This paper proposes an explicit scheme to analyze the failure of a subsea polyhedral tunnel-liner system with an inverted arch under mechanical loading and fire fields.The thin-walled liner is made of Functionally Gra...This paper proposes an explicit scheme to analyze the failure of a subsea polyhedral tunnel-liner system with an inverted arch under mechanical loading and fire fields.The thin-walled liner is made of Functionally Graded Materials(FGMs),which may improve the stability behavior of the tunnel-liner system.Hydrostatic pressure is inevitable in the liner since underground water may penetrate the cracks of the tunnel,and reach the outer surface of the liner.In addition,an elevated temperature loading is taken into account,considering that fire may occur in the tunnel-liner system.Under the combination of mechanical loading and thermal loading,the liner deforms into a single-lobe shape,which is depicted by a trigonometric function.The total potential energy is expressed quantitatively after the energy approach and thin-walled shell theory are used.The minimum potential energy is obtained when the critical buckling occurs.The critical buckling pressure is calculated,which considers the effect of the thermal field.The present analytical prediction is subsequently compared precisely with other closed-form solutions.Finally,the effects of several parameters,such as the geometric shapes,temperature variations,and volume fraction indices,are discussed to further survey the buckling performance of the nonlinear buckling of an FGM polyhedral liner with an inverted arch.One may address a polyhedral liner with fewer polyhedral sides,and a lower volume fraction index is recommended to rehabilitate cracked tunnels in engineering applications.展开更多
Aiming at the surrounding rock control problem of mining and preparation entries in Xingdong mine with large mining depth, and the comprehensive control countermeasures including high pre-stress cable truss system, th...Aiming at the surrounding rock control problem of mining and preparation entries in Xingdong mine with large mining depth, and the comprehensive control countermeasures including high pre-stress cable truss system, this study put forward powerful anchor support system and anchor cable adaption technology to surrounding rock deformation. Furthermore, the control measures possess the supporting performance with ‘‘primary rigid-following flexible-new rigid, and primary resistance-following yield-new resistance'', which suits deep roadway surrounding rock control. The mechanical model of truss anchor supporting roof beams was established, and the inverted arch deflection produced by the cable pre-stress with stress increment effect and roof beam deflection were obtained. And then the system working mechanism was illustrated. Finally, the surrounding rock support parameters were determined by means of comprehensive methods, and put into practice. The results show that surrounding rock deformation realized secondary stability after three months. The roadway sides convergence value was less than 245mm, and roof subsidence was less than 124mm. In addition, there was no expansion and renovation during service period.展开更多
A detailed experimental research on characteristics of the hydrodynamicpressure spreading in the base gap of the arch inverted plunge pool was carried out. The features ofthe distributon of its ampitudes and spectral ...A detailed experimental research on characteristics of the hydrodynamicpressure spreading in the base gap of the arch inverted plunge pool was carried out. The features ofthe distributon of its ampitudes and spectral density and its characteristics in time domain fortwo conditions, i. e. , (1) a through gap and (2) a blind gap were given. The influence of the dampat the joint opening upon the hydrodynamic pressure inside the gap was also investigated.Accordingly, the stabilization mechanism of the arch invert plunge pool was worked out.展开更多
In this thesis, the scale effect by an aerated water jet diffusing in the water upon the hydrodynamic pressure, the local riverbed scour by multiple layered jets and by those colliding in the vertical and the transver...In this thesis, the scale effect by an aerated water jet diffusing in the water upon the hydrodynamic pressure, the local riverbed scour by multiple layered jets and by those colliding in the vertical and the transverse directions, and the stability of the apron slab both in the inverted arch cushion pool and the flat bottom one by the large discharge and the high water head with 300m level are detailedly researched by means of model test and numerical simulation. A mathematic model simulating the destabilization of the flat bottomed slab is established to open out the mechanism of its stability. Both experimental researches both on the hydrodynamic pressure acted inside joints between the bedrock and the apron slab, and on forces at arch abutments in inverted arch cushion pool are carried out by using an advanced measurement and the imitation means to acquire the mechanism of the inverted arch pool to keep stability and its stability condition.展开更多
基金supported by the Excellent Youth Foundation from the Department of Education,Hunan Province(Grant No.21B0533).
文摘This paper proposes an explicit scheme to analyze the failure of a subsea polyhedral tunnel-liner system with an inverted arch under mechanical loading and fire fields.The thin-walled liner is made of Functionally Graded Materials(FGMs),which may improve the stability behavior of the tunnel-liner system.Hydrostatic pressure is inevitable in the liner since underground water may penetrate the cracks of the tunnel,and reach the outer surface of the liner.In addition,an elevated temperature loading is taken into account,considering that fire may occur in the tunnel-liner system.Under the combination of mechanical loading and thermal loading,the liner deforms into a single-lobe shape,which is depicted by a trigonometric function.The total potential energy is expressed quantitatively after the energy approach and thin-walled shell theory are used.The minimum potential energy is obtained when the critical buckling occurs.The critical buckling pressure is calculated,which considers the effect of the thermal field.The present analytical prediction is subsequently compared precisely with other closed-form solutions.Finally,the effects of several parameters,such as the geometric shapes,temperature variations,and volume fraction indices,are discussed to further survey the buckling performance of the nonlinear buckling of an FGM polyhedral liner with an inverted arch.One may address a polyhedral liner with fewer polyhedral sides,and a lower volume fraction index is recommended to rehabilitate cracked tunnels in engineering applications.
基金provided by the National Natural Science Foundation of China(No.51234005)National Basic Research Program of China under Grant(No.2010CB226802)Fundamental Research Funds for the Central Universities(No.2010QZ06)
文摘Aiming at the surrounding rock control problem of mining and preparation entries in Xingdong mine with large mining depth, and the comprehensive control countermeasures including high pre-stress cable truss system, this study put forward powerful anchor support system and anchor cable adaption technology to surrounding rock deformation. Furthermore, the control measures possess the supporting performance with ‘‘primary rigid-following flexible-new rigid, and primary resistance-following yield-new resistance'', which suits deep roadway surrounding rock control. The mechanical model of truss anchor supporting roof beams was established, and the inverted arch deflection produced by the cable pre-stress with stress increment effect and roof beam deflection were obtained. And then the system working mechanism was illustrated. Finally, the surrounding rock support parameters were determined by means of comprehensive methods, and put into practice. The results show that surrounding rock deformation realized secondary stability after three months. The roadway sides convergence value was less than 245mm, and roof subsidence was less than 124mm. In addition, there was no expansion and renovation during service period.
文摘A detailed experimental research on characteristics of the hydrodynamicpressure spreading in the base gap of the arch inverted plunge pool was carried out. The features ofthe distributon of its ampitudes and spectral density and its characteristics in time domain fortwo conditions, i. e. , (1) a through gap and (2) a blind gap were given. The influence of the dampat the joint opening upon the hydrodynamic pressure inside the gap was also investigated.Accordingly, the stabilization mechanism of the arch invert plunge pool was worked out.
文摘In this thesis, the scale effect by an aerated water jet diffusing in the water upon the hydrodynamic pressure, the local riverbed scour by multiple layered jets and by those colliding in the vertical and the transverse directions, and the stability of the apron slab both in the inverted arch cushion pool and the flat bottom one by the large discharge and the high water head with 300m level are detailedly researched by means of model test and numerical simulation. A mathematic model simulating the destabilization of the flat bottomed slab is established to open out the mechanism of its stability. Both experimental researches both on the hydrodynamic pressure acted inside joints between the bedrock and the apron slab, and on forces at arch abutments in inverted arch cushion pool are carried out by using an advanced measurement and the imitation means to acquire the mechanism of the inverted arch pool to keep stability and its stability condition.
