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71.
72.
三峡库区巫山移民新城址松散堆积体成因机制研究 总被引:3,自引:0,他引:3
以巫山移民新城址松散堆积体成因类型为例 ,对三峡库区分布较广的松散堆积体进行了研究。通过对大量新开挖剖面的调查测绘 ,在许多地段发现了堆积与基岩之间的滑坡主滑带 ,说明了在该区分布较广的松散堆积体成因具有复合性。它是构造和岩溶作用前提下形成的滑坡体、崩塌体、泥石流堆积体和岩溶坍陷堆积体。运用高分辨率浅层地震勘探揭示堆积体发育深度可达 40 m至 6 0 m ,通过面波测试可按波速将之划分为三层。最后 ,建立了松散堆积体形成演化的概念模型 ,并运用目前最新版本的离散元软件 (UDEC3.0 )对其中最为重要的一种类型滑崩堆积体的形成演化过程进行了模拟。结果表明 ,该区的层状岩体在长江河流下切过程中 ,形成了区域性的卸荷松动 ,而在岩体下部形成压碎张裂带 ;地下水沿卸荷拉裂带渗入 ,并与压裂带贯通 ,形成了岩溶发育带 ,为滑坡、崩塌、塌陷等表生改造提供了条件。 相似文献
73.
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75.
This paper gives the results of an application of the SWEs (shallow water equations) to a part of the Hamburg harbour area, which is a complex flow domain, using the BFG approach, outlined in Part I. The results of a grid doubling procedure generating the desired computational grid from a coarse initial mesh are also presented. A second class of problems which is addressed, demands time-dependent co-ordinate systems. The problems which are solved are the free surface problem for a moving wave which eventually breaks and for a wave which is reflected by the solid walls of a rectangular basin. 相似文献
76.
Nowadays the simulation of free surface flow and transport in rivers, estuaries and seas is often based upon three-dimensional modelling systems. Most of these three-dimensional modelling systems use sigma co-ordinates in the vertical. By the use of the sigma transformation the water column can be divided into the same number of layers independently of the water depth. Especially for steep bottom slopes combined with vertical stratification of the density, sigma-transformed grids impose numerical problems for the accurate approximation of horizontal gradients. This paper deals with algorithms for the approximation in sigma co-ordinates of the horizontal diffusive fluxes of temperature and salinity and for the approximation of the horizontal pressure gradients. The approximation of the horizontal diffusive fluxes is based upon a finite volume method. The approximation of the pressure gradients is directly related to the approximation of the diffusive fluxes. Artificial vertical diffusion and artificial flow due to truncation errors are minimized. The method described in this paper is not hampered by the so-called ‘hydrostatic consistency condition’. This will be illustrated by numerical experiments. 相似文献
77.
G. Cassabois S. Meccherini Ph. Roussignol F. Bogani M. Gurioli M. Colocci R. Planel V. Thierry-Mieg 《Physica E: Low-dimensional Systems and Nanostructures》1998,2(1-4)
The intermediate dimensionality regime is studied on a set of shallow GaAs/Ga
Al
As single quantum wells. Such heterostructures exhibit 2D strong excitonic electroabsorption together with near 3D fast transport properties. We report dephasing time measurements
of the heavy-hole exciton and we show that the acoustic phonon contribution decreases with
to a value in good agreement with theoretical predictions for GaAs bulk. 相似文献
78.
Geir Pedersen 《国际流体数值方法杂志》1986,6(8):497-505
Propagation of periodic waves in the vicinity of irregular saw-tooth shaped boundary in finite difference models is investigated. The reflection of an incoming wave from a single saw-tooth boundary is found to be accompanied by a phase shift. It is shown that any wave mode propagating along such a boundary is trapped and decays in the direction normal to the boundary. A wave propagating along a channel with saw-tooth shaped lateral boundaries is influenced by the trapped waves, which leads to a reduction of the phase velocity. Phase velocities obtained from the present normal mode analysis are compared to velocities in numerical experiments. The agreement is excellent. 相似文献
79.
Babacar Toumbou Daniel Y. Le Roux Abdou Sène 《Journal of Differential Equations》2008,244(8):2020-2040
We present an existence theorem of a two-dimensional sedimentation model coupling a shallow water system with a sediment transport equation. The shallow water system includes Coriolis and friction terms. A Galerkin method is used to obtain a finite-dimensional problem which is solved using a Brouwer fixed point theorem. We prove that the limits of the resulting solution sequences satisfy the model equations. 相似文献
80.
A two-dimensional (in-plane) numerical model for surface waves propagation based on the non-linear dispersive wave approach described by Boussinesq-type equations, which provide an attractive theory for predicting the depth-averaged velocity field resulting from that wave-type propagation in shallow water, is presented. The numerical solution of the corresponding partial differential equations by finite-difference methods has been the subject of several scientific works. In the present work we propose a new approach to the problem: the spatial discretization of the system composed by the Boussinesq equations is made by a finite element method, making use of the weighted residual technique for the solution approach within each element. The model is validated by comparing numerical results with theoretical solutions and with results obtained experimentally. 相似文献