Suspension bridge main cable combined wedge-shaped isolation plate anti-sliding device installation and adjustment method

Abstract

This invention relates to a method for installing and adjusting a combined wedge-shaped anti-slip device for the main cable of a suspension bridge, belonging to the technical field of long-span suspension bridges. The process involves inspecting the wedge angle accuracy, mating surface roughness, and dimensional tolerances of the double-sided wedge plates, and inspecting the surface condition and thickness uniformity of the single-sided wedge plates. The cable strand surfaces are cleaned, and the cable strand arrangement is confirmed. First, two single-sided wedge plates are symmetrically inserted into the gaps on both sides of the target cable strand array. Then, the double-sided wedge plates are aligned with the mating surfaces of the single-sided wedge plates on both sides, and a hammering force is applied along the axial direction of the cable strands to wedge the double-sided wedge plates in. The wedge depth δ of the double-sided wedge plates and the lateral displacement Δ of the single-sided wedge plates satisfy Δ=δ·tanθ, achieving lateral clamping of the cable strands. During installation, the lateral clamping force or wedge depth is monitored in real time to ensure that the wedge depth meets Δ ≤ δ. cable +δ gap This application is easy to assemble and disassemble, can dynamically adjust the clamping force according to changes in temperature and load, accurately apply the clamping force, and does not damage the steel wire.

Description

Technical Field

[0001] This invention relates to a method for installing and adjusting a combined wedge-shaped isolation plate anti-slip device for the main cable of a suspension bridge, belonging to the technical field of long-span suspension bridges. Background Technology

[0002] The development of long-span suspension bridges places higher demands on anti-slip safety. Suspension bridges, with their advantages of strong span capacity, rational structural stress distribution, and beautiful design, are the preferred bridge type for long-span bridges. As my country's transportation infrastructure continues to expand into western mountainous areas and across rivers and seas, main span records are constantly being broken. The increase in main span directly leads to two mechanical consequences: first, the wrap angle of the main cable at the saddle at the top of the tower decreases, reducing the normal pressure of the cable strands on the saddle groove and lowering the reserve of anti-slip friction; second, the imbalance of cable forces caused by live load, wind load, and temperature gradients increases, significantly increasing the longitudinal slip driving force of the main cable at the saddle. The combination of these two factors makes the anti-slip safety of the cable saddles in ultra-long-span suspension bridges a critical technical challenge.

[0003] The main cable undergoes a bending transition from an inclined section to a horizontal section at the cable saddle at the top of the tower. Under constant load, the horizontal component of the main cable on both sides is basically balanced, and the main cable and the saddle groove are kept stable by static friction. However, under the following typical working conditions, unbalanced forces are generated on both sides of the main cable in the longitudinal direction, forming a slip driving force: (1) Asymmetric live load: When only one side of the bridge span is occupied by heavy vehicles, the cable force of the main cable on that side increases, while the other side remains unchanged, resulting in a difference in unbalanced forces in the longitudinal direction at the cable saddle. For highway-railway dual-purpose bridges, the concentrated load of trains further aggravates the amplitude and frequency of this effect. (2) Wind load: Lateral wind load causes lateral displacement of the main cable, and at the same time changes the longitudinal component of the cable force on both sides through the coupling effect of the main cable-stiffening beam system, generating additional unbalanced forces. (3) Temperature gradient: The temperature difference caused by solar radiation makes the temperature distribution of the main cable on both sides of the tower uneven, and the difference in thermal expansion and contraction leads to the redistribution of cable force, resulting in a periodic slip tendency at the cable saddle. (4) Seismic action: Seismic input causes large-scale reciprocating vibration of the main cable. Under repeated unbalanced forces, the main cable at the saddle experiences cumulative slippage, which in severe cases exceeds the friction limit and produces macroscopic displacement. In the above working conditions, live load and wind load are high-frequency cyclic actions, temperature gradient is a periodic slow-varying action, and earthquake is a low-frequency occasional strong action. The superposition of multiple factors makes the main cable at the saddle in a complex stress state of alternating micro-motion and slippage for a long time.

[0004] Uncontrolled slippage of the main cable at the saddle will trigger a series of chain reactions: ① Changes in the main cable alignment, increased tower top misalignment, and bridge deck elevation shift, affecting driving comfort and structural appearance; ② Repeated fretting wear between the main cable and the saddle groove leads to damage to the protective layer on the steel wire surface, accelerating corrosion and reducing the service life of the main cable; ③ Severe slippage shortens the effective embedment length of the main cable within the saddle groove, further reducing the anti-slip safety reserve, forming a vicious cycle of "slippage-wear-reduced load-bearing capacity-accelerated slippage"; ④ Under extreme conditions, the main cable may slip entirely out of the saddle, leading to catastrophic structural failure. In engineering practice, many large-span suspension bridges both domestically and internationally have experienced cases of excessive main cable slippage at the saddle during their operation. Some bridges have had to adopt passive remedial measures such as adding auxiliary cables, reinforcing the saddle groove, or restricting traffic loads, which not only consumes a large amount of funds but also affects the normal operational function of the bridge.

[0005] Traditional anti-slip measures for cable saddles mainly include: increasing the saddle wrap angle, adding friction pads in the saddle groove, and installing fixed diaphragms. These measures have significant limitations: increasing the wrap angle requires increasing the saddle size, increasing dead load and cost; friction pads are prone to creep and loosening under long-term loads, resulting in a degraded and non-adjustable coefficient of friction; fixed diaphragms are locked in position during manufacturing and installation, making them unable to adapt to changes in clamping force requirements caused by temperature and load variations during operation, and are difficult to disassemble and maintain. With suspension bridge spans exceeding 2000m, traditional anti-slip safety measures are no longer sufficient to meet design requirements. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for installing and adjusting a combined wedge-shaped isolation plate anti-slip device for the main cable of a suspension bridge, which is convenient to install and disassemble, can dynamically adjust the clamping force according to temperature and load changes, accurately apply the clamping force, improve the anti-slip performance, and does not damage the steel wire.

[0007] The technical solution adopted by the present invention to solve the above problems is as follows: a suspension bridge main cable combined wedge-shaped isolation plate anti-slip device, which is set in the main cable saddle between every three or four rows of cable strands, including double-sided wedge-shaped steel plates and two symmetrically arranged single-sided wedge-shaped plates. The single-sided wedge-shaped plates are symmetrically inserted into the gaps on both sides of the target cable strand row, and the double-sided wedge-shaped plates are wedgeed into the single-sided wedge-shaped plates along the axial direction of the cable strands.

[0008] One side of the single-sided wedge plate is provided with a friction layer, which is in contact with the strand. The other side of the single-sided wedge plate is a smooth surface, which cooperates with the double-sided wedge plate.

[0009] The friction layer is a thermally sprayed zinc layer with a thickness greater than 100 μm.

[0010] A design method for a combined wedge-shaped separator anti-slip device for the main cable of a suspension bridge includes the following steps: Step 1: Based on the total number of main cable strands and the length of the cable saddle area, determine the number of cable strand rows covered by each anti-skid device as m and the total number of anti-skid devices for the entire bridge as n; Step 2: Determine the wedge half angle θ of the double-sided wedge plate, the wedge half angle β of the single-sided wedge plate, the friction coefficient μ1 between the single-sided wedge plate and the cable strand contact surface, and the friction coefficient μ2 between the mating surfaces of the double-sided wedge plate and the single-sided wedge plate, and ensure that the double-sided wedge plate satisfies the self-locking condition θ≤ arctan(μ2). Step 3: Establish the wedge-shaped pressure mechanical model: The normal thrust exerted by the two sides of the double-sided wedge plate on the single-sided wedge plate is N.

[0011] The lateral pressure exerted by the single-sided wedge plate on the cable strand is P. lat ,

[0012] The ratio of lateral pressure to wedging force is the wedge pressure ratio K. w :

[0013] Wherein: F d For axial hammering force, The friction angle between the single-sided wedge plate and the cable strand is φ1. The friction angle between the double-sided wedge plate and the single-sided wedge plate is φ2; Step 4: Calculate the anti-skid bearing capacity R S With anti-slip safety factor K S ,

[0014] The total anti-slip force of the entire main cable is F anti ,

[0015] The anti-slip safety factor is K s :

[0016] Among them, F cable The total positive pressure of the main cable on the bottom of the cable saddle groove μ0 is the original friction coefficient between the cable strand and the bottom surface of the saddle groove; F slide This represents the maximum slip force of the main cable at the saddle under design conditions. [Ks] is the allowable safety factor; Step 5: Dimensional deviation compensation, strand design gap is g o Before installation, the actual value of the cable strand gap g at each device location was measured.actual Calculate the deviation Δg = g actual -g o Based on Δg, the device positions are divided into three groups, and compensation strategies are determined for each group: Group A: Δg > +3mm, increase the thickness of the single-sided wedge plate; Group B: 3mm≤Δg≤+3mm, install according to standard procedure; Group C: Δg < -3mm, reduce the thickness of the single-sided wedge plate and control the wedge depth; Step Six: Temperature Compensation, Determine the Design Reference Temperature as T design The actual installation temperature measured during construction was T. install Calculate the temperature deviation ΔT = T install - T design , The change in strand diameter caused by the temperature change ΔT is:

[0017] The corresponding formula for calculating the wedge depth is:

[0018] Where, α T L is the coefficient of thermal expansion of steel wire. saddle d is the width of n strands; d is the width of n rows of main cable strands, E c For the equivalent elastic modulus, A c Let n be the cross-sectional area of ​​the strands of the nth main cable. Step 7: Main cable porosity compensation, calculate porosity from n o Reduced to n f At that time, the corresponding wedge compensation stroke is:

[0019] Where ΔD is the change in main cable diameter caused by the change in porosity, in meters. cables The number of strands covered by each group of devices; Step 8: Determine the initial target wedging depth for the installation phase.

[0020] Where, δ design To design the theoretical wedging depth corresponding to the clamping force, k is the staged compensation coefficient for porosity compaction.

[0021] The change in the main cable diameter ΔD in step seven is calculated using the following formula:

[0022] Where D0 is the initial diameter of the main cable, n0 is the initial porosity, and nf The target porosity.

[0023] The friction coefficient μ1 between the single-sided wedge plate and the contact surface of the stranded steel wire is 0.5~0.7; the friction coefficient μ2 between the mating surfaces of the double-sided wedge plate and the single-sided wedge plate is 0.08~0.15.

[0024] The wedge angle β of the single-sided wedge plate is 0.5°~2°, and the wedge angle θ of the double-sided wedge plate is 0.5°~2°.

[0025] A method for installing and adjusting a combined wedge-shaped separator anti-slip device for the main cable of a suspension bridge, the method comprising the following steps: Step 1: Inspect the wedge angle accuracy, mating surface roughness, and dimensional tolerance of the double-sided wedge plate; inspect the surface condition and thickness uniformity of the single-sided wedge plate; clean the strand surface; and confirm the strand arrangement. Step 2: First, insert two single-sided wedge plates symmetrically into the gaps on both sides of the target cable strand, and push them in along the cable strand axis to the designed depth. Then, align the double-sided wedge plate with the mating surfaces of the single-sided wedge plates on both sides, and apply hammering force along the cable strand axis to wedge the double-sided wedge plate in. Use a light hammer with multiple blows and a gradual pressure increase method. The wedge depth δ of the double-sided wedge plate and the lateral displacement Δ of the single-sided wedge plate satisfy Δ = δ·tanθ. Step 3: Monitor the lateral clamping force or wedging depth in real time using methods such as direct measurement of wedging depth, strain monitoring, or cable strand displacement monitoring, and control the wedging depth to ensure that Δ ≤ δ. cable +δ gap , Where, δ cable δ represents the elastic compression of the cable strand. gap This is for assembly clearance;

[0026] Where d is the width of the nth row of main cable strands, E c For the equivalent elastic modulus, A c Let n be the cross-sectional area of ​​the strands of the nth main cable. Step 4: When there is a deviation between the installation temperature and the design reference temperature, adjust the compensation amount δ accordingly. comp The wedge depth can be adjusted by adding or removing hammer blows, thereby correcting the clamping force in real time; when removing the double-sided wedge plate, grease is injected between the wedge mating surfaces for extraction. Step 5: During the bridge completion acceptance, record the actual wedging depth, clamping force reading, and ambient temperature of each set of devices to form an installation file. During the operation period, inspection and compensation maintenance shall be carried out in the following stages: once a quarter for 1-2 years after bridge completion, once every 6 months to 1 year for 3-10 years after bridge completion, and once every 2-3 years after 10 years after bridge completion; after each compensation adjustment, the pressure stabilization observation shall be no less than 15 minutes and the data shall be recorded to establish a clamping force evolution file for the entire life cycle.

[0027] The double-sided wedge plate is made of steel of grade 45 or higher, and the single-sided wedge plate is made of pure zinc plate or other soft materials.

[0028] Compared with existing technologies, the advantages of this invention are as follows: A combined wedge-shaped separator anti-slip device and design method for the main cable of a suspension bridge, through the inclined pressure mechanism of the double-sided wedge plate, can obtain several to tens of times the lateral clamping force with a relatively small axial hammering force, and achieves precise application and graded control of the clamping force by controlling the wedge depth. The friction coefficient μ1 between the single-sided wedge plate and the cable strand contact surface is 0.5~0.7, ensuring the clamping effect; the friction coefficient μ2 between the double-sided wedge plate and the single-sided plate mating surface is 0.08~0.15, ensuring smooth wedge insertion and quick extraction after construction, achieving both anti-slip performance and construction convenience. The single-sided wedge plate utilizes the soft properties of zinc to adapt to the micro-undulations of the steel wire surface through plastic deformation, avoiding stress concentration and steel wire damage; at the same time, it utilizes the sacrificial anode effect of zinc to provide cathodic corrosion protection for the main cable. By repeatedly wedge in and out to adjust the clamping force, the technical problem of traditional fixed separators being unable to adapt to temperature changes and porosity evolution is solved. The porosity-temperature coupled compensation design advances anti-slip design from static section verification to full-life time-varying reliability analysis, filling the theoretical gap in the full-life anti-slip design of main cables for long-span suspension bridges. During operation, maintenance only requires periodic checks of clamping force and a small amount of additional hammering; no dismantling, replacement, or large-scale construction intervention is needed. Maintenance work does not affect the normal operation of the bridge, and maintenance costs are reduced by more than an order of magnitude compared to traditional solutions. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a suspension bridge main cable combined wedge-shaped isolation plate anti-slip device according to an embodiment of the present invention; Figure 2 This is a diagram showing the initial state of the double-sided wedge-shaped partition. Figure 3 Intermediate state diagram of inserting a double-sided wedge partition into a single-sided wedge partition; Figure 4 The final state diagram of inserting a double-sided wedge partition into a single-sided wedge partition; In the diagram: 1. Main cable saddle; 2. Double-sided wedge plate; 3. Single-sided wedge plate; 4. Cable strand. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] like Figure 1 , 2 As shown in Figures 3 and 4, in this embodiment, a combined wedge-shaped isolation plate anti-slip device for the main cable of a suspension bridge is installed between every three or four rows of cable strands 4 in the main cable saddle 1. The combined wedge-shaped isolation plate anti-slip device includes a double-sided wedge plate 2 and two symmetrically arranged single-sided wedge plates 3. The double-sided wedge plate is made of 45 steel or higher material and is heat-treated. The two sides of the double-sided wedge plate are finely machined smooth wedge surfaces with a surface roughness Ra≤1.6μm and a hardness HRC22~28. The single-sided wedge plate is made of pure zinc plate (purity ≥99.9%) or other soft materials, with a hardness of HB30~40. One side of the single-sided wedge plate is a finely machined smooth surface, which forms a mating surface with the double-sided wedge plate. The coefficient of friction μ2 between the mating surfaces of the double-sided and single-sided wedge plates is 0.08~0.15. The other side of the single-sided wedge plate forms a contact surface with the stranded steel wire. A thermally sprayed zinc layer with a thickness of more than 100μm is provided on the other side of the single-sided wedge plate to increase friction, making the coefficient of friction μ1 between the single-sided wedge plate and the stranded steel wire contact surface 0.5~0.7. The single-sided wedge plates are inserted into the gaps on both sides of the target strand, and the double-sided wedge plate is wedged between the two single-sided wedge plates along the axial direction of the strand.

[0032] The aforementioned double-sided and single-sided wedge plates perform drastically different mechanical functions. The double-sided wedge plate is the core load-bearing component for force transmission, enduring hammer loads and inclined plane compressive forces; the single-sided wedge plate is a functional component in direct contact with the stranded steel wire, responsible for transmitting lateral clamping forces while protecting the surface integrity of the stranded steel wire and providing long-term corrosion protection. This functional difference determines a fundamental difference in material performance requirements between double-sided and single-sided wedge plates, necessitating a differentiated material design strategy of "rigid-flexible pairing and strength-resistance complementarity."

[0033] The double-sided wedge plate is the core load-bearing component of the device and must meet three mechanical requirements: 1. Sufficient strength to withstand repeated hammering without plastic deformation or surface crushing; 2. Good toughness to resist brittle fracture under impact load; 3. Surface hardness must be higher than the fretting wear threshold that may occur on the mating surface, ensuring that the accuracy of the mating surface does not decrease after multiple wedge-in-out cycles. After tempering (quenching + high-temperature tempering, tempering temperature 550~600℃), the comprehensive mechanical properties of 45 steel are: tensile strength σb≥600MPa, yield strength σs≥355MPa, elongation δ5≥16%, impact toughness AKU≥39J, and hardness HRC22~28. This performance range balances strength and toughness, ensuring no permanent deformation under hammering load while possessing sufficient impact toughness reserve. The mating surface between the double-sided and single-sided wedge plates is a finely machined smooth surface (roughness Ra ≤1.6μm), requiring the material to prevent surface creep or crushing under long-term contact stress. The hardness of 45 steel after quenching and tempering (HB200-250) is much higher than that of zinc plate (HB30-40). Plastic deformation at the mating surfaces mainly occurs on the zinc plate side, while the geometric accuracy of the 45 steel side remains stable over a long period, ensuring that the pressurization performance of the device does not degrade after repeated disassembly and reassembly. 45 steel also has good machinability after quenching and tempering, allowing for precision milling or grinding to achieve the required angular accuracy (±0.5°) and surface roughness of the wedge-shaped surface.

[0034] When a single-sided wedge plate comes into direct contact with the stranded steel wire, rigid contact using hard materials like steel plates during wedging can easily cause the following damage: 1. The surface hardness of the zinc plate (HB30~40) is much lower than the coating hardness of the steel wire. Under lateral clamping force, the zinc plate undergoes plastic deformation and adapts to the microscopic irregularities on the steel wire surface, forming surface contact rather than point contact. This disperses the contact stress over a larger area, avoiding indentations and microcracks on the steel wire surface caused by localized point contact. 2. The elastic modulus of zinc (E≈80~90GPa) is approximately 40% of that of steel. Under the same load, the zinc plate undergoes greater contact deformation and a stronger wrapping effect on the steel wire surface, effectively eliminating stress concentration that may occur on hard contact surfaces. 3. During construction, slight angular deviations are unavoidable when hammering the wedge. The soft zinc plate can absorb these deviations through its own deformation without transferring the impact stress to the steel wire, thus preventing scratches or marks on the steel wire surface.

[0035] Cathodic protection of steel wire by zinc plate: The standard electrode potential of zinc (-0.76 V) is lower than that of iron (-0.44 V), and in the electrochemical sequence, zinc is the anode and steel is the cathode. When the zinc plate and steel wire come into contact in a humid environment, the zinc plate, as a sacrificial anode, preferentially corrodes, protecting the steel wire from electrochemical corrosion through the cathodic protection effect. This protection mechanism has three functions: ① Direct contact protection—the zinc plate adheres tightly to the surface of the steel wire, forming a physical barrier to isolate moisture and oxygen; ② Cathodic electrochemical protection—even if there are minor defects or coating damage on the surface of the steel wire, the zinc plate still provides electrochemical protection through the sacrificial anode effect; ③ Self-sealing effect of corrosion products—the dense basic zinc carbonate [Zn5(CO3)2(OH)6] film generated by the corrosion of the zinc plate fills the micro-gaps between the steel wire and the zinc plate, further preventing the intrusion of corrosive media.

[0036] The pairing of 45 steel (hard) and zinc (soft) concentrates contact deformation on the zinc plate side, achieving a rigid-flexible pairing and avoiding the contact stress concentration and fretting wear that may occur with a hard-hard pairing. Under repeated hammering and temperature cycling loads, the zinc plate maintains a tight fit with the steel wire through slight plastic deformation, while the geometric accuracy of the 45 steel side remains unchanged, achieving the goal of one-time processing and long-term fit.

[0037] When pulling out the double-sided wedge plate, the low friction (μ2 of 0.08~0.15) between the smooth mating surface of the 45 steel and the zinc plate ensures controllable pulling force; the zinc plate side, always in contact with the steel wire, does not need to be pulled out, avoiding the risk of secondary scratching of the steel wire surface during the zinc plate pulling process. When it is necessary to replace the zinc plate, the soft properties of zinc allow it to be easily removed along the gaps between the strands without causing mechanical damage to the steel wire.

[0038] The quenching and tempering treatment of 45 steel gives the double-sided wedge plate excellent fatigue resistance and impact resistance, and its design service life is the same as that of the main bridge structure (more than 100 years). As a sacrificial functional component, the corrosion consumption rate of zinc plate can be compensated by the thickness reserve in the design - calculated at an annual corrosion rate of 2~5μm / year, 5mm thick zinc plate can provide sufficient anti-corrosion reserve over a 100-year lifespan, and can be inspected and replaced during the bridge maintenance cycle, with full life-cycle durability characteristics.

[0039] The material selection parameters for double-sided and single-sided wedge plates are shown in Table 1.

[0040] Table 1

[0041] A design method for a combined wedge-shaped separator anti-slip device for the main cable of a suspension bridge includes the following steps: Step 1: Based on the total number of main cable strands and the length of the cable saddle area, determine the number of cable strand rows covered by each anti-skid device as m (take 3 to 4 rows) and the total number of anti-skid devices for the entire bridge as n.

[0042] Step 2: Determine the wedge half-angle θ of the double-sided wedge plate, with a value ranging from 0.5° to 2°, and the wedge half-angle β of the single-sided wedge plate, with a value ranging from 0.5° to 2°. The double-sided wedge plate must satisfy the self-locking condition. .

[0043] Step 3: Establish a wedge-shaped pressure intensification mechanical model: Force balance analysis of the double-sided wedge plate shows that the normal thrust N generated by its two sides on the single-sided wedge plate is:

[0044] Simplified to

[0045] The lateral pressure exerted by the single-sided wedge plate on the cable strand is P. lat ,

[0046] The ratio of lateral pressure to wedging force is the wedge pressure ratio K. w :

[0047] Wherein: F d For axial hammering force, The friction angle between the single-sided wedge plate and the cable strand is φ1=arctan(μ1). The friction angle between the double-sided wedge and the single-sided wedge is φ2= arctan(μ2); This allows for the generation of a large lateral clamping force with a relatively small wedging force.

[0048] Step 4: Calculate the anti-skid bearing capacity R S With anti-slip safety factor K S ,

[0049] The total anti-slip force of the entire main cable is F. anti ,

[0050] The anti-slip safety factor is K s :

[0051] Among them, F cable The total positive pressure of the main cable on the bottom of the cable saddle groove μ0 is the original friction coefficient between the cable strand and the bottom surface of the saddle groove, and μ0 is 0.25.

[0052] F slideThis represents the maximum slip force of the main cable at the saddle under design conditions. [Ks] is the allowable safety factor, which is taken as 2.0~3.0.

[0053] Step 5: Dimensional deviation compensation design, strand design gap is g o Before installation, the actual value of the cable strand gap g at each device location was measured. actual Calculate the deviation Δg = g actual -g o Based on Δg, the device positions are divided into three groups, and compensation strategies are determined for each group: Group A: Δg > +3mm, the gap is obviously too large. Increase the thickness of the single-sided wedge plate or add a thin shim to restore the initial gap to the design range; or increase the wedge depth to add lateral displacement to compensate for the gap increment.

[0054] Group B: 3mm≤Δg≤+3mm, gap deviation is within a controllable range, install according to standard procedure; fine-tune the clamping force by adjusting the wedge depth.

[0055] Group C: Δg < -3mm, the gap is obviously too small, reduce the thickness of the single-sided wedge plate to avoid exceeding the clamping force limit; at the same time, control the wedge depth and control the lateral compression within the design range.

[0056] Before installation, perform on-site measurements and determine the gap for each group: At the installation location of each group of devices, use a dedicated gap measuring tool (such as a wedge gauge set or digital vernier caliper) to measure the actual size of the cable strand gap point by point. Measurements should be taken during periods of stable main cable temperature (such as early morning or cloudy days) to eliminate the interference of temperature fluctuations on the gap. For each group of devices, measure the gap values ​​at least at the top, middle, and bottom sections, and take the average value as the actual gap g for that group. actual All measurement data are used to create a gap distribution map, which marks the measured gap value corresponding to the location of each set of devices.

[0057] For compensation strategies in Group A or Group C, various thicknesses of single-sided wedge plates (such as 8mm, 10mm, 12mm, 15mm series, etc.) and corresponding thicknesses of double-sided wedge plates are prepared during the factory prefabrication stage. On-site, the closest thickness combination is selected based on the measured gap, ensuring that the deviation between the selected total thickness and the actual gap is controlled within ±1.5mm. If the gap in Group A strategy is too large, and simply thickening the single-sided wedge plate is insufficient for complete compensation, a thin shim (such as a 1mm or 2mm stepped thickness) can be added to the back of the single-sided wedge plate. Fine adjustments using the thin shim ensure a tight fit between the mating surfaces. The thin shim is made of tempered 45 steel sheet with a finely ground surface to ensure it does not affect the frictional characteristics of the mating surfaces.

[0058] Step Six: Temperature Compensation Design, Determine the Design Reference Temperature as T designGenerally, the average annual temperature of the area where the bridge is located or the target temperature for bridge closure is taken as the reference temperature. The actual installation temperature measured during construction and installation is T. install Calculate the temperature deviation ΔT = T install -T design , The change in diameter (width) of the cable strand in the cable saddle segment caused by the temperature change ΔT is:

[0059] Where, α T The coefficient of thermal expansion of steel wire (approximately 1.2 × 10⁻⁶) -5 / ℃), L saddle Let n be the width of the strands; the corresponding wedge depth calculation formula is:

[0060] Where d is the width of the nth row of main cable strands, E c For the equivalent elastic modulus, A c Let be the cross-sectional area of ​​the n-row main cable strands. By striking the top surface of the double-sided wedge plate to increase the wedge depth, the changes in strand width caused by temperature can be compensated in real time, ensuring that the anti-slip safety factor meets the requirements under all working conditions.

[0061] For a single width change, the corresponding wedge depth compensation for the double-sided wedge plate is:

[0062] When T install > T design At this time, the cable strands are in an expanded state. After wedging to the target depth, the clamping force will decrease as the temperature drops. Therefore, when installing a single device, an additional wedging amount δT should be reserved.

[0063] For multiple devices that add wedging depth compensation cable strands, the total wedging depth compensation δ comp = ΔL T / (n w ·tanθ), where n w Let θ be the number of arrangement groups of the device along the cable saddle arc segment, and θ be the wedge half angle.

[0064] Step 7: Consider the porosity evolution compensation of the main cable, and calculate the porosity from n o (18%) Towards target value n f (9%) The diameter shrinkage caused by evolution, with reserved compensation wedge depth.

[0065] Porosity decreases from n0 to n f Change in main cable diameter ΔD:

[0066] The corresponding wedge compensation stroke for each group of devices:

[0067] Where, m cables The number of strands covered by each group of devices; Step 8: Taking into account both compensation amounts, the initial target wedging depth during the installation phase is:

[0068] Where, δ design To design the theoretical wedging depth corresponding to the clamping force, k is the phased compensation coefficient for porosity compaction, taken as 0.3~0.5, which means that 30%~50% of the porosity evolution is pre-compensated during the installation stage. The remaining part is reserved for gradual addition during the operation and maintenance stage to avoid excessive clamping force that could damage the steel wire due to over-compensation in the initial stage.

[0069] The double-sided wedge plate allows for adjustment of the wedge depth by adding or removing hammer blows, thus correcting the clamping force in real time. This adjustability enables the device to actively compensate rather than passively bear the load. The key to multi-factor compensation lies in establishing a coupled mechanical model of porosity, temperature, and clamping force. Let the porosity be n. f Temperature T install Then the main cable diameter D = f(n) f ,T install ), gap between the strands g o =g(D), equivalent wedge depth δ eff =δ actual -g o / 2*φ(θ)Clamping force P lat = h(δ eff φ(θ), where θ is the wedge half-angle, μ2 is the friction coefficient of the mating surfaces, and φ(θ) is the geometric correction coefficient related to the wedge half-angle. For small-angle wedges (θ < 5°), φ(θ) ≈ 1 can degenerate to the original formula; when θ is large, φ(θ) > 1, and the weakening effect of the gap is amplified. This model uses the macroscopically measurable temperature T install and the porosity n over a long period of time f Establishing a quantitative mapping relationship with the clamping force allows the compensation amount to be estimated theoretically or calculated back from measured data. The superposition of compensations is not a simple linear addition. Temperature fluctuations cause a rapidly changing component of the clamping force, while porosity evolution causes a slowly changing component. Appropriately setting the initial wedging depth during installation compensates for current temperature deviations while allowing for some margin for porosity compaction. This ensures that the clamping force remains above the safe threshold throughout the device's service life, preventing extreme situations such as the clamping force dropping to zero or overcompensation damaging the steel wire.

[0070] The proposed porosity and temperature coupling compensation advances anti-slip design from static section verification to full-lifetime time-varying reliability analysis, establishing a new paradigm for time-varying anti-slip design that considers material evolution (porosity compaction) and environmental effects (temperature cycling), filling the gap in the theory of full-lifetime anti-slip design for main cables of long-span suspension bridges. The clamping force attenuation caused by the main cable porosity compacting from 18% to 9% can reach 30% to 50% of the initial value. If not considered in advance during the design and installation stages, this will expose the hidden risk of insufficient anti-slip safety factor after several years of operation. This application achieves full-lifetime clamping force compensation maintenance through adjustable double-sided wedge plate insertion, fundamentally eliminating this risk and providing reliable assurance for the century-long service safety of long-span suspension bridges. The adjustable nature of this device means that anti-slip maintenance during operation only requires periodic clamping force testing and a small amount of hammering, without the need for dismantling, replacement, or large-scale construction intervention. Compared to the traditional fixed diaphragm removal and replacement scheme after failure, maintenance costs are reduced by more than an order of magnitude, and maintenance work does not affect the normal operation of the bridge.

[0071] A method for installing and adjusting a combined wedge-shaped anti-slip device for the main cable of a suspension bridge includes the following steps: Step 1: Construction Preparation and Pre-assembly Inspection Pre-installation preparation encompasses three stages: component quality inspection, contact surface treatment, and strand condition confirmation. The double-sided wedge plate's wedge angle accuracy (±0.5°), mating surface roughness (Ra≤1.6μm), and dimensional tolerances are inspected to ensure the geometric deviation between the wedge and mating surfaces is controlled within 0.1mm. The single-sided wedge plate's surface oxidation state and thickness uniformity are inspected, ensuring no obvious pits or burrs exist on the contact surface with the strand wires. Before installation, each strand surface is cleaned to remove dust, oil, and water film adhering during transportation and erection, ensuring the friction coefficient μ1 between the single-sided wedge plate and the wire remains stable within the design range of 0.4~0.6. Before installation, it must be confirmed that the strands in the target section are tightly arranged without crossing or twisting, with uniform gaps between adjacent strands, and the gap width matching the thickness of the selected single-sided wedge plate (typically 8~15 mm). If the strand gaps exhibit significant dispersion due to erection errors, the strand arrangement must be adjusted using auxiliary clamps before installing the anti-slip device.

[0072] Step Two: Graded Assembly – First, install the single-sided wedge plate, then wedge in the double-sided wedge plate. Insert the two single-sided wedge plates symmetrically into the gaps on both sides of the target strand, then push the double-sided wedge plate along the strand axis to the designed depth. This sequence is designed because the zinc plate is a soft material; placing it first allows it to naturally adhere to the wire surface under its own weight and initial positioning force, forming a preliminary contact state. When the double-sided wedge plate is subsequently wedged in, the zinc plate is already in place and its position is stable, preventing displacement or scraping of the wire due to hammering vibration.

[0073] First stage – Single-sided wedge plate placement: Insert two single-sided wedge plates into the gaps on both sides of the target strand, with the hot-sprayed zinc layer of the single-sided wedge plate facing outwards against the steel wire surface and the flat surface facing inwards as the sliding mating surface for the subsequent double-sided wedge plates. Push the single-sided wedge plate along the strand axis to the designed depth, aligning its wedge-shaped inclined surface with the wedge-shaped surface of the double-sided wedge plate. At this point, the single-sided wedge plate is in its initial zero-position state, loosely fitted with the steel wire, and no lateral clamping force has yet been generated. Figure 2 As shown.

[0074] Second stage – Axial wedging of double-sided wedge plates: Align the 45 steel quenched and tempered double-sided wedge plates with the mating surfaces of the single-sided wedge plates on both sides, and apply hammering force along the axial direction of the cable strand using a copper hammer or hydraulic impactor to slowly wedge the double-sided wedge plates in. During the wedging process, the inclined surfaces on both sides of the double-sided wedge plates simultaneously apply a normal thrust N to the single-sided wedge plates, and the single-sided wedge plates convert the normal thrust into a lateral pressure P on the cable strand. lat This achieves lateral clamping of the cable strands. During the wedging process, the hammering force and frequency must be controlled, employing a "light hammer, multiple blows, gradual pressure increase" method to avoid excessive local plastic deformation of the zinc plate or sudden changes in stress on the cable strands caused by excessive single impact. The wedging depth δ of the double-sided wedge plate and the lateral displacement Δ of the single-sided wedge plate satisfy the following geometric relationship:

[0075] The effective stroke of the wedge must meet the following requirements. .

[0076] Where: d is the width of the nth row of main cable strands, E c For the equivalent elastic modulus, A c Let be the cross-sectional area of ​​the n rows of main cables. Calculated with a wedge half-angle θ = 3°, the lateral displacement corresponding to each 1 mm wedge depth is 0.052 mm, which can indirectly achieve precise control of the lateral clamping force in the cable saddle area.

[0077] Step 3: Clamping Force Monitoring and Wedging Depth Control During installation, the lateral clamping force or equivalent wedging depth must be monitored in real time to ensure that the design target is achieved. Real-time monitoring can be performed using one of the following methods: ① Direct measurement method for wedging depth: Mark the scale lines on the side of the double-sided wedging plate, measure the exposed length of the wedging with vernier calipers, calculate the wedging depth δ, and then convert it into lateral pressure P. lat .

[0078] ② Strain monitoring method: Strain gauges are attached to the surface of a single-sided or double-sided wedge plate, and the actual contact pressure is calibrated by strain readings.

[0079] ③ Cable strand displacement monitoring method: Use a dial indicator to measure the lateral compression deformation of the cable strands to indirectly verify the clamping force.

[0080] The upper limit of the wedge depth control must satisfy Δ ≤ δ cable + δ gap (The sum of the elastic compression of the cable strands and the assembly gap) prevents excessive wedging, which could lead to residual compressive stress in the steel wire or complete crushing of the zinc plate. After reaching the target wedging depth, the double-sided wedge plate should meet the self-locking condition θ≤ arctan(μ2), that is, it should not automatically withdraw after the hammering force is removed, and the clamping force of the device should remain stable.

[0081] Step 4: Temperature Compensation and Dynamic Adjustment The main cable wires are significantly affected by temperature. The difference between the closure temperature and the operating temperature will cause thermal expansion and contraction of the cable strands, resulting in a drift of the applied clamping force. Specifically, the following occurs: temperature change → thermal expansion and contraction of the main cable strands → change in the dimensions (longitudinal + transverse + vertical) of the main cable strands at the cable saddle → change in the radial pressure distribution of the strands in the saddle groove → change in the contact state between the single-sided wedge plate and the strands → change in the applied transverse clamping force.

[0082] Temperature compensation adjustment is a crucial step in the installation process. The drift in clamping force caused by thermal expansion and contraction of the cable strands can be compensated for by re-hammering the double-sided wedge plates to increase the wedging depth—this repeatable adjustment feature is a significant advantage of this device compared to traditional fixed baffles. Installation and adjustment must be performed in conjunction with temperature compensation.

[0083] When the installation temperature T install Compared with the design reference temperature T design When a deviation exists, the compensation amount δ is used. comp Increase the wedge depth by hammering (increasing force) or loosen the double-sided wedge slightly (reducing force) to calibrate the clamping force to the design value. However, in actual operation, removing the double-sided wedge requires overcoming the self-locking friction (θ≤arctan(μ2)). When removing the double-sided wedge, inject grease between the wedge mating surfaces for lubrication and use a special pulling tool. After each adjustment, maintain the pressure and observe for no less than 15 minutes.

[0084] Step 5: Bridge Completion Acceptance and Operation Maintenance During the bridge completion phase, all combined wedge-shaped anti-slip devices underwent full acceptance testing. The actual wedging depth, corresponding clamping force reading, and ambient temperature of each device were recorded to create an installation file. During operation and maintenance, the devices were regularly inspected for loosening, rust, or excessive corrosion of the zinc plates. If the clamping force was found to have decreased beyond the design allowable range, it could be compensated for by re-hammering the double-sided wedge plates to increase the wedging depth.

[0085] The operational compensation strategy is divided into three phases: Phase 1 (1-2 years after bridge completion): During this phase, the porosity rapidly decreases from 18% to 12%-14%, and the main cable diameter shrinkage rate is relatively large. During this phase, the clamping force is checked quarterly. If the attenuation exceeds the limit, the wedging depth is increased, and the amount of each increase is calculated by reverse calculation based on the measured deviation.

[0086] Phase Two (3-10 years after bridge completion): The porosity slowly decreases from 12% to 10%, and the shrinkage rate slows down. During this phase, inspections should be conducted every six months to one year, and adjustments should be made according to the annual maintenance plan.

[0087] Phase 3 (10 years after bridge completion): Porosity approaches 9%, with extremely slow changes. This phase is included in routine inspections, conducted every 2-3 years.

[0088] After each compensation adjustment, the pressure must be stabilized and observed for no less than 15 minutes. Once it is confirmed that the clamping force has not significantly loosened, it should be locked, and the actual wedging depth, clamping force reading, and temperature data should be recorded to establish a clamping force evolution archive for the entire life cycle. This provides measured data support for the design of subsequent similar projects. This repeatable adjustment feature is a significant advantage of this device compared to traditional welded or bolted baffles, enabling full-life-cycle maintainability of the main cable's anti-slip performance.

[0089] The inclined pressure mechanism of the double-sided wedge plate can obtain several to tens of times the lateral clamping force with a small axial hammering force, and the clamping force can be precisely applied and graded controlled by controlling the wedge depth.

[0090] The friction coefficient μ1 between the single-sided wedge plate and the cable strand contact surface is 0.5~0.7, ensuring the clamping effect; the friction coefficient μ2 between the double-sided wedge plate and the single-sided plate mating surface is 0.08~0.15, ensuring smooth wedge insertion and quick extraction after construction, achieving anti-slip performance and construction convenience.

[0091] The single-sided wedge plate utilizes the soft properties of zinc to adapt to the micro-unevenness of the steel wire surface through plastic deformation, avoiding stress concentration and steel wire damage; at the same time, it utilizes the sacrificial anode effect of zinc to provide cathodic protection for the main cable.

[0092] By repeatedly wedging in and out to adjust the clamping force, the technical challenge of traditional fixed diaphragms being unable to adapt to temperature changes and porosity evolution was solved. The porosity and temperature coupled compensation design advances the anti-slip design from static section verification to full-life time-varying reliability analysis, filling the gap in the theory of full-life anti-slip design for main cables of long-span suspension bridges.

[0093] By first installing a single-sided wedge plate and then wedging in a double-sided wedge plate, scraping of the steel wire is avoided during installation; the dimensional deviation grouping compensation strategy effectively adapts to manufacturing deviations in the main cable diameter and saddle width, enabling the device to adapt to actual engineering errors.

[0094] During the operational phase, maintenance only requires periodic checks of clamping force and a small amount of additional hammering. No dismantling, replacement, or large-scale construction intervention is required. Maintenance work does not affect the normal operation of the bridge, and maintenance costs are reduced by more than an order of magnitude compared to traditional solutions.

[0095] In addition to the above embodiments, the present invention also includes other embodiments. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of the present invention.

Claims

1. A method for installing and adjusting a combined wedge-shaped anti-slip device for the main cable of a suspension bridge, characterized in that: The method includes the following steps: Step 1: Inspect the wedge angle accuracy, mating surface roughness, and dimensional tolerance of the double-sided wedge plate; inspect the surface condition and thickness uniformity of the single-sided wedge plate; clean the strand surface; and confirm the strand arrangement. Step 2: First, insert two single-sided wedge plates symmetrically into the gaps on both sides of the target strand. Then, align the double-sided wedge plate with the mating surfaces of the single-sided wedge plates on both sides. Apply hammering force along the axial direction of the strand to wedge the double-sided wedge plate in. Use a light hammer with multiple blows and a gradual pressure increase method. The wedge depth δ of the double-sided wedge plate and the lateral displacement Δ of the single-sided wedge plate satisfy Δ = δ·tanθ to achieve lateral clamping of the strand. Step 3: During installation, monitor the lateral clamping force or wedging depth in real time to ensure that the wedging depth meets the requirement of Δ ≤ δ. cable +δ gap After reaching the target wedge depth, the double-sided wedge plate should satisfy the self-locking condition θ ≤ arctan(μ2); where δ cable δ represents the elastic compression of the cable strand. gap This is for assembly clearance; Step 4: Record the installation temperature T at the start of construction. install and the design reference temperature T design For comparison, when T install >T design When calculating the temperature deviation ΔT = T install - T design The change in diameter of the cable strand in the cable saddle section caused by the temperature change ΔT is: ； α T L is the coefficient of linear expansion of the steel wire. saddle The width of the main cable in the saddle arc section; To restore the target clamping force, the wedging depth compensation δ is used. comp To compensate for the change in the diameter of the strands; ； The clamping force can be corrected in real time by adjusting the wedge depth by adding hammer blows or removing the double-sided wedge plate; When removing the double-sided wedge plate, inject grease between the wedge mating surfaces and pull it out. Step 5: During the bridge completion acceptance, record the actual wedging depth, clamping force reading, and ambient temperature of each set of devices to form an installation file. During the operation period, inspection and compensation maintenance shall be carried out in the following stages: once a quarter for 1-2 years after bridge completion, once every 6 months to 1 year for 3-10 years after bridge completion, and once every 2-3 years after 10 years after bridge completion; after each compensation adjustment, the pressure stabilization observation shall be no less than 15 minutes and the data shall be recorded to establish a clamping force evolution file for the entire life cycle.

2. The method for installing and adjusting a combined wedge-shaped isolation plate anti-slip device for the main cable of a suspension bridge according to claim 1, characterized in that: Step three involves using a direct wedge depth measurement method, a strain monitoring method, or a cable strand displacement monitoring method to monitor the lateral clamping force or wedge depth in real time.

3. The method for installing and adjusting a combined wedge-shaped isolation plate anti-slip device for the main cable of a suspension bridge according to claim 1, characterized in that: In step three: ； Where d is the width of the nth row of main cable strands, E c For the equivalent elastic modulus, A c Let be the cross-sectional area of ​​the n-row main cable strands.

4. The method for installing and adjusting a combined wedge-shaped isolation plate anti-slip device for the main cable of a suspension bridge according to claim 1, characterized in that: Before construction, consider the porosity from the initial value n. o Towards target value n f The diameter shrinkage caused by evolution requires a reserve for wedge depth compensation: ； Where ΔD is the change in main cable diameter caused by the change in porosity, in meters. cables This represents the number of cable strands covered by each group of devices.

5. The method for installing and adjusting a combined wedge-shaped separator anti-slip device for the main cable of a suspension bridge according to claim 4, characterized in that: ； Among them, D o The initial diameter of the main cable.

6. The method for installing and adjusting a combined wedge-shaped separator anti-slip device for the main cable of a suspension bridge according to claim 5, characterized in that: The initial target wedge depth for the installation phase in step two: ； δ design To design the theoretical wedging depth corresponding to the clamping force, k is the staged compensation coefficient for porosity compaction.

7. The method for installing and adjusting a combined wedge-shaped isolation plate anti-slip device for the main cable of a suspension bridge according to claim 1, characterized in that: Before installation, the actual value of the cable spacing g at each device location was measured. actual The design gap of the cable strand is g. o Calculate the deviation Δg = g actual -g o Based on Δg, the device positions are divided into three groups, and compensation strategies are determined for each group: Group A: Δg > +3mm, increase the thickness of the single-sided wedge plate; Group B: 3mm≤Δg≤+3mm, install according to standard procedure; Group C: Δg < -3mm, reduce the thickness of the single-sided wedge and control the wedge depth.

8. The method for installing and adjusting a combined wedge-shaped isolation plate anti-slip device for the main cable of a suspension bridge according to claim 1, characterized in that: The friction coefficient μ1 between the single-sided wedge plate and the contact surface of the stranded steel wire is 0.5~0.7; the friction coefficient μ2 between the mating surfaces of the double-sided wedge plate and the single-sided wedge plate is 0.08~0.

15.

9. The method for installing and adjusting a combined wedge-shaped separator anti-slip device for the main cable of a suspension bridge according to claim 1, characterized in that: The double-sided wedge plate is made of steel of grade 45 or higher, and the single-sided wedge plate is made of pure zinc plate or other soft materials.

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