软岩中TBM停机状态下岩机相互作用规律研究

Interaction law between shield and rock under TBM shutdown in soft rock

在软岩环境下使用TBM施工时,遇卡机等事故处理和设备检修更换常需TBM停机,预留变形量和停机时间是TBM安全运行的关键。依托白龙江引水工程六盘山泥岩隧洞,根据实际地质条件、隧道结构和TBM施工流程,采用数值计算的方法研究了TBM停机状态下围岩的变形特征及其与护盾的相互作用,并分析了合理的预留变形量和停机时间。结果表明:①该工程砂质泥岩为极软岩,流变性显著且服从Cvisc和Burgers模型,预留足够的变形量和快速掘进可保证TBM安全通过;②在停机期间,围岩变形具有显著时空效应,变形先快后慢,垂直位移大于水平位移,护盾后部围岩位移大于前部;③岩机相互作用的时空效应表现为,自下而上、由后至前,相继经历无接触-局部接触-完全接触-强烈挤压的过程;④预留变形为10 cm时的TBM安全停机时间不宜超过7 d。研究成果对认识软岩中TBM停机期间岩机相互作用具有理论参考意义。

When TBM is used for construction in soft rock environment,TBM shutdown is often required in case of accidents such as jamming or equipment maintenance and replacement.Reserved deformation and shutdown time are the key to the safe operation of TBM.Based on the Liupanshan mudstone tunnel of Bailong River diversion project,according to the actual geological conditions,tunnel structure and TBM construction process,the deformation characteristics of surrounding rock and its interaction with shield under TBM shutdown were studied by numerical calculation method,and the reasonable reserved deformation and shutdown time were analyzed.The results showed that:①The sandy mudstone in the project was extremely soft rock with significant rheology and conforms to the CVisc and Burgers models.Sufficient reserve margin and rapid excavation could ensure the safe passage of TBM.②During the shutdown period,the deformation of surrounding rock had a significant time-space effect.The deformation was fast at first and then slow.The vertical displacement was greater than the horizontal displacement,and the displacement of surrounding rock in the shield rear was greater than that in the front.③The space-time effect of rock-shield interaction was manifested as a process of non contact-local contact-complete contact-strong extrusion from bottom to top and from back to front.④The safe shutdown time of TBM with reserved deformation of 10 cm should not exceed 7 days.The research results have theoretical reference significance for understanding the rock-machine interaction during TBM shutdown in soft rock.