What are the technologies for saving tunnel concrete? In tunnel engineering, in order to reduce the cost of the project, reduce resource waste, and meet the requirements of structural safety and durability, a variety of technologies are usually used to save the amount of concrete. The following is a detailed introduction to several common technologies and methods for saving tunnel concrete:

   1. Optimize concrete mix ratio

   Select high-quality raw materials:

   ① Cement: Select cement with low hydration heat and low alkali content, control the fineness and specific surface area of cement, and reduce the amount of cement on the basis of ensuring strength. It can reduce costs and improve the durability and stability of concrete.

   ② Aggregate: Select well-graded and hard aggregates, control the particle size and gradation of aggregates, so that they can form a tight stack in concrete, improve the working performance and strength of concrete, and reduce the void ratio of concrete, thereby reducing the amount of concrete to a certain extent.

   ③ Admixtures: Adding high-efficiency water reducing agent, retarder and other admixtures can improve the working performance of concrete, reduce the water-cement ratio and water consumption while maintaining the fluidity of concrete, thereby reducing the shrinkage rate of concrete, improving durability, and also helping to save concrete.

   Adding mineral admixtures: Adding fly ash, slag and other mineral admixtures in appropriate amounts can improve the working performance of concrete, partially replace cement, reduce the amount of cement used and reduce costs without reducing the strength of concrete, and at the same time improve the impermeability and other properties of concrete.

   2. Adopting advanced construction technology

   ① Self-filling lining construction system: The system developed by Sato Industry in Japan adopts self-filling concrete injection technology, which can directly fill concrete to the top of the tunnel without vibration and pipeline switching. Through improvements in the sliding arch equipment and structure, the left and right automatic balance of concrete pouring height is achieved, which improves construction efficiency while accurately controlling the amount of concrete to avoid waste.

   ② Arm-type concrete placing machine and 360-degree periscope pouring device: The arm-type concrete placing machine is equipped on the trolley, which can increase the number of feeding layers from the arch line to the arch top, realize the full coverage of the arch under pressure, and shorten the concrete flow distance. The 360-degree periscope pouring device has telescopic and rotation functions and can be remotely controlled. It changes the problem that the traditional arch pouring method cannot control the pouring direction and flow rate, effectively eliminates the cofferdam phenomenon, greatly reduces the probability of arch voids, improves the quality of concrete pouring, and reduces the amount of secondary concrete filling caused by voids and other problems.

   ③ Wet spraying trolley spraying technology: The wet spraying trolley integrates multiple functions such as pumping, spraying, walking, and remote control. The operator can remotely control the spraying arm, adjust the spraying position and nozzle angle, effectively reduce the dust and concrete rebound phenomenon in the tunnel, and reduce the concrete rebound rate to less than 10%, greatly reducing the waste of materials.

   3. Accurate construction management and design

   ① Accurate calculation of engineering quantity: Use BIM and other technologies to establish a three-dimensional model of the tunnel, accurately calculate the tunnel excavation profile and concrete pouring volume, provide accurate basis for material procurement and construction, and avoid excessive purchase of concrete causing waste.

   ② Optimize tunnel design: Under the premise of meeting the tunnel's functional and safety requirements, optimize the tunnel's structural design, such as reasonably determining the lining thickness and shape. For areas with good geological conditions, the lining thickness can be appropriately reduced; new tunnel structure forms, such as partially assembled structures, can be adopted to reduce the amount of concrete poured on site.

   ③ Strict construction process control: Strengthen management during the construction process, formulate strict concrete pouring operating procedures, ensure the continuity and uniformity of concrete pouring, and avoid problems such as leakage and mold running that lead to concrete waste. At the same time, strictly control the transportation process of concrete to prevent segregation and water seepage during transportation, which affects the quality and usable amount of concrete.