引水隧洞复合支护钢拱架变形特性及围岩稳定性研究

 为研究复合支护中钢拱架变形特性和力学机制，优化支护参数，保证引水洞室的稳定性，在对支护结构进行力学分析的基础上，采用数值计算方法对山西引水工程中施工支洞进行了仿真模拟。基于复合支护力学作用机制的研究，分析钢拱架在初期支护中的应力及变形特性，并结合工程实例研究复合支护中钢拱架、钢筋网以及喷层所分担的围岩压力比例。数值计算表明：与普通的喷锚支护相比，有钢拱架的复合支护体系能够对围岩变形提供直接支护力，使围岩初期变形和塑性区范围大大减小，有利于围岩承载拱的形成并发挥其自身承载能力，同时其他各支护材料的变形和应力也有较大程度的降低，是洞室破碎围岩支护的有效手段之一。研究成果为山西省中部引黄工程引水洞支护设计提供了理论依据，对同类工程也具有借鉴和指导意义。

STUDY OF DEFORMATION CHARACTERISTICS OF COMPOUND SUPPORT STEEL ARCH AND SURROUNDING ROCK STABILITY IN DIVERSION TUNNEL

To study the deformation characteristics and mechanism of compound support steel arch，optimize the support parameters and ensure the stability of diversion tunnel，the tunnel construction in Shanxi water diversion project is simulated numerically based on the mechanical analysis of the support structure. According to the action mechanism of the compound support，the stress and deformation characteristics of steel arch during primary supporting are analyzed. Combined with field project，the pressures that surrounding rock act on steel arch，reinforcing mesh and shotcrete are calculated，and the shared ratio of pressure for every kind of support is given. The numerical calculation shows that，the compound support with steel arch，compared with conventional shotcrete support，can provide direct resistance to surrounding rocks；and the primary deformation and plastic zones of surrounding rocks can be reduced significantly. This will facilitate the formation of rock arch and increase the bearing capacity of compound support；meanwhile，the deformation and stress of the support materials can be reduced greatly. The research results provide theoretical basis for support design of the diversion tunnel for the Yellow River diversion project in the middle part of Shanxi province. This is an effective support method for fractured surrounding rocks；and they also have important reference and guiding significance for similar tunnels.