In tunnel construction, drainage channels are responsible for draining accumulated water to ensure structural stability, while cable trays handle the orderly routing of power and communication lines. The construction quality of both plays a critical role in the long-term safe operation of the tunnel. As specialized equipment tailored for constructing these types of structures, the drainage-channel and cable-tray trolley is gradually replacing traditional manual and simple mechanical methods, becoming one of the key pieces of equipment in modern tunnel construction. The drainage-channel and cable-tray trolley is a mechanized device that integrates functions such as walking, positioning, formwork support, and pouring assistance. Its core advantage lies in its targeted design that perfectly suits the confined working spaces typical of tunnels. Structurally, mainstream trolleys typically consist of four core components: First, the walking system—usually driven by a motor paired with a reducer to power steel wheels, enabling overall movement along pre-established tracks. Some high-end models are equipped with soft-start motors, which help avoid collision damage to already constructed structures during movement. Second, the formwork system—using integral steel molds that, after polishing, achieve a smooth surface, effectively eliminating misalignment and slurry leakage issues common in conventional assembled formwork. These molds can also be custom-made according to the specific dimensions of drainage channels and cable trays, accommodating various cross-sectional requirements. Third, the hydraulic system—utilizing cylinders to control the lifting, lateral movement, and demolding of the formwork. The independent control of each cylinder allows precise adjustment of structural dimensions, making it well-suited for complex construction scenarios such as tunnel transition sections. Fourth, the support and positioning system—employing positioning clips and triangular brackets to reinforce the formwork, preventing deformation during concrete pouring and ensuring construction accuracy. Compared to the traditional segmented construction method using small steel forms, the application of this trolley offers significant advantages. In terms of efficiency, under the traditional method, four workers could complete only 15 linear meters of assembly on one side per day; however, the trolley enables simultaneous construction on both sides, allowing the same four workers to pour 24 linear meters per day, greatly reducing the time required for formwork installation and removal. In terms of quality, the use of integral formwork reduces construction joints, and hydraulic positioning eliminates human-operated errors, resulting in straight structural profiles and smooth surfaces with significantly lower incidence rates of common defects such as honeycomb surfaces and exposed rebar. In terms of cost, the trolley reduces consumption of temporary support materials and labor input. According to calculations, the comprehensive cost per meter under the traditional method is about 208 yuan, whereas the trolley-based construction can reduce this cost to around 34 yuan per meter, yielding substantial economic benefits over the long term. Currently, this type of trolley has been widely adopted in highway and railway tunnels, as well as in subway projects and underground passages at airports. With ongoing technological upgrades, some trolleys have even integrated intelligent monitoring modules that provide real-time feedback on formwork positioning accuracy and concrete pouring status, further driving the construction of tunnel ancillary structures toward greater efficiency and precision.

Article 2: Construction Techniques and Key Quality Control Points for Cable Trench Carriages in Drainage Ditches

The efficient application of cable trench carts depends not only on the performance of the equipment itself but also on standardized construction procedures and stringent quality control measures. Mastering the core construction stages and key quality-control points is essential to ensure that cable trench and cable tray installations meet regulatory requirements. The following outlines a general construction and control process.

I. Pre-construction Preparation

Before construction begins, three core tasks must be completed. First, site preparation: Clear away debris and loose materials from the tunnel’s inverted arch filling surface; based on the design drawings, carry out surveying and layout work, marking the centerlines, boundary lines, and elevation control points for drainage ditches and cable trays. Second, equipment commissioning: Check whether the trolley’s traveling system operates smoothly and whether the hydraulic cylinders extend and retract flexibly. The formwork surfaces must be ground and cleaned thoroughly and then coated with a release agent to prevent concrete from sticking. Third, material preparation: Ensure that all raw materials—such as C30 concrete meeting strength requirements and HPB300 reinforcing bars—are readily available. Complete the fabrication and tying of reinforcing bars in advance, and make sure that the rebar cover spacers are securely positioned.

II. Core Construction Process

1. Positioning the trolley: Use the traveling system to move the trolley to the construction section, adjust its position according to the layout markings, and ensure that the formwork aligns precisely with the design lines. 2. Formwork installation and reinforcement: Activate the hydraulic system to unfold the formwork, use positioning clips to secure the relative positions of adjacent formwork panels, install end stop boards to seal the ends, and reinforce the external support with triangular brackets to withstand the lateral pressure from the concrete. 3. Concrete pouring: Pour the concrete in one continuous operation using a layered compaction method. Employ an immersion vibrator to eliminate air bubbles. During the pouring process, closely monitor the condition of the formwork; if any displacement occurs, promptly make fine adjustments via the hydraulic system. 4. Demolding and relocation: Once the concrete strength reaches the design requirements, activate the hydraulic cylinders to retract and release the formwork. Clean the formwork surface, apply lubricant for maintenance, and then move the trolley to the next construction section. 5. Curing and follow-up: Perform water sprinkling or film covering curing on the completed structure to prevent shrinkage cracks caused by inadequate curing.

III. Key Quality Control Points

Quality control must focus on five key stages. First, strictly control the accuracy of formwork: after installation, check the cross-sectional dimensions, keeping allowable deviations within ±10 mm and ensuring that the gap between adjacent formwork joints does not exceed 2 mm. Second, standardize concrete construction procedures by controlling the pouring speed and adjusting vibration time so that the concrete surface begins to bleed without any air bubbles, thereby preventing segregation caused by over-vibration. Third, carefully determine the timing for form removal—generally, formwork should be removed only when the concrete strength reaches at least 50% of its design strength, thus avoiding premature removal that could damage the surface. Fourth, strengthen alignment control: for curved sections of tunnels, use adjustable support columns on the tunnel lining carriages to compensate for height differences and ensure that the trench slopes meet drainage requirements. Fifth, conduct thorough inspections of finished products: after construction, randomly sample and test concrete strength at specified intervals, and use a ruler to measure surface smoothness, ensuring compliance with the quality inspection and evaluation standards for highway or railway projects.