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An assessment of the geotechnical properties of the subsoil of parts of Federal

University of Technology, Minna, Gidan-Kwano Campus, for foundation
design and construction

Article · January 2008

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ir)LrIrlirl ol'sciencc. cilucittiott ittiti lcchiriil0gy .,\pril 2t)03
VolLnne I Nurlt;cr l iSSii I5vrr-977(r

An Assessrnent ol'The Geotecliuical ['rolrerties ol''I'he Subsoil of Parts ol'liederal

[Jnir,ersity ol"l'echnology N{inna, Gidan Krvano Canrpus, For Foundation Design antl
Constnrction.

S. A., Oke arrd A. N., Arnadi

Departnrent ol'Geology, l-ederirl University' ol-Technology, I\'linna, Niger State

Abstract
'l'lre sultsorl condilrons tll'prrts ol'ljedcral tJnivcrsity,ol"l'echuolog;,', N.linna pernruleut sitc ((iid;ui l(rviuttr
eur)l)us), nonhrvestem Nigcria rvas invcstigited by ercavulrng sir trial pits lrom the cxisting grountl lcvci ltr
lxtu'ecn (l()l) to l5) ure{ers.'hventy dtstr-rrbcd arid urrdrsturbctl s:urrples rvere collccted ancl sent tr) Jrrlrrrs
tlergcr Nigcria l)l .(l lirlxirittory. lvlinnit antl Natiorral Steel l{au, lvlateriai l:xpklratirxt Agcncy, liaduna lirr
reler,rnt gcotecluricril ar.ralysis. Prior lo thc excavalion. litlrological ancl structural ni.pping was underlirkcn to
rcveal thc l)rcsence ol'luiy geologic lcatures that nriglrt alicct the firundatiou ol'builtling u.u1 antrcipatcd
eonstructr()n ditlicultics.'lhe soil is hetcrogeucous Thc lrqrrid linrit rurges litxn 18.()()6 to 43.09',t, thu plastrt:
lirttit vru'res litlnr 13.8')t to 28 (t')/,. 'l'hc plasticity irriiex is erl'thc orclcr ol'2l'li' to 18.194,. 'lhe pll is neuiral.
sulpltlrte (S(\r') rurtl chIrride (t]l') contcrrts iire negligrblc 'lirc soil coliesion (()) ranges lioru l3() l(Ninrrto l(,4
l(Nrrtrr rvlrrle thc iinglc ol'intcrnrll liictirln (,1) is 80 'l'hc coellicrcnl of'consolitlution ((-i,,) uu'ics lirur l -17:rrrirr

c()llrl)cssr(ni inrlcx ((-'c) is ol'the orrlcr til'o 32 to Lt.38 lluscci on thr: llcltl autl lahu-ator-y rcsults, shlllou
liruntliitirirt (rcirtlirrur:d :trrp, prtd or rlli) curr lrc atkp(etl lirr lrghtly loarled structures. (ireater ltcaring uirlrirult)

ol'rilrorrt 33rrr tlclltii lutclrLrrctl on tlrc bcdrrrk is rcconrnrendcrl lirr tlre other arcirs.

Intrtltlrrction lo 9" 37'N and longitude

lrrtittrcle 9" 28' N
This u'ork lbcuses on the e\,'aluation of 6" )3'' E to 6" zolE (tigs l&2). lt consists
sonre releVant geotechnical clizu'acteristics o{'loiv lyrng terlains and fbrv gentle lirlls
o [' tlie subso il o I' pilrt o f F eder-al University,
'l'he southenr and ceutral
llarts ol' the site
ol- 1-echnology, N4lnna, Clidarr Ktt,ano are relatively'11at. The northern pari ol'thc
canrprrs u,ith a i,iew ol' Lrtilizing the data site is remarkable lor its rugged landscape
obtairled tbr recomnrending suitable and protirse outcrops The area is drained
lbundation types and appropriate lbunding by the seasonal Daggl river sy'stenr and
depths lor thc constnrctiolt o I uew associated lributu'ies (Works Department,
buildings Federal University ol- Technology N4innir,
I e84)
Sturll,,.\r'e;r Description
Tlte stttcl1, are;.t is locatetl alortg \,linrrll -
l(ataregi - Bidrr road ar)d lies betu,eeu

81
Jounrrl ol'science. erlucation rurtl lt:r-'irnokrgr, .,\pril l()oB
\loiurrtc I Nuntl-.er l ISSN l5()6-')71(r

',i
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,S 1i tl
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kF ti

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Itr!,1\ '\n.iti
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ii

' -. .. rr_ ar ,, .r
#-+ .lai .fu. .i I
r. r' rr. :i r- I
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i

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i, 'l
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;

..1 L' I i*r I

ffi .* t.r,-i,..

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l:il I (,tlrrrrlirutl (irolugicrll llrirp ol Niut'r'iu ,ilrorrilrg lltr krcaliolr rrl'llrt sltrLlr itrrir. \lirru:r
{Soru'r:c: l;.ltttzr'. I 995 )

General Geology ol'the Area coarse-gl'zrined granite and nrediunr to fine

The area irivestigated is part ol- tlre glained granite (fie 3)
north-westenr lrart of the Nigerian Trvo sets of joints rvere identilled
Basenrent Conrplex rvhiclr is composed of One set is trendirig N-S and the olher E-W
tlrlee lrthological Lurits- lnigmatite gnerss J'lre fonner are commor.r orl the northern
corlplex, low grade schist belts and the part while the later is fi'equent in tlre
older granite (Truswell and Cope, 1963, southern sector. N{inor laults were
Ajibade, 1e76) observed on some outcrop.
Lithological and structural
mapping revealed that the study area is Fig 4 illush'ates a typical strata log ol one
tunderlain by nronolithic granitic rock. The of the borehole drilled.
rock can be gloLrped into porphy'itrc to

88
Jottntiil ril' scicttee- etlLtcatiort trnd techlr()i()ta\ April 2t)t)l'(
Voluurc I NLulbcr 2 lSS|.1 I 59(r-977()

z
9o CN

(
6o rdiE @
LEGEND

SENIOR S
I
rr,^r rrr rocororr
SIUOEHIS'
H 0s r E t s
o f@|

lilJil elsr.r rr,.u*,o

as coilynaaTlalr s;!J:aE

&
Iu NI I-
lttt'
SaHooL af Eilcxrt€anrb
I ostral,ertc*urr.r,v
s

IERS fJil .ro".reo

U/ "uou

V,4 "ro"o.ro"r,ruo,o

UC

9CHOOI OT A'RN:UITURE I
I6FEULIUiAL ltCHtkfr 06.

fiC-] r;enroroeo
tl- I

CEXIRIT IDMII'T*AItr'J

sar SCH@l Of Arv,Rirm€rlIiL

sctrOat .rF SalEr.E rc ErJ.E

^
'E

u'ofdjff#i
SCAL E

6021'E

BIDA _ MINNA ROAD

Fig. 2 lllrrp ol'llarts ol' Federal University ol'Technology, Minna Per.ltranent site (Gidan
Ku,ano c:lmpus) showing trial pit locations.

N'l ellrodology ol' lnvestigation undisturbed soil sanrples \\ ere collected

I'he sub-soil condttions was liom the trial pits ilrd anall,zed in Julius
inr estigatecl b\ excaval.ing six trial pits Berger Nigeria PLC laboratory,- Minna and
(lig 2) honr the eristing ground level tcr National Sleel Rau, l\4alerial Exploratron
bctu een ( I 0- I 5) rneter according to Agencl' Kaduna lbr relevant geotechnical
llrilish stiurtliut-l eodc ol'plactice lbr sitc iulal),sis 'l-he laboratorl test \\ iis
rn\ estrgation ( I 9ti l) Disturbed iurd performed according to Britrsh standard

89
Jounral o [' scicnce. eclucation antl tcciurt;lo gy .'\1rrii 2()ttl'l
Volurne I Nutttbcr l ISSN 15()6-()77{}

methods ol- test lbr soils lbr civil soil paste starts to crunrble arrd carrrrot roll
engineering purl)oses (British Standiud lirrtlrer. The process was repeated uutil
lnstitLrtion, BS l-177: Part I - 9, 1990) longitudinal and transverse cracks appear
Dry sieve analinis i,vas caried out at a rolled diameter ol3 rnrn. lmrnediately,
in order to obtairi the particle size the nioistLrre conteril oI the clack thread
distribution of tlre soil sarnples and rvas was detemined. Consolidatiotr tests rvere
perlonrred rvitlr a set ol sieve sizes (19.00 performed on sorre selected undistulbed
mrn, 9.50 rnrn, 4.75 mm. 2.36 mrn, l.lB sanrples rvith an oedorneter to det€nnine
nrrn, 0.600 mm, 0 425 mm, 0.300 mm, llre compressibilitv characteristics ol- tlre
0.15 mm, 0.075 mrn) and meclratrical sieve materials. Triaxial sheal tests !\'ere
shaker. perlomred on some chosen saulples lo
LiqLrid limit rvas caried out rvith a estimate their in-situ shear strength
liquid limit device (Casag'ande cup). characteristics. TIre soil pH was
Plastic lirnit test 'uvas executed by kneading determined lvith the aid of'a pll rneter. 'flre
and rolling soil samples betu,een lingers concentration oI Cl-in the soil wAS
and thumb into aboul. 6 mm dianreter determined volumetricalll,
tlrread. Each thread was further rolled The level of SO+2- in the soii sanrples llas
betrveen lrngertips on zt clear flat glass evaluated rvith an ultraviolet
paste r.vith sulficient pressure to reduce the spectrophotometer.
dianreter into 3 rnm. At exactly 3 mm, the

LFGEND

m codtoo

mPotfrynrc

I mra;um ro

SCAt E rr'x
t-::t-
Ml00 0 100 r00

Fig. 3 Geological Map of parts of Federal University of Technologl,, N'Iinna Permanent

site (Gidrn Kwano cantpus).

90
Jtiirnral ol'scicrtcc. ctlttcatiort and tecllrrrltig\ Apnl 2U0ti
Voluuic I Nuntbcl 2 ISSN r 596-977()

Results Al&ough, the digging was undertakerr

Field 0bservations during the dry season The duralion ol
The soil profile of trial pit I is excavating trial pits l. 3, 5 and (; u,as
shou'n in ligs 5. The locations of the trial modelate ther eby indiciiting a urediunr
pits are summarized in Table l. The soil dense relative densitl, (Cla14on, et al..
prolile ol- the trial pits reveals theit the soil I995). Excavation r.vas terminated betneen
in the stud1, area is helerogeneous rvith the (1.00 - I 50) rneters belotv the existing
exceptions ol'trial pits 4 md 5 that have ground level r.r,hen the bedrock \\'as
sonre resemblance. Tlris suggests that the encounlered during tlre excavalion ol' tnal
soil around the stall' quarters (senior and pit 3. 5, rurcl (r or u,hen digging rvas
iunior) is similar The rate of excavating diffrcult as a result of the strength of the
trial pits 2 iurd 4 rvas \/erJ slo\\/ therebl, soil.
rridicaling il \'en/ stil'f clal' consistency'.

oEPrH ().rl t II H Ol_ O 6 Y

().o
. t --^,
:'i,',
"i,l
Loterilic topsoil
iilit l''i tt1"' lt c(oy 6rrd weotlrcrtcJ boscrncnt
7.t) ,.
weotlrgrod trosc,-lent
| 0.0 co rn1>etent t;ose rnc nt

t ,: sliglrt weotlrqrsd borement

I (r^ f)
l iliJi,
weo1hered tro5Crrrerrl
t 9.0
++ weothered f (roclured bosemerrt
+ + +
t+ t frocturq.c!,. {)eqmoti tes
jii
i

.,i

,f ,J

_.ii

,r.i l.i ..,.

;!, i i lit;'ii'..'. i':i'ii ii ili',i :\ ) irr ;iil; *t..;r'r:, rj;i i,r,t.i it;ii.i il;iii,

(l I
Jountal ol'science. ctlttcatiort and tecltnologv ;\pril 2(Xlt{
Volurnc I Nurnbcr 2 lssN I 596-9770

Fig. 4 Illustrates a Typical Strata Log of one ol'the Boreholes Drillerl.

,o 0.0m
o
x ox K Brou,n, laterite, silty , clayey, sandy, fine to medium gravel
o o
t' o.
x x x o
o
o
05m
Brown, laterite, silty, clayey, sandy, fine to rnedium gravel

l.0rn

Fig 5 . Soil profile of trial pit I

Table l. Trinl Pit Location

Trial Pit No Depth (m) Location
I 0-1.0 Proposed site for the university clinic
2 0- 1.0 Around the student's hostel
0- 1.5 Proposed site lor convocation square
4 0- 1.5 Around senior staff quarlers
-5 0- I0 Betu,een selior stalf ard.lunior stafl- quarters
6 o* I0 Ad.iacent to the School ol'Science and Scierrce Educatrorr
(SSSE). School of Agriculture and Agricultural Technologr
(sAAr)

Laboratory Results shrinkage potential of soil samples no. 5.

Sieve Analysis (t. 7 and l9 are ranked medium rvhile the
The resulls of the sieve anal),sis are renraining ones are of lorv shrinkage
sumnrarized in table 2. A lr'pical particle potenlials. The nrean value ol the liquid
size distribr,rtion cun,e is illr"rstrated in fig lrrnit. plastic linrit and plasticity inder is
6 Trvo t1,pes ol' cur\ies rvere identified. 271%- 20.7% and 7.}oh respectivelr,. The
Soil sarnples s,ith serial number 7. 8. 9. Iiquid limit ranges lronr I8.0% - 43.Ooh.
10. 12. I6. l7 and 20 have the ratio of szurd the plastic limit is of the order of 13.8% -
28.3% u,hjle the plzr-sticitv index varies
samples have the proportion of clar, + silt liorn 2 l'Yo - 18 l"l,
> sand > gravel Table 4 summariz-es the soil sarnple'
classification.
Atterberg Linrits
The results ol'the Atterberg limits Triaxial Test
are presented in table 3 Figs. 7 and 8 The result of quick undrainerl
illustrate a t_v-pical plasticitv chart obtained triaxial compression test is contained in
lrorl the study area. Generally. the soil table 3 and tl,pical graph of total stress
samples are of lorv plasticity as reflected in N4ohr's circles is illustrated in fig 9. The
trial pils 1.3.4.5. 6 and 2. sample no.l. cohesion (c) ranges fronr I 30KN/m2 to
The samples collected at (0.5 and 1.0) l64KN/nr2 rvhile the angle of internal
nreters are of intermediate plasticity. The lriction (O) was found to be 80.

92
Jountiil ol sctette c, e.lrturtttltl atitl lccliriirklg;' Altril 2()t)8
\,'olurttc I Nurttbcr l ISSN i596-977it

Consolidatiort 'l-est
Tlie results are presented in table 3
and a t'el)reselrlalive plot of thickress
against square root olr time obtained liorn
consolidation test is illustrated in tig. 10.
'l-he plot ol- void ratio against pressure is
exemplilied in tig. 11. The coefticient of
corrsolidation (C, ) varies fi'orn 1 47m2h7'
to 2.51m21y't'. The coelllcient ol volunre
ility (M ,) ranges fi"om
contpressib
0.2m2lMN to l. l5m2/MN and the
compression index (Cc) is of the order of
0.32 [o 0.38.

Chemical Anall'sis
The soil pH ranges fi'om 6.95 to 1.29
iridicating a neutral condition. I'he
conceul.ration ol'sulphate (SOa2' ) in the
soil sanrple vuries l}orn 0.0022ppm to
0.00l2ppnr rvhile the level of chloride (Cl-
) is of the order of 0.0078ppnr to
0 001 Tppnr Botlr the sulphate and chloride
corrcentratiou Jre below the nonnal
consentl'ation in uncontaminated soils
rvhen compared lvith greater London
council guidelines lbr classillcation ol-
contarninated sorl as cited by Curtin et al.
(1991). Excessive SO+2- content will have
aggressive ell-ect orr the cement used in
construcling tlre lbundation of the
building Too nruch chloride content could
lead to nrsting (corrosion) ol- the metallic
conrponent ol' the lbundation (Tomlinson,
t999)

(.)
I
-iounral o1'scicnce. education and tcchuologr' April 2(l()tl
Volunre I Nuntber l ISSN I 596-977(t

Table 2 Sieve Analvsis Result

S/No. Trial Sample Depth Sieve Analysis (7o Passing)

Pit No. (m) Sieve r 9.00 9.50 4.75 2.36 1.18 0.600 0.425 0.300 0.150 0.075
No. Size--
(mm)
11.1 0.0 100.00 91.2 90.02 85.26 80.94 74.40 69.8 0 61.9.6 46.68 40.06
212 0.5 100.00 94.36 59.46 29.00 24.62 23.04 22.36 2 i.58 20.1 0 19.16
313 1.0 10000 89 10 56 38 38.1 8 31 .48 28. 10 27.t2 25.62 23.12 21.90
421 0.0 100.00 100.00 100 00 99.80 98 86 94.92 91.50 85.1 2 68.8 8 60.04
522 0.5 100.00 100.00 98.84 97.06 92.20 84.70 80.12 '7
4.42 64.18 5 9.50
98.54 96.28 92.52 86.88 '78.32 68.48 64.02
ol.J 1.0 100.00 100.00 83.28
131 0.0 100.00 r 00.00 99.28 94.48 84.78 7 5.20 69.90 62.54 51.64 48.42
832 0.5 r0000 96.92 99.96 82.67 14.02 67.88 , 64.3 8 -5 9.5 0 49.10 43.62
933 1.0 I 00.00 r00.00 99.44 94.62 79.56 63.84 55.18 44 68 28.66 22.32
i0 3 4 i.5 100.00 91.92 96.3 0 91. 18 83.52 16.02 '7
t.48 65.3 0 52.96 44.56
11 4 1 0.0 100.00 100.00 100.00 99.7 4 98.56 91.90 83 16 12.22 49.7 6 39.46
1242 0.5 100.00 99.64 98.98 98.36 96.60 90.06 81.34 69.90 50.46 40.46
13 4 .3 1.0 10000 100 00 9.9 64 98.5 8 95.66 88.92 82.8 0 7s 40 63.5 8 56.82
1444 1.5 100.00 93.96 84.78 84.14 80.66 7 5.02 69.94 64.18 55 76 52.68
15 5 1 0.0 100.00 8 7.38 82.76 78.66 74.60 69.7 4 65.94 59.06 46.94 40.88
16 5 2 0.5 r0000 100.00 98.84 92.40 81.64 64.72 59 70 5 1.34 3 8.98 32.84
11 5 3 1.0 100.00 100 00 99 76 95.00 83.3 8 71.22 63.8 8 54.84 39.92 32.56
18 6 1 0.0 100.00 98.90 8 9.50 98.80 96.24 92.06 86.5 6 77.10 60.62 55.34
1962 05 100.00 100.00 99.94 99.32 97.48 93.40 89.40 83 62 74.22 7.12
2063 1.0 100.00 91 .84 16.82 63.82 53.66 45.06 40.32 35.30 77.90 23.64
ARITHMETIC MEAN 100.00 97.36 91.66 85.82 80.1 0 73.00 67.92 61.r0 49.13 43.42
RANGE .-
- 89 10- 5 6.30- 29.00- 24.62- 23.04- 22.36- 21.58- 20.10- 1.9. 16-
100.00 100.00 99 80 99.86 94.92 91 50 85 l2 '74.?2 7 0.12

94
r
i

.\pril
:

Jounral of' soicnce. cducation arrd lechnolor"i' 30()t3

Yolunrc I Numltr l ISSN 1-5e(r-977(r

Table 3 Summan' of Results of' Ltrboratory Analysis

S/No. Trial Sample Depth Atterberg Limit Triaxial Test Consolidation Test
Pit No. No. (m) LL PL PI SP cra C.. M., C.
KNim2 (Kpa) Mz/Yr *2/N,lN
t11 0.0 18 4 15.7 7.'/ Lou,
212 0.5 34.9 23.0 1i.9 Low
313 1.0 326 zz.) i 0.3 Low
421 0.0 22.9 18.9 4.0 Low
527 0.5 43.0 26s 16 5 Medium
623 1.0 4)) 24.1 i8 t Low 164 8 2.51 1.1) 0.32
731 0.0 28.3 23.9 AA
at Lon'
832 0.5 26.0 21.5 45 Low
933 1.0 26.4 22.9 31 Lorv
t0 3 4 1.5 25.0 21.1 39 Lou,
il4,I 0.0 19.0 I 3.8 5.2 Lou
1242 05 18.0 13.9 4.1 Low
t3 4 3 1.0 27.0 17.6 94 Lort' 130 8 1.41 4.20 0.38
14 4 4 1.5 1?n 18.2 d.d Low
15 -5 r 0.0 26.1 21.0 Lo'ulr
16 5 2 0.,5 304 ./-6.) 21 Lort'
11 5 3 1.0 24.2 21.5 )/ Lou,
18 6 1 0.0 230 17.3 5.1 Loia,
1962 0.5 35.0 23.5 ii.5 Medium
2063 1.0 24.6 19.7 4.9 Low
ARITHMETIC MEAN - 277 20.7 7.0 147 8 2.02 0.68 0.3-s
RANGE .. 18 0- 13.8- al
L.t- 130- 1.47- 0.2a- u.3 /-
43.0 28.3 18. r 164 2.57 1. l5 0.38

95
ioumal ol'science. educatiotl and iecllnolog1 April 3(){.t8
\illume I Nutrber l ISSN 1596-977()

Table 4 Soil Sample Identil'ication and Classif'ication

S/No Trial Pit Sample No Depth (m) Unified Soil British Soil Soil Description
No Classification Classification
1t 1 0.0 SC/ML CLG/ML Brown, gravelly, clayey, sill', fine to coarse sand.
21 2 05 GC/CL CLG Brown, lateritic, silty, clayey, sandy, fine to
medium gravel.
3 J 1.0 GC GCL Brown, lateritic, silty, clayey, sandy, fine to
medium gravel.
4 2 1 0.0 ML MLG Dark brown, sandy, clayey silt.
5 2 2 0.5 CL CIG Brown, gravelly, sandy, silty clay.
6 2 J 1.0 CL/GC CIG Brown, gravelly, szrndy, silt-v clay.
7 J 1 0.0 ML SCL/ML Brown, gravelly, clayey, silty sand.
8 J 2 0.5 SC/GC SCL/MLG Brown, gravelly, clayey, silry sand.
9 3 J 1.0 SC/GC SCL/MLG. Bro'uvr1, clayey, silry, gravelly, fine to coarse sand.
10 ) 4 1.5 SC/GC SCL/MLG Brown, clayey,silry-, gravelly. fine to coarse sand.
11 4 1 0.0 SC/SM SCL/ML Brown, clayey, silry, fine to coarse sand.
12 4 2 0.5 SC/SM/GC SCLiML Brown, gravelly, clayey, silty, fine to coarse sand.
i3 4 1.0 CLlGC SCL/MLG Brown, gravelly, sardy, silty clay.
14 4 4 1.5 CLlGC CLS/CL Reddish brown, gravelly, sandy, silry clay.
t5 5 I 0.0 CLlGC SCL/MLG Browrr., gravelly, clayey, silry sand.
i6 -5 2 0.5 SC/SM/CC SCL/ML Browr.r, gravelly, clayey', silry, fine to coarse sand
17 5 3 1.0 SC/SM/GC SCL/ML Brown, gravelly, clayey, silry, fine to coarse sand.
18 6 1 0.0 CLlGC SCL/ML Bro'uvrl, gravelly, sandy, clayey silt.
l9 6 2 0.5 CLlGC CLS/CL Browu, gravelly, sandy, silty clay.
20 6 -) 1.0 SC/SM/GC GCL/ML Brown, clayey, silty, gravelly, fine to coarse sand.

96
Journal olscience. cducalion and lcchrrologr, April 2t)t)it
Volurne I Nurnber 2 ISSN I 5t)(t-971o

FIG. 8 TYPICAL PLASTICITY CHART OBTAINED FROM TRIAI- PI'T 2

Normal Stress 55.6 il l.l 166.7

ltlt
ttlit I

Trial pit: 4 , sample No:3. Depth l.Onr

C=l30KN/m2 ;6 =go
400
--1
vz0 3 00
an
0)

7
l-
a 200
d I
(.)
100
a
\ I \
50 100 150
Normal stress (KN/m2)
FIG.9 TOT;\LSTRESSl\lOIItl'S(llRCl,ESOBI'AlNEl)tROI\IQt-rl('K.UNDRAINEt)'tRL{XI-TLCOIUPRESSIONTISI

99
Jounral oIscience. educalion arrd lechnologv April 2t){)tt
Volrrrrrc I Nrrrnbcr 2 ISSN l -596-9770

{T1""^}-
06
3-2

0rh

t3

3.t

E
sr4 3s
t/l
lr,
z
I
!lr 35
F
ga%

100%
31

Trlal Plt 4 Helghr of Sample 0.l9cn

Sarople No 3 CompressLon area l.lBM2
Deprh t.0n iv s I .4ln2l y"ar
FIG. l0 PLOT OF TIIICKNESS AGAINST SQTJARE ROOT OF TtDlE OBI'ArNEr) I'ROM CONSOt,TDAI]ON ]'ES r

100
-]orri r rul r) I )c l ar lc c. elltiL.rt iOll aiirl l'.:cl rttOiogl' .{pril 2001;
\i oluntc I Nurrrbcr' l tssN I 596 9110

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Discussion ciesign u,ith total settlement not exceeding

Fo undation llecourrnendation 25mnr and negligible differential settlernent
The fbundation artalysis is based on (1-omlinson, 1999) For foundatron u,idth
the lesults obtained frorn the fleld E'eater than 1.0 m or of about 4 0 m, an
investigation aurcl labot'atory tests using the allowable beating pressure of' 100 KN/rlr
regulations stipulated by Blitish standard shoulc'l be aclopted The total settlenrent
code of practice fol for"rndation (1986). expected will not exceed 25mm (Curtin, et
Shallorv (spread) F'ountlatiott al., 1997)
Shalloiv foundation can be considered for ln aleas covered by trial pits 2 and.4
lightly Ioaded structures for exanrple, lvhere clayey layer was encounterecl, the
bungalows and classrootn blocks. net ultimate bearing capacity, that is, tlie
Generally, reinfbrced sttip, pad or laft net loading intensity at which the ground
foundation can be adopted Foundation can fails in shear for a par-ticulat' tbundiitirrrt
be placed between 0 50 m and 1.0 nr below (Tomlinson, 1999) was calculated for stlip.
the existing ground level in areils covet'ed pad and raft foundation. The net ultinrate
by tlral nur-nber l, 3, 5 and 6 (fig 3) within bearing'capacity of 314 KN/m2 and 304
the clayey, silty, gravelly, fine to coarse KN/m2 r,vere estinrated. Apploxirtrately
sand. As a guicle in design, for- foundation 401'l' of tlie net ultin-rate bearing caplrcity
not exceeding I 0 nr in diarncter' (strip and \\i as ac'lopted ars the allowable bertrirrg
pact), un allou'ablc bear.ilrg pr-essLre ol . pl'essLll'e to nrinillize shearlng attcl
I50KN/rn2 should be utilizecl in fourtcltrtion settlernent effect. Thet'efore, an allowiible

t0l
 Joirnral of scieucc. cdttcalion ;rrrd tccirnolosv April 2008
Volurnc I Nurrrbcr 2 lssN I 596-9 710

bearing pressure of 125 KN/rn2 is advrsecl pressure of 10,000 KN/nr2 (British Standarci
for strip and pad of I.0 ni u,idth rvith total code of practice for foundation. l9B6)
settlernent uot exceeding 25 mll and Conclusion
negligible diflerential settlenrent l'he 'fhe knorvledge of the geotechnical
foundation shoulci be placed betrveen 0.5 nr characteristics of Federal LJniversity ol'
ancl 1.0 rn ltelou, tlre existing glound level 'I-echnology, M inna pelnlanent site as
and rvithin tlre gravelly. sandy, silty, clay. obtained fi'om geological field u,ork,
For raft foundation, an allorvable bearing excavation of trial pit, bclrehole dlilling log
pressure of 120 KN/nr2 should be adoptecl and laboratory analysrs of recovered soil
ri'ith rregligible total ancl diflerential sanrples have provided valuable data that
settlenrents can be used for designing and constructilrg
Areas covered by tnal pits 3, 5 ancl the foundation of future civil engineerine
(r (south eastenr irarl of the study area) structute.
'uvhere the rock level wAS encountered Ileferences
betrveen (1 0 - l.-5) meters, pad ot'strip can A.iibade, A. C. and \\/oakes, Nl., 1976, Protcr
crustal developrnent irr tlre Pan-Alrican Rcgirrc
ozciic
be founded on the bedrock to minirlize
otNigeria. Iu: C. A. Kogbc (Editbr) Gcology ol-
total differential settlement.
Nigeria. Published by Rock Vierv (Nigcria) Ltd.
Deep (Piled) Fourrdation pp -57 63.
If the ploposecl structure for British Standard Cotle ol' Prlclice lor
example, multi-stor"ey building rvill exert Foundations, 1986. BS 8004. Publishcd bv
pl'essLl'e rn excess of the recommended the British Standards Lrstitution. pp 4 I l0
Rritish Standard N{etlrods of Test for Soils tbr'
allorvable bear-ing plessures in areas Civil Engineering purposes. BS 1377: Plrt I
ccrvered by trial pits 1. 2. 4 and celrtt'al
- 9, 1990. Publislrcd by tlrc British Stirrrclirrrls
aclminrstration, deep foundation should be hrstitutiorr, pp 8 200
considerecl Generally, the t),pes of (la1.ton, C. R., I\{attlre*'s, Nl. (1. and Sirnorrs, N.
{bundation tirat ciur tre adopted at'e the E., 1995. Sitc irrvcstigatiorr Publislrcd br
Blackwell Scicncc Ltcl . Grcat Britairr. pp l- 59
driven or bor ed piles. n,lrich can be Curtin, W. G., Sharv, C., Plrkinson, G. l. .t
designed as f iction, end beiu'ing piles, or a Golding, J., 1997. Structural fourrdltion
cornbination of the two. Ple-cast pile, steel- desipgter's marrual Publishcd by Blackrvcll
casing piles Iilled rvith concrete or' Sciertce Ltd, U. K , pp | 300.
reinlorced cast in-situ piles of appropriate Elueze, A. A., 1995. Prospect lor sourcilrc stollc
polishing vcltures fronr rocks in tlrc Birscnrctrt
dirnension can be usecl Tlre climension ri,ill
Cotttplcx ol- Nigcria. lrr A .A Eiuczc rEtlit,,r r.
depencl on the proposed stt'ucture. Driven Jountal of N4irring and Geologv . \'ol -: I (lt.
piles slrould be avoidecl ciose to existing pp 13 11.
structLlres to prevent the buildings fi'om .linrolr, NL O., 1998. Six [urrctiorral borclrolcs
vibration, rvhiclr could lead to darnage. The drilled at Fcderal University ol Tcclrrroloqr
Minna pcnnallent sitc Unpublislrcd rcport. pp 6
pile should be anchored oir the bedrock at
14.
least 0 -5 rn beneath the rock level or''uvhele -I'onrlinson,
NI. J., 1999. Foturdatiorr clcsisrr lrrtl
piling rrg reaches its nraximurn driving constnrctiou. Pitrran prrblishirrg Ltcl, Sirrelpor c.
capacity ln {lg 4, the Il'esh basement pp 52 59.
(granite) \vas elrcor.ntteretl Lretu,een (3 I -34) & Cope, R. N., 1963. I'lrc Gcoloqy
Tntsrvell, .I. F.
oI parts of Nigcr and Zaria pror"incc Nortlrcrrr
nretels belorv the existing ground level Nigeria. Bulletin no 29 Publislrcd bl tlrc
(Jirnolr. 1998) Thelefbre . a pile founding Geological Survey olNigcria, 29pp
depth of 33nr is reconrmended. Fresh Works Department, Federal Universitr, OI
granite has plesumecl allolvable bear ing 'I'echnology, l\Iinna, .l981. Site irrvcsligirtiorr irt
penuancrlt sitc. Unprrblislrcd rcport. pp 297
300.

102

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