A construction method for modifying the main tower cable saddle of an old bridge for cable replacement

Abstract

This invention relates to a construction method for the main tower cable saddle modification of an old bridge, belonging to the technical field of low-tower cable-stayed bridge construction. Step 1: Fabricate a special-shaped split-wire cable saddle, the bending radius of which is consistent with the bending radius of the outer tube of the double-tube cable saddle. Step 2: Remove the inner tube, anti-slip clamp, and anti-slip anchor of the double-tube cable saddle, remove the epoxy mortar inside the anti-slip anchor, and clean impurities from the outer tube of the double-tube cable saddle. Step 3: Insert the special-shaped split-wire cable saddle into the outer tube of the double-tube cable saddle, ensuring that the exposed tower wall lengths at both ends of the special-shaped split-wire cable saddle are the same. Step 4: Positioning plates are provided at both ends of the special-shaped split-wire cable saddle, and these positioning plates are connected to the corresponding pads on the double-tube cable saddle. This application features a split-wire pipe, achieving uniform stress distribution while using small construction equipment to replace, tension, and adjust individual cable strands of the cable stays. Furthermore, high-strength mortar is not required at both ends of the cable saddle, facilitating later maintenance and replacement of the cable stays.

Description

Technical Field

[0001] This invention relates to a construction method for the main tower cable saddle renovation of an old bridge, belonging to the field of construction technology for low-tower cable-stayed bridges. Background Technology

[0002] As the main load-bearing component on the tower of a low-tower cable-stayed bridge, the cable saddle is embedded inside the main tower. After the steel strand stay cables pass through the cable saddle embedded in the main tower, they are anchored to the main beams on both sides of the bridge tower. In some early low-tower cable-stayed bridge projects, due to technical limitations, the cable saddle adopted a double-tube structure. The outer tube of the cable saddle was embedded in the concrete main tower, and the inner tube was filled with high-strength epoxy mortar to bond the steel strands of the cable saddle section to the inner tube as a whole.

[0003] The cable-stayed bridge with low towers adopts a double-sleeve cable saddle structure, such as... Figure 1 , 2 As shown, the following problems exist:

[0004] 1) All the steel strands inside the cable saddle are stacked and squeezed together, which is unfavorable for the steel strands and cable saddle, resulting in stress concentration.

[0005] 2) The stay cables are bonded together as a whole inside the main tower saddle due to the grout, making it impossible to replace individual strands. Large jacks are needed to release the stay cables as a whole and cut the bundle, which is inconvenient.

[0006] 3) During cable replacement, it is necessary to forcefully remove the anchor cylinders, anti-slip cable clamps and mortar at both ends of the cable saddle, and dismantle the inner tube of the cable saddle and the steel strands of the cable saddle section as a whole. The dismantling is difficult and poses safety risks. Traffic control requirements are high during the construction period.

[0007] 4) It cannot be replaced using existing split-wire cable saddle technology. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a construction method for the main tower cable saddle renovation of old bridge cable replacement, which has the function of splitting the cable into pipes. While ensuring uniform stress, it can realize the functions of single cable replacement, tensioning and adjustment of cable strands using small construction equipment. Moreover, there is no need to pour high-strength mortar at both ends of the cable saddle, which facilitates the later maintenance and replacement of the cable.

[0009] The technical solution adopted by this invention to solve the above problems is as follows: a construction method for the main tower cable saddle renovation of an old bridge, the construction method being based on a special-shaped split-wire cable saddle, the special-shaped split-wire cable saddle comprising a plurality of special-shaped split-wire tubes, the plurality of special-shaped split-wire tubes being stacked in layers, with steel strands respectively threaded through the special-shaped split-wire tubes; each special-shaped split-wire tube includes an arc segment, with a straight middle section and a straight lower section symmetrically arranged on both sides of the arc segment, the straight middle section being located between the arc segment and the straight lower section; both ends of the arc segment are respectively connected to one end of the straight middle section with an arc transition, the other end of the straight middle section is respectively connected to the top end of the corresponding straight lower section with an arc transition, and the bottom ends of the two straight lower sections are connected with an arc transition.

[0010] The construction method includes the following steps:

[0011] Step 1: Fabricate a special-shaped split-wire cable saddle, the bending radius of which is consistent with the bending radius of the outer tube of the double-sleeve cable saddle;

[0012] Step 2: Remove the inner tube, anti-slip cable clamp, and anti-slip anchor cylinder of the double-sleeve cable saddle; remove the epoxy mortar inside the anti-slip anchor cylinder; and clean the impurities inside the outer tube of the double-sleeve cable saddle.

[0013] Step 3: Insert the irregularly shaped split-wire cable saddle into the outer tube of the double-sleeve cable saddle, ensuring that the exposed tower wall lengths at both ends of the irregularly shaped split-wire cable saddle are the same.

[0014] Step 4: The outer tube axis of the shaped split-wire cable saddle coincides with that of the double-tube cable saddle. Positioning plates are provided at both ends of the shaped split-wire cable saddle, and the positioning plates are connected to the pads on the corresponding sides of the double-tube cable saddle.

[0015] Step 5: Install a grouting pipe on one of the positioning plates and an exhaust pipe on the other positioning plate; the gaps between the grouting pipe, the exhaust pipe and the special-shaped split wire cable saddle and the outer pipe are connected;

[0016] Step Six: The filler is injected into the gap between the special-shaped split wire cable saddle and the outer pipe through the grouting pipe. After the filler has cured, the modification of the main tower cable saddle is completed.

[0017] The included angle between the middle segments of the two straight lines is 55-65°, and the included angle between the lower segments of the two straight lines is 115-125°.

[0018] The shaped wire-splitting tube is made of stainless steel.

[0019] The thickness of the shaped splitting tube is 1-3 mm.

[0020] The filler is a high-strength slurry.

[0021] The positioning plate has an inner hole at its center; the inner side of the positioning plate is provided with a centering boss, which is located inside the outer tube of the double-sleeve cable saddle; the positioning plate also has an exhaust hole and a grouting hole.

[0022] The shape of the inner hole of the positioning plate matches the shape of several irregularly shaped split wire tubes stacked in layers.

[0023] The PE sheath of the special-shaped split wire cable saddle section steel strand is removed and covered with an anti-slip layer.

[0024] The thickness of the anti-slip layer is ≥0.5mm, and the friction coefficient μ between the anti-slip layer and the cable saddle is ≥0.3.

[0025] The outer diameter of the irregularly shaped split-wire cable saddle is smaller than the inner diameter of the outer tube of the double-sleeve cable saddle.

[0026] Compared with the prior art, the advantages of the present invention are: a construction method for the main tower cable saddle modification of an old bridge with cable replacement;

[0027] 1. The dimensions of the special-shaped split-wire cable saddle are about 15% smaller than those of the conventional split-wire cable saddle. The outer diameter of the special-shaped split-wire cable saddle is smaller than the inner diameter of the outer tube of the double-sleeve cable saddle, which meets the installation requirements.

[0028] 2. After grouting is injected between the special-shaped split-wire cable saddle and the outer pipe of the original double-sleeve cable saddle of the main tower, it is solidified into a permanent embedded part, so that the cable saddle can be modified without affecting the structural form of the tower.

[0029] 3. The special-shaped split wire tube cable saddle can realize the requirements of single cable replacement, single cable tensioning, and single cable adjustment. Moreover, each steel strand in the special-shaped split wire tube corresponds to an independent cable passage. The steel strands do not interfere with each other and are parallel to each other, resulting in more reasonable stress distribution.

[0030] 4. The tensioning equipment is lighter and more convenient. The pretensioning, adjustment and release of the stay cables are all carried out using a single-hole jack. During the cable replacement construction, the requirements for traffic control are lower.

[0031] 5. The PE sheath of the steel strand in the special-shaped wire-splitting tube cable saddle section is removed and covered with an anti-slip layer to increase the friction between the special-shaped wire-splitting tube and the steel strand to resist the unbalanced force on both sides of the main tower and prevent the cable stays from sliding relative to each other. There is no need to install anti-slip components or inject epoxy mortar in the anti-slip anchor cylinder. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the original double-sleeve cable saddle and the anti-skid devices on both sides of the cable saddle.

[0033] Figure 2 This is a schematic diagram of the cross-section of the original double-sleeve cable saddle.

[0034] Figure 3This is a schematic diagram illustrating the modification of the main tower cable saddle for cable replacement in an old bridge according to an embodiment of the present invention;

[0035] Figure 4 for Figure 3 A schematic diagram of the cross-section;

[0036] Figure 5 This is a schematic diagram of the cross-section of a non-standard wire-splitting cable saddle.

[0037] Figure 6 This is a schematic diagram of the cross-section of a non-woven wire tube;

[0038] Figure 7 for Figure 1 A schematic diagram showing the removal of the inner tube, steel strands, and anti-slip anchor cylinder from the double-sleeve cable saddle.

[0039] Figure 8 A schematic diagram showing the insertion of a non-standard split-wire cable saddle into the outer tube of a double-sleeve cable saddle;

[0040] Figure 9 This is a schematic diagram of the positioning plate installation.

[0041] Figure 10 This is a schematic diagram of the positioning plate;

[0042] Figure 11 This is a side view of the positioning plate;

[0043] Figure 12 This is a schematic diagram of the installation of the grouting pipe and the vent pipe;

[0044] The diagram shows: 1. Double-sleeve cable saddle, 1.1 outer tube, 1.2 inner tube, 1.3 pad plate, 2. anti-slip anchor cylinder, 3. anti-slip cable clamp, 4. epoxy mortar, 5. steel strand, 6. special-shaped split-wire cable saddle, 6.1 special-shaped split-wire tube, 6.11 arc segment, 6.12 straight middle section, 6.13 straight lower section, 7. high-strength grout, 8. positioning plate, 8.1 vent hole, 8.2 positioning plate inner hole, 8.3 grouting hole, 8.4 screw hole, 8.5 centering boss, 9. anti-slip layer, 10 grouting pipe, 11. vent pipe. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0046] This embodiment describes a construction method for modifying the main tower cable saddle of an old bridge undergoing cable replacement. This method is based on a non-standard wire-splitting cable saddle 6. For example... Figure 5 As shown, the saddle 6 consists of several shaped wire-splitting tubes 6.1, each containing a steel strand 5. These shaped wire-splitting tubes 6.1 are stacked and welded together. Figure 6As shown, the shaped wire-splitting tube 6.1 includes an arc segment 6.11. A straight middle section 6.12 and a straight lower section 6.13 are symmetrically arranged on both sides of the arc segment 6.11. The straight middle section 6.12 is located between the arc segment 6.11 and the straight lower section 6.13. Both ends of the arc segment 6.11 are respectively connected to one end of the corresponding straight middle section 6.12 with an arc transition. The other end of the straight middle section 6.12 is respectively connected to the top end of the corresponding straight lower section 6.13 with an arc transition. The bottom ends of the two straight lower sections 6.13 are also connected with an arc transition.

[0047] The angle between the midpoints 6.12 of the two straight lines is 60°, and the angle between the lower segments 6.13 of the two straight lines is 120°.

[0048] The special-shaped wire splitting tube is made of stainless steel and has a thickness of 1-3mm.

[0049] A construction method for modifying the main tower cable saddle of an old bridge for cable replacement includes the following steps:

[0050] Step 1: Fabricate the irregularly shaped split-wire cable saddle 6. The bending radius of the irregularly shaped split-wire cable saddle 6 is consistent with the bending radius of the outer tube 1.1 of the double-sleeve cable saddle 1.

[0051] Step Two: As Figure 7 As shown, the inner tube 1.2, anti-slip cable clamp 3, and anti-slip anchor cylinder 2 of the double-sleeve cable saddle 1 are removed, the epoxy mortar 4 inside the anti-slip anchor cylinder 2 is removed, and the impurities inside the outer tube 1.1 of the double-sleeve cable saddle 1 are cleaned.

[0052] Step 3: As Figure 8 As shown, the irregularly shaped split-wire cable saddle 6 is inserted into the outer tube 1.1 of the double-sleeve cable saddle, and the length of the irregularly shaped split-wire cable saddle 6 exposed on both sides of the tower wall is consistent.

[0053] Step 4: The outer tube 1.1 of the irregular wire splitting saddle 6 and the double-sleeve saddle 1 are aligned. Positioning plates 8 are provided on both sides of the irregular wire splitting saddle 6. The positioning plates 8 are fixedly connected to the corresponding pads 1.3 of the double-sleeve saddle 1 by screws. Sealant is applied to the joint between the irregular wire splitting saddle 6 and the positioning plates 8.

[0054] like Figure 9 , 10 As shown in Figure 11, the positioning plate 8 has an inner hole 8.2 at its center, the shape of which matches the shape of the stacked irregularly shaped wire tubes 6.1. The inner surface of the positioning plate 8 has a centering boss 8.5, which is located inside the outer tube 1.1 of the double-sleeve cable saddle 1. The positioning plate 8 also has an vent hole 8.1 and a grouting hole 8.3. Multiple circumferentially distributed screw holes 8.4 are also provided on the positioning plate 8.

[0055] Step 5: As Figure 12As shown, a grouting hole 8.3 is connected to a grouting pipe 10, and an exhaust hole 8.1 is connected to an exhaust pipe 11; the gaps between the grouting pipe 10, the exhaust pipe 11 and the special-shaped split wire cable saddle 6 and the outer pipe 1.1 are connected.

[0056] Step Six: As Figure 3 , 4 As shown, high-strength grout is injected through grouting pipe 8.3 into the gap between the special-shaped split wire cable saddle 6 and the outer pipe 1.1. After the high-strength grout has cured, the modification of the main tower cable saddle is completed.

[0057] The installation steps for step three above are as follows:

[0058] a. With the assistance of a tower crane, the irregularly shaped split-wire cable saddle 6 is hoisted to the tower end operating platform using a hoisting sling.

[0059] b. Take a traction rope, the length of which is about 3 times the length of the 6-shaped split-wire cable saddle.

[0060] c. Pass the traction rope through one side of the double-sleeve cable saddle outer tube 1.1 to the other side, and then through one of the special-shaped wire tubes 6.1 in the middle part of the special-shaped wire tube cable saddle 6. Install a limiting plate at the end of the special-shaped wire tube cable saddle 6. The limiting plate has a hole through which the traction rope can pass. Pass the traction rope through this hole and tie the limiting steel bar at the end of the traction rope.

[0061] d: An electric hoist or a manual hoist is installed at the beginning of the traction rope.

[0062] e: Align the end of the shaped split-wire cable saddle with the outer tube opening of the double-sleeve cable saddle.

[0063] f: Start the electric or manual hoist at the beginning of the traction rope and slowly pull the special-shaped split wire saddle into the outer tube of the double-tube saddle.

[0064] h: Remove the tower crane hoisting belt and continue pulling the special-shaped wire-split cable saddle until it passes through and exposes the outer tube of the double-sleeve cable saddle. Measure the exposed length of both ends of the special-shaped wire-split cable saddle, mark the position, and ensure that the exposed length of the special-shaped wire-split cable saddle on both sides of the tower wall is consistent.

[0065] g: Remove auxiliary installation tools such as traction ropes and limit plates.

[0066] The specific steps for step four above are as follows:

[0067] a: Insert the hoisting rope into the middle of the top row of the special-shaped split tube saddle;

[0068] b: Positioning plates on both sides of the saddle of the special-shaped split wire tube are in place and the hoisting rope is passed through;

[0069] c: Install electric or manual hoists on both sides of the special-shaped wire splitting pipe saddle, and fasten the two ends of the hoisting rope to the hoist hook;

[0070] e: Start the electric hoists or manual hoists on both sides at the same time to lift the special-shaped wire splitting saddle. When the special-shaped wire splitting saddle and the outer tube axis of the double-tube saddle are aligned, install the positioning plate in place (the ends of several special-shaped wire splitting tubes are respectively set in the inner hole of the positioning plate, and the centering boss is locked in the outer tube of the double-tube saddle), and fix the positioning plate to the double-tube saddle pad with screws.

[0071] After completing step six above, the steel strands are threaded into the corresponding special-shaped wire-splitting tubes 6.1. The PE sheath of the steel strands in the saddle section of the special-shaped wire-splitting tube is removed and covered with an anti-slip layer 9. The thickness of the anti-slip layer 9 is ≥0.5mm, and the coefficient of friction μ between the anti-slip layer 9 and the saddle is ≥0.3. Anti-slip anchors are installed on the outer side of the positioning plate, ensuring that both ends of the special-shaped wire-splitting tube saddle are positioned within the corresponding anti-slip anchors. The anti-slip layer on the steel strands in the saddle section of the special-shaped wire-splitting tube increases the anti-slip force on both sides of the saddle, eliminating the need to install anti-slip components or inject epoxy mortar inside the anti-slip anchors.

[0072] The dimensions of the special-shaped split-wire cable saddle are about 15% smaller than those of the conventional split-wire cable saddle. The outer diameter of the special-shaped split-wire cable saddle is smaller than the inner diameter of the outer tube of the double-sleeve cable saddle, which meets the installation requirements.

[0073] After grouting is injected between the irregularly shaped split-wire cable saddle and the outer pipe of the original double-sleeve cable saddle of the main tower, it is solidified into a permanent embedded part, and the cable saddle can be modified without affecting the structural form of the tower.

[0074] The special-shaped split-wire tube cable saddle can meet the requirements of single cable replacement, single cable tensioning, and single cable adjustment. Moreover, each steel strand in the special-shaped split-wire tube corresponds to an independent cable passage. The steel strands do not interfere with each other and are parallel to each other, resulting in more reasonable stress distribution.

[0075] The tensioning equipment is lighter and more convenient. The pretensioning, adjustment and release of the stay cables are all carried out using single-hole jacks, and the traffic control requirements are lower during the cable replacement construction.

[0076] The PE sheath of the steel strand in the special-shaped split tube cable saddle section is removed and covered with an anti-slip layer to increase the friction between the special-shaped split tube and the steel strand to resist the unbalanced force on both sides of the main tower and prevent the cable from sliding relative to each other. There is no need to install anti-slip components or inject epoxy mortar in the anti-slip anchor cylinder.

[0077] 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 construction method for modifying the main tower cable saddle of an old bridge for cable replacement, characterized in that: The construction method is based on a special-shaped split-wire cable saddle, which includes several special-shaped split-wire tubes arranged in layers, with steel strands threaded through each tube. Each split-wire tube includes an arc segment, with a straight middle section and a straight lower section symmetrically arranged on both sides. The straight middle section is located between the arc segment and the straight lower section. Both ends of the arc segment are connected to one end of the straight middle section by an arc transition, and the other end of the straight middle section is connected to the top of the corresponding straight lower section by an arc transition. The bottom ends of the two straight lower sections are connected by an arc transition. The construction method includes the following steps: Step 1: Fabricate a special-shaped split-wire cable saddle, the bending radius of which is consistent with the bending radius of the outer tube of the double-sleeve cable saddle; Step 2: Remove the inner tube, anti-slip cable clamp, and anti-slip anchor cylinder of the double-sleeve cable saddle; remove the epoxy mortar inside the anti-slip anchor cylinder; and clean the impurities inside the outer tube of the double-sleeve cable saddle. Step 3: Insert the irregularly shaped split-wire cable saddle into the outer tube of the double-sleeve cable saddle, ensuring that the exposed tower wall lengths at both ends of the irregularly shaped split-wire cable saddle are the same. Step 4: The outer tube axis of the shaped split-wire cable saddle coincides with that of the double-tube cable saddle. Positioning plates are provided at both ends of the shaped split-wire cable saddle, and the positioning plates are connected to the pads on the corresponding sides of the double-tube cable saddle. Step 5: Install a grouting pipe on one of the positioning plates and an exhaust pipe on the other positioning plate; the gaps between the grouting pipe, the exhaust pipe and the special-shaped split wire cable saddle and the outer pipe are connected; Step Six: The filler is injected into the gap between the special-shaped split wire cable saddle and the outer pipe through the grouting pipe. After the filler has cured, the modification of the main tower cable saddle is completed.

2. The construction method for the main tower cable saddle renovation of an old bridge according to claim 1, characterized in that: The included angle between the middle segments of the two straight lines is 55~65°, and the included angle between the lower segments of the two straight lines is 115~125°.

3. The method for modifying the main tower cable saddle of an old bridge according to claim 1, characterized in that: The shaped wire-splitting tube is made of stainless steel.

4. The construction method for modifying the main tower cable saddle of an old bridge according to claim 1, characterized in that: The thickness of the shaped splitting tube is 1-3 mm.

5. The construction method for modifying the main tower cable saddle of an old bridge according to claim 1, characterized in that: The filler is a high-strength slurry.

6. The construction method for modifying the main tower cable saddle of an old bridge according to claim 1, characterized in that: The positioning plate has an inner hole at its center; the inner side of the positioning plate is provided with a centering boss, which is located inside the outer tube of the double-sleeve cable saddle; the positioning plate also has an exhaust hole and a grouting hole.

7. The construction method for modifying the main tower cable saddle of an old bridge according to claim 6, characterized in that: The shape of the inner hole of the positioning plate matches the shape of several irregularly shaped split wire tubes stacked in layers.

8. The construction method for the main tower cable saddle renovation of an old bridge according to claim 1, characterized in that: The PE sheath of the special-shaped split wire cable saddle section steel strand is removed and covered with an anti-slip layer.

9. A construction method for modifying the main tower cable saddle of an old bridge according to claim 8, characterized in that: The thickness of the anti-slip layer is ≥0.5mm, and the friction coefficient between the anti-slip layer and the cable saddle is µ≥0.

3.

10. The construction method for modifying the main tower cable saddle of an old bridge according to claim 1, characterized in that: The outer diameter of the irregularly shaped split-wire cable saddle is smaller than the inner diameter of the outer tube of the double-sleeve cable saddle.

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