Building a Dam and Weaving a Net - Fine Operation of Concrete Arm Frame Fabric Equipment in Dam Reinforcement Projects
At the site of the reinforcement project for a high-altitude reservoir in Qinghai, three concrete arm frame fabric equipment are weaving a special ‘reinforcement net’ on the upstream slope of the dam. This case demonstrates how mechanized fabric can achieve precision and efficiency that traditional processes cannot match on complex curved structures.
Engineering difficulty: Millimeter level requirements on curved surfaces
This 42 year old gravity dam requires the addition of a 40-60cm thick reinforced concrete layer on the upstream slope. Construction faces three major challenges:
There is a 0.5% longitudinal slope variation on the 240 meter long dam surface
Design requirements: The thickness error of the steel mesh protective layer should be ≤15mm
The daily temperature difference on the plateau reaches 25℃, and the setting time window of concrete is short
Equipment array - Three machine collaborative operation
The project adopts a ‘one main and two auxiliary’ arm frame fabric system:
- Main equipment : 48meter arm frame fabric machine covering a 160 meter area in the middle of the dam body
- Auxiliary equipment: Two 32 meter boom devices, responsible for 40 meter areas at each end
- Key technology: Three devices share an intelligent control system to achieve synchronous pouring parameters
Practical Record - Precise Dance on Curved Surfaces
Phase 1: Parameter Calibration
On the first day, only the construction of the 30 meter test section was completed. Engineers have identified two key issues:
When the slump of concrete is 180mm, a slip of 5-8mm/s occurs on the slope surface
Conventional continuous pouring leads to excessive lateral pressure on the formwork
Solution
- Adjust the concrete mix proportion to control the slump at 160±10mm
- Adopting the ‘jumping interval pouring method’, with each compartment length not exceeding 6 meters
- Develop slope compensation algorithm, with the end of the boom automatically adjusting the angle according to the slope of the dam surface
Phase 2: Full Speed Propulsion
After parameter optimization, the three devices entered an efficient collaborative state:
- The main equipment arm moves at a constant speed of 0.3m/s, and the end hose is always 15-20cm away from the template
- The auxiliary equipment adopts a symmetrical pouring sequence to reduce uneven stress on the formwork
- Set up an induction seam every 40 meters to perfectly control temperature stress
The most ingenious operation occurs at the curved turning section of the dam body. The operator enables the ‘surface tracking mode’, and the boom system automatically adjusts the pouring trajectory according to the preset surface equation, achieving an accuracy of only 9.2mm in the standard deviation of the protective layer thickness on an arc surface with a radius of 85m.
Quantitative Comparison - Proof of the Advantages of Mechanized Fabrics
Technological Innovation Points
Dynamic pressure compensation system
The pressure sensor equipped with the equipment can detect the template side pressure in real time, and automatically reduce the pumping speed when the value approaches the threshold, successfully controlling the maximum side pressure within 85% of the design value.
Plateau adaptation transformation
In response to the environmental characteristics at an altitude of 3200 meters, the equipment has been equipped with a hydraulic oil cooling system and an engine intake compensation device to ensure continuous operation stability.
Digital Twin Preview
Before construction, a full process simulation was conducted using a BIM model to identify and resolve 7 potential collision and interference nodes in advance.
Expand application value
The technical solution formed by this project has generated spillover effects:
Standardization of restoration of old dam bodies
The summarized ‘plateau dam surface reinforcement method’ is being applied to the reinforcement projects of the other three reservoirs.
Equipment function upgrade
Based on the data of this project, the equipment manufacturer has developed a ‘special mode for hydropower engineering’, which has added intelligent functions such as seepage pressure monitoring avoidance and grouting pipe reservation.
Cost reconstruction
Although the equipment rental cost is relatively high, the compensation for reduced storage capacity loss by shortening the construction period amounts to 2.3 million yuan, saving an overall project cost of 17%.
Engineering Philosophy - From ‘Pouring’ to ‘Weaving’
Li Zhenggao, the chief engineer of the project, said at the summary meeting, ‘ This construction has given us a new understanding of concrete pouring-it can be a precision manufacturing process full of mechanical aesthetics. Arm frame fabric equipment is not just a replacement for manual labor, it brings an improvement in the dimension of engineering quality.
When the reservoir began to refill, monitoring data showed that the stress distribution uniformity of the newly reinforced layer increased by 34% compared to the original design. This case proves that in the field of infrastructure maintenance, the value improvement brought by refined construction goes far beyond efficiency figures. Every precise fabric is injecting new vitality into these ‘elderly’ water conservancy facilities.
