A gravity anchorage construction method for suspension bridge

Abstract

The present invention provides a method for constructing a gravity anchorage for a suspension bridge, relating to the technical field of bridge construction. The method comprises the following steps: S1: excavating an anchorage pit and dividing the pit into multiple small sections; S2: excavating a first construction platform on one side of the anchorage pit; S3: positioning construction equipment on a small section near the first construction platform and constructing corresponding anchorage blocks on multiple small sections away from the first construction platform; S4: positioning construction equipment on the first construction platform and constructing the last anchorage block on a small section near the first construction platform. With this method, the construction of each anchorage block in each small section of the anchorage pit is asynchronous, and the small section near the first construction platform serves as a temporary construction platform while the other sections are being constructed, thus avoiding the need to excavate construction platforms on all sides.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge construction, and in particular to a method for constructing a gravity anchorage of a suspension bridge. Background Art

[0002] Anchors are a core component of suspension bridges. One end of the main cable is stabilized on the anchor, and the tension on the anchor is transmitted to the foundation through the anchor. Anchors are typically large concrete blocks cast underground, or anchored into the mountain. Traditional anchor construction methods involve casting each anchor block vertically and evenly within the anchor pit. Circular construction platforms are required around the anchors, resulting in significant excavation and backfilling, a significant environmental impact, and slow construction progress. Summary of the Invention

[0003] The present invention aims to propose a method for constructing a gravity anchorage for a suspension bridge, so as to solve the technical problem of a long construction period of the existing anchorage.

[0004] To achieve the above object, the technical solution of the present invention is as follows:

[0005] A method for constructing a gravity anchorage for a suspension bridge, wherein the anchorage comprises a plurality of anchorage blocks, comprises the following steps:

[0006] S1: excavating an anchor pit and dividing the anchor pit into multiple small sections;

[0007] S2: excavating a first construction platform on one side of the anchor pit;

[0008] S3: The construction equipment is positioned in one of the small intervals close to the first construction work platform, and constructs the corresponding anchor blocks in multiple small intervals away from the first construction work platform;

[0009] S4: The construction equipment is positioned on the first construction platform, and constructs the last anchor block on one of the small intervals close to the first construction platform.

[0010] In the gravity anchorage construction method for a suspension bridge described in the present invention, the anchorage foundation pit is divided into multiple small intervals, the anchorage can be divided into multiple anchorage blocks, the anchorage blocks on each small interval are constructed asynchronously, a small interval close to the first construction work platform in the anchorage foundation pit is reserved for the last pouring, when pouring multiple small intervals away from the first construction work platform, the construction equipment can be positioned on a small interval close to the first construction work platform, and the small interval is used as a temporary construction work platform. When the other small intervals except the last one are poured, the anchorage blocks are constructed asynchronously. After all the other small intervals are poured, the construction equipment moves to the first construction work platform to transport concrete and overhead pumps to complete the construction of the last anchor block. The previously poured anchor blocks and the last poured anchor blocks together constitute a complete anchor, realizing the entire anchor construction under the condition of local excavation. The suspension bridge gravity anchor construction method described in the present invention does not need to set up construction work platforms around the anchor foundation pit, reducing the workload of earth excavation and backfilling, and has higher construction efficiency and more secure construction progress.

[0011] Optionally, in S1, the process of excavating the anchor pit includes: at the location of the anchor pit to be excavated, excavating in steps by sloping the ground from the back of the mountain to the side facing the mountain.

[0012] Optionally, in S1, after the excavation of the anchor pit, an in-situ test of the rock foundation is performed on the base of the anchor pit, and the bearing capacity and friction coefficient of the base obtained by the test are compared with a first preset value. When it is detected that the bearing capacity and friction coefficient of the base are less than the first preset value, the base is processed until the first preset value is reached.

[0013] Optionally, the first preset value is a design value taken by the survey and design institute when designing the bridge based on the bearing capacity of the base and soil parameters in the geological survey report.

[0014] Optionally, in S1, the anchor pit is divided into four small intervals, the four small intervals are arranged opposite to each other in pairs, and the number of the anchor blocks is consistent with the number of the small intervals.

[0015] Optionally, in S2, the process of excavating the first construction work platform on one side of the anchor pit includes: comparing the bearing capacity of the base of each of the small rooms on the back side of the mountain, and excavating the first construction work platform on one side of the small room with the worst bearing capacity.

[0016] Optionally, in S3, when constructing the corresponding anchor blocks on the plurality of small intervals away from the first construction work platform, each anchor block is constructed evenly and synchronously upward.

[0017] Optionally, before S4, the method further includes: regularly detecting the settlement of the bases between all the small blocks until the settlement difference between the bases with the anchor blocks constructed and the bases without the anchor blocks constructed reaches a second preset value.

[0018] Optionally, the design process of the second preset value includes: calculating the settlement of the base according to the soil parameters of the base of the anchor pit, analyzing the calculated settlement of the base of the last small area to be constructed when the construction between the small areas is asynchronous, and determining the second preset value based on the calculated settlement of the last small area and the observed settlements of the other small areas.

[0019] Optionally, the suspension bridge gravity anchorage construction method further includes S5, backfilling around the anchorage to form a second construction work platform, and the construction equipment is positioned on the second construction work platform to construct a post-cast strip. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Flowchart of a method for constructing a suspension bridge gravity anchorage according to an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the structure corresponding to S2 in the gravity anchorage construction method for a suspension bridge according to an embodiment of the present invention;

[0022] Figure 3 Schematic diagram of the structure corresponding to S3 in the gravity anchorage construction method for a suspension bridge according to an embodiment of the present invention;

[0023] Figure 4 for Figure 3 Structural diagram from another perspective;

[0024] Figure 5 Schematic diagram of the structure of the anchor according to an embodiment of the present invention;

[0025] Figure 6 Schematic diagram of the structure corresponding to S4 in the gravity anchorage construction method for a suspension bridge according to an embodiment of the present invention;

[0026] Figure 7 Schematic diagram of the structure corresponding to S5 in the gravity anchorage construction method for a suspension bridge according to an embodiment of the present invention.

[0027] Description of reference numerals:

[0028] 1. Anchor pit; 11. Small interval; 111. First interval; 112. Second interval; 113. Third interval; 114. Fourth interval; 2. First construction platform; 3. Second construction platform; 4. Post-cast strip; 5. Anchor; 51. Anchor block; 52. Anchor block; 53. Loose-cable pier foundation; 54. Loose-cable pier; 55. Front anchor chamber; 6. Construction equipment; 7. Back side of the mountain; 8. Side facing the mountain. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "matched" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0031] In addition, it should be noted that in the description of the present invention, it should be noted that the terminology nouns in each embodiment, such as "upper", "lower", "front", "back" and other words indicating direction, are only for simplifying the description of the positional relationship based on the drawings in the specification, and do not mean that the referred elements and devices must be operated in accordance with the specific directions and defined operations and methods and structures in the specification. Such direction nouns do not constitute a limitation on the present invention.

[0032] A coordinate system XYZ is set in this article, wherein the positive direction of the X axis represents the front, the negative direction of the X axis represents the back, the positive direction of the Y axis represents the left direction, the negative direction of the Y axis represents the right direction, the positive direction of the Z axis represents the upper direction, and the negative direction of the Z axis represents the lower direction.

[0033] Figure 2-3 The arrows shown in 6-7 indicate the directions of the mountain side and the back mountain side.

[0034] like Figure 1 As shown, a method for constructing a gravity anchorage for a suspension bridge according to an embodiment of the present invention, wherein the anchorage 5 includes a plurality of anchorage blocks 51, comprises the following steps:

[0035] like Figure 2 As shown, S1: excavating an anchor pit 1 and dividing the anchor pit 1 into a plurality of small intervals 11.

[0036] In this step, the anchor pit 1 can be set under the upper foot for constructing the anchor 5, such as Figure 5As shown, the anchor 5 serves as the tension-bearing end of the main cable of the bridge. The size of the anchor pit 1 is much larger than the size of the anchor 5. Taking the anchor construction of the Dali bank of the Taoyuan Jinsha River Bridge as an example, the cross-sectional size of the anchor pit 1 can be 134.97m×85.95m, with a depth of 12~22m, and the size of the anchor 5 is 51m×51m×37.5m. It can be seen that the anchor size of the gravity anchor is large, and the amount of earth excavated in the anchor pit 1 is large. The amount of earth excavation seriously affects the construction progress and project period.

[0037] The anchor pit 1 is divided into a plurality of small intervals 11, and the anchor blocks 51 are constructed in the corresponding small intervals. The anchor blocks 51 of each small interval 11 are assembled into the anchor 5, which is divided into parts and is more convenient and flexible to construct.

[0038] It should be noted that if Figure 4 As shown, along the vertical direction of the anchor 5, the anchor is composed of an anchor block 52, a loose cable sleeve pier foundation 53, a loose cable sleeve pier 54 and a front anchor chamber 55 connected in sequence; Figure 3 As shown, the anchor 5 is divided into a plurality of anchor blocks 51. The sizes, weights and shapes of the anchor blocks 51 are different. At the corresponding positions between the small blocks, whether it is the anchor block 52, the loose-cable pier foundation 53 or the loose-cable pier 54, they are all constructed layer by layer with a distance of about 2 meters. There is no absolute construction gap between the anchor block 52, the loose-cable pier foundation 53 and the loose-cable pier 54.

[0039] like Figure 2 As shown, optionally, in said S1, the process of excavating the anchor pit 1 includes: at the location of the anchor pit to be excavated, excavating in steps by successively sloping from the back-mountain side 7 to the side facing the mountain 8.

[0040] In this embodiment, when excavating the anchor pit 1, a combination of mechanical excavation and blasting excavation can be adopted; the slope gradient of the graded excavation is 1:0.75, and the height of each step can be designed according to the geological conditions. Generally, it can be set to 10m. The sides of the anchor pit 1 can adopt different inclination angles to adapt to the different terrain and geological conditions around the anchor; during the excavation process, slope protection must also be done to avoid damage to the slope or soil and rocks sliding into the anchor pit 1, affecting the construction of the anchor.

[0041] Here, because the anchor foundation pit 1 is relatively large, it is usually excavated step by step from the back mountain side 7 to the mountain side 8, and excavated from top to bottom. Usually, the back mountain side has been excavated to the base, and there is still a lot on the mountain side that has not been excavated to the base.

[0042] Optionally, in S1, after the excavation of the anchor pit 1, an in-situ test of the rock foundation of the base of the anchor pit 1 is carried out, and the bearing capacity and friction coefficient of the base obtained by the test are compared with a first preset value. When it is detected that the bearing capacity and friction coefficient of the base are less than the first preset value, the base is processed until the first preset value is reached.

[0043] In this embodiment, after excavating the anchor pit 1 and before pouring the anchor 5, the various parameter indicators of the base in the anchor pit 1 are tested once a week to ensure that the base has good bearing capacity, so that after the construction of each anchor block 51 is completed, the base has a relatively small settlement difference, providing a basis for the asynchronous construction of the anchor blocks.

[0044] Generally, when analyzing the bearing performance and friction characteristics of the anchor base based on in-situ tests of the anchor base rock foundation, it is required that the bearing capacity and base friction coefficient of the tested base are not less than the bearing capacity and base friction coefficient of the survey and design (that is, the first preset value), which can ensure that after the anchor blocks are cast, the relative settlement caused between the blocks is small.

[0045] For example, taking the anchor construction of the Taoyuan Jinsha River Bridge as an example, the anchors at both ends of the bridge are the Yongsheng shore anchor and the Dali shore anchor. After in-situ rock foundation test results, the bearing capacity of the Dali shore anchor base is greater than 1000kPa, which is far greater than the survey and design value of 450kPa. The geology of the site is good.

[0046] Optionally, the first preset value is a design value taken by the survey and design institute when designing the bridge based on the bearing capacity and soil parameters of the base in the geological survey report.

[0047] In this embodiment, the geological survey report is issued by the geological survey and design institute. Due to the large size of the gravity anchor, it is impossible to survey the stratum parameters at each location during the geological survey and design. Often, a survey point is taken at intervals of 10 to 30 meters. This will result in many anchor foundation pits being excavated during construction. The bearing capacity of the foundation will deviate significantly from the value taken during the survey and design, requiring re-testing and correction. However, it should not be ignored that the survey and design values ​​can be used as a reference standard to compare the bearing capacity of the base detected during the actual excavation process with the survey and design values.

[0048] Optionally, in S1 , the anchor pit 1 is divided into four small intervals 11 , the four small intervals 11 are arranged opposite to each other in pairs, and the number of the anchor blocks 51 is the same as the number of the small intervals 11 .

[0049] In this embodiment, the four sub-areas 11 may include a first area 111, a second area 112, a third area 113, and a fourth area 114. The first area 111 and the third area 113 are located on the mountain side 8, and the second area 112 and the fourth area 114 are located on the mountain side 7. Casting the corresponding four anchor blocks 51 in each of the four sub-areas 11 facilitates construction.

[0050] like Figure 2 As shown, S2: excavating a first construction platform 2 on one side of the anchor pit 1.

[0051] In this step, the first construction platform 2 is used to transport materials such as concrete pumps, concrete trucks, and steel formwork required for concrete pouring, and is used when pouring the four small sections 11. Based on the fourth section 114 being used as a temporary construction platform, the first construction platform 2 only needs to be set up on one side of the anchor pit 1, without the need for access roads on all sides. This greatly reduces the workload of earth excavation and backfilling, facilitates construction and earth transportation, reduces construction costs, has little impact on the environment, and shortens the construction period.

[0052] Optionally, in S2, the process of excavating the first construction work platform 2 on one side of the anchor pit 1 includes: comparing the bearing capacity of the base of each of the small intervals 11 on the back side of the mountain, and excavating the first construction work platform 2 on one side of the small interval 11 with the worst bearing capacity.

[0053] In this embodiment, taking into account the convenience of construction and the workload of earth excavation and backfilling, the first construction work platform 2 is generally set up on the back side of the mountain, and one of the second intervals 112 and the fourth interval 114 with the worst base bearing capacity is selected for delayed construction, temporarily serving as a temporary construction work platform for the construction of the other three small intervals 11. For example, the first construction work platform 2 is set up on the back side of the mountain of the fourth interval 114, and the fourth interval 114 is selected as the temporary construction work platform for the construction of the other three small intervals 11. The interval division method is reasonable and the construction is convenient.

[0054] like Figure 3-4 As shown, S3: the construction equipment is positioned on one of the small intervals 11 close to the first construction work platform 2 , and the corresponding anchor blocks 51 are constructed on multiple small intervals 11 away from the first construction work platform 2 .

[0055] In this step, the first section 111, the second section 112 and the third section 113 on the mountain side are constructed first. When constructing the anchor blocks 51 on the first section 111, the second section 112 and the third section 113, the construction equipment and some building materials can be placed on the fourth section 114, so as to rationally utilize the space and reduce the excavation workload of the construction platform around the first section 111, the second section 112 and the third section 113.

[0056] Here, steel bar processing and installation, mass concrete pouring and formwork construction can follow conventional construction methods.

[0057] Optionally, in S3, when constructing the corresponding anchor blocks 51 on the plurality of small intervals 11 on the side away from the first construction work platform 2, each anchor block 51 is constructed evenly and synchronously upward.

[0058] In this embodiment, when pouring the anchor blocks 51 in the first, second, and third sections 111, 112, and 113, the three anchor blocks 51 are constructed evenly and simultaneously upward, minimizing the impact of uneven settlement of the anchor base. During construction, each section is constructed upwards, layer by layer, at a depth of 2 meters.

[0059] like Figure 6 As shown, S4: the construction equipment is positioned on the first construction work platform 2 and constructs the last anchor block 51 on one of the small intervals 11 close to one side of the first construction work platform 2 .

[0060] In this step, when pouring the fourth section 114, construction equipment and some building materials can be placed on the first construction platform 2, and each anchor block 51 is constructed asynchronously to minimize the number of construction platforms, reduce environmental impact, and reduce construction costs.

[0061] Optionally, before S4, the method further includes: regularly detecting the settlement of the bases of all the small intervals 11 until the settlement difference between the base with the anchor blocks 51 cast and the base without the anchor blocks 51 cast reaches a second preset value.

[0062] In this embodiment, during the construction of the anchor blocks 51, basement settlement observation points are located outside each anchor block 51, and basement settlement observations are conducted every two days. Generally, when the basement settlement difference of the anchor blocks 51 already cast exceeds 2 cm, it is necessary to cast the anchor blocks 51 in the fourth section 114.

[0063] Optionally, the design process of the second preset value includes: calculating the settlement of the base according to the soil parameters of the base of the anchor pit 1, and analyzing the calculated settlement of the base of the last small interval 11 to be completed when the small intervals 11 are not cast synchronously. In this project, the calculated settlement of the small interval 11 is 5mm. After the construction of the cast small intervals in this project is completed, the maximum observed settlement difference is 5mm. The value obtained by subtracting the calculated settlement of the last small interval 11 from the observed settlement of each of the other small intervals 11 and adding 2cm is used as the second preset value. In this embodiment, if the bearing capacity of the base of the anchor pit 1 is less than the first preset value, that is, less than the survey and design value, the base needs to be processed so that the bearing capacity of the base and the friction coefficient of the base are not less than the designed values, which can ensure that the relative settlement is small when the blocks are constructed asynchronously. Figure 7 As shown, optionally, the suspension bridge gravity anchorage construction method further includes S5, backfilling around the anchorage 5 to form a second construction work platform 3, and the construction equipment 6 stands on the second construction work platform 3 to construct the post-cast strip 4.

[0064] In this embodiment, since the bottom of the first interval 111, the second interval 112 and the third interval 113 have been completed, backfill can be carried out around them to form a second construction work platform 3, which can meet the later construction of the anchor blocks 51 on the first interval 111, the second interval 112 and the third interval 113, as well as the construction of the post-cast strip 4.

[0065] Cast the post-cast strip 4 between each anchor block 51, such as Figure 7 As shown, the post-cast strip 4 can be cross-shaped. The cross-shaped post-cast strip 4 divides the anchor foundation pit 1 into four small intervals 11. The cross-shaped post-cast strip 4 is first constructed along the length direction of the bridge and then along the width direction of the bridge. The post-cast strip 4 is constructed after the anchor block 51 is cast, and is used for the internal shrinkage of the anchor 5 to avoid cracks caused by its own shrinkage or uneven settlement.

[0066] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for constructing a gravity anchorage for a suspension bridge, characterized in that: The anchor (5) comprises a plurality of anchor blocks (51), and includes the following steps: S1: excavating an anchor foundation pit (1), and dividing the anchor foundation pit (1) into a plurality of small sections (11); S2: excavating a first construction platform (2) on one side of the anchor pit (1); S3: The construction equipment (6) is positioned on one of the small intervals (11) close to the first construction work platform (2), and constructs the corresponding anchor blocks (51) on a plurality of the small intervals (11) away from the first construction work platform (2); S4: The construction equipment (6) is positioned on the first construction platform (2) and constructs the last anchor block (51) on one of the small intervals (11) close to the first construction platform (2).

2. The method for constructing a suspension bridge gravity anchorage according to claim 1, characterized in that: In said S1, the process of excavating the anchor foundation pit (1) includes: at the location of the anchor foundation pit to be excavated, excavating in steps in a direction from the back of the mountain (7) to the side facing the mountain (8) in sequence.

3. The method for constructing a suspension bridge gravity anchorage according to claim 2, characterized in that: In said S1, after excavating the anchor pit (1), an in-situ test of the rock foundation of the base of said anchor pit (1) is carried out, and the bearing capacity and friction coefficient of said base obtained by the test are compared with a first preset value. When it is detected that the bearing capacity and friction coefficient of said base are less than the first preset value, said base is processed until it reaches the first preset value.

4. The method for constructing a suspension bridge gravity anchorage according to claim 3, characterized in that: The first preset value is a design value taken by the survey and design institute when designing the bridge based on the bearing capacity of the base and soil parameters in the geological survey report.

5. The method for constructing a suspension bridge gravity anchorage according to claim 1, wherein: In S1, the anchor pit (1) is divided into four small intervals (11), the four small intervals (11) are arranged opposite to each other in pairs, and the number of the anchor blocks (51) is consistent with the number of the small intervals (11).

6. The method for constructing a suspension bridge gravity anchorage according to claim 3, characterized in that: In S2, the process of excavating the first construction work platform (2) on one side of the anchor foundation pit (1) includes: comparing the bearing capacity of the base of each of the small intervals (11) on the back side of the mountain, and excavating the first construction work platform (2) on the side of the small interval (11) with the worst bearing capacity.

7. The method for constructing a suspension bridge gravity anchorage according to claim 1, wherein: In said S3, when constructing the corresponding said anchor blocks (51) on the side of the plurality of said small intervals (11) away from the first construction work platform (2), each said anchor block (51) is constructed upwardly uniformly and synchronously.

8. The method for constructing a suspension bridge gravity anchorage according to claim 1, wherein: Before S4, the method further includes: regularly detecting the settlement of the bases of all the small intervals (11) until the settlement difference between the bases where the anchor blocks (51) have been constructed and the bases where the anchor blocks (51) have not been constructed reaches a second preset value.

9. The method for constructing a suspension bridge gravity anchorage according to claim 8, characterized in that: The design process of the second preset value includes: calculating the settlement of the base according to the soil parameters of the base of the anchor foundation pit (1), analyzing the calculated settlement of the base of the last small interval (11) completed when the small intervals (11) are not constructed synchronously, and determining the second preset value according to the calculated settlement of the last small interval (11) and the observed settlement of the other small intervals (11).

10. The method for constructing a suspension bridge gravity anchorage according to claim 1, wherein: It also includes S5, backfilling around the anchor (5) to form a second construction work platform (3), and the construction equipment (6) is positioned on the second construction work platform (3) to construct the post-casting strip (4).

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