ML20094H929
Text
,._.__.f...___._.__
3A Dadd e$
vs Acs O.
9 3 bnt A DISCUSSION ON THE EFFECTS OF PHASE II CONSTRUCTION ON
/
3 THE AUXILIARY BUILDING FOUNDATION This discussion presents reasons why Phase II construction 11
-will not be detrimental to the foundation support of the auxiliary building. Phase II is primarily the construction of several 3 fto by 6 ft. hand dug piers and 7 ft. high by 6 ft. wide access drifts necessary for access to the pier locations. Phase II does not. include h
any undermining or removal of the supporting soil directly beneath the auxiliary building. Although there is lateral excavation adjacent to the materials supporting the auxiliary building, and there are
' excavations for hand dug piers, as explained below, these excavations and the construction of the piers will not be detrimental to the auxiliary building foundation.
The first consideration must be the strength and rigidity of the auxiliary building structure. The massive east-west shear wall is capable of redistributing the building loads to the underlying. soil if necessary. A preliminary finite element analysis of.the structure indicates that approximately 7 kai maximuy increast in rebar stress will occur if a 20 ft. width of soil were removed under both the east and west ends of the electrical penetration wings. This is a design case far more severe than any condition that could exist in Phase II con-struction. Therefore. this acceptable increase in stress provides assur.nce that the Phase II construction will not be detrimental to the auxiliary building foundation.
In the actual case, there will
{
not be any soil removed from under the auxiliary building; only a
[
minor redistribution of the soil pressure bulb will take place, as a result of the construction.
4 Construction procedures are an important consideration. For the access drift, the procedure will be to advance the excavation approxi-mately four feet without lagging. The unlagged excavation can be ex-pected to stand at greater than 3 vertical to I horizontal during this stage of construction. After the excavation has been extended, a
{
steel support frame will be installed four feet beyond the last in-place frame. Lagging will be placed along the sides of the drift between these i
two frames. Previously excavated soil will. then be packed behind the lagging to restore lateral support to the unexcavated soil.
The pits will be constructed by the " excavate a foot - lag le a foot" method in the fill material. Immediately after the lagging is in place, it will be backpacked to return lateral support to the surrounding soil.
' These construction procedures for the access drifts and the pits are by controlled hand methods. They are also very localized con-struction activities.- Additionally, no two adjacent pits will be i
worked on at the same time.
4 8408140163 840718 L
(
-RICE 84-96 PDR l
',"7~,_
L.__,i.._,. _ _,
...._,,.1,,__.
....__.._,.___.,_.-_._.____i_..,____Z'
4
. s From field experience and the references listed at the end of this discussion, approximate limits of significantly disturbed soil adjacent to drift excavation can be expected to resemble the shape shown in Figures Al and Bl.
The maximum horizontal projection of these zones of influence is approximately one half the height of the excavation.- These figures, drawn to scale, indicate that the expected zones of influence do not extend to the soil supporting the auxiliary building.
The effect that the excavation will have on the " bulb of pressure" beneath the auxiliary building must 'also be evaluated. The vertical l
pressure in the-supporting soil reduces with depth. The pressure lines on Figures A2 and B2 represent the bulb of pressure corresponding to one-tenth of the contact pressure beneath the foundation of the auxiliary building. Thus, it is seen from Figures A2 and B2 that this one-tenth ratio line does not intersect the access drifts.
However, there is an overlap of the zone of influence of signifi-cantly disturbed soil from Figures Al and 31 with the 0.1 pressure bulb. This overlap will cause a redistribution of pressure, but because it occurs in a zone of low pressure the effect on the auxiliary building will be insignificant.
In a similar manner, excavation for the pits will cause distur -
bance of the low stress regions of the pressure bulb created by the auxiliary building. Again, this is a minor redistribution having an insignificant effect.
A contingency plan for ground' stabilization will be implemented if the soil is found to be instable, or if the instrumentation indicates movement of the auxiliary building. trat bne. bm "3 Cha.) gew The above discussion clearly indicates that Phase II construction will not be detrimental to the auxiliary building.
REFERENCES 1.
Foundation Design, Wayne C. Teng, page 125, 126.
2.
NAVFAC DM-7, Department of Navy, Figure 1348.
l:
3.
Rock Tunneling With Steel Supports, Proctor & White, page 62.
- 4. ' Cofferdams, White and Prentis, page 61.
(
l l
l i
~^
~
a
'I's a
o.
. :a -.
y.
N
.9 N. (
?. * '. '.
..a.-..'
~
Hoit or' reocfor-
\\
g s
'//ff
~
.,9
,//
. n
\\f//
\\
I 4)k(
i n
y
/$
]
l Il b ' I Yl.'.
^
-i l
ll l
e 1
hY f/
L Conc e e Q9<f
.9
/
5.%ve-Stocell l
i I
k / /
1 I
I I
s
_-F U
'9 "A
e r.e l
ll A
tr-
-4 l
ll I
PL AN
'S llf/)
I ll l
l Scate:'bt;o"
_ _s '
'a ll T
ll l
'r w//
i 11 i
Jj i
.Il 4
m m
i l
l l
1 ll l
- re -
l I
y l
i 33-I 3:3-I S
i 1
1
=
ii p.____
L _ _ __ _.j j
9
_ _. J 4
l l
l i
IB I
+
i i
I L_________
I I
l!
p j _ __ _ _ m
==*.=.=j e.
_=m__=====_
e
',9 hi l
0 I
0
-N li l
m l
i
_ __4__ _ ____ _ ____ _ _ =
j 3_ _
2 I
i l
v
.s.v s
n o.-- -
~
l g
.T.'
N9 1l E
r~
l~
- -a e
m n
,r,
,i
_1 a
i
__[ k
._ _ _ g l
l l
l E
N8 l
I T
T l
l g
o I
.I T.
I l
I l
l l-l I
I i
i l
I I
I P
, _ a_
l
_ _pg _ _ _ _:_g 2
,8 1
i il i
I i
L, 4:9-
_'v,L 4to-Stc-l 4to-i--*4 ' 3-
_ i d'5
_i FIGURE A
l l 82 1
.. :-~ :~
z.
c m_
.Y i
r.
v-4 n
AlJX/UARY I
l F/VP 1
a BLDG f
.i
'r.
- :o.
~.
. a,.
1 i
. cv ;..
'. *or Q. *
-,, - 'Q'.*
9h.
f)s, M^
.g.
,. Or.. - -
"6E.*-...,o*i 'I '..[.1..~,.'.'...* 6 7/* ^ Q.'.*
2,'..'. l. 5[.~[i ;
... ". ' :,f i. ; ;. s. *. ;. 8
, J '.
.s
...s....
..'.... ::'..,......, t.. *. '. i.'.;. : '.,.% : ~
- ~'
t
~..:.: *.,:, ;i.t '. '..,:.:G..;. :. a ; :
.. ~..
- 1..*,u.. * '*:
...... ::y:..........
- ,A.....-.......
=..
.....~.
l f,
.A.
L N/f r
T c) l Q
ACCESS
^
APPROX / MATE UMIT* OF 7
S/GN/F/CANn.Y D/5TU' E8ED i
rn D2ifl~
SOIL c
.t i
I r
1 I.
t.
p 2
1, I
j 4
i 4
i f
yo,
.a w..
8
- : (
n
]
.d, V'
't.
- .o. 6-a
. ' ' ~ -
x.
~
$ECTION As i
L y
1
- d5..
' 08-.
.O' g
i (D
i N
i i
H F
.I
1 a
e I
g:? s. &
AUXILIAin' N O Gi.
.'. '.o'. ". k. k:'
7~UE:5. N ~
8 L O G.
i c
..-.we i
a p
=
~
..q.
- a q,. ~.....
w.....a.
...a
.p.
a..
~
...a..
a..
a ~..
...a.
a.
- p. - -
.,.a
+.
,..a..
e,..
~6..
.o
.. a.
a-
... o.._. ; _, p
.... a.... '. a.
. s.,
...e
.......... ~.: :.,
l T
EL. 60S O r J 4
C) l.
C f
l i
't ACJSS DR'IFT 9
w s
I 9
h'~
i APPk'OX/ MATE UMIT OF 4.
5/GN/F/CANTLY DISTu2'8EO N
~
So/L 9
E.
4
.c l
U s
a wwrmm err /s ner ww W
-1 h
I 4
s l
l O
\\
PI 7~
s<
s o
i k
k W
d N
4.
i:
i*
fs
Y Y
l 1,
A M/L/ M F/VP a
BL D6 6-1 1
F v
j
,,. 7 0,
o, O
g c
,s.
a c
y
- -;.
- ;.,? p '. N I'
m.;:..
- =.
'. =..
..:..... p..
_.:.i.;.
i; q....,
i3ji ar, r60*
i st l
't l
71 e
R O
C ACCESS X
m DRIFT APPROX / MATE ONE-TEMTH OF i*
3>
CONTACr PRESSUEE l./NE N
i.
i
.I i-E l
/VatW/Q s
's
- g :.
t
. o.
1 5
i 1
p.- g o
i N
O'.
o-e 08 05 os j
g I
4, ll $
SEC r/ON '
A2 V
!l 4 -
W6
e i
i
{
.)
- A.;s.;A---
AUXII.IAE Y i
8L DG.
...o '. ' '., : 6.;
7~U28/Ni~
8 L D G.
. a...
- s.......
i
... $.. :. ' 4 ' :... :... >
...,.. {...
... :4,.
w.
.a 2.
.p:
- a..
....:...a.:
.p...
.a...
...a.
...,s....a..n.
..A
+.
.a..
.. p. :
.. ~..
- ..f...s s...
y..
.. b. '...
. -b..:. ?.
- l.
a.
A q r:
....o, p
p,
.....s.
. 3..........:..
......,.. v.
- .~
m El.6080t J
= Goof i
O C
j E
ACCESS l
rn t
DR'IF7~
v l
t s
i m
n APPROX / MATE ONE-7~ENTN OF s
0 CON.rACT PEESSUEE UNE s
i d
^
4.
s s
k.
L-2 I
3 i.
8 M % MV/AM V TM// Nr hur/
i 0
I d,
N f
l-I s
l N
SCC T/OA/
8a
)
g i
l t
P/r z
0 i
t i
r i
W
,)'
4l.
t N
i i:
I I
s-
~
i sic. ( 7 sinss im iowin seur:4 125 Let L,,,, = lise load + dead load for the column which has the largest G = surface load; live load l dead load ratio; o 4=a' 8ad3
- depth of the given point; i
L, = service load for the same column;
,., g.fy: f;s. see FI. 6-9; E
= dead load + { live load for ordinary buildings;
\\
y, = angle between line R and vertical.
q,, = allowable bearing pressure as determined by the principles T
Based on Boussinesq's equation, the f'
I discussed in Sec. 6-5; r#
n vertical stresses under continuous, rect-angular and circular footings have been y,, = design pressure for all footings except the one with largest h. ve computed. The results are shown in Fig.
loadjdead load ratio.
c$
6-10. In these figures the magnitude of vertical pressure at variotis points are g
Then A = area of footing supporting the column with the largest live
- 27 '",, given in terms of the bearing pressurcq.
I so load, dead load ratio.
{
o For example the vertical pressure at any j
" E'-JI4d n.4-9 verticalstress due toa poiniload, Point along the line 0.2 is equal to 20 l
9 s
1 q, = LJA Service load r+- s
,,un.rar pen. ore, e
. Area for other foot. mas - ---
VJ 6 6i6 6 6ie 4
s f
l **'
J e
I ase 6-7 Stress on Lower Strata i
i
- 1. For stability analysis of footings, the pressure under a footing may be i
ce a
assumed to spread out on a slope of 2 vertical to I horizontal. Thus, a load d
Los 8c l
l
('
G acting concentrically on a footing o a,ea of roc..ng = a = t
/
ts, area of B x Lis assumed to be distri-z l
buted over an area of(B + Z)(L +
-i A
/
l
{
un.varm Z) at a depth Z below the footing, 4
i 208 pressure e
/
Appronimate pressure (a) p.ss,' O.707a F.ig. 6-8. If any stratum of soil is
,/
a, o, pin z.,,,f,,,,
4. i. d...... rc' 0
v c
inadequate to sustain th,s spread-out i
1 s+i
_ o..,ne,e,. s pressure, the design bearing pressure
[;&66,;;h
)
~
should be reduced. Ilowever, for a ng. 4-8 Approximate distribution of sertical two layer system of clays, the pro-pressure under footing.
g,,
j 05 0
cedure described in Fig. 6-11 gives
[~
I} l
{
I li.o as 3r-- -
more reliabic results.
,i
(
, "8 I
i 2 For settlement analysis, the approximation abose may not be sufficient,
'5 and a more accurate approach based on clastic theory may be required. All t
-08 j
l clastic methods are desetoped from the Boussinesq's equation which deals ts 28 with a single load acting on the surface of a half-space (infinitely large area and depth).
ICI cos/s (6-$)
5
==
q==
ng. 4-10 Vertical stresses under footing:(a) under a continuous footing:
where q = vertical stress at any given point; Ib) under a circular footing:(e) under a square footing.
f t
i
l l
.EEE OUTSIDE D'MENSIONS OF PILE GROUP IN PLAN : A x B, (B)lS SMALLER DIMENSION. PILES l
STOP IN TOP OF COARSE GRAINED LAYZR h LAYER @ IS UNDERLAIN BY COHESIVE STRATUM. LAYER h.
n : NUMBER OF PILES.
NOG nog l..
..I l....,
~
~
~
y ////Ififfff
. f...
g.
IIH f f fif,/ fifffffff f f f M
}
4
\\ 4 Rh
'H,g/ WO
\\g K
Hg C
" a&
f y,
H I g
j -8 i
- g : 0 f
B e1
'$!/ffff//
//// // / // // //
I"~[ nO 2
-/
"OG
\\
600'"-
t-G
\\
600 -
\\
H2
/
\\
H2
\\
g f
\\
\\
/
C=0.
/
C 0 li t I i i i l i i IM c :
I' l I i i i i i i l '4 J ' :.
M
//fs / //////////// ////////(///f / / \\//// //
'I/n'f "f/// ///// /// f iffilfillf / / l l ( \\ / // IfU
/
\\
\\
/
/
g
\\
LAYERh
\\
LAYER @
\\
f f
e' T,C,#3=0 s
-/
T,C3, #3=0 s
3 3
3 V L JJ_LLL.LJ. LIJJJJ':1 l' L JJJJ LLLLLLLLL'l DISTRIBUTION OF PRESSURES DISTRIBUTION OF PR ESSU'1ES BENEATH POINT BEARING PILES BENEATH POINT BEARING PILES Laren @ os contstut (p = 0)
Laren @ es contstonLiss (C a O) nQg = utrona rt Loao ca9acirr or snou9 valLunt in Latte @ INr C so Qg a uttssart capacerr or sonsLt 9tte
,, geoy,o,arta os nr ot9tn satarte inan tutsnr or 9ILis neto nor at ist stLor 109 or Larta Q racLuoto on a!9Leto Loaol.
Ir p ren (i) Is isstarlaLLv sinflan to parLueron tarta m rn,C as to Lo rtn Q, onts en negrnos res.tu.
Post s9acons $ sa:
or 4 correns sacarLv Inon 4,:
PILE staCins 4 sn:
nQa = (f, H,Nga
- 0.4 fg BNys) A nB "OG " U"* "t* * ##Y* 0"f'l '
- 0
- 2Ca (A *a)Ho = A B 4 H,
+(A *e)st orr fu,*-aag H.
f PILE SPACING r 16R: nOs = n(Q,,H) 9tlt $9acons > Isa: nQ =n(Quts)
Qu/} = (f H,Nyg + 0.4 (g BH g) JfR g y, g g, yt,, g,4 (, gyr,) j[gn g
u t 2[a JIR4, = ffR* $ H
- lTRf % ?Cn f H,3= KR"(,H, e
von allt s9aCins stretta en ano Isa, entin90La rt strrten int valuts ron sn ano ren, ran earta nean to rat snouno sunrict. susstorert Ane von fa nno Yone ron Ys on rnt asort ronsulas. onten90Lart stretta intst Lunors von onttantorart rasen LittL.
in anr cast rNE PosSIBILIrr or railunt on cLa r La rta @ tanto to contes ton (89.
nust at enstsrisarto.
rnis IS PantlCVlanLF Intontaar Ir Larta @ es rnen con ra utunt or Larta @ occons or Loao costnesurto on 109 or Lartn Q as snoen tscitos o.sc n,.
a n,. 4 e osraratornon vos.or. con aLL conotroons esct9r von racrons n coutssonless souls unen Laren@ os sonoLan ro Lartn(b on ruus cast est a
a "r *** "2 '*** " ' "-
c FIGURE 13-8 Ultirnate Load Capacity of Pile Groups in Layered Subsolls 7-13-17
.I 3
[
l
\\
l believed the i fi ei. The balanc*
The rock load H, is represented in Tfg. 27 by the rectangle ed arch. The weight d[h he w
l of the weight of the overburden is carried by the grounis transferred by t Denne sani h
The weight of the outer part acts as a surcharge on the for of t e we part c d d et the horizontal pressure exerted bY i
which tend to slide into the tunnel and increase I.oose sanc these bodies.
Sand surface
^
- i.
- :v:.,,., : q.; -. : h: f.-
The se of the earti pm on these in which w After t:
side pressu Carried by archins of H, l
H Experis I
Approx B + H, -
above the -
values det mevement j
satisfies th
__-_q minimum r the tunnel l
i I
g Carried by i H'
I i
Carried in I wedge b J f g Effect of se Carried by wedge a e e I roof support I
i If a tu
-/,
I tunnel acts k-7 l
'I
/
interstices
/
l
, I g
/
,\\
\\
l
\\
I referred to
/
H' tunnel roof
/
Direction \\of
/
through th.
rnovement during 4-4--.-
roof corre:
excavating \\
.. /
operatiocs. \\
J..
arch locate
- }
the archin
)$j',
height H, 8
.i /.
- ,.. c...iise c.
Fig. 27-I.oading of tunnel Effect of si support in sand 5 -- --* i If a tu anyin9 towards 11 The rock load H, is determined by eq. (2). According to tne text accom sand in a.
this equation, the value of the constant C depends on distance d through which the ligate the h
the materials in which the tunnel is located and on t e talled. The distance d is sustain th.
i crown of the ground arch yielded before the support was nsble means. At a given widt trated by '
not known and it can hardly be determined by practicaB i
d on the care located c) ex.
i umerical values are at a, pere with which the tunnel support is backpacked. The follow ng ndry sand. Nevertheless it l
clusively based on the results of the model tests with l
lt 62 i
L C
.L
c 4
Lateral Earth Pressures Gs P = If X l11 x-=8 w
t wlP 2
2 Comparing the above to the liquid pressure of a material of the same unit weight, we get a ratio of o.25, as liquid pressure would be 1/gwH2 This ratio is called the coeRicient K and was intro-
<--j n -->
k B
h f
i 1
i
\\
FIGURE G. APPRoxistATE BREAK 3
g p
g IN A BANK, $131PUFIED FoR cos PUTATioN g
\\g i.'
s N
,._ _1.
c W
duced by Terzaghi.1 It is an aid to rough computations of earth pressures, but in many respects is misleading, as the distribution of pressure along the face of a solid may be entirely different from that produced by a liquid. It will be noted from Figure 6 that 3
s_
l l
P, Uni / Avssure FIGl'RE 6.{. LIQUID PRESSURE
{
~har w @ m7h ON A WALL Depth y
Total pressure (P) for unit width:
P = t i n#.
f i
t e m i
i
- i.--.- >
w#
' Soil.lferhenirs in Engineering Prerfire lay Karl Tertaglil aml Ralpli Pcsk. John Wilev & Sons. Inc., egg 8, p. 3,3 l
t t
'4..-
- +.. -..