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Spatial Distribution Characteristics of the Full Displacement of Surrounding Rock of a Shallow-Buried Tunnel Section in Soft Rock
(1 Key Laboratory for Special Area Highway Engineering of Ministry of Education, Chang′an University, Xi′an 710064; 2 Railway Engineering Department, Xi′an Railway Vocational & Technical Institute, Wei'nan 714000)
Abstract Information collection for surrounding rock displacement is important for guiding tunnel construction with NATM. Loss of displacement information due to restriction of various factors is inevitable. Based on site-measured data of full displacement in the Alatan tunnel, the release rate of surrounding rock stress at various construction stages is determined, and a 3D numerical analysis of the variation law of the full displacement at the ground surface of a shallow portal section and surrounding rock at the tunnel crown is performed. The results indicate that: 1)the maximum vertical displacement at the surface, measuring 33 mm during tunnel construction, conforms to the measured data, while the vertical displacement at the surface measuring point is far larger than that of the horizontal displacement, and the vertical displacement loss is 42.86% of the total displacement of the surrounding rock; 2) the calculated vertical displacement of the surrounding rock at the tunnel crown is 60 mm, which basically conforms to the site-measured data; 3) the percentages of displacement loss of the surrounding rock at the crown are different in different directions, with 21.42% in the horizontal direction and more than 40% in the vertical direction; and 4) the deformation rate is relatively large—within the scope of 1.0 times the tunnel diameter before and after it passes through the monitoring section—with the vertical displacement being 70% of the total settlement.
Abstract：
Information collection for surrounding rock displacement is important for guiding tunnel construction with NATM. Loss of displacement information due to restriction of various factors is inevitable. Based on site-measured data of full displacement in the Alatan tunnel, the release rate of surrounding rock stress at various construction stages is determined, and a 3D numerical analysis of the variation law of the full displacement at the ground surface of a shallow portal section and surrounding rock at the tunnel crown is performed. The results indicate that: 1)the maximum vertical displacement at the surface, measuring 33 mm during tunnel construction, conforms to the measured data, while the vertical displacement at the surface measuring point is far larger than that of the horizontal displacement, and the vertical displacement loss is 42.86% of the total displacement of the surrounding rock; 2) the calculated vertical displacement of the surrounding rock at the tunnel crown is 60 mm, which basically conforms to the site-measured data; 3) the percentages of displacement loss of the surrounding rock at the crown are different in different directions, with 21.42% in the horizontal direction and more than 40% in the vertical direction; and 4) the deformation rate is relatively large—within the scope of 1.0 times the tunnel diameter before and after it passes through the monitoring section—with the vertical displacement being 70% of the total settlement.
.Spatial Distribution Characteristics of the Full Displacement of Surrounding Rock of a Shallow-Buried Tunnel Section in Soft Rock[J] MODERN TUNNELLING TECHNOLOGY, 2018,V55(1): 114-123
2018, Vol. 55 