炎热多雨环境下膨胀围岩隧道施工的时变力学性态研究

Swelling rock is a kind of geology body, which has abundant crack and remarkable swell-shrink characteristic.Swelling rock will collapse and become soft when meets water which makes the stability of round the rock sharply descends and course the construction difficulty and risk of the tunnel engineering biggest，particularly in rainy and hot environment . But few related research result, weak base of theories research is very disproportionate to booming development practice. Based on the construction monitor and large proportion model test, adopting to elastoplastic theory and finite element method, the viscosity characteristic and the timespace effect of stress and displacement of swelling stock is studied under the dry-wet circulating condition. Then the expansion-rheology model of swelling rock will be build up. And planar model that based on the elastoplastic theory and finite element method, and elastoplastic yield criterion of tunnels in swelling rock will be build up.Adoptting a finite element method software, the dig process of tunnels in swelling rock under various construction condition will be studied, in order to discovery the stress-strain relationship and the reciprocity mechanism between swelling rock and tunnel ling.According to experiment a data to invert the mechanics parameter of swelling rock, and discovery methods to control the transform of swelling rock and methods how to reinforce the swelling rock, and then provide theories basis for structural design and construction optimization of tunnels in swelling rock.

膨胀岩是一种多裂隙且有显著胀缩性的地质体。膨胀岩遇水后膨胀变形、崩解软化，围岩稳定性急剧下降，导致隧道工程的施工难度和风险极大，尤其在炎热多雨环境下隧道开挖过程中膨胀岩与支护结构之间的相互作用机理极为复杂，而国内外相关研究成果很少，薄弱的理论研究和蓬勃发展的工程实践极不相称。 本项目拟采用弹粘塑性理论和有限元法基本理论，在依托工程的长期施工监测和大比例物理相似模型试验的基础上，研究炎热多雨环境下不同干湿循环条件时膨胀围岩的粘滞特性、膨胀围岩应力和位移的时空效应，建立膨胀围岩的膨胀-流变模型；建立膨胀岩隧道平面弹粘塑性有限元模型以及弹塑性屈服准则；采用有限元软件，对膨胀围岩隧道各种施工条件下的开挖过程进行动态的时变力学模拟研究，探讨膨胀围岩-衬砌基于时空效应的相互作用机理及其应力-应变的变化规律，为膨胀岩隧道的结构设计和施工优化提供理论依据。

本项目通过理论学习分析、原状土试验、相似材料试验、室内模型试验以及数值仿真模拟等相互结合的方法，对炎热多雨环境下膨胀围岩隧道施工的时变力学性态、干湿循环下膨胀岩土的软化膨胀机理和不同施工方法膨胀围岩隧道衬砌结构的力学性态进行了研究。具体在运用正交试验设计理论，对适用于隧道模型试验的Ⅳ级弱膨胀围岩相似材料进行了试验研究和隧道模型试验研究干湿循环条件下隧道围岩和衬砌结构的力学变化研究和在不同含水率条件下膨胀围岩隧道在不同施工方法下的力学规律研究。其中“Ⅳ级弱膨胀围岩相似材料的试验研究”、“基于正交设计的Ⅳ级弱膨胀性围岩相似材料试验研究”、“温湿效应对膨胀岩吸水软化作用的影响”“干湿交替条件下膨胀土隧道衬砌内力试验研究”、“干湿交替条件下膨胀围岩隧道的力学性态研究”、“干湿交替条件下膨胀围岩胀缩规律的试验研究”和“基于不同含水率的膨胀围岩隧道施工模拟分析”等成果都对膨胀围岩隧道今后的设计和施工具有较好的参考价值。这些研究成果的应用能给膨胀围岩隧道的建设和运营节省巨大的费用，为今后特殊隧道的建设提供理论依据和技术支撑。