In order to draw a flow net for such a dam, the horizontal scale of the dam is first reduced by multiplying a scaling factor (kh/kv) 0.5 and a flow net is constructed assuming that the medium is isotropic.

If an impermeable cutoff is installed to 60 % of the depth of the permeable foundation, the flow net and downstream slope gradient is only slightly modified to a lower level. In Fig.6.3(b), a transformed section and a flow net thus drawn for the case kh=9kv is presented. use of flow-net in earth dam and levee design.

a brief review is presented of many possible applications of the flow-net to earth dam and levee design suggesting some techniques of constructing flow-nets, particularly those having an indeterminate phreatic line. flow of water through soil masses is but one of the number of forms of stream-line flow that can be studied with the flow-net. The true flow net If an impermeable cutoff is installed to 60 % of the depth of the permeable foundation, the flow net and downstream slope gradient is only slightly modified to a lower level. Figure 1 shows an example of flow net construction. In order to achieve these objectives, an experimental flow net system inside the body of a homogeneous earth embankment dam model was formulated by using a drainage and seepage tank. 2.1 FLOW NET.

Flow Nets 1 10.1 Introduction Let us consider a state of plane seepage as for example in the earth dam shown in Figure 1. 2) Numerical solution based on parabola Numerical Solution Dupuit Solution Modified Laplace equation Assumes: a) Flow lines to be nearly horizontal b) Hydraulic gradient of the flow is equal to the slope of the phreatic surface x y i � From the constructed flow net in the present experimental research paper, an attempt has been made to analyze, determine and present the following parameters: - 2113 - An earth dam constructed without a cutoff on permeable or semi-permeable foundations of earth or rock may lead to seepage beneath the dam creating unacceptable uplift pressures and causing instability.

Soil Mechanics Flow Nets page 2 Drainage blanket Phreatic line Unsaturated Soil z Flow of water x Fig. In the flow net there are 4-7 flow channels and 15 equipotential drops.

Use this procedure to estimate seepage quantity and distribution of pore water pressures in two-dimensional flow.

Draw trial flow net See Cedergren Seepage Drainage and Flownets – posted on web. The position of the phreatic line influences the stability of the earth dam because of potential piping due to excessive exit gradient and sloughing due to the softening and weakening of the soil mass as if it touches the downstream slope or intersects it. Chapitre 10. An earth dam constructed without a cutoff on permeable or semi-permeable foundations of earth or rock may lead to seepage beneath the dam creating unacceptable uplift pressures and causing instability. 1 Réseaux d'écoulement . Flow nets are applicable for the study of cutoff walls and wellpoints, or shallow drainage installations placed in a rectangular layout whose length in plan is The seepage is given by: q=kh 4-7 = x x = 3-1 x 10-5m3/s (per m) The pore water pressure is calculated at the points of intersection of the equipotentials with the base of the dam.