The tunnel lining trolley is a construction equipment used for the secondary lining of concrete in the tunnel construction. It is supported by a steel structure gantry and forms a concrete pouring space between the formwork and the excavation face. The trolley uses hydraulic cylinders and jacks to adjust the formwork's position for installation and removal. It has the characteristics of being low cost, reliable structure, fast lining speed, easy operation, and good concrete forming quality. It can significantly speed up the construction process and minimize disruptions to other tunnel construction activities. Therefore, formwork lining trolleys are widely used in tunnel construction projects such as highways, railways, hydropower, and urban subways.

Boyoun Tunnel Lining Trolley 

This article will introduce tunnel formwork lining trolleys from the following three perspectives. Let's dive in!

  1. Importance of Tunnel Lining Trolley

  2. Installation of Tunnel Lining Trolley

 3. Categorization of Tunnel Lining Trolley

Importance of Tunnel Lining Trolley

In tunnel construction, in addition to initial support, secondary lining is also necessary considering various factors. Secondary lining refers to constructing an inner lining using materials such as concrete to reinforce the initial support, optimize the road drainage system, enhance the appearance, and facilitate the installation of communication, lighting, monitoring, and other facilities, meeting the requirements of modern high-speed road tunnel construction. The tunnel formwork lining trolley is a specialized equipment used in the secondary lining of the tunnel and is essential for lining construction on the inner walls of the tunnel.

Installation of Tunnel Lining Trolley

The installation of the lining trolley can be done inside or outside the tunnel. For inside installation, the lifting brace must be securely fixed to the tunnel wall first. The trolley components are lifted using a manual hoist. For external installation, the trolley components are lifted using a hydraulic crane mounted on a vehicle. Once the trolley is installed, the walking mechanism will activate to move the trolley into the tunnel. The installation of the tunnel lining trolley usually follows the following steps:

1.  Determine installation reference: Check if the ground is level and meets the design installation requirements.

2.  Maintain the tracks: The tracks must be fixed and meet the design requirements for center distance, height, and accuracy with the tunnel walls.

3.  Gate frame installation: Ensure that all connections are secure and align the traveling wheels with the center of the tracks. After the entire gate frame is installed, measure the centerline of the two longitudinal beams to ensure that the diagonal length does not exceed 20mm.

4.  Position the traverse trolley: Install the traverse trolley on the side beams of the gate frame and adjust the cylinders to the middle position.

5.  Install the support frame assembly: Install the longitudinal beams, followed by the side beams, middle beams, side columns, and middle columns, etc. Ensure that the centerline of the longitudinal beams is parallel to the centerline of the gate frame and the diagonal length error should not exceed 20mm.

6.  Install the formwork assembly: Start by installing the top mold, followed by the left and right side molds, and finally the connecting beams and lateral supporting jacks.

7.  Install the hydraulic station and hydraulic pipelines, and connect the electrical wiring.

8.  Check all components: Check if all bolts are tightened, the connecting pins can rotate smoothly, the hydraulic components and pipelines have any leaks, and the electrical wiring is properly insulated.

9.  Check all design dimensions: Check if the important dimensions of the trolley meet the design requirements, such as the height from the trolley track surface to the highest point of the template, the width of the template edge, and the center distance of the template tracks.

Categorization of Tunnel Liner Trolley

According to the applicable tunnel length, template trolleys can be classified into the following three types.

Simple Lining Trolley

This type of trolley is suitable for short tunnel construction, especially for tunnels with complex geometric shapes, frequent process conversions, and strict construction requirements. These trolleys adopt a steel arch frame structure and commonly use standard steel formwork. The design should consider the stiffness of the steel formwork and the spacing between the steel arch frames should not be too large. They are usually powered externally and all template removal is done manually. The lining construction speed is slower, but the trolley has a low cost and can be designed with a passageway for vehicle transportation in the middle.

Fully Hydraulic Automatic Walking Lining Trolley

Hydraulic trolley is primarily used for medium to long tunnel construction projects that require high construction progress and surface quality. These trolleys are usually designed with integral steel moulds, hydraulic cylinder mould removal, supported by screw jacks, and equipped with electric reducers for automatic walking or hydraulic cylinder for step-by-step automatic walking. They do not use alkaline conveying pumps for grouting, and the installation position of the inner side of the gate support under inclined support should be considered in the design to ensure optimal force distribution. When lining a tunnel with a slope, attention should be paid to the deformation of the support screw jack and the lifting of the hydraulic cylinder due to adjusting the lining elevation. Therefore, the design should consider restraining structures or adjustment systems to address the problem of horizontal forces caused by the height difference.

Grid-type Lining Trolley

This type of trolley is primarily used for large-span tunnels and underground chamber construction. It has significant structural differences from traditional tunnel lining trolleys. The gate frame of the trolley is not subjected to stress during construction, and the support components of the template are the top-ground screw jacks of the side mold arch feet. The gate frame only experiences vertical downward forces during template removal and walking processes without lateral pressure. The gate frame 's stiff design helps prevent deformation. During construction or when walking through a tunnel with a slope, the height adjustment is achieved by lifting the hydraulic cylinder at the lower part of the gate frame, ensuring a overall levelness and improving stability. The grid-type trolley eliminates the use of support screw jacks, making trolley positioning simple, saving manpower and resources, improving work efficiency, and reducing construction costs.

 These three types of template trolleys are suitable for various tunnel construction scenarios. Opting for the appropriate trolley for the length of the tunnel can improve construction efficiency and quality.

To Wrap Up

Tunnel lining trolley is a crucial tunnel construction equipment. It provides efficient and accurate solutions for tunnel construction by transporting and installing lining materials. With the continuous development of tunnel construction technology, tunnel lining trolleys are constantly evolving and improving to meet different construction needs. In the future, tunnel lining trolleys will continue to play a crucial role.

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