Generalised Theory of Exit Gradients for the Stability of Sloping Surfaces in Porous Media against Efflux of Seepage

Mention is made of the theory of exit gradients as applied to the design of weirs on permeable foundations, which conceives of granular material for the porous media and a horizontal surface of exit in rear. Situations are cited where efflux of seepage occurs from sloping surfaces as on the rear face of levees, and also through soils having friction and cohesion. A generalised equation for exit gradients talcing the effect of slope, friction and cohesion, has been deduced. The validity of analytical equation was tested by experimental studies. But the present paper furnishes only results and conclusions of those studies, and no details of the experimental investigations. A practical example has been worked out and included in Appendix I to illustrate the use of the equations derived. It is hoped that the investigation referred to, extends our knowledge of the theory of flotation gradients which has utility in the design of hydraulic structures on permeable foundation.