复杂条件下隧道断面形状和支护参数优化

通过有限差分法（FLAC3D）数值计算和现场试验对马蹄形断面和大曲率边墙、似圆形断面形式下隧道的支护受力和围岩变形特征进行了对比分析，得出采用似圆形断面可以有效地控制围岩的变形量和变形速率，尤其是水平收敛变形；现场变形量测时的丢失位移所占总位移比例较大，其中下台阶丢失位移比例最大；通过现场试验，对不同支护刚度下围岩压力、锚杆受力、钢架、混凝土应力以及二次衬砌分担的围岩压力和模筑混凝土受力情况进行分析，结合洞室变形的现场量测，得出二次衬砌接触压力及分担围岩压力比呈现出随着初支刚度增大而增大的规律，并综合确定了板岩段合理的支护参数。该结论对在构造应力发育的软岩地区修筑隧道提供了有益的工程经验

Optimization of section shape and support parameters of tunnel under complicated conditions

Numerical simulation (FLAC3D) and field experiments are used to study the shape effect of tunnel section. Stress of primary support and tunnel deformation under horseshoe-shaped section and large curvature wall, quasi circle-shaped section are analysed and compared. Numerical simulation and field measurement indicat that deformation and deformation rate of surrounding rock under quasi circle-shaped section could be effectively lessened, especially convergence of side wall, compared with that under horseshoe-shaped section. Ratio between lost displacement while measuring in-site and total displacement of surrounding rock is large, and the lost ratio of lower bench is largest. Field experiments of different support stiffnesses are conducted. It is measured and analysed that pressure of surrounding rock mass, axial force of anchor, stress of steel frame and stress of shotcrete under different primary support parameters. Also the contact pressure shared by secondary lining and the stress of mode concrete under different primary support stiffnesses are measured and analysed. Deformation of tunnel under different support stiffnesses are also measured. It is concluded that the contact pressure of secondary lining and pressure ratio shared by secondary lining increae with support stiffness increase. And suitable support form is synthetically determined. That would offer valuable practical experience to tunnelling in soft rock mass with high tectonic stress-field.