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Calculation Method for Loosening Earth Pressure of a Shallow-Buried Tunnel Considering the Soil Arch Effect
(1 School of Civil and Architectural Engineering, Anhui University of Science and Technology, Huainan 232001; 2 Center for PostDoctoral Studies of Civil Engineering, Anhui University of Science and Technology, Huainan 232001)
Abstract With an increase of crown displacement of a shallow-buried tunnel, the soil arch structure experiences four stages: the upper concave arch, the triangular arch, the lower concave arch and the rectangular arch. For shal?low-buried tunnel construction, the soil arch structure is mainly composed of a lower concave and rectangular arch,and the soil arch effect varies constantly with the variation of the arch structure. Criteria for judging the arch structure is established assuming the tunnel arch structure is a lower concave arch. The theoretical side displacement δ1′is obtained based on crown displacement δ. When the displacements δ1 at the two sides during tunnel construction are larger than the theoretical side displacement δ1′ of the lower concave arch, the arch structure develops as a rectangular arch, otherwise it develops as a lower concave arch. Based on an analysis of the laminar differential chromatographic method, a calculation formula for the loosening soil pressure of shallow-buried tunnels is presented. Ex? ample calculations show the loosening earth pressure of a shallow-buried tunnel has a direct relationship with the soil arch structure, and the loosening earth pressure will decrease substantially when the soil mass develops as a rectangular arch from a lower concave arch, which means the influence of the soil arch effect increases.
Abstract：
With an increase of crown displacement of a shallow-buried tunnel, the soil arch structure experiences four stages: the upper concave arch, the triangular arch, the lower concave arch and the rectangular arch. For shal?low-buried tunnel construction, the soil arch structure is mainly composed of a lower concave and rectangular arch,and the soil arch effect varies constantly with the variation of the arch structure. Criteria for judging the arch structure is established assuming the tunnel arch structure is a lower concave arch. The theoretical side displacement δ1′is obtained based on crown displacement δ. When the displacements δ1 at the two sides during tunnel construction are larger than the theoretical side displacement δ1′ of the lower concave arch, the arch structure develops as a rectangular arch, otherwise it develops as a lower concave arch. Based on an analysis of the laminar differential chromatographic method, a calculation formula for the loosening soil pressure of shallow-buried tunnels is presented. Ex? ample calculations show the loosening earth pressure of a shallow-buried tunnel has a direct relationship with the soil arch structure, and the loosening earth pressure will decrease substantially when the soil mass develops as a rectangular arch from a lower concave arch, which means the influence of the soil arch effect increases.
.Calculation Method for Loosening Earth Pressure of a Shallow-Buried Tunnel Considering the Soil Arch Effect[J] MODERN TUNNELLING TECHNOLOGY, 2017,V54(4): 56-62
2017, Vol. 54 