阅读说明：本技术 一种下穿式湖域段隧道主体结构的施工方法 (Construction method of main body structure of underpass type lake area section tunnel ) 是由 唐培文 严朝锋 刘冰 樊涛 孙伟夫 马立云 薛青松 魏宗华 卫凯 刘强 王小兵 于 2021-08-31 设计创作，主要内容包括：本发明公开了一种下穿式湖域段隧道主体结构的施工方法,隧道主体结构沿其长度方向划分为主体施工段落、过渡施工段落和超宽叠型施工段落；主体施工段落的施工方法、过渡施工段落的施工方法和超宽叠型施工段落的施工方法均相同,该施工方法包括：一、开挖施工,并施工基底垫层；二、沿开挖方向由下至上将主体施工段落的横断面、过渡施工段落的横断面和超宽叠型施工段落的横断面均划分为多个施工层；三、同时施工主体施工段落、过渡施工段落和超宽叠型施工段落。本发明能够保证湖域段隧道结构具有准确的延伸方向,能够大大缩短湖域段隧道结构的施工工期,能够在湖底形成一个稳定平衡的施工空间,能够避免在湖底出现基坑安全的问题。(The invention discloses a construction method of a main body structure of a downward-penetrating lake area section tunnel, wherein the main body structure of the tunnel is divided into a main body construction section, a transition construction section and an ultra-wide overlapped construction section along the length direction of the main body structure; the construction method of the main body construction section, the construction method of the transition construction section and the construction method of the ultra-wide overlapped construction section are the same, and the construction method comprises the following steps: firstly, excavating construction, and constructing a base cushion layer; dividing the cross section of the main construction section, the cross section of the transition construction section and the cross section of the ultra-wide overlapped construction section into a plurality of construction layers from bottom to top along the excavation direction; and thirdly, simultaneously constructing a main body construction section, a transition construction section and an ultra-wide overlapped construction section. The method can ensure that the tunnel structure of the lake area section has an accurate extension direction, can greatly shorten the construction period of the tunnel structure of the lake area section, can form a stable and balanced construction space at the bottom of the lake, and can avoid the problem of foundation pit safety at the bottom of the lake.)

1. A construction method of a main body structure of a downward-penetrating type lake area section tunnel is characterized by comprising the following steps: the tunnel main body structure is divided into a main body construction section (22), a transition construction section (23) and an ultra-wide overlapped construction section (24) along the length direction of the tunnel main body structure; the construction method of the main body construction section (22), the construction method of the transition construction section (23) and the construction method of the ultra-wide overlapped construction section (24) are the same, and the construction method comprises the following steps:

step one, excavating construction, and constructing a base cushion layer:

after the construction of the supporting structure is finished, excavating layer by layer from top to bottom until reaching the foundation; in the process of excavating layer by layer, after each layer of excavation is finished, horizontal supports are constructed between the two underground diaphragm walls (1), a plurality of horizontal supports constructed layer by layer form a horizontal support structure between the two underground diaphragm walls (1), and then a base cushion layer (9) is constructed;

step two, dividing the cross section of the main body construction section, the cross section of the transition construction section and the cross section of the ultra-wide overlapped construction section into a plurality of construction layers from bottom to top along the excavation direction:

the cross section of the main construction section (22) and the cross section of the transition construction section (23) are identical in structure of a plurality of construction layers, a main line tunnel bottom plate (5-1), a main line tunnel side wall (5-2) and a main line tunnel top plate (5-3) are constructed in a layered mode from bottom to top in the main construction section (22) and the transition construction section (23), a first ramp bottom plate (17-1) and a second ramp bottom plate (18-1) are constructed in the same layer, a first ramp side wall (17-2) and a second ramp side wall (18-2) are constructed in the same layer, and a first ramp top plate (17-3) and a second ramp top plate (18-3) are constructed in the same layer;

the main line tunnel bottom plate (5-1) and the main line tunnel side walls (5-2) in the ultra-wide overlapped construction section (24) are constructed in a layered mode from bottom to top, a first ramp bottom plate (17-1) and a main line tunnel top plate (5-3) in the ultra-wide overlapped construction section (24) are constructed in the same layer, a first ramp side wall (17-2) and a second ramp bottom plate (18-1) in the ultra-wide overlapped construction section (24) are constructed in the same layer, a first ramp top plate (17-3) and a second ramp side wall (18-2) in the ultra-wide overlapped construction section (24) are constructed in the same layer, and a second ramp top plate (18-3) in the ultra-wide overlapped construction section (24) is constructed in a layered mode;

the distance between a first ramp and a second ramp in the main body construction section (22) is a first distance, the distance between the first ramp and the second ramp in the transition construction section (23) is a second distance, the distance between the first ramp and the second ramp in the ultra-wide stacking type construction section (24) is a third distance, wherein the first distance and the third distance are fixed values, the first distance is smaller than the third distance, the value range of the second distance is between the first distance and the third distance, and the value of the second distance is increased progressively along the length direction of the transition construction section (23);

step three, constructing a main body construction section, a transition construction section and an ultra-wide overlapped construction section simultaneously:

and the construction of the main construction section (22), the construction of the transition construction section (23) and the construction of the ultra-wide overlapped construction section (24) are all constructed in sequence from bottom to top according to a plurality of construction layers divided in the step two, and before each layer of construction, the horizontal support in the current construction layer needs to be removed first, and then the construction of the current construction layer is carried out.

2. The construction method of the main body structure of the underpass lake area section tunnel according to claim 1, characterized in that: in the first step, the construction process of the supporting structure comprises the following steps: the construction method comprises the following steps of construction of the diaphragm wall (1), construction of the engineering pile (3) and the lattice column (6), reinforcement of a foundation of the jet grouting pile (4), and pouring of the crown beam (2).

3. The construction method of the main body structure of the underpass lake area section tunnel according to claim 1, characterized in that: in the first step, the horizontal supporting structure comprises N concrete supports (7), M steel supports (8) are parallelly distributed between every two adjacent concrete supports (7), wherein N and M are positive integers.

4. The construction method of the main body structure of the underpass lake area section tunnel according to claim 1, characterized in that: in the third step, the specific construction method for constructing the main construction section (22) and the transition construction section (23) from bottom to top according to the plurality of construction layers divided in the second step comprises the following steps:

step A: the layered construction method of the main line tunnel specifically comprises the following steps:

casting and molding a main line tunnel bottom plate (5-1) on the base cushion layer (9), and then casting and molding a reinforced concrete slab (10); dismantling a horizontal support in a construction area of a side wall (5-2) of the main line tunnel; pouring and molding the side wall (5-2) of the main line tunnel, and constructing a plain concrete backfill layer (11); then, inclined cast supports (12) are erected between the main line tunnel bottom plate (5-1) and the main line tunnel side wall (5-2) and between the reinforced concrete slab (10) and the underground diaphragm wall (1); dismantling horizontal supports in a construction area of a main line tunnel top plate (5-3); casting and molding a main line tunnel top plate (5-3); then, pouring and forming a reinforced concrete beam (14);

and B: cutting off the lattice column:

dismantling the inclined cast support (12) erected in the step A, and constructing a backfill cement soil layer (13); then, cutting off the latticed column (6) to enable a latticed column residual section (6-1) to be arranged in the bottom plate (5-1) of the main line tunnel;

and C: constructing a first ramp and a second ramp, and specifically comprising the following processes:

removing horizontal supports in construction areas of a first ramp cushion layer (15) and a second ramp cushion layer (16), and constructing the first ramp cushion layer (15) and the second ramp cushion layer (16) on the top surfaces of a main line tunnel top plate (5-3) and a reinforced concrete beam (14), wherein the thickness of the second ramp cushion layer (16) is larger than that of the first ramp cushion layer (15); pouring and forming a first ramp bottom plate (17-1) and a second ramp bottom plate (18-1); then, constructing a first backfill solid soil layer (19);

dismantling horizontal supports in construction areas of the first ramp side wall (17-2) and the second ramp side wall (18-2); pouring and forming a first ramp side wall (17-2) and a second ramp side wall (18-2), and erecting inclined cast braces (12) between the first ramp bottom plate (17-1) and the first ramp side wall (17-2) and between the second ramp bottom plate (18-1) and the second ramp side wall (18-2); dismantling horizontal supports in construction areas of a first ramp top plate (17-3) and a second ramp top plate (18-3); casting and molding a first ramp top plate (17-3) and a second ramp top plate (18-3);

step D: constructing a second backfill dense soil layer:

and (3) dismantling a horizontal support in a construction area of the second backfill dense soil layer, dismantling the inclined cast support (12) erected in the step C, constructing the second backfill dense soil layer (20), and enabling the top surface of the second backfill dense soil layer (20) to be flush with the top surface of the crown beam 2.

5. The construction method of the main body structure of the underpass lake area section tunnel according to claim 5, characterized in that: in the step A, before the main line tunnel bottom plate (5-1) is cast, a waterproof layer of the main line tunnel bottom plate (5-1) needs to be constructed on a base cushion layer (9); before the main line tunnel side wall (5-2) is cast and formed, a waterproof layer of the main line tunnel side wall (5-2) needs to be constructed; after the main line tunnel top plate (5-3) is cast and molded, a waterproof layer of the main line tunnel top plate (5-3) needs to be constructed on the top surface of the main line tunnel top plate (5-3).

6. The construction method of the main body structure of the underpass lake area section tunnel according to claim 5, characterized in that: in the step C, before the first ramp bottom plate (17-1) is cast, a waterproof layer of the first ramp bottom plate (17-1) needs to be constructed on the first ramp cushion layer (15); before the second ramp bottom plate (18-1) is cast, a waterproof layer of the second ramp bottom plate (18-1) needs to be constructed on the second ramp cushion layer (16); before the first ramp side wall (17-2) is cast and formed, a waterproof layer of the first ramp side wall (17-2) needs to be constructed, and before the second ramp side wall (18-2) is cast and formed, a waterproof layer of the second ramp side wall (18-2) needs to be constructed; after the first ramp top plate (17-3) and the second ramp top plate (18-3) are cast, a waterproof layer of the first ramp top plate (17-3) needs to be constructed on the top surface of the first ramp top plate (17-3), and a waterproof layer of the second ramp top plate (18-3) needs to be constructed on the top surface of the second ramp top plate (18-3).

7. The construction method of the main body structure of the underpass lake area section tunnel according to claim 1, characterized in that: in the third step, the specific construction method for constructing the ultra-wide overlapped construction section (24) from bottom to top according to the plurality of construction layers divided in the second step comprises the following steps:

step a: the main line tunnel bottom plate and the main line tunnel side wall of the main line tunnel are constructed in a layered mode, and the method specifically comprises the following steps:

casting and molding a main line tunnel bottom plate (5-1) on the base cushion layer (9), and then casting and molding a reinforced concrete slab (10); dismantling the horizontal supports in the construction area of the main line tunnel side wall (5-2), and pouring and forming the main line tunnel side wall (5-2); then, erecting an inclined cast strut (12) between the bottom plate (5-1) of the main line tunnel and the side wall (5-2) of the main line tunnel, and constructing and backfilling a cement soil layer (13);

step b: cutting off lattice columns, constructing a main line tunnel top plate and a first ramp bottom plate on the same layer:

b, dismantling the inclined throwing support (12) erected in the step a; then, cutting off the latticed column (6) to enable a latticed column residual section (6-1) to be arranged in the bottom plate (5-1) of the main line tunnel;

dismantling a horizontal support in a construction area of a main line tunnel top plate (5-3), and pouring and forming the main line tunnel top plate (5-3) and a first ramp bottom plate (17-1); then, constructing a plain concrete backfill layer (11);

step c: constructing a first ramp side wall and a second ramp bottom plate on the same layer:

dismantling horizontal supports in construction areas of the first ramp side wall (17-2) and the second ramp bottom plate (18-1), and pouring and forming the first ramp side wall (17-2) and the second ramp bottom plate (18-1); afterwards, backfilling the liquid concrete layer (21);

step d: constructing a first ramp top plate and a second ramp side wall on the same layer:

dismantling horizontal supports in construction areas of a first ramp top plate (17-3) and a second ramp side wall (18-2); casting and molding a first ramp top plate (17-3) and a second ramp side wall (18-2);

step e: constructing a second ramp top plate and a second backfill dense soil layer:

and (3) removing horizontal supports in construction areas of the second ramp top plate (18-3) and the second backfill dense soil layer (20), pouring and forming the second ramp top plate (18-3), and constructing the second backfill dense soil layer (20), wherein the top surface of the second backfill dense soil layer (20) is flush with the top surface of the crown beam (2).

Technical Field

The invention belongs to the technical field of tunnel construction, and particularly relates to a construction method of a main body structure of an underpass type lake area tunnel.

Background

With the rapid development of urban infrastructure, the increase of urban automobile traffic volume and the gradual improvement of requirements of people on landscape and environment, urban lake bottom tunnels are rapidly constructed and developed on a large scale. At present, the structural form of the large-section tunnel at the bottom of the urban lake basically adopts a rectangular box type frame structure, and the construction method basically adopts an open-cut smooth method as a main method. However, when the underpass type lake area section tunnel is constructed, the average water level of the lake area section is 1.31m, and due to the fact that a soft soil layer with a certain thickness exists on the surface layer of a tunnel foundation pit, large and medium construction machinery and construction personnel are difficult to operate and construct, meanwhile, due to the mucky soil layer, the displacement of a supporting structure is too large, the uplift displacement of the pit bottom is too large, and the settlement displacement of the peripheral earth surface is too large, so that the instability of the foundation pit is easily caused, the construction risk is large, the construction efficiency is low, and the construction safety is poor. Therefore, it is desirable to provide a construction method of a tunnel structure of an underpass lake area section, which can improve construction efficiency.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a construction method of a main body structure of an underpass type lake area section tunnel, which is simple in structure and reasonable in design, can ensure that the lake area section tunnel structure has an accurate extending direction, can greatly shorten the construction period of the lake area section tunnel structure, can form a stable and balanced construction space at the bottom of a lake, and can avoid the problem of foundation pit safety at the bottom of the lake.

In order to solve the technical problems, the invention adopts the technical scheme that: a construction method of a main body structure of a downward-penetrating type lake area section tunnel is characterized by comprising the following steps: the tunnel main body structure is divided into a main body construction section, a transition construction section and an ultra-wide overlapped construction section along the length direction of the tunnel main body structure; the construction method of the main body construction section, the construction method of the transition construction section and the construction method of the ultra-wide overlapped construction section are the same, and the construction method comprises the following steps:

step one, excavating construction, and constructing a base cushion layer:

after the construction of the supporting structure is finished, excavating layer by layer from top to bottom until reaching the foundation; in the process of excavating layer by layer, after each layer of excavation is finished, horizontal supports are constructed between the two underground continuous walls, a plurality of horizontal supports constructed layer by layer form a horizontal support structure between the two underground continuous walls, and then a base cushion layer is constructed;

step two, dividing the cross section of the main body construction section, the cross section of the transition construction section and the cross section of the ultra-wide overlapped construction section into a plurality of construction layers from bottom to top along the excavation direction:

the construction method comprises the following steps that a plurality of construction layer structures of the cross section of a main body construction section and the cross section of a transition construction section are the same, a main line tunnel bottom plate, a main line tunnel side wall and a main line tunnel top plate are constructed from bottom to top in the main body construction section and the transition construction section in a layered mode, a first ramp bottom plate and a second ramp bottom plate are constructed in the same layer, a first ramp side wall and a second ramp side wall are constructed in the same layer, and a first ramp top plate and a second ramp top plate are constructed in the same layer;

the main line tunnel bottom plate and the main line tunnel side wall in the ultra-wide overlapped construction section are constructed in a layered mode from bottom to top, the first ramp bottom plate and the main line tunnel top plate in the ultra-wide overlapped construction section are constructed in the same layer, the first ramp side wall and the second ramp bottom plate in the ultra-wide overlapped construction section are constructed in the same layer, the first ramp top plate and the second ramp side wall in the ultra-wide overlapped construction section are constructed in the same layer, and the second ramp top plate in the ultra-wide overlapped construction section is constructed in a layered mode;

the distance between a first ramp and a second ramp in the main body construction section is a first distance, the distance between the first ramp and the second ramp in the transition construction section is a second distance, and the distance between the first ramp and the second ramp in the ultra-wide stacking type construction section is a third distance, wherein the first distance and the third distance are fixed values, the first distance is smaller than the third distance, the value range of the second distance is between the first distance and the third distance, and the value of the second distance is increased progressively along the length direction of the transition construction section;

step three, constructing a main body construction section, a transition construction section and an ultra-wide overlapped construction section simultaneously:

and constructing the main body construction section, the transition construction section and the ultra-wide overlapped construction section in turn according to the plurality of construction layers divided in the step two from bottom to top, and before each layer of construction, firstly removing the horizontal support in the current construction layer and then constructing the current construction layer.

The construction method of the main body structure of the underpass type lake area tunnel is characterized by comprising the following steps of: in the first step, the construction process of the supporting structure comprises the following steps: the construction of diaphragm wall, the construction of engineering pile and lattice column, the reinforcement of jet grouting pile foundation and the pouring of crown beam.

The construction method of the main body structure of the underpass type lake area tunnel is characterized by comprising the following steps of: in the first step, the horizontal supporting structure comprises N concrete supports, M steel supports are parallelly distributed between every two adjacent concrete supports, wherein N and M are positive integers.

The construction method of the main body structure of the underpass type lake area tunnel is characterized by comprising the following steps of: in the third step, the specific construction method for constructing the main construction section and the transitional construction section from bottom to top according to the plurality of construction layers divided in the second step comprises the following steps:

step A: the layered construction method of the main line tunnel specifically comprises the following steps:

pouring and forming a main line tunnel bottom plate on the base cushion layer, and then pouring and forming a reinforced concrete plate; dismantling a horizontal support in a side wall construction area of the main line tunnel; pouring and molding the side wall of the main line tunnel, and constructing a plain concrete backfill layer; then, inclined cast supports are erected between the main line tunnel bottom plate and the main line tunnel side wall and between the reinforced concrete slab and the underground diaphragm wall; removing a horizontal support in a main line tunnel top plate construction area; pouring and molding a main line tunnel top plate; then, pouring and forming the reinforced concrete beam;

and B: cutting off the lattice column:

b, dismantling the inclined throwing support erected in the step A, and constructing and backfilling a cement soil layer; then, cutting off the lattice column to enable the main line tunnel bottom plate to have a lattice column residual section;

and C: constructing a first ramp and a second ramp, and specifically comprising the following processes:

removing horizontal supports in construction areas of a first ramp cushion layer and a second ramp cushion layer, and constructing the first ramp cushion layer and the second ramp cushion layer on the top surfaces of a main line tunnel top plate and a reinforced concrete beam, wherein the thickness of the second ramp cushion layer is larger than that of the first ramp cushion layer; pouring and forming a first ramp bottom plate and a second ramp bottom plate; then, constructing a first backfill solid soil layer;

dismantling horizontal supports in the construction areas of the first ramp side wall and the second ramp side wall; pouring and molding a first ramp side wall and a second ramp side wall, and erecting inclined throwers between a first ramp bottom plate and the first ramp side wall and between a second ramp bottom plate and the second ramp side wall; dismantling horizontal supports in the construction areas of the top plate of the first ramp and the top plate of the second ramp; pouring and forming a first ramp top plate and a second ramp top plate;

step D: constructing a second backfill dense soil layer:

and D, dismantling a horizontal support in a construction area of the second backfill dense soil layer, dismantling the inclined throw support erected in the step C, and constructing the second backfill dense soil layer, wherein the top surface of the second backfill dense soil layer is flush with the top surface of the crown beam 2.

The construction method of the main body structure of the underpass type lake area tunnel is characterized by comprising the following steps of: in the step A, before the main line tunnel bottom plate is cast, a waterproof layer of the main line tunnel bottom plate needs to be constructed on a base cushion layer; before the main line tunnel side wall is cast and formed, a waterproof layer of the main line tunnel side wall needs to be constructed; after the main line tunnel top plate is cast and formed, a waterproof layer of the main line tunnel top plate needs to be constructed on the top surface of the main line tunnel top plate.

The construction method of the main body structure of the underpass type lake area tunnel is characterized by comprising the following steps of: in the step C, before the first ramp bottom plate is cast, a waterproof layer of the first ramp bottom plate needs to be constructed on the first ramp cushion layer; before the second ramp bottom plate is cast and formed, a waterproof layer of the second ramp bottom plate needs to be constructed on the second ramp cushion layer; before the first ramp side wall is cast and formed, a waterproof layer of the first ramp side wall needs to be constructed, and before the second ramp side wall is cast and formed, a waterproof layer of the second ramp side wall needs to be constructed; after the first ramp top plate and the second ramp top plate are cast, a waterproof layer of the first ramp top plate needs to be constructed on the top surface of the first ramp top plate, and a waterproof layer of the second ramp top plate needs to be constructed on the top surface of the second ramp top plate.

The construction method of the main body structure of the underpass type lake area tunnel is characterized by comprising the following steps of: in the third step, the specific construction method for constructing the ultra-wide overlapped construction section from bottom to top according to the plurality of construction layers divided in the second step comprises the following steps:

step a: the main line tunnel bottom plate and the main line tunnel side wall of the main line tunnel are constructed in a layered mode, and the method specifically comprises the following steps:

pouring and forming a main line tunnel bottom plate on the base cushion layer, and then pouring and forming a reinforced concrete plate; removing the horizontal support in the construction area of the side wall of the main line tunnel, and pouring and forming the side wall of the main line tunnel; then, erecting an inclined throwing support between the bottom plate of the main line tunnel and the side wall of the main line tunnel, and constructing and backfilling a cement soil layer;

step b: cutting off lattice columns, constructing a main line tunnel top plate and a first ramp bottom plate on the same layer:

d, dismantling the inclined throwing support erected in the step a; then, cutting off the lattice column to enable the main line tunnel bottom plate to have a lattice column residual section;

removing a horizontal support in a construction area of a main line tunnel top plate, and pouring and forming the main line tunnel top plate and a first ramp bottom plate; then, constructing a plain concrete backfill layer;

step c: constructing a first ramp side wall and a second ramp bottom plate on the same layer:

removing horizontal supports in the construction areas of the first ramp side wall and the second ramp bottom plate, and pouring and forming the first ramp side wall and the second ramp bottom plate; then, backfilling a liquid concrete layer;

step d: constructing a first ramp top plate and a second ramp side wall on the same layer:

dismantling horizontal supports in the construction areas of the top plate of the first ramp and the side wall of the second ramp; pouring and forming a first ramp top plate and a second ramp side wall;

step e: constructing a second ramp top plate and a second backfill dense soil layer:

and removing the horizontal supports in the construction areas of the second ramp top plate and the second backfill dense soil layer, pouring and forming the second ramp top plate, and constructing the second backfill dense soil layer, wherein the top surface of the second backfill dense soil layer is flush with the top surface of the crown beam.

Compared with the prior art, the invention has the following advantages:

1. the tunnel structure of the lake area section is arranged at the whole lake bottom from the west bank to the east bank of the lake area, the distance between the arrangement position of the tunnel main body structure and the north of the lake area is less than 50m, and an existing pond is arranged between the west bank and the north bank of the lake area, so that when the tunnel main body structure comprises a main body construction section, a transition construction section and an ultra-wide overlapping type construction section which are sequentially arranged from the west bank to the east bank of the lake area, the transition construction section can be used for realizing smooth transition between the main body construction section and the ultra-wide overlapping type construction section, and when the main body construction section and the transition construction section are close to the north bank of the lake area and the existing pond, the ultra-wide overlapping type construction section can be enabled to avoid the north bank of the lake area, and high-quality geographical conditions can be provided for the construction of the ultra-wide overlapping type construction section.

2. In the second step of the invention, the main line tunnel is divided into a main line tunnel bottom plate, main line tunnel side walls and a main line tunnel top plate; the first ramp is only divided into a first ramp bottom plate, a first ramp side wall and a first ramp top plate; the second ramp is only divided into a second ramp bottom plate, a second ramp side wall and a second ramp top plate, and compared with the prior art, the number of layers of the main line tunnel, the first ramp and the second ramp in the vertical direction is reduced, meanwhile, tightness among all layers of forming structures can be guaranteed, convenience in construction can be improved, large-scale mechanical equipment is convenient to use, and construction efficiency is improved.

3. In the third step of the invention, when the main body construction section, the transition construction section and the ultra-wide stacking type construction section are constructed simultaneously, the construction period of the tunnel structure of the lake area section can be greatly shortened, and meanwhile, a stable and balanced construction space can be formed at the lake bottom.

4. The invention has simple structure, reasonable design, low manufacturing cost and convenient popularization and application.

In conclusion, the invention has simple structure and reasonable design, can ensure that the tunnel structure of the lake region section has accurate extension direction, can greatly shorten the construction period of the tunnel structure of the lake region section, can form a stable and balanced construction space at the bottom of the lake, and can avoid the problem of foundation pit safety at the bottom of the lake.

The invention is described in further detail below with reference to the figures and examples.

Drawings

FIG. 1 is a flow chart of the present invention.

FIG. 2 is a layout of a main body construction section, a transitional construction section, and an ultra-wide overlap construction section according to the present invention.

FIG. 3 is a schematic construction section of a main construction section according to the present invention.

FIG. 4 is a schematic construction cross-section of an ultra-wide stacked construction segment according to the present invention.

Fig. 5 is a schematic structural view of excavation construction of a main body construction section of the present invention.

Fig. 6 is a schematic structural diagram of the main line tunnel bottom plate and the main line tunnel side wall in the main body construction section of the present invention.

Fig. 7 is a schematic structural diagram of the first ramp bottom plate and the second ramp bottom plate, and the first ramp side wall and the second ramp side wall in the main body construction section of the present invention.

Description of reference numerals:

1-diaphragm wall; 2-a crown beam; 3, engineering piles;

4-jet grouting pile; 5-1-main line tunnel floor; 5-2-main line tunnel side wall;

5-3-main line tunnel roof; 6-lattice column; 6-1-lattice column residue section;

7, supporting concrete; 8, supporting steel; 9-base cushion layer;

10-reinforced concrete slab; 11-plain concrete backfill layer; 12-inclined throwing support;

13-backfilling a cement soil layer; 14-reinforced concrete beam; 15-first ramp cushion layer;

16-a second ramp cushion layer; 17-1 — first ramp floor; 17-2 — first ramp side wall;

17-3 — first ramp top plate; 18-1 — a second ramp floor; 18-2 — a second ramp side wall;

18-3 — a second ramp top plate; 19-first backfill solid soil layer;

20-backfilling a dense soil layer for the second time; 21-liquid concrete layer;

22-main body construction section; 23-transition construction section;

24-ultra-wide stacked construction sections; 25-west bank of lake area;

26-east bank of lake region; 27-north bank of lake region; 28-existing pond.

Detailed Description

As shown in fig. 1 to 4, in a construction method of a tunnel structure of an underpass lake region section, a main structure of the tunnel is divided into a main construction section 22, a transitional construction section 23 and an ultra-wide overlapping construction section 24 along a length direction of the main structure; the construction method of the main body construction section 22, the construction method of the transition construction section 23 and the construction method of the ultra-wide overlapped construction section 24 are the same, and the construction method comprises the following steps:

step one, excavating construction, and constructing a base cushion layer:

after the construction of the supporting structure is finished, excavating layer by layer from top to bottom until reaching the foundation; in the process of layer-by-layer excavation, horizontal supports are constructed between the two underground diaphragm walls 1 after each layer of excavation is finished, a plurality of horizontal supports constructed layer-by-layer form a horizontal support structure between the two underground diaphragm walls 1, and then a base cushion layer 9 is constructed.

As shown in fig. 2, in this embodiment, since the tunnel structure of the lake region is arranged over the entire bottom of the lake from the west bank 25 to the east bank 26 of the lake region, and the distance between the arrangement position of the tunnel main body structure and the lake area north bank 27 is less than 50m, and an existing pond 28 is arranged between the lake area west bank 25 and the lake area north bank 27, therefore, when the tunnel main body structure comprises a main body construction section 22, a transition construction section 23 and an ultra-wide overlapped type construction section 24 which are sequentially arranged from a west bank 25 to an east bank 26 of a lake region, a smooth transition between the main body construction section 22 and the ultra-wide overlap construction section 24 can be achieved using the transition construction section 23, when the main body construction section 22 and the transition construction section 23 are close to the north bank 27 of the lake and the existing pond 28, the ultra-wide overlapped construction section 24 can avoid the lake north bank 27, and high-quality geographical conditions can be provided for the construction of the ultra-wide overlapped construction section 24.

In the embodiment, in the first step, the excavation depth of each layer is 500 mm; horizontal bearing structure can realize strutting two ground even wall 1, guarantees the security of foundation ditch excavation.

Step two, dividing the cross section of the main body construction section, the cross section of the transition construction section and the cross section of the ultra-wide overlapped construction section into a plurality of construction layers from bottom to top along the excavation direction:

the cross section of the main construction section 22 and the cross section of the transition construction section 23 are identical in structure of a plurality of construction layers, in the main construction section 22 and the transition construction section 23, a main line tunnel bottom plate 5-1, a main line tunnel side wall 5-2 and a main line tunnel top plate 5-3 are constructed in a layering mode from bottom to top, a first ramp bottom plate 17-1 and a second ramp bottom plate 18-1 are constructed in the same layer, a first ramp side wall 17-2 and a second ramp side wall 18-2 are constructed in the same layer, and a first ramp top plate 17-3 and a second ramp top plate 18-3 are constructed in the same layer;

the main line tunnel bottom plate 5-1 and the main line tunnel side walls 5-2 in the ultra-wide overlapped construction section 24 are constructed in a layered mode from bottom to top, the first ramp bottom plate 17-1 and the main line tunnel top plate 5-3 in the ultra-wide overlapped construction section 24 are constructed in the same layer, the first ramp side wall 17-2 and the second ramp bottom plate 18-1 in the ultra-wide overlapped construction section 24 are constructed in the same layer, the first ramp top plate 17-3 and the second ramp side wall 18-2 in the ultra-wide overlapped construction section 24 are constructed in the same layer, and the second ramp top plate 18-3 in the ultra-wide overlapped construction section 24 is constructed in a layered mode;

the distance between the first ramp and the second ramp in the main body construction section 22 is a first distance, the distance between the first ramp and the second ramp in the transition construction section 23 is a second distance, and the distance between the first ramp and the second ramp in the ultra-wide stacking type construction section 24 is a third distance, wherein the first distance and the third distance are fixed values, the first distance is smaller than the third distance, the value range of the second distance is between the first distance and the third distance, and the value of the second distance is increased along the length direction of the transition construction section 23;

in this embodiment, the length of the tunnel in the lake area segment is 2686m, and the top elevation of the tunnel in the lake area segment is lower than-2.93 m. The main body construction section 22, the transition construction section 23 and the ultra-wide overlapped construction section 24 are all converging sections of a main line tunnel, a first ramp and a second ramp, the main line tunnel is in a structural type on a two-hole one-pipe gallery, the net width of a single hole of the main line tunnel is 13.1m, and the net height of the single hole of the main line tunnel is 6.0 m; the clear width of the middle pipe gallery is 1.8m, and the clear height is 6.0 m; the clear width and the clear height of the first ramp and the second ramp are both 9.1m and 6.0m respectively.

In the embodiment, in the main body construction section 22 and the transition construction section 23, the first ramp bottom plate 17-1 and the second ramp bottom plate 18-1 are both located above the main line tunnel top plate 5-3, and the first distance is 17.5 m; the bottom surface of the first ramp bottom plate 17-1 of the ultra-wide overlapped construction section 24 is lower than the top surface of the main line tunnel top plate 5-3, and the third distance is 29.5 m; the range of the second distance is 17.5m to 29.5m, and the size of the second distance increases progressively along the length direction of the transition construction section 23.

As shown in fig. 3 and 4, in the second step of the present embodiment, the main line tunnel is only divided into a main line tunnel bottom plate 5-1, main line tunnel side walls 5-2, and a main line tunnel top plate 5-3; the first ramp is only divided into a first ramp bottom plate 17-1, a first ramp side wall 17-2 and a first ramp top plate 17-3; the second ramp is only divided into a second ramp bottom plate 18-1, a second ramp side wall 18-2 and a second ramp top plate 18-3, compared with the prior art, the number of layers of the main line tunnel, the first ramp and the second ramp in the vertical direction is reduced, meanwhile, the tightness of each layer of forming structure can be guaranteed, the convenience of construction can be improved, large-scale mechanical equipment is convenient to use, and the construction efficiency is improved.

Step three, constructing a main body construction section, a transition construction section and an ultra-wide overlapped construction section simultaneously:

the construction of the main body construction section 22, the construction of the transition construction section 23 and the construction of the ultra-wide overlapped construction section 24 are all constructed in sequence from bottom to top according to the plurality of construction layers divided in the step two, and before each layer of construction, the horizontal support in the current construction layer needs to be removed, and then the construction of the current construction layer is carried out.

In this embodiment, by constructing the main construction section 22, the transitional construction section 23, and the ultra-wide overlapping construction section 24 simultaneously, not only the construction period of the tunnel main structure can be greatly shortened, but also a stable and balanced construction space can be formed at the lake bottom, and compared with the sequential independent construction of the main construction section 22, the transitional construction section 23, and the ultra-wide overlapping construction section 24, the problem of foundation pit safety at the lake bottom can be avoided.

As shown in fig. 5, 6, and 7, in this embodiment, the first interval of the main construction section, the second interval of the transitional construction section, and the third interval of the ultra-wide overlapped construction section are determined by construction lofting, and the horizontal supports located in the current construction layer need to be removed before each layer of construction, so that it can be avoided that the horizontal supports located in the current construction layer occupy the construction space, which causes a construction process interruption.

In this embodiment, in the first step, the construction process of the supporting structure includes: the construction of the diaphragm wall 1, the construction of the engineering piles 3 and the lattice columns 6, the reinforcement of the foundation of the jet grouting piles 4 and the pouring of the crown beam 2.

In this embodiment, the number of the engineering piles 3 of the transition construction section 23 is greater than the number of the engineering piles 3 of the main body construction section 22, the number of the engineering piles 3 of the ultra-wide overlap type construction section is greater than the number of the engineering piles 3 of the transition construction section 23, the number of the lattice columns 6 of the transition construction section 23 is greater than the number of the lattice columns 6 of the main body construction section 22, and the number of the lattice columns 6 of the ultra-wide overlap type construction section is greater than the number of the lattice columns 6 of the transition construction section 23, so that the bearing capacity of the supporting structure on the main line tunnel, the first ramp and the second ramp can be ensured.

In this embodiment, in the first step, the horizontal support structure includes N concrete supports 7, and M steel supports 8 are arranged in parallel between two adjacent concrete supports 7, where N and M are positive integers.

In this embodiment, a horizontal bearing structure is constituteed jointly to N concrete support 7 and M steel shotcrete 8, and concrete support 7 has the advantage that intensity is high, stability is good, and steel shotcrete 8 has the advantage of being convenient for demolish, consequently, when laying M steel shotcrete 8 between two adjacent concrete support 7 in parallel, not only can improve horizontal bearing structure's stability, can improve the convenience of horizontal bearing structure construction simultaneously.

In this embodiment, in step three, the specific construction method for constructing the main construction section 22 and the transitional construction section 23 from bottom to top according to the plurality of construction layers divided in step two includes:

step A: the layered construction method of the main line tunnel specifically comprises the following steps:

casting and forming a main line tunnel bottom plate 5-1 on the base cushion layer 9, and then casting and forming a reinforced concrete slab 10; dismantling a horizontal support in a construction area of a main line tunnel side wall 5-2; casting and molding the side wall 5-2 of the main line tunnel, and constructing a plain concrete backfill layer 11; then, inclined cast supports 12 are erected between the bottom plate 5-1 of the main line tunnel and the side wall 5-2 of the main line tunnel and between the reinforced concrete plate 10 and the underground diaphragm wall 1; dismantling a horizontal support in a construction area of a main line tunnel top plate 5-3; casting and molding a main line tunnel top plate 5-3; then, the reinforced concrete beam 14 is cast and formed;

and B: cutting off the lattice column:

dismantling the inclined cast support 12 erected in the step A, and constructing a backfill cement soil layer 13; then, cutting off the lattice column 6 to enable a lattice column residual section 6-1 to be arranged in the bottom plate 5-1 of the main line tunnel;

in the embodiment, after the backfilled cement soil layer 13 is constructed, the reinforced concrete slab 10, the constructed plain concrete backfilling layer 11, the backfilled cement soil layer 13 and the reinforced concrete beam 14 form a supporting mechanism surrounding the periphery of the main line tunnel, after the supporting mechanism is formed, the lattice column 6 is cut off, so that the main line tunnel bottom plate 5-1 is internally provided with the lattice column residual section 6-1, and the lattice column residual section 6-1, the base cushion layer 9 and the main line tunnel bottom plate 5-1 are connected into a whole, which is beneficial to enhancing the stability of the main line tunnel bottom plate 5-1 in the vertical direction.

And C: constructing a first ramp and a second ramp, and specifically comprising the following processes:

dismantling horizontal supports in construction areas of a first ramp cushion layer 15 and a second ramp cushion layer 16, and constructing the first ramp cushion layer 15 and the second ramp cushion layer 16 on the top surfaces of the main line tunnel top plate 5-3 and the reinforced concrete beam 14, wherein the thickness of the second ramp cushion layer 16 is larger than that of the first ramp cushion layer 15; casting and forming a first ramp bottom plate 17-1 and a second ramp bottom plate 18-1; then, constructing a first backfill solid soil layer 19;

dismantling horizontal supports in construction areas of the first ramp side wall 17-2 and the second ramp side wall 18-2; casting and forming a first ramp side wall 17-2 and a second ramp side wall 18-2, and erecting inclined cast braces 12 between a first ramp bottom plate 17-1 and the first ramp side wall 17-2 and between a second ramp bottom plate 18-1 and the second ramp side wall 18-2; dismantling horizontal supports in construction areas of a first ramp top plate 17-3 and a second ramp top plate 18-3; casting and forming a first ramp top plate 17-3 and a second ramp top plate 18-3;

step D: constructing a second backfill dense soil layer:

and (3) dismantling the horizontal support in the construction area of the second backfill dense soil layer, dismantling the inclined cast support 12 erected in the step C, and constructing a second backfill dense soil layer 20, wherein the top surface of the second backfill dense soil layer 20 is flush with the top surface of the crown beam 2.

In this embodiment, in the step a, before the main line tunnel bottom plate 5-1 is cast, a waterproof layer of the main line tunnel bottom plate 5-1 needs to be constructed on the base cushion layer 9; before the main line tunnel side wall 5-2 is cast and formed, a waterproof layer of the main line tunnel side wall 5-2 needs to be constructed; after the main line tunnel top plate 5-3 is cast, a waterproof layer of the main line tunnel top plate 5-3 needs to be constructed on the top surface of the main line tunnel top plate 5-3.

In this embodiment, the waterproof layer of the main line tunnel bottom plate 5-1, the waterproof layer of the main line tunnel side wall 5-2, and the waterproof layer of the main line tunnel top plate 5-3 together form a reliable waterproof layer structure on the outer side of the main line tunnel, and for the underpass type lake area section tunnel structure, the construction quality of the waterproof layer structure must be improved, and the waterproof effect of the waterproof layer structure is ensured.

In this embodiment, in step C, before the first ramp bottom plate 17-1 is cast, a waterproof layer of the first ramp bottom plate 17-1 needs to be constructed on the first ramp cushion layer 15; before the second ramp bottom plate 18-1 is cast, a waterproof layer of the second ramp bottom plate 18-1 needs to be constructed on the second ramp cushion layer 16; before the first ramp side wall 17-2 is cast and formed, a waterproof layer of the first ramp side wall 17-2 needs to be constructed, and before the second ramp side wall 18-2 is cast and formed, a waterproof layer of the second ramp side wall 18-2 needs to be constructed; after the first ramp top plate 17-3 and the second ramp top plate 18-3 are cast, a waterproof layer of the first ramp top plate 17-3 needs to be constructed on the top surface of the first ramp top plate 17-3, and a waterproof layer of the second ramp top plate 18-3 needs to be constructed on the top surface of the second ramp top plate 18-3.

In the third step, the specific construction method for constructing the ultra-wide overlapped construction section 24 from bottom to top according to the plurality of construction layers divided in the second step comprises the following steps:

step a: the main line tunnel bottom plate and the main line tunnel side wall of the main line tunnel are constructed in a layered mode, and the method specifically comprises the following steps:

casting and forming a main line tunnel bottom plate 5-1 on the base cushion layer 9, and then casting and forming a reinforced concrete slab 10; dismantling the horizontal support in the construction area of the main line tunnel side wall 5-2, and pouring and forming the main line tunnel side wall 5-2; then, erecting an inclined cast strut 12 between the bottom plate 5-1 of the main line tunnel and the side wall 5-2 of the main line tunnel, and constructing and backfilling a cement soil layer 13;

step b: cutting off lattice columns, constructing a main line tunnel top plate and a first ramp bottom plate on the same layer:

dismantling the inclined throwing support 12 erected in the step a; then, cutting off the lattice column 6 to enable a lattice column residual section 6-1 to be arranged in the bottom plate 5-1 of the main line tunnel;

dismantling a horizontal support in a construction area of a main line tunnel top plate 5-3, and pouring and forming the main line tunnel top plate 5-3 and a first ramp bottom plate 17-1; then, constructing a plain concrete backfill layer 11;

in this embodiment, since the horizontal distance between the first ramp and the second ramp of the ultra-wide overlap type construction section 24 is 29.5m, and the bottom surface of the first ramp bottom plate 17-1 of the ultra-wide overlap type construction section 24 is lower than the top surface of the main line tunnel top plate 5-3, the main line tunnel top plate 5-3 and the first ramp bottom plate 17-1 need to be constructed on the same layer, so that the main line tunnel top plate 5-3 and the first ramp bottom plate 17-1 are integrally formed, after the pouring forming of the main line tunnel top plate 5-3 and the first ramp bottom plate 17-1 is completed, the plain concrete backfill layer 11 must be constructed, the structural balance in the foundation pit is maintained by using the plain concrete backfill layer 11 and the backfill cement layer 13, and the construction stability and safety are ensured.

Step c: constructing a first ramp side wall and a second ramp bottom plate on the same layer:

dismantling horizontal supports in construction areas of the first ramp side wall 17-2 and the second ramp bottom plate 18-1, and pouring and forming the first ramp side wall 17-2 and the second ramp bottom plate 18-1; then, backfilling the liquid concrete layer 21;

step d: constructing a first ramp top plate and a second ramp side wall on the same layer:

dismantling horizontal supports in construction areas of a first ramp top plate 17-3 and a second ramp side wall 18-2; casting and molding a first ramp top plate 17-3 and a second ramp side wall 18-2,

step e: constructing a second ramp top plate and a second backfill dense soil layer:

and (3) removing the horizontal supports in the construction areas of the second ramp top plate 18-3 and the second backfill dense soil layer 20, pouring and forming the second ramp top plate 18-3, and constructing the second backfill dense soil layer 20, wherein the top surface of the second backfill dense soil layer 20 is flush with the top surface of the crown beam 2.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.