Phreatic line ppt. Magmatic eruptions .

Phreatic line ppt. Lecture 17 Design and Construction of Dams Earth Dams Phreatic Line with Phreatic Lines: Pore pressures and external water pressures can be generated on the basis of phreatic lines. A flownet graphically represents seepage paths through interconnected soil voids as flow lines and The phreatic surface is best shown in Figure 9. You can use PowerPoint drawing tools to create lines and free form shapes. This document discusses how to draw the phreatic line in an earth dam. 0. Understanding the phreatic line variation inside the landslide is of significant importance for the analysis and evaluation of slope stability. The Water Table can also be used to define ponded water above the slope surface. The phreatic surface should be kept at or below the downstream toe. 3 Line of Constant Pore Water Pressure Sometimes a portion of saturated soil is in contact with air and so the pore water pressure of the water just beneath that surface is atmospheric. This video explains why that line, called the Phreatic Line, is so important. Two Sep 28, 2017 · The equation of the phreatic line ω (x) is fitted by the measured data of water level in phreatic line observation holes. You cannot draw a phreatic line like that. Calculation of seepage face is Embankment lecture 4 - Download as a PDF or view online for free Phreatic Line and Horizontal Drain In Earth fill Dams Earth dams are generally built of locally available materials in their natural state with a minimum of processing. With a phreatic line it is understood that water pressures above the line are zero and increase linearly with depth below the line. 2 6, where we have chosen to draw the contours in the vicinity of zero pore pressure. 25 Where full lines do not appear, this case is not appreciably different from Case 2 Case 2: Critical circle passing The top flow line of a saturated soil mass below which seepage takes place, is called the Phreatic line. youtube. Mar 17, 2012 · ERUPTIONS Phreatic and Phreatomagmatic Eruptions Phreatomagmatic Eruptions A phreatomagmatic eruption is an explosive water-magma interaction. This document discusses seepage analysis through permeable media like soil. Flow lines to be nearly horizontal Hydraulic gradient of the flow is equal to the slope of the phreatic surface Oct 4, 2020 · Phreatic line It is the top flow line of saturated soil mass is called the phreatic line. The following is the procedure for locating the phreatic line graphically by using CASAGRANDE’S METHOD OF DETERMINING PHREATIC LINE IN A DAM WITH HORIZONTAL DRAINAGE FILTER: Apr 27, 2013 · Some concept of Advance Geotechnological Engineering are An-isotropic Clay, Atterberg Limits, Axial Extension Tests, Circularly Loaded, Clay Mineral With Three-Layer Sheets, Definition of Stress Path, Effective Stress. A phreatic surface is also a line of constant (zero) pore water pressure as discussed below. In this context, the expression of normal stress on the slip surface under seepage forces is deduced, and a procedure for obtaining the safety A simple numerical model for estimating a phreatic surface in an earthen dam is presented. Thanks Aug 23, 2018 · Learn how to draw in PowerPoint in this short tutorial. Homogeneous earth dams are built whenever only one type of material is economically available. This chapter discusses various methods for determining the phreatic surface. Jan 23, 2024 · A seepage field, influenced by rainfall and reservoir water level fluctuation, is closely associated with the stability of the reservoir landslide. It provides the following key points: 1) The phreatic line can be drawn using a parabolic concept, with the focus point and directrix of the parabola determining the Line of Seepage or Prelatic Line in Earthen Dams • Line of Seepage or the Phreatic line of saturation line is defined as the line within the dam section below which there are positive hydrostatic pressure in the dam. In the earth dam, the phreatic line shapes like a parabola. Flow The top flow line of a saturated soil mass below which seepage takes place, is called the Phreatic line. Unsaturated Zone, Vadose Zone, Soil Moisture Zone, Zone of Aeration – rock, water and air Capillary Fringe – region above water table where water rises due to capillary forces in the porous medium. The experiment involves constructing a model earthen dam in the tank out of sand and observing the flow lines as water is introduced upstream. 10. 2. The paper discusses the principles of seepage failure in embankment dams, focusing on the applicability of Darcy's Law and the permeability of soil. The numerical approach is based upon the Complex Variable Boundary Element Method (CVBEM). e. The sand model runs are carried out with horizontal, vertical and toe filter on three different Oct 26, 2022 · Then, the phreatic line level remains higher than the river water level, which is assumed to be the cause of the instability of the slope. In the case of an existing slope, the phreatic surface can be deter mined from the subsurface investigation with adjustments for seasonal changes. The soil is saturated below this line and pressure on this line is atmospheric. Model output was also used for embankment drain capacity design. According to previous studies, the inclusion of seepage forces typically reduces stability. Oct 16, 2018 · View Notes - Dam Lecture 17 - Determination of Phreatic Line in Earth Dam. 7K subscribers 344 Dec 5, 2024 · Phreatic Line: The top flow line of a saturated soil mass below which seepage takes place, is called the Phreatic line. Saturated Zone, Phreatic Zone – rock and water Water Table • Top of saturated zone • Depressed version of topography Jul 21, 2016 · The condition in which the phreatic line reaches the protected side is in itself a hydraulic failure of the levee performance and represents a dangerous situation that affects the levee reliability, as it may lead to consequent critical conditions for soil particles erosion. By expanding the CVBEM approximation geometric functions into a first order Taylor series, the unknown phreatic surface location geometrics can be approximated without iteration by solving a single matrix system. The top width of the dam depends on the height and type of material used. 6 shows the relation between the relative permeability coefficient (k1/k2) and the phreatic line level at the upstream side of the inner zone (y1/h Feb 4, 2020 · There is a well defined line of saturated earth that runs from inside the dam at the edge of the water to the outside of the dam, at the Toe of Slope where the outer slope of the earthen embankment meets the level ground below the water being impounded. 2. Main points of this lecture are: Plotting of Phreatic Line, Seepage Through Earth Dams, Entrance, Discharge, Transfer Conditions, Line of Seepage, Earth Dams, Filter Design The phreatic zone, below the phreatic surface where rock and soil are saturated with water, is the counterpart of the vadose zone, or unsaturated zone, above. In this lecture, We will learn about the concepts and principles of Seepage analysis. Equipotentials Lines of constant head, h (x,z) Equipotential (EP) 4 Graphical representation of solution 2. 8), the phreatic line starts tangentially with the water surface. Jun 9, 2021 · Figure 3: Dewatering by means of the phreatic method Groundwater flow analysis The FE method can also be used in PLAXIS for groundwater flow modeling to analyze hydrogeological problems, such as dewatering, in multilayer soil profiles. Based on the obtained phreatic line, the expression of . pptx - Free download as Powerpoint Presentation (. This paper aims to propose a new analytical solution for the phreatic line of a wet tailings pond to predict the phreatic line in the tailings pond. The free water surface line of the seepage flow in tailings dam is called phreatic line. Hydrostatic pressure acts below the phreatic line whereas atmospheric pressure exists above • Flow Net Embankment Flow Net Phreatic Line Unconfined Embankment Aquifer Phreatic Line (Dupui t ' s assumption) Confined Aquifer o f f i n i t e length and uniform thickness Blanket-Aquifer, Continuous Blanket-Aquifer, and Discontinuous) Continuous and Discontinuous) Aug 7, 2024 · This research reveals that the tailings clay lens within the dam body increases the hydraulic gradient in its vicinity due to its low permeability and raises the phreatic line. Nov 23, 2011 · 16. Key concepts such as hydraulic gradients, phreatic lines, and (B) stability number Typical cross section showing various cases represented in chart considered in Zone B by full lines Case 1: The most dangerous of the circles passing through the toe, represented by full lines in chart. 4. Below the phreatic line, the seepage takes place. Learn how to design earthen dams & determine the phreatic line for optimal stability. To this aim, geometric and empirical criteria were developed in the past to identify the location of the phreatic line (e. Mar 1, 2021 · This line is called phreatic line or seepage line. The hydraulic force acting on the part fgBf is D, whose action point is the centroid of the area. A Steady state groundwater flow is a flow analysis in which the boundary conditions and permeabilities are considered to give you the exact pore pressure distribution (psteady again). The second and third question were used to study the effect of different hydraulic loads on the progression of the phreatic line in the dike compared to the prescribed schematic estimations of the phreatic line. Investigates the effect of core characteristics on seepage discharge and the phreatic line. Mar 3, 2025 · Because of that, your wall is above the phreatic level and therefore has no pore pressures at all. Fig. For an earthen dam, the phreatic line approximately assumes the shape of a parabola. 1 FLOW NETS In the stability analysis of slopes, particularly those related to earth dams, it is necessary to estimate the location of the phreatic surface or the line of seepage. That is, you can, but it's wrong: it will lead to a sudden jump in pore pressures below the wall that in reality can't exist. Regarding the soil mass above the phreatic line with negative pore water pressure, seepage theories for unsaturated soil are required and the coefficient of permeability varies with Nov 1, 2023 · Figure 10: Phreatic surface with saturated-unsaturated flow method The difference in phreatic surface elevation is due to conservation of mass flow. Seepage Analysis - Free download as Powerpoint Presentation (. Phreatic line follows the path of base parabola. In presentations about phreatic water, utilizing a PowerPoint (PPT) template can enhance the clarity and impact of your information. Schafferank, 1917, Casagrande, 1940, Kozeny, 1931, USACE, 1993). For stormwater management ponds and sediment basins, the phreatic line star ing elevation shall be the 10-year water surface elevation, not the normal pool ele Phreatic line/Seepage line in earth dams, dam with and without filter, slope stability of embankment dams In this lecture video, I am going to discuss phreatic line in earth dam, the discharge Aug 13, 2025 · The phreatic line is the lifeline of a wet tailings pond and a crucial factor affecting its stability. Phreatic Line: The top flow line of a saturated soil mass below which seepage takes place, is called the Phreatic line. Phreatic line || definition & procedure to draw phreatic line in earthen dam|| seepage numerical Civil engineering in bengali 7. pdf from ECV 517 at Kenyatta University. SEEPAGE CONTROL: Seepage is the continuous movement of water (from u/s to d/s face of dam). Calculation of seepage face is highly non linear. IRRIGATION ENGINEERING. The document discusses methods for determining the phreatic line or seepage line in an earth dam with a horizontal filter. Casagrande observed that the shape of this top flow line is close to a parabola for most of its length and deviates from parabola only at the upstream and downstream faces. Jun 10, 2025 · The resulting phreatic line was lower, and the FoS increased to 1. All of them work differently. May 6, 2022 · 28. nt where the normal pool elevation meets the upstream slope to a point where this line intersects the invert of the pipe conduit or bottom of the cradle, whichever is wer. 62K subscribers Subscribed Nov 1, 2020 · When dealing with river levees, one of the most important aspects is the identification of the phreatic line. Jun 9, 2017 · 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. In the pure saturated flow case, the seepage occurring above the phreatic surface is ignored. [2] Casagrande's graphical method assumes the phreatic line is a base parabola with its focus at the starting point of the filter. Unconfined aquifers are also called phreatic aquifers because the phreatic surface provides their upper boundary. TUTORIAL PROBLEMS A canal and a river run parallel, an average of 60 m apart. txt) or view presentation slides online. To add a Water Table to your model: Select Add Water Table from the toolbar or the Boundaries menu. 2 2. The area of the part fgBf modeled by the phreatic line, the slope, and the sliding face is W. The hydrostatic pressure represents the atmospheric pressure, which is equal to zero at the face of phreatic line. zero pressure line)? I can view the phreatic surface but don't know how to obtain the x/y coordinates of the zero pressure line. Plotting of Phreatic Line In order to draw flow net, it is first essential to find the location and shape of Phreatic line or top flow line separating Saturated and Unsaturated Zones. In the saturated-unsaturated case, seepage occurs above and below the phreatic surface. Effective stress is the difference between total stress and neutral stress (pore water pressure). The d Flow Net Construction Unconfined Flow System Phreatic line unknown (air-water interface) B Phreatic surface unknown D Impermeable foundation Feb 12, 2018 · Flow Net The flow net is a network formed by the flow lines and is the pattern which shows the path of flow as well as the dissipation of potential in a system of seepage through a layer of soil. This is not an equipotential line. In the current slope stability analysis, the phreatic line was observed to drop and subsequently reach a steady-state condition below the ground surface. If the slope has not been constructed and is quite complex in The phreatic surface is best shown in Figure 6, where we have chosen to draw the contours in the vicinity of zero pore pressure. Explore theories and models in geotechnical engineering courses. Meaning of Phreatic Line: Phreatic line is also known as the seepage line or saturation line. Apr 15, 2023 · The phreatic line of glycerin seepage through a rectangular dam with a height of 6 m and a width of 4 m is taken as an example to demonstrate the feasibility and accuracy of neural network prediction methods [45]. Drawdown test Needs a well-defined water table and confining boundary Must be able to pull down water table and create flow (phreatic line = uppermost flow line) 18. Dec 5, 2016 · Rainfall and reservoir water level fluctuations are the main external factors of landslides in the Three Gorges Reservoir area. com/playlist?list=PLhs2wycMV2yivJnTnQOC5XQZaCH_cjCMw Jan 28, 2006 · Hi everybody, I have a very basic question. Solution Axi-symmetric problem By integration of Darcy s Law, 19. Specific subtypes of eruptions like Hawaiian, Strombolian, Vulcanian, and Plinian eruptions are also discussed. The phreatic surface within a dam can be controlled by properly designed cores or walls. pptx), PDF File (. . Feb 6, 2018 · On the basis of the Boussinesq unsteady seepage differential equation, a new simplified formula for the phreatic line of slopes under the condition of decreasing reservoir water level is derived by m A Phreatic will base the psteady on the water line you draw (or WaterConditions defined), but no flow is run. Types of slope Title: Soil Mechanics A 1 Flow Nets 2 Flow through a Dam Phreatic line Unsaturated Soil Drainage blanket Flow of water z x 3 Graphical representation of solution 1. Show events, milestones or steps in chronological order with these Timelines for Google Slides and PowerPoint, they are 100% editable and ! The objective of the Pre-Final/Final Design seepage analysis was to evaluate embankment seepage, investigate control of internal erosion and piping by limiting exit gradients, and preventing the softening of fill by controlling the position of the phreatic line within the embankment. Flow lines Paths followed by water particles - tangential to flow Phreatic line Flow line (FL) Equipotential (EP) 5 Jun 15, 2021 · Compares the performance of SEEP2D and SEEP/W numerical models in simulating earth dams with internal cores. Moreover, In order to comprehend the seepage utilizing GTS NX software, we will Calculate the seepage flow rate that occurs in the ground including the embankment. In the case of an existing slope, the phreatic surface can be determined from the subsurface The document provides information about volcanic eruptions, including: 1. Hydrostatic pressure acts below the phreatic line whereas atmospheric pressure exists above the phreatic line. As the tailings clay lens approaches the dam body, the phreatic line tends to escape along the upper part of the lens towards the dam surface. Apr 1, 2012 · PDF | On Apr 1, 2012, Reza Ziaie moayed and others published Evaluation of phreatic Line in Homogeneous Earth Dams With Different Drainage System | Find, read and cite all the research you need on SEEPAGE ANALYSIS:(PHREATIC UNE IN EARTH DAM) Casagrande assumed the phreatic line to be a base parabola with its focus at F, the starting point of the filter FE. pdf), Text File (. Understanding phreatic water is vital for various applications, including environmental studies, water resource management, and engineering projects. Field testing drawdown test 17. Assuming a point P on the phreatic surface, with known location determined by length L and height H, the seepage face l and the phreatic surface are found through a set of nonlinear equations. It defines different types of slopes as natural, man-made, infinite and finite. 11 Simulated result of phreatic line with toe drain SEEP/W distinguishes itself from the other software in line for the seepage analysis by providing the value of the exit gradient for each of the distinct nodes and by visualizing equipotential lines and flow lines for the supplied model. I need to copy that phreatic 4. Mar 1, 2025 · This process significantly impacts the dam's stability by altering pore water pressure, shifting the position of the phreatic line, and compromising overall safety [16]. When β is 180 0 phreatic line meets the discharge face exactly as the base parabola. Jan 10, 2025 · Learn about two-dimensional flow of water through soil, including steady-state and transient seepage, laplace equation, flow nets, and practical solution methods. This line separates a saturated soil mass from an unsaturated soil mass. Specific eruption styles like Hawaiian, Strombolian, Vulcanian, Pelean, Plinian, Surtseyan design of earth dam - Free download as Powerpoint Presentation (. The first sub-question provided insight into the influences of soil and hydrological factors on the phreatic line. this playlist covers the video lectures of GTE GTE - AEE/AE/SSC JE (TELUGU): https://www. Magmatic eruptions Figure 1. Expert tips, guides, and best practices for constructions Sep 1, 2012 · The soil mass below the phreatic line is under saturated conditions with positive pore water pressure, then seepage theories for saturated soil are applicable. Based on this, by integrating Darcy’s law of infiltration and the energy equation, the differential equation for the phreatic line was derived We would like to show you a description here but the site won’t allow us. It outlines methods for determining the coefficient of permeability, both in laboratory and field settings, and provides solutions to calculate seepage discharge through earth dams. Also we will discuss the phreatic line theory of a dam body. 3. [1] This line separates a saturated soil mass from an unsaturated soil mass. It describes the different types of volcanic eruptions such as magmatic, phreatomagmatic, and phreatic eruptions. Are there any recommended techniques or modeling approaches in PLAXIS that can be used Jul 26, 2025 · GeoStudio | PLAXIS Forum - - Hi, I did one seepage analysis and have the phreatic surface from the output. Needles with dye are I have modelled a dyke section for normal water level conditions (the phreatic line just being beneath the ground level) and I aim to model this dyke section for raised water level conditions (like raising 1m in each stage) so as to understand the stability under higher river levels during floods, so want to know how should I be modelling the various stages of raising water levels in Plaxis. 8 Properties of Flow Net The following are the 8 properties of flow net: The flow lines and equipotential lines meet at right angles to each other Two flow lines never cross each other. Hydrostatic pressure acts below the Apr 15, 2023 · The phreatic line of glycerin seepage through a rectangular dam with a height of 6 m and a width of 4 m is taken as an example to demonstrate the feasibility and accuracy of neural network prediction methods [45]. Quick sand condition occurs when upward seepage pressure equals the submerged soil weight, causing zero effective stress and losing of shear strength. The higher the phreatic line of Abstract This investigation concerns to study the free water surface (the phreatic line) of the unconfined steady flow through a homogenous earth dam based on an impervious base provided with three types of filter which control the water movement through the earth dam through the sand mode. The water in the tailings pond constantly seeps through the voids between the tailings particles and flows downstream, thus forming the seepage flow. Suggests design equations for the core types studied. ppt / . Such types of analysis can be run in either a steady-state model or in a time-dependent model. 18—still higher than the initial analysis. g. The result on land are usually big holes in the ground. Modified Seepage Analysis: Imposed zero-pressure boundaries on the slope face to match the initial phreatic line. Seepage occurs due to gravity-driven flow of water from high to low pressure areas. The findings May 1, 2021 · The distribution of the phreatic line in a dam was determined by the temperature detection curve obtained from OFDR, which could provide a reference for future applications of OFDR technology for seepage monitoring of embankment dams. 1. The causes and mechanisms of different types of eruptions are explained. Key terms used in slope stability are defined, including slip zone, slip plane, sliding mass and slope angle. The main types include magmatic eruptions driven by gas decompression, phreatomagmatic eruptions driven by gas compression, and phreatic eruptions caused by steam superheating. Common causes of slope failure like erosion, seepage, drawdown, rainfall, earthquakes and external loading are described. In this article, we are going to explain each type severely. The instability occurs during the drawdown when the phreatic level in the ground remains at a high level due to the ground’s poor permeability, causing the weight of the soil to remain high. It ranges from Jun 13, 2021 · Phreatic line meets differently to the different types of discharge faces. Key steps include slowly filling the upstream and downstream pools to stabilize the dam without collapse. The document discusses the design considerations for earth dams, including: 1. We will understand the theoretical methods to determine seepage deeply. Dec 28, 2021 · Microsoft PowerPoint lines include straight line, arrow, double arrow, elbow connector, curved connector, curve, Freeform, and scribble. The hydrostatic pressure is acts below the phreatic line. Covers downstream inclined cores, which have not been considered previously in the literature. A higher phreatic line increases pore pressure, reducing the dam material's effective stress and diminishing its shear strength. In Figures 2 to 7, the position of the phreatic line (that is, the line corresponding to the phreatic surface lying above the saturated zone when seen in a vertical plane) has been marked in the respective figures. To improve the analysis of slope stability under the combined effect of reservoir water level fluctuations and rainfall, a simplified method for phreatic line calculation of slopes is proposed in this study. At the entry point, the phreatic line must be normal to the upstream face since the upstream face is a 100% equipotential line. Sep 5, 2024 · Earthen Dams on the phreatic line is atmospheric and pressure below the phreatic line is hydrostatic. On the basis of the Boussinesq unsteady seepage diferential equation, a new simplified formula for the phreatic line of slopes under the condition of decreasing reservoir water level is derived by means of the Laplacian matrix and its inverse transform. This document describes an experiment to visualize seepage through an earthen dam using a permeability tank apparatus. This phreatic surface compares well with the analytical phreatic surface calculated by Harr (1962), shown in Figure 9. May 2, 2020 · An infiltration gallery is a subsurface source of water used for a water supply system whose structure is like a horizontal drain that is positioned below the water table so that it collects the Phreatic line through the zoned earth dam Fig. [1] The phreatic line separates the saturated and unsaturated zones, with hydrostatic pressure being atmospheric at the line. Feb 6, 2018 · On the basis of the Boussinesq unsteady seepage differential equation, a new simplified formula for the phreatic line of slopes under the condition of decreasing reservoir water level is derived by m How can I obtain he x/y coordinates of the calculated phreatic surface (i. The document provides an overview and tutorial for the PLAXIS software, which is used to analyze geotechnical issues such as soil behavior and settlement. 10: Phreatic surface with saturated-unsaturated flow method The difference in phreatic surface elevation is due to conservation of mass flow. Currently, most of the boundaries of phreatic line analytical models and the hydrological conditions are Phreatic lines - Seepage through Soil for Engineering Lead GATE - ME,XE,PI 56. The upper surface of this stream of percolating water is known as the phreatic surface. This document provides an overview of slope stability and analysis. A procedure is Dec 2, 2023 · Tailings dam drainage is a technique of setting up drainage facilities in a tailings dam to enhance stability of dam body. When the dam embankment is homogeneous or when the downstream zone is of questionable permeability, a horizontal drainage blanket is Plaxis Tutorial 01 - Free download as Powerpoint Presentation (. The phreatic surface is best shown in Figure 9. The height of the dam is governed by the highest flood level and freeboard. ppt), PDF File (. Phreatic line The top flow line of a saturated soil mass below which seepage takes place, is called the Phreatic line. Hydrostatic pressure acts below the Chapter 62 - Shape of Phreatic Line in Earth Dam without FilterA dam is a barrier that restricts the flow of water and can be used to collect the water and t Hydrostatic pressure acts below the phreatic line whereas atmospheric pressure exists above the phreatic line. Add Water Table A Water Table (phreatic surface) can be used for calculating pore pressure when the Groundwater Method in Project Settings is set to Water Surfaces. There are several different types of volcanic eruptions that are classified based on their eruption dynamics and behavior. The FoS reduced to 1. In the stability analysis of slopes, particularly those related to earth dams, it is necessary to estimate the location of the phreatic surface or the line of seepage. Is there any difference between piezometric level and phreatic surface? If so what is it and how they are determined. Evaluates the most effective earth dam core shape. It is not an equipotential line, but a flow line. 36. In case of higher order elements the problem is more difficult due to irregular distribution of discharge at nodes. Enter the vertices of the Water Table as described Jan 30, 2014 · Abstract In the stability analysis of slopes, particularly those related to earth dams, estimating the location of the phreatic surface, or the line of seepage, is necessary. Phreatomagmatic eruptions occur when hot magma comes into contact with water, either as groundwater, lakes or oceans. Seepage is the flow of water through soil. For other entry condition (Fig. It is defined as an imaginary line within the dam section, below which there is positive hydrostatic pressure, and above there is negative hydrostatic pressure in the dam section. This phreatic surface compares well with the analytical phreatic surface calculated by Harr (1962), shown in Figure 2. Flow nets can be used to model seepage by showing flow lines and equipotential lines. However, for the purpose of this analysis, I would like the phreatic line to be maintained at the ground surface, representing a fully saturated condition. 8dc7aa iia d6nae tk6kypz tfk el xj6d tyci fm ntby