Study on Optimization of Construction Plan for Soft Rock Large Span Section of Tunnel
The construction of super large section soft rock tunnels is prone to causing instability and collapse of the surrounding rock.In order to reduce construction risks,short footage,weak blasting,multi-step excavation,and strengthened support are generally adopted in engineer-ing.However,the design tends to be conservative,which is uneconomically and delayed construction period.Based on the Zhangjiashan tun-nel,this paper analyzes the advantages and disadvantages of the original 25 m long span double-sided wall heading method construction scheme and its support system from the aspects of engineering investment and construction period.Combined with engineering analogy,the original scheme is optimized and designed.The optimized monthly progress is twice that of the original scheme,which can save 9.3 months of construc-tion period.The research results can provide reference value for similar projects.
Soft rock tunnelExtra large cross-sectionLarge span section
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