Inclined shaft embedded arch seat structure and construction method thereof

Abstract

The present invention discloses an inclined shaft embedded arch seat structure and a construction method thereof, wherein the inclined shaft embedded arch seat structure comprises: two inclined shaft foundations and a tie beam arranged therebetween, wherein both ends of the tie beam are fixedly connected to the inclined shaft foundations; the cross-sectional shape of the inclined shaft foundation is a gate-type cross-section with a circular arc at the top; piers are symmetrically arranged on the two inclined shaft foundations; the inclined shaft foundation and the piers are partially embedded in the rock mass; the inclined shaft foundation is arranged obliquely, and the center line is parallel to the arch axis of the arch bridge. The present invention solves the problems of large earthwork excavation and unclear force on the arch seat foundation in the existing arch seat foundation forms; effectively improves the construction efficiency of the arch seat structure, and realizes the rapid construction of the arch seat structure of the arch bridge in the canyon in the mountainous area.

Description

Technical Field

[0001] The present invention relates to the technical field of arch bridge abutment construction, and more specifically, to an inclined shaft embedded abutment structure and a construction method thereof. Background Art

[0002] As one of the main load-bearing components of an arch bridge structure, the arch seat has a structural form and load-bearing performance that affect the durability and safety of the bridge. There are three main types of traditional arch seat structures: (1) expanded foundation type; (2) inclined pile foundation type; and (3) vertical pile foundation type. Although the expanded foundation type arch seat has a higher bearing capacity, it increases the size of the arch seat, which increases the amount of reinforced concrete and the amount of earthwork excavation, thereby increasing the construction cost. The inclined pile foundation type arch seat is suitable for situations with a relatively wide construction platform, but it is difficult to construct on steep rock walls in mountainous areas, and the construction accuracy is difficult to ensure. According to the characteristics of the arch bridge structure, it has a huge horizontal thrust at the arch seat, and the vertical pile foundation has a poor ability to resist horizontal thrust. It is necessary to further increase the number of pile foundations to ensure the safety of the structure, thereby increasing the construction cost. With the development of arch bridges, a penetration arch seat foundation has also appeared. After the foundation excavation is completed by layered and graded excavation, the steel bars are manually tied one by one in situ. There are problems such as low construction efficiency, difficulty in ensuring construction accuracy, long labor working time within the foundation and high safety risks. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0004] In order to achieve these purposes and other advantages according to the present invention, there is provided an inclined shaft embedded arch seat structure, comprising: two inclined shaft foundations and a tie beam arranged therebetween, wherein both ends of the tie beam are fixedly connected to the inclined shaft foundations respectively; the cross-sectional shape of the inclined shaft foundation is a portal-type cross-section with a circular arc-shaped top; pier seats are symmetrically arranged on the two inclined shaft foundations; the inclined shaft foundation and the pier seats are partially embedded in the rock mass; the inclined shaft foundation is arranged at an incline, and the center line is parallel to the arch axis of the arch bridge.

[0005] Preferably, the pier has a triangular structure, and its cross-section is a gate-like cross-section with an arc-shaped top.

[0006] Another object of the present invention is to provide a construction method for the inclined shaft embedded abutment structure, comprising the following steps:

[0007] S1. The inclined shaft foundation and the corresponding pier are taken as a whole, divided into multiple construction parts from top to bottom, and rock excavation is carried out in sequence, and support is carried out while excavation;

[0008] S2, excavating the tie beam;

[0009] S3, prefabricating the steel mesh of the inclined shaft foundation, the pier and the tie beam;

[0010] S4, setting up a formwork for the portion of the inclined shaft embedded abutment structure extending out of the rock mass;

[0011] S5. Hoist the corresponding steel mesh sheets into the excavated tunnel in order from bottom to top, and install and fix them;

[0012] S6. Pour concrete into the formwork and tunnel to complete the arch seat concrete construction.

[0013] Preferably, in step S1, taking the bottom edge of the side where the pier is in contact with the rock mass as a reference, the horizontal plane where the bottom edge is located is the first interface, and the plane where the bottom edge is located and parallel to the bottom surface of the inclined shaft foundation is the second interface; the rock mass corresponding to the area above the first interface is the first construction area, the rock mass corresponding to the area between the first interface and the second interface is the second construction area, and the rock mass corresponding to the area between the second interface and the bottom surface of the inclined shaft foundation is the third construction area.

[0014] Preferably, in step S1, construction area 1 and construction area 2 are excavated in turn by weak blasting, and both construction parts are excavated vertically in layers, with each layer having a vertical height of no more than 3m. Excavation and support are provided while the next layer is excavated, and excavation of the next layer is carried out after the support structure of the previous layer is completed.

[0015] Preferably, each layer of excavation is carried out in the order of determining the location of the blasthole, drilling, blasting, slag removal, and support structure construction; the support structure includes anchor rods of unequal lengths arranged along the side walls of each construction part, prestressed anchor cables arranged on the arc-shaped side of each construction part, and a first arch frame matching the cross-sectional shape of each construction part.

[0016] Preferably, after the excavation of the first construction area is completed, the first interface is used as a construction platform to carry out advanced pipe-roof support for the remaining rock mass corresponding to the inclined shaft foundation; during the excavation of the second construction area, a plain concrete cushion layer is sprayed at the second interface in a timely manner.

[0017] Preferably, the construction zone three is constructed along the axial direction of the inclined shaft foundation using the step method. After all the sections of the construction zone three have entered the excavation stage, the step method is used to excavate the distance between two second arch frames each time until all the construction zones three are excavated; the second arch frame matches the cross-sectional shape of the construction zone three.

[0018] Preferably, in step S2, the relative spatial position of the tie beam in the site topographic map is first established, and the volume of the intersection of the tie beam and the site topographic map is calculated by finite element software. If the intersecting volume is small, manual drilling is used; if the intersecting volume is large, mechanical drilling is used.

[0019] Preferably, in step S3, each steel mesh is divided into a number of flat steel meshes and arc-shaped steel meshes according to the maximum mesh size that can be produced by the steel mesh production line, the lifting capacity of the lifting equipment and the deformation limit of the steel mesh during the lifting process, and then hoisted into the tunnel for in-situ assembly.

[0020] The present invention has at least the following beneficial effects:

[0021] The inclined shaft embedded arch seat structure and the construction method thereof provided by the present invention, on the one hand, avoid the foundation construction of pier columns by arranging piers on the inclined shaft foundation, and solve the problems of large earth and stone excavation volume and unclear force of the arch seat foundation in the existing arch seat foundation form; on the other hand, a segmented and layered excavation method is adopted for the inclined shaft embedded arch seat foundation, and the steel bars are processed and formed through a steel mesh production line and then assembled in situ, and finally the arch seat concrete is poured, which effectively improves the construction efficiency of the arch seat structure and realizes the rapid construction of the arch seat structure of the arch bridge in the canyon of the mountain area.

[0022] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the inclined shaft embedded type abutment structure of the present invention;

[0024] Figure 2 It is a structural schematic diagram of the door-type section of the present invention;

[0025] Figure 3 A schematic diagram of the structure of the three construction parts divided by the inclined shaft foundation and the pier base of the present invention;

[0026] Figure 4 It is a schematic diagram of the initial support structure of the construction area 1 and the construction area 2 of the present invention;

[0027] Figure 5 This is a schematic diagram of the three-zone six-step excavation method of the present invention;

[0028] Figure 6 This is a structural schematic diagram of the present invention in which all six steps in the three construction areas have entered the excavation stage;

[0029] Figure 7 It is a schematic diagram of the structure of the steel mesh of the inclined shaft foundation of the present invention;

[0030] Figure 8 It is a schematic diagram of the structure of the flat steel mesh and the arc steel mesh of the present invention;

[0031] Fig. 9It is a schematic diagram of the structure of the planar steel mesh when connected according to the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0033] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0034] like Figure 1 and Figure 2 As shown, the present invention provides an inclined shaft embedded arch seat structure, comprising: two inclined shaft foundations 1 and a tie beam 2 arranged therebetween, wherein both ends of the tie beam 2 are fixedly connected to the inclined shaft foundations 1 respectively; the cross-sectional shape of the inclined shaft foundation 1 is a gate-type section 4 with an arc-shaped top; pier seats 3 are symmetrically arranged on the two inclined shaft foundations 1; the inclined shaft foundations 1 and the pier seats 3 are partially embedded in the rock mass; the inclined shaft foundation 1 is arranged obliquely, and the center line is parallel to the arch axis of the arch bridge.

[0035] In this technical solution, the inclined shaft embedded arch seat structure includes two inclined shaft foundations 1, the tie beam 2 connecting the two inclined shaft foundations, and the pier 3 arranged on the upper part of the inclined shaft foundation. Figure 1 The inclined shaft foundation 1 is inclined, and the center line is parallel to the arch axis of the arch bridge to improve the stress performance of the arch seat; the inclined shaft foundation 1 adopts a portal section 4, referring to Figure 2 The top of the portal section 4 is in an arc shape, which can increase the contact area between the inclined shaft foundation 1 and the rock mass and improve the stress performance during the excavation of the arch seat and arch top on the one hand, and can also reduce the amount of rock excavation and improve construction efficiency on the other hand. The tie beam 2 is arranged between the two inclined shaft foundations 1 to enhance the integrity of the arch seat structure. At the same time, the mountain can be used as a natural bottom template during the construction of the tie beam 2, and only a small amount of earth and stone needs to be excavated; preferably, the tie beam 2 is arranged parallel to the inclined shaft foundation 1. Then, the pier seat 3 of the junction pier is arranged on the upper part of the inclined shaft foundation 1. The junction pier and the arch rib share the inclined shaft foundation, which avoids the construction of the pier column foundation and reduces the construction cost.

[0036] Furthermore, the pier seat 3 is a triangular structure, and its cross-section is a gate-type section 4 with an arc-shaped top. Among the three faces of the triangle formed by the pier column 3, one side is combined with the inclined shaft foundation 1, one side is in contact with the rock mass, and the other side is exposed to the rock mass as a force-bearing surface; the pier seat 3 also adopts a gate-type section, and its contact surface with the rock mass is an arc shape, so as to improve the force-bearing performance of the pier seat 3 and reduce the amount of rock mass excavation.

[0037] The present invention also provides a construction method of the inclined shaft embedded abutment structure, comprising the following steps:

[0038] S1, the inclined shaft foundation 1 and the corresponding pier 3 are taken as a whole, divided into multiple construction parts from top to bottom, and rock excavation is carried out in sequence, and support is carried out while excavation;

[0039] S2, excavating the tie beam 2;

[0040] S3, prefabricating the steel mesh of the inclined shaft foundation 1, the pier 3 and the tie beam 2;

[0041] S4, setting up a formwork for the portion of the inclined shaft embedded abutment structure extending out of the rock mass;

[0042] S5. Hoist the corresponding steel mesh sheets into the excavated tunnel in order from bottom to top, and install and fix them;

[0043] S6. Pour concrete into the formwork and tunnel to complete the arch seat concrete construction.

[0044] In this technical solution, the two inclined shaft foundations 1 and the corresponding piers 3 are excavated simultaneously. The vertical layered and block excavation is carried out in sequence by parts, and support is carried out in time. The steel bars are processed and formed by the steel mesh production line, and then hoisted to the original site for assembly, and finally concrete is poured to complete the construction of the arch seat structure. The construction method provided by the present invention solves the problems of large earthwork excavation and low steel bar construction efficiency in the existing arch seat foundation forms, and can realize the rapid construction of the arch seat structure of the arch bridge in the mountain canyon.

[0045] First, in step S1, Figure 3As shown, taking the bottom edge of the side where the pier seat 3 contacts the rock mass as the reference, the horizontal plane where the bottom edge is located is the first interface P12, and the plane where the edge is located and parallel to the bottom surface of the inclined shaft foundation is the second interface P23; the rock mass corresponding to the first interface P12 is the construction area P1, the rock mass corresponding to the first interface P12 and the second interface P23 is the construction area P2, and the rock mass corresponding to the second interface P23 and the bottom surface of the inclined shaft foundation 1 is the construction area P3. The inclined shaft foundation 1 and the pier 3 are generally divided into three parts for excavation. Finally, the excavation method of the tie beam 2 is reasonably determined according to the relative spatial position of the tie beam 2 in the on-site topographic map, and the excavation construction of the inclined shaft embedded arch seat foundation is completed.

[0046] Before excavation, the mountain needs to be reinforced to avoid the presence of debris and other objects during foundation excavation. Construction Area 1 P1 and Construction Area 2 P2 are excavated using weak blasting methods in turn. Both construction parts are vertically excavated in layers, with each layer's vertical height not exceeding 3m. Excavation and support are carried out while the previous layer's support structure is completed before excavating the next layer.

[0047] Furthermore, each layer of excavation is carried out in the order of determining the location of blastholes, drilling, blasting, slag removal, and support structure construction; e.g. Figure 4 As shown, the support structure includes anchor rods 501 of unequal lengths arranged along the side walls of each construction section, prestressed anchor cables 502 arranged on the arc-shaped side of each construction section, and a first arch frame 503 that matches the cross-sectional shape of each construction section. During the construction of the support structure, a layer of support is completed in the order of measuring and determining the positions of the anchor rods 501 and anchor cables 502, drilling anchor rod and anchor cable holes, installing arch supports 503 and anchor rods 501 and anchor cables 502, installing steel mesh, spraying concrete, and tensioning anchor rods 501 and anchor cables 503. When each layer of rock mass is excavated, the excavation surface is a portal section, referring to Figure 2 and Figure 4 A prestressed anchor cable 502 is set on one side of the arc, and the other two side walls are reinforced with anchor rods 501 of unequal length to avoid the rock mass being stressed in the same cross-section layer; displacement measuring points are arranged on the rock wall after each layer is excavated to monitor the displacement of the rock wall in real time to ensure the safety of the foundation.

[0048] After the excavation of the first construction area is completed, the first interface P12 is used as a construction platform to carry out advanced pipe-roof support for the remaining rock mass corresponding to the inclined shaft foundation 1; during the excavation of the second construction area P2, a plain concrete cushion layer is sprayed at the second interface P23 in a timely manner. Figure 3 As shown, the excavation of construction area P2 is an inverted triangle excavation, and the excavation process is the same as that of construction area P1. During the excavation process, it is necessary to spray a thick plain concrete cushion layer in time at the interface between construction area P2 and construction area P3, that is, the second interface P23, to avoid rock collapse in construction area P3 when excavating the lower foundation.

[0049] The construction area P3 is constructed along the axis direction of the inclined shaft foundation 1 using the step method. After all sections of the construction area P3 have entered the excavation stage, the step method is used to excavate the distance between two second arch frames each time until the excavation of the construction area P3 is completed; the second arch frame matches the cross-sectional shape of the construction area P3.

[0050] Taking the six-step method as an example, the excavation process of construction zone P3 is explained in detail. Figure 5 As shown, along the cross-section direction of the inclined shaft foundation 1, there are 6 layers AF for excavation, and each layer is divided into i sections from the outside to the inside, i is an integer greater than 1, and the specific construction steps are as follows:

[0051] Sa: Excavate the A1 step on the upper side of the third construction area, spray concrete initially, install anchor rods, and set up steel mesh; erect the second arch frames 1# and 2#, lock the bottom of the arch frames with locking anchor rods 6, and spray concrete to the designed thickness; excavate the B1 step, spray concrete initially, and install anchor rods;

[0052] Sb: Repeat step Sa, excavate the A2 step and the B2 step, and erect the second arch frames 3# and 4#;

[0053] Sc: Repeat step Sb, excavate the A3 and B3 steps, erect the 5# and 6# second arch frames, and extend the 1# and 2# second arch frames, and spray concrete to the designed thickness;

[0054] Se: Repeat the above steps. After the excavation of A4 and B4 steps is completed, excavate C1 and D1 steps; then after the excavation of A5 and B5 steps is completed, excavate C2 and D2 steps; and so on. After the excavation of A7 and B7 steps is completed, excavate C4 and D4 steps, and then start excavating E1 and F1 steps. At this point, all sections of the three construction areas have entered the excavation stage. Figure 6 As shown;

[0055] Sf: Repeat the above steps, each time excavating the distance of two second arch frames along the axial direction of the inclined shaft foundation 1, that is, first excavating the upper steps A and B, then the steps C and D, and finally the steps E and F, until the entire excavation of the inclined shaft foundation 1 is completed.

[0056] In step S2, the relative spatial position of the tie beam 2 in the site topographic map is first established, and the volume of the intersection of the tie beam 2 and the site topographic map is calculated by finite element software. If the intersecting volume is small, manual drilling excavation is adopted; if the intersecting volume is large, mechanical drilling excavation is adopted.

[0057] In step S3, according to the maximum mesh size that can be produced by the steel mesh production line, the lifting capacity of the lifting equipment and the deformation limit of the steel mesh during the lifting process, each steel mesh is divided into a plurality of flat steel meshes 801 and arc steel meshes 801, such as Figure 8 As shown, after being hoisted into the tunnel, it is assembled in situ.

[0058] Taking the steel bar construction of the inclined shaft foundation 1 as an example, the steel bars of the inclined shaft foundation 1 are mainly composed of three layers of outer stirrup mesh 8, internal structural steel mesh 9 and internal longitudinal reinforcement 10. Considering the maximum mesh size that can be produced by the steel mesh production line, the lifting capacity of the lifting equipment and the deformation limit of the steel mesh during the lifting process, the steel bars of the inclined shaft foundation 1 are divided into several flat steel meshes 801 and arc-shaped steel meshes 802, which are then processed and manufactured through the production line. It should be noted that the diameter of the stirrup mesh 8 is relatively large, and the raw materials need to be threaded for subsequent connection between the steel meshes through straight threaded sleeves. The diameter of the internal structural steel mesh 9 is relatively small and can be directly connected by welding. The steel mesh after production is as follows Figure 7 shown.

[0059] In step S5, the steel bar construction is carried out in sections and blocks, and the construction is carried out in the order from construction area 3 to construction area 1. The finished steel mesh is hoisted into the tunnel, such as Fig. 9 As shown, the connection is made by welding with a straight threaded sleeve 11 or a welding rod 12. During the connection process, the connection quality at each joint needs to be ensured, and the remaining small amount of steel bars at the joint are formed by manual binding.

[0060] In step S6, since the arch seat is located in a canyon, the concrete construction is first slid to the construction platform near the arch seat through a chute; to ensure the performance of the concrete, it is mixed twice before being pumped; and then the arch seat concrete construction is completed by pouring in layers and blocks.

[0061] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A construction method for an inclined shaft embedded abutment structure, the inclined shaft embedded abutment structure comprising: Two inclined shaft foundations and a tie beam arranged therebetween, wherein both ends of the tie beam are respectively fixedly connected to the inclined shaft foundations; The cross-sectional shape of the inclined shaft foundation is a portal cross-sectional shape with an arc-shaped top; piers are symmetrically arranged on the two inclined shaft foundations; the inclined shaft foundation and the piers are partially embedded in the rock mass; the inclined shaft foundation is arranged obliquely, and the center line is parallel to the arch axis of the arch bridge; it is characterized by comprising the following steps: S1. The inclined shaft foundation and the corresponding pier are taken as a whole, divided into multiple construction parts from top to bottom, and rock excavation is carried out in sequence, and support is carried out while excavation; S2, excavating the tie beam; S3, prefabricating the steel mesh of the inclined shaft foundation, the pier and the tie beam; S4, setting up a formwork for the portion of the inclined shaft embedded abutment structure extending out of the rock mass; S5. Hoist the corresponding steel mesh sheets into the excavated tunnel in order from bottom to top, and install and fix them; S6. Pour concrete into the formwork and tunnel to complete the arch seat concrete construction; In step S1, taking the bottom edge of the side where the pier is in contact with the rock mass as a reference, the horizontal plane where the bottom edge is located is the first interface, and the plane where the bottom edge is located and parallel to the bottom surface of the inclined shaft foundation is the second interface; the rock mass corresponding to the area above the first interface is the first construction area, the rock mass corresponding to the area between the first interface and the second interface is the second construction area, and the rock mass corresponding to the area between the second interface and the bottom surface of the inclined shaft foundation is the third construction area.

2. The construction method of the inclined shaft embedded abutment structure according to claim 1, characterized in that: The pier seat is in a triangular structure, and its cross-section is a gate-type cross-section with an arc-shaped top.

3. The construction method of the inclined shaft embedded arch seat structure according to claim 1, characterized in that: In step S1, construction area 1 and construction area 2 are excavated in turn using weak blasting method. Both construction parts are excavated vertically in layers, and the vertical height of each layer does not exceed 3m. Support is provided while excavating. After the support structure of the previous layer is completed, the excavation of the next layer is carried out.

4. The construction method of the inclined shaft embedded abutment structure according to claim 3, characterized in that: The excavation of each layer is carried out in the order of determining the location of the blasthole, drilling, blasting, slag removal, and construction of the support structure; the support structure includes anchor rods of unequal lengths arranged along the side walls of each construction part, prestressed anchor cables arranged on the arc-shaped side of each construction part, and a first arch frame matching the cross-sectional shape of each construction part.

5. The construction method of the inclined shaft embedded arch seat structure according to claim 3, characterized in that: After the excavation of the first construction area is completed, the first interface is used as a construction platform to carry out advanced pipe-roof support for the remaining rock mass corresponding to the inclined shaft foundation; during the excavation of the second construction area, a plain concrete cushion layer is sprayed at the second interface in a timely manner.

6. The construction method of the inclined shaft embedded arch seat structure according to claim 1, characterized in that: The construction zone three is constructed along the axial direction of the inclined shaft foundation using the step method. After all the sections of the construction zone three have entered the excavation stage, the step method is used to excavate the distance between two second arch frames each time until all the excavation of the construction zone three is completed; the second arch frame matches the cross-sectional shape of the construction zone three.

7. The construction method of the inclined shaft embedded arch seat structure according to claim 1, characterized in that: In step S2, the relative spatial position of the tie beam in the site topographic map is first established, and the volume of the intersection of the tie beam and the site topographic map is calculated by finite element software. If the intersecting volume is small, manual drilling excavation is adopted; if the intersecting volume is large, mechanical drilling excavation is adopted.

8. The construction method of the inclined shaft embedded abutment structure according to claim 1, characterized in that: In step S3, according to the maximum mesh size that can be produced by the steel mesh production line, the lifting capacity of the lifting equipment and the deformation limit of the steel mesh during the lifting process, each steel mesh is divided into several flat steel meshes and arc steel meshes, and then hoisted into the tunnel for in-situ assembly.

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