Integrated Research on Earthquake Disasterof High Dams, Underground Structuresand Large-scale Cavern Groups

Prof. DU Xiuli
2016.11.19

Contents

Ⅰ. Objectives and tasks

Ⅱ. Overall research methodology
Ⅲ. Important progress and innovation
Ⅳ. Summary and prospect.

I Objectives and tasks

1. Objectives
1) Simulation of wideband strong ground motions with both high andlow frequency contents, and reproduction of seismic motions fields ofthe Wenchuan earthquake;2) Whole-process simulations of earthquake disasters of high dams,
underground structures and large-scale cavern groups;
3) Reconstruction of earthquake damages of typical key projects andreveal of their seismic damage mechanism and failure modes.

.

I Objectives and tasks

simulation ofhigh dams,
undergroundstructuresand largescale caverngroupsDevelopment ofsoftware with
proprietary
intellectual
property rights
Verification andimplementationof analyticalmodels andsoftwareNumerical platform for whole-processsimulations of earthquake disasters ofhigh dams, underground structures andlarge-scale cavern groups.

Reproduction

disaster

Basic theory
and method

Simulation of near-field ground motion
with engineering precision;
Numerical method and verification ofearthquake disasters ofcomplex systems;
Capacity-based seismic analysis method.

Integration

Earthquake

Breakthrough

2. Main research contents

Reconstruction of earthquake damagesof typical key projects and reveal of theirseismic damage mechanism and failuremodes.

.

I Objectives and tasks

3. Key scientific problems
1) Investigation of characteristics of near-filed groundmotions and simulations of broadband earthquake

motions;
2) Mechanical behaviors and constitutive models of rockand soil materials, and contact interfaces;

3) Seismic failure mechanisms of high dams,
underground structures and large-scale cavern groups;

4) Development of efficient calculation techniques insoftware for seismic simulations of earthquake
disasters.

Contents
I. Objectives and tasks
II. Overall research methodology
III. Important progress and innovation
IV. Summary and prospect.

II Overall research methodology
Seismic source rupture + Propagation of energy in a semi infinite medium 
Dynamic response of Structures

concrete arch dam

earth-rock dam

underground cavern

urban underground structureHigh Damunderground structure

震源

underground cavern

Exogenous problem: seismic input+ artificial boundary
Endogenous problem: hypocenter model+ artificial boundary.

II Overall research methodology

Strong ground motion

Independent
development(Subproject 1)

concretearch damearthrock dam(Subproject 2)(rockfill)(Subproject 3)

undergroundstructure

Opensees platform
ABAQUS

Independent
development

Independent
development
ABAQUS(concrete, rock)caverngroup(earth, concrete) ( jointed rock)(Subproject 4)(Subproject 5)

Independent
development
DDA

5 sets of special analysis software (platforms)

Contents
I. Objectives and tasks
II. Overall research methodology
III. Important progress and innovation
IV. Summary and prospect.

III Important progress and innovation

1. Seismic disaster simulation theory andmethod and system integration
2. Theory and method of broadband seismic
field simulation and implementation

3. Seismic failure mode and damage
mechanism of key structures1 Seismic disaster simulation theory and method and system integration

1.1 Numerical simulation theory and method
Structure
Material
nonlinearity

Question 1：

Artificial boundary -finite
processing of infinite
modelsContact nonlinearity

Question 2 ：The establishment of non linear mechanics model ofmaterial and contact

Question 3 ：Efficient algorithm for
nonlinear fluctuation
analysis(coupled) of large scale complex

1 Seismic disaster simulation theory and method and system integration
 Dynamic Failure Behavior and Surface Contact Model(1) Dynamic Failure Behavior Model
Plastic deformation, strain softening, cycle loading, stiffness
degradation and etc.
FailureDeformation
Mechanism

StrengththeoryDeformation
mode

Constitutivemodel(Damage) constitutive model of geotechnical materials suchas overconsolidated soil, rockfill material and concrete1 Seismic disaster simulation theory and method and system integration
Achievement 1：Proposed a nonlinear unified strength theory based on
the concept of characteristic stress.
Principal stress effect/Shear sliding surface  Shear sliding
surface/Characteristic stress  Simple and clear physical definition i 
 pa  i  pa    M     0

1 Seismic disaster simulation theory and method and system integration
Achievement 2： Established elasto-plastic (damage) constitutive modelof geo-materials for different deformation characteristics
1) Proposed an elastoplastic constitutive model of overconsolidated
soil considering strain softening and cyclic loading.
(Less parameters/5, clear physical definition, True 3D, Dilatancy properties,
Strain softening, Cyclic loading)

3-axis compression + Three-dimensional method  Direct true 3-D
elasto-plastic model  Simple, stress induced heterosexual

The Yield Surface in Characteristic Stress SpaceThe yield surface in principal stress space

1. Seismic disaster simulation theory and method and system integration
Achievement 2： Established elasto-plastic (damage) constitutive modelof geo-materials for different deformation characteristics
2) Established elasto-plastic constitutive model of rockfill considering
the particle break and dilatancy.
(Cyclic loading, particle breakage)

1
0
1
0
3
5
3
5
模型
模型
试验
模拟
8
8
3
0
3
0

q /100 kPa

q /100 kPa

6
6
2
5
2
5

4
4
2
0
2
0

2
2
1
5
1
5

0
0
1
0
1
0

εv /%

εv /%

-2
-2
5
5

0
4
0
8
4
0
0
6
试验e5
0=0.448试验e05=0.319
0
3
6
9
0
3
6
0
1
1
2
0
5
0
0
1
1
2
0
5
0
ei=0.420
σ3=300kPa 96
ei=0.445
σ3=50kPa0
ei=0.317
σ3=200kPa
04
ei=0.434
σ3=150kPa
411
ei=0.313
σ3=500kPa22
ei=0.405
σ3=500kPa22
ei=0.310
σ3=800kPa2
ei=0.381
σ3=800kPa
3
-2
0
4
4
2
0
4
6
6
6
2
8

8
8
1
0
4
0
3
6
9
0
3
6
9
0
5
1
1
2
0
5
0
0
5
1
1
2
0
5
0

εa /%

εa /%

εa /%

εa /%

1. Seismic disaster simulation theory and method and system integration
Achievement 2：The elasto-plastic (damage) constitutive model ofgeomaterials is established for different deformation characteristics
3) Established elasto-plastic damage constitutive model of concrete considering strain
softening, stiffness degradation and cyclic loading.
D

1
c
 1

1 
 1 exp    p   p0 
 D0=3.0=3.5=4.0=4.5=5.0c =0.6

Single strength criterion Generalized nonlinear strength
theory  Elasto-plastic, damage
1.2

D

0.9





0.6

0.3

0.0

0

1

2

3

4

5

6

d
p

35

1 (MPa)

28

Sinha et al. 1964
constitutive model

21
14
7
0
0.000

0.002

0.004

0.006

1

0.008

0.010

1. Seismic disaster simulation theory and method and system integration
Achievement 2：The elasto-plastic (damage) constitutive model ofgeomaterials is established for different deformation characteristics
4) Established elasto-plastic damage constitutive model of rock considering strain softening,
stiffness degradation and cyclic loading.
New model (cyclic loading, permanent deformation)
Cyclic shear test dilatancy
curve of Joint

Experimental expression of
average dilution

Relation between average
dilatancy angle
shear rate and otherphysical quantities

Ladanyi-Archambault Shearstrength model
Cycling Shear strength
model of joint

1. Seismic disaster simulation theory and method and system integration
 Dynamic Failure Behavior and Interface Contact Model(2) Interface model between soil and structureInterface element：Goodman element

Desai element

Shear stiffness？

Solution: taking usage of the relationship between the shear stress and the shear
strain on the sliding surface of the constitutive relationship of soil

Achievement 1：Based on the constitutive model of overconsolidated soil,

the contact shear stiffness model was establishedAchievement 2：Based on plasticity constitutive model of rockfill material,
the model of interface contact shear stiffness was established1. Seismic disaster simulation theory and method and system integration
 Artificial Boundary and Input of Ground Motion(1) Artificial Boundary
Major achievements of international studies in the last 4 decades---- Displacement Artificial Boundary Condition
0.3

旁轴边界
0.2

Displacement

Wave equation

u 1 u0x c tExact
2nd-order transmitting formula
1st-order transmitting formula无限远场
外推的差分格式

Near field

0.1

u xt  F (u xt 1 , u xt 12 ,)0.0

Common law

u  f ( x  ct )

-0.1
透射边界
0
4

8

12

16

20

Time

Artificial boundary①

Low-frequency drift and high-frequency oscillation instability phenomenon② Inconvenience in the commercial finite element software1. Seismic disaster simulation theory and method and system integration
 Artificial Boundary and Input of Ground Motion(1) Artificial Boundary
Important development direction ---- High Order Precision Stress Artificial Boundary Condition
u1 (t )u (t )C1 M1 C2 M 2
C0InfiniteK
far field

0

Near fieldu2 (t )u N (t )CN M N力
Equivalent学
mechanical系
system统

Artificial Boundary①

The equivalent mechanical system is consistent with the finite element equation② To avoid low-frequency drift and high-frequency oscillation instability

1. Seismic disaster simulation theory and method and system integration
Achievement 1：A Systematic Method for Constructing High - Precision Time
Domain Artificial boundary is proposed
Boundary force-Displacement
relationship(Frequency domain)

Force-displacement
relationship Approach to the

Stability of a High Order Linear
SystemS ( ) 

p0  p1i  ...  pN 1 (i )q0  q1i  ...  qN (i ) N

N 1

S j  g j  ih j  iS j 11

f (t )

K0

C1

C0
M1
C2

M2

(reduced order) Time - domainstate space system

S( )  g 0  ih 0  iS11
j  1, , N
Continuous fraction

Rational function

equivalence
Containing internal variables

Vector F ( )  S( )u( )Scalar F ()  S ()U ()u (t )
u1 (t )

u 2 (t )CNMN

u N (t )

Cbb

Ccb

Cbc  u  K bb
  Ccc  u   K cb

K bc  u  f    
K cc  u  0 

1. Seismic disaster simulation theory and method and system integration

Achievement 2 ： Established high-order time-domain artificial boundary
conditions for several classes of problems
 Wave propagation problem
 Exterior problem
 Cylindrical and spherical elastic wave radiation
 …
Achievement 3：Low order stress type artificial boundary-viscoelastic artificial
boundary condition(Single-phase and liquid-solid coupling saturated two–phase materials)

Undergroundstructure
Soil
Rigid foundation

gravitydam

Water

1. Seismic disaster simulation theory and method and system integration
 Artificial Boundary and Input of Ground Motion(2) Ground motion input
Results: established seismic oblique incidence input method forstratified half-space field

Algorithm to achieve:
BottomBoundary
Conditionφ

Calculation modelWith results：

y
o
θ z'

x
x'
z

Snell
law

Finiteelement
method1. Seismic disaster simulation theory and method and system integration
 Efficient and high precision numerical method(1) Efficient algorithm—Space - time Localization Method
 Based on the concept of finite velocity, the current time response of a node is only related to
the reaction of the first few moments of the neighboring nodes.

 It is not necessary to solve the coupled equations, and the computational efficiency is high,saving memory and being suitable for parallel computation.

Time step
number

n+1
n

m-1

m

m+1

m+2

m+3

node numbera) Differential equation--Finite difference Space-time decouplingb) Integral equation--Finite element method Necessary Conditionsfor Space - Time Decoupling Time domain difference Centralized
quality model1. Seismic disaster simulation theory and method and system integration
 Efficient and high precision numerical method
Achievement 1：The explicit finite element method of viscoelastic solid medium of D'Alembert was developed
Achievement 2：The explicit finite element method of saturated two-phase media is developed
Achievement 3：An explicit algorithm for the dynamic contact force and the dynamic contact force of thesolid medium is establisheduk 1  M 1  fuk  Kd  uk  Q  pk   t 2  2  uk  uk 1

Quality matrix M
Fluid compression matrix S

t n
 t

 t

pk 1  T  pk   i  T  1   i    S 1  f q tk  1   i 
2 i 12
2
Using a unified diagonal processingS 1QT T  1t  S 1QT
TS 1QT 
u  tk 1  
u  tk  
u  tk 1 
2  t
t
t


1.0

-0.4

孔压/Pa

A

-0.2
位移/×10-3m一致质量和流体压缩矩阵
集中质量和流体压缩矩阵

1.2

0.0

B

-0.6

C

0.8
0.6

A

0.4

-0.8

B

一致质量和流体压缩矩阵
集中质量和流体压缩矩阵

-1.0

0.2

C

0.0

0

5

10

15

20

25

时间/s

30

0

5

10

15

20

25 30
时间/s

1. Seismic disaster simulation theory and method and system integration
 Efficient and high precision numerical method(1) Efficient algorithm—Elastic - Plastic Stress Updating Algorithm
Existing stress update algorithm：Elastoplastic iteration (Increment)+Nonlinear
iteration high calculation cost, low precision
Proposed stress updating algorithm: loading and unloading judgment+Nonlinear
iteration Small calculation amount, high precision

Strain hardening + Strain softening=Judged by the over-consolidation ratio

Suitable for large-scale computing
1.0
0.8

R

0.6
0.4
0.2
0.0
0.0

3- Dimensional Elastic - Plastic Model of Lower Loading Surface

Elastic - Plastic Stress Updating Algorithm

0.5

1.0

1.5



2.0

2.5

3.0

Loading and unloading guidelines

1. Seismic disaster simulation theory and method and system integration
 Efficient and high precision numerical method(2) Grid Dependency—Strain softening, cracking and stressconcentration etc.
Achievement ：Apply extended finite element model and thickness-freebonding element model to the analysis of high dam

1. Seismic disaster simulation theory and method and system integration
 Efficient and high precision numerical method(3) Discontinuous deformation problem
DDA, Discrete element and Manifold etc.
Achievement ：Apply DDA and discrete element method to seismic
hazard analysis of high dam and underground cavern1. Seismic disaster simulation theory and method and system integration

1.2 Physical Simulation Theory and Methodology
defect：Uniform similarity can
not be satisfied

defect：Small size and Coriolis
effect1-G

N-G

advantage：Physical Modeling ofLarge - Scale Target Structures

advantage：meet the stresssimilar

1、semi qualitative - quantitative analysis。

2、Validation of mature numerical algorithms，to provide
technology support for the simulation sets.

1. Seismic disaster simulation theory and method and system integration

1.2 Physical Simulation Theory and Methodology

Local stressconcentration andproperties of concretematerials

Stress Distribution andDamage Cracking
Process in Dam Body
sub-project 2：concrete dam

panel suspended andbended, interior wall
bended during shaking

Similarity of dam breaking process and its
macroscopic
phenomena

sub-project 3：Panel dam,
Earth - rock dam
Underground structure
controlled by thesurrounding soil
displacement

Development of Soil Box
Simulation of free shear
properties of soil layers
sub-project 4 ：Undergroundstructure

Stability of surroundingrock and relative sip ofsurrounding rock blocks

Development of model soilbox and accurate
simulation of surroundingrock material
sub-project 5 ：Underground1. Seismic disaster simulation theory and method and system integration

刚性模型土箱叠层剪切型模型土箱悬挂式层状多向剪切箱
小尺寸材料
光纤光栅应变测试技术

可控连续体模型土箱

Subproject 4

98通道数据采集系统

数据批处理平台Subproject 4

Data collection system

Subproject 2

非接触性动态位移测试平台

Real-time video
monitoring system

Subproject 3

1. Seismic disaster simulation theory and method and system integration

Subproject 2

Water ：cement：lime：sand＝0.5:1:0.58:5

Subproject 5: new materials forunderground cavern

Plaster, Barite powder, Quartz sand, water and Gypsum retarder1. Seismic disaster simulation theory and method and system integration

0
01
1

A small-scale centrifugal model test method by stress approximation(N-G)

Numerical simulation
A similar method with good feasibility is
obtained by extension analysis by sub project 30021Model similarity ratio design

Similarity design method of multi-medium coupling soil-structure system（1-G）
Soil

Multi-medium
coupling tests ofsoil-undergroundstructure system

similarity ratio
design of soil
Objectives

Undergroundstructures

Structuralsimilarity ratio
designDynamic
characteristics ofeach medium

Similarity
ratio designof system

The soil-structure similarity ratio design problem could base on the dynamic
characteristics of the foundation soil by Subproject 2

1. Seismic disaster simulation theory and method and system integration

1.3 System integration① Developed a software platform for seismic time history synthesis andseismic field simulation② Developed a high concrete dam seismic analysis software③ Improve and develop the high earth and rock dam seismic simulation
software platform (GEODYNA6.0)④ Developed a large-scale underground structure earthquake simulation
software (GDA)⑤ Developed a large-scale underground caverns earthquake simulation
software1. Seismic disaster simulation theory and method and system integration

Ground motion synthesis andseismic dynamic field simulation
integration platform

Achievement 1: Seismic Ground Motion Synthesis and Seismic
Field Simulation Platform

Strongvibration
database andcharacteristic
analysis
platform

Artificial
groundmotion time
history
synthesis
platform

Multi-parameterground motion record
query
Real-time display ofanalysis results
Time history synthesisof ground motion withrandom phase method

随机相位法地震动时程合成？
Theoretical method ofseismology

Seismic
dynamic
simulation
platform

Empirical statisticalmethodWide band synthesis
method1. Seismic disaster simulation theory and method and system integration
Achievement 2: high concrete dam seismic analysis software

The analysis software of earthquake disaster of high concrete dam isdeveloped and verified by the model test and the actual earthquake
damage based on ABAQUS and OpenSees.

Basic function
Infinite foundation
radiation damping
Dam-water interaction
Energy dissipation in
upper reaches of reservoir
Nonlinearity of dam
material
Nonlinearity of transverse
joints of dam

Seismic reinforcement
measures of dam

Code uploaded to
OpenSees website

1. Seismic disaster simulation theory and method and system integration
Achievement 3: High earth and rock dam seismic simulation software platform(GEODYNA6.0)

 High development
efficiency
 Easy transplant andmaintenance ●●●object-oriented
programming Seismic wave
 Hydrostatic
12 types ofpressure Nodeloadings
change ●●●High performance andlarge scale computing

3-D nonlinear
static and dynamic
finite element
analysis
GEODYNA6.0

9 types ofanalyses Block element
28 elements
 Interface
14 constitutive
Integration of seismic
element
modelsdisaster simulation methods
 Coupling Complex seismic motion input
element
 Fluid-solid coupling of dam and water Beam element
 Damage and crack of concrete
 ●●●
 ●●●

 64 bits
 multithreading multi-coreparallelprocess
 GPU
acceleration

 Dynamic
 Consolida
tion Static ●●● Generalized
plasticity
 Plastic
damage Equivalentlinear statedependent;
 ●●●The calculation scale breaks through 50 million degrees of freedom (static problems) and 10
million degrees of freedom (dynamic problems), is able to solve large-scale, non-linear andearthquake-destroying calculation problems of the 300-meter high earth-rock dams.

1. Seismic disaster simulation theory and method and system integration
Achievement 3 : Large-scale underground structure earthquake simulation
software (GDA)
Geotechnical Dynamic Analysis(GDA) program
Complete
independent
developmentofGDA
effectively
handledthetechnical difficulties e.g. highcomputational costs and highnonlinearity
duringthenonlinear dynamic analyses ofunderground structures.

稳定步长

GDA has the characteristics of
highscalability,
easeofdevelopmentofnewalgorithms
andmodels,providing excellent software
platform for the integration ofresearch achievements.

Fine and efficient nonlinear finite element analysis ofunderground structures and software platform for research1. Seismic disaster simulation theory and method and system integration
Achievement 5 : Developed a large-scale underground caverns
earthquake simulation software

Local and overall combination of efficient, fast, multi-level seismic response and disaster simulation
platform

1. Seismic disaster simulation theory and method and system integration

Statistical characteristics ofground motions（Time frequency nonstationarity）

Empirical method

Attenuation
law analysis

Site groundmotion synthesis

Local site condition crustal
structure model

Analysis of
Seismic Wave
Propagation

Numerical
simulation of near- field groundmotions

Earthquake Source model（Local parameters）

Theoretical methods

Seismic field
simulation
method.

IV Summary and prospect
1. Study on the theories and methods of earthquake disaster simulation.
2. Several progress on physical model tests and a series of destructive
tests in this research.
3. New recognitions on the seismic damage mechanism and failure modes.

Acknowledgement

Thanks！