7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
1/34
Stress Analysis using 3DEC
A case Study
Dr. R. Venugopala RaoScientist & Head
Numerical Modeling
National Institute of Rock Mechanics
Kolar Gold Fields - 56 !!"
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
2/34
Stress Analysis and Design ofUG Powerhouse using
Discontinuum Modeling
Introduction
#$%ectie
'escri(tion of the )ro$lem
Geolog* and Rock Mass +lassification
+om(utational Model
Results and 'iscussion
,ack nal*sis & Su((ort .aluation
Summar* and +onclusions
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
3/34
Objective
State of stresses around the e/caations
'is(lacement distri$ution
./tent of failure 0ones
Interaction of multi(le e/caations
'esign of su((ort s*stem
.fficac* of Su((ort S*stem through ,ack
nal*sis
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
4/34
Description of the Problem
Machine Hall 206x20.4x45.5m
Transformer Hall 191x16x24mPS Manifolds 4.5x5.5m, 6x6m
Passage Dc!s ".1x"m, 4.6x5.5m
#s Dc!s 11x".5mT$T Manifolds 6.6x"m
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
5/34
Geology and oc!mass"lassi#cation
1 ranges from !234 to !2"
5 discontinuities
* Joint Sets cutting the powerhouse crown at Y=538.5 X=109.5
jset dip Aount dd !irection org "
# $ spacing eters nu
* !ip !irection with respect to %owerhouse A"is
jset dip &5 dd 11' org 109.5 538.5 &'
spacing ' nu 3
Insitu Stresses
SH !26 S
Sh !2 S
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
6/34
"omputational Model
' 'iscrete .lement Model 75/7/5
.lasto-(lastic +onstitutie Model
Mohr-+oulom$ 8oint +onstitutie Model
Su((ort S*stems
Shotcrete 9+ured )late .lement
Ri$s .:uialent liner
Rock ,olt-.lement ;ith /ial and Shear
Stiffness
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
7/34
Physico$mechanicalProperties
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
8/34
Physico$mechanicalProperties
8oint )ro(erties
Shear Stiffness JKs = 0.97 GPa/m
Normal Stiffness JKn = 10 GPa/m
Cohesion = 0.0 MPa
Friction = !
"ensile Stren#th = 0
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
9/34
%&cavation Se'uence (Support installation
Central G$llet an% si%e slashin# &ith '.!m
(ench hei#ht for )o&erho$se
*$s %$cts to (e e+ca,ate% in ! sta#es
Press$re shafts -"" manifol%s to (e
e+ca,ate% lea,in# a le%#e of !m till !00m
of P
F$ll2 #ro$te% 32&i%a# (olts of !7t
ca)acit2 &ith resin en% anchore% an% )re
tensione% to 1t
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
10/34
)ac! Analysis ( %valuationSupports
oc4 *olt Fail$re
7 (olts at %ifferent ele,ations faile% &hen
Press$re shaft manifol% 5 &as o)ene%
*ac4 anal2sis6 re,ie& of s$))ort s2stem
Ca$ses of roc4 (olt fail$re
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
11/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
12/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
13/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
14/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
15/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
16/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
17/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
18/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
19/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
20/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
21/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
22/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
23/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
24/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
25/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
26/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
27/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
28/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
29/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
30/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
31/34
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
32/34
Summary ( "onclusions
"he mo%el co$l% )re%ict the (eha,ior satisfactoril2
*olt fail$re mechanism co$l% (e e+)laine%
% The ex!en!s of roc& mass failres ha'e (een
redced )i!h !he *ro'ision of ri(s in !he cross
o*enings
% +i!h o! !he ri(s in !he cross o*enings, en!ire *illar
(e!)een !he MH and TH ca'erns exhi(i!s failre
% The *ro'ision of ri(s in !he cross o*enings ha'e
redced !he horion!al deforma!ion of !he d-s )all.
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
33/34
Summary ( "onclusions
% Maximm redc!ion of !he order 40 and 55 is o(ser'ed a!
/ /525M and / 510m res*ec!i'el
% The redc!ion in !he horion!al deforma!ions in !he -s )all is
lo)er com*ared !o !hose on !he d-s )all
% The maximm redc!ion of 40 is o(ser'ed a! / 510. The
redc!ion in deforma!ion a! /525M on !he -s )all is marginal
% The effec! of ri(s is no! seen in ser'ice (a area as !he cross
o*enings do no! exis! !here.
% The ri(s *ro'ide immedia!e and-or rigid s**or! allo)ing li!!le
deforma!ion, !here( con!rolling !he dila!ions arond !he
o*enings
7/23/2019 Discontinuum Modeling of Underground Power House Excavation - A Case Study
34/34
Summary ( "onclusions
% The exis!ing s**or! ss!em in !he machine hall )as
adea!e
% 3r!her s!reng!hening measres )ere sgges!ed as follo)s
1. "m long d)idag (ol!s in *lace of 6m long (ol!s in (s dc!s * !o10m from T
2. $i( s**or! of SM# 250 a! 50mm c-c in PS manifolds
7. $i( s**or! of SM# 150 a! 1.0m c-c in D8 from $D 20"0 and
$D 170155 in -s )all of machine hall
4. $i( s**or! of SM# 150 a! 1.0m c-c in D8 from $D 090 and
$D 125145 in d-s )all of machine hall