盾构隧道收敛与病害特征及性能相关性研究

基于南京地铁3号线九龙湖站—诚信大道站区间隧道收敛长期监测数据及结构检测成果,通过对收敛形态、数据与结构病害、性能的统计和指标分析获得以下研究结论:(1)隧道管片椭圆收敛形态主要以水平向“外扩型”为主,其长轴方向与水平线偏转角多处于±1～±30°之间;(2)收敛数值与裂缝数量、渗漏面积成正相关,但是与结构强度、错台量及壁后空鼓无明显相关性;(3)软土地层隧道收敛值＞60 mm时,管片纵向贯通裂缝数量明显增多,且最大宽度已达到或超过设计标准值0.2 mm。建议在软土条件下钢环加固标准设置为60 mm;(4)管片渗漏部位常发生于隧道水平线附近±30°范围,这与“外扩型”收敛椭圆长轴方向产生最大变形量Δ_max的范围相一致,进一步验证了收敛变形是导致接缝渗漏的主要成因。

Study on the Correlation between Convergence and Structural Damage Characteristics and Performance of Shield Tunnels

The study is based on the long-term monitoring convergence data and the detection results of the structural state of Nanjing Metro Line 3 JiuLonghu～ChengXin Avenue tunnels. The study conclusions are obtained statistically and analytically for convergence forms, data, and structural diseases and performance indicators. The convergence form of an elliptic tunnel segment is a horizontal expansion type, and its long axis direction and horizontal deflection angle are between ±1°～±30°, respectively. The tunnel convergence is correlated with the number of cracks and leakage area. However, it has no obvious correlation between the structural strength, the amount of stagger, and the holes behind the lining. When the tunnel convergence value in soft soil layer is greater than 60mm, the longitudinal through cracks increases significantly, and the maximum width reaches or exceeds 0.2mm. It is suggested to use steel ring reinforcement for the shield tunnel when convergence reaches 60mm in the soft soil layer. Joint leakage is mostly caused by segment converging deformation, which is further confirmed by the fact that segment leakage usually occurs in the range of ±30° along the horizontal tunnel line. This range is comparable with the maximum deformation δ_max along the long axis of the converging ellipse of the "outward-expanding type."