Tunnel full-section excavation support forming construction method with inverted arch

Abstract

The invention discloses a tunnel full-section excavation support forming construction method with an inverted arch. The method comprises the following steps that construction preparation is conducted; an arch frame is manufactured, the arch frame comprises an arch wall section and an inverted arch section, and the arch wall section and the inverted arch section are spliced and connected; performing drilling construction on the tunnel face to obtain blast holes, installing detonators in the blast holes, and performing blasting to obtain a tunnel section; trimming the contour line of the tunnel section; mounting the arch frame to the tunnel section, connecting a reinforcing mesh to the arch frame, and hanging the reinforcing mesh; wet-spraying concrete to the inverted arch section and the arch wall section to form a closed support ring; and the tunnel section is monitored and measured. According to the construction method, the problems that in the prior art, inverted arch construction often needs to be independently operated after an arch wall is closed, the opening time is long, the construction difficulty is large, a structure of'the arch wall is closed but the inverted arch is not closed 'is formed, circumferential stress is incomplete, and the overall stability is poor are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction, and in particular to a tunnel full-section excavation, support and forming construction method with an inverted arch. Background Art

[0002] Tunnel support is a crucial means of ensuring safe construction of underground projects, and its importance is becoming increasingly prominent, especially in weak surrounding rock geological conditions. Currently, commonly used primary support methods include steel arches, anchors, and shotcrete, with partial excavation and inverted arch lagging support being the primary methods. However, in soft rock sections with high ground stress and large deformation, the surrounding rock strength is low, deformation is large, and the duration is long. This often leads to significant deformation before the primary support structure is closed, resulting in insufficient rigidity of the support system, leading to serious problems such as arch instability, cracking of the shotcrete layer, and inverted arch intrusion, which directly impacts project quality and construction safety. In particular, in deep, soft rock tunnels, the surrounding rock often undergoes large, time-dependent deformation or rheological failure due to stress redistribution, rock creep, and hydrothermal chemical reactions. This results in repeated construction progress and frequent support failures with traditional partial excavation methods, requiring multiple arch replacements and reinforcements, an extremely long construction period, and significantly increased safety risks. Furthermore, existing techniques often require the construction of an inverted arch to be completed separately after the arch wall is closed. This results in a long opening time and high construction difficulty, resulting in a structure where the arch wall is closed but the inverted arch is not. This leads to incomplete circumferential stress distribution and poor overall stability. Therefore, a new technical solution is urgently needed to address at least one of these technical issues. Summary of the Invention

[0003] In view of the above-mentioned deficiencies, one object of the present invention is to provide a method for excavation, support and forming construction of a full-section tunnel with an inverted arch, so as to solve the problem that the inverted arch construction in the prior art often needs to be carried out separately after the arch wall is closed, the opening time is long, the construction is difficult, and a "arch wall is closed but the inverted arch is not closed" structure is formed, resulting in incomplete circumferential force and poor overall stability.

[0004] In order to achieve the above technical objectives and meet the above technical requirements, the technical solution adopted by the present invention is: A tunnel full-section excavation, support and forming construction method with an inverted arch, characterized by comprising the following steps: Construction preparation; Producing an arch frame, the arch frame comprising an arch wall section and an inverted arch section, and assembling and connecting the arch wall section and the inverted arch section; Drill holes on the tunnel face to obtain blasting holes, install detonators in the blasting holes, and blast to obtain the tunnel section; trimming the contour line of the tunnel section; Installing the arch frame to the tunnel section, connecting the steel mesh to the arch frame and hanging the mesh; Wet-spray concrete on the inverted arch section and the arch wall section to form a closed support ring; Monitoring measurements are made on the tunnel section.

[0005] As a preferred technical solution, the arch wall section comprises a vault unit, a first arc edge arch unit and a second arc edge arch unit connected to both ends of the vault unit respectively, a first linear edge arch unit connected to the lower end of the first arc edge arch unit, and a second linear edge arch unit connected to the second linear edge arch unit, and the inverted arch section comprises a plurality of inverted arch units, and both ends of the inverted arch section are connected to the first linear edge arch unit and the second linear edge arch unit respectively.

[0006] As a preferred technical solution, the inverted arch section comprises a first inverted arch unit, a second inverted arch unit and a third inverted arch unit connected in sequence, the first inverted arch unit is connected to the first linear edge arch unit, and the third inverted arch unit is connected to the second linear edge arch unit.

[0007] As a preferred technical solution, a milling machine and a hawk hook are used to trim the contour line of the tunnel section.

[0008] As a preferred technical solution, the blasting holes are arranged in a layered and segmented manner.

[0009] As a preferred technical solution, when trimming the contour line of the tunnel section, the tunnel section cannot be under-excavated within 1m above the springing, and other parts are allowed to be under-excavated by not more than 0.1m per 1m. 2 not more than 0.1m 2 .

[0010] As a preferred technical solution, the wet sprayed concrete adopts early high-strength wet sprayed concrete, the 8h strength is not less than 10MPa, the 24h strength is not less than 15MPa, and the surface flatness of the wet sprayed concrete is not more than 1 / 2.

[0011] As a preferred technical solution, when installing the arch frame, the arch frame is positioned on the trimmed tunnel section, a locking foot bar is welded at the lower end of the arch wall section, a locking foot hole is constructed below the locking foot bar, and the locking foot bar is inserted into the locking foot hole.

[0012] As a preferred technical solution, the detonator adopts an electrically controlled electronic detonator.

[0013] As a preferred technical solution, the construction preparation step comprises arranging a vault sinking, a peripheral convergence, and an inverted arch displacement monitoring point.

[0014] Compared with the traditional technical solution, the beneficial effects of the present application are: 1) The present application realizes the synchronous development of inverted arch and arch wall support construction, breaks the structure closure lag and incomplete support caused by the lag construction of inverted arch in the traditional construction method, forms a full-section and integral primary support structure, and significantly improves the stability of the support structure; 2) Through the arch unit prefabrication and construction site assembly process, the construction efficiency and assembly accuracy are improved, various cross section size changes are adapted, the technical problems of on-site forming arch processing, large error and weak connection are solved, and the structural reliability is ensured; 3) The contour line of the tunnel cross section is trimmed, the disturbance degree of the inverted arch area is significantly reduced, and the integrity of the tunnel bottom foundation and the adhesion quality of the subsequent supporting layer are ensured; 4) Form a closed supporting ring at one time, effectively resist the large deformation load of surrounding rock, and avoid arch instability and deformation out of limits caused by long opening time of primary support; 5) The risk control ability and safety guarantee level of the whole construction process are improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The flow chart of the construction method provided for an embodiment of the present application; Figure 2 The structural schematic diagram of the arch provided for an embodiment of the present application; Figure 3 The arrangement diagram of the blasting hole provided for an embodiment of the present application.

[0016] In Figures 1-3 , 1, arch wall section; 101, arch top unit; 102, first arc-shaped side arch unit; 103, second arc-shaped side arch unit; 104, first straight line side arch unit; 105, second straight line side arch unit; 2, inverted arch section; 201, first inverted arch unit; 202, second inverted arch unit; 203, third inverted arch unit; 3, blasting hole. DETAILED DESCRIPTION

[0017] The present application will be further described below with reference to the drawings.

[0018] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar parts; in the description of the present application, it should be understood that if the terms "top", "bottom", "left", "right", "front", "back", "inner", "outer" and the like appear, the orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for exemplary description, and cannot be understood as a limitation on the present patent, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0019] Please refer to Figures 1-3 , an embodiment of the present application provides a tunnel full cross section with inverted arch excavation and support forming construction method, comprising the following steps: S1, construction preparation, specifically, measuring and lofting the working face, cleaning the working face of virtual slag; S2, making an arch frame, the arch frame comprising an arch wall segment 1 and an inverted arch segment 2, the arch wall segment 1 and the inverted arch segment 2 being assembled and connected, the arch frame being cold-bent and segmented in a factory, and then being assembled and connected through strength bolts at a construction site; S3, drilling a blast hole 3 in the working face, installing a detonator in the blast hole 3, blasting to obtain a tunnel section, and timely removing slag; S4, trimming the contour line of the tunnel section, specifically, using a milling machine and a hawk to trim the tunnel section, to ensure that the arch frame installation surface is flat and smooth, the inverted arch of the tunnel section is not over-excavated, and the bottom is free of floating slag and water accumulation, further, after trimming, the tunnel section is safety evaluated, and then a drainage system is constructed at the bottom of the tunnel section to facilitate drainage; S5, installing the arch frame to the tunnel section, connecting a steel mesh sheet to the arch frame and hanging the mesh, the number of arch frames being determined according to the axial size of the tunnel section, further, before installing the arch frame, the tunnel section is initially sprayed with concrete, and an anchor rod is constructed to strengthen the initial support of the tunnel section, after the initial spraying of concrete, acceptance is carried out, if the acceptance fails, the initial spraying of concrete is re-performed, and after the acceptance passes, the next construction step is carried out; S6, wet spraying concrete to the inverted arch segment 2 and the arch wall segment 1 to form a closed support ring, since the arch frame comprises the inverted arch segment 2 and the arch wall segment 1, the arch wall and the inverted arch of the tunnel section can be simultaneously supported, the inverted arch segment 2 and the arch wall segment 1 are simultaneously sprayed with concrete by using a wet spraying concrete device, are formed in layers according to the design thickness, and are ensured to be dense and uniform without shell cracking, to form a closed support ring at one time, effectively resist the large deformation load of surrounding rock, and avoid arch frame instability and deformation out of limits caused by long initial support opening time; S7, monitoring and measuring the tunnel section.

[0020] The present application realizes the synchronous development of inverted arch and arch wall support construction, breaks the structure closure lag and incomplete support caused by the lag construction of the inverted arch in the traditional construction method, forms a full-section and integral initial support structure, significantly improves the stability of the support structure, and the construction method is simple and convenient to operate, safe and high in construction efficiency.

[0021] As Figure 2As shown, the arch wall segment 1 comprises a vault unit 101, a first arc-shaped side arch unit 102 and a second arc-shaped side arch unit 103 connected to both ends of the vault unit 101 respectively, a first straight side arch unit 104 connected to the lower end of the first arc-shaped side arch unit 102, and a second straight side arch unit 105 connected to the second straight side arch unit 104. The inverted arch segment 2 comprises a plurality of inverted arch units, and both ends of the inverted arch segment 2 are connected to the first straight side arch unit 104 and the second straight side arch unit 105 respectively. The inverted arch segment 2 comprises a first inverted arch unit 201, a second inverted arch unit 202 and a third inverted arch unit 203 connected in sequence. The first inverted arch unit 201 is connected to the first straight side arch unit 104, and the third inverted arch unit 203 is connected to the second straight side arch unit 105. Specifically, steel plates are welded at the connecting ends of each unit, holes are punched on the steel plates, and then high-strength bolts are used to connect the two steel plates together, which will not be described in detail.

[0022] As shown in Figures 1-3 The milling excavator and the hawk hook are used to trim the contour line of the tunnel section, which significantly reduces the disturbance degree of the inverted arch area and ensures the integrity of the tunnel foundation and the adhesion quality of the subsequent support.

[0023] As shown in Figure 3As shown, the blasting holes 3 are arranged in a layered and segmented manner, and the blasting holes 3 include a first arch wall hole group, a second arch wall hole group, a first arch top hole group, a second arch top hole group, a third arch top hole group, a first left wall hole group, a second left wall hole group, a third left wall hole group, a fourth left wall hole group, a first right wall hole group, a second right wall hole group, a third right wall hole group, a fourth right wall hole group, a first inverted arch hole group, a second inverted arch hole group, and a third inverted arch hole group. The blasting holes 3 in the first arch wall hole group and the second arch wall hole group are arranged along the arch wall contour line of the tunnel face. The first arch wall hole group and the second arch wall hole group are sequentially arranged from the outside to the inside, starting from the contour line of the tunnel face. The first arch top hole group, the second arch top hole group, and the third arch top hole group are sequentially arranged from the outside to the inside. The first left wall hole group, the second left wall hole group, the third left wall hole group, and the fourth left wall hole group are sequentially arranged from the outside to the inside. The first right wall hole group, the second right wall hole group, the third right wall hole group, and the fourth right wall hole group are sequentially arranged from the outside to the inside. The first inverted arch hole group, the second inverted arch hole group, and the third inverted arch hole group are sequentially arranged from the outside to the inside. The center points of the blasting holes 3 in the first arch wall hole group and the second arch wall hole group are connected and match the arch wall contour line of the tunnel face. The center points of the blasting holes 3 in the first arch top hole group are on a first circular arc line. The center points of the blasting holes 3 in the second arch top hole group are on a second circular arc line. The center points of the blasting holes 3 in the third arch top hole group are on a third circular arc line. The center points of the blasting holes 3 in the first left wall hole group form a broken line. The center points of the blasting holes 3 in the first right wall hole group form a broken line. The center points of the blasting holes 3 in the second left wall hole group form a vertical line. The arrangement of the blasting holes 3 in the third left wall hole group, the fourth left wall hole group, the second right wall hole group, the third right wall hole group, and the fourth right wall hole group is similar to that in the first left wall hole group. The center points of the blasting holes 3 in the first inverted arch hole group are on a fourth circular arc line. The center points of the blasting holes 3 in the second inverted arch hole group are on a fifth circular arc line. The center points of the blasting holes 3 in the third inverted arch hole group are on a sixth circular arc line. The diameters of the first circular arc line, the second circular arc line, and the third circular arc line gradually decrease. The diameters of the fourth circular arc line, the fifth circular arc line, and the sixth circular arc line gradually decrease. A blank area is formed between the third arch top hole group, the fourth left wall hole group, the fourth right wall hole group, and the third inverted arch hole group. The blasting holes 3 in the prior art are mostly arranged in a full form and horizontally. After blasting and excavation, the tunnel cross section is not accurate, and a large amount of time is needed for trimming. A large number of detonators are required. The arrangement of the blasting holes 3 in the present application is accurate, can accurately blast and excavate, reduces the workload of trimming, ensures accurate blasting, and reduces the amount of detonators used.

[0024] When the contour line of the tunnel cross section is trimmed, the tunnel cross section cannot be under-excavated within 1 m above the springing, and other parts are allowed to be under-excavated by not more than 0.1 m per 1 m 2 not more than 0.1 m 2The maximum under-excavation value of the individual protruding part is not greater than 5cm, and the individual protruding part refers to a local single tooth-shaped small protrusion on the contour line of the tunnel section after the excavation is completed and the milling cannot remove.

[0025] The wet spraying concrete adopts early high-strength wet spraying concrete, the 8h strength is not less than 10MPa, the 24h strength is not less than 15MPa, and the surface flatness of the wet spraying concrete is not greater than 1 / 2.

[0026] As shown in Figure 2 When the arch frame is installed, the arch frame is positioned on the tunnel section after trimming, the locking foot rib is welded at the lower end of the arch wall section 1, the locking foot hole is constructed below the locking foot, and the locking foot rib is inserted into the locking foot hole.

[0027] The detonator adopts an electric control electronic detonator, and the delay blasting is performed.

[0028] Specifically, the construction preparation step further includes laying out the crown settlement, peripheral convergence and inverted arch displacement monitoring points, arranging the monitoring points near the crown of the working face, near the contour lines of the two sides of the arch wall and near the inverted arch according to the on-site construction condition, setting the sensing device on the monitoring points, realizing the surrounding rock response feedback and dynamic support adjustment, collecting the monitoring data of the crown settlement, peripheral convergence and inverted arch displacement by the sensing device, cooperating the monitoring data with the total station instrument on the working face, analyzing the response characteristics of the closed support ring, realizing the construction process early warning and parameter correction, further setting the alarm device, automatically triggering the alarm combined with the deformation trend, adjusting the closed support ring, constructing the whole-process closed-loop control system with controllable high-stress construction process risks, realizing the controllable deformation whole process, constructing the support dynamic adjustment mechanism based on the monitoring measurement feedback, improving the construction whole-process risk control ability and safety guarantee level, and according to the on-site construction condition, the reflective sheet can also be set on the monitoring points for auxiliary monitoring.

[0029] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the difference from other embodiments. In particular, for the system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the description of the method embodiments. In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the specification. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0030] The above only describes the embodiments of one or more embodiments of the specification, and is not intended to limit one or more embodiments of the specification. Those skilled in the art can make various changes and changes to one or more embodiments of the specification. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the specification shall be included in the scope of claims.

Claims

1. A tunnel full-section with inverted arch excavation support forming construction method, characterized in that: The steps include: Construction preparation; Producing an arch frame, the arch frame comprising an arch wall section and an inverted arch section, and assembling and connecting the arch wall section and the inverted arch section; Drill holes on the tunnel face to obtain blasting holes, install detonators in the blasting holes, and blast to obtain the tunnel section; trimming the contour line of the tunnel section; Installing the arch frame to the tunnel section, connecting the steel mesh to the arch frame and hanging the mesh; Wet-spray concrete on the inverted arch section and the arch wall section to form a closed support ring; The tunnel section is monitored and measured.

2. The tunnel full-section with invert arch excavation support forming construction method according to claim 1 is characterized in that: The arch wall section includes a vault unit, a first arcuate side vault unit and a second arcuate side vault unit respectively connected to the two ends of the vault unit, a first straight side vault unit connected to the lower end of the first arcuate side vault unit, and a second straight side vault unit connected to the second straight side vault unit. The inverted vault section includes multiple inverted vault units, and the two ends of the inverted vault section are respectively connected to the first straight side vault unit and the second straight side vault unit.

3. The tunnel full-section with inverted arch excavation support forming construction method according to claim 2 is characterized in that: The inverted arch section includes a first inverted arch unit, a second inverted arch unit and a third inverted arch unit connected in sequence, wherein the first inverted arch unit is connected to the first linear side arch unit, and the third inverted arch unit is connected to the second linear side arch unit.

4. The tunnel full-section with invert arch excavation support forming construction method according to claim 1 is characterized in that: The contour line of the tunnel section is trimmed using a milling machine and an eagle hook.

5. The tunnel full-section with invert arch excavation support forming construction method according to claim 2 is characterized in that: The blasting holes are arranged in layers and sections.

6. The tunnel full-section with invert arch excavation support forming construction method according to claim 3 is characterized in that: When trimming the outline of the tunnel section, the tunnel section cannot be undercut within 1m above the arch foot, and other parts are allowed to be undercut every 1m. 2 No more than 0.1m 2 .

7. The tunnel full-section with inverted arch excavation support forming construction method according to claim 1 is characterized in that: Wet sprayed concrete uses early high-strength wet sprayed concrete, with an 8-hour strength of not less than 10MPa, a 24-hour strength of not less than 15MPa, and a surface flatness of not more than 1 / 2.

8. The tunnel full-section with invert arch excavation support forming construction method according to claim 1 is characterized in that: When installing the arch frame, the arch frame is positioned on the trimmed tunnel section, a locking foot reinforcement is welded at the lower end of the arch wall section, a locking foot hole is constructed below the locking foot, and the locking foot reinforcement is inserted into the locking foot hole.

9. The tunnel full-section with invert arch excavation support forming construction method according to claim 1, characterized in that: The detonator adopts an electrically controlled electronic detonator.

10. The tunnel full-section with invert arch excavation support forming construction method according to claim 1, characterized in that: The construction preparation steps include arranging monitoring points for arch crown sinking, perimeter convergence, and invert arch displacement.

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