Professional Tunnel Lining Formwork System

During the secondary lining pouring process, the arch crown is a construction blind spot for concrete pouring. To ensure construction quality, five detection points are set to check whether the pouring is in place. An audible and visual alarm will sound at each detection point, and the alarm time can be arbitrarily set.

To prevent the five detection points from failing and to ensure construction quality, four additional inlet pressure detectors are added. These serve two purposes: firstly, to perform secondary anti-void detection through pressure; and secondly, to prevent construction accidents such as membrane bursting and arch crown deformation during the blind spot construction process. The parameters of these four inlet pressure detectors can be arbitrarily set from 0% to 100%, depending on the on-site construction. An alarm will sound if the limit is exceeded.

Because the previously poured concrete is only in its initial setting state, it is easy for the existing initially set concrete to crack during the second formwork erection after demolding. To ensure that the initial set surface is not cracked during the second formwork erection, we added 5 crack prevention detection points. The protection value can be set arbitrarily from 0% to 100%, depending on the initial setting condition. An alarm is triggered immediately if the set value is exceeded.

Since the secondary lining pouring process is a closed construction, accidents such as formwork rolling and uneven formwork are prone to occur during pouring on both sides. To ensure balanced pouring on both sides, construction workers repeatedly climb over the work opening to observe the balanced pouring on both sides, which is arduous work. Based on this, we developed a real-time streamlined concrete level display device. This device provides real-time observation of the concrete level on both sides with centimeter-level accuracy. The alarm values ​​for both sides can be set arbitrarily, constantly reminding pouring workers of the pouring position, thereby preventing construction accidents such as formwork rolling and uneven formwork.

During secondary lining construction, seasonal variations and inconsistent ambient temperature and humidity at the construction site are significant. Considering these environmental factors, we added ambient temperature and humidity monitoring, as well as concrete temperature monitoring. We adjust the overlap ratio based on these changes to ensure construction quality.

During secondary lining pouring, to ensure balanced pouring on both sides, concrete flow rate monitoring allows for real-time monitoring of the pouring status on both sides. Alarms can be set for the pouring volume values ​​on both sides to prevent accidents caused by uneven pouring and ensure construction quality.

Due to the limitations of on-site construction conditions during secondary lining pouring, the installation of a wireless video monitoring system allows for real-time monitoring of the construction status, adjustment of the construction plan, and timely understanding of unexpected situations during construction, enabling prompt adjustments to the construction plan.

During the secondary lining pouring process, the instability of construction site conditions and high vibration levels can easily cause instability in various detection signal data, leading to false alarms and missed alarms. Based on the original functions, a new generation of non-contact signal detection system has been upgraded to further ensure the reliability of the secondary lining construction early warning system.

In secondary lining construction, to ensure safe and smooth construction, and to monitor and adjust the construction site conditions at any time, cloud information technology provides the best support for command personnel to have a clear understanding of the construction progress and the early warning system. Users can view and monitor anytime, anywhere, print (tabular format) construction early warning data on-site for filing, retrieve early warning data anytime via USB drive, and store it long-term.

To ensure the density and prevent honeycombing issues in secondary lining construction, we have developed a new generation of intelligent vibration systems. This system allows for the automated, one-button operation of setting the number of vibrations, amplitude, time, intervals for stopping, and repeated vibration for each unit or group, ensuring construction quality while preventing insufficient density, leakage, honeycombing, and other defects during concrete pouring.

Effectively improves the physical quality and appearance of layered concrete pouring for secondary lining. The cart-type placing system eliminates the need for manual pipe disassembly, connection, replacement, and cleaning; only one operator is required to easily operate the remote control for layered, window-by-window pouring. This reduces labor intensity, the number of operators, increases construction efficiency, and lowers construction costs and safety risks.

Utilizing a lightweight and standardized design, the upper and lower end-capping devices feature quick-release structures, as do the lower end-capping device and the main formwork. The upper end-capping device is telescopically adjustable, and rubber blocks replace wooden molds, completely eliminating the need for wooden mold sealing. It is highly adaptable, easy to assemble and disassemble, and the formwork can be reused multiple times. This reduces construction costs. Adjacent components are in close contact, ensuring good sealing. Operators can observe the concrete pouring progress in real time from outside the end-cap board, preventing under-pouring or high-pressure bursting. It also prevents grout leakage at construction joints.

The flexible overlap technology uses rubber material, 10 cm wide and 2 cm thick, with a compressive strength of not less than 5 MPa. The rubber is fixed to a rigid support base with bolts. This prevents cracking of the poured concrete at the circumferential/longitudinal construction joints during formwork erection, creating a sealed space at the lining location to prevent segregation, aggregate separation, and other concrete quality problems caused by grout leakage.

The arch casting pipe opening has been changed from a vertical position to a 60° angled casting hole to reduce flow friction and cohesion of the arch concrete.

1) The angled connection of the concrete casting opening ensures the direction of concrete flow, allowing it to reach the formwork end first.

2) The shorter distance between the casting opening and the formwork end ensures that the concrete quickly fills the formwork end, allowing for rapid reverse venting.

3) The reverse venting process removes air from the formwork and also compacts the previously poured concrete with new concrete.