TBM隧洞倾斜黏结锚杆受力特性分析及支护参数优化

Mechanical Characteristics Analysis and Support Parameter Optimization of Inclined Bonding Bolt in TBM Tunnel

依托北疆供水二期输水KS隧洞工程,针对敞开式TBM隧洞倾斜黏结锚杆设计了三角形带孔垫板,通过现场监测锚杆轴力进行锚杆受力特征研究,同时结合数值模拟进行对比分析,并对锚杆支护参数进行优化设计,研究结果表明:隧洞轮廓边缘锚杆近端轴力逐渐增大,在中性点(0.5 m)附近达到峰值,往锚杆远端处轴力逐渐减小.锚杆轴力最大值为3.48 kN,应力为7.09 MPa,应力比仅为0.030.隧洞不同位置处锚杆轴力有所差别,总体表现为拱顶处锚杆轴力最大,拱肩处次之,拱腰处最小.锚杆轴力计算值与实测值两者变化规律基本一致,但总体上计算值比实测值稍大,主要是由于现场测试时围岩已经发生位移,而且锚杆实际工作中锚固体部分产生一定滑移,造成实测值较低.综合分析建议锚杆长度从3.0 m减少到2.5 m,纵向间距从1.0 m增加到1.2 m,环向间距为1.0 m,梅花形布置,不仅可以减少施工周期,而且可以降低施工成本,具有较大的经济效益.

Based on the KS tunnel project of the second phase water supply project in Northern Xinjiang,the triangular bearing plate with hole is designed for the inclined bonding anchor rod of open TBM tunnel. The stress characteristics of the anchor rod are studied by monitoring the axial force of the anchor rod on site. At the same time,the comparative analysis is carried out combined with numerical simulation,and the bolt support parameters are optimized. The research results show that the axial force at the near end of the bolt at the edge of the tunnel contour gradually increases. It reaches the peak value near the neutral point(0.5 m),and the axial force decreases to the far end of the bolt. The maximum axial force is 3.48 kN,the stress is 7.09 MPa and the stress ratio is only 0.030. The axial force of anchor rod at different positions of tunnel is different. The axial force of anchor rod at vault is the largest,followed by arch shoulder and arch waist. The calculated value of bolt axial force is basically consistent with the measured value,but on the whole,the calculated value is slightly larger than the measured value,which is mainly due to the displacement of surrounding rock during the field test and the sliding of anchor solid part in the actual work of bolt,resulting in the lower measured value. Through comprehensive analysis,the length of anchor rod is reduced from 3.0 m to 2.5 m,the longitudinal spacing is increased from 1.0 m to 1.2 m,and the circumferential spacing is 1.0 m. The plum shaped arrangement can not only reduce the construction period,but also reduce the construction cost,which has great economic benefits.