With the utilization of underground space,backward erosion piping(BEP)has been observed in many underground structures(e.g.,shield tunnels)founded on sandy aquifers.However,due to invisibility,the geometry of the erod...With the utilization of underground space,backward erosion piping(BEP)has been observed in many underground structures(e.g.,shield tunnels)founded on sandy aquifers.However,due to invisibility,the geometry of the eroded pipe and its spatial evolution with time during the piping process was still not clear.In this study,we developed a Hele-Shaw cell to visualize the dynamic progression of BEP.With imaging process technology,we obtained a typical process of BEP(the erosion process can be divided into a piping progression phase and a piping stabilization phase),quantitatively characterized the formation of erosion pipes,and compared the patterns of erosion(e.g.,the erosion area A and the maximum erosion radius R)that spontaneously develop under different fluxes of water.The most interesting finding is that the sand grains in a thicker Hele-Shaw model are easier to dislodge,which is possibly due to the granular system in a thicker model having more degrees of freedom,reducing the stability of the sand grains.展开更多
We theoretically study the temperature dependence of the excitonic spectra of monolayer transitionmetal dichaleogenides using the O＇Donnell equation, Eg（T） = Eg（0） - S〈hω〉[coth（〈hω〉/2kBT- 1）]. We develop ...We theoretically study the temperature dependence of the excitonic spectra of monolayer transitionmetal dichaleogenides using the O＇Donnell equation, Eg（T） = Eg（0） - S〈hω〉[coth（〈hω〉/2kBT- 1）]. We develop a theoretical model for the quantitative estimation of the Huang-Rhys factor S and averagephonon energy （hω） based on exciton coupling with longitudinal optical and acoustic phonons in the Frohlich and deformation potential mechanisms, respectively. We present reasonable explanations for the fitted values of the Huang-Rhys factor and average phonon energy adopted in experiments. Com- parison with experimental results reveals that the temperature dependence of the peak position in the excitonic spectra can be well reproduced by modulating the polarization parameter and deformation potential constant.展开更多
基金the National Engineering Laboratory for Digital Construction and Evaluation Technology of Urban Rail Transit(No.2021GY01)the National Natural Science Foundation of China(No.41630641)。
文摘With the utilization of underground space,backward erosion piping(BEP)has been observed in many underground structures(e.g.,shield tunnels)founded on sandy aquifers.However,due to invisibility,the geometry of the eroded pipe and its spatial evolution with time during the piping process was still not clear.In this study,we developed a Hele-Shaw cell to visualize the dynamic progression of BEP.With imaging process technology,we obtained a typical process of BEP(the erosion process can be divided into a piping progression phase and a piping stabilization phase),quantitatively characterized the formation of erosion pipes,and compared the patterns of erosion(e.g.,the erosion area A and the maximum erosion radius R)that spontaneously develop under different fluxes of water.The most interesting finding is that the sand grains in a thicker Hele-Shaw model are easier to dislodge,which is possibly due to the granular system in a thicker model having more degrees of freedom,reducing the stability of the sand grains.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 11674241） and Young Core Instructor of Peiyang （Crant No. 11303267）.
文摘We theoretically study the temperature dependence of the excitonic spectra of monolayer transitionmetal dichaleogenides using the O＇Donnell equation, Eg（T） = Eg（0） - S〈hω〉[coth（〈hω〉/2kBT- 1）]. We develop a theoretical model for the quantitative estimation of the Huang-Rhys factor S and averagephonon energy （hω） based on exciton coupling with longitudinal optical and acoustic phonons in the Frohlich and deformation potential mechanisms, respectively. We present reasonable explanations for the fitted values of the Huang-Rhys factor and average phonon energy adopted in experiments. Com- parison with experimental results reveals that the temperature dependence of the peak position in the excitonic spectra can be well reproduced by modulating the polarization parameter and deformation potential constant.
