隧道衬砌开裂机理及加固措施研究

Study on Cracking Mechanism and Reinforcement Measures of Tunnel Lining

黏性土具有可塑、膨胀和收缩等显著特点,易诱发衬砌开裂破坏。结合具体工程案例,对隧道仰拱破检段进行含水率试验和钎探试验以及钻探验证,得到了黏性土层承载力强度、含水率大小及分布情况,初步总结了衬砌裂缝特征规律。根据监测数据和数值模拟综合分析结果,分析了裂缝的形成机理并验证了裂缝特征规律。结果表明:仰拱底部软弱层与隧道沉降和仰拱开裂的相关性非常显著;仰拱底部软弱层易导致隧道发生不均匀沉降;横向的不均匀沉降易导致仰拱填充层出现斜向、纵向裂缝;纵向的不均匀沉降易导致二衬出现环向裂缝。根据研究结果针对性地提出了加固方案,并设计了注浆孔注浆类型、方式和钢化管的尺寸、间距和排列方式。现场结果反馈表明,加固措施具有良好的加固效果。

Viscous soil has obvious characteristics such as plasticity, expansion and shrinkage, and it is easy to induce cracking damage of lining. Combined with the specific engineering case, the water content test, brazing test and drilling verification of the tunnel inverted arch inspection section were carried out, and the bearing strength, water content and distribution of the clay soil layer were obtained, and the characteristics of the lining crack characteristics were preliminarily summarized. According to the comprehensive analysis results of monitoring data and numerical simulation, the formation mechanism of cracks was analyzed and the characteristics of cracks were verified. The results show that the correlation between the weak layer at the bottom of the invert arch and the tunnel settlement and the inverted arch crack is very significant;the weak layer at the bottom of the invert is easy to cause uneven settlement of the tunnel;the lateral uneven settlement tends to cause the inverted layer to appear oblique and longitudinal cracks;longitudinal uneven settlement is likely to cause circumferential cracks in the second lining. According to the research results, the reinforcement scheme is proposed in detail, and the grouting type, mode and size, spacing and arrangement of the tempering tube are designed. Field results feedback shows that the reinforcement measures have a good reinforcement effect.