{"id":154,"date":"2020-10-12T03:48:35","date_gmt":"2020-10-12T03:48:35","guid":{"rendered":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/?post_type=chapter&p=154"},"modified":"2020-12-11T17:46:10","modified_gmt":"2020-12-11T17:46:10","slug":"void-ratio","status":"publish","type":"chapter","link":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/chapter\/void-ratio\/","title":{"raw":"3.4 Void Ratio","rendered":"3.4 Void Ratio"},"content":{"raw":"Engineering and soil mechanics professionals use the term void ratio<\/em>, e<\/em>, when describing the amount of void space in a soil or rock. The void ratio is the volume of voids divided by the volume of solids as shown in Equation 7.\r\n\r\n\r\n\r\n
<\/td>\r\n[latex]\\displaystyle e=\\frac{V_V}{V_S}[\/latex]<\/td>\r\n(7)<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nwhere:\r\n\r\n\r\n\r\n\r\n\r\n
e<\/em><\/td>\r\n=<\/td>\r\nvoid ratio (dimensionless)<\/td>\r\n<\/tr>\r\n
V<\/em>V<\/em><\/small><\/sub><\/td>\r\n=<\/td>\r\nvolume of voids (L3<\/sup>)<\/td>\r\n<\/tr>\r\n
V<\/em>S<\/em><\/small><\/sub><\/td>\r\n=<\/td>\r\nvolume of solids (L3<\/sup>)<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nThe void ratio, V<\/em>V<\/em><\/small><\/sub> \/ V<\/em>S<\/em><\/small><\/sub>, is always larger than the total porosity, V<\/em>V<\/em><\/small><\/sub> \/ V<\/em>T<\/em><\/small><\/sub>, because the value of V<\/em>S<\/em><\/small><\/sub> (the denominator of the void ratio) is always less than the total sample volume, V<\/em>T<\/em><\/small><\/sub>. Recognizing the total sample volume is equal to V<\/em>V<\/em><\/small><\/sub> + V<\/em>S<\/em><\/small><\/sub>, total porosity can be calculated from void ratio as shown in Equation 8.\r\n\r\n\r\n\r\n
<\/td>\r\n[latex]\\displaystyle n=\\frac{e}{1+e}[\/latex]<\/td>\r\n(8)<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nBoth porosity and void ratio are used to characterize the open space of soil, sediments and rocks. Groundwater professionals most commonly use total porosity or effective porosity to compare the open space of earth materials. They use effective porosity to determine the capacity of a material to store groundwater.","rendered":"

Engineering and soil mechanics professionals use the term void ratio<\/em>, e<\/em>, when describing the amount of void space in a soil or rock. The void ratio is the volume of voids divided by the volume of solids as shown in Equation 7.<\/p>\n\n\n\n
<\/td>\n\"\displaystyle e=\frac{V_V}{V_S}\"<\/td>\n(7)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

where:<\/p>\n\n\n\n\n\n
e<\/em><\/td>\n=<\/td>\nvoid ratio (dimensionless)<\/td>\n<\/tr>\n
V<\/em>V<\/em><\/small><\/sub><\/td>\n=<\/td>\nvolume of voids (L3<\/sup>)<\/td>\n<\/tr>\n
V<\/em>S<\/em><\/small><\/sub><\/td>\n=<\/td>\nvolume of solids (L3<\/sup>)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The void ratio, V<\/em>V<\/em><\/small><\/sub> \/ V<\/em>S<\/em><\/small><\/sub>, is always larger than the total porosity, V<\/em>V<\/em><\/small><\/sub> \/ V<\/em>T<\/em><\/small><\/sub>, because the value of V<\/em>S<\/em><\/small><\/sub> (the denominator of the void ratio) is always less than the total sample volume, V<\/em>T<\/em><\/small><\/sub>. Recognizing the total sample volume is equal to V<\/em>V<\/em><\/small><\/sub> + V<\/em>S<\/em><\/small><\/sub>, total porosity can be calculated from void ratio as shown in Equation 8.<\/p>\n\n\n\n
<\/td>\n\"\displaystyle n=\frac{e}{1+e}\"<\/td>\n(8)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Both porosity and void ratio are used to characterize the open space of soil, sediments and rocks. Groundwater professionals most commonly use total porosity or effective porosity to compare the open space of earth materials. They use effective porosity to determine the capacity of a material to store groundwater.<\/p>\n","protected":false},"author":1,"menu_order":4,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-154","chapter","type-chapter","status-publish","hentry"],"part":54,"_links":{"self":[{"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/pressbooks\/v2\/chapters\/154","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/wp\/v2\/users\/1"}],"version-history":[{"count":9,"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/pressbooks\/v2\/chapters\/154\/revisions"}],"predecessor-version":[{"id":683,"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/pressbooks\/v2\/chapters\/154\/revisions\/683"}],"part":[{"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/pressbooks\/v2\/parts\/54"}],"metadata":[{"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/pressbooks\/v2\/chapters\/154\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/wp\/v2\/media?parent=154"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/pressbooks\/v2\/chapter-type?post=154"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/wp\/v2\/contributor?post=154"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/books.gw-project.org\/hydrogeologic-properties-of-earth-materials-and-principles-of-groundwater-flow\/wp-json\/wp\/v2\/license?post=154"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}