Balance of the groundwater and ecology is crucial for controlled discharge.However,regarding the segments of tunnel boring machines(TBMs)under high water pressure,the stability of the lining structure is often reduced...Balance of the groundwater and ecology is crucial for controlled discharge.However,regarding the segments of tunnel boring machines(TBMs)under high water pressure,the stability of the lining structure is often reduced by excessive drain holes required to achieve this balance.The large discharge of pinholes can easily have severe consequences,such as the lowering of the groundwater table,drying of springs,and vegetation wilting.Thus,in this study,according to the fluid-structure coupling theory,a new drainage design for TBM segments was developed by considering a mountain tunnel subject to a high water pressure as a case study.The evolution characteristics,including the external water pressure of the lining,discharge volume of the segment,and groundwater-table drawdown,were investigated via numerical modeling with drain holes and pinholes.The results indicated that the optimal design parameters of drainage segments for the project case were as follows:a circumferential spacing angle and longitudinal number on one side of a single ring of 51°and 2,respectively,for the drain holes and an inclination angle and length of 46.41°and 0.25 times the grouting thickness,respectively,for the pin holes.展开更多
In this paper, based upon the basic solution of sink, the approximate solution of single drain hole in finite elements is derived by use of the superposition principle. Then, the theoretical solution is extended to th...In this paper, based upon the basic solution of sink, the approximate solution of single drain hole in finite elements is derived by use of the superposition principle. Then, the theoretical solution is extended to the case of some drain holes in one finite element, and the method is used in seepage control analysis with quick convergence and high accuracy. On the other hand, if the positions of the drain holes are changed, only some control factors of drain holes are changed, but the finite element grid need not to be reformed. Therefore, the method is more suitable in optimal research of seepage control.展开更多
The behaviours of three types of hot-hole injections in ultrashort channel lightly doped drain （LDD） nMOSFETs with ultrathin oxide under an alternating stress have been compared. The three types of hot-hole injectio...The behaviours of three types of hot-hole injections in ultrashort channel lightly doped drain （LDD） nMOSFETs with ultrathin oxide under an alternating stress have been compared. The three types of hot-hole injections, i.e. low gate voltage hot hole injection （LGVHHI）, gate-induced drain leakage induced hot-hole injection （GIDLIHHI） and substrate hot-hole injection （SHHI）, have different influences on the devices damaged already by the previous hot electron injection （HEI） because of the different locations of trapping holes and interface states induced by the three types of injections, i.e. three types of stresses. Experimental results show that GIDLIHHI and LGVHHI cannot recover the degradation of electron trapping, but SHHI can. Although SHHI can recover the device＇s performance, the recovery is slight and reaches saturation quickly, which is suggested here to be attributed to the fact that trapped holes are too few and the equilibrium is reached between the trapping and releasing of holes which can be set up quickly in the ultrathin oxide.展开更多
基金the National Natural Science Foundation of China(Grant No.41972276)the Natural Science Foundation of Fujian Province(No.2020J06013)the"Foal Eagle Program"Youth Top-notch Talent Project of Fujian Province(No.00387088),The financial support is gratefully acknowledged.
文摘Balance of the groundwater and ecology is crucial for controlled discharge.However,regarding the segments of tunnel boring machines(TBMs)under high water pressure,the stability of the lining structure is often reduced by excessive drain holes required to achieve this balance.The large discharge of pinholes can easily have severe consequences,such as the lowering of the groundwater table,drying of springs,and vegetation wilting.Thus,in this study,according to the fluid-structure coupling theory,a new drainage design for TBM segments was developed by considering a mountain tunnel subject to a high water pressure as a case study.The evolution characteristics,including the external water pressure of the lining,discharge volume of the segment,and groundwater-table drawdown,were investigated via numerical modeling with drain holes and pinholes.The results indicated that the optimal design parameters of drainage segments for the project case were as follows:a circumferential spacing angle and longitudinal number on one side of a single ring of 51°and 2,respectively,for the drain holes and an inclination angle and length of 46.41°and 0.25 times the grouting thickness,respectively,for the pin holes.
文摘In this paper, based upon the basic solution of sink, the approximate solution of single drain hole in finite elements is derived by use of the superposition principle. Then, the theoretical solution is extended to the case of some drain holes in one finite element, and the method is used in seepage control analysis with quick convergence and high accuracy. On the other hand, if the positions of the drain holes are changed, only some control factors of drain holes are changed, but the finite element grid need not to be reformed. Therefore, the method is more suitable in optimal research of seepage control.
文摘The behaviours of three types of hot-hole injections in ultrashort channel lightly doped drain （LDD） nMOSFETs with ultrathin oxide under an alternating stress have been compared. The three types of hot-hole injections, i.e. low gate voltage hot hole injection （LGVHHI）, gate-induced drain leakage induced hot-hole injection （GIDLIHHI） and substrate hot-hole injection （SHHI）, have different influences on the devices damaged already by the previous hot electron injection （HEI） because of the different locations of trapping holes and interface states induced by the three types of injections, i.e. three types of stresses. Experimental results show that GIDLIHHI and LGVHHI cannot recover the degradation of electron trapping, but SHHI can. Although SHHI can recover the device＇s performance, the recovery is slight and reaches saturation quickly, which is suggested here to be attributed to the fact that trapped holes are too few and the equilibrium is reached between the trapping and releasing of holes which can be set up quickly in the ultrathin oxide.
