The number of potential drops in a flow net is denoted by nd. Flow net a combination of a number of flow lines and equipotential lines. The following set of lecture notes cover every major topic discussed in class. Flow net soil mechanics permeability earth sciences scribd. The method is often used in civil engineering, hydrogeology or soil mechanics as a first check for problems of flow under hydraulic structures like. Definition, compaction fundamentals, moisture density relationship, compaction standard.
A line along which a water particle moves through a permeable soil medium. How to draw a flow net by hand and use it to estimate water flow through soil. Part ii1 soil composition, index properties and soil classification pdf 1. In the flow net there are 47 flow channels and 15 equipotential drops. Pdf geotechnical engineering gate solved questions. Easyengineering provide you the best collections of anna university. Introduction the purpose of this course is to provide the learner with easytounderstand introductions to the subjects of geotechnical engineering and soil mechanics. So, in the last lecture basically we have talked about the seepage in soil and there. Flow lines represent the path of flow along which the water will seep through the soil. Seepage soil mechanics and foundation engineering book.
Flow nets flow line a line along which a water particle will travel from upstream to the down stream side in the permeable soil medium equipotential line a line along which the potential head at all points is equal. If soil is anisotropic and coefficient of permeability in x and z direction is not same, the laplace equation is modified as. Mathematical expressions for the flow are written for each of the elements, considering boundary conditions. Soil mechanics arnold verruijt delft university of technology, 2001, 2006 this is the screen version of the book soil mechanics, used at the delft university of technology. Graphical construction used to calculate groundwater flow through soil. Soil mechanics flow nets page 3 it is also useful in visualising the flow in a soil to plot the flow lines 3 blue lines noted fl, these are lines that are tangential to the flow at a given point and are illustrated in figure 2.
Soil mechanics flow nets page 2 drainage blanket phreatic line unsaturated soil flow of waterz x fig. A flow net consists of two sets of lines which must always be orthogonal perpendicular to each other. The path which a particle of water follows in its course of seepage through a saturated soil mass is called a flow line. For more help in uses of flow net click the button below to submit your homework assignment. Understand influence of soil structure and mineralogy on soil behavior. Draw a coarse net which is consistent with the boundary conditions and which has orthogonal equipotential and flow lines. Cedergren 191196 received his bsce from the the university of washington in 1938 and ms in soil mechanics from harvard in 1939, under prof. Seepage flow, flow nets in anisotropic medium, uplift pressure in. A flow net is drawn by hand as a demonstration, and various calculations including head, pre. Understand how stresses are transferred through soils. We can use the flow net to identify areas where critical gradients may occur and determine the magnitude of the gradient at those locations stress caused in soil by flow j i. They are independent of the permeability of soil and the head causing flow. Flow net construction and use purpose and scope the flow net is an excellent tool for evaluating the effects of seep age when adequate knowledge of embankment andor foundation conditions is available.
In order to represent these values, contours of equal head are drawn. Flow net properties and applications the constructor. Clear explanations of darcys law, permeability, and other core concepts. Introduction to soil mechanics geotechnical engineering dr. This note contains guides for the construction and use of flow nets. A flownet is a graphical representation of twodimensional steadystate groundwater flow through aquifers construction of a flownet is often used for solving groundwater flow problems where the geometry makes analytical solutions impractical. Ce6405 soil mechanics syllabus notes 2 marks with answers. Pdf ce8491 soil mechanics sm books, lecture notes, 2.
Ce8491 syllabus soil mechanics regulation 2017 anna university free download. Ce8491 soil mechanics sm syllabus, books, lecture notes, part a 2 marks with answers, important part b marks questions, direct 16 mark questions, important part c 15 marks questions, local authors pdf books, question bank with answers key, anna university ce8491 soil mechanics sm question papers collection. The laplace equation presented in previous lesson lesson 19 is valid for isotropic soil. Between the upstream and downstream equipotentials the total head loss is 400 m. Seepage percolation the movement of gravitational water. It is a curvilinear net formed by the combination of flow lines and equipotential lines. Soil mechanics terzaghi stated in his book theoretical soil mechanics 1943. There is another type of flow net that is extremely difficult to construct by graphical means. Ahmed alobaidi 14 procedure for drawing flow nets at every point x,z where there is flow, there will be a value of head hx,z.
Uses of flow net assignment help homework help online live. The resulting system of equations is solved by computer to obtain the flow pattern 2. The flow of water through soil exerts a force on the soil. Flow nets are drawn based on the boundary conditions only. Either flow lines or equipotential lines are smoothly drawn curves. Groundwater university of the west of england, bristol. June 1937, also published in contributions to soil mechanics, 19251940. Geotechnicalpressure under dam with flow nets duration. Unified and indian standard soil classification system. Introduction to flow nets simple problems sheet pile and wier. A surface on which the total head is fixed for example, from the level of a river, pool, reservoir is an equipotential. To develop suitable soil testing devices and soil testing methods. Understand basic principles of flow through porous media including darcys law, the equation of continuity, seepage forces and flow nets. A surface across which there is no flow for example, an impermeable soil layer or an impermeable wall is a flow line.
The level of the subjects covered are first year university level and will be easily followed by anyone studying, practicing, or simply interested in, civil engineering. Three different scenarios, of identical soil specimens subjected to different flow conditions, are shown in fig. Determine the head at the inlet and outlet of the flow net. Flownets example soil mechanics and geotechnical engineering. Introduction to soil mechanics geotechnical engineering. The flow of water through a soil can be represented graphically by a flow net, a form of curvilinear net made up of a set of flow line intersected by a set of equipotential lines.
Ce8491 syllabus soil mechanics regulation 2017 anna university. To develop rational soil sampling devices and soil sampling methods. For flow problems that involve both saturated and unsaturated flow, steadystate flow nets are usually derived by numerical simulation. Soil mechanics note 5 flow net construction and use. This lecture talks about flow nets and how to draw them by hand. This view is looking towards right abutment mid may 1976. How to draw flow net seepage by hand soil mechanics. Soil mechanics flow nets page 7 figure 7 constant pore water pressure boundary 10. The coefficient of permeability of the foundation soil is 25 x 105 ms. It is a curvilinear net formed by the combination of flow lines and. The topics that are covered in this pdf containing geotechnical engineering previous year gate solved questions are.
The equation is used in the construction of flow net. Concepts are thoroughly explained, and the educated user will find few. This method is usually used in soil mechanics, geotechnical or civil engineering as an initial check for problems of water flow under hydraulic. Threephase system and phase relationships, index properties. Properties and application of flow net are explained in this article. Soil mechanics exam hydraulic conductivity and flow nets 27 terms. A flow net analysis assists in the design of an efficient boundary shapes.
Associate professor, lab of soil mechanics, department of environmental. A flow net is a graphical representation of flow of water through a soil mass. The rate of filling is usually limited to no more than 1 foot per day. Seepage problem occurs in all earthen dams, retaining walls and foundations on permeable soil. Unit ii soil water and water flow soil water static pressure in water effective stress concepts in soils capillary stress permeability measurement in the laboratory and field pumping in pumping out tests factors influencing permeability of soils seepage introduction to flow nets simple problems. Newly completed teton dam as it appeared in mid may 1976, as the reservoir was filling at the rate of 3 feet per day. To really understand it, mastery of hydraulics and soil mechanics is required, and some knowledge of hydrology and hydrogeology is helpful. To collect and classify soils and their physical properties on the basis of fundamental knowledge of soil mechanics.