{"id":411,"date":"2025-02-26T03:25:55","date_gmt":"2025-02-26T03:25:55","guid":{"rendered":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/chapter\/5-8-bearing-capacity-from-cone-penetration-test-cpt-results\/"},"modified":"2026-03-16T14:05:35","modified_gmt":"2026-03-16T14:05:35","slug":"5-8-bearing-capacity-from-cone-penetration-test-cpt-results","status":"publish","type":"chapter","link":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/chapter\/5-8-bearing-capacity-from-cone-penetration-test-cpt-results\/","title":{"raw":"5.8 Bearing capacity from Cone Penetration Test (CPT) results","rendered":"5.8 Bearing capacity from Cone Penetration Test (CPT) results"},"content":{"raw":"Various empirical methods have been proposed in the literature to estimate the bearing capacity of shallow foundations directly from in situ<\/em> cone penetration tests. One of the more recent ones was proposed by Eslaamizaad and Robertson (1996), who recommend calculating the bearing capacity in terms of stress of footings on coarse-grained soils as:\n\n(5.54)<\/strong> [latex]{q_f} = {K_\\varphi }{q_{c,average}}[\/latex]\n\nwhere qc,average<\/sub><\/em> is the average cone resistance below the footing foundation level along a depth z <\/em>= B<\/em>. The shape conversion factor K<\/em>\u03c6<\/sub> (from cone resistance to footing bearing resistance) ranges between K<\/em>\u03c6<\/sub> = 0.16 to 0.30 depending on the ratio B<\/em>\/Df<\/sub><\/em> , the shape of the footing and sand density and is given in Figure 5.50<\/a>. However, given the uncertainties underlying this method it is recommended here to use Eq. 5.54 together with the lower bound value of the shape conversion factor K<\/em>\u03c6<\/sub> = 0.16.\n\nFor fine-grained soils under undrained loading conditions, Eslaamizaad and Robertson (1996) proposed to calculate the bearing capacity in terms of stress as:\n\n(5.55)<\/strong> [latex]{q_f} = {K_{Su}}{q_{c,average}} + \\gamma {D_f}[\/latex]\n\nwhere qc,average<\/sub><\/em> is again the average cone resistance over the influence depth defined above and K<\/em>Su<\/sub> ranges between K<\/em>Su<\/sub> = 0.30 to 0.60 depending on the ratio B<\/em>\/Df<\/sub><\/em>, the shape of the footing and OCR. It is proposed again to conservatively use Eq. 5.55 with the lower bound value K<\/em>Su<\/sub> = 0.30.\n\n[caption id=\"attachment_410\" align=\"aligncenter\" width=\"600\"]\"Graph Figure 5.50. Conversion factor for determining the bearing capacity from the CPT cone tip resistance (after Eslaamizaad and Robertson 1996).[\/caption]","rendered":"

Various empirical methods have been proposed in the literature to estimate the bearing capacity of shallow foundations directly from in situ<\/em> cone penetration tests. One of the more recent ones was proposed by Eslaamizaad and Robertson (1996), who recommend calculating the bearing capacity in terms of stress of footings on coarse-grained soils as:<\/p>\n

(5.54)<\/strong> [latex]{q_f} = {K_\\varphi }{q_{c,average}}[\/latex]<\/p>\n

For fine-grained soils under undrained loading conditions, Eslaamizaad and Robertson (1996) proposed to calculate the bearing capacity in terms of stress as:<\/p>\n

(5.55)<\/strong> [latex]{q_f} = {K_{Su}}{q_{c,average}} + \\gamma {D_f}[\/latex]<\/p>\n

where qc,average<\/sub><\/em> is again the average cone resistance over the influence depth defined above and K<\/em>Su<\/sub> ranges between K<\/em>Su<\/sub> = 0.30 to 0.60 depending on the ratio B<\/em>\/Df<\/sub><\/em>, the shape of the footing and OCR. It is proposed again to conservatively use Eq. 5.55 with the lower bound value K<\/em>Su<\/sub> = 0.30.<\/p>\n

\"Graph
Figure 5.50. Conversion factor for determining the bearing capacity from the CPT cone tip resistance (after Eslaamizaad and Robertson 1996).<\/figcaption><\/figure>\n","protected":false},"author":1,"menu_order":14,"template":"","meta":{"pb_show_title":"","pb_short_title":"5.8 Bearing capacity from Cone Penetration Test (CPT) results","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-411","chapter","type-chapter","status-publish","hentry"],"part":325,"_links":{"self":[{"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/pressbooks\/v2\/chapters\/411","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/wp\/v2\/users\/1"}],"version-history":[{"count":1,"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/pressbooks\/v2\/chapters\/411\/revisions"}],"predecessor-version":[{"id":412,"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/pressbooks\/v2\/chapters\/411\/revisions\/412"}],"part":[{"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/pressbooks\/v2\/parts\/325"}],"metadata":[{"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/pressbooks\/v2\/chapters\/411\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/wp\/v2\/media?parent=411"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/pressbooks\/v2\/chapter-type?post=411"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/wp\/v2\/contributor?post=411"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/libraryresources.nse.org.ng\/fundamentalsoffoundationengineering\/wp-json\/wp\/v2\/license?post=411"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}

where qc,average<\/sub><\/em> is the average cone resistance below the footing foundation level along a depth z <\/em>= B<\/em>. The shape conversion factor K<\/em>\u03c6<\/sub> (from cone resistance to footing bearing resistance) ranges between K<\/em>\u03c6<\/sub> = 0.16 to 0.30 depending on the ratio B<\/em>\/Df<\/sub><\/em> , the shape of the footing and sand density and is given in Figure 5.50<\/a>. However, given the uncertainties underlying this method it is recommended here to use Eq. 5.54 together with the lower bound value of the shape conversion factor K<\/em>\u03c6<\/sub> = 0.16.<\/p>\n