隧道软弱围岩挤压大变形非线性流变力学特征及其锚固机制研究

介绍围岩大变形的工程实例、隧道围岩挤压性大变形的定义及其工程特征。系统总结国际上隧道围岩挤压性大变形的3种预测方法,即:经验法、半经验半理论法和试验判定法。将Hoek(1999)对围岩挤压大变形的预测和判定方法(半经验半理论法)应用于乌鞘岭隧道岭脊段F7断层带开挖施工中的围岩稳定性判别,并对这种预测方法进行了可靠性评价,认为有支护情况下比无支护情况下变形预测失效概率要小得多,也就是说毛洞围岩变形收敛率的大小更难以掌控。介绍作者团队对隧道围岩挤压性大变形问题按三维非线性流变的理论分析、相应专用软件的研制;并将理论研究计算成果与现场实测数据进行对比,结果按大变形三维问题的计算值比按小变形二维平面问题的计算值更接近工程实际;同时,指出了有待进一步深化研讨的若干问题。最后,提出了管控/约束隧道围岩大变形持续发展的锚固技术措施--一种新型大尺度让压锚杆/预应力长锚索,分析其机制和优势,介绍其构造类型,并提出下一步的研究思路。该方法已在几处工地不同程度地成功实施,取得了应有的经济效益和技术成果。

Study on Non-linear Rheologic Mechanical Property of Squeezing Deformation of Soft Surrounding Rock in Tunneling and Its Anchorage Mechanism

The project cases, definition and engineering property of huge deformation of surrounding rocks are presented; 3 worldwide commonly used prediction methods for squeezing deformation of surrounding rocks, i.e., empirical prediction method, semi empirical prediction method and trial testing method, are systematically summarized. The prediction method for the squeezing deformation of surrounding rocks proposed by Hoek in 1999 (semi empirical semi theoretical prediction method) is used to evaluate the stability of the surrounding rocks of F7 fault of ridge section of Wushaoling tunnel, the reliability of the prediction method is assessed and conclusion is drawn as follows: the probability of the deformation prediction failure of supported tunnels is much smaller than that of unsupported tunnels, that is to say, the magnitude of the convergence of the surrounding rocks of unsupported tunnels is more difficult to be controlled. The theoretical analysis on the squeezing deformation of the surrounding rocks of tunnels by means of 3 D non linear rheology made by the authors, as well as the development of the corresponding software, are presented; and the calculated result is compared with the measured results, which shows that the result calculated according to the 3 D mode of the huge deformation is more close to the field conditions than that calculated according to the 2 D mode of the small deformation. Finally, a new type of large scale yielding rock bolt/prestressed anchor cable is proposed to control the development of the huge deformation of the surrounding rock of tunnels; the mechanisms and advantages of the new type of large scale yielding rock bolt/prestressed anchor cable are analyzed, the structures and types thereof are presented, and the concept of future researches are provided; the new type of large scale yielding rock bolt/prestressed anchor cable has been successfully applied in several projects and good economic and technical results have been achieved.