Dynamic failure of rock masses around deep tunnels,such as fault-slip rockburst and seismic-induced collapse,can pose a significant threat to tunnel construction safety.One of the most significant factors that control...Dynamic failure of rock masses around deep tunnels,such as fault-slip rockburst and seismic-induced collapse,can pose a significant threat to tunnel construction safety.One of the most significant factors that control the accuracy of its risk assessment is the estimation of the ground motion around a tunnel caused by seismicity events.In general,the characteristic parameters of ground motion are estimated in terms of empirical scaling laws.However,these scaling laws make it difficult to accurately estimate the near-field ground motion parameters because the roles of control factors,such as tunnel geometry,damage zone distribution,and seismic source parameters,are not considered.For this,the finite fracturing seismic source model(FFSSM)proposed in this study is used to simulate the near-field ground motion characteristics around deep tunnels.Then,the amplification effects of ground motion caused by the interaction between seismic waves and deep tunnels and corresponding control factors are studied.The control effects of four factors on the near-field ground motion amplification effect are analyzed,including the main seismic source wavelength,tunnel span,tunnel shape,and range of damage zones.An empirical formula for the maximum amplification factor(a_(m))of the near-field ground motion around deep tunnels is proposed,which consists of four control factors,i.e.the wavelength control factor(F_(λ)),tunnel span factor(F_(D)),tunnel shape factor(F_(s))and excavation damage factor(F_(d)).This empirical formula provides an easy approach for accurately estimating the ground motion parameters in seismicityprone regimes and the rock support design of deep tunnels under dynamic loads.展开更多
In this paper, a panel method based on three dimensional potential flow theory is used to study the problem of wave added resistance. The time-domain motion response of Wigely III ship in head waves is calculated by A...In this paper, a panel method based on three dimensional potential flow theory is used to study the problem of wave added resistance. The time-domain motion response of Wigely III ship in head waves is calculated by AQWA, and then the wave added resistance of ship is obtained by near-field pressure integration method. By comparing the calculated results with the experimental data in literature, it is shown that the variation trend and peak value are in good agreement, and the accuracy and efficiency meet the research requirements. Based on the above mentioned method, the wave added resistance of a deep-V hybrid monohull in head waves is studied. The motions and wave added resistances of the deep-V hybrid monohull and the deep-V original ship advancing in head waves with various forward speed and wave frequencies are calculated and analyzed. The results show that the longitudinal motion response of the deep-V hybrid monohull is effectively suppressed and the wave added resistance is obviously reduced, the new type of ship has good engineering application prospects. The present method provides an approach of satisfactory accuracy and efficiency to predict wave added resistance of ships voyaging in waves.展开更多
In this paper,we consider the inverse acoustic scattering problem by an unbounded rough surface.A direct imaging method is proposed to reconstruct the rough surfaces from scattered-field data for incident plane waves ...In this paper,we consider the inverse acoustic scattering problem by an unbounded rough surface.A direct imaging method is proposed to reconstruct the rough surfaces from scattered-field data for incident plane waves and the performance analysis is also presented.The reconstruction method is very robust to noises of measured data and does’t need to know the type of the boundary conditions of the surfaces in advance.Finally,numerical examples are carried out to illustrate that our method is fast,accurate and stable even for the case of multiple-scale profiles.展开更多
基金jointly supported by the National Natural Science Foundation of China(Grant No.41877256)the Natural Science Foundation of Hubei Province(Grant No.ZRQT2020000114)the Key Research Program of the Chinese Academy of Sciences(Grant No.KFZD-SW-423)。
文摘Dynamic failure of rock masses around deep tunnels,such as fault-slip rockburst and seismic-induced collapse,can pose a significant threat to tunnel construction safety.One of the most significant factors that control the accuracy of its risk assessment is the estimation of the ground motion around a tunnel caused by seismicity events.In general,the characteristic parameters of ground motion are estimated in terms of empirical scaling laws.However,these scaling laws make it difficult to accurately estimate the near-field ground motion parameters because the roles of control factors,such as tunnel geometry,damage zone distribution,and seismic source parameters,are not considered.For this,the finite fracturing seismic source model(FFSSM)proposed in this study is used to simulate the near-field ground motion characteristics around deep tunnels.Then,the amplification effects of ground motion caused by the interaction between seismic waves and deep tunnels and corresponding control factors are studied.The control effects of four factors on the near-field ground motion amplification effect are analyzed,including the main seismic source wavelength,tunnel span,tunnel shape,and range of damage zones.An empirical formula for the maximum amplification factor(a_(m))of the near-field ground motion around deep tunnels is proposed,which consists of four control factors,i.e.the wavelength control factor(F_(λ)),tunnel span factor(F_(D)),tunnel shape factor(F_(s))and excavation damage factor(F_(d)).This empirical formula provides an easy approach for accurately estimating the ground motion parameters in seismicityprone regimes and the rock support design of deep tunnels under dynamic loads.
基金financial support from the National Natural Science Foundation of China (Nos.51709246, U1806229, 51809244, and 51609220)the Fundamental Research Funds for the Central Universities (No.201713031)。
文摘In this paper, a panel method based on three dimensional potential flow theory is used to study the problem of wave added resistance. The time-domain motion response of Wigely III ship in head waves is calculated by AQWA, and then the wave added resistance of ship is obtained by near-field pressure integration method. By comparing the calculated results with the experimental data in literature, it is shown that the variation trend and peak value are in good agreement, and the accuracy and efficiency meet the research requirements. Based on the above mentioned method, the wave added resistance of a deep-V hybrid monohull in head waves is studied. The motions and wave added resistances of the deep-V hybrid monohull and the deep-V original ship advancing in head waves with various forward speed and wave frequencies are calculated and analyzed. The results show that the longitudinal motion response of the deep-V hybrid monohull is effectively suppressed and the wave added resistance is obviously reduced, the new type of ship has good engineering application prospects. The present method provides an approach of satisfactory accuracy and efficiency to predict wave added resistance of ships voyaging in waves.
基金supported by the National Natural Science Foundation of China(Nos.11871466,11571355)。
文摘In this paper,we consider the inverse acoustic scattering problem by an unbounded rough surface.A direct imaging method is proposed to reconstruct the rough surfaces from scattered-field data for incident plane waves and the performance analysis is also presented.The reconstruction method is very robust to noises of measured data and does’t need to know the type of the boundary conditions of the surfaces in advance.Finally,numerical examples are carried out to illustrate that our method is fast,accurate and stable even for the case of multiple-scale profiles.
