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Study on Mechanical Characteristics and Section Design of Trench Type Opencut Tunnel Lining Structure with Deep Covering Soil under Load Reduction
(1 National and Provincial joint Engineering Laboratory of Road & Bridge Disaster Prevention and Control, Lanzhou Jiaotong University, Lanzhou 730070; 2 Key Laboratory of Transportation Tunnel Engineering of the Ministry of Education, Southwest Jiaotong University, Chengdu 610031; 3 China Railway 14th Bureau Group Co., Ltd, Jinan 250014; 4 College of Civil Engineering, Lanzhou Institute of Technology, Lanzhou 730050)
Abstract In order to improve the internal force of lining structure and reduce the lining thickness of high-filled trench type open-cut tunnel in loess, it studies the variation law of internal forces and lining thickness of structure as well as the effect law of slope angle on internal force of open-cut tunnel and lining thickness before and after load reduction from the perspectives of mechanical behaviors and load reduction mechanism of EPS board by numerical simulation method. The result shows that the internal force and lining thickness of high-filled open-cut structure in loess increase with an increase of filling height; reduction effects of internal force and lining thickness of open-cut tunnel under load reduction are related to EPS board thickness and stress-strain curve, the load reduction effect is the best when EPS board is at the end of plastic stage, and an optimized design for load reduction of EPS board under this density was presented; the greater the slope angle, the smaller the structural internal force of open-cut tunnel before and after load reduction; the lining thickness of open-cut tunnel tends to decrease except the vault; thickness reduction effect of the lining at tunnel roof is most obvious after load reduction while the thickness reduction of other sections decreases in an accelerate way. It is suggested that designs for different EPS board density and thickness should be optimized regarding different filling heights and slope angles of trench type high-filled open-cut tunnels.
Abstract：
In order to improve the internal force of lining structure and reduce the lining thickness of high-filled trench type open-cut tunnel in loess, it studies the variation law of internal forces and lining thickness of structure as well as the effect law of slope angle on internal force of open-cut tunnel and lining thickness before and after load reduction from the perspectives of mechanical behaviors and load reduction mechanism of EPS board by numerical simulation method. The result shows that the internal force and lining thickness of high-filled open-cut structure in loess increase with an increase of filling height; reduction effects of internal force and lining thickness of open-cut tunnel under load reduction are related to EPS board thickness and stress-strain curve, the load reduction effect is the best when EPS board is at the end of plastic stage, and an optimized design for load reduction of EPS board under this density was presented; the greater the slope angle, the smaller the structural internal force of open-cut tunnel before and after load reduction; the lining thickness of open-cut tunnel tends to decrease except the vault; thickness reduction effect of the lining at tunnel roof is most obvious after load reduction while the thickness reduction of other sections decreases in an accelerate way. It is suggested that designs for different EPS board density and thickness should be optimized regarding different filling heights and slope angles of trench type high-filled open-cut tunnels.
ZHUO Bin1 LI Sheng1 HE Chuan2 WANG Huan3 WANG Qicai1 MA Li4
.Study on Mechanical Characteristics and Section Design of Trench Type Opencut Tunnel Lining Structure with Deep Covering Soil under Load Reduction[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(3): 79-87
2019, Vol. 56 