Research on the Mechanical Response Law and Support Parameter Optimization of Tunnel Mechanized Construction
The over excavation generated after tunnel excavation is usually backfilled with shotcrete,resulting in differences between the actual thickness and the design thickness of the initial support.Therefore,it is necessary to study the mechanical response law of mechanized construction of large section tunnels under over excavation conditions.Based on different levels of surrounding rock,the paper establishes calculation models for the maximum,minimum,and average over excavation rock surface contours to analyze the deformation,stress,and initial support stress of surrounding rock under over excavation conditions,and compares the on-site monitoring data with the initial support design thickness to obtain the mechanical response law of mechanized construction of large section tunnels.Due to the over excavation,the initial support thickness is larger than the design thickness,and for the consideration of construction economy and construction progress,the paper analyzes and concludes that the initial support of different surrounding rocks under different working conditions is in a smaller range of the maximum tensile stress of the borehole,through checking and calculating the safety factor of initial support,the optimal initial support parameters that meet the safety requirements for different surrounding rock conditions are put forward.
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