节理岩体对盾构开挖稳定性和地层损失率的影响

Effects of Jointed Rock Masses on Stability of Shield Tunnels Under Tunnelling and Ground Loss Rates

为研究节理岩体对盾构隧道开挖稳定性和地层损失率的影响,以南昌某盾构隧道为研究对象,采用离散元软件UDEC建立数值模型,分析节理倾角对围岩变形和地表沉降的影响规律,通过拟合得到地层损失率,并将模拟值与实测值进行对比,研究节理间距、盾构隧道间距以及隧道埋深对地表沉降的影响规律。研究结果表明:盾构隧道围岩在节理面产生较大位移,节理倾角的存在导致隧道围岩产生偏压现象,节理倾角为60°、90°时容易失稳;当节理倾角为60°时,地表沉降取得最大值,当节理倾角为45°时,地表沉降取得最小值。通过拟合Peck曲线可知,该工程区段的地层损失率范围为0.658%~0.896%;地表沉降值与隧道埋深、隧道间距以及节理间距均成负相关。

To explore the influence of joint rock masses on the stability of tunnels under tunnelling and the ground loss rates, taking the tunnel in Nanchang as a research object, the numerical model was constructed by the discrete element software UDEC. The influence of inclined joint angles on surrounding rock deformation and subsidence was analyzed, and the ground loss rate was obtained by fitting. The simulated values were compared with the measured values in order to study the influence of joint spacing, shield tunnel spacing and tunnel buried depth on subsidence. According to the actual project, a large displacement of surrounding rock of the tunnel occurred at the joint surface, and the existence of dip angles led to the eccentric compression phenomenon of rock around the tunnel. When the dip angle was 60° and 90°, it was prone to lose stability. The maximum value of subsidence occurred when the dip angle was 60°, and the minimum value occured when the dip angle was 45°. According to the Peck curve, the ground loss rate of the project section ranged from 0.658% to 0.896%. The subsidence was in negative correlation with buried depth, tunnel spacing and joint spacing.