TOP-DOWN SEQUENTIAL-BUILDING CONSTRUCTION METHOD FOR DEEP AND LARGE VERTICAL SHAFT CAVERN GROUP

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application serial no. 202410802067.0, filed on Jun. 20, 2024. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The disclosure relates to the technical field of tunnel construction, specifically, relates to a top-down sequential-building construction method for a deep and large vertical shaft cavern group.

Description of Related Art

For the safe operation of long and large highway tunnels in later periods, ventilation conditions are indispensable key factors. To ensure ventilation and emergency fire smoke exhaust capabilities during a tunnel operation period, a usual method is to set up a ventilation inclined shaft or vertical shaft at a location having better geological conditions in the tunnel site to meet disaster prevention and rescue requirements of the tunnel.

Square vertical shafts, due to advantages of higher space utilization rates, are widely used in urban environments or locations having better stratum conditions. Currently, the construction method for square vertical shafts mainly adopts a reverse integral inverted-wall method. However, adopting the inverted-wall method has the following problems:

First, during the construction process, the structure is suspended on a vertical shaft wall. Before the vertical shaft is completely excavated to a bottom, the structure is always in a suspended state. Vibration generated by blasting and excavation will have a certain disturbance effect on the structure.

Second, protection of a lining structure is relatively difficult, posing greater safety risks. Moreover, adopting large steel formworks for constructing the lining structure, the steel formworks themselves are relatively heavy. Construction hoisting is frequent, and various cross operations are frequent during mounting. The hoisting process has large interference between processes, many risk sources, greater potential safety hazards, and the construction quality is difficult to guarantee.

Therefore, for deep and large vertical shafts having multiple contact channels, a more reasonable construction sequence arrangement and construction method are required to ensure construction efficiency and quality of a project.

In view of this, we propose a top-down sequential-building construction method for a deep and large vertical shaft cavern group.

SUMMARY

The disclosure aims to provide a top-down sequential-building construction method for a deep and large vertical shaft cavern group having a more reasonable construction sequence to solve the problems raised in the above-mentioned background technology.

To achieve the above-mentioned objective, the disclosure provides the following technical solutions.

A top-down sequential-building construction method for a deep and large vertical shaft cavern group includes the following steps. Preparation is made for a construction. A vertical shaft locking beam is constructed. A vertical shaft is constructed. A post-construction maintenance is performed. The vertical shaft is constructed through a staged construction, which includes the following steps.

• • S1, the construction is performed from a vertical shaft surface to a contact air channel elevation.
  • S2, a contact air channel is constructed.
  • S3, the construction is performed from the contact air channel elevation to a vertical shaft bottom.

Both the constructions from the vertical shaft surface to the contact air channel elevation and from the contact air channel elevation to the vertical shaft bottom include a step of constructing a lining structure from a bottom to a top.

As a further description of the disclosure, the construction of the lining structure includes the following steps. A single-side cantilever climbing formwork is mounted. A symmetric and layered concrete pouring is performed. A formwork is removed. A formwork removal strength required for removing the formwork is ≥100%, and the single-side cantilever climbing formwork is a detachable and reusable climbing formwork.

As a further description of the disclosure, when constructing the vertical shaft, each stage of the construction includes the following steps sequentially. A blasting is performed. An excavation is performed. A support is provided. The blasting adopts a full-face one-time blasting and a layered integral blasting. After the blasting, the excavation is performed by an excavator, and a slag soil generated from the excavation is hoisted and removed. The step of providing the support includes a step of sequentially providing a primary support and constructing the lining structure.

As a further description of the disclosure, providing the primary support includes the following steps. A preliminary shotcrete spraying, a steel grid construction, a steel mesh construction, a hollow grouting anchor construction, and a secondary shotcrete spraying are performed.

As a further solution of the disclosure, the vertical shaft is horizontally and sequentially divided into a vertical shaft ascending and descending ladder space, a vertical shaft slag removal hoisting channel, and an excavator parking area. A slag hoisting equipment is disposed within the vertical shaft slag removal hoisting channel. The excavator and the slag hoisting equipment are staggered with each other. A protective steel plate is disposed at a top of the excavator parking area.

As a further description of the disclosure, at a tunnel portal transition portion of the contact air channel, an upper and lower bench method is adopted for construction into a tunnel. A reinforced section is disposed at a tunnel portal connecting the vertical shaft and the contact air channel. A tunnel portal portion of the contact air channel and a vertical shaft wall are integrally poured.

As a further description of the disclosure, in constructing the contact air channel, an inside-out lining structure construction method is adopted for constructing the lining structure.

As a further description of the disclosure, constructing from the contact air channel elevation to the vertical shaft bottom and constructing from the vertical shaft surface to the contact air channel elevation include an identical workflow of performing an excavation, providing a support, and performing a lining pouring.

Compared with the prior art, beneficial effects of the disclosure are as follows:

• • 1. In the top-down sequential-building construction method for the deep and large vertical shaft cavern group, the construction method has fewer process conversions, and a length of construction footage may be flexibly adjusted according to actual conditions, being advantageous for construction organization and resource investment.
  • 2. In the top-down sequential-building construction method for the deep and large vertical shaft cavern group, constructing the lining structure has no risk of increasing the structural dead weight. Blasting causes less disturbance to the structure, being safe and reliable.
  • 3. In the top-down sequential-building construction method for the deep and large vertical shaft cavern group, constructing the lining structure is performed from a bottom to a top sequentially, adopting small steel formworks. The process is simple, operators operate conveniently, the formworks may be recycled, hoisting frequency is low, hoisting risk is relatively low, and process interference is relatively low.
  • 4. In the top-down sequential-building construction method for the deep and large vertical shaft cavern group, constructing the lining structure sequentially from a bottom to a top may avoid risks of damage to construction waterproofing and reserved rebars, and avoid hidden dangers of construction joints and non-dense concrete pouring. The excavation has a low risk of damaging the completed structure. Reserving concrete feeding openings and vibration windows is not required. The overall construction quality is more controllable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a construction flow of the deep and large vertical shaft cavern group of the present solution.

FIG. 2 is a schematic diagram of a vertical shaft locking beam structure of the present solution.

FIG. 3 is a schematic diagram of a slag removal process after blasting.

FIG. 4 is a schematic diagram of a primary support.

FIG. 5 is a schematic diagram of constructing from a vertical shaft surface to a contact air channel elevation and constructing the contact air channel.

FIG. 6 is a schematic diagram of constructing from the contact air channel elevation to a vertical shaft bottom.

DESCRIPTION OF THE EMBODIMENTS

The technical solutions in embodiments of the disclosure will be clearly and completely described below in combination with drawings in embodiments of the disclosure. Obviously, described embodiments are only a part of embodiments of the disclosure, but are not all embodiments. Based on embodiments of the disclosure, all other embodiments obtained by a person having ordinary skill in the art without performing creative work fall within a protection scope of the disclosure.

As shown in FIG. 1, the embodiment provides a top-down sequential-building construction method for a deep and large vertical shaft cavern group, including preparing for a construction, constructing a vertical shaft locking beam, constructing a vertical shaft, and performing a post-construction maintenance. Constructing the vertical shaft is a staged construction, including the following steps: S1, constructing from a vertical shaft surface to a contact air channel elevation; S2, constructing a contact air channel; S3, constructing from the contact air channel elevation to a vertical shaft bottom. Both constructing from the vertical shaft surface to the contact air channel elevation and constructing from the contact air channel elevation to the vertical shaft bottom include constructing a lining structure from a bottom to a top.

An improvement of the embodiment lies in that the vertical shaft is constructed in sections, helping better control a construction schedule, ensuring construction quality of each stage meets a preset standard, improving an overall construction quality. Meanwhile, based on the sectional construction, constructing a lining structure from a bottom to a top is adopted, further enhancing stability and safety of a vertical shaft structure, improving an overall load-bearing capacity and seismic performance of the vertical shaft.

Considering that preparation work needs to be performed before construction, avoiding additional time required for deploying materials, personnel, and machines during construction, delaying construction time, thus, preparing for the construction includes personnel arrangement, including blasters, excavator drivers, gantry crane drivers, etc. Material arrangement includes shotcrete, anchors, section steel supports, etc. Mechanical equipment arrangement includes excavators, gantry cranes, concrete spraying machines, grouting pumps, etc.

Before constructing the vertical shaft, constructing a vertical shaft locking beam 1 is required to ensure stability and safety of a shaft and prevent underground water seepage. Therefore, constructing the vertical shaft locking beam 1 sequentially performs the following steps: measuring and setting out; slope excavation; slope support; cushion layer pouring; rebar binding; formwork mounting; concrete pouring; concrete curing. The finally completed vertical shaft locking beam 1 is shown in FIG. 2.

When constructing a first stage of the vertical shaft, after designing a blasting scheme according to actual stratum conditions on site, earth-rock excavation of the vertical shaft is performed. Since an excavation cross-section of the vertical shaft is relatively small, full-face one-time blasting may be adopted, and layered integral blasting is adopted, reducing a number of mechanical lifts during the process, reducing on-site waiting time of explosives, and meanwhile meeting requirements for preliminary support sealing.

As shown in FIG. 3, slag removal is required after blasting to expand space. Therefore, after completing earth-rock blasting or crushing, slag soil is loaded by an excavator 5 into a slag removal bucket 6. Slag hoisting equipment lifts the slag removal bucket 6, transferring the slag soil to a temporary slag storage yard, then transporting by a slag truck to a slag disposal yard. To avoid a risk of cross operation of vertical lifting during slag removal, a space of the vertical shaft is divided. A middle area of the vertical shaft is a vertical shaft slag removal hoisting channel 3. Two sides of the vertical shaft slag removal hoisting channel 3 are respectively a vertical shaft ascending and descending ladder space 2 and an excavator 5 parking area. Below the vertical shaft slag removal hoisting channel 3, the vertical shaft ascending and descending ladder space 2, and the excavator 5 parking area is an unexcavated area 7. The slag removal bucket 6 and the excavator 5 are staggered with each other. Meanwhile, a protective steel plate 4 is covered at a shaft mouth of the vertical shaft for isolation. When performing hoisting work, the excavator 5 parks below the protective steel plate 4 in the vertical shaft, avoiding that after the slag removal bucket 6 is hoisted out of the vertical shaft, when slag soil in the slag removal bucket 6 is transferred, some slag soil falls into the vertical shaft again, causing damage to the excavator 5. It is further noted that slag hoisting equipment of the embodiment selects a gantry crane. Through coordination between the gantry crane and the slag removal bucket 6, the slag removal bucket 6 is vertically lifted, thereby hoisting slag soil out of the vertical shaft.

As shown in FIG. 4, to prevent surrounding rocks from peeling and falling, after completing segmented earth-rock excavation of the vertical shaft, concrete is immediately sprayed below a lining poured section 8, timely sealing and leveling an excavation surface. After sequentially mounting a section steel grid 9, a steel mesh 10, and a hollow grouting anchor 11, a second spraying to a design thickness is performed. Through the second spraying to the design thickness, structural integrity of the vertical shaft may be ensured, avoiding structural defects or potential safety hazards caused by insufficient concrete thickness. Moreover, the design thickness is determined based on comprehensive consideration of multiple factors such as uses, geological conditions, and loads of the vertical shaft. The second spraying to the design thickness may ensure the vertical shaft meets design requirements, improving stress performance of the vertical shaft, enabling the vertical shaft to better withstand effects of various loads such as dead weight, water and soil pressures, etc.

As shown in FIG. 5, when the vertical shaft is excavated to a bottom elevation of a contact air channel 12, excavation and support of a vertical shaft main body are suspended. First-stage lining pouring of the vertical shaft is performed. A vertical shaft lining formwork adopts a single-side cantilever climbing formwork. Concrete pouring is performed symmetrically and in layers according to a sequence of constructing a first segment 13 of the lining structure, constructing a second segment 14 of the lining structure, and constructing a third segment 15 of the lining structure. After a vertical shaft bottom plate is poured and reaches a preliminary strength, supports may be erected. Reinforcement and waterproofing are constructed. Subsequently, a formwork is mounted, and concrete is poured. During erecting a next segment of supports and constructing reinforcement and waterproofing, concrete of a previous segment reaches a formwork removal strength, i.e., formwork removal strength≥100%, the formwork may be removed and recycled, performing concrete pouring of a next segment of lining. Meanwhile, a disc-lock scaffolding 16 is erected synchronously as a construction platform, facilitating workers to perform construction operations. When concrete pouring of the lining is completed, a construction procedure of switching from the vertical shaft to the contact air channel 12 is performed.

Constructing the air channel includes the following steps: blasting, excavating, and supporting the contact air channel 12, and constructing a lining structure of the contact air channel 12. In blasting, excavating, and supporting the contact air channel 12, an upper and lower bench method is required at a tunnel portal transition portion of the air channel for tunneling. After an upper bench excavation is completed, a lower bench excavation is timely performed to a bottom, ensuring an arch foot sits on stable bedrock. Other operations are the same as the first-stage construction of the vertical shaft. Subsequently, constructing the lining structure of the air channel adopts an inside-out lining structure construction method. It is further noted that a tunnel portal connecting the vertical shaft and the contact air channel 12 is provided with a reinforced section. A tunnel portal portion of the contact air channel 12 and a vertical shaft wall are integrally poured to increase stability of an integral structure.

As shown in FIG. 6, after completing constructing the air channel, constructing from the contact air channel elevation to a vertical shaft bottom is performed. Excavation is supported simultaneously. Procedures of excavation supporting and lining pouring are the same as excavation in the first stage of the vertical shaft. After completing the construction, protection of finished concrete should be properly performed. After passing acceptance, the shaft is put into use to assist mainline construction of a tunnel.

It is further noted that parameters of primary support for the vertical shaft, such as a thickness of shotcrete, size of the steel mesh 10, sizes, layout modes, and grouting pressures of the hollow grouting anchor 11, all need to be confirmed after verification calculations according to actual stratum conditions. A number of segments, a pouring height of each segment, and sizes of pouring steel formworks adopted in pouring the vertical shaft lining formwork need to be adjusted according to actual pouring heights.

Technical effects of the disclosure: the top-down sequential-building construction method for the deep and large vertical shaft cavern group of the disclosure solves problems of structure suspension during constructing the vertical shaft, disturbance of vibration to the structure, and difficulty of constructing the lining structure. By segmenting construction of the vertical shaft and adopting constructing the lining structure from a bottom to a top, an overall construction quality is improved. Meanwhile, during segmented construction, constructing the lining structure does not increase risks of structural dead weight. Blasting the vertical shaft causes smaller disturbance to the structure, being safe and reliable. While constructing the lining structure, small steel formworks are adopted, a process is simple, operators operate conveniently, the formworks may be recycled, hoisting frequency is low, hoisting risk is relatively low, and process interference is relatively low. Meanwhile, damage to construction waterproofing and reserved rebars, hidden dangers of construction joints and non-dense concrete pouring may be avoided. Excavation work has lower risks of damaging a completed structure. Reserving concrete feeding openings and vibration windows is not required. Overall construction quality is more controllable. Process conversions in the entire construction method are fewer. A length of construction footage may be flexibly adjusted according to actual conditions, being advantageous for construction organization and resource investment.

Although the specification is described according to the embodiments, not every embodiment contains only one independent technical solution. This narration manner of the specification is merely for clarity. A person skilled in the art should regard the specification as a whole. Technical solutions in various embodiments may also be appropriately combined to form other embodiments understandable by a person skilled in the art.

Therefore, the above descriptions are exemplary embodiments of the disclosure and does not intend to limit an implementation scope of the disclosure. That is, various equivalent transformations made according to a scope of claims of the disclosure all belong to a protection scope of claims of the disclosure.