Reverse pre-topping type anchorage and construction method thereof

Abstract

The application discloses a reverse pre-jacking type anchorage and a construction method thereof, and relates to the field of suspension bridge anchorage structures. The specific construction method comprises the following steps: placing a gravity anchorage in a bedrock; arranging at least one jacking device between the gravity anchorage and the bedrock near one end of the gravity anchorage close to a bridge tower; calculating the friction force f between the bottom of the gravity anchorage and the bedrock; jacking the gravity anchorage by the jacking device with a force F, wherein the component of F in the direction opposite to the direction of f is not greater than f; and connecting a main cable to the gravity anchorage. The jacking device is arranged between the gravity anchorage and the bedrock, so that the gravity anchorage reserves friction force in the direction of the main cable tension, and the friction force and the jacking force can jointly resist the horizontal tension of the main cable when the main cable pulls the gravity anchorage, thereby reducing the friction force requirement of the gravity anchorage, and thus reducing the size of the anchorage, thereby reducing the engineering quantity of the anchorage construction.

Description

Technical Field

[0001] This invention relates to the field of suspension bridge anchorage structures, and particularly to a reverse pre-jacking anchorage and its construction method. Background Technology

[0002] Suspension bridges are among the bridge types with the greatest span capacity, mainly composed of three parts: main cables, bridge towers, and anchorages. Anchorages are mainly used to secure the main cables and transfer the force of the main cables to the foundation, and are key components that determine the overall stability of the suspension bridge.

[0003] Currently, commonly used anchorage structures include gravity anchorages, tunnel anchorages, and rock anchorages. Gravity anchorages are the most common type, primarily relying on their own weight to bear the vertical component of the main cable and the friction between them and the ground to bear the horizontal component. Horizontal anti-slip design is typically a key aspect of anchorage design. However, existing technologies have the following problems:

[0004] (1) As the bridge span and load increase, the load transmitted by the main cable becomes larger and larger. Existing design specifications only consider the friction between the bottom of the anchor and the base to resist the horizontal component of the main cable. The friction can only be increased by increasing the weight of the anchor, resulting in a huge anchor volume and thus increasing the amount of work.

[0005] (2) When the bedrock has good lithology, the bottom of the anchor is sometimes designed as a toothed type and the front edge is designed as a stepped type in order to utilize the horizontal resistance of the bedrock to the anchor. However, due to the lack of relevant specifications and research data, it is impossible to calculate the force that the above design can provide. The design only regards this part of the force as a safety reserve. At the same time, this part of the horizontal force is also a passive force transmission. The anchor must be displaced and the two squeeze each other to play a role. However, if displacement occurs, other construction data need to be changed accordingly. Summary of the Invention

[0006] In view of the deficiencies in the existing technology, the technical problem solved by the present invention is: how to reduce the amount of engineering work in anchorage construction.

[0007] To achieve the above objectives, the present invention provides a construction method for a reverse pre-jacking anchorage, comprising the following steps:

[0008] Place gravity anchors in the bedrock;

[0009] At least one jacking device is installed between the end of the gravity anchor near the bridge tower and the bedrock;

[0010] Calculate the frictional force f between the bottom of the gravity anchor and the bedrock;

[0011] The jacking device jacks the gravity anchor with a force F, wherein the component of F in the direction opposite to f is no greater than f;

[0012] The main cable is connected to the gravity anchor.

[0013] Based on the above technology, after the jacking device pushes the gravity anchor with a force F, and before connecting the main cable to the gravity anchor, the following steps are also included:

[0014] The space between the end of the gravity anchor near the bridge tower and the bedrock is divided into a first area and a second area. The first area is used to place the jacking device.

[0015] Concrete is poured in the second area to form a post-cast strip.

[0016] Based on the above technology, after the post-cast strip is formed, the following steps are also included: removing the jacking device.

[0017] Based on the above technology, the jacking device pushes the gravity anchor with a force F, specifically including the following steps:

[0018] The jacking force of the jacking device on the gravity anchor gradually increases from 0 until it reaches F, and the direction of the jacking force is the same as the opposite direction of the horizontal tension of the main cable, or the direction of the jacking force forms an acute angle with the opposite direction.

[0019] Based on the above technology, at least one jacking device is installed between the end of the gravity anchor near the bridge tower and the bedrock, specifically including the following steps:

[0020] By calculating and setting several jacking points at the end of the anchor foundation of the gravity anchor near the bridge tower, several jacking devices are installed on the bedrock, and the number of jacking devices matches the number of jacking points.

[0021] Based on the above technology, the following steps are also included before placing the gravity anchor in the bedrock:

[0022] A pit is dug in the bedrock at the predetermined location of the gravity anchor. The longitudinal length of the pit is greater than the longitudinal length of the gravity anchor, so that there is space between the gravity anchor and the bedrock to install a jacking device.

[0023] Based on the above-mentioned technology, the reverse pre-jacking anchorage provided by the present invention is characterized in that it comprises:

[0024] Gravity anchorage;

[0025] At least one jacking device is located between the end of the gravity anchor near the bridge tower and the bedrock.

[0026] Based on the above technology, the gravity anchor includes an anchor foundation, an anchor body, and a support pier. The anchor body and the support pier are located on top of the anchor foundation, and the anchor foundation, anchor body, and support pier form a triangle.

[0027] Based on the above technologies,

[0028] The jacking device is connected to the anchor foundation;

[0029] And / or the jacking device is connected to the support.

[0030] Based on the above technology, the gravity anchor is divided into a first region and a second region between the end near the bridge tower and the bedrock. The jacking device is set in the first region, and the second region is provided with a post-pouring strip.

[0031] Compared with the prior art, the advantages of the present invention are as follows:

[0032] This invention places the gravity anchor in bedrock with a good foundation, and sets up at least one jacking device between the end of the gravity anchor near the bridge tower and the bedrock. The jacking device pushes the gravity anchor with a force F. Since the component of F and f on a straight line is no greater than f, the gravity anchor does not shift. Compared with the existing construction of gravity anchors, this construction method, by setting up a jacking device between the gravity anchor and the bedrock, allows the gravity anchor to store frictional force in the direction of the main cable tension. When the main cable pulls the gravity anchor, the frictional force and the jacking force can jointly resist the horizontal tension of the main cable, thereby reducing the frictional force requirement of the gravity anchor, thus reducing the size of the anchor and reducing the amount of engineering work required for anchor construction. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the reverse pre-jacking anchorage according to an embodiment of the present invention;

[0034] Figure 2 for Figure 1 The front view;

[0035] In the figure: 1-bedrock, 2-gravity anchor, 21-anchor foundation, 22-anchor body, 23-support, 3-post-cast strip, 4-jacking device. Detailed Implementation

[0036] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0037] The construction method of the reverse pre-jacking anchorage in this embodiment of the invention is described in [reference needed]. Figure 1 As shown, the specific steps include:

[0038] S1: Place the gravity anchor 2 in the bedrock 1;

[0039] S2: At least one jacking device 4 is installed between the end of the gravity anchor 2 near the bridge tower and the bedrock 1;

[0040] S3: Calculate the frictional force f between the bottom of gravity anchor 2 and bedrock 1;

[0041] S4: The jacking device 4 jacks the gravity anchor 2 with a force of F, wherein the component of F in the direction opposite to f is not greater than f;

[0042] S5: Connect the main cable to gravity anchor 2.

[0043] Therefore, this invention places the gravity anchor 2 in bedrock 1 with a good foundation, and sets at least one jacking device 4 between the end of the gravity anchor 2 near the bridge tower and the bedrock 1. The jacking device 4 jacks the gravity anchor 2 with a force F. Since the component of F and f on a straight line is not greater than f, the gravity anchor 2 does not shift. Compared with the existing construction of gravity anchors, this construction method, by setting the jacking device 4 between the gravity anchor 2 and the bedrock 1, allows the gravity anchor 2 to store frictional force in the direction of the main cable tension. When the main cable pulls the gravity anchor 2, the frictional force and the jacking force can resist the horizontal tension of the main cable together, thereby reducing the frictional force requirement of the gravity anchor 2, thus reducing the size of the anchor and reducing the amount of work involved in the anchor construction.

[0044] It should be noted that the component of force F in the direction opposite to f is not greater than f because: when the direction of F is opposite to the direction of f, the entire force of F is used to counteract f; when the direction of F forms an obtuse angle with the direction of f, part of the force of F is used to counteract f, and this part is the component of F in the direction opposite to f. Therefore, when the component of F in the direction opposite to f is greater than f, the gravity anchor 2 will be displaced, thus changing the construction data. The data needs to be recalculated, increasing the workload. F can be read from the hydraulic pressure gauge connected to the jacking device, and f can be calculated from the friction coefficient between the gravity anchor 2 and the bedrock 1 and the weight of the gravity anchor 2.

[0045] An optimal combination of F and f is provided, where the horizontal component of the main cable is T, and F and T are in the opposite direction, F = T / 2, and f = T / 2.

[0046] It should be noted that the reverse counter-clinching allows the anchorage to store frictional force in the direction of the main cable tension. As construction progresses, the main cable tension gradually increases, and the base frictional force first decreases to 0, then increases in the opposite direction of the main cable tension until it balances the main cable tension along with the counter-clinching force. The base frictional force f = TF, where T is the horizontal component of the main cable force and F is the counter-clinching force. To ensure that the anchorage does not slip in either direction and to fully utilize the base frictional force, F can be at most equal to T / 2. At this point, f is at its minimum, also equal to T / 2.

[0047] Preferably, after S4 and before S5, the following steps are also included: dividing the space between the end of the gravity anchor 2 near the bridge tower and the bedrock 1 into a first region and a second region, the first region being used to place the jacking device 4; and pouring concrete in the second region to form a post-cast strip 3.

[0048] Furthermore, after the post-cast strip 3 is formed, the following steps are also included: removing the jacking device 4.

[0049] It should be noted that after the post-pouring strip 3 has solidified, its strength has been determined. Therefore, the post-pouring strip 3 can replace the jacking device 4 to apply jacking force to the gravity anchor 2. Thus, the jacking device 4 can be removed, saving construction costs.

[0050] Preferably, the jacking device 4 in S4 jacks the gravity anchor 2 with a force of F, specifically including the following steps: the jacking force of the jacking device 4 on the gravity anchor 2 gradually increases from 0 until the jacking force reaches F, and the direction of the jacking force is the same as the opposite direction of the horizontal tension of the main cable, or the direction of the jacking force forms an acute angle with the opposite direction.

[0051] When the direction of the jacking force is the same as the opposite direction of the horizontal tension of the main cable, T = F + f;

[0052] When the direction of the jacking force forms an acute angle with the opposite direction of the horizontal tension of the main cable, the component of F in the direction of the horizontal tension of the main cable can be calculated first by using F and the deviation angle, and then the value of F can be designed.

[0053] Preferably, S2 specifically includes the following steps:

[0054] By calculation, several jacking points are set at the end of the anchor foundation 21 of the gravity anchor 2 near the bridge tower, and several jacking devices 4 are installed on the bedrock 1, with the number of jacking devices 4 matching the number of jacking points.

[0055] The design location of the jacking device 4 can be as follows:

[0056] At least one jacking device 4 is installed between the anchor foundation 21 of the gravity anchor 2 and the bedrock 1 at the end near the bridge tower.

[0057] And / or, at least one jacking device 4 is provided between the end of the pier 23 of the gravity anchor 2 near the bridge tower and the bedrock 1;

[0058] And / or, the jacking device 4 can also be connected to other components of the gravity anchor 2.

[0059] It should be noted that the specific design location of the jacking device 4 can be determined according to construction needs and the construction site.

[0060] Preferably, before S1, the following steps are also included: digging a pit in the bedrock 1 at the preset position of the gravity anchor 2, the width of the pit being greater than the width of the gravity anchor 2, so that there is space between the gravity anchor 2 and the bedrock 1 for setting up the jacking device 4.

[0061] The reverse pre-topped anchorage in this embodiment of the invention, see [link / reference]. Figure 1 As shown, it includes a gravity anchor 2, and at least one jacking device 4 is provided between the end of the gravity anchor 2 near the bridge tower and the bedrock 1. The number of jacking devices 4 is designed according to the construction needs.

[0062] Further, see Figure 2 As shown, the gravity anchor 2 includes an anchor foundation 21, an anchor body 22, and a support 23. The anchor body 22 and the support 23 are located on top of the anchor foundation 21, and the anchor foundation 21, the anchor body 22, and the support 23 form a triangle.

[0063] Furthermore, a specific design location for the jacking device 4 is provided:

[0064] The jacking device 4 is connected to the anchor foundation 21;

[0065] And / or the jacking device 4 is connected to the support 23.

[0066] Preferably, the gravity anchor 2 is divided into a first region and a second region between the end near the bridge tower and the bedrock 1. The jacking device 4 is set in the first region, and the second region is provided with a post-cast strip 3.

[0067] The benefits of this design are:

[0068] After the post-cast strip 3 solidifies, its strength is fixed, so the post-cast strip 3 can replace the jacking device 4 to apply jacking force to the gravity anchor 2. Therefore, the jacking device 4 can be removed, saving construction costs.

[0069] This invention is not limited to the preferred embodiments described above. Anyone inspired by this invention can derive other forms of products. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this invention is within its protection scope.

Claims

1. A construction method for a reverse pre-jacking type anchorage, characterized in that, This method is applied to a reverse pre-jacking anchorage, which includes: a gravity anchorage (2); at least one jacking device (4) disposed between the end of the gravity anchorage (2) near the bridge tower and the bedrock (1); the gravity anchorage (2) includes an anchorage foundation (21), an anchor body (22) and a support (23), the anchor body (22) and the support (23) being disposed on top of the anchorage foundation (21), and the anchorage foundation (21), the anchor body (22) and the support (23) forming a triangle; The method includes the following steps: The gravity anchor (2) is placed in the bedrock (1); At least one jacking device (4) is installed between the end of the gravity anchor (2) near the bridge tower and the bedrock (1). Calculate the frictional force f between the bottom of the gravity anchor (2) and the bedrock (1); The jacking device (4) jacks the gravity anchor (2) with a force of F. The jacking force of the jacking device (4) on the gravity anchor (2) gradually increases from 0 until it reaches F. The direction of the jacking force is the same as the opposite direction of the horizontal tension of the main cable, or the direction of the jacking force is at an acute angle to the opposite direction. The component of F in the direction opposite to f is not greater than f. In addition, F can be read by the oil pressure gauge connected to the jacking device (4), and f can be calculated by the friction coefficient between the gravity anchor (2) and the bedrock (1) and the weight of the gravity anchor (2). The space between the end of the gravity anchor (2) near the bridge tower and the bedrock (1) is divided into a first area and a second area. The first area is used to place the jacking device (4); concrete is poured in the second area to form a post-cast strip (3). Connect the main cable to the gravity anchor (2) and remove the jacking device (4).

2. The construction method of the reverse pre-jacking anchorage as described in claim 1, characterized in that, At least one jacking device (4) is installed between the end of the gravity anchor (2) near the bridge tower and the bedrock (1), specifically including the following steps: By calculation, several jacking points are set at the end of the anchor foundation (21) of the gravity anchor (2) near the bridge tower, and several jacking devices (4) are installed on the bedrock (1), and the number of jacking devices (4) matches the number of jacking points.

3. The construction method of the reverse pre-jacking anchorage as described in claim 1, characterized in that, Before placing the gravity anchor (2) in the bedrock (1), the following steps are also included: A pit is dug in the bedrock (1) at the preset position of the gravity anchor (2). The longitudinal bridge length of the pit is greater than the longitudinal bridge length of the gravity anchor (2), so that there is space between the gravity anchor (2) and the bedrock (1) to install the jacking device (4).

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