采用总安全系数法对几个隧道设计问题的探讨

Exploration on the Several Problems of Tunnel Design with the Total Safety Factor Method

研究目的:目前复合式衬砌支护参数的设计以工程类比法为主,无法得出安全系数,因而设计施工中经常对锚杆设置、隧道承载主体、支护参数优化等问题存在争议。本文采用总安全系数法对这些争议问题进行探讨,并提出相关建议。研究结论:(1)因实测锚杆轴力小而少设或不设锚杆,会降低结构的总安全系数;目前采用的砂浆锚杆耐久性不足,仅对施工阶段和运营初期的安全性有作用;如采用耐久性锚杆,则大部分隧道的喷层厚度可减少;(2)在满足施工和运营总安全系数的前提下,复合式衬砌可以有多种设计方案,且初期支护、二次衬砌都是承载主体,最为合理的方案除考虑经济性、耐久性等因素外,还应保证喷层与二衬具有合理的强度匹配;(3)建议根据地层条件、埋深、地下水发育情况进行支护参数的优化;(4)本研究成果可为隧道优化设计提供思路和方法。

Research purposes:At present,the design of support parameters of composite lining is mainly based on engineering analogy method,so the concrete safety factor cannot be obtained,and there are often several controversial issues such as the bolts setting,tunnel bearing main body and parameter optimization in the design and construction.In this paper,these controversial issues are discussed by the total safety factor method,and relevant suggestions are proposed. Research conclusions:(1 )If there are few or no bolts setting in the tunnel because of the small test axial force,the total safety factor will be reduced,and the durability of the bolts currently used in the groundwater development area is insufficient,which only plays a role in the safety of the construction stage and the initial operation period.If guaranteeing the durability of the bolt ,the thickness of the shotcrete layer can be reduced appropriately.(2)On the premise of satisfying the total safety factor of construction and operation,the composite lining can be designed in many schemes,and primary support and secondary lining are both the main bearing bodies.And the most reasonable scheme should not only take into account economic and durability,but also ensure that the shotcrete layer and the secondary lining have reasonable strength matching.(3)It is suggested to divide the supporting parameters according to geological conditions,buried depth and groundwater developmental condition.(4)The research results can provide ideas and methods for tunnel optimization design.