HomeMy WebLinkAbout02102004 BSC Agenda Item 4 -Technic:1i Papers Page 1 of 2
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4.0igii;414_'',=;Wiii:41.:'44MilitgatPikeR.41011,--:'AliNgt4,,,AROINAvAiteiaRtigtfaiNailii,14)1iPAttigiMMIXSMEtitatie7",
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ofk:f!:3, ftg ov,:ac-moo i rzL Nifrd o k bc n ,ft
etf.x.1.1, oess ff Mf). tfo
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Ueafi Lfl 1 3V0001::,77,:%ft':;M_07,"teld kA,11-4 lr4i-CS,fit'YTIO V4N.44 et", (4StiTria44)thatur4 SC%of tho:o tatoxfatkol fa.luz'as AIN Et
tity aid ria115:4 Oft drq116a f,.14af EgUey t1&34 iUJU by trees,;Ile cZt.ir,t;vrreald b bOJ1 etlortnot.47,
ihra Ttl botween;Lroo root growth and i,tridet
- - dab geWI:0 i ikc the 1.?"4 1) i4 it* WOTIci fiOtZ
9oncimly ba olas-isitiort 35 noodio-loal or brood IOW (dc
pUffiCttl cd tf145:pr 10 expts.:.=to trio athierse of- o-dunits) It*essential pa' ol a tree aro,ltte c .,ihe
k.-f,lkted T v.s L k i i uls,. 1 t*
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ffix.*.otaliK,3j IP*er, ,y :;:t-lt:17s-raniviai
tiv titciratts-n tiatte.i1 r.trika p4]-1,:wnAi iVi,`,421; t•61: ; ue 4,..Q fas-‘,kst g‘p-mr,1 part tit tre6: itAry
—14101'
aottgo, artd based on an akx-umatatIon 4iforrhaton watez ard transport it It kroi41 tho flunk to Ole Ioaves
farnatho Foundalion Perforroancra Corrritite: This pa. Ihrt fawn cf eap. The trunk pen...dint (ha ariqloitfing
par 011 tan prownled in t'c ri F;,n IntlowiN bacio Ii fh0f3iNii!111 LI-VAC-Val 1.N.)klaVilt;0411:f ff1,9 roots trid I ii
Vifib,40 p Sea ,
lotiotiatorl edtlo rnnl PITAPX4 by WO aIrir1k-0,90 up of the hoaidwood in;ha arnter, the cambium yet- tit
fer4rietatimi odip ho-aiirv.)cautiM by ii1 s.wriltinD,and frur. ho nutor edge Cif Mt trunk end the betk,wtii tiro
dabba mitirt.jelito pcili.vatit Roots grrxef teey as faV fi6
TVA
tivoen ttoti foufs ar$ 5eMie leatp:s Ttao ato energy horn leavoa 114,33
ct;4313;e3;Of
ki 4 or,dtons alorg.On proposed correct- noassti ot OfattatOil water frorn1tie tovaoi
Mik:Oif'=1:= 4r
' tiqq.nii-1;147;irn,S::A.ft b du- 1 Examples wilt be, tire- teroo0 their trunk in the form o ztP. Wit-on lb s.aP
nted: roaches a 103:4., OE) Wfdar rtvapcito into MO air The
nap lIhrel$mineral gaits horn the eaith to Ihe teaver, If
SOIL MECHANICS A$AFFECTED SY TREES thloropt411 in the leavog ant&Mt; tinuihtlo convort bi
mttlt into food through photoeinthesis. Mit food then
404fis balk the aeo syelom thic,41 paths juct bek.rw
the ba-i:. is triis systg-tat b,,t,,;Cb makes a tee
kl; e 2,Ye,
torq oi consieltrtiff .;tio a beneM fa rtma-
,-.24-4W4T-
kind, IfiX,o,-7 tinVe been tl‘Mtlen ;35:-many as 4(40 fr enhaering teems,we ate primaniy botIcemed with tho
yews r.Ajo.vI Does absotb I ii' tranSpedate,pro, 1);ifir i rcpo- ori ci I)io wattdrawai of inc.,:stur
vido aorti ;yid 101,10m k:;arif radiat.ion They nnharion from the roil end its eventual L InscAgatitart into the atirxi-
';:a,.
air ponicalton,ad in:IV c of erot;on and cool. a sithete, Atli rnp%have Wen inall:01()gland ty:0:4.fr.:30i;
$4,7titP- 774--qiW7'2,;14 kroitt:gi dizgp:43., IN nj# rot:Pict-on tora:if, howovra,the fe."2,24fE haw,:not*ways bow)uoiforo*
polhaps the:4.rr t.x.net,t at.ii..Y:y miii,,Anj thfi ert;;I,NWit4tit aFpx-oigt px.-47majraiti ,
efi1laliC0 stioc,Lirxtaag t4rKisc4ie. Goo htc 1.1 tb abiI,Zy to accutetoty ITotylrAlt6.: utij
can apprudzeto be tiewty ot oh ico btatichog rroisturo tossiroplaciitmon[sal be Sx-fil untie,
pcoe 0.4;in umbriatla for many ot rho ocidr n be 01 South Dri..!...nollo°1proFenteil 3 Tonkin!)of tce.es in telme of ttto
whoge rcutgiijro rihnoce hi ti be Pacific danice potential.A riolred copy of this tanitia9 is con-
Co riA it4:110E1 ri Tribe 1.0'1
Ireeg r5o havott..iel dowins4liti Thel,r I-4.rkt;telt 41:p.:.thnq tn ttAn(..peate: Ht.mr-stan wee, we do noi haie en ablm-
Porvett rind Kr:,:pte In the GO haeo peen dame.v.t Pell4rir trees;ilaWOW we*a may be mow
iniured or tollixi by falloyl tree-s. Trrt fIX.t1,&cfocj,Scis Oa*u*.--":.17:or-ii:ot ciciy artirc i. i,xxitimintxt iff ItT3s
ad bfazk rifk Tcoo S car:rt1O0 t)3ziti CIZOII:f:, merit to fi,ax,3rnplf5 of U.::,1O0.00l mosture oii bef Liact3.
oaniont of the art,damage 61x-if oci p<rafir 111-40!7i, rind which 4s alovort ith Fijurci t O ink-west is tho
4'4mo wiTh UHF reception. PO haps be flq):111,1 f.Z`S1 cf talico cl ibtee porrtwtant misivre deficiomy
tree.s lie in thee(tonne 10,10E6df.gatil foundn!liurs In 1 i73. rx,moupl wati futher 13):P1Ored toy Hx_idliero who mopt-;3„irod
iorwt$.and Hat.0-1 estirnelad the eprita criof ryt expen• the mi a-I:attire content tO the cioF*ptairnity of vate-)ti
oac 1,61.3.1.in the US In be 2? iiiic tinaet 9. in 19,ft';', kmkti,5 of I:Net; c-14 woe cfratwrg in a variety c-1.1 0,4
Powrioy.f3,Hwys:F7,5 e iciaIel Co orgt oipaor ri-ac os t4,cif which worn in Ciiipltd Aix-rained riatatiltroa
PasIdotIltA krAeld-Ttlions in the(jct.,:ii I kii.r.10n,titAtKi 10(fig...tii7Vriptistivo for g Poctrir ties wth.kin;;.,
2
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'technical Papers Page 2 of 3
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Tabb,,t. R.:,sk of damage by different vartetie of tree
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1 Rankeig 1 ri436filfftti I MaxitYliA tialgrit ok I e_parabian oetweon 1 minenum reKx.Nr argil
/i il Hawthorn 1,1 itiod , l-c).ii‘eiiria_.s itt 7titwt a kr1 tfteldirit.ffilvr_rti :._'-,,,;,,$„...it.4..,
I 7 %Cf -ZSerili;ttlefiq'eA
I 3 1 eiiai ill
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r 18
t_2_1_ I Pupter 1 24 1 GI $ . -
Coma=Ash 1 23
7
25-30 [ 7,5 I 05H ._,.....,
i 6 1 Wilco 1 15 t 1 1 1H
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/ 7 I Efrri 1 20:-25 _ 1 12 I 0.51i _
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f;47 p i 1-Wc.T w e--7 1 rn o 17-24 1
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LILL cyccals ..,_ if;t6._____...a.i......________LO.%ti
d'-i-1-'t't.P 1-N-4.1- • .1%!,%.4.' ir:'.r.,r,',„
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; -I_ 1 i P■ey. ..._,_,..„.>71;ip
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TT 00 44 .0 i.0 kid /0 40
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ElivAsiNgat+2m...a 040 r...-.7kierdra RaspoRP flr PR
Figure t tesisonat'orietion in rekotVure comemi with end with= Figural_ An exernpte of euii Nikuktura anti rg
curn.ziiifor p3pua .7 is=el z.bad
..cergirmi,Efiglariel
in a Raider Clay (P1 --,.. 29%) it 6illlt in Figure 2- The
tri)tzlture de5cit curves ale calculated by multiplying Ihe bites dam to buildings,assuming#t4e t
change in moisture conlent tiy the appropriate layer thick- he cure s are mnsidered. They aim)
ness, in reviewing this curve, it is significant that A does folly of simply removing eAisting trees ir
represent the most severe condition for a tree which has for the construction of a new residential
been judged to be of a lesser threat to would he an
Ctak free growing lit a soil whose Plasticity Index is less WHAT Ciiit.1$., 5 E.X.1.7.'89$P* ,011__S 1
than sumo of the major areas in the greater Houston, SV/it Lt.
Texas area, The availability of such data in'England has
had atignificaril impacts on the construction, business: As clay panicles are formed, there Siff
Whereas it was considered to be epracbrai to plant any points in the perlicia errangertwiti'Aber see closer to a ftlitJrNigtiOrt than[is ultimata height,those triUal itebalar$041; the
data do provide some bases for the pianiirg of oeriairt whenever.Vtiltrng''of uiay particles its'Or<
3
(...:Uck nee to continue
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"lechnical Papers Page 2 of 3
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11ke result is a claY patlicie tYpically has a heplive neoative pressure (expressed as a pce
net electrical charue on its surface. Sjice nature likes all rive to ambient atmospheric prey biro
things to be balanced, whenever a water frolecu•e drifts which Whit on Identical in wmposition
otose enough to the surface of a day particle,the nega- must be miliected in order to be in equi.
6vely chacod Urfe ot theolay particle caoses the,m;i- porous,pefmeable wall with eoit warier:
live end of the water molecule to turn toward the parlic:e lent to permeable waif with the soil wal
If it is.close enough to the particle, the water molecule is equivalent to that rmasured by test met
attracted to the Clay particle surface arfrIciently _strongly D3152.
that the water molecule becomes trapped. Aso, unal-
tachod or 'free' positively charged panicles; caved 'Cat- The osmotic suction is the negative pre
ions',tend to acquire a spherical-shaped arrangement of pool of pure water must be subjected
water(1101EICUIeS whIch have their negative ends direct equitibriurn through a semi-permeable
toward the positively charged cation (and their positive pool aorigaining a wiution idenricad in
ends directed away from the cation). When the free cal- sci water;decrease in relative humidity
ion is'captured', water molecules approach a day par- are of dissolved its in pore-water.
tide. The attraction between rite negatively charged clay
particle surface and the positively charged 4:.tuiside of the FOUNDATIONS AND (RIZ
iiiori Whetu(if Wald nok -ute aum the ualo .to L.,,e
"oaptured°by the clay particle,thus in-creasing the amount Many lightly loaded foundations are di
of watoi asseoialed Lkie clay particle% strucied 'Ibe.basis of economics, risk
dation shape and structural loading_
Clay 61-ti are very small, A typical Itaclingto partclo economic considerations, ttigher
night have a tot,' jrfscc rea,(1c,p, 17-ttonr end edges) foundation design. Most of the time,at?
of apprexhat.aly 1 10-5 10-10 fi!, or retotedbyLheowcer/bui!derstr ,
0.0000000001 f!) areas gn, this is very emalt. Thai v-onle 'revels of rick are a.s,rvzi*.d
57.,rnnctite palfirles, h:Ive a clirrtottstr that is lon to 1,000 founr.13tion and thare is nil stern thing a!
titre sneer than knalinite aqlicies nriel thidtnns-sit.at d Om. 419 o1 these fou,riattors must
tri try 41D0 times thinner than kaniihitell4 and; mnse- areas where PxpAnnivil soils are preser
nuenny, typically have a larger surface area per panicle, been removed prior to CNIStrUCtieta. The
Thus, a simile pound of rnontrrnrillonite particles would typically used in the area with increas
have an irmrerible total-surface area efapproximately 800 and decreasina levels of cost are discu
acres F25 hectares)11')with which to attract water.
The above recommendations, with re
Thus,expansive soils are very small in size and have a foundation types and risks, are Yety g(
large surface area that attracts free water. Because of type of foundation may vary as a furac
thew charwleristir--s, it is new to see why it is said that loading and Mil types. For example, i
expansive soils are those days that exhibit an extreme (baling slab foend.etion may perform be
change in volume. footing type foundation,
suction is a measure of free energy of the pore-water FOUNDATION PROBLEMS CAUS
or tension stress exerted on the pore-water by soil ma-
trix. Soil suoton is, in practicat terms, a mezolure of the FOUNDATION.SETTLEMENT PRODI
affinity of the soils to retain water and can provide infor- SHRINKAGE
nation on soil parameters that are influenced by soil wa-
ter;e.g.,volume Mange,dafehmetton,and strength Char- Several authors as far back as 1950 h
aotoristics
or soil. The mil suction is measured using the this type el clistiess_0.141 Buckle/Pl. pro
5iter paper method in accordance vvith ASTM be placed no Wiser to a tOSiderilia'r tOt
uipmate height_ The basis for this rec.
Tiu i divided into two components., Matti wntained in Figure 3. it was not, hooey
eiion ad uwitotic wiltion.. The Ini9ifix k the nized by the designers and WeSb-uCiere
ciicK ht7...,re to continue
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Fcclinicai Papers
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abteni. ,.•_.._,_ _
-T',,,--7,•,-ri-i.4,7,...F1.-727;i-,'..71.!.1.71c:77;;:.:IiTrii;: rii;
1 i;trtrliri4 S4.iiAth.Piars
1 retradabea win a travel wee) citinfi.kier to lie a rnini
1 ,
1 fo_lridiibon A mink-mon Q14,44 vace of six- 1,70.,:es or lag
I 1 rartukal UGIN tNS trAgidat,Ott Ow gials at&and in
kA Am,:t.r .pitorto. x.riarltda.&goal 2,-e prrlt en
1 I 1 hes Page been parievixl pliw tsi Daratnxioti. Tr*cina,
1 brigs must be pliveci bekes the potenlni active Zone 1
I frilriline i.eritai crilled ibenn9 i#leaval ckiie is evens
I ; La il:k diati's Atz-ii ncirrapamli,,e7..-4.-,4 xa pms=1„.„,-,-,.,4
! h-Forinri can '/F.7.,kye-F-i i.nt.Oti Of Of'zili?,1 f011r,
i -------------- '' ------..-----t----7—e--- — ---7-_----.4_-----
This irmiclelon sy4-,isiri IS.,kist)Sill5d for the u-ea-awe
1 :iiiab-Orr-Fiii Fatinr±,iiitp Ziumorieti Qii Piti-s
I Saik gierires.mt. This system has=no risks with Pave
1 1 tundslion tisli-e4,1 arid rrk10Arnants,ikiere expansive m
1 1 xeserri. However if p..-,sidwe Ctaifia9a and votoi.ak,ri CI
1 I Prttl,gli7;4;. tt rairAlli51.1.11%.selcipwfv-_ni s_?..listv...,!
Ili thiciote.4 is etratotad such that once it ia.cankinatt e
1 1 1 bat aintliiuns fposithie drairive,vegetation..--art-ol the i
1 vertical rise vviii t.,e minimum. The-5-ArtactuiT4 loads cln al
luywA,4 eliT.16r6.11i6'4•041z5 01,a Fie.I
IFipatng tf-`,.-■liftened)Slab StvparLod on PkYs. The Slab can 1 Tim t WI Di&lye tit v.h.,/flAki41.16 VbF,E,A'CZ'I L.Fb ic-Fautig
1 eliM&I IkTfOeflaCIlaiipRecinliwi,e4 oa P%i-TealkAeti, i Ft Ft F.,bv.V....2,17:!,1- ;,,,,fr-.,Nkii with prisiiive 4.0„il.:s..-_,p,aro wi,
0 contra Due in presence of piers,the slab i---.ati move up
I / enconsive snits are present bland down. In this case,
I i kin.the drilled piers should net be doweled into the Tar
1 PrINI$jV8 gf*are_egi.nrei„.g!rii,
- .
,i,r,- 4,i, - . . The risk on this type of intindaticEni etbcod sig7i
__ray9,,Anoakiti.damiromfkl rtr PgRt-
[ Tentierw simj i 5 built and maintained With p0,1iinta d'atherge and vegeb
I I Wit`ti. MI pieta are used in this type a found:10er' kir
' Lii-'----&13.tairtigazi ir;11-,,,,3tnte a Texts ztr.L,,,,—
44'kiiaariatirin and are pivirrinini,3.sebstectrity in the at
Itees have been remove:10a ii construction and%Iles
f exprisioseys exist these foundaWns must be signiiie
Ist&lied to marinade the pvientiai diFieterilial,ireiti
L
,-----L-2----- - -----:-------- -----
WrTgg built on concrete stab-on-ground foundations in - -
the-IC.60 time period. In Houston,loxes,as an exampte,
f — ------:,•,
the post World War It buitding boom incanted upwards ot
I
100000 Piom oonstucted in the Souttri*st pad of The i r • \ . ,L,i,e.4.:4_,.....i7d::;:-'''',• -. _
City, whore the &oils were typicalty very expansive. in i " T f„ ,
most oases, thew hone s were iniliaily oonstructed in r . A.
Subdivisitnis outside or the City knits, but were later an-
.
vexed by the Cho/ Thus,no building codes were appiiem
._,.ince tn..
bts rear esisie was largely farm lend viihial was
-2,---______,_______
barieri of"twos,One oi eva things;hal wee done by 6.-idi-
vidual hortreawfiets (and everi scoria suitdiviz4cin davel- • -
•
bperb.)was to p;ant trees in the yard close to the bunda-
c O' k Chi ,,__4 R . 4,.. L +__ 4 -a,kr. Lh as
..: I. ..!_.7.
V1/4:.,....,,,,,, -..,....- ...,...''.,'.... 1...As. 4_.{}-,.. 01,.. .1-F... n. i WOW,
04,10(48 I.Pat,:air:/.0 U tc,7 1",s4'57 I!,....41. i.w I 15.A t .au bal',al* Vd1 r
i......,..,4 itfo thrx:r 1:„.,,.3.rio..4 of mzior girc.A.th, their water cto. Fillurfil), A curve kil l'eaurAglien VOffiCAl ill-CYCITtelli I
tzeighl
mart;t-alcafiN ir.=ad z..-1,1, fmtnr.fotion probfrnw t,,,x)-.
gim,
--il is ticr,:ir-nturi at ii-t_l tirr,A-PI r,x1p.E.Jrtmtion
=Atilt r.q.i.) e t",.,1-5ril the c14,.nt,,74 of th2.-01h &rd
SI:p;die dim h.,,, ,e, tht that whAn n slAb is if:Paekvi ryn iligh.t 4111....ko cad ihp align; TrAgt.:1 tc;p wig.rot,Aqta on
47,r1lumr_i, pp..r,r9Pion _of soi! moisture i,s refaMed, tr the 11 ..ofnfti,, dijilivi wet pRrinds miffirient mitap
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I'e.cii ni cal Papers
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rijr,ii, kt N.AitAhl..$ far tle-ii growih and 3oil moisture eon- Figure 4 shows an example of a borne locutr
tents may not be substantially affected by vegetation, Southwest part of Houston,TE.1X86%4PAase slab-ct
During dry summer months,%ten eveMrration rates are foundation was uriderpinned using drilled pier
hick the toes will oblaan larqe CrlalitififIS of moisture from the 198.9 to 1990 drouohl, the foundation incur
alrealy drY wits,. If thew trees ate located in close prog- kInal deflections. At our suggestion, a root ban
trerly to liqtilly-lualod structures such es houses, their birved with an automatically actuated 5oaker Sy
root systern will move toward the SirlICILlieS,in an attempt applied,and the foundation not only stabilized,
to End a moisture stipp;y. if trees are too close to a house, rebound warned. The example contained in F
desiccation of the soils bolow the Flab may occur,caus- not, unfortunately, an isolated exempts. Sett(
log settlement of the slab have been obtained in the recent past using pre:
merited plies and heiicai piers.c41 Vert:ice;misi
ere nave enjoyed a very iirriiied use.
r-----r—ri
,ax-nrc4. Arrnt r#,X
0£4,4-AWICP4 tiltP4...4 X ilht-7
1.1'hi, 4\a FOUND-A-1'10'N EDGE HEWING CALI3ED El
1---1 ! 1 \ i , .,„„ i Is.tr,
OVVP, I: k,..J1
1 1 r---i '
f ( \I
co.....,.. .e-=....-..... 1
To ci,,171-1pensate tor the salitormnt of that cutor
\
foundation due to the extraction of r,-..4:".isfarro fre
,.,,,,„,,....,,,,,,..,,,...../,,-..P,,s.0,1r ht a h-cal ,11,
41 it Li 1.:-&I I the 1 W 1,,,,,SQ V.,,-,...,-I a*k>,.,'',A•, ...,......,...t.,...-.
tive;1-1=u:a was to ptace Inc!four:A=160n on fel
i ,„,-,------_,_-_—..-'--,„, '------„, ,,,,,1\ 1
- pierfl Most recently now..v.r, a MItlitic41 ha$
l'''' / '----'14,-,.''''..-''"s---,:':-'''.- '''''''':\''''' 1
1 / , -,,1
,;------2-'''',----"''''',,,NN,N where the plarq becArne P rielliri1450t, In Ole in
the city of Hnietton. Texas, there are Rubctivfi
L.1, -1._ ) g.....--1,—.1 -N..,_ \ i
.... 7.., \J ccopArAtively email building lots which often
tr"-----`-'\„„
,-.-7nalt, older homes, became very desrrnble h
),-, their location. in many cages. the foto centagi
0 ) I 0 3 prolific trees,which were removed to make w
i ,,,i 1 5-i construction of larger homes. In many such ca
log was done to COrmpensale for the inevitable i
the soils which would occur when the tree, 1
0.iwi.::.:Aiii..fir-TiI=,'■;I:r. r7771
ailkflialtratE:Irr F h i
desiccated the soil in its near vicinity idas gen
suction forces moved sail water into the desiii
• 1 , Iii \ 1
1 \I eas. It does not take much imagination to ir
mood of a homeowner who, in many cases,
I ,,
1 / I trioneys to have a sturdy foundation t-,onsitruci
1 1.. / i have it begin to move soon after the owner no
I ( 1 example of such a condition is shown in t'igu
I\ ''.41''',-,, i foundation,in this example,was founded on 1C
drilled piers,which had 42-inch diameter be.iiis
inspected during construction, The pier shat4
A to the otincrete perimeter beam The soils had
index in the 611%rerige_ A Pecan tree was le
log the construction pro5",ess,or shortly'choreal
,,
I L
Z, ? e'T,
of foundation induced damage boadrfai.iWilif6;
t 7 the iirsi year of oonsbootion and ;10'11'8, in tk
worsened sieeidily, A iiteiatiiiii seariit failk r"
„....„,....-.
-- 1. $1 .‘ ,,,,' ;
-,..-
iuty Litxuaieniedciiiicin a thI3 phzfzvr-v.s.nc
p.l.g■se,.4, Ail arANtrarnple?,,r24 tai!ky:5-...:1 al till:410.30'cm zaa a osult et
in tiii) LlZ16 of Teg23, big: ',31 tiVa tititCd State
Oro dgptetiuri Vt owl:Shiro at 1.11-1,..,dges becaiuu et trees.
_-..h ciriXIIZSions wt-ro,however,fotind in!Her
M6asureintrirts ware laken afler 9,1t4 installation and:41'1er root
bankoingaItation CAASIda at the United Sttiler . A ticting,F such
6
is,..;:ioic here to con tii-iLie,
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- Technical Papers
Page 2 of 3
• 41110
--,1_, WrilliiMd ifIr 11.10 Bibliography.Seclion of tiliti.p„--:.ipr-, This
,.:"•.,:i,,--
&tgnificance of the Yee rernovA sikraSen is perhaps boto
i oust:rated in Figure 43ftrt, ln thks case the renKoval of
i
it!Phr) l.:iftf3r(eieoz5:3,1.10 0:,461&.iir6pti,3-iario:103:foifirnehea:virii)Aid-iicit-1 was
il I 1
i
-.1 1 Li i i
..'s 1
\ ,e- --,,.. ------- -I
I it.___i i ,,. 1.
i- . r. 1 Hi 1 I , ,}
, __ i k
j 1
i i 41
1 r— 11111 1 ;
N. .,_:ill I
1 ( . . ne
i . 4,......„.
I I I
- --1
, ''‘,...„--- •. 4
"I r _ : i;A,....,
i 1= i 0 1
L—N : ...,. p-1---
I i ' -.:7_111.---_..1_,i..
I \ „ r 1
I 6
1 I 1 ..L.,,, 44■•01.1.i L.,.4.,.., i
1 i
.3, ..---•_._,_
;.- T -------
„.._
! .1 -„, 0.--• •-* Mill 1 / 1 1
-''
,C*
pil,:_77,--:.—,.,------7.---...=. •,,,,:\ :..,----.-,i-i,,,, \ 1:
..,-• ;:--- .:77::- :,-- ...._...':-..t.,'..-. -A.. -
...._
-
__,
.t,,,,...„„ '-:.•,:...,„, .., . 1 oo"'"'. .t
4. .
t. _ 0.
it<i*,4440 Si 7= )¼ ''', \14\°41t. iii
I
5 M
Figure eorop f to o a horna which lull tmn 4doe;Wsly ' -"- ',.., -: ---. (
r--- -•,'-
ettiod 4 the forricovat of 4a_Pec.ao trii,e,
A.....,:-
- ...A...A m-.4"?.$..14,7, ......g....44'Om., -,
tt- .D 32-:1.,,4.,,,1-.-._''''-*?- 4 Figwo 7. An exam,*cqf a hOtTlt IA Houston,rea.)as,wtilr,:n had
bin coostrmtotl on a roadway that was ifood with Post OA
A4g.i 1
trees
* i
7`..._,.....,..;::-''-1,-.,:g 1
:A i F ispre 7 shows how a re sfdentLat t.,3'..tilding was c,Lied nr
t i i iv
1.1 the edge of a roadway, which, before the tirne':of con
-i l'il
'' l -,k k- ''I
I'l 't. 7' ------------------C1 i
I slrudion,had post ook tieer3 on either side. The removil
or the trees caused significant heaving of the foundatior
.- At tho roar of this,and F.overal other buRdirigs,16-hich w9er f
ti .,."
/
I aristructOd along this roadway We have boon able ti
„,
_ .
„ . ...
lit/
treasure heaving in a limited Eflifitef of caws and tart
results are contained in Figure a In compering our Oat
with That shown in Figure 9,we can see RIM the slope o
ci . r___ ,,
rtl•sri,-. ._.':,'':-Ti•.-.,zrz..w-:'-'iir----F.:. _"_:---,ifi----? our data is sleeper,even though me of the curves eeerr.AN
a......fLiLLJI,Lit____1141.4
to Wel out after 7 year .
;.i"" .)17,7, 1„C-,..1_.11:71.„_____:!,i
---a
As.rnentionod earlier,tree roots tend to desiccate the wils
•
In the e,w0,that the tree has boon removed prior to hu.Ad
ftuto fi. A copy of a Vtilleag mow-tent thM occurmt 4s a ing construction,during the useful tife of the funicrure n
matto a tho removal of a Poplar flee in LA:-)nr.fOrt,EnVlaml if a tree dies, subsoil f3welling can°ma in the expansivi
7
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•
1 , -Techn icat Papers Page 2 of 3
• •
b) i he pier depth Ottaki bfl C.,-,..4.1d)that it could re the,
------ xocca rt-Aat•VIJI V,...TEA,ik keA t
Ioadli due'to expansive sods tia.t eixtend afrlr,-a
the shall porinikifor.
f V I
/ ---- .,--___ i c) Mote extenive soil tests iiiio Fregkrice-d_ Soil b,orings
i 1 ,„:_,...,,- _„..„„.4.7:
i ,,,,-- .._, ---,,,,, near a tree roust be, as a minimum, 25 to 30 toot
P -.^'''' -,"
deep. The.,doplh to Mkt Veit-rod the IS exist rriuct
f ..fi,e/ ...---.
12 ,,,,-/- i be determined since they are a basis of dont:4mq
f e } /-,' ,,--- J
I , ...;?„..-' l the depth of wnstfant soil siction. Potenbat Wrtinal
1 rent values shou:d afso be oaiculawd..
, 4 4 4 4 i 4. 4
1 4-4-44444,40.4. f In the &vont that a floating: stab foundation is weed, we
1--,---- - -- • ;----'•''--- a- - -------I reosmimend the stab be stiffened to resist the subsoil
Figao B. inOvenVAtS dila 10 the presence of tree , in adctifion,the
ea thin the tr4.--lo root zone may have to be offeroicatiy
stabili10 le reduce the potential inovernfots.AkIriatively,
..,.--
I t 1 Id 7 the site should be left alone for Several years 80 that the
41--------- --- moisture f fTirdthe degmeied areas of u e 8011;(where/ —
00k9 imts kil to be)beCOrrio equatizedisfabitized to the
&Ur,Walk q:4 subsoil moisture awiditios. The fen et
i lime required fcir subsoils to regain their meisturs is do-
I i
on the tree SpOde.5,toil type and the arrKicint of
I .---7---...,,,,ti\
--------,',,,,-,\ rad& For mcst trees,one wet seam may be enough
%.-. ‘+i for it.1.4,.fi-c,,nito. tn.regain 11-v," t t.-oft;:yr,t3'hell ,..0,- ,-. 4 g.
,,r A,„o.0„,,,, „,„,,E..,„,n ,cir.114A_ ....,._Net,,i,Ft:Matt&
1- 7-7 7','./79 --' .-----\\:\ of trees such as Live Oak,Poplar,etc.may resbit in rry,.&i,-
r, 4 -/// ,/,'„, ., ./..,,z-----i----', ',- \\
j /7/ 7 ,4-/ ,S,' ,\\ hire deficits in the soil profile that my require se ve rat
4 1 1/1 i ''. .4.il. 4 4/ (//Ye'"I\\\\ ,
( 11 ) ) ,,,' p' o t .„-- ; 1'0, . yeats te stabilize,
: , ft i / i,:----' _.,./ITL
i t V ) 10 -( ( i.\‘, \‘--,-------.,, / Remedial rnensures to cured Inc adverse etfecle of this
'
i
i I , \ „„ „. -...,,,...._ . -_._,...- / :
r -F4/ • , \ '-\\--„, --------7k;4-1 ., type of mil heaving are scirmwhat broiled,One Method is'
„-- I ir......"--sz"..i............--44*. i / i
1 "-I I t-,-- --P --51--rt,7,-k---‘-=-.!--1 10 raisa the entice foundation out of the potential Vertical
I: 4 l '4 -/-/— '-`-ii----„, rise of the soil using underpinning techniques_ Soil test-
? (6,:k----)--- •r
szT ;
. , '''t i;rH)will genotally show the PVM(Potential Verticai Move,
4 A i ; .j 5 men!)vir-Aues in the so ',Acre the trees were removed. If
k 0- ,
.1 \---.1, ,,,,74),, et 0 ) may tier) become necessary to raise the foundatien out
1 1 —
j,/ of this zone. An etternative is to use a vertical moisture
barrier. A combination of partial underpinning and the-
lioure 9. use of moisture barriers mey ail:743 have fa be used to
stabilize the foundation system
WO ati.W0a: kJ(' ROvoral years. Studies have shown that
ibis process can lake sevega years in the area where FOUNDATION CENTER 'TITLFIWNT
highly expansive clays are present, in this case,the foun-
dation
for the structure should be designed for the arifiCi-
There has been an ever,-increasing problem with regard
patod maXimum heave. Furthermore the drilled footiogs, . . .
to the interaction between trees arid foundation pc-for
if ussol rr led. be r.ilaced bolow the zone cif influence or
fr,ance Le.; kiiAid-Aori performance induced by under--
tee roots. This depth thoufd be evaluated as follows:
slab sower Wks. Many of the homes constructed in the
1550 Item period had cast iron, under-stab sewer PiPCS
The '1 be 'i -'''id below fill '4'-''"Ith 'C--, -
a:I Tr° Per Shp”- •4 - placed '' ' 9 "r"• or con- in clay soil. Nat lhe past 40 N - the 4' '
. yea s -iti of ik-N.;1 of
40,T1t,$tiCtiOn or the Zera Ificw9cr#'0 ItilEl- this unfortunate marriage has produced a proliferation s.f
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echnical Papers Page 2 of 3
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s&=,sewer leaKs &rice most 01 4)of the home the ullimitte will Mat tho foundaon subsided insd
insert:me osIvires iiitty=r a homeowner to collect on darn- 0 il-eaviLrg as on might antic:valUi.
axis e.ausod try Rich leaks,thew has been an attendant
amber et&itch claims filed 'ibis opinion does of course,involve a number of tas-sump-
riot-is Icy which.no proof e,XiSls. ln fact, there is title of no
Tptsay, tki c4*!nor tiros plumbing lkenng real roof that any sewer leak did, or did not,miso fou.h,
*.yrIparir and an Engineer to determine if the leek has dation deflections to occur. More testing and study is
eaumt any foundation feta:10C darti;ve ft is likewise typi- roquirod
esti that this mine Engineer witt obstenie hat the feirida
bon has dollocted downward in ifs center srection,which CONCLUSIONS AND RECOMMENDATIONS
is the opt note of what one might anticipate if water were
to be ineucqd ire-W epnov vaits. Other contradictions The design and ratenufacitt o'of rirriv'ot the material things
may be observed wtlion inducted the following= we LISfi a our lives based, to at eas some degme,on
some typo of research. Automobiles are designed and
O The te-hing of the damage appeared coiniciderital to extensively lasted before they teach the market, menu-
the OciCillf&toe of the sewer teak fazlurei 5 of appliances subject them to extensive testing
before new models are put up for sale), new tow pjod,
o There were plumbing yEil where it tests were riots must be given eAterisive testing,etc, it is then-Dame-
conducted, tie coils were cioniparattveiy thy.. what ignominious that the design and(itoMtfuctioh of the
ktridamental part of vitial is perhaps the most expensive
o There was always a re niable degree of correfe- Investment for most of us is based on tiltie,if any, current
den between the presence el the sewer te ak-s. and res--”rch; at least in the Wired States, Instead, we fond
the paints of deflection to learn in the most fundamental, and in the crudest, of
ways-by trial and error. The cosi of this process is born
o in a majority of cases,the mils ware expansive,the by the builders,homeowners,and engineers much to tit,„e
foundation was constructed en drilled piers or was delight of many attorneys.
underpinned using drifted piers subsequent to the limo
of original construction, and there were trees grow- We have, in this paper.pointed out Some of the problems
ing near the foundation Which were almost always that can be caused by our failure to learn to live with trees
mature, It is a known fact that the water demands of in-an urban environment. Although much of this discus-
mature frees tend to stabifize, Coufd these trees then sion was based on Houston, Texas, expenence, this in-
%Aide* become the source of additional founda- formation certainly applies to much of TeXas and to ether
kin defter:tons? parts of the country,as well All of us who are involved in
the design and corustruction of reddenlial and other-low-
in the 20(i) cases which we examined,the forego- rise buildings need to be cognizant of these problems and
ing oenditions existed and the foundation settled in to conduct ourselves aocordingty. This may require addi-
the center instead of heaving, as-was anticipated. tional pre-cwstruction testing and may necessitate the
An example is shown in Figure 9. In this case, the need for more expensive des4gns. S-43.me may say that
sewer system Good ocit be tested since it INC-Uld hold Mr Oliiirft may not be willing 1.0 p4V the price for such
no wr. extra work. So long as there are engineers who are Mil.
ing to do cheap work, the problems we discussed herein
We are of the-opinion that the introduction of the sower will tr,mir and we will be left to ponder why some people
water spurred the growth of the tree roots to grow to- are Mora witting to pay their attorneys frati than they are
wards the gourco.li"i The tree roots then extracted not their 8004KieS and or builders,.
only the moisture provided from any WNW kinks Which
Da-lined,but also any 100iStlf0 which was in the soil be- We hero pointed out the need for research. To the best
fore the leek ()owned. The presence of an urpdes-stb of our kndwiedge„ the Iasi 2 large research studies eon-
sewer teak then resulted in a net Suit moisture loss whrue dueled er residential foundation iwies.were the DRAD
kirge traer.i were ordimml,adoi3orif to the foundation with in the 113,60's end;he University of Texas at Arlington stud-
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:1"echilic4.11 Papers
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110
in the iffilo's. 'etre Ott krio-w of ta:t.iTtiti studie's, Texas Sexton of the P-now-en Scctclyci Givil Enw:et-is.
which fitA,trt been Candk.tcted at SCIlia ORM?r sites, but we Octotxtr 2, 1961,
betieve bta1 larder studics atv. ar.:totleti rittt nt-tly on the
f, Hams,Rict'ord've Airtntsottict, Prentice Hall Ciatt*f&
ls-sues 5stiscintritd heroin but on sitt in kz:tios p we
Tecirliolcvy, 1992,Pg
Some of the study arttas aed listed 1;,t6ow
B. ,fn4-Kil:, D. E &HOtz W.G.:ExpariSr0&AS -The Hd-
0 A 1'00601'0'11p ettds!a be(fevak'rpod that would ad- CFI SaSter FVrAlefiril-ASCE kikg:.43.No 6,Noo
dreits the tree type(species),dfstanoe from the leurt- York,NY,August, 1973,pp 49 51
datinn, and he'tcttil of the bee.
o udies similar to thoz-.se oroldunted by Biddle should S. Trefas, Wond Book Encyglopede, 1%7 Itedturne 1 Pg
be done ilsifig trees more typcally found in the Unit:A 34.
Stales Paks, PrRtarts,China k3ely,elc)Th clay scAs
varvirici vtieather patterns that are typical of this 10 R. Odserail; The intklefre of vtN;teferion c the swelling
and strinkinia or clay soils Btitain, The Intlijesx.te ef
court try.
Wa9.4..t.N.rt on,claa, The Ins5tuto.--1 of Chnl Eingineers,
Thkwrias Telford.Ltd,1a84.
o How to better cies;go floating statis oat Yanuid resist
U-e rifled of trees
11. I J Freenian,et at.lies Voir tloese CilCc trisittt.
rim of Civil Err ests3 Builring Rasearch
o Devetop a simple, rnatharnencal module that vo.tid it-ottas Tetftd House, 1041,P 20
rotalct stevtint fetAtt;,trk,,e nidsture fen-loyal, and
wit moven-leafs 12 R G.Bidcle;Patterns of sod drying nnd mt3isture deficit ni
the vicinity of!fees on clay st-tjlti:. The influercool'
..:a of y
Pelhaps:the iaterrnation contained herc4-11M11 help in the atatib.aon clays-,The Institution of Crvt Engineers,
trc-
rnasleiford,Ltd., 1984.
search for i-escatch dollars,
1:1. Wray, Warm$ SmThuiHonie is lint!,op,t.WAntli..A
5,0 Blot frart.RA_PHy
ASCE PLA-Aication, 1995.
Rf.t.ped C. Davis, Resit*ntial FeLotidatioe Pglitt_moncg, 14. Godfrey,K,A,, Fglarks-ive arid smith,*soils„
The Cu-tstruction Research Centel', The .tirtive,,sity of Mg problems being attacked,?ct,,,oEhairt-PlID2,z.f%S.Q.E
Texas itMmiiçion,Septentu,r 1, 1972, October197.6.
2. Rcteti C.Davis &Richard L.Tucker The tkve 01 Trees 15. Tucker,Richard L.&Poor,Arthur R.;A sttitly of Rott4vi,..7
Benxi Marks in -Expansive Clays Trix.hnical Note, „Tt slabs Folimied on wive ciay So'is, Joomat of the
Mo4r-pinl mat citt the Miertcan ttteet Div cif Civit Geotootriical Division of ASCE,April, 1979.
Entirts
16 Dutton,Jim: Foundation Repair Techniques, Soil Struc
3. Ernest L Buckley;Liwt.3iiing bu ngi Mtsject.jon retainer of 1996, FAXi10r, Parr Reickintial rS4tton-Grourvd i'ound*-.1tions, Coliege et rnanc-e Corrinttic „ 196G.
Ervineeinvg, line:et-5;4,01 Tmtycis at Ni on,March t2,
19:4
17, T. Onrrri, ia HaS Y013 House Gol Cracks; Institn.,
ton of C'M F.rtgint-Ars&Built:Jag Res>serch Establishment,
4. Ernest L.Bui,;kitee,Lcsserott Damage on ftesatrilial Stab- Thomas Tetford Housa, 1944,Pg.20
en-GrCtifYj Foirsdakris„Construction Research Centar,
C°IteCle of•Erg4rfeelingr tirjvers4 et-riax‘ls '411'319t on, l& Lawson,M.&O?CallegItan,0:A Critical Anatr.sit*,'of the
March 12, 1974.
Role ei Trees tri'Darringe to Low Rise Bisildnos,Joun
ei Artorigitroie, ski 21C2),Pgs 911.97.
5 Paoi 1.Ittran-ter& Tftel.-.,dizie T. 1(..cizlowst,;:.: P ' c of
pp 292:295, McGraw Hill Book Cort-tpany, 1960. 19, Personal commi inicabon with Di.RonaldN.ewfori, Tans
M.titan reratilry, DepoetrrIttet,
P 'crcttnu'rJW VV.ft D-EgliS Refi:b**1014d CDT1-
SIrtictnyl Preotarns Pruserfad at the Fell Meeting of On
if)
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�,"4� .�� �
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� wad � � � . �
e . e Engineering n Testing.
': 4s Founded in 1985, Geotech Engineering and Testing (GET) is a multi-disciplined organization of
registered engineers, geologist, field and laboratory technicians, and clerical personnel who
�._ -. combine their technical capabilities, past experience,
dedication, and enthusiasm to offer the finest service
through integrated team effort. GET has a staff of about
50 engineers,geologists, technicians, and support staff.
Our services include the following: g i �
Geotechnical Engineering including soil borings
AO:14Pb f` IV and laboratory testing, engineering analysis and fr %,.
recommendations regarding foundations, paving,
construction, slope stability, faulting, etc.
a Construction Materials Engineering including earthwork, asphalt, steel, and concrete
testing during construction.
a Forensic Engineering, including foundation,retaining walls, slopes and paving distress
studies.
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a Environmental Engineering including environmental site assessments, monitor well
installations, and underground storage tank contamination studies.
. t�' wit _A -
8 5 g
3 tom ,:r . 'Disadvantaged Enterprise
: , €
P . GET has been certified as a Historically Underutilized Business(HUB)and Disadvantaged
" "ate- Business Enterprise(DBE)with the State of Texas, Texas Department of Transportation,
Houston Independent School District and the Cities and Transit Authorities in Houston, Dallas,
San Antonio. Austin and Beaumont.
a s � • _*4-W4t)"' Niiiatti*. ;Air 11,7 Our insurance coverage includes$1,000,000 general
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Technical Papers
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DE:VELOPMENT DESiGN AND REWiEDIAL MEASURirES
LiCiiiTLY-LOADED STRUCTURES FOUNDED ON EXPANSi VE
SCALS -MTh TREES MIND
ilavid At Eastwood, RE and Richard 1111. Pew:at-toy, PE
Geotech Engineering and Tsting,Inc Pevertey Engineering, Inc_
BOO Victoria()rive 1207 Regency Square, Ste
Houston, Texas 77022 Houston; Texas 7,036
7 t3-699-4 000 7 I 3..977-0328
ABSTRACT
,
I A review of the current literature, n the United States showS there may be en.Eitisence
j approachor r50 deSiOn 05 ttattly-hlatiet.5 structures founded on expansive ci s
I trees are mvokied As a result, many_such stiuctuij s.v-44-)tcli,have experieiaciol distress
I of the lack of Inc c!„,r1s:ctof thcn nf thc, effect of It ee, n!these 11,rictures F
of this paper are A part of 3 Houston organi2ation matted the 1-ot:ridntl Performance C
One of the tiCttVlii.eS 01 lb*COMMittee s 1110 rtwesttqahon of die adverse effect that tpit
and/or the removal of trees can nave en lighttroadett structures this paper lock,oeis
I of this achvtly, and also int-Awes the results of a literature survey,a teVR1W of the Cailurr
I foundations whose cause nas been attrtbuted to the presence of at-idiot the, rembw
design ret,"ctretMentiaitOns, Id repiirs itee6 il8v0 pittriwry
INTRO:WC PON meal Note which provided data which sr
Oak trees located South 01kfingtort Tex
A significant number of residential buildings were con- tar rnoverneats varyin/ from 1.2 thCha
structM in the greater Houston are in the 1950 through between the end of the summer months
1970 time periods, Many of these buildings were founded the winter months, The University of Te
on expansive salts and on budding tots, which were void conducted an investigation of 69 abandi
Of vegetation, Trees were then planted atter these atioings vettri were founded on clay so
leg were sot and eventualty the trees attifiredand CJused among other things,tot the,extraotion c
fOuntiatte faUre to occur, Corrective measures genet the soil through the roots of frees, caus
included ine underpinning of the iounuation polio- severe deriectio(r s ih101)flattiOftSi., irs)
(fief Wahl using&lieu piers and iator pressed Oes. When presented data which straed damage
Plat s were ti:Sett iiipproxh had, at best,a iitd Oa, carieil by treos. Kramer and Maz1ows*
Fee of sotte-so, Tha tirrO of Wu rt.rriode,whereby tws comparativoy high trawkacien rates o
nose the settlement of the °,1-3ftlf residerdiek and 1990 in 1987, Pe,iierley and Henysriil
ottieri,aw-rrea berktings,has rerf!biqid a sionificnt ameent sured defter:60PS id a residendalttlirit
of pribbrity WPM, !lines,rtintt, as t res,It rime own. been prtxtvcert fjy rierirny trees,
ers,Oiidinn reroodetinil coornerots, home,framers,etc„
ty.we become;mare of this problem Frnra Ihts,an nom The MoOner 411 which trees can cause dc
industry has qtthiliti which provides ineasureS to tOntrOl 11611S n residentiai stab-on-ground found0
this OtOblerrt tote, been well documehted. Simply,sta
satisfy tnev need for soil water, trees ca
Some notice of!h manner in i.vrirri trees can produce soil upon which the outer eige of a buni
downward detteCtiOnS a msklential siahongreand faiffl- suiting in the shrinkage of the soil with hi
rialions began to appear in the early 1970'S, For example, of soil supped, Foundation distress anti
in 1972,Davls1"summarized extanu pars which indi- causes have occurred with such regulaiii
cared that neenby trees C01,43 ,a,tiversely ahem fotinda- Houston area as to have CauSed a major
Urn ociderrnance. Davis and lil-Cker"";put-4111Iva a teen- *fundamental loungWion Oft:Pgi and cense
orAste.d `q79Z Spfing.,Ses,i;on of tfati-Tift ASCIF
Cack here to continue
tttp.//geoteeheng.cornIpapersheelipapers light!yloadect I.11E1111 2/10/2004