Underground facilities are usually constructed under existing buildings,or buildings are constructed over existing underground structures.It is then imperative to account for the current overburden loads and future su...Underground facilities are usually constructed under existing buildings,or buildings are constructed over existing underground structures.It is then imperative to account for the current overburden loads and future surface loadings in the design of tunnels.In addition,tunnels are often constructed beneath the groundwater level,such as cross-river tunnels.Therefore,it is also important to consider the water pressure impact on the tunnel lining behaviour.Tunnels excavated by a conventional tunnelling method are considered in this paper.The hyperstatic reaction method(HRM)is adopted in this study to investigate the effect of surcharge loading on a horseshoe-shaped tunnel behaviour excavated in saturated soft rocks.The results obtained from the HRM and numerical modelling are in good agreement.Parametric studies were then performed to show the effects of the water pressure,surcharge loading value and its width,and groundwater level on the behaviour of the horseshoe-shaped tunnel lining,in terms of internal forces and displacements.It displays that the bending moment,normal forces and radial displacements are more sensitive to the water pressure,surcharge loading and groundwater level.展开更多
Subsea tunnel lining structures should be designed to sustain the loads transmitted from surrounding ground and groundwater during excavation. Extremely high pore-water pressure reduces the effective strength of the c...Subsea tunnel lining structures should be designed to sustain the loads transmitted from surrounding ground and groundwater during excavation. Extremely high pore-water pressure reduces the effective strength of the country rock that surrounds a tunnel, thereby lowering the arching effect and stratum stability of the structure. In this paper, the mechanical behavior and shape optimization of the lining structure for the Xiang＇an tunnel excavated in weathered slots are examined. Eight cross sections with different geometric parameters are adopted to study the mechanical behavior and shape optimization of the lining structure. The hyperstatic reaction method is used through finite element analysis software ANSYS. The mechanical behavior of the lining structure is evidently affected by the geometric parameters of crosssectional shape. The minimum safety factor of the lining structure elements is set to be the objective function. The efficient tunnel shape to maximize the minimum safety factor is identified. The minimum safety factor increases significantly after optimization. The optimized cross section significantly improves the mechanical characteristics of the lining structure and effectively reduces its deformation. Force analyses of optimization process and program are conducted parametrically so that the method can be applied to the optimization design of other similar structures. The results obtained from this study enhance our understanding of the mechanical behavior of the lining structure for subsea tunnels. These results are also beneficial to the optimal design of lining structures in general.展开更多
Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some im...Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some improvements to the use of the Hyperstatic Reaction Method-HRM for analysing tunnels with horseshoe-shaped cross-sections when these tunnels operate under the influence of earthquakes, particularly in cases when the tunnel lining is a continuous lining. The analysis used parameters of a tunnel from the Hanoi metro system, as well as parameters of the strongest earthquake that may occur in the central Hanoi area in the improved HRM and 2 D numerical methods using the ABAQUS software. On the basis of the results obtained, the paper gives conclusions about the HRM methodology when it is used to calculate tunnels that have horseshoe cross-sections operating under the influence of earthquakes.展开更多
基金The first author is supported by the Fundamental Research Funds for the Central Universities in China.The third author is supported by the Vietnam Ministry of Education and Training under grant number B2020-MDA-15.These funds are greatly appreciated.
文摘Underground facilities are usually constructed under existing buildings,or buildings are constructed over existing underground structures.It is then imperative to account for the current overburden loads and future surface loadings in the design of tunnels.In addition,tunnels are often constructed beneath the groundwater level,such as cross-river tunnels.Therefore,it is also important to consider the water pressure impact on the tunnel lining behaviour.Tunnels excavated by a conventional tunnelling method are considered in this paper.The hyperstatic reaction method(HRM)is adopted in this study to investigate the effect of surcharge loading on a horseshoe-shaped tunnel behaviour excavated in saturated soft rocks.The results obtained from the HRM and numerical modelling are in good agreement.Parametric studies were then performed to show the effects of the water pressure,surcharge loading value and its width,and groundwater level on the behaviour of the horseshoe-shaped tunnel lining,in terms of internal forces and displacements.It displays that the bending moment,normal forces and radial displacements are more sensitive to the water pressure,surcharge loading and groundwater level.
基金financially supported by the National Natural Science Foundation of China(Grant No.51308012)the Key Laboratory of Transportation Tunnel Engineering+1 种基金Ministry of EducationSouthwest Jiaotong University(Grant No.TTE2014-06)
文摘Subsea tunnel lining structures should be designed to sustain the loads transmitted from surrounding ground and groundwater during excavation. Extremely high pore-water pressure reduces the effective strength of the country rock that surrounds a tunnel, thereby lowering the arching effect and stratum stability of the structure. In this paper, the mechanical behavior and shape optimization of the lining structure for the Xiang＇an tunnel excavated in weathered slots are examined. Eight cross sections with different geometric parameters are adopted to study the mechanical behavior and shape optimization of the lining structure. The hyperstatic reaction method is used through finite element analysis software ANSYS. The mechanical behavior of the lining structure is evidently affected by the geometric parameters of crosssectional shape. The minimum safety factor of the lining structure elements is set to be the objective function. The efficient tunnel shape to maximize the minimum safety factor is identified. The minimum safety factor increases significantly after optimization. The optimized cross section significantly improves the mechanical characteristics of the lining structure and effectively reduces its deformation. Force analyses of optimization process and program are conducted parametrically so that the method can be applied to the optimization design of other similar structures. The results obtained from this study enhance our understanding of the mechanical behavior of the lining structure for subsea tunnels. These results are also beneficial to the optimal design of lining structures in general.
基金supported by the Saint Petersburg Mining University
文摘Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some improvements to the use of the Hyperstatic Reaction Method-HRM for analysing tunnels with horseshoe-shaped cross-sections when these tunnels operate under the influence of earthquakes, particularly in cases when the tunnel lining is a continuous lining. The analysis used parameters of a tunnel from the Hanoi metro system, as well as parameters of the strongest earthquake that may occur in the central Hanoi area in the improved HRM and 2 D numerical methods using the ABAQUS software. On the basis of the results obtained, the paper gives conclusions about the HRM methodology when it is used to calculate tunnels that have horseshoe cross-sections operating under the influence of earthquakes.
