• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.5
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• pp.459-470
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• 2014

Now-a-days, the trend in constructing tunnels is to build more deeper, more longer tunnels of greater cross-sections. That's why, the demand of "Early-high-strength shotcrete" is very high because of their advantage of attaining higher strength immediately after excavation, which controls the ground subsidence. So, this study reveals the supporting phenomena of early-high-strength shotcrete, using three-dimensional numerical analysis. The crux of this study can be applied practically in construction sites also. Support Performance of two different qualities of shotcrete was checked out, by keeping the general shotcrete's thickness constant and comparing it with early-high-strength shotcrete's thickness decreasing it gradually in five steps, and analysing/comparing the support performance in all cases. Effect of using early-high-strength shotcrete was analysed to save the cost of steel sets, which are widely used for supporting the ground before the hardening of general shotcrete. The results of numerical analysis on the performance of early-high-strength shotcrete show that, it behaves more effectively under worse ground conditions and it can support the ground more conveniently than steel sets, before the shotcrete is hardened.

• Journal of the Korean GEO-environmental Society
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• v.9 no.5
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• pp.29-36
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• 2008

The shotcrete is a NATM technique as a major tunnel support for ground stability after tunnel excavation. Instead of a general concrete lining method, it is a trend for curtail of construction periods and reduction of construction expenses that required to use of the permanent shotcrete lining. This high-strength shotcrete is required to use as a permanent shotcrete lining. This brought out the solution of environmental pollution and harmfulness to human. Accordingly, in this study specimens for strength measurement were made to develop shotcrete possible to develop materials in early with cement mineral accelerator as NATM method construction. It was compared with existing shotcrete material, unconfined compression test, flexural strength test, antiwashout underwater test were experimented. The fish poison test was experimented to evaluate an influence of environment. As a results of the test, unconfined compressive strength and flexural strength were equivalent with 28-curing day strength of existing material. An antiwashout of research subject material was revealed excellently in antiwashout Underwater test. As a results of the fish poison, an evaluation research subject material was founded more environmentally friendly than existing shotcrete.