Removal of reinforced concrete internal support beams in deep foundation pits: Which method is the best?
Thread Content
Reinforced concrete internal supports are support systems cast in place within deep foundation pits; their layout and design are largely not constrained by the planar shape of the pit. They can withstand both compressive and tensile forces, and possess advantages such as high stiffness, low deformation, good integrity, and relatively simple construction techniques, which enables their wide range of applications. Currently, the removal of concrete internal supports in deep foundation pits is generally carried out using methods such as open blasting, manual demolition, static blasting, and cutting. Each of these removal methods has its own advantages, disadvantages, and suitable application scenarios. In actual construction, it is necessary to choose the appropriate method for removing the supports based on the specific conditions of the project, which can enhance both the safety and efficiency of such demolition work. 01 Demolition using explosive charges: This method is generally used for the demolition of large-scale reinforced concrete internal supports. An impact drill is used to drill holes in the concrete support beams according to the designed hole pattern, explosives and millisecond detonators are inserted, and the area is cleaned up after blasting. The advantages of explosive demolition are its high efficiency, short construction time, and ease of cleanup ； The disadvantages are that blasting generates vibration, flying debris, significant dust, and loud noise, which have a certain impact on the surrounding area. Mingbao demolition process: Setting up safety protection nets → Drilling → Loading explosives → Initiating the explosion → Cutting rebar → Cleaning up concrete debris.
02 Manual demolition: This involves assembling a certain number of workers who use mechanical equipment such as sledgehammers and pneumatic hammers to break up reinforced concrete beams into sections, then cutting the rebar and removing and transporting the concrete blocks. Using manual crushing results in low construction efficiency, long project durations, high noise levels, and significant dust generation, causing pollution to the surrounding environment. It also has a considerable impact on the occupational health of workers. 03 Static Blasting: Static blasting involves drilling holes in reinforced concrete support beams according to the designed hole pattern. After drilling, a static expansion agent is poured in; the expansion of this agent causes the concrete to crack. Finally, the cracked concrete is removed using pneumatic hammers, and the rebar is cut out manually. Its construction method is relatively simple, and it has advantages such as less dust and lower noise. The drawback is that expanders are harmful to the human body, and the construction progress is slow. 04 Cutting and removal: Rope saw cutting is further divided into rope saw cutting and disc saw cutting; both methods are used to cut reinforced concrete support beams into smaller sections, which are then lifted and removed using cranes. The difference is that rope saw cutting uses high-strength diamond cutting wires, while disc saw cutting employs diamond discs. This demolition method can be combined with internal support force analysis to plan the locations for segmented cutting in advance; it features smooth and even cut surfaces, low noise, no vibration, no dust generation, no exhaust pollution, and efficient and safe construction.
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