Classification of Soil Ground depending on the Evaluation of Tunnel Face Stability.

DOI Web Site 15 References

Bibliographic Information

Other Title
  • 土砂トンネルの切羽安定性評価に基づく地山分類法
  • ドシャ トンネル ノ キリハ アンテイセイ ヒョウカ ニ モトヅク ジヤマ ブンルイホウ

Search this article

Abstract

Soil ground is a general term for cohesive soil, sandy soil, gravelly soil and other special types of soils such as pyroclastic deposit, which are commonly featured by low strength. One of the most important problems for tunnel construction is the face wash-out due to water gush at the soil ground, which is composed of granular soils other than cohesive soil. Therefore, the face stability is a condition required for tunnel support design for granular soil ground. The author performed a statistical analysis of some tunnel construction data on sandy ground, model experimental study and numerical parametric analysis on the critical condition, in order to make clear distinction among changes in face state.<BR>In this paper, the author suggests a following classification standard of sandy ground conditions for railway tunnels from the results of the above research.<BR>[IN]: ground state of considerably stable face<BR>[IL]: ground state of unstable face to cause wash-out due to small changes in face stability balance for the worse<BR>[SL]: ground state of extremely unstable face, worth than [IL] for which serious troubles are foreseeable in excavation<BR>The boundary between for the ground classes [IN] and [IL] is distinguished by the fine grain content (Fc) of soils; ground condition of class [IN] having Fe≥10%. The boundary of [IL] and [SL] is also distinguished by the relative density (Dr) of soils; class [SL] having Dr<80%. Above classification can be applied to the conditions where the pressure head (WL) from the tunnel face center is WL<10m.<BR>Further, the author suggests a method to classify different types of soil ground, that is obtained from experimental studies of evaluation of granular soil except sandy soil and a consideration of characteristic conditions of layered ground structures with complicated geological conditions.

Journal

References(15)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top