阅读说明：本技术 一种地下隧道小断面至大断面的扩挖方法 (Underground tunnel small-section to large-section expanding excavation method ) 是由 彭晨 张哲强 刘亮 张美琴 彭柳松 张金伟 李晓英 柳晔 吕杰 王齐 秦威风 于 2021-08-09 设计创作，主要内容包括：本发明涉及一种地下隧道小断面至大断面的扩挖方法,包括以下施工步骤：S1,依次施工构建大型地下隧道所需的多个平行布置的先行导洞,相邻先行导洞之间预留一定的开挖间距；S2,在相邻先行导洞之间施工至少一道分别与两个先行导洞相连接的横向体系,所述横向体系的两侧端部分别设置端锚结构；S3,开挖两个相邻先行导洞之间需要扩挖的部分,将小断面隧道扩挖至大断面隧道。本发明所提供的通过在相邻先行导洞之间施工横向体系,然后在横向体系下进行导洞扩挖的地下隧道小断面至大断面的扩挖方法,可以有效解决现有小断面扩挖至大断面时所存在的风险大、造价高、工期长、施工难度大、地表沉降大等问题。(The invention relates to an expanding excavation method for an underground tunnel from a small section to a large section, which comprises the following construction steps: s1, sequentially constructing a plurality of parallel-arranged pilot tunnels required by constructing the large underground tunnel, and reserving a certain excavation space between adjacent pilot tunnels; s2, constructing at least one transverse system connected with two pilot tunnels respectively between adjacent pilot tunnels, wherein end anchor structures are arranged at two side ends of the transverse system respectively; and S3, excavating the part needing to be expanded and excavated between two adjacent leading tunnels, and expanding and excavating the small-section tunnel to the large-section tunnel. The enlarging and digging method of the underground tunnel from the small section to the large section, which is provided by the invention, can effectively solve the problems of large risk, high cost, long construction period, large construction difficulty, large surface settlement and the like when the existing enlarging and digging of the small section to the large section by constructing the transverse system between the adjacent leading holes and then carrying out the enlarging and digging of the leading holes under the transverse system.)

1. The expanding excavation method for the underground tunnel from the small section to the large section is characterized by comprising the following construction steps of:

s1, sequentially constructing a plurality of parallel-arranged pilot tunnels required by constructing the large underground tunnel, and reserving excavation intervals between adjacent pilot tunnels;

s2, constructing at least one transverse system connected with two pilot tunnels respectively between adjacent pilot tunnels, wherein end anchor structures are arranged at two side ends of the transverse system respectively;

and S3, excavating the part needing to be expanded and excavated between two adjacent leading holes, and expanding and excavating the small end face tunnel to the large section tunnel.

2. The method for enlarging and excavating a small cross section to a large cross section of an underground tunnel according to claim 1, wherein in step S2, the lateral systems are respectively connected to primary support structures of two adjacent pilot tunnels.

3. The expanding excavation method of small section to large section of underground tunnel according to claim 2, wherein in step S3, before expanding excavation of soil between two adjacent leading tunnels, an expanding excavation portion primary support structure is constructed, and the expanding excavation portion primary support structure is located below the transverse system and connected with the primary support structures of the two leading tunnels.

4. The method for enlarging a small cross section to a large cross section of an underground tunnel according to claim 1, wherein in step S2, a preliminary supporting structure of the enlarging portion in the pilot tunnel and an upper backfill layer are respectively constructed in two adjacent pilot tunnels, and both side ends of the lateral system are respectively connected to the upper backfill layer in the two pilot tunnels in an anchoring manner.

5. The method for enlarging a small-to-large-section underground tunnel according to claim 1, wherein in step S2, an enlarged excavation portion primary support structure in a pilot tunnel and an upper backfill layer are constructed in one of two adjacent pilot tunnels, one end of the transverse system is connected to the upper backfill layer by anchoring, and the other end of the transverse system is connected to the primary support structure of the pilot tunnel without constructing the upper backfill layer.

6. The enlarging excavation method of the small section to the large section of the underground tunnel according to claim 4 or 5, wherein in step S3, before enlarging excavation of the soil body between the adjacent leading tunnels, the preliminary bracing structure of the enlarging excavation part is constructed above or below the transverse system.

7. The method for enlarging and excavating a small section to a large section of an underground tunnel according to claim 1, wherein in step S2, the transverse system is one or more combinations of grouting pipes, anchor rods, anchor cables or tie rods.

8. The method for enlarging and excavating a small section to a large section of an underground tunnel according to claim 7, wherein the end anchor structure is a reinforced concrete wale, a profiled steel wale or a steel plate at step S2.

Technical Field

The invention relates to the field of underground engineering, in particular to an expanding excavation method for an underground tunnel from a small section to a large section, which can effectively reduce construction risks, save construction cost and avoid overlarge ground settlement.

Background

Along with the rapid development of society, the development of underground space is emphasized, but most of development positions are located below ground roads, and underground tunnels need to be constructed by adopting a subsurface excavation method due to the restriction of factors such as traffic guidance and improvement. However, when the large-section underground excavation method is adopted for construction under the road, the problems of high risk, long construction period, high construction cost and the like exist. When the traditional hole-column method and the hole-pile method are adopted for construction, a side pile structure needs to be constructed, the construction cost is high, and the construction period is long; although the conventional subsection excavation method is relatively low in manufacturing cost, the ground settlement is easily caused to be overlarge in the construction process, and even the risk of causing pipeline burst and the like exists. Therefore, the traditional underground tunnel underground excavation construction method has the defects of strong limitation, large risk and high construction cost.

Disclosure of Invention

Based on the problems of high risk, high manufacturing cost, long construction period, high construction difficulty, large surface settlement and the like existing in the process of enlarging and excavating a large section through a small section when the underground tunnel is constructed by the traditional large-section underground excavation method, the invention provides an enlarging and excavating method from the small section to the large section of the underground tunnel, which is used for constructing a transverse system between adjacent leading pilot tunnels and then carrying out pilot tunnel enlarging and excavating under the transverse system.

The technical scheme adopted by the invention for solving the technical problems is as follows: an expanding excavation method for small cross sections to large cross sections of underground tunnels specifically comprises the following construction steps:

s1, sequentially constructing a plurality of parallel-arranged pilot tunnels required by constructing the large underground tunnel, and reserving a certain excavation space between adjacent pilot tunnels;

s2, constructing at least one transverse system connected with two pilot tunnels respectively between adjacent pilot tunnels, wherein end anchor structures are arranged at two side ends of the transverse system respectively;

and S3, excavating the part needing to be expanded and excavated between two adjacent leading holes, and expanding and excavating the small end face tunnel to the large section tunnel.

Preferably, in step S2, the lateral systems are connected to the primary support structures of two adjacent leading holes respectively.

Preferably, in step S3, before the soil body between the two leading holes is enlarged, an enlarged excavation portion primary support structure is constructed, and the enlarged excavation portion primary support structure is located below the transverse system and connected to the primary support structures of the two leading holes.

Preferably, in step S2, an enlarged excavation portion primary support structure and an upper backfill layer in the pilot tunnel are respectively constructed in two adjacent pilot tunnels, and both side end portions of the lateral system are respectively connected to the upper backfill layer in the two pilot tunnels by anchoring.

Preferably, in step S2, an enlarged pilot hole primary support structure and an upper backfill layer are formed in one of the adjacent pilot holes, and one end of the transverse system is connected to the upper backfill layer by anchoring and the other end is connected to the pilot hole primary support structure on which the upper backfill layer is not formed.

Preferably, in step S3, before the soil body between adjacent leading holes is enlarged, the enlarged and excavated primary support structure is constructed above or below the transverse system.

Further, in step S2, the transverse system is one or more combinations of grouting pipes, anchor rods, anchor cables, or tie rods.

Further, the end anchor structure is a reinforced concrete waist rail, a profile steel waist rail or a steel plate.

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

1. in the underground tunnel underground excavation method construction process, when a small section is expanded and excavated to a large section, side piles need to be constructed by adopting the traditional hole-column method and the traditional hole-pile method, so that the construction cost is higher, the construction period is longer, and the ground settlement can be well controlled; the method of excavating the side tunnel method, the middle tunnel method and the like in parts can cause overlarge ground settlement and great influence on surrounding environments such as buildings (structures) of underground pipelines and the like, and in the construction of an underground multi-layer structure, a temporary inverted arch needs to be removed when a secondary lining is poured, so that the structure is lack of support in the horizontal direction, and the construction risk is increased; on the basis of integrating the advantages of the traditional construction method, the invention replaces the advanced support or primary support of the expanded excavation part by constructing the transverse system between the adjacent pilot tunnels, thereby saving the construction period of expanded excavation, and simultaneously, the invention can limit the trend of increasing the horizontal clear distance between the adjacent pilot tunnels by adopting a proper connection mode through the transverse system and the pilot tunnels, restrict the horizontal displacement of the two lining arches of the pilot tunnels after expanded excavation, achieve the horizontal deformation of a restriction structure, further reduce the settlement of the arch crown, and finally reduce the settlement of the ground surface above the arch and the settlement of other buildings (structures); and the structural deformation can be flexibly controlled by setting a prestress mode or a later-stage prestress supplementing mode, and the reinforcement ratio is properly reduced.

2. According to the expanding excavation method, the construction process of constructing the underground tunnel by the existing large-section underground excavation method is improved, so that the stress conversion is completed, and the purposes of saving the construction cost and reducing the construction risk are achieved; compared with the traditional underground excavation method, the method can be applied to various large-scale underground excavation methods according to needs, is particularly suitable for asymmetric, multi-span and multilayer tunnel structures, and has wider application range.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a lateral system connected to primary support structures of two adjacent pilot holes in embodiment 1 of the present invention.

Fig. 2 is a schematic structural diagram of a transverse system connected with two pilot tunnels under the working condition of a primary support structure of a construction expanded excavation portion in embodiment 2 of the present invention.

Fig. 3 is a schematic structural view of the anchoring connection between the lateral system and the upper backfill layers in the two pilot holes according to embodiment 3 of the present invention.

Fig. 4 is a schematic structural diagram of an embodiment 4 of the present invention in which one end of the transverse system is connected to the upper backfill layer by anchoring, and the other end is connected to the pilot hole primary support structure of the upper backfill layer that is not constructed.

FIG. 5 is a schematic structural view of example 3, in which a lateral system is disposed below a primary support structure of an enlarged and dug portion.

Fig. 6 and 7 are schematic views of end anchor structures according to embodiments of the present invention.

Description of reference numerals: 1. a first leading hole; 2. a second leading hole; 3. expanding and digging part of the primary support structure; 4. an enlarged excavation portion; 5. a transverse system; 6. expanding and digging part of primary support structure in the guide hole; 7. an end anchor structure; 8. an upper backfill layer; 9. a reinforced concrete wale; 10. a profiled steel wale; 11. an anchorage device; 12. anchoring ribs; 13. anchorage device steel pedestal.

Detailed Description

The present invention will be described in further detail with reference to examples, which are illustrative of the present invention and are not to be construed as being limited thereto.

Example 1: as shown in FIG. 1, the expanding excavation method for the small section to the large section of the underground tunnel specifically comprises the following construction steps:

s1, sequentially constructing a plurality of parallel-arranged pilot tunnels required by constructing the large underground tunnel, and reserving a certain excavation space between adjacent pilot tunnels;

wherein, the arch part primary support advance support of the pilot tunnel needs to be arranged in advance before construction, and advance support measures are reasonably arranged according to stratum characteristics and engineering characteristics;

s2, constructing at least one transverse system 5 connected to the primary support structure of two pilot tunnels (such as the first pilot tunnel 1 and the second pilot tunnel 2 shown in fig. 1) between two adjacent pilot tunnels, wherein the two side ends of the transverse system 5 are respectively provided with an end anchor structure 7;

and S3, excavating a part 4 needing to be expanded and excavated between two adjacent leading holes, and expanding and excavating the small end face tunnel to the large section tunnel.

Example 2: as shown in fig. 2, a difference of the method for enlarging excavation from a small cross section to a large cross section of an underground tunnel from example 1 is that, in step S3, before enlarging excavation of a soil body between two leading holes (a first leading hole 1 and a second leading hole 2), an enlarged excavation part primary support structure 3 needs to be constructed to further ensure safety of enlarging excavation. Wherein, the primary support structure 3 of the expanded excavation part is positioned below the transverse system 5 and is connected with the primary support structures of the two leading holes.

Example 3: as shown in fig. 3, the expanding excavation method for the underground tunnel from the small section to the large section specifically comprises the following construction steps:

s1, sequentially constructing a plurality of parallel-arranged pilot tunnels required by constructing the large underground tunnel, and reserving a certain excavation space between adjacent pilot tunnels;

wherein, the arch part primary support advance support of the pilot tunnel needs to be arranged in advance before construction, and advance support measures are reasonably arranged according to stratum characteristics and engineering characteristics;

s2, constructing a pilot hole internal expanded and excavated primary support structure 6 and an upper backfill layer 8 in two adjacent pilot holes, such as a first pilot hole 1 and a second pilot hole 2 shown in fig. 3, respectively, constructing at least one transverse system 5 between the two pilot holes, which is anchored and connected to the two upper backfill layers 8, respectively, and arranging end anchor structures 7 at two side ends of the transverse system 5, respectively;

s3, constructing a primary support structure 3 of the expanding excavation part between two leading holes, excavating a part 4 needing expanding excavation between two adjacent leading holes, and expanding and excavating the small end face tunnel to the large section tunnel. Wherein, the expanded and dug part primary support structure 3 can be arranged below the transverse system 5, as shown in fig. 3; the enlarged and excavated portion primary support structure 3 may also be disposed above the lateral system 5, as shown in fig. 5.

Example 4: as shown in fig. 4, a method for enlarging and excavating an underground tunnel from a small cross section to a large cross section is different from that of embodiment 3 in that, in step S2, an enlarged and excavated portion of a primary support structure 6 and an upper backfill layer 8 in a pilot hole are constructed only in one pilot hole (e.g., in the second pilot hole 2) of two adjacent pilot holes, and at least one transverse system 5 anchored and connected to the primary support structure of the upper backfill layer 8 and the first pilot hole 1 is constructed between the two pilot holes.

Specifically, in the embodiments 1 to 4, the transverse system 5 is a combination of a grouting pipe, an anchor rod, an anchor cable, a pull rod, or the like, and may be connected to the backfill layer above the primary support structure of the pilot tunnel or the expanded and excavated portion of the primary support structure in the pilot tunnel by selecting a suitable manner according to needs during construction, the anchor rod or the anchor cable may be properly adjusted in angle, and extend into the two liners to provide a post-tensioning condition after the two liners are completely constructed, which is not shown in the drawing. Further, as shown in fig. 6 and 7, the anchor structures 7 at both sides of the transverse system 5 can take various forms, such as: arranging a reinforced concrete wale 9 or a steel plate at the end part of the transverse system 5; or the end part of the transverse system 5 is provided with a section steel waist beam 10, two sides of the section steel waist beam 10 are respectively connected with an anchorage device 11 and an anchorage device steel pedestal 13, one side of the anchorage device steel pedestal 13 is provided with an anchor bar 12, and the anchor bar 12 is connected with the primary support structure of the advanced pilot tunnel or connected with an upper backfill layer in the advanced pilot tunnel.

The construction method of the embodiments 1 to 4 of the invention is particularly suitable for the construction process of single-span or multi-span and single-layer or multi-layer tunnel structures, compared with the existing large-section underground excavation construction method, the construction process is improved, the risk of expanding and excavating small sections to large sections during the construction of the large-section underground excavation method can be effectively reduced, the construction cost and the construction period are saved, and meanwhile, the vertical deformation of the tunnel structure and the corresponding settlement of the ground surface of the building (structure) above can be effectively controlled, so that a more ideal solution is provided for the large-scale underground space development which may be faced in the future.

In addition, it should be noted that the specific embodiments described in the present specification may differ in the shape of the components, the names of the components, and the like. All equivalent or simple changes of the structure, the characteristics and the principle of the invention which are described in the patent conception of the invention are included in the protection scope of the patent of the invention. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the scope of the invention as defined in the accompanying claims.