阅读说明：本技术 一种隧道十字交叉口结构及其施工方法 (Tunnel crossroad structure and construction method thereof ) 是由 李习平 王振纲 曾凡云 王宏贵 侯文韬 刘德煊 于 2021-08-24 设计创作，主要内容包括：本发明提供一种隧道十字交叉口结构及其施工方法。所述隧道十字交叉口结构包括交叉口部,所述交叉口部包括下部直墙结构和上部穹顶结构；每隔一个所述直墙上设置一个支洞；所述交叉口部紧贴围岩设有初期支护；所述支洞紧贴围岩依次设有初期支护和二次衬砌；所述支洞的初期支护处设有多根打入围岩的砂浆锚杆及挂设有钢筋网；沿所述支洞的纵向设置多榀钢拱架；所述交叉口部下部设有多根打入围岩的砂浆锚杆和预应力锚杆及挂设有钢筋网；沿每条所述同心圆锚杆布置线上交错布置有多根打入围岩的砂浆锚杆、预应力锚杆及挂设有钢筋网。与相关技术相比,本发明使得在地质条件较好的Ⅱ级、Ⅲ级围岩地段洞内开挖大跨穹顶十字交叉口成为可能。(The invention provides a tunnel intersection structure and a construction method thereof. The tunnel intersection structure comprises an intersection opening part, and the intersection opening part comprises a lower straight wall structure and an upper dome structure; arranging branch holes on every other straight wall; the cross opening is provided with a primary support close to the surrounding rock; the branch tunnel is sequentially provided with a primary support and a secondary lining close to the surrounding rock; a plurality of mortar anchor rods for driving into surrounding rocks and a reinforcing mesh hung at the primary support position of the branch tunnel; a plurality of steel arch frames are arranged along the longitudinal direction of the branch tunnel; the lower part of the cross opening part is provided with a plurality of mortar anchor rods and prestressed anchor rods which are driven into surrounding rock, and a reinforcing mesh is hung on the mortar anchor rods and the prestressed anchor rods; and a plurality of mortar anchor rods and prestressed anchor rods which are driven into the surrounding rock are arranged on each concentric anchor rod arrangement line in a staggered manner, and a reinforcing mesh is hung on each concentric anchor rod arrangement line. Compared with the related technology, the invention makes it possible to dig the cross intersection across the dome in the level II and level III surrounding rock section holes with better geological conditions.)

1. A tunnel intersection structure is characterized by comprising a crossing opening part (1), wherein the crossing opening part (1) comprises a lower straight wall structure (101) and an upper dome structure (102) arranged at the upper end of the lower straight wall structure (101); the upper dome structure (102) is a shell structure with a spherical surface; the lower straight wall structure (101) is an eight-straight wall structure which forms a symmetrical eight-side straight wall structure; a branch hole (9) is arranged on every other straight wall, and the branch holes (9) are communicated with the intersection parts (1);

the cross opening (1) is provided with a primary support (10) closely attached to surrounding rocks; the branch tunnel (9) is tightly attached to surrounding rocks and is sequentially provided with a primary support (10) and a secondary lining (11);

a plurality of mortar anchor rods (7) which are driven into surrounding rocks are arranged at the primary support position of the branch hole (9), and a reinforcing mesh is hung between the mortar anchor rods (7); a plurality of steel arch frames (6) are arranged along the longitudinal direction of the branch tunnel (9), and the steel arch frames (6) are connected in a staggered mode on the inner side and the outer side of each steel arch frame (6) through connecting steel bars (13);

a plurality of mortar anchor rods (7) and prestressed anchor rods (8) which are driven into surrounding rock are arranged in a staggered manner in the primary support of the straight wall structure (101) at the lower part of the cross port part (1), and a reinforcing mesh is hung between the mortar anchor rods (7) and the prestressed anchor rods (8);

the center vertex of a dome structure (102) at the upper part of the cross opening part (1) is provided with one prestressed anchor rod (8), the center vertex is sequentially and radially outwards radial from the vertex, a plurality of concentric anchor rod arrangement lines (14) are annularly arranged, a plurality of mortar anchor rods (7) and prestressed anchor rods (8) which are driven into surrounding rock are arranged on each concentric anchor rod arrangement line (14) in a staggered mode, and a reinforcing mesh is hung between the mortar anchor rods (7) and the prestressed anchor rods (8).

2. A tunnel intersection structure according to claim 1, wherein 6n mortar anchor rods (7) and prestressed anchor rods (8) are alternately arranged on the nth concentric circle in the plurality of concentric circle anchor rod arrangement lines (14), wherein n is a natural number > 0, 3n are the mortar anchor rods (7), 3n are the prestressed anchor rods (8), and the number of the mortar anchor rods (7) is the same as that of the prestressed anchor rods (8).

3. A tunnel intersection structure according to claim 1 or 2, wherein two steel arches (6) are provided at the junction of each branch tunnel (9) and the intersection (1).

4. A tunnel intersection structure according to claim 1 or 2, further comprising a plurality of connecting steel bars (13), wherein the steel arches (6) are connected in a staggered manner inside and outside the steel arches (6) through the connecting steel bars (13).

5. A tunnel intersection structure according to claim 1 or 2, wherein the three-dimensional surrounding rock excavation area defined by the outer surface of the lower vertical wall structure (101) forms a lower step, and the three-dimensional surrounding rock excavation area defined by the outer surface of the upper dome structure (102) forms an upper step.

6. A construction method of a tunnel intersection structure as claimed in any one of claims 1 to 5, comprising the steps of:

1) excavating one of the branch holes (9), after forming, primarily spraying concrete to seal the surrounding rock, then arranging a mortar anchor rod (7), hanging a reinforcing mesh and erecting a steel arch frame (6) towards the surrounding rock, and spraying concrete again;

2) excavating a sector subsection of an upper step of the cross opening (1) close to the branch hole (9), primarily spraying concrete after molding, then drilling a mortar anchor rod (7) and a prestressed anchor rod (8) towards surrounding rocks, hanging a reinforcing mesh, and then re-spraying the concrete to form a primary support (10);

3) sequentially excavating other sector subsections of the upper step of the cross opening part (1) in an annular subsection mode, after each sector subsection is excavated and formed, primarily spraying concrete according to the method in the step 2), arranging a mortar anchor rod (7) and a prestressed anchor rod (8), hanging a reinforcing mesh, and then re-spraying the concrete to form a primary support (10), and circulating the steps until the whole upper step is excavated, formed by support and formed to form an upper dome structure (102) of the cross opening part (1);

4) sequentially excavating lower steps of the cross opening part (1) in an annular subsection mode, starting from a straight wall section close to the branch hole (9) in the step 1), after each subsection is excavated and formed, primarily spraying concrete according to the method in the step 2), drilling a mortar anchor rod (7) and a prestressed anchor rod (8), hanging a reinforcing mesh, and then spraying concrete again to form a primary support (10), circulating until the whole lower steps are excavated and formed in a supporting mode, and arranging cast-in-place side walls (12) close to the inner side of the primary support at four straight walls of the cross opening part (1) which are not communicated with the branch hole (9) to form a straight wall structure (101) at the lower part of the cross opening part (1);

5) excavating other branch holes (9) according to the method of the step 1);

6) step 4), the lower straight wall structure (101) is composed of an octahedral straight wall structure, wherein every other straight wall is communicated with the branch tunnel excavated in the step 1);

7) step 2), 3) the upper step consists of eight sector-shaped subsections; step 4) the lower step consists of eight straight wall sections;

8) and pouring all the excavated branch holes (9) to form a secondary lining (11).

7. A construction method of a tunnel intersection structure according to claim 6, characterized by further comprising a step 1.1 between the step 1) and the step 2), wherein two steel arch frames (6) are erected at the connection position of the excavated branch hole (9) and the intersection part (1) in the step 1), each steel arch frame (6) is connected from one side wall of the branch hole (9) to the other side wall, and the inner side and the outer side of each steel arch frame (6) are connected through connecting steel bars (13) in a staggered mode to form a complete arch wall supporting and reinforcing ring.

8. A method for constructing a tunnel intersection structure according to claim 6, wherein the direction of the circumferential subdivision excavation in steps 3) and 4) is clockwise or anticlockwise.

Technical Field

The invention relates to the technical field of tunnel engineering construction, in particular to a tunnel intersection structure and a construction method thereof.

Background

In the road construction in water conservancy and hydropower construction field, the situation that the route crosses in the hole exists in the design and construction of underground cavern roads under the restriction of topography. In view of the requirements of stable structure and safety, the crossroad of the tunnel is generally selected to be arranged in II-level and III-level surrounding rocks with better geological conditions.

The cross intersection structure of tunnel is characterized by that its four cross branches are made into the form of cross, and the included angle of adjacent branches is close to 90 deg.. When the intersection structure is designed, the current domestic common methods comprise two methods: the direct crossing structure is characterized in that four branches are not expanded and excavated, the excavation amount is small, the construction difficulty and the construction cost are low, and the structure stress and the traffic conditions are poor; the other type is a 'small hole and large hole' structure which is dug by expanding two branches and is not dug by expanding the other two branches, the structure is relatively well stressed, the traffic conditions are better, but the construction difficulty is higher, and the manufacturing cost is higher.

As in the prior art, patent publication No.: CN107975383A, patent name: an excavation supporting construction method for a T-shaped intersection of an underground cavern is disclosed, and the construction method comprises the following steps: CN107387131A, patent name: an asymmetric fork hole supporting structure and a construction method thereof are disclosed, and the patent publication number is as follows: CN205895242U, patent name: a tunnel structure of a small-angle intersection only relates to a T-shaped intersection or a small-angle Y-shaped intersection formed by three crossed branches in the prior art, and is not suitable for the situation of a cross intersection in a tunnel.

Therefore, when the route in the hole is crossed, the current selectable structural types are few, and the complete set of design and construction technology is few.

Disclosure of Invention

The invention aims to provide a tunnel intersection structure which is good in stress and suitable for II-level and III-level surrounding rock sections with good geological conditions and a construction method thereof.

The technical scheme of the invention is as follows: a tunnel intersection structure comprises a crossing port, wherein the crossing port comprises a lower straight wall structure and an upper dome structure arranged at the upper end of the lower straight wall structure; the upper dome structure is a shell structure with a spherical surface; the lower straight wall structure is an octahedral straight wall structure formed by eight straight walls in symmetrical distribution; a branch hole is arranged on every other straight wall and is communicated with the intersection part;

the cross opening is provided with a primary support close to the surrounding rock; the branch tunnel is sequentially provided with a primary support and a secondary lining close to the surrounding rock;

a plurality of mortar anchor rods for driving into surrounding rocks are arranged at the primary support position of the branch tunnel, and a reinforcing mesh is hung between the mortar anchor rods; a plurality of steel arches are arranged along the longitudinal direction of the branch tunnel, and the plurality of steel arches are connected in a staggered manner at the inner side and the outer side of the steel arch through connecting steel bars;

a plurality of mortar anchor rods and prestressed anchor rods which are driven into surrounding rock are arranged in a staggered manner in the primary support of the straight wall structure at the lower part of the cross opening, and a reinforcing mesh is hung between the mortar anchor rods and the prestressed anchor rods;

the central peak of the dome structure at the upper part of the cross opening part is provided with one prestressed anchor rod, the prestressed anchor rod is radial outwards in sequence from the peak, a plurality of concentric anchor rod arrangement lines are annularly arranged, a plurality of mortar anchor rods and prestressed anchor rods for driving into surrounding rock are arranged on each concentric anchor rod arrangement line in a staggered mode, and a reinforcing mesh is hung between each mortar anchor rod and each prestressed anchor rod.

In the scheme, the cross opening is of a structure that spray anchor lining is adopted, and a cast-in-place concrete side wall is arranged on the side wall of the lower part of the straight wall; the cross opening part adopts a structure which is provided with a mortar anchor rod and is reinforced by combining a prestressed anchor rod; the construction subarea of the cross opening part comprises an upper step and a lower step; the cross opening part adopts a spray anchor lining structure which is constructed by annularly constructing an upper step in a subsection mode and then constructing a lower step in an annularly subsection mode; and the reinforced structure of the combined lining (primary support and secondary lining) of the branch tunnel is combined, so that effective lateral constraint and support effects are provided for the large-span dome structure, and the safety and stability of the large-span crossroad structure in the tunnel are ensured. In addition, the octahedral straight wall structures which are basically symmetrically distributed in the lower straight wall structure can symmetrically spread four traffic branch roads on one hand, so that road routes in the tunnel are crossed in a cross shape; on the other hand, the structure symmetry can realize the stress basic symmetry, and the atress is more even, and stability is better for it becomes possible to excavate large-span dome crossroad at better II level of geological conditions, III level surrounding rock district.

Preferably, in the arrangement lines of the multiple concentric anchor rods, 6n mortar anchor rods and prestressed anchor rods are arranged on the nth concentric circle in a staggered manner, wherein n is a natural number greater than 0, 3n mortar anchor rods and 3n prestressed anchor rods are arranged, and the number of the mortar anchor rods is the same as that of the prestressed anchor rods.

Preferably, two steel arches are arranged at the connection part of each branch hole and the cross opening.

Preferably, the steel arch support further comprises a plurality of connecting steel bars, and the plurality of steel arches are connected in a staggered mode on the inner side and the outer side of each steel arch through the connecting steel bars.

Preferably, the three-dimensional surrounding rock excavation area surrounded by the outer surface of the lower straight wall structure forms a lower step, and the three-dimensional surrounding rock excavation area surrounded by the outer surface of the upper dome structure forms an upper step.

The invention also provides a construction method of the tunnel intersection structure, which comprises the following steps:

1) excavating one of the branch holes, after forming, primarily spraying concrete to seal the surrounding rock, then arranging a mortar anchor rod, hanging a reinforcing mesh and erecting a steel arch frame towards the surrounding rock, and spraying concrete again;

2) excavating a sector subsection of an upper step of the cross opening part close to the branch hole, firstly spraying concrete after forming, then drilling a mortar anchor rod and a prestressed anchor rod towards the surrounding rock, hanging a reinforcing mesh, and then spraying concrete again to form a primary support;

3) sequentially excavating the other fan-shaped subsections of the upper step of the intersection part in a mode of annular subsection, after each fan-shaped subsection is excavated and formed, primarily spraying concrete according to the method in the step 2), arranging a mortar anchor rod and a prestressed anchor rod, hanging a reinforcing mesh, and then re-spraying concrete to form an initial support, and circulating the steps until the whole upper step is excavated and formed in a supporting mode to form an upper dome structure of the intersection part;

4) sequentially excavating lower steps at the intersection part in an annular subsection mode, starting from the straight wall subsection close to the branch hole in the step 1), after each subsection is excavated and formed, primarily spraying concrete according to the method in the step 2), drilling a mortar anchor rod and a prestressed anchor rod, hanging a reinforcing mesh, and then re-spraying the concrete to form a primary support, circulating until the whole lower steps are excavated and formed by support, and arranging cast-in-place side walls close to the inner side of the primary support at four straight walls at the intersection part which are not communicated with the branch hole to form a straight wall structure at the lower part of the intersection part;

5) excavating other branch holes according to the method in the step 1);

6) step 4), the lower straight wall structure is composed of an octahedral straight wall structure, wherein every other straight wall is communicated with the branch tunnel excavated in the step 1);

7) step 2), 3) the upper step consists of eight sector-shaped subsections; step 4) the lower step consists of eight straight wall sections;

8) and pouring all the excavated branch tunnels to form a secondary lining.

According to the scheme, the new Austrian method is adopted for construction, and the self-bearing capacity of the surrounding rock is fully utilized in the good surrounding rock sections (the II-level and III-level surrounding rock sections with good geology), so that a good supporting effect is achieved.

Preferably, a step 1.1 is further included between the step 1) and the step 2), two steel arches are erected at the connecting position of the excavated branch hole formed in the step 1) and the intersection, each steel arch is connected from one side wall of the branch hole to the other side wall of the branch hole, and the inner side and the outer side of each steel arch are connected by connecting steel bars in a staggered mode to form a complete arch wall supporting and reinforcing ring.

Preferably, the direction of the annular subsection excavation in the step 3) and the step 4) is clockwise or counterclockwise.

Compared with the related technology, the invention has the beneficial effects that: the tunnel crossroad structure enables the excavation of a large-span dome crossroad to be possible in II-level and III-level surrounding rock sections with good geological conditions; the crossing mouth portion adopts spray anchor lining, the branch tunnel adopts combined type lining, and the mode that both combine makes construction convenience, make full use of country rock self-supporting ability, has reached fine supporting effect, has overcome the atress and the economic defect of traditional common way to have novel, the reasonable technological advantage of atress of structural configuration appearance.

Drawings

FIG. 1 is a schematic structural view of a cross-road tunnel intersection structure provided by the present invention;

FIG. 2 is a schematic plan view of a steel arch and anchor rods in the cross-road tunnel intersection structure provided by the present invention;

FIG. 3 is a schematic plan view of the arrangement at A in FIG. 2;

fig. 4 is a schematic perspective sectional view of a branch hole and a crossing portion in fig. 2.

In the attached drawing, 1-a cross opening, 101-a lower straight wall structure, 102-an upper dome structure, 2-a tunnel I, 3-a tunnel II, 4-a tunnel III, 5-a tunnel IV, 6-a steel arch, 7-a mortar anchor rod, 8-a pre-stressed anchor rod, 9-a tunnel, 10-primary support, 11-secondary lining, 12-a cast-in-place side wall, 13-connecting reinforcing steel bars and 14-concentric anchor rod arrangement lines.

Detailed Description

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. For convenience of description, the words "upper", "lower", "left" and "right" in the following description are used only to indicate the correspondence between the upper, lower, left and right directions of the drawings themselves, and do not limit the structure.

As shown in fig. 1 to 4, the cross intersection structure for a tunnel according to the present embodiment includes a crossing portion 1, where the crossing portion 1 includes a lower straight-wall structure 101 and an upper dome structure 102 disposed at an upper end of the lower straight-wall structure 101, and the upper dome structure 102 is a shell structure with a spherical surface. The lower straight wall structure 101 is an octahedral straight wall structure formed by eight straight walls and distributed basically and symmetrically. And a branch hole 9 is arranged on every other straight wall, and the branch holes 9 are communicated with the intersection parts 1.

The cross opening 1 is provided with a primary support 10 closely attached to the surrounding rock. The branch hole 9 is provided with a primary support 10 and a secondary lining 11 in sequence close to the surrounding rock.

The primary support department of branch hole 9 is equipped with many mortar anchor rods 7 of squeezing into the country rock, hang between mortar anchor rod 7 and be equipped with the reinforcing bar net. And a plurality of steel arch frames 6 are arranged along the longitudinal direction of the branch tunnel 9, and the plurality of steel arch frames 6 are connected in a staggered manner at the inner side and the outer side of the steel arch frame 6 through connecting steel bars 13. The branch hole 9 is provided with a primary support 10 and a secondary lining 11 in sequence close to the surrounding rock. The branch holes 9 form a composite lining structure through the combination of the primary support 10 and the secondary lining 11, so that a good reinforcing effect is achieved, an effective lateral restraining and supporting effect is provided for a long-span dome structure, and the safety and stability of the long-span crossroad structure are guaranteed.

Two steel arches 6 are arranged at the joint of each branch hole 9 and the intersection part 1, and the two steel arches 6 are connected through the connecting steel bars 13.

The primary support of the lower straight wall structure 101 of the cross opening part 1 is provided with a plurality of mortar anchor rods 7 and prestressed anchor rods 8 which are driven into the surrounding rock in a staggered mode, and a reinforcing mesh is hung between the mortar anchor rods 7 and the prestressed anchor rods 8.

The central peak of the dome structure 102 at the upper part of the crossed opening part 1 is provided with one prestressed anchor rod 8, the prestressed anchor rods are sequentially radial outwards from the peak, a plurality of concentric anchor rod arrangement lines 14 are annularly arranged, and a plurality of mortar anchor rods 7 and prestressed anchor rods 8 which are driven into the surrounding rock are arranged on each concentric anchor rod arrangement line 14 in a staggered mode. In the plurality of (n are set) concentric circle anchor rod arrangement lines 14, 6n mortar anchor rods 7 and prestressed anchor rods 8 are arranged on the nth concentric circle in a staggered manner, wherein n is a natural number greater than 0, 3n mortar anchor rods 7 and 3n prestressed anchor rods 8 are arranged, and the number of the mortar anchor rods 7 is the same as that of the prestressed anchor rods 8. And a reinforcing mesh is also hung between the prestressed anchor rod 8 and the mortar anchor rod 7.

The cross opening part 1 is provided with a flexible primary support 10 formed by the mortar anchor rod 7, the pre-stressed anchor rod 8, the reinforcing mesh and sprayed concrete in close contact with the surrounding rock, and can be well adapted to deformation of the surrounding rock.

For convenience of describing the construction method, the branch cave 9 is divided into a branch cave one 2, a branch cave two 3, a branch cave three 4 and a branch cave four 5 for description.

The invention also provides a construction method of the tunnel intersection structure, which comprises the following steps:

1) excavating one of the branch holes 9 (branch hole I2), after forming, primarily spraying concrete to seal the surrounding rock, then arranging a mortar anchor rod 7, hanging a reinforcing mesh and erecting a steel arch 6 towards the surrounding rock, erecting the connecting steel bar 13 on the steel arch 6, and spraying concrete again.

2) Two steel arches 6 are arranged at the connection part of the branch hole I2 and the cross opening part 1, each steel arch 6 extends from one side wall of the branch hole 9 to the other side wall, and the inner side and the outer side of each steel arch 6 are connected by connecting steel bars 13 in a staggered mode to form a complete arch wall supporting reinforcing ring.

3) And excavating a sector subsection of an upper step of the cross opening part 1 close to the branch hole I2, primarily spraying concrete after forming, then drilling a mortar anchor rod 7 and a prestressed anchor rod 8 towards surrounding rocks, hanging a reinforcing mesh, and then spraying concrete again to form a primary support 10.

4) And (3) sequentially excavating the other sector-shaped subsections of the upper step of the intersection part 1 in an annular subsection mode, after each sector-shaped subsection is excavated and formed, primarily spraying concrete according to the method in the step 2), arranging a mortar anchor rod 7 and a prestressed anchor rod 8, hanging a reinforcing mesh, and then spraying concrete again to form an initial support 10, and circulating the steps until the whole upper step is excavated, formed in a supporting mode, and thus the upper dome structure 102 of the intersection part 1 is formed.

5) Sequentially excavating the lower steps of the cross opening part 1 in an annular subsection mode, starting from the straight wall subsection close to the branch hole I2 in the step 1), after each subsection is excavated and formed, primarily spraying concrete according to the method in the step 2), arranging a mortar anchor rod 7 and a prestressed anchor rod 8, hanging a reinforcing mesh, and secondarily spraying concrete to form a primary support (10), and circulating until the whole lower step is excavated and formed in a supporting mode, wherein cast-in-situ side walls 12 are arranged on the four-side straight walls, which are not communicated with the branch hole I2, the branch hole II 3 and the branch hole III 4 and the branch hole IV 5, close to the inner side of the primary support, at the cross opening part 1 to form a straight wall structure 101 at the lower part of the cross opening part 1.

6) Excavating and supporting a branch tunnel II 3, a branch tunnel III 4 and a branch tunnel IV 5 according to the method in the step 1), and arranging a steel arch frame 6 and connecting steel bars 13 according to the method in the step 2).

7) And pouring a branch hole I2, a branch hole II 3, a branch hole III 4 and a branch hole IV 5 to form a secondary lining 11.

The excavation is carried out from the branch tunnel I2, and actually can be carried out from any one of the branch tunnel II 3, the branch tunnel III 4 or the branch tunnel IV 5. The circumferential distribution excavation direction may be clockwise or counterclockwise.

The lower step is a three-dimensional surrounding rock excavation area defined by the outer surface of the lower straight wall structure 101 and consists of eight straight wall sections, wherein the four straight wall sections are respectively communicated with a branch hole I2, a branch hole II 3, a branch hole III 4 and a branch hole IV 5. The upper step is a three-dimensional surrounding rock excavation area defined by the outer surface of the upper dome structure 102 and consists of eight fan-shaped subsections.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.