Development of new tunneling method using X-ray CT

点击翻译按钮获取中文摘要

In recent years, mountain tunneling method such as NATM (New Austrian Tunneling Method) has been used for tunnel construction even in the urban area. In Japan where land area is small, it is required that tunnel is constructed into unconsolidated ground or low overburden ground. When excavating a tunnel, tunnel face becomes very unstable due to stress release caused by excavation. It is a main issue to maintain the stability in tunnel face during construction. To create the condition for safe construction, it is necessary that tunnel face is reinforced by auxiliary method. However, failure zone due to tunneling is a behavior in three dimensions and the mechanism of face failure in three dimensions has not been well known yet.The objective of this research is to investigate tunnel face failure in three dimensions and to evaluate the mechanism of the auxiliary method. And finally, the new tunneling method with the auxiliary method is proposed. Here in this study, an Industrial X-ray CT was used in order to investigate the behavior in the soils. And the results of model test were checked with centrifuge modeling test for the purpose of in-situ stress level. Followings are the list of conclusions :1. A new testing system combining model test with X-ray CT was developed ;2. Effect image analysis method for getting proper X-ray image was developed ;3. The mechanism of tunnel face failure was well investigated using the test system developed in this research ;4. A series of centrifuge model tests were conducted for the purpose of checking the behavior of in-situ stress level ;5. One tunneling method was proposed based on the results of this research ;6. The effect of the auxiliary method was well investigated using a new test apparatus, direct shear test with CT scanning ;7. The effect cf the auxiliary method was also investigated with 1G model test and centrifuge test ;8. and finally, all the results obtained here in this research were summarized.