We are stabilising an ubstable slope by installing bored piles which is 
already excavated till EL 248.00m. level as per the drawing enclosed, 
Geology and the history of the failure of the slope is enclosed for your 
sake of convinence,
 
I am giving some considerations of the analysis that may be to help of 
you, the rock mainly composes of C.shale layer, though some bands of 
sandstone have been observed. Our designers opted to consider the total 
layer as C>shale with properties as E = 900 MPa, Poission's ratio= 0.25, 
cohesion= 0.10 MPa, friction = 35 degrees. Intially the slope has been 
excavated till EL 253.00m. with 1.5(V):1(H) with minor supports that 
failed with lots of cracks and flow of material.
 
Now our designers have modified the slope as mentioned in the drawing, so 
the sequence is to install pile at EL 248.00m. berm and again excavate 
till EL 237.00m. berm and install the bored pile. Now the rest material 
will be excavated and find that target FOS is greater than 1.40.
 
The piles are of 1.00m. diameter at 5m c/c spacing, I am confused on 
selection of Normal stiffness, cohesion and friction values. I found from 
the mannual that in my case the normal part of stiffness rather than shear 
part will play the major role.
 
I am not getting the benefits of installing piles, please help me to show 
the correct behaviour of rock-pile interaction,
 
Regards,
 
Debasis 



;Kameng Powerhouse Slope
config ats
grid 30,20 *600 zones
mod mohr
pr mem *
gen -89.043,-89.043 -89.043,89.043 164.9062,89.043 164.9062,-89.043
; Add top surface
table 1 10.0,89.043 30.0,79.043 33.0,79.043 53.0,69.043 58.0,69.043 60.5,64.043
*print table 1
table 1 63.5,64.043 66.0,59.043 68.0,59.043 73.0,54.043 75.0,54.043 80.0,49.043
*print table 1
table 1 87.0,49.043 89.5,44.043 92.9,44.043 95.9,38.043 102.9,38.043 106.4,31.043
*print table 1
table 1 108.4,31.043 112.0,23.843 122.0,15.843 151.3,15.843 152.2,20.343
*print table 1
table 1 164.9062,24.7026
gen table 1
mark i=31 j=13
mark i=20 j=18
mark i=21 j=18
mark i=22 j=18
mark i=23 j=18
mark i=24 j=18
mark i=25 j=18
mark i=26 j=18
mark i=27 j=18
mark i=28 j=18
mark i=29 j=18
mark i=30 j=18
mark i=31 j=18
;
fix x y j=1
fix x i=1
fix x i=31
;consolidation under dry unit weight *4367559.15
ini syy=-4367559.15 var=0,4367559.15
ini sxx=-4367559.15 var=0,4367559.15
ini szz=-4367559.15 var=0,4367559.15
prop density=2500.0 bulk=1E9 shear=3E8 cohesion=1e50 friction=35.0 dilation=0.0 tension=1e50
;
set gravity=9.81
hi 1 unbal
hi 2 xd i=24 j=13 *top right of model
solve 
ini xd=0 yd=0
; Add water table
table 2 (-89.043,85.0) (0.0 73.0) (9.4506 72.3305) (18.866 71.2526)
table 2 (28.0384 69.0491) (37.0358 66.0895) (45.3896 61.6151)
table 2 (54.1206 57.9717) (63.2888 55.5725) (72.2484 52.5176)
table 2 (80.9202 48.7554) (89.3793 44.5637) (97.0 38.0)
table 2 (106.0 31.0) (111.0 25.0) (122.0 16.0) (151.0 16.0)
table 2 (164.9062 16.0)
def wet den
	loop i (1,izones)
		loop j (1,jzones)
			if model(i,j)>1 then
				xa=(x(i,j)+x(i+1,j)+x(i+1,j+1)+x(i,j+1))
				xc=0.25*xa
				ya=(y(i,j)+y(i+1,j)+y(i+1,j+1)+y(i,j+1))
				yc=0.25*ya
					if yc < table(2,xc) then
					density(i,j) = 2700
					endif
			endif
		endloop
	endloop
end
wet den
water density=1000.0
water table=2
plot hold grid water yel
solve
ini xd=0 yd=0
prop cohesion=100000.0 tension=10000.0 reg=1,1
solve
ini xd=0 yd=0
mod null reg 30,20 *Excavate the bench at EL 248.00m.
plot hold grid mark displ max 0.10
save temp11.sav
;
restore temp11.sav
ini xd=0 yd=0
;*** Branch: Pile-supported at EL 248.00****
struct pile begin 83.00 49.0430 end 83.00 14.0430 seg 10 prop 3001
struct prop 3001
struct prop 3001 e 8.0e10 radius 0.50 perimeter 3.140
struct prop 3001 cs_ncoh 1.0e08 cs_nfric 35 cs_nstiff 3.0e11
struct prop 3001 cs_scoh 1.0e10 cs_sstiff 1.3e11 cs_sfric 35 spacing 5.00
plot hold grid struc pile yel mark water yel
solve
plot hold grid mark displ max 0.10
save temp12.sav
;
restore temp12.sav
ini xd=0 yd=0
mark i=23 j=15
mark i=24 j=15
mark i=25 j=15
mark i=26 j=15
mark i=27 j=15
mark i=28 j=15
mark i=29 j=15
mark i=30 j=15
mark i=31 j=15
pl hold grid mark fix
mod null reg 30,16 *Excavate the bench at EL 237.00m.
plot hold grid mark fix
solve
plot hold grid mark displ max 0.10
save temp13.sav
;
restore temp13.sav
ini xd=0 yd=0
;*** Branch: Pile-supported at EL 237.00****
struct pile begin 99.90 38.0430 end 99.90 13.0430 seg 10 prop 3001
struct prop 3001
struct prop 3001 e 8.0e10 radius 0.50 perimeter 3.140
struct prop 3001 cs_ncoh 1.0e08 cs_nfric 0 cs_nstiff 3.0e11
struct prop 3001 cs_scoh 1.0e10 cs_sstiff 1.3e11 cs_sfric 0 spacing 5.00
plot hold grid struc pile yel mark water yel
solve
plot hold grid mark displ max 0.10
save temp14.sav
;
res temp14.sav
ini xd=0 yd=0
mod null reg 30,14 *Excavate the rest material
solve
plot hold grid mark displ max 0.10
save temp15.sav
;... State:fos.fsv ....
solve fos include struc
save temp16.sav
pause