Modular Spatial Steel Mesh Prefabricated Support Technology for Underground Engineering
Aiming at the problems of large excavation space,long exposure time,and easy occurrence of safety accidents due to the deterioration and deformation of surrounding rock in mechanized construction of underground space,a new type of spatial steel mesh structure suitable for supporting underground tunnels is proposed,and on-site testing and application are carried out in the Panyu Square underground tunnel of Guangzhou Metro.A spatial steel mesh structure with a high-strength seamless steel pipe as a main stress piece and a π-shaped reinforcement and a U-shaped reinforcement as an erection piece,wherein the unit module components are connected by welding,and the structural modules are connected by flange high-strength bolts.The field application results show that:(1)the prefabricated steel mesh structure is safe and reliable,the process is feasible,it can be prefabricated in the factory and quickly disassembled and assembled in the field,compared with the traditional I-beam assembly,the work efficiency is increased by 66%,the time of forming support stress is increased by 90.5%,the maximum settlement deformation of the vault is reduced by 32.9%,and the maximum convergence value of the periphery is reduced by 33.6%,the maximum ground settlement deformation value is reduced by 31.5%.(2)The measured stress values of steel pipes in various parts during the operation of the structure are far lower than the yield strength of Q420 steel.The new spatial steel mesh support structure can quickly form the support capacity,effectively inhibit the deformation of surrounding rock,and the stress deformation of the structure is reasonable.
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