Construction method of bridge abutment in cliff section tunnel

Abstract

The application discloses a kind of cliff section hole inside bridge abutment construction methods, it is related to cliff section hole inside bridge abutment construction field, the cliff section includes upper slope and lower slope, the method includes: using rigid frame bridge in the cliff section hole inside construction formation upper structure;Using equal-section double-limb thin-walled pier, pile foundation in the cliff section hole inside construction formation lower structure by pile cap;Using prestressed concrete T beam, first simply supported then structure continuous formation approach bridge upper structure;Using the mode of no pile foundation, in the lower structure do abutment cap, form the cliff section hole inside bridge abutment of the application.By respectively in the cliff section hole inside construction formation upper structure and lower structure, and using the mode of no pile foundation, form the cliff section hole inside bridge abutment of the application, simplify construction step, reduce the construction difficulty of cliff section hole inside bridge abutment, thereby reduce construction risk, while ensuring construction quality, shorten construction period long, reduce engineering cost high.

Description

Technical Field

[0001] This invention relates to the field of bridge abutment construction technology in steep cliff sections, and particularly to a method for constructing bridge abutments inside tunnels in steep cliff sections. Background Technology

[0002] Most bridge sites are located in tectonic-karst low-mountain canyon landforms. For example, the river near the bridge site has a direction of approximately 192°, a riverbed width of 112-118m, and a longitudinal slope of about 0.3%, making it a perennial river. On the right bank of the river, the slope of the bridge site area has a direction of approximately 180°, with a ground elevation of 287-469m and a relative elevation difference of about 182m. The bridge abutment is located on steep cliffs with steep slopes of 70-85°, some areas being vertical, and the slope surface is uneven. The slope angle at the lower part of the cliff is generally 25-40°, and can reach 50° in some areas. On the left bank, the terrain is more undulating, forming a "two valleys and three mountains" topography, with a ground elevation of 287-378m and a relative elevation difference of about 91m. The slope angle is generally 15-45°, and can reach 70-80° in some areas.

[0003] In related technologies, conventional bridge-tunnel connection designs in mountainous areas mainly involve connecting the bridge abutment tail to the tunnel portal, resulting in minimal mutual interference during construction. However, this ideal bridge-tunnel connection method cannot be realized in actual engineering projects when limited by steep slope terrain. In rugged mountain areas, the bridge abutment often extends directly into the tunnel portal. Constructing the bridge abutment using conventional construction methods would damage the original landform of the tunnel portal, specifically manifested as deep foundation pits, sloping excavation, large excavation and backfill volumes, large and difficult protection requirements, easy instability of excavated slopes, high construction risks, long construction period, and high project costs.

[0004] Therefore, there is an urgent need for a construction method for bridge abutments inside tunnels in steep cliff sections, which simplifies the construction steps and reduces the difficulty of constructing bridge abutments inside tunnels in tectonic karst canyon landforms in low and medium mountain areas. Summary of the Invention

[0005] The main objective of this invention is to provide a construction method for a large bridge abutment inside a tunnel in a steep cliff section. This method aims to solve the technical problem of the urgent need for a construction method for a large bridge abutment inside a tunnel in a steep cliff section in the existing technology, simplify the construction steps of the large bridge abutment inside a tunnel in a steep cliff section, and reduce the technical difficulty of constructing a large bridge abutment inside a tunnel in a low mountain canyon landform with tectonic karst topography.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a method for constructing a bridge abutment inside a tunnel in a steep cliff section, wherein the steep cliff section includes an upper slope and a lower slope, characterized in that the method includes:

[0008] A rigid frame bridge was constructed inside the tunnel in the steep cliff section to form the superstructure.

[0009] A double-limb thin-walled pier with equal cross-section is used, and the pile foundation is constructed inside the tunnel in the steep cliff section to form the substructure.

[0010] The approach bridge superstructure is formed by using prestressed concrete T-beams, initially simply supported and then structurally continuous.

[0011] Using a pileless foundation method, a cap is constructed on the substructure to form the bridge abutment inside the tunnel in the steep cliff section.

[0012] Optionally, in the above-mentioned construction method for the bridge abutment inside the tunnel in the steep cliff section, the superstructure includes a three-span prestressed concrete variable cross-section continuous box girder, and the continuous box girder is a single-span single-box single-cell cross-section structure.

[0013] Optionally, in the above-mentioned construction method for the bridge abutment inside the tunnel in the steep cliff section, the top width of the continuous box girder is 12.25m, the bottom plate width is 6.75m, and the length of the cantilever on both sides is 2.75m.

[0014] Optionally, in the above-mentioned construction method for the bridge abutment inside the tunnel in the steep cliff section, the mid-span height of the continuous box girder is 3.5m, the height of the center beam of the box girder at the support is 9.5m, and the beam height changes in a parabolic pattern from 4.0m away from the center of the main pier to 70.0m in the mid-span direction.

[0015] Optionally, in the above-mentioned construction method for the bridge abutment inside the tunnel in the steep cliff section, the continuous box girder is provided with two first diaphragms at the thin-walled position of the pier corresponding to the middle pier.

[0016] Optionally, in the above-mentioned construction method for the bridge abutment inside the tunnel in steep cliff sections, the thickness of the first diaphragm is 2.0m.

[0017] Optionally, in the above-mentioned construction method for the bridge abutment inside the tunnel in steep cliff sections, a second diaphragm is provided in the middle of the middle span of the continuous box girder.

[0018] Optionally, in the above-mentioned construction method for the bridge abutment inside the tunnel in steep cliff sections, the thickness of the second diaphragm is 0.5m.

[0019] Optionally, in the above-mentioned construction method for the bridge abutment inside the tunnel in steep cliff sections, a transverse diaphragm with a thickness of 2.0m is provided at the end of the side span of the continuous box girder.

[0020] Optionally, in the above-mentioned construction method for the bridge abutment inside the tunnel in steep cliff sections, the elevation difference between the upper slope and the lower slope is at least 182m.

[0021] The above-described one or more technical solutions provided by this invention can have the following advantages or at least achieve the following technical effects:

[0022] This invention proposes a construction method for a bridge abutment inside a tunnel in a steep cliff section. By constructing an upper structure and a lower structure separately inside the tunnel in the steep cliff section, and using a pileless foundation method, a cap is made on the lower structure to form the bridge abutment inside the tunnel in the steep cliff section. This simplifies the construction steps of the bridge abutment inside the tunnel in the steep cliff section, reduces the construction difficulty of the bridge abutment inside the tunnel in the tectonic karst low mountain canyon landform, thereby reducing construction risks, ensuring construction quality, shortening the construction period, and reducing the high project cost. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the construction method for the bridge abutment inside the tunnel in a steep cliff section according to the present invention.

[0025] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] It should be noted that in the embodiments of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0028] In this invention, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element. Furthermore, the meaning of "and / or" throughout the text includes three parallel options; for example, "A and / or B" includes option A, option B, or options where both A and B are satisfied.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "connection" and "fixed" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements.

[0030] In this invention, if there are descriptions involving "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0031] In this invention, the use of suffixes such as "module," "component," "part," "unit," or "unit" to denote elements is solely for the purpose of illustrative purposes and has no specific meaning in itself. Therefore, "module," "part," or "unit" can be used interchangeably.

[0032] For those skilled in the art, the specific meanings of the above terms in this invention can be understood according to the specific circumstances. Furthermore, the technical solutions of the various embodiments can be combined with each other; however, this is based on the premise that those skilled in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0033] The inventive concept of the present invention will be further explained below with reference to some specific embodiments.

[0034] This invention proposes a method for constructing bridge abutments inside tunnels in steep cliff sections.

[0035] Reference Figure 1 , Figure 1This is a schematic diagram of the construction method for the bridge abutment inside the tunnel in a steep cliff section according to the present invention.

[0036] In one embodiment of the present invention, such as Figure 1 As shown, a method for constructing a bridge abutment inside a tunnel in a steep cliff section, wherein the steep cliff section includes an upper slope and a lower slope, the method comprising:

[0037] Step S10: Construct the superstructure using a rigid frame bridge inside the tunnel in the steep cliff section;

[0038] Step S20: Using a double-limb thin-walled pier with equal cross-section, the pile cap and pile foundation are constructed inside the tunnel in the steep cliff section to form the substructure;

[0039] Step S30: Using prestressed concrete T-beams, the approach bridge superstructure is formed by first simply supporting and then making the structure continuous.

[0040] Step S40: Using a pileless foundation method, a cap is made on the lower structure to form the bridge abutment inside the tunnel in the steep cliff section.

[0041] For ease of understanding, a specific implementation method is shown below:

[0042] The slope of a certain bridge site has an angle of about 180°, with a ground elevation of 287-469m and a relative height difference of about 182m. The bridge abutment is a steep cliff with a slope angle of 70-85°, and in some places it is vertical. The slope surface is uneven. The slope angle of the lower part of the cliff is generally 25-40°, and can reach 50° in some places.

[0043] The main bridge (80+150+80)m superstructure adopts a rigid frame bridge, and the substructure adopts equal-section double-limb thin-walled piers with pile foundations. The approach bridge superstructure adopts prestressed concrete (post-tensioned) T-beams, initially simply supported and then structurally continuous. The substructure of abutment 0 enters the tunnel, with abutment caps and no pile foundations. Abutment 8 adopts a pile-column abutment, and piers 3 to 7 adopt column piers. The piers and abutments adopt bored pile foundations, and the pile foundations are friction piles.

[0044] It should be noted that the concrete strength grades of the main structure are as follows:

[0045] (1) Main beam of rigid frame bridge: C55

[0046] (2) Double-limb thin-walled pier: C40

[0047] (3) Foundation: C35

[0048] (4) Pile foundation: C30

[0049] The bridge has a total of 24 piers, including 20 cylindrical piers and 4 double-limb thin-walled piers, with the largest pier height being 65.675m.

[0050] The technical solution of this invention constructs an upper and lower structure separately inside the cave in a steep cliff section, and uses a pileless foundation method to build a cap on the lower structure to form a large bridge abutment inside the cave in the steep cliff section. This simplifies the construction steps of the large bridge abutment inside the cave in the steep cliff section, reduces the construction difficulty of the large bridge abutment inside the cave in the steep cliff section of the low mountain canyon landform of tectonic karst, thereby reducing construction risks, ensuring construction quality, shortening the construction period, and reducing the high project cost.

[0051] Furthermore, the superstructure includes a three-span prestressed concrete variable cross-section continuous box girder, wherein the continuous box girder is a single-span, single-box, single-cell cross-section structure.

[0052] Furthermore, the continuous box girder has a top width of 12.25m, a bottom plate width of 6.75m, and cantilever lengths of 2.75m on both sides.

[0053] Furthermore, the mid-span height of the continuous box girder is 3.5m, the height of the center beam of the box girder at the support is 9.5m, and the beam height varies in a parabolic pattern from 4.0m from the center of the main pier to 70.0m in the mid-span direction.

[0054] Furthermore, the continuous box girder has two first diaphragms at the thin-walled position of the pier corresponding to the middle pier.

[0055] Furthermore, the thickness of the first partition plate is 2.0m.

[0056] Furthermore, a second diaphragm is provided at the mid-span of the continuous box girder.

[0057] Furthermore, the thickness of the second partition is 0.5m.

[0058] Furthermore, the end of the side span of the continuous box girder is provided with a transverse diaphragm beam with a thickness of 2.0m.

[0059] Furthermore, the elevation difference between the upper slope and the lower slope is at least 182m.

[0060] It should be noted that the superstructure of the main bridge is a three-span prestressed concrete variable cross-section continuous box girder (80+150+80)m, with a single-span, single-box, single-cell cross-section. The top width of the box girder is 12.25m, the bottom slab width is 6.75m, and the cantilever length on both sides is 2.75m. The box girder height is 3.5m at mid-span, and the center beam height at the support is 9.5m. The beam height varies in a 1.8-degree parabola from 4.0m from the center of the main pier towards the mid-span at a distance of 70.0m. Two diaphragms, each 2.0m thick, are designed at the thin-walled positions of the main bridge box girder corresponding to the pier's central pier. A 0.5m thick mid-span transverse diaphragm is installed at the mid-span, and 2.0m thick transverse beams are installed at the ends of the side spans. Manholes are provided at the bottom slab and transverse diaphragms of the side span closure section.

[0061] It should be understood that the main pier of the continuous rigid frame adopts a uniform cross-section double-limb thin-walled pier, with pier heights of 65.675m / 49.844m (left span) and 64.017m / 58.264m (right span). The double-limb thin-walled pier has a longitudinal length of 8m, a wall thickness of 2.0m, and a transverse width of 6.75m. A transverse diaphragm with a height of 1.2m is installed in the middle of the thin-walled pier.

[0062] The main pier's pile foundation adopts a pile group foundation, consisting of nine Φ1.8m, 46m long reinforced concrete cast-in-place piles. The pile cap is 4.5m thick, with a plan dimension of 12m (longitudinal) × 12m (transverse).

[0063] It is worth noting that this bridge is a continuous box girder structure with three spans. The straight beam segments of the two side spans are 3.84m long, and the closure beam segments of the side spans and the middle span are both 2m long. The straight beam segment of the side span at pier #0 was cast in place using a disc-lock scaffold, while the straight beam segment of the side span at pier #3 was cast in place using a bracket system. The casting sequence was to cast the sections closest to the side piers first, gradually moving towards the closure section, so as to gradually adjust the elevation of each cast section and prevent the height difference between the closure section and the cantilever end from being too large.

[0064] The No. 0 abutment crosses the straight section inside the Gongtan Tunnel, employing a 60-type disc-lock scaffold with a full-span scaffold spacing of 60cm x 60cm x 60cm. I16 I-beams are installed on top of the scaffold. The scaffold foundation is situated on rock with sufficient bearing capacity. The foundation is hardened with 20cm thick C30 concrete, and a bottom formwork is laid on top of the scaffold. The inner formwork uses a combined steel frame supplemented with bamboo plywood, while the outer formwork uses standardized steel molds. Concrete is pumped into the molds for pouring.

[0065] The straight section of the side span of Pier #3 was constructed on scaffolding, with the bottom formwork laid on top. The inner formwork used a combined steel frame supplemented with bamboo plywood, while the outer formwork used a fixed steel mold. Concrete was pumped into the formwork for pouring. The scaffolding foundation was located on rock with sufficient bearing capacity. The foundation was hardened with C30 concrete, with a thickness of 30cm.

[0066] Finally, it should be noted that the sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The above embodiments are only optional embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made under the inventive concept of the present invention using the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are all included within the patent protection scope of the present invention.

Claims

1. A method for constructing a bridge abutment inside a tunnel in a steep cliff section, wherein the steep cliff section includes an upper slope and a lower slope, characterized in that, The method includes: A rigid frame bridge was constructed inside the tunnel in the steep cliff section to form the superstructure. A double-limb thin-walled pier with equal cross-section is used, and the pile foundation is constructed inside the tunnel in the steep cliff section to form the substructure. The approach bridge superstructure is formed by using prestressed concrete T-beams, initially simply supported and then structurally continuous. Using a pileless foundation method, a cap is made on the substructure to form the bridge abutment inside the tunnel in the steep cliff section; The main bridge's superstructure is a rigid frame bridge, while the substructure uses equal-section, double-limb thin-walled piers and pile foundations.

2. The construction method for a bridge abutment inside a tunnel in a steep cliff section as described in claim 1, characterized in that, The superstructure includes a three-span prestressed concrete variable cross-section continuous box girder, which is a single-span, single-box, single-cell cross-section structure.

3. The construction method for a bridge abutment inside a tunnel in a steep cliff section as described in claim 2, characterized in that, The continuous box girder has a top width of 12.25m, a bottom plate width of 6.75m, and cantilever lengths of 2.75m on both sides.

4. The construction method for a bridge abutment inside a tunnel in a steep cliff section as described in claim 3, characterized in that, The continuous box girder has a mid-span height of 3.5m and a center beam height of 9.5m at the support. The beam height varies in a 1.8-fold parabola from 4.0m from the center of the main pier towards the mid-span at a distance of 70.0m.

5. The construction method for a bridge abutment inside a tunnel in a steep cliff section as described in claim 4, characterized in that, The continuous box girder has two first diaphragms at the thin-walled position of the pier corresponding to the middle pier.

6. The construction method for a bridge abutment inside a tunnel in a steep cliff section as described in claim 5, characterized in that, The thickness of the first partition is 2.0m.

7. The construction method for a bridge abutment inside a tunnel in a steep cliff section as described in claim 6, characterized in that, A second diaphragm is provided at the mid-span of the continuous box girder.

8. The construction method for a bridge abutment inside a tunnel in a steep cliff section as described in claim 7, characterized in that, The thickness of the second partition is 0.5m.

9. The construction method for a bridge abutment inside a tunnel in a steep cliff section as described in claim 8, characterized in that, The continuous box girder has a 2.0m thick transverse diaphragm at the end of each side span.

10. The construction method for a bridge abutment inside a tunnel in a steep cliff section as described in any one of claims 1 to 9, characterized in that, The elevation difference between the upper slope and the lower slope is at least 182m.

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