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Mr. E.. M. Polly Physical Plant Departraent - Chicago 1716 Jest Taylor Street University of Illinois Chicago 12., Illinois
Dear Mr. Polly-:
113 Talbot Lab .. July 6, 1951
Thank you for your letter of July 2 with the structural drnw-1ng $hO\,fing the revised foundation for the staff apartment building et the �odical Center.
�he extensive foundation note;'! on thir, dtm7ing indicate thut the architect hRs given serious considerat:on to the use of the machine drilled sub-pier and has tried to antici;nttE. c number of the objcctionz to tt.e procedure th;,1,t I tlf.lve f('lt. Nevertheless I still feel sor-o reserv_ti0ns coneerning the desirribility of this t:,;,e of foundation.
One rol�tively minor comment is that the proposed bell on the caisson does not satisfy the requirements of the Chicago Bu1ld-1n{; Code which gt( tes the! t r.. bell sha.l.t be at least 12 inches thick at its edge and that the sides shall slope at an angle of no� less than 60° with tho horizon�Pl. Th� proposed bell shown on drawin� Fl.A h<1S a very much flatter slope nnd I \.tould not consider it ado.uate to trensfor the foundation nressure to tho rathvr small shaft, This objection could probably be overcome by using the reacer to e�cavate a vertical section about 2 feet deeper below the bottom of the l\elll.isDherical bell shown on the drawing.
My principal objection is as follows. According to the dra�ing the bell is to be forl:!.ed in the dry. If the sides of the vertical shai't encounter ·water this shaft is to b� seFled by means of a easing. However ., there Ls no gur�ri ntee that the waterial in which the bell will be formed "''111 be dry. If tho bell 1s formed in material containing a silt or sand seam wt1 .. ch fe(;ds vater into the bell there is no possible way to control this ate�. In a hqnd dug caisson tho water can be removed by baling or if nsces.sary, by puiapinc. This rec.uircs r:.hat a r.1an oe sent domi the hole. If sludge falls off th.e top of the t1ell
Mr. E. M .. ?olly Page 2
and lands upon the bottom it can be cleaned off successfully only by hand; indeed, the presence of a rather thin layer of sludge on the botton of the bell ca.n hardly be detected except by a visuai inspectiono The presence of such sludge on the bottom of the caisson could give rise to settlements of the order of 1 or 2 inches. This condition has been observed ithen similar pier have been constructed to bedrock foundations. Therefore ., in order for us to be safe I feel that the bottom of each caisson should be g!ven a careful inspection just as the bottom of every hand dug caisson is carefully inspected. This :neans� according to tho notes on the d.ra.wlng that a easin& must be used in every shaft and th!J.t a man must go down into t.;-.er7 bell. I personally could net be induced to ::nake such an insrec�ion because I would consider it very risky to have to get 1:iysel.f up into a 2-foot shaft if tl1e side of ti-»e bell should begin to cru�ble and collapse. Yith the lPrger diameters of hand. dug caissons a man has a chance to climb up on the lageing and get out of the way of falling material.
Unfortunately I I am. inclint.-d to believe that there is conslderable likelihood that silt and sand flay fall from the bell on to tl:e b,)ttom or the caisson during and shortly after tl!e bell b.as beo� for.med. If this ocours the building will not have a Sc.tisfactory fou,'"ltla·tion. The notes on the drm:ing indic..:i te th·. t the contrc.ctor must d01n.onstr..:.1te that t sub-pier const. ... �ucted in tho pro.r:osed c•nner will be satisfactory. This re<.uire:11en c; shoultl by all means be adhered to. Moreo•...-er I the test caisson should oo located at some .).lace where failure of" the procedure uould not er.danger the .i)ropo�ed,foundation. In spite of the precaution of'. a test pier, hO\ over., I �m inclin, d
· to believe that the silty materials above hardpan at this locality are sufficiently variable tiat the success of a te'itpier does not necessarily mean the success of clll piers on thejob.
I think it 3hould be made ouite clear before permission isgi vcn to use this novel type o.r foundation tm t failure to produce a satisfactory bel1 and to get satisfactory conditions onthe bottom of every bell would lead to the re juirement that thecoutractor sho1.ccld replace each un�atisfbetory pier by means ofa hand dug caisson of customary diameter in whi.ct. condi tlonscan be safely observed and from which sludge and stteping 1-1atercan be removed. This requirement, if necess·"""7: would greatlyadd to the contractor's cost,, r am not sure tht1 t he would bewilling to accept the res�ons1b111ty. Nevertheless, I feelthat to protect our interest sooe such agreement should be madein advance of construction.
Yours very sincerely,
cc: tir. E. L. St9uffer Ralph B. Peck
RBP/p
UNIVERSITY OF ILLINOIS
PHYSICAL PLANT DEPARTMENT-CHICAGO
Prof. Ralph Peck 113 Talbot Lab. University of Illinois Urbana, Illinois
Dear Professor Peck:
1 71 6 WEST TAYLOR STREET
CHICAGO 12, ILLINOIS
July 2, 1951
We are transmitting a copy of the new foundation plans and details of the staff apartment building. The above shows cassion construction in lieu of pile construction. We would certainly appreciate your comments on this at your earliest convenience.
If you have any questions pertaining to the above, please feel free to contact the writer on the Chicago Medical Center campus at extension 531.
EMP: ja Enc.
Very truly yours,
t.rn.?�E. M. Polly
r IA/I�� SUBSURFACE ENGINEERING CORPORATION
To: Casey and Case 53 WEST JACKSON BLVD. • CHICAGO 4, ILLINOIS
['ate 6/20/51 Sheet.il_l ___ of...::2,_, __
This report covers t.11e soil testing of the soil sample3 ta.ken on the e1te of' the RESIDENCE HALLS for li!SN, 810 3. ',··o::.cott street, Chicago, Illinois. The soil testing prog1'am was ordored by M:."' .r::ase of the firm of Casey and Case.
Two test holes were IllR.de on the site of the proposed bull:Unb using a drilling machine developed by the firm of Casey and Caae o
The holes were excavated to a depth of 4lo0 ft. l:.lu1, 12 inch seumloss tube sample::i v1ere taken at intervals of five feet 01· a. t cucl·� chang0 of strata. until th� fi�o.l depth watJ r·eached. The uoil samples. were taken l)y the standard :methoc., ,·d. +li the en.:eption tluit the samples, bec1...uso of the hardne�.J of' the clay layers, WE;I·f;
dri von w1 th a 140 lb. hammer falling 30 inches.. With fev: cxcer1tior.o the san,ples and the si:tmple tube...1 were removed .:"ron, tho so.11 in good condition and the soil was not unuuly remolded. Unconfincc conpr<'soi ve strength and vmt.er contents teets were porfor,ned on the soil and the results shc,wn on sheet 2 of 8 indicate thu t· they were in good condition and gave good test results.
In comparing the resul.ts of the soi] tents and our v lsuo.l obscrva tion of the soiJ a.s re::novet.: f1·om the test holo v:1. t.l'1 th.e soil logs a.s shovm on Sheet No.A-1, as prepared by NAE3S and MURPHY for the p:rojcct,we f1.nd that thoi'e is e;ood agroem0nt except, for norrwncl1.1tttre of some of the soil st1•at.so
The material encountered at e. depth of 60 .. o foot is a ha.rd s toney silty blue cls.y kno\'rn local] y a.s 11 Hs:rd Pan." It has high compressive strengths and low water·contents.
From thj_s soil investigation and others in tr1c area. it: is known that the 11Ha1 ... ·d Pan 11 str1:;.t.&. is uniform in depth a:rrl that th<-:: underlying soils arc as hard or harder.
SB/fo
SUBSURF'.£1.CE ENGI:N.EERINC CORP01{A rrION
j��� Sid.nay B ern1an
• Job N,,. -- --- ---
CORPORATION
____________ Date , I\\ 1',) f= lcl '5..1 Sheet_2_of_ _.z __ �
c.L--'2--�..U.LL�!..-.ti��l.kl���i.,._..c.,.-=..c:--r..J....I.J...l.l'-!A.......X��o�L�C�Q.uJ.I.Sr�-CtJ1LA.17
4 o�o"-1---4--1 41' 42
° ��--t
'5(;· 6'.i.-.......-1---1 51'-6."'J.L.-o:...c.-+--1
�" t �---+--t 60: O ..µ.,;,..,-----i
1oc·�-��---1
CLASSIFICATION
I II 'I
HAl21) BLUE CLAY� DEN5E ��EY!: S/:l.t-..lD.-'.SILT·50ME STON(S 'i
N/C I 1.4% 9u (;,.3T/5Ci.FT. ; 11I'
I--IA!l.D :.,\LT'{ BLUE C.!.h( SO Ml:. S TON. ''i:,
w/c \S.� %· 1 ..... 4.1 T ;r,,1
11
HA�D 51Lf'1 SU.l C , t,..: 1 Ii �OME STDNF.:S I
'vJ/C 17.{,So 9i...1. 3,7 T/�Q. FT. j
I GiR.f:'{ CLAYf, 51LT I
:OM£ ::'..1<"'11..:, w/c 1q,q r1(' 'e 2. '51, �,--;. n.
HA. Q D $ \ l T Y � . ' "'• ,: f
P ' 1 1· CL/\'t
\" :. 11 I 0/.:, cl 1.1.-t : • e, T f" 1k � i HARD ;1L·ry :. TC, lt.. 'I t3L\.iC ( L A Y - S .1' J'\l D P �1(. t:.. fr T \'v/C 10.e:c · 9tA. :t
+ POvi< TE �·r.t- NO Tf:"$T
BORING NO. 2
\'N"
DEPTH �. CLASSlFICATION
.t'r'
'/
-
r ---
40� M..._,___
c.---41-0 42:.C .�
,.-
I/// ,II/
----
I
---
V/// ,., / ----
--
� "'-' Sb·o· - '5T O .. r--. ......
I
bo·-o· <-,l-0
.. Q'-0
1----
/// .- .·
'' '\.., "'
-·--·-·--
---
-
-
---·-
AND
HM:b S°H1'.1 f.'( SILT'( SANDY SLVE C.1.-1-�}
w/c 12.0'k 17 1� 4,1 Ti' SQ.fT.
HAQ.D ST6"1E.Y ':.1\L";"Y tE.)F. CLAY
w/c 12. 2 1'0 • 76"f[--
·"\ '"( t �... . ' ,,. (
HI\� D � I L.11 EH l E ri l. 't1
)1�i::. 'STONE, w/c 1e..1·1,, \L ... 3.1-r/'q.rr.
c.. t- r ( c L I\ 't ::: ·r ·-:- 1 _ ·r wA 2 c ·:3 "I� ,1 l4 1, " Tit:' Q. i· r.
NOTES: �\ Jt>1vE 15'-'5"' vVI.JE. 15 ,51Date ofbotings: Started,;
2.JuNE. If: ·51 Finished JUN£. 18'51 Date of tests: :. t JU t� Ii \ 6 I
Type of drilling: C A. b I F OR. l\ J 11\ A I l C 'is • Type of sampling Tools: s ti E L By r VR eSize and depth of casing: __ 1\j'-'1---10..u.s.Nw� .... ;..----------Boring stopped because: lLE:..:1).. U I R E 11 D E Pr;.
"N"-Relative Density-Number of blows required to drive sample spoon 12" with 140 lb. weight falling 30".
Fixed datum used _________ _
Remarks: \N 'c WAl .= � ( ('dl r.:-�� Tl Cf, D�-'t Wf:l�lff) ClassificRtion by P,.: (f}'l(\ I\
Fore1nan�_c__ ""'�'i�L"-- ____ _ qv... -NCON-:-INEC' Si,<1-MG1 THJob No._-__ _
