Effects of the ring-cut excavation method on the restraint of displacements ahead of a tunnel face

Hisatake, Masayasu; Ohno, S.; Katayama, Tatsuaki; Ohmae, Yukihiro; Sano, Shinsuku

doi:10.1016/j.tust.2009.02.003

Cited by 9 publications

(1 citation statement)

References 5 publications

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“…In loosen sand layer, the fine grain content rate and water content ratio are effective index [4]. The pressure dependencies and modulus of deformation are also considered to evaluate tunnel face stability in the ring-cut excavation method [5].…”

Section: Introductionmentioning

confidence: 99%

Experimental study of frictional resistance influences on tunnel face stability

Kawanoue

Yagihashi

Togashi

et al. 2023

IOP Conf. Ser.: Earth Environ. Sci.

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In recent years, there have been several ground surface collapses due to tunnel excavation in Japan. Although such accident is caused by ground loosening and tunnel face collapses due to excavation, there is no accepted theory for estimating the face stability because this phenomenon is quite complicated and highly influenced by the supports and lining types. Specifically, the loosened area is relatively large for the urban NATM method, which applied in a shallow sedimentary rock layer. Therefore, a method to quantitatively evaluate the tunnel face stability by this kind of mechanical property is essential. In this study, 2D tunnel pull-out test was conducted to observe the influence of frictional resistance on tunnel face failure and loosening area by changing the shear resistance angle using three particle sizes of dry silica sand and different variation of earth covering. The result demonstrated that failure region doesn’t reach the ground surface when the shear resistance angle is 46.4° and covering thickness to tunnel height ratio H/D is over 5 or the angle is 55.8° and H/D is over 3. This study considered that there is an arch effect depending on frictional resistance and earth coverings occurred. Furthermore, even with the same earth covering, the smaller the shear resistance is, the earlier the ground surface collapses. Therefore, it could be said that the higher the frictional resistance is, the later the collapse proceeds.

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Section: Introductionmentioning

confidence: 99%