{"id":3514,"date":"2024-09-04T18:51:43","date_gmt":"2024-09-04T13:21:43","guid":{"rendered":"https:\/\/study.madeeasy.in\/?p=3514"},"modified":"2025-08-13T12:06:20","modified_gmt":"2025-08-13T06:36:20","slug":"seepage-pressure","status":"publish","type":"post","link":"https:\/\/www.madeeasy.in\/study\/ce\/soil-mechanics-foundation-engineering\/seepage-pressure","title":{"rendered":"Seepage Pressure"},"content":{"rendered":"<p style=\"text-align: justify;\">When water flows through saturated soil mass, the head available is dissipated as viscous friction, producing a frictional drag in the direction of flow on the soil particles. This drag force results in seepage force on soil mass which acts in the direction of flow.<\/p>\n<p style=\"text-align: justify;\">Hence, seepage pressure is the pressure exerted by the water over the soil solids through which it percolates.<\/p>\n<p style=\"text-align: justify;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-3515 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/09\/seepage-pressure.jpg\" alt=\"Seepage Pressure\" width=\"595\" height=\"497\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/09\/seepage-pressure.jpg 595w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/09\/seepage-pressure-300x251.jpg 300w\" sizes=\"auto, (max-width: 595px) 100vw, 595px\" \/><\/p>\n<h2 style=\"text-align: justify;\">QUICK SAND CONDITION<\/h2>\n<p style=\"text-align: justify;\">For upward flow condition, effective stress at any point within the soil mass is given by<\/p>\n<p style=\"text-align: justify;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-3516 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/09\/seepage-pressure-1.jpg\" alt=\"Seepage Pressure\" width=\"107\" height=\"43\" \/><\/p>\n<p style=\"text-align: justify;\">It is clear from above equation that upward seepage pressure decreases effective stresses in the soil mass.<\/p>\n<ul style=\"text-align: justify;\">\n<li>If the seepage pressure is such that it equals the submerged weight of the soil mass, then effective stresses at that location reduces to zero. Under such condition, cohesionless soil mass losses all shear strength. Now soil mass has a tendency to move along the flowing water in the upward direction.<\/li>\n<li>This process in which soil particles are lifted over along with water is called quick sand condition. It is also known as \u2018boiling of sand\u2019 as the surface of sand looks it is boiling.<\/li>\n<li>At quick sand condition, net effective stress is reduced to zero. i.e.<\/li>\n<\/ul>\n<p style=\"text-align: justify;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-3517 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/09\/hydraulic.jpg\" alt=\"Hydraulic\" width=\"588\" height=\"106\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/09\/hydraulic.jpg 588w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/09\/hydraulic-300x54.jpg 300w\" sizes=\"auto, (max-width: 588px) 100vw, 588px\" \/><\/p>\n<ul style=\"text-align: justify;\">\n<li>The hydraulic gradient under which quick sand condition occurs is termed as critical hydraulic gradient.<br \/>\nIf void ratio and specific gravity of soil is known, then i<sub>cr<\/sub> may be given as<\/li>\n<\/ul>\n<p style=\"text-align: justify;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-3519 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/09\/hydraulic-gradient-1.jpg\" alt=\"Hydraulic Gradient\" width=\"497\" height=\"164\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/09\/hydraulic-gradient-1.jpg 497w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/09\/hydraulic-gradient-1-300x99.jpg 300w\" sizes=\"auto, (max-width: 497px) 100vw, 497px\" \/><\/p>\n<ul style=\"text-align: justify;\">\n<li>At quick sand condition, cohesionless particles of fine sand may start flowing with the water which may result in piping failure below the hydraulic structure.<\/li>\n<li>In order to prevent quick sand or piping failure, the hydraulic gradient should be less then critical hydraulic gradient. Hence factor of safety against quick sand failure or piping failure is<\/li>\n<\/ul>\n<p style=\"text-align: justify;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-3520 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/09\/piping-failure.jpg\" alt=\"Piping Failure\" width=\"456\" height=\"38\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/09\/piping-failure.jpg 456w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/09\/piping-failure-300x25.jpg 300w\" sizes=\"auto, (max-width: 456px) 100vw, 456px\" \/><\/p>\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_79_1 ez-toc-wrap-left counter-hierarchy ez-toc-counter ez-toc-light-blue ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.madeeasy.in\/study\/ce\/soil-mechanics-foundation-engineering\/seepage-pressure\/#FLOW-NETS\" >FLOW NETS<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.madeeasy.in\/study\/ce\/soil-mechanics-foundation-engineering\/seepage-pressure\/#Properties-of-Flow-Nets\" >Properties of Flow Nets<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.madeeasy.in\/study\/ce\/soil-mechanics-foundation-engineering\/seepage-pressure\/#FLOW-THROUGH-NON-HOMOGENEOUS-SECTION\" >FLOW THROUGH NON-HOMOGENEOUS SECTION<\/a><\/li><\/ul><\/nav><\/div>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"FLOW-NETS\"><\/span>FLOW NETS<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p style=\"text-align: justify;\">The entire pattern of flow lines and equipotential lines is referred as a flow net. It is the graphical solution of Laplace\u2019s equation for relevant boundary conditions. Thus, a flow net is a graphical representation of the head and direction of seepage at every point.<\/p>\n<h4 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"Properties-of-Flow-Nets\"><\/span>Properties of Flow Nets<span class=\"ez-toc-section-end\"><\/span><\/h4>\n<ul style=\"text-align: justify;\">\n<li>Flow lines (\u03c8-lines) and equipotential (\u03c6-lines) meet each other orthogonally.<\/li>\n<li>Flow lines and equipotential lines are smooth continuous curves, being either elliptical or parabolic in shape.<\/li>\n<li>Area bounded between two adjacent equipotential lines and adjacent flow lines is referred to a flow field,<br \/>\nwhich many be linear or curvilinear.<br \/>\n\u2022 For isotropic medium, flow field is approximately square.<br \/>\n\u2022 For non-isotropic medium, flow field is rectangular.<\/li>\n<li>Flow net remain unchanged if boundary conditions are not altered i.e flow net remain same for the same set of boundary conditions.<\/li>\n<li>Discharge through each flow channel is constant i.e., \u2206q<sub>1<\/sub> = \u2206q<sub>2<\/sub> = \u2206q<sub>3<\/sub> = \u2206q<sub>4<\/sub>.<\/li>\n<\/ul>\n<h3 style=\"text-align: justify;\"><span class=\"ez-toc-section\" id=\"FLOW-THROUGH-NON-HOMOGENEOUS-SECTION\"><\/span>FLOW THROUGH NON-HOMOGENEOUS SECTION<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<ul style=\"text-align: justify;\">\n<li>If there is a change in soil conditions, the flow lines are deflected at the interface of the soil with varying permeability, k<sub>1<\/sub> and k<sub>2<\/sub>.<\/li>\n<li>Let the potential drop from P to Q and from R to S be \u2206H, then<\/li>\n<\/ul>\n<p style=\"text-align: justify;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-3521 size-full\" src=\"https:\/\/study.madeeasy.in\/wp-content\/uploads\/2024\/09\/non-homogenous-section.jpg\" alt=\"Non Homogenous Section\" width=\"596\" height=\"264\" srcset=\"https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/09\/non-homogenous-section.jpg 596w, https:\/\/www.madeeasy.in\/study\/wp-content\/uploads\/2024\/09\/non-homogenous-section-300x133.jpg 300w\" sizes=\"auto, (max-width: 596px) 100vw, 596px\" \/><\/p>\n<p style=\"text-align: center;\"><a class=\"btn btn-danger\" role=\"button\" href=\"https:\/\/study.madeeasy.in\/ce\/soil-mechanics-foundation-engineering\/permeability-of-soil\/\" target=\"_blank\" rel=\"noopener\">&lt;&lt; Previous<\/a> | <a class=\"btn btn-success\" role=\"button\" href=\"https:\/\/study.madeeasy.in\/ce\/soil-mechanics-foundation-engineering\/earthen-dams\/\" target=\"_blank\" rel=\"noopener\"> Next &gt;&gt;<\/a><br \/>\n<strong> Must Read: <\/strong> <a href=\"https:\/\/study.madeeasy.in\/ce\/soil-mechanics-and-foundation-engineering\/\" target=\"_blank\" rel=\"noopener\"><strong>Soil Mechanics and Foundation Engineering<\/strong><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>When water flows through saturated soil mass, the head available is dissipated as viscous friction, producing a frictional drag in<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[957,2],"tags":[984,983,985,982],"class_list":["post-3514","post","type-post","status-publish","format-standard","hentry","category-soil-mechanics-foundation-engineering","category-ce","tag-flow-nets","tag-hydraulic-gradient","tag-non-homogenous-section","tag-quick-sand-condition"],"_links":{"self":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts\/3514","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/comments?post=3514"}],"version-history":[{"count":0,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/posts\/3514\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/media?parent=3514"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/categories?post=3514"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.madeeasy.in\/study\/wp-json\/wp\/v2\/tags?post=3514"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}