为清晰完整地认知隧道围岩大变形,方便后续的深入、具体研究。基于既有研究内容,将具有明显时间效应和塑性变形,产生的变形超过了规范允许的变形量且严重影响隧道工程的正常使用,最终导致隧道丧失整体结构稳定性的围岩变形现象定义为隧道围岩大变形;从变形成因角度重新划分隧道围岩大变形的类型为:
膨胀型、高地应力软岩型、黄土型、高地温型和复合型;归纳总结不同类型隧道围岩大变形的变形机制、本构模型、支护理论等,并总结针对不同类型围岩大变形现象采取的控制措施和施工方法。在此过程中,针对存在的不足提出未来可能的发展趋势: 1)完善隧道围岩大变形机制,并通过现场检测、模型试验与有限元分析模拟总结出隧道围岩大变形规律以及受力特点,为工程实践提供科学依据,实现大变形的精确支护。2)统一不同类型的隧道围岩大变形分级控制措施。由于工程的多变复杂和特殊性,难以总结出普适性的大变形分级控制措施,但基于大量的隧道围岩大变形案例,制定出不同类型隧道的围岩大变形分级控制措施依然具有很高的工程参考价值。
A clear and systematic cognition of large deformation
of tunnel surrounding rock is important for the further and specific research.
Based on the existing research, large deformation of tunnel surrounding rock is
defined as the deformation phenomenon, with obvious time effect and plastic
deformation, exceeding the allowable range of specification and having
seriously effects on the normal usability of tunnel engineering and even
ultimately leading to the loss of the overall structural stability of tunnel.
From the angle of deformation origin, the types of large deformation of tunnel
surrounding rock are reclassified to expansion type, high ground stress soft
rock type, loess type, high ground temperature type, and compound type. The
deformation mechanism, constitutive model and supporting theory of large
deformation of various surrounding rock types are summarized, and the control
measures and construction methods are taken for different types of large
deformation of surrounding rock. In this
process, it was found that there are still some deficiencies, and possible
future development trends are put forward: (1) The mechanism of large
deformation of tunnel surrounding rock will be improved, and the law of large
deformation and stress characteristics of tunnel surrounding rock are
summarized through field detection, model test and finite element analysis and
simulation, which can provide scientific basis for engineering practice and
achieve accurate support of large deformation. (2) The classification control
measures for large deformation of surrounding rock of different types of
tunnels are unified. Due to the variety, complexity, and particularity of the
project, it is difficult to summarize the general control measures for all
types of large deformation of surrounding rock of various tunnels. However,
based on a large number of large deformation cases, the formulation of control
measures for specific large deformation type of different types of tunnels
still has high engineering reference value.