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Reasons for the damage of the support structure of SDS tunnel jet fan

The main factors that cause the support structure load of the jet fan to fail to meet the specification requirements are as follows:

(1) The concrete pouring in the arch is not compact enough, resulting in a loss of bond between the embedded parts and the concrete;

(2) The second lining of the arch is detached from the initial support, and even voids appear. When the jack is placed between the test frame for processing the support and the concrete at the top of the tunnel, it causes the concrete at the top of the tunnel to break after loading, making it impossible to load to the required load according to the specifications;

(3) The pre embedded steel plate and pre embedded steel arch of the tunnel fan were not connected according to the design requirements, and did not form a whole with the pre embedded steel arch. The welding quality of the steel plate and steel reinforcement was not up to standard, and the number of connecting steel reinforcement after pre embedded steel plate was cut and did not meet the design requirements;

(4) The welding quality of the fan support structure is not up to standard and does not meet the design requirements.

During the load test of the tunnel fan support structure, the factor that often causes the detection to fail is the poor quality of the pre embedded steel plate construction. Due to the installation of pre embedded steel plates during the early stage of civil construction and insufficient connection with the later stage of tunnel mechanical and electrical construction, the importance of pre embedded steel plates was overlooked during civil construction, which did not meet the design requirements and ultimately led to insufficient bearing capacity.

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