Table of Contents
How do you draw a flow net?
How do you draw a flow net by hand?
What is flow net diagram?
A flow net is a graphical representation of two-dimensional steady-state groundwater flow through aquifers. Construction of a flow net is often used for solving groundwater flow problems where the geometry makes analytical solutions impractical.
What are the essential required to draw a flow net?
What are the essentials, required to draw a flow net? Solution: In order to draw the flow net, it is first essential to find out the location and shape of phreatic line and top flow line separating the saturated and unsaturated zones.
What is NF and ND?
Nd = number of potential drops Nf = number of flow channels h = total head loss q = total quantity of unit flow.
What is use of flow net?
To determine the amount of seepage and upward lift pressure below hydraulic structure. Once the flow net is constructed, the same one applies to flows at different discharges. A flow net analysis assists in the design of an efficient boundary shapes.
What are the components of flow net?
A flow net consists of two sets of lines which must always be orthogonal (perpendicular to each other): flow lines, which show the direction of groundwater flow, and equipotentials (lines of constant head), which show the distribution of potential energy.
What is Flow Net in geotechnical engineering?
A Flow net is a graphical representation of flow of water through a soil mass. It is a curvilinear net formed by the combination of flow lines and equipotential lines.
What is phreatic line in earth dam?
The top flow line of a saturated soil mass below which seepage takes place, is called the Phreatic line. Hydrostatic pressure acts below the phreatic line whereas atmospheric pressure exists above the phreatic line. For an earthen dam, the phreatic line approximately assumes the shape of a parabola.
Who was the first to give a graphical method of flow net construction?
3. Who was the first to give a graphical method of flow net construction? Explanation: The graphical method of flow net construction first given by Forchheimer in 1930, based on trial sketching.
What method was suggested by Casagrande for determining the phreatic line?
Explanation: Graphical method was used by Casagrande for the determination of the phreatic line using flow net.
What is permeability coefficient?
Definitions. The coefficient of permeability of a soil describes how easily a liquid will move through a soil. It is also commonly referred to as the hydraulic conductivity of a soil. This factor can be affected by the viscosity, or thickness(fluidity) of a liquid and its density.
Why does piping occur in soil?
Internal erosion is the formation of voids within a soil caused by the removal of material by seepage. Piping is induced by regressive erosion of particles from downstream and along the upstream line towards an outside environment until a continuous pipe is formed.
What is a critical hydraulic gradient?
Critical hydraulic gradient is defined by the hydraulic gradient where particles start to outflow from soil samples. The determination of the critical hydraulic gradient of internal erosion is based on the occurrence of “sand boil” or other indicating phenomena of seepage failure.
What are the primary uses for calculating and drawing flow nets?
Question: QUESTION 5 What are the primary uses for calculating and drawing flow nets? Calculating hydraulic conductivity of soil. Calculating seepage. Calculating pumping equilibrium ratios.
What are the limitations of flow net?
The flow net analysis cannot be applied in the region closed to the boundary where the effects of viscosity are predominant. The flow net is not applied to sharply diverging flow , as the actual flow pattern is not represented by the flow net.
What is the measurement of volumetric flow?
Volumetric flow is the measure of a substance moving through a device over time. Standard units of measurement for volumetric flow rate are meters3 /second, milliliters/second, or feet3/hour.
Which of the following are used to determine flow net?
Application of flow net are as follows: Determination of hydrostatic pressure. Determination of seepage pressure. Determination of exit gradient.
What is dam seepage?
Seepage flow in the dam is defined as the movement of water from the upstream side of the dam to the downstream side through embankment of below the foundation or base. Seepage in earth dam (source : www.geoengineer.org) The seepage problem is most commonly found in earthen embankment dams.
What is meant by gravity dam?
A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by using only the weight of the material and its resistance against the foundation to oppose the horizontal pressure of water pushing against it.
What is exit gradient?
The disturbing force at any point is proportional to the gradient of pressure of water at that point (i.e. dp/dl). This gradient of pressure of water at the exit end is called the exit gradient. In order that the soil particles at exit remain stable, the upward pressure at exit should be safe.
What are the properties of flow net Mcq?
8 Properties of Flow Net The flow lines and equipotential lines meet at right angles to each other. Two flow line never cross each other. Two equipotential lines never cross each other. Flow and equipotential lines are smooth curves. The quantity of water flowing through each flow channel is the same.
What is graphical method?
Graphical method, or Geometric method, allows solving simple linear programming problems intuitively and visually. This method is limited to two or three problems decision variables since it is not possible to graphically illustrate more than 3D.
What are uses of flow net Mcq?
Solution: A flow net can be utilized for determination of seepage, seepage pressure . hydrostatic pressure, and exit gradient.
When the reservoir is full dam is most likely to slide of its?
Explanation: The D/s slope is most likely to slide when the reservoir is full.
What is the recommended formula for top width of a very low dam?
What is the recommended formula for top width of a very low dam? A = H/5 + 3 where H is the height of the dam.
What are the features required for classifying a soil component as Boulder?
Explanation: For a soil component to be a boulder, size range must be of average diameter more than 30cm and shape of round to angular and bulky hard.
How is permeability calculated?
Permeability is measured on cores in the laboratory by flowing a fluid of known viscosity through a core sample of known dimensions at a set rate, and measuring the pressure drop across the core, or by setting the fluid to flow at a set pressure difference, and measuring the flow rate produced.
Is sand impermeable?
Gravel and sand are both porous and permeable, making them good aquifer materials. Gravel has the highest permeability.
How can you reduce the permeability of soil?
It is common practice to alter the soil structure to reduce permeability, for example, in irrigated agriculture through the puddling of rice fields and in civil engineering through the mechanical compaction* of earthen dams. Similar practices may be applied to fish-ponds to reduce water seepage.
