HOW TO CALCULATE CALCULATE SAFE BEARING CAPACITY OF SOIL ON SITE? Suryakanta | Suryakanta | February 23, 2015 | Geotechnical Geotechnical,, How To, To, Soil Soil,, Soil Investiation | Investiation | 10 !o""ents
This si"#le an$ %uick &iel$ test will ive you a rouh i$ea o& bearin ca#acity ca#ac ity o& soil'
Procedure 1' ()cavate ()cavate a #it o& re%uire$ re%uire$ $e#th' $e#th' *#re&erab *#re&erably ly e%ual to to the $e#th $e#th o& &oun$ation+ &oun$ation+ 2' Take Take a soli$ soli$ ball or s%uare s%uare cube o& known known weiht weiht an$ $i"ension $i"ension'' 3' ro# the ball ball or s%uare s%uare cube several several ti"es, ti"es, &ro" &ro" a known known heiht on to to the botto" botto" sur&ace sur&ace o& e)cavate$ #it' -' !alculate !alculate the averae averae $e#th $e#th o& i"#ressio i"#ression n "a$e several several ti"es ti"es on the botto" botto" sur&ace sur&ace o& the e)cavate$ #it' .et /$ is the averae $e#th o& i"#ression'
Calculation !alculate the ulti"ate resistance o& soil * + usin the &or"ula iven below' R !" # $% & d
here, 4lti"ate resistance o& soil *in k+
$ verae $e#th o& i"#ression *in c"+ w eiht o& the soli$ ball or s%uare cube *in k+ h Heiht o& &all o& soli$ ball or cube *in c"+ I& / is the cross6sectional area o& the soli$ steel ball or cub e, then resistance o& soil #er unit area is calculate$ usin &ollowin &or"ula' esistance o& soil #er unit area *in k7c"2+ 7 Sa&e bearin ca#acity *in k7c"2+ 7 * 8 F'9'S+ here, F'9'S Factor o& sa&ety
Note' to Re(e()er 1' F'9'S varies &ro" 2 to 3 $e#en$in u#on the ty#e o& structure an$ site con$ition' 2' In or$er to et reliable test result, #er&or" this test on $i&&erent ty#es o& soil an$ then use your :u$"ent to reach at any conclusion' 3' Instea$ o& usin soli$ steel ball or s%uare cube, we can also use !; test #luner, or !one *use$ &or cone #enetration test+
Pre'u(*ti+e Bearin, Ca*acitThe table iven below shows the #resu"#tive bearin ca#acity values &or $i&&erent ty#es o& soils' This table will ui$e you to reach at any conclusion a&ter con$uctin the test' T-*e o. Soil & Roc/ ock So&t rock !oarse san$
Note' to Re(e()er
Sa.e & Allo"a)le Bearin, Ca*acit- !/,&c( 0% 32'-0 -'-0 -'-0 2'-5 -'-0 1'00 1'00 0'50
1' For non6cohesive soils the values shoul$ be re$uce$ by 50> i& the water table is above or near base o& &ootin' 2' These values shoul$ be use$ only &or #reli"inary $esin' The actual bearin ca#acity o& soil shoul$ be calculate$ as #er the stan$ar$ co$es' Al'o Read1 Ho" to Calculate Bearin, Ca*acit- o. Soil On Site U'in, N23alue Al'o Read1 Ho" to Calculate Bearin, Ca*acit- o. Soil Fro( Plate Load Te't
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Tas@;earin !a#acity, Fiel$ tests, Site Investiation
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A)out T$e Aut$or
Sur-a/anta
Geotechnical6
1' shiva" ya$av 9ctober 1-, 2015 e#ly how to &in$ &oun$ation o& house' an$ how can i select &oun$ation o& house'
2' Suresh 9ctober 1A, 2015 e#ly
Site is better &or &iel$ #ractical tests an$ knowl$e
3' Ciyi Folayan Cove"ber 2-, 2015 e#ly nee$s to know &or"ula &or $eter"inin soil #ressure un$er r'c rin bea"
-' Geore Cove"ber 25, 2015 e#ly hel# "e know how to select a oo$ an$ viable &oun$ation o& a storeye$ buil$in
5' yushvir ra: Cove"ber 2B, 2015 e#ly Su#er $u#er i$ea
A' k'anan$ January 2K, 201A e#ly #rocce$ure i"aes
K' 4"eLurike John chiene #ril 13, 201A e#ly
?lease I a" a buil$er an$ I want to be very in structural $esin an$ calculations' !an you hel#
' kasira: *srivilli#uttur ,ta"ilna$u+ #ril 1K, 201A e#ly
B'
10' Teena uust 31, 201A e#ly I woul$ like to know "ore about this article Sir can you hel# "e
Soil Bearin, Ca*acit- .ro( N2+alue' o. SPT .or 4e'i,n Pur*o'e' threa$50K61K2 Foru" Search FMs .inks <=?s artnkman (Structural) *9?+ 10
I $o not #ro&ess to be an e)#ert in this area, an$ I a" certainly not a eotechnical enineer, but I can say the &ollowin@ ny re&erence "aterial that ives bearin ca#acities base$ solely on S?T values an$ such broa$ soil $escri#tions is not worth the #a#er it is #rinte$ on' bearin ca#acity shoul$ only be calculate$ when the &ollowin in&or"ation is known, or can be reasonably esti"ate$ by a %uali&ie$ #erson@ 1' strati&ication o& soil above an$ below the #ro#ose$ &oun$ation' 2' soil classi&ication throuh lab testin or visual i$enti&ication by a %uali&ie$ in$ivi$ual' 3' $e#th o& roun$water' -' siLe an$ location *$e#th+ o& #ro#ose$ &oun$ation' Since you have S?T values, I will assu"e that there was a soil e)#loration #rora", so you shoul$ have the strati&ication *ho#e&ully to an a$e%u ate $e#th+, an$ the location o& the roun$water table *i& a##licable+' The ne)t ste# is to in$enti&y the strenth #ro#erties o& the soil*s+' The best o#tion is obviously to et the a##ro#riate lab tests o& the sa"#les that were retrieve$ $urin the S?T sa"#lin' I& this is not #ossible, &airly accurate #ro#erties can be &oun$ in a nu"ber o& te)ts *i'e' Geotechnical (nineerin Investiation
i$ivi$ual case, eotechnic stu$ies shul$ be carrie$ out on the strata be&ore $e&inin the ty#e o& &oun$ation that will be suitable, in so"e soils so"eti"es S?T is ivin an i$ea about the sti&&ness o& the soil an$ the scientists creat a relation between nos' o& blows an$ bearin ca#acit y but this value o& ;7! shoul$ not be taken into consi$eraton in $esin without takin the other &actors, that is not every thin about soil ' gc (Structural) 21 Jun 00 11@5B ou will &in$ several books which #rovi$e bearin ca#acity correlate$ to S?T values' These shoul$ be taken only as re&erences or Obase valuesO' I& a eotechnical enineer was hire$ to $o a soils investiation he shoul$ be able to #rovi$e you with this esti"ate' I& there was no eotechnical en' you coul$ hire one &or a no"inal #rice an$ have hi" #rovi$e you with an esti"ate base$ on e)istin $ata' Just out o& interest, i& you #rovi$e "e with the relevant $ata I coul$ see what I coul$ $o' * I have so"e eotech' e)#erience+ RUSSRASCAL (Structural) 2K Jun 00 13@51 94 C(( T9 !9CT!T G(9T(!H THT I TH( T(STICG 9F TH( S9I.' TH( C =.4(S ( G99 S 4.( 9F TH4<;, H9(=( S9<( S9I.S ( S(CSTI=( T9 <9IST4( !HCG(S C 9TH( S9I.S ( S(CSITI=( T9 ( <9.ICG' !4TI9C IS TH( T!H 9 Polecat (Structural) K Jul 00 23@3B I& itOs vertical bearin #ressure youOre lookin &or, then I woul$ aree with those res#on$ants who a##roach this conversion with caution, es#ecially when lon ter" settle"ent is a "a:or consi$eration' However, i& itOs lateral #assive #ressure you nee$ *such as lateral loa$s on $irect burie$ #o les+, then you "iht try these conversion esti"ates@ For san$, #hi anle 2K'5 C7-' Fro" #hi,o& course, you can et the ankine value' For clay, ! C7K'5 in ks&' In both cases, always consi$er the soil in a sub"ere$ con$ition &or a##lyin "ini"u" $ensity *well, "aybe not in riLona or west Te)asR+' n$ last but not least, run it by a %uali&ie$ eotech enineer an$ use a SF o& not less than 2'0' illia" For$ sesi"in$s#rin'co" S#iral (nineerin Services, Inc'
Geotechnical Engineering Investigation Manual, Hunt, Roy E. 1984 "rule of thum" estimates out there for allo!ale earing caacities