strain sensors at the bottom of the tower, the middle tower column and the lower tower column, and a temperature sensor is installed on the top of the tower to collect data in real time and analyze the stress changes during the construction stage of the catwalk and main cable.

[0013] In the preferred solution, S9, main beam stress monitoring, surface-mounted strain sensors are installed in key sections of the steel box beam, and steel string sensors and matching data collectors are used to monitor the jacking stress in real time during construction to avoid equipment collision damage. The sensors are calibrated before installation, and the baseline data is read immediately after initial installation. Environmental parameters are recorded synchronously for each collection.

[0014] The present invention provides a cable erection construction method, which effectively reduces the error in predicting the interlayer spacing by traditional empirical methods by determining the interlayer spacing between cable strands, avoids crossing or squeezing of cable strands, reduces local stress concentration, effectively improves the accuracy of void ratio control, reduces micro-friction between cable strands, reduces the risk of fatigue fracture of steel wires, and, at the same time, reserves a fault tolerance space for construction errors, solves the problem of local stress concentration caused by uneven density of steel wires in the cross section of the main cable, ensures consistent tightness of the cross section of the main cable, and reduces the workload of linear correction after the bridge is completed. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a schematic diagram of the cable strand arrangement of the present invention; Figure 2 Schematic diagram of the cable strand spacing of the present invention; Figure 3 This is a structural diagram of the relative sag measurement of the cable strands of the present invention; Figure 4 It is a schematic diagram of the arrangement of vertical detection points of the bridge of the present invention; Figure 5 It is a schematic diagram of the measurement position of the cable clamp of the present invention; Figure 6 This is a schematic diagram of the cable clamp measurement of the present invention; Figure 7 It is a schematic diagram of bridge tower measurement of the present invention; Figure 8 It is a schematic diagram of the arrangement of the main beam elevation measurement points of the present invention; DETAILED DESCRIPTION Example 1 like Figure 1-8 As shown, a cable erection construction method, the method comprising: S1. Install the reference strand at the bottom, adjust it linearly to the design requirements, and then fix it to form the final linear shape of the reference strand. In this embodiment, each main cable contains 19 strands. First, confirm that the 1# strand is the reference strand of the main cable, and the rest are general strands. During the strand installation process, a reference strand, such as 10#, can be re-installed at an appropriate position according to construction needs to meet the needs of cable installation. The strands are arranged as shown in the following figure. Figure 1 As shown in the figure, the trigonometric height measurement method is used during the erection. When the data is processed, the correction of the local atmospheric refraction coefficient and the earth curvature is taken into account, which can greatly improve the measurement accuracy. When adjusting the cable, the cable strand needs to be moved and adjusted according to the sag adjustment ratio: cable length change / change in the horizontal elevation of the mid-span. At the same time, the span and temperature corrections are made. The basic method is to align the specific mark point of the cable strand with the corresponding mark point on the main cable saddle and fix it. Then adjust the sag of the cable strand to meet the design requirements. When the sag reaches the design requirements, fix the cable strand in the loose cable saddle, and finally adjust the anchor span tension.

[0016] The specific operation of the benchmark cable adjustment measurement is: Use the total station three-dimensional coordinate method to measure the tower top elevation change, set up stations on both sides of the bridge for opposite observation, and calculate the refraction coefficient at that time; Measuring the change of tower deflection: hang a reflective prism in the middle of the cable span, use two total stations to observe from different directions simultaneously, and conduct trigonometric height measurement; Summarize the measurement data and submit them to the monitoring and calculation team for calculation and cable adjustment instructions. After the cable adjustment is completed, measure the tower deviation and reference cable sag again; After the verticality of the reference cable strand is adjusted, stable observation is carried out for at least 3 days to confirm that the cable strand line shape fully meets the stability requirements, and the absolute elevation allowable error is (+12mm, -12mm). If all the results do not exceed the allowable deviation range, the verticality of the first cable strand is adjusted. The arithmetic average of the observation data for 3 consecutive days is used as the final line shape of the reference cable strand.

[0017] The reference cable is adjusted at night when the weather is clear, the wind speed is low, and the temperature is stable, approximately between 3:00 and 5:00 a.m. every day. When the cable is adjusted, the temperature difference between the measuring points is no more than 2°C, and the temperature difference in the cross-sectional direction of the cable is no more than 1°C. S2. Calculate the required interlayer spacing between upper and lower adjacent layers when installing general cables. When the general cable construction method of "close and distant" is adopted, the interlayer spacing between the upper and lower layers of the cable is the vertical diameter of the cable. However, in the actual installation process, it is difficult to achieve "close and distant" between the cables. The main factors are: A. Construction errors will cause gaps between the upper and lower strands; B. The cable tie makes the cable diameter larger; C. The cable strands may be bulging or loose; D. There is a temperature difference between the upper and lower strands, and the elongation of the strands is different; E. Cable strand torsion, etc.

[0018] Therefore, when erecting general cables, the cable strand interlayer spacing needs to be appropriately enlarged. The interlayer spacing is quantified according to the cable strand void ratio. Assuming that the cable strand shape is circular, the cable strand area is equal: ; Where: is the number of steel wires in a single cable strand; is the wire diameter; V is the void ratio of the cable strand; is the interlayer spacing; The interlayer spacing is calculated as: ; When the calculated interlayer spacing is greater than the average value of the transverse and vertical diameters of the cable strands, the actual erection accuracy requirements are met.

[0019] In this embodiment, the average value of the known transverse diameter and vertical diameter is 62.9 mm. Since the cable strand torsion ratio requirement is far less than 50%, if the interlayer spacing is greater than 62.9 mm, the interlayer spacing can meet the actual process erection accuracy requirement. The cable strand void ratio V% is taken as the designed main cable void ratio of 20% after cable tightening, and the interlayer spacing is calculated as:

[0020] Since the designed void ratio of the main cable is 20%, there is no increase in the difficulty of cable tightening, which ensures the feasibility of construction. At the same time, the self-weight load concentration of each cable strand will be redistributed after cable tightening. The smaller cable strand interlayer spacing makes the horizontal component and self-weight load concentration of each cable strand change less, and the impact on the cable line shape after cable tightening is also smaller.

[0021] In addition, the interlayer spacing calculation formula also includes temperature gradient correction and dynamic porosity correction. The temperature gradient correction can compensate for the influence of non-uniform thermal expansion caused by the temperature difference between the inside and outside of the cable strand on the interlayer spacing. The length change of a single steel wire due to the temperature difference is: ; Where: It is the length change of a single steel wire caused by temperature difference; is the linear expansion coefficient, ; is the length of a single steel wire; is the temperature difference between the inside and outside of the cable strand; but: ; The interlayer spacing calculation formula is: .

[0022] Dynamic void ratio correction can dynamically adjust the interlayer spacing according to the real-time monitored void ratio to adapt to construction errors, where the void ratio deviation is: ; Where: The void ratio is monitored in real time; For every 1% increase in void ratio, the interlayer spacing increases by 0.5%, where 0.5% is an empirical coefficient. ; The interlayer spacing calculation formula is: ; In this embodiment: ; ; Therefore, according to the calculation results, Δd was adjusted from 62.96mm to 63.22mm to compensate for the temperature rise and porosity deviation. The improved formula upgraded the "close and distant" method to an adaptive layer spacing control technology by coupling the temperature gradient and dynamic porosity, thus solving the limitations of the original formula in complex environments.

[0023] S3. A first layer of general cables is installed at a specific height above the reference cables, and a specific height between the general cables and the reference cables is used to prevent the general cables from contacting with the reference cables, thereby preventing the general cables from deflecting.

[0024] S4. With the reference strand as the reference, the general strands above the first layer of general strands are installed layer by layer, and the interlayer spacing calculated in step S2 is maintained with the strands directly below until the installation of the remaining general strands is completed. The specific installation method is: after the elevation of the reference strand is determined, the elevation of the general strand is determined according to its position in the main cable section with the reference strand. For the installation of the general strand, usually two methods are combined into one, that is, the marking method and the vertical adjustment method are used at the same time. When the prefabricated strand leaves the factory, a mark will be made at the center of the top of the main and loose cable saddles of the main cable. During the daytime, the cables are installed according to the marks and the strands are adjusted to be close to the theoretical position. After the temperature stabilizes at night, the elevation of the strand is accurately adjusted.

[0025] The sag adjustment is calculated according to the following formula: ; Where: The size measured by calipers; is the design height difference between the adjusted cable strand and the reference cable strand; is the cable strand diameter; The upper and lower dimensions are directly measured.

[0026] At the same time, the cable length increment should also take into account the relative temperature difference between the cable and the reference cable strand, and the calculation formula is: ; Where: is the total length change that needs to be adjusted for the cable strands; is the cable length adjustment coefficient corresponding to unit sag change; is the sag change caused by temperature difference.

[0027] S5. After all cables are installed, cable tightening construction shall be carried out.

[0028] The main cable is formed through the above steps.

[0029] After the main cable is installed, its line shape is determined. Due to the combined influence of various factors, there is a certain error between the actual line shape of the main cable and the designed line shape. In order to ensure that the line shape of the completed bridge meets the design requirements, the cable clamp design position and the length of the sling should be corrected to eliminate the construction error in the main cable installation stage. In order to ensure the accuracy of the calculation, the current structural state parameters must be measured.

[0030] S6. Monitor the formed main cable, use the total station three-dimensional coordinate method to measure the bridge tower elevation, and measure the tower deviation change. According to the tower deviation change value and the results of the first phase of densification points, calculate the timely coordinates of the densification points, and then use a vernier caliper to determine the top surface of the main cable, set up a special prism rod, and arrange observation prisms at the 4-point position. Then use two high-precision total stations to synchronously observe the 4-point three-dimensional coordinates from the upstream and downstream of the bridge for verification. Through multiple main cable linear measurements, they are used to calculate the cable clamp position.

[0031] The specific contents and conditions are as follows: While determining the cable line shape, the tower top elevation, tower top horizontal displacement, and the center position of the top surface of the loose cable saddle are measured. The observation time is arranged on a windless night. The conditions for observing the verticality of the main cable are: the temperature difference of the main cable in the length direction ΔT≤2ºC, the temperature difference in the cross-section direction ΔT≤1ºC, and the wind speed does not exceed 7.9m / s. The observation is conducted for 3 days, with 3-4 sets of data per day. According to the experience of cable strand observation, the best time for observation is 00:00~4:00 in the morning every day.

[0032] Implementation of main cable linearity measurement: The tower top station can be set up at the encrypted point on the tower top or directly at the center of the saddle for measurement. Since the encrypted point adopts forced centering plate, the instrument installation error is very small. This method is preferred. At the same time, a station is set up on the shore side to check the 4 points.

[0033] The implementation process is as follows: The bridge tower elevation is measured using the total station three-dimensional coordinate method; Measure the change in tower deviation, and calculate the timely coordinates of the encrypted points based on the tower deviation change value and the results of the first phase of encrypted points; The top surface of the main cable is determined by using a vernier caliper to center it, setting up a special prism pole and using two total stations; Observe the four points simultaneously, and use the points on both sides of the strait to verify the four points on the ground; The main cable line shape is measured four times every night. After four nights of data meet the accuracy requirements, the data are provided to the monitoring and calculation group for calculating the cable clamp position.

[0034] Main cable anchor span tension: The main cable anchor span wire tension is one of the important monitoring indicators during the construction of suspension bridges. During the main cable erection stage, the cable anchor span wire tension is monitored and compared with the theoretical value to obtain the adjustment amount. The anchor span cable force is adjusted after a part of the cable is constructed. After all the cables are erected, the anchor force is fine-tuned by monitoring the anchor wire tension and calculating the adjustment amount, and the cable saddle is deflected back to the theoretical design position.

[0035] The cable force during tensioning of the main cable strands is controlled by tensioning equipment, and the cable force is tested by tensioning equipment.

[0036] The main cable anchor span wire force test is divided into tensioning stage test and post-test. The tensioning stage test refers to the monitoring of the wire strands being tensioned; the wire strands that have been anchored will change due to temperature changes, and the monitoring of them is called post-test.

[0037] The main cable anchor span wire tension monitoring has the following main purposes: to ensure the accuracy of anchor tension; to provide measured parameters for error analysis and parameter identification of construction control; to calculate the stress-free length of the anchor span wire and the resultant force of the main cable anchor span tension.

[0038] Based on the purpose of cable force monitoring and its specific conditions, the tension test only tests the tensioned strands and adjacent strands. For long-term testing, 5% and no less than 5 strands will be selected in each anchor chamber for testing every 3 days. In major or special working conditions, all strands will be tested.

[0039] During the construction process, 5 strands are selected from each anchorage room as long-term monitoring strands. Combined with the long-term monitoring units, some strands can use cable force sensors. All strands will be tested when the main cable is erected, the stiffening beam is hoisted, and the bridge is completed.

[0040] According to the principle of long-term testing, the number of wire strands should be 5% of the total number and no less than 5. Here, 5 wire strands are selected in each anchor chamber for long-term testing. All wire strands will be tested when the main cable is erected, the sling is tensioned by 50%, the sling is completed, and the bridge is in construction.

[0041] In order to correctly analyze the bridge structure, it is necessary to consider the influence of various influencing factors. The suspension bridge is a bridge structure that is very sensitive to temperature. During construction, it is necessary to consider the influence of temperature on the bridge structure, especially the main cable. There is a difference in the internal and external temperature of the main cable surface, and the thicker the main cable, the greater the difference in internal and external temperature. The diameter of the main cable of this bridge is 28cm. In order to accurately determine the average temperature of the main cable section, it is necessary to know the temperature field distribution of the main cable section. This bridge will arrange temperature sensors in the sections close to the middle span and the sections in the main span to determine the internal and external temperature difference and temperature field of the main cable surface.

[0042] Temperature monitoring uses a temperature sensor with an accuracy of 0.1°C and is monitored using a wireless acquisition system.

[0043] Since the influence of temperature on structural deformation and internal force is quite significant, the influence of temperature on structure can be divided into uniform temperature influence and non-uniform temperature influence. Uniform temperature influence means that the whole structure is under the same temperature field, and non-uniform temperature means that the temperature of each part of the structure is inconsistent due to the influence of sunlight or heat conduction speed. The temperature change of uniform temperature field has little influence on the structure. Therefore, the construction control of suspension bridge is always carried out under the condition that the temperature of each part of the structure is as close as possible. The purpose of temperature field monitoring is to provide parameters for structural linear adjustment and monitoring calculation. The longitudinal temperature of the main cable and the temperature of the positive and negative surfaces of the bridge tower are tested using a temperature sensor with an accuracy of 0.1°C. The main cable temperature test sections are located at the tower and four points on the north and south banks, for a total of 7 test sections.

[0044] S7, sling installation, use the total station to measure the distance and set out the intersection of the sling center line and the main cable zenith line in the empty cable state, as the cable clamp setting out reference point, and then based on the formula and Calculate the distance from the center line of the cable clamp pin to both ends, where is the horizontal inclination angle of the cable clamp, is the empty cable radius, and is the design parameter, , The distance from the intersection of the center line of the cable clamp pin shaft and the zenith line to the two ends of the cable clamp is measured along the zenith line to determine the positions of the two ends of the cable clamp, and auxiliary marking points are set 10 cm outside the extension lines of both ends. Then, the vernier caliper centering method or the total station sight line method is used to accurately lay out the zenith line and install the cable clamp. Then, the longitudinal and lateral deviations of the cable clamp are jointly remeasured, the position of the out-of-tolerance cable clamp is corrected, and the sling is installed. Finally, a string-vibration cable force meter is used to test the cable tension of the installed sling.

[0045] The specific method is: cable clamp position measurement: cable clamp position data preparation.

[0046] The cable clamp layout reference point refers to the intersection of the center line of the sling and the center line of the top surface of the main cable in the empty cable state, that is, the intersection of the center line of the sling and the zenith line of the main cable in the empty cable state. The cable clamp detail layout data is calculated based on the horizontal inclination and the main cable diameter. The distance from the intersection of the center line of the sling and the zenith line to the two ends of the cable clamp is calculated. Figure 5 shown and , the positions of both ends of the cable clamp can be staked out; in order to facilitate installation and check the installation accuracy of the cable clamp, it is also necessary to mark 10cm at each end of the extension line of the cable clamp. One cable clamp needs to be staked out and marked 5 points, of which the cable clamp stakeout reference point can be staked out by total station distance measurement, and the other points can be staked out by reference point distance measurement.

[0047] The main cable zenith line measurement can be carried out in the following two ways: Vernier caliper measurement method: Rough Stakeout: Stake out the approximate location of the cable clamps during daylight hours using ground control points and make temporary marks on the main cable. Accurate layout: Accurate layout should be carried out at night when the temperature is stable and the wind is light. When staking out, use a vernier caliper to center the top surface of the main cable at both ends of the cable clamp. Connect the two midpoints and draw a line to determine the zenith line of the main cable.

[0048] Total Station Collimation Method Rough layout: First, make temporary marks on the main cable along the main cable curve to determine the approximate position of the cable clamp. Use the temporary marks as a reference to accurately lay out the cable clamp at night. Precise stakeout: Precise stakeout should be carried out at night when the temperature is stable and the wind is light. During stakeout, the total station is set up at the center point of the top surface of the main cable saddle, and the center point of the top surface of the main cable saddle on the same side of the opposite bank is looked back to stake out the zenith line of the main cable in the middle span; the center point of the top surface of the scattered cable saddle on the same side of the same bank is looked back to stake out the zenith line of the main cable in the side span.

[0049] The above two methods can be used in conjunction with each other and calibrated against each other. The total station sight line method has a faster layout speed, but requires the main cable to be more stable. It is preferred when conditions permit.

[0050] The steps for laying out the cable clamp installation position are as follows: On nights when the temperature is stable and the wind is light, set up the total station at the center point of the top of the main saddle, and measure and stake out the intersection of the center line of the sling and the zenith line of the main cable.

[0051] According to the calculated and Value, measure the distance along the marked zenith line, and determine the edge positions of the two ends of the cable clamp. To facilitate the installation of the cable clamp, make a reference mark 10 cm outside the edge line. Cable clamp position detection and monitoring The joint construction unit will re-measure the cable clamp position, and the cable clamp position that does not meet the requirements will be adjusted. The cable clamp position measurement accuracy estimation, the cable clamp layout accuracy is affected not only by the measurement error itself, but also by the temperature and span change measurement errors.

[0052] The longitudinal layout accuracy of the cable clamp is mainly affected by the position accuracy of the measuring station, the ranging accuracy of the instrument, the marking accuracy, etc. If ±2mm, ±2mm, and ±2mm are taken respectively, the longitudinal layout accuracy of the cable clamp is: Mlongitudinal = ±3.5mm.

[0053] The lateral layout accuracy of the cable clamp is mainly affected by the aiming accuracy, marking accuracy, etc. If ±2mm and ±2mm are taken respectively, the lateral layout accuracy of the cable clamp is: M horizontal = ±3.0mm.

[0054] Cable tension is one of the main monitoring indicators during the construction of a suspension bridge. Cable tension monitoring during the construction process is mainly to ensure that the cables of the main beam are in a safe state during the lifting process. Cable tension monitoring of the entire bridge when the bridge is completed is one of the measures to verify the status of the completed bridge.

[0055] Cable tension is one of the main monitoring indicators during the construction of suspension bridges. At present, there are two main methods for measuring the tension of parallel steel wire cables: force sensors and string-vibration cable tension meters. Force sensors have the advantages of high precision, fast test speed and little environmental interference, but the price is relatively high, and the installation and disassembly are relatively complicated. String-vibration cable tension meters have slow test speed, low precision, and great environmental interference, but they are cheap and easy to install and dismantle. Therefore, they are widely used in the construction monitoring of many suspension bridges and cable-stayed bridges. For the cable tension of suspension bridges, a string-vibration cable tension meter can be used for testing.

[0056] Cable force monitoring has the following main purposes: to prevent excessive cable force caused by unexpected situations; to provide measured parameters for error analysis and parameter identification of construction control; and to estimate the internal force state of stiffening beams and adjacent cables. Five pairs of installed slings are tested near the installation beam section; random tests are carried out on the slings far away from the installation beam section. During the cable installation condition, five pairs of cables near the installation cables are tested in turn, not necessarily at the same time. After the beam section is hoisted and the bridge is completed, the cable forces of all the slings are tested and analyzed.

[0057] S8. Main tower monitoring. The plane coordinates of the prism point on the top of the tower are measured by the three-dimensional coordinate method of the total station. The ground control point is used as the measuring station. The electronic level is used to measure the elevation to the encrypted point on the top of the tower. Six rounds of measurements are carried out to record the temperature, air pressure and prism height. The station and orientation methods are kept fixed. Embedded strain sensors are installed at the bottom of the tower, the middle tower column and the lower tower column. A temperature sensor is installed on the top of the tower to collect data in real time and analyze the stress changes during the construction stage of the catwalk and main cable.

[0058] Specifically: the bridge tower is offset. A station is established at the ground control point and the total station three-dimensional coordinate method is used for measurement. The monitoring points are arranged on the corners of the tower top by installing expansion bolts and prisms. During the first observation, the station, rear-sight point and inspection point are determined according to the upper visibility of the tower and the construction situation. Fixed monitoring procedures and methods are summarized. Monitoring under other working conditions uses the first station setting and orientation method to maintain data continuity. Six measurements are carried out, and the instrument automatically aims, measures and records the plane X and Y coordinates. During measurement, the temperature, air pressure, instrument and prism height are strictly recorded.

[0059] Accuracy estimation: The accuracy is mainly affected by the position accuracy of the measuring station, the distance measurement of the instrument, the angle measurement accuracy, etc. If ±2mm and ±2mm are taken respectively, the accuracy of tower deviation monitoring is: M=±2.8mm.

[0060] The bridge tower elevation is measured by the total station three-dimensional coordinate method. Six rounds of measurement are carried out. The instrument automatically aims and measures and records the plane X and Y coordinates. During the measurement, the temperature, air pressure, instrument and prism height are strictly recorded. The electronic level is used to measure the elevation to the encrypted control point on the tower top. In addition, the height difference between the two control points on the same cable tower is reviewed. The accuracy is estimated: the accuracy is mainly affected by the position accuracy of the measuring station, the instrument distance measurement, the angle measurement accuracy, etc. If ±2mm and ±2mm are taken respectively, the accuracy of tower deviation monitoring is: M=±2.8mm.

[0061] It should be noted that the stress of the main tower is measured by the stress sensor buried in the main tower during the installation of the catwalk and the main cable to monitor whether the stress of the main tower is normal during the installation of the catwalk and the main cable.

[0062] For testing components, the bridge tower stress test is carried out using an embedded JMZX-215A long-lasting steel bar strain gauge, and the temperature field test is carried out using a temperature sensor.

[0063] Test instruments and methods: stress monitoring elements use long-term intelligent steel string strain sensors, high-precision embedded concrete strain sensors, and matching data acquisition instruments. Computers are used to directly read the data collected by the data acquisition instruments.

[0064] Test sections and measuring points are arranged in the stress test section at the bottom of each main tower, and 6 embedded strain sensors are arranged in each tower column test section of the middle tower column and the lower tower column. In order to further understand the temperature gradient conditions of the main tower structure, a section is selected in the upper tower column as the temperature test section, and 12 strain and temperature sensors are arranged on each tower column.

[0065] S9. Main beam stress monitoring. Surface-mounted strain sensors are installed in key sections of steel box beams. Steel string sensors and matching data collectors are used to monitor jacking stress in real time during construction to avoid equipment collision damage. Sensors are calibrated before installation and baseline data is read immediately after initial installation. Environmental parameters are recorded synchronously for each collection.

[0066] Specifically: main beam elevation. According to the main beam segment division, a total of 22 main beam elevation observation sections are arranged in the steel box girder.

[0067] The cross-section of each main beam elevation observation section adopts 3-point control and 3 measuring points are arranged. In addition to being able to control the elevation of the main beam, the torsion angle of the main beam can also be controlled through the elevation difference of the symmetrical points. Three elevation observation points are set at the top of each main beam elevation observation section and marked with red paint.

[0068] A total of 66 main beam elevation observation points are arranged throughout the bridge. Temporary measurement points can be adjusted at any time if there is a conflict with construction or the line of sight is obstructed. After the main bridge is completed, permanent elevation observation points will be set up in cooperation with the construction unit.

[0069] For testing components, the main beam stress test is carried out using a surface-mounted long-term steel bar strain gauge, and the temperature field test is carried out using a temperature sensor.

[0070] Test section and measuring point arrangement: 6 stress test sections are arranged on the steel box girder in a single span, and 5 surface-mounted strain sensors are arranged on the test sections, with a total of 30 measuring points.

[0071] Testing instrument and method, the stress monitoring element adopts a long-lasting intelligent steel string strain sensor, a high-precision surface-mount strain sensor, and a matching data acquisition instrument, and uses a computer to directly read the data collected by the data acquisition instrument.

[0072] Sensor deployment: For the installation of sensors in the steel box girder section, the construction party needs to promptly notify the on-site monitoring personnel after the guide beam is in place in order to complete the sensor deployment. In addition, the on-site construction personnel are required to provide corresponding assistance and cooperation during the deployment process to avoid unnecessary delays in the construction period. It should be pointed out in particular that during the jacking process of the steel box girder, the construction personnel are expected to avoid the sensor measuring points as much as possible, because any accidental contact of the tool with the sensor will cause permanent damage to the sensor element.

[0073] When laying out, it is necessary to select sensors with reliable quality and stable performance. All stress sensors are calibrated before deployment. After each initial installation of the strain sensor, ensure that the strain sensor is in normal working condition. At the same time, take and record the initial reading immediately after the initial deployment.

[0074] The date, weather and temperature readings should be recorded at each time data is collected.

[0075] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A cable erection construction method, characterized in that: The method includes: S1. Install the reference cable strand at the bottom, adjust its linearity to the design requirements, and then fix it to form the final linear shape of the reference cable strand; S2. Calculate the required interlayer spacing between upper and lower adjacent layers when installing general cables; S3. Install the first layer of general cables at a specific height above the reference cables; S4, using the reference cable strand as a reference, installing the general cable strands above the first layer of general cable strands layer by layer, and maintaining the layer spacing calculated in step S2 with the cable strands directly below, until the installation of the remaining general cable strands is completed; S5. After all cables are erected, tighten the cables; The main cable is formed through the above steps.

2. A cable erection method according to claim 1, characterized in that: The interlayer spacing shown in step S2 is quantified based on the void fraction of the strands, assuming that the strands are circular and have equal areas: ； Where: is the number of steel wires in a single cable strand; is the wire diameter; V is the void ratio of the strand; is the interlayer spacing; The interlayer spacing is calculated as: ； When the calculated interlayer spacing is greater than the average value of the transverse and vertical diameters of the cable strands, the actual erection accuracy requirements are met.

3. A cable erection method according to claim 2, characterized in that: The interlayer spacing calculation formula also includes temperature gradient correction to compensate for the effect of non-uniform thermal expansion caused by the temperature difference between the inside and outside of the cable strands on the interlayer spacing. The length change of a single steel wire due to the temperature difference is: ； Where: It is the length change of a single steel wire caused by temperature difference; is the linear expansion coefficient, ; is the length of a single steel wire; is the temperature difference between the inside and outside of the cable strand; but: ； The interlayer spacing calculation formula is: 。 4. A cable erection method according to claim 3, characterized in that: The interlayer spacing calculation formula also includes dynamic void ratio correction, which dynamically adjusts the interlayer spacing according to the real-time monitored void ratio to adapt to construction errors. The void ratio deviation is: ； Where: The void ratio is monitored in real time; For every 1% increase in void ratio, the interlayer spacing increases by 0.5%, where 0.5% is an empirical coefficient. ； The interlayer spacing calculation formula is: 。 5. A cable erection construction method according to any one of claims 1 to 4, characterized in that: Generally, the elevation of the cable strand is determined according to its position in the main cable section relative to the reference cable strand, and its sag adjustment is calculated according to the following formula: ； Where: The size measured by calipers; is the design height difference between the adjusted cable strand and the reference cable strand; is the cable strand diameter; The upper and lower dimensions are directly measured.

6. A cable erection construction method according to claim 5, characterized in that: Generally, when adjusting the sag of a cable strand, the relative temperature difference between the cable strand and the reference cable strand is also included, and the calculation formula is: ； Where: is the total length change that needs to be adjusted for the cable strands; is the cable length adjustment coefficient corresponding to unit sag change; is the sag change caused by temperature difference.

7. A cable installation method according to claim 1, characterized in that: include: S6. Monitor the formed main cable, use the total station three-dimensional coordinate method to measure the bridge tower elevation, and measure the tower deviation change. According to the tower deviation change value and the results of the first phase of densification points, calculate the timely coordinates of the densification points, and then use a vernier caliper to determine the top surface of the main cable, set up a special prism rod, and arrange observation prisms at the 4-point position. Then use two high-precision total stations to synchronously observe the 4-point three-dimensional coordinates from the upstream and downstream of the bridge for verification. Through multiple main cable linear measurements, they are used to calculate the cable clamp position.

8. A cable erection method according to claim 7, characterized in that: include: S7, sling installation, use the total station to measure the distance and set out the intersection of the sling center line and the main cable zenith line in the empty cable state, as the cable clamp setting out reference point, and then based on the formula and Calculate the distance from the center line of the cable clamp pin to both ends, where is the horizontal inclination angle of the cable clamp, is the empty cable radius, and is the design parameter, , The distance from the intersection of the center line of the cable clamp pin shaft and the zenith line to the two ends of the cable clamp is measured along the zenith line to determine the positions of the two ends of the cable clamp, and auxiliary marking points are set 10 cm outside the extension lines of both ends. Then, the vernier caliper centering method or the total station sight line method is used to accurately lay out the zenith line and install the cable clamp. Then, the longitudinal and lateral deviations of the cable clamp are jointly remeasured, the position of the out-of-tolerance cable clamp is corrected, and the sling is installed. Finally, a string-vibration cable force meter is used to test the cable tension of the installed sling.

9. A cable erection construction method according to claim 8, characterized in that: include: S8. Main tower monitoring. The plane coordinates of the prism point on the top of the tower are measured by the three-dimensional coordinate method of the total station. The ground control point is used as the measuring station. The electronic level is used to measure the elevation to the encrypted point on the top of the tower. Six rounds of measurements are carried out to record the temperature, air pressure and prism height. The station and orientation methods are kept fixed. Embedded strain sensors are installed at the bottom of the tower, the middle tower column and the lower tower column. A temperature sensor is installed on the top of the tower to collect data in real time and analyze the stress changes during the construction stage of the catwalk and main cable.

10. A cable erection method according to claim 9, characterized in that: include: S9. Main beam stress monitoring. Surface-mounted strain sensors are installed in key sections of steel box beams. Steel string sensors and matching data collectors are used to monitor jacking stress in real time during construction to avoid equipment collision damage. Sensors are calibrated before installation and baseline data is read immediately after initial installation. Environmental parameters are recorded synchronously for each collection.

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