A tilt frame pile foundation abutment structure and construction method

Abstract

A method for constructing and building an inclined frame-type pile foundation arch abutment is disclosed to significantly reduce the excavation and masonry work required for the arch abutment foundation, minimize environmental damage, and meet structural safety, durability, and engineering economic requirements. The method includes large-diameter inclined piles and an arch chord. The large-diameter inclined piles consist of two lower large-diameter inclined piles and two upper large-diameter inclined piles spaced apart transversely to the bridge. The tops of adjacent large-diameter inclined piles are fixed to tie beams, forming a frame structure. The arch chord includes a lower chord and an upper chord, which are fixedly connected to the tops of the corresponding large-diameter inclined piles via a steel-concrete connection. The large-diameter inclined piles are inclined and embedded in the rock mass, forming inclination angles α and β with the resultant force direction of the arch foot in the longitudinal and transverse directions, respectively.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, specifically to an inclined frame-type pile foundation arch abutment structure and construction method. Background Technology

[0002] With the rapid development of highway bridge construction in my country, the design process has increasingly encountered projects requiring long-span arch bridges to cross high mountains and deep valleys. Arch bridges are highly adaptable to mountainous environments, aesthetically pleasing, and have strong spanning capabilities, making them particularly suitable for V-shaped deep valley terrain. Furthermore, arch bridges offer good durability, low maintenance costs, and low construction costs. Due to these characteristics, arch bridges have seen rapid development in my country's highway bridge construction. Examples include the Xiangxi Yangtze River Highway Bridge with a main span of 519m (calculated span), the Tian'e Longtan Grand Bridge with a main span of 600m (calculated span), the Pingnan Third Bridge with a main span of 575m (calculated span), and the Hejiang Yangtze River Bridge with a main span of 530m (calculated span), among other long-span arch bridges.

[0003] For long-span arch bridges, the arch bridge itself has a large self-weight, and its load is transferred to the foundation through the arch abutment foundation. Therefore, this type of bridge has high requirements for the bearing capacity of the foundation. However, poor geological conditions with weak foundation bearing capacity greatly limit the construction of arch bridges, which is a great challenge for designers.

[0004] Taking the construction of a steel truss arch bridge with a main span of 580m (calculated span) under geological conditions of moderately weathered mudstone with a foundation bearing capacity of 500KPa as an example, if the traditional enlarged foundation scheme is adopted, it is necessary to increase the contact area between the arch abutment and the soil. The size of the arch abutment is relatively large, and the amount of concrete required is at least 60,000 m³. 3 Furthermore, the excavation volume for the arch abutment is very large, resulting in a significant environmental impact. If a composite pile foundation scheme is adopted, the pile foundation is subject to complex stresses, the load-sharing ratio is unclear, and vertical and inclined piles cannot be constructed simultaneously, leading to a long construction period.

[0005] Therefore, in order to address the shortcomings of the above solutions, an inclined frame-type pile foundation arch structure was invented, which is particularly suitable for constructing steel truss arch bridges on poor geological conditions with weak foundation bearing capacity. Summary of the Invention

[0006] The technical problem this institute aims to solve is to provide an inclined frame-type pile foundation arch abutment structure that significantly reduces the amount of excavation and masonry work required for the arch abutment foundation, minimizes environmental damage, and meets the requirements of structural safety, durability, and engineering economy.

[0007] The technical solution adopted to solve this technical problem is as follows:

[0008] This invention discloses an inclined frame-type pile foundation arch abutment structure, comprising large-diameter inclined piles and an arch chord, characterized in that: the large-diameter inclined piles consist of two lower large-diameter inclined piles and two upper large-diameter inclined piles spaced apart in the transverse direction of the bridge, with the tops of adjacent large-diameter inclined piles fixed to the tie beam to form a frame structure; the arch chord includes a lower chord and an upper chord, which are fixedly connected to the tops of the corresponding large-diameter inclined piles through a steel-concrete connection structure; the large-diameter inclined piles are inclined and embedded in the rock mass, forming inclination angles α and β with the resultant force direction of the arch foot in the longitudinal direction and transverse direction of the bridge, respectively.

[0009] The tilt angle α is calculated using the following formula:

[0010] Inclination angle α = α1 - α2

[0011] sinα2=(N*sinα1+G) / (N*cosα1)

[0012] In the formula: α1 is the angle between the axial force at the top of the arch seat and the horizontal direction, α2 is the angle between the axial force of the arch seat foundation and the horizontal direction, N is the axial force transmitted from the arch ring chord to the arch seat foundation, and G is the self-weight of the tie beam.

[0013] The inclination angle β is the angle between the principal chord and the vertical plane, which is calculated based on the bridge structure.

[0014] Another technical problem to be solved by the present invention is to provide a construction method for the above-mentioned inclined frame pile foundation arch abutment structure, comprising the following steps:

[0015] S1: Clean the foundation surface, excavate the large-diameter inclined pile opening on the upper side, set up a drainage system at the top and bottom of the slope, and take precautions against falling rocks.

[0016] S2: Construct the upper pile sleeve arch and pipe shed, and fix the guide pipe on the steel frame inside the upper pile sleeve arch;

[0017] S3: Excavate the upper large-diameter inclined pile hole using the drill and blast method, excavate along the pile axis with equal cross sections, and insert small guide pipes or anchors 91 into the surrounding rock along the pile radial direction during construction to initially support the foundation around the pile diameter.

[0018] S4: Pour concrete into the upper large-diameter inclined pile body;

[0019] S5: Remove the upper pile arch and support, excavate the lower large-diameter inclined pile opening, set up a side intercepting drainage system at the top and bottom of the slope, and take precautions against falling rocks.

[0020] S6: Construct the lower pile sleeve arch and pipe shed, and fix the guide pipe on the steel frame inside the lower pile sleeve arch;

[0021] S7: Excavate the lower large-diameter inclined pile tunnel using the drill-and-blast method, excavating along the pile axis with equal cross sections. During construction, small guide pipes or anchors are inserted into the surrounding rock along the pile radial direction to initially support the foundation around the pile diameter.

[0022] S8: Pour concrete into the lower large-diameter inclined pile body;

[0023] S9: Remove the lower pile arch and support;

[0024] S10: Construction steel-concrete connection structure;

[0025] S11: Pour concrete for the tie beam.

[0026] The beneficial effects of this invention are mainly reflected in the following aspects:

[0027] 1. Large-diameter inclined pile foundations are embedded obliquely into poor geological conditions with weak bearing capacity. The inclined pile foundations are connected by tie beams to form a frame structure, thereby improving the overall stability of the arch seat.

[0028] Second, by adjusting the inclination angle of each inclined pile and setting eccentricity, the inclined pile is subjected to axial compression, and the upper load is directly transferred to the inclined pile foundation through the steel-concrete connection structure, and finally transferred to the depth of the foundation. The load transfer path is clear, and the foundation stress is simple and reasonable.

[0029] Third, under the same geological conditions, compared with composite pile foundations and traditional enlarged foundations, this arch foundation structure has a smaller excavation volume, smaller masonry volume, lighter weight, shorter construction period, lower construction support cost, better economy, and better overall stability. Attached Figure Description

[0030] This instruction manual includes the following fourteen figures:

[0031] Figure 1 This is an elevation view of an inclined frame-type pile foundation arch structure according to the present invention;

[0032] Figure 2 This is a plan view of a large-diameter inclined pile in an inclined frame-type pile foundation arch structure according to the present invention;

[0033] Figure 3 This is a perspective view of an inclined frame-type pile foundation arch structure according to the present invention;

[0034] Figure 4 This is a plan view of the upper end of a large-diameter inclined pile in an inclined frame-type pile foundation arch structure of the present invention;

[0035] Figures 5 to 8 This is a cross-sectional view of a large-diameter inclined pile in an inclined frame-type pile foundation arch structure according to the present invention;

[0036] Figures 9 to 12A schematic diagram of the construction process of an inclined frame-type pile foundation arch seat structure according to the present invention.

[0037] The diagram shows the components and their corresponding markings: lower large-diameter inclined pile 11, upper large-diameter inclined pile 12, pile bottom enlarged head 13, tie beam 20, lower chord 31, upper chord 32, outer concrete layer 40, steel-concrete connection structure 50, upper pile construction platform 61, lower pile construction platform 62, upper intercepting drainage system 71, lower intercepting drainage system 72, upper pile sleeve arch 81, lower pile sleeve arch 82, pipe roof 90, small guide pipe or anchor 91. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] Reference Figures 1 to 4 This invention discloses an inclined frame-type pile foundation arch abutment structure comprising large-diameter inclined piles and an arch chord. The large-diameter inclined piles consist of two lower large-diameter inclined piles 11 and two upper large-diameter inclined piles 12 spaced apart transversely. The tops of adjacent large-diameter inclined piles are fixed to a tie beam 20, forming a frame structure and improving the overall stability of the inclined pile foundation. The arch chord includes a lower chord 31 and an upper chord 32. The lower chord 31 and upper chord 32 are fixedly connected to the tops of the corresponding large-diameter inclined piles via a steel-concrete connection structure 50, ensuring a clear and reasonable load transfer path.

[0040] Based on the stress characteristics of arch bridges, the large-diameter inclined piles are embedded in the rock mass at an angle α and an angle β with the resultant force direction of the arch foot in the longitudinal and transverse directions of the bridge, respectively.

[0041] The tilt angle α is calculated using the following formula:

[0042] Inclination angle α = α1 - α2

[0043] sinα2=(N*sinα1+G) / (N*cosα1)

[0044] In the formula: α1 is the angle between the axial force at the top of the arch seat and the horizontal direction, α2 is the angle between the axial force of the arch seat foundation and the horizontal direction, N is the axial force transmitted from the arch ring chord to the arch seat foundation, and G is the self-weight of the tie beam.

[0045] The inclination angle β is determined based on the bridge structure calculation.

[0046] The inclination angle β is the angle between the principal chord and the vertical plane. According to the bridge structure calculation, if it is a parallel arch, the inclination angle is 0 degrees, and if it is a basket arch, the inclination angle β ≠ 0 degrees.

[0047] The lower large-diameter inclined pile 11 and the upper large-diameter inclined pile 12 are preferably reinforced concrete piles. The loads on the lower chord 31 and upper chord 32 of the truss arch are directly transferred to the depth of the foundation through the pile foundation. (Refer to...) Figure 1 To increase the bearing capacity of the foundation, the lower end of the large-diameter inclined pile has an enlarged head 13, the diameter of which is 1.5 to 2.5 times the pile diameter. (Refer to...) Figures 5 to 8 The cross-section of the large-diameter inclined pile is circular, round-ended, solid, or hollow. To reduce masonry work, the upper and lower ends of the large-diameter inclined pile are solid, while the middle part is hollow. The pile diameter and length of the large-diameter inclined pile are adjusted based on the pile top reaction force calculation, and the axial compression of the inclined pile foundation is achieved by adjusting the inclination angle of each large-diameter inclined pile and setting eccentricity.

[0048] Reference Figure 1 The lower chord 31 and the upper chord 32 are provided with an outer concrete layer 40 on the outer wall near the steel-concrete connection structure 50, which can resist falling rocks and increase the safety of the chord.

[0049] Reference Figures 9 to 12 The present invention discloses a construction method for an inclined frame pile foundation arch abutment structure, comprising the following steps:

[0050] S1: Clean the foundation surface, excavate the 12 holes of the large-diameter inclined piles on the upper side, set up the drainage system 71 at the top and bottom of the slope, and take protective measures against falling rocks.

[0051] S2: Construct the upper pile sleeve arch 81 and pipe shed 90, and fix the guide pipe on the steel frame inside the upper pile sleeve arch 81;

[0052] S3: Excavate the upper large-diameter inclined pile 12 tunnel body by drilling and blasting method, excavate along the pile axis with equal cross section, and insert small guide pipes or anchors 91 into the surrounding rock body along the pile radial direction during construction to initially support the foundation around the pile diameter.

[0053] S4: Pour concrete into the body of the 12 large-diameter inclined piles on the upper side;

[0054] S5: Remove the upper pile arch 81 and support, excavate the lower large-diameter inclined pile 11 opening, set up a side intercepting drainage system 72 at the top and bottom of the slope, and take measures to prevent dangerous rocks from falling.

[0055] S6: Construct the lower pile sleeve arch 82 and pipe roof 90, and fix the guide pipe on the steel frame inside the lower pile sleeve arch 82;

[0056] S7: Excavate the lower large-diameter inclined pile 11 tunnel body by drilling and blasting, excavate along the pile axis with equal cross section, and insert small guide pipes or anchors 91 into the surrounding rock body along the pile radial direction during construction to initially support the foundation around the pile diameter.

[0057] S8: Pour concrete into the lower large-diameter inclined pile 11;

[0058] S9: Remove the lower side pile arch 82 and its support;

[0059] S10: Construction steel-concrete connection structure 50;

[0060] S11: Pour 20 mm of concrete for the tie beam.

[0061] In steps S2 and S6, the upper pile sleeve arch 8 and the lower pile sleeve arch 82 are reinforced concrete structures. When installing the guide pipe, the upper platform should be reserved and the inclination angle of the steel pipe should be controlled to ensure that the hole orientation is correct.

[0062] In steps S3 and S7, geological forecasting should be carried out during full-section excavation, and the stability of the tunnel structure should be monitored in real time. If the stability of the tunnel structure is poor, a grid steel frame should be installed to strengthen the support.

[0063] In steps S4 and S8, the concrete for the large-diameter pile body is poured in batches, with upper and lower layers. Cooling water pipes are embedded in the concrete to control the temperature of the poured concrete and avoid large-volume concrete pouring cracks.

[0064] The above description is merely an illustration of some principles of the inclined frame pile foundation arch abutment structure and construction method of the present invention, and is not intended to limit the invention to the specific structures and steps shown and described. Therefore, all possible modifications and equivalents are within the scope of the patent application of the present invention.

Claims

1. An inclined frame-type pile foundation arch abutment structure, comprising large-diameter inclined piles and an arch chord, characterized in that: The large-diameter inclined piles consist of two lower large-diameter inclined piles (11) and two upper large-diameter inclined piles (12) spaced apart in the transverse direction of the bridge. The tops of adjacent large-diameter inclined piles are fixed to the tie beam (20) to form a frame structure. The arch chord includes a lower chord (31) and an upper chord (32). The lower chord (31) and the upper chord (32) are fixedly connected to the tops of the corresponding large-diameter inclined piles through a steel-concrete connection structure (50). The large-diameter inclined piles are inclined and embedded in the rock mass, forming inclination angles α and β with the resultant force direction of the arch foot in the longitudinal direction and transverse direction of the bridge, respectively. The tilt angle α is calculated using the following formula: Inclination angle α = α1 - α2 sinα2=(N*sinα1+G) / (N*cosα1) In the formula, α1 is the angle between the axial force at the top of the arch seat and the horizontal direction, α2 is the angle between the axial force of the arch seat foundation and the horizontal direction, N is the axial force transmitted from the arch ring chord to the arch seat foundation, and G is the self-weight of the tie beam. The inclination angle β is the angle between the principal chord and the vertical plane, which is determined by calculation based on the bridge structure.

2. The inclined frame-type pile foundation arch abutment structure as described in claim 1, characterized in that: The lower end of the large-diameter inclined pile has an enlarged head (13) at the bottom, the diameter of which is 1.5 to 2.5 times the pile diameter.

3. The inclined frame-type pile foundation arch abutment structure as described in claim 1, characterized in that: The upper and lower ends of the large-diameter inclined pile are solid sections, while the middle part is a hollow section.

4. The inclined frame-type pile foundation arch abutment structure as described in claim 1, characterized in that: The lower chord (31) and upper chord (32) are provided with an outer concrete layer (40) on the outer wall of the steel-concrete connection structure (50).

5. A construction method for an inclined frame-type pile foundation arch abutment structure as described in any one of claims 1 to 4, comprising the following steps: S1: Clean the foundation surface, excavate the upper large-diameter inclined pile (12) opening, set up a drainage system (71) at the top and bottom of the slope, and take measures to prevent dangerous rocks from falling. S2: Construct the upper pile sleeve arch (81) and pipe shed (90), and fix the guide pipe on the steel frame inside the upper pile sleeve arch (81); S3: Excavate the upper large-diameter inclined pile (12) tunnel body by drilling and blasting method, excavate along the pile axis with equal cross section, and insert small guide pipes or anchors (91) into the surrounding rock body along the pile radial direction during construction to initially support the foundation around the pile diameter; S4: Pour concrete into the upper large-diameter inclined pile (12); S5: Remove the upper pile arch (81) and support, excavate the lower large-diameter inclined pile (11) opening, set up a side intercepting drainage system (72) at the top and bottom of the slope, and take measures to prevent dangerous rocks from falling. S6: Construct the lower pile sleeve arch (82) and pipe shed (90), and fix the guide pipe on the steel frame inside the lower pile sleeve arch (82); S7: Excavate the lower large-diameter inclined pile (11) tunnel body by drilling and blasting, excavate along the pile axis with equal cross section, and insert small guide pipes or anchors (91) into the surrounding rock body along the pile radial direction during construction to initially support the foundation around the pile diameter; S8: Pour concrete into the lower large-diameter inclined pile (11); S9: Remove the lower side pile arch (82) and support; S10: Construction steel-concrete connection structure (50); S11: Pour concrete for the tie beam (20).

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