共查询到20条相似文献，搜索用时 15 毫秒
1.
Hydraulic crack propagation in a porous medium 总被引：2，自引：0，他引：2
We develop a model for the propagation of a fluid-filled crack in a porous medium. The problem is motivated by the mechanism whereby drainage networks may form in partially molten rock below the Earth's lithosphere. Other applications include the propagation of hydraulic fractures in jointed rocks and in oil drilling operations, and the formation of dessication cracks in soils. Motivated by the lithospheric problem, we study a situation in which gravity acts in the direction of crack propagation. The model couples the elastoliydrodynamic equations of crack propagation with a pore pressure field in the porous rock, which drives the fluid flow which supplies the crack. The effect of the pore flow is to include a diffusional term in the evolution equation for the crack width, thus allowing a crack initiated at the base of the lithosphere to propagate down into the asthenosphere. Asymptotic and numerical solutions are presented for this crack evolution. However, the predicted drainage of melt into this crack is tiny compared with the upward percolative melt migration, and the predicted width of cracks (millimetres) is much too small to allow propagation of melt into the lithosphere without freezing. As a mechanism to explain magma fracturing in the lithosphere, the process described here therefore requires further refinement. 相似文献
2.
3.
4.
A mathematical model of vulcanian eruptions 总被引：2，自引：0，他引：2
D. L. Turcotte H. Ockendon J. R. Ockendon S. J. Cowley 《Geophysical Journal International》1990,103(1):211-217
5.
6.
7.
8.
Magnetic anisotropy produced by magma flow: theoretical model and experimental data from Ferrar dolerite sills (Antarctica) 总被引：3，自引：0，他引：3
Volcanic rocks forming sills, dykes or lava flows may display a magnetic anisotropy derived from the viscous flow during their emplacement. We model a sill as a steady-state flow of a Bingham fluid, driven by a pressure gradient in a horizontal conduit. The magma velocity as a function of depth is calculated from the motion and constitutive equations. Vorticity and strain rate are determined for a reference system moving with the fluid. The angular velocity and the orientation of an ellipsoidal magnetic grain immersed in the fluid are calculated as functions of time or strain. Magnetic susceptibility is then calculated for a large number of grains with a uniform distribution of initial orientations. It is shown that the magnetic lineation oscillates in the vertical plane through the magma flow direction, and that the magnetic foliation plane changes periodically from horizontal to vertical. The results are compared with the magnetic fabric of Ferrar dolerite sills (Victoria Land, East Antarctica) derived from low-field susceptibility measurements. 相似文献
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.