On-Line Risk Management
for Slopes using FOS & TRS
presentation by
K T Chang
Prof., Kumoh National Institute of Technology. South Korea
Albert Ho
Associate Director, Ove Arup & Partners Hong Kong Ltd,

Michelangelo(1475-
Michelangelo(1475-1564)

An Overview
An Overview
Introduction and background
Real-
The Real-time Monitoring System
Typical
Application
Closing Remarks

Monitoring
Speed : Cost
Safety
Quality : Current inspection techniques are subjective and
difficult to verify with audits, indicating that quality is variable
depending on the individual, circumstances.
Auditability : In an increasingly litigious society, there is a
greater need to prove that the inspection was undertaken and
to have raw data available for review by an independent party,

▶Background
● Investment: 600 Billion for last 30yrs.
● Importance of Maintenance rather than
Construction.
● Design & Construction : 85%, Maintenance:15%
● Disaster Prevention: Tremendous Savings
▶ Personal Motivation
● Uncertainties especially in the Field of
Geotechnical Eng.
● Confidence of Design, Lack of information
through the follow-ups.

Key Ideas
No Assessment, No Improvement
Daily bases- Risk management
From Signal process to information based,
Knowledge-based monitoring System
Multi-disciplinary

SLOPES on CHIP ?
PAST
PRESENT
PROSPECTIVE

Types of Sensors used
- Best use of IT links,
- Durability
- Simplicity
- Cost-effectiveness
Fiber Optic Sensor
TRS Sensor
Tiltmeter
GPS-TRS
Rain Gauge

Introduction and background:
Topographical and climatic features creating landslides
High proportion of land mass consists of mountains and hills.
- cut slopes are inevitable when constructing roads
High annual rainfall levels
Alternate process of freezing and thawing due to extreme
climatic variations

Cut Slopes - the South Korean example
Total length of national roads : 14,000km (8,750miles)
Total number of cut slopes exceeding 6m in height: 12,600
Cut slopes constructed during the 1970s∼1980s were made
with a steep slope angle which reduced construction costs,
safety not being the primary factor
Constitution of cut-slopes
Rock 79%, soil 6%, mixed materials 15%

Progress of Cut-slopes Maintenance
Run to Failure until 1994,
Preventive Maintenance since 1995
CSMS system ( D/B by experts ) since 1998,
Predictive Maintenance since 2002,
based on Real-time monitoring system ;
▶ 2002 : 4 trial sites, ▶2003 : 15 sites
▶ 2004 : 15sites, ▶ 2005 : 15 Sites
▶ 2006 : 15 Sites ▶ 2007 : 20 Sites

The Real-time Monitoring System
Real-
The TRS Sensor combines the
following:
• The tension wire sensor
• The tiltmeter sensor
The system enables measurement of
Translation, Rotation and
Settlement.``

TRS Sensors

TRS Sensors

Arrays of TRS Sensors

Vector Analysis
- Location of slip surface
using deformation kJI R
Y
vector I
kJ
K
yS =f1()
x
Suppose that one of the A x,yA)
(A
T
J'
sensors is moving downwards
BxB,yB)
(
centering around a relatively
stable point on a defined K'
kOK
section.
J(xJ,yJ)
Figure1. on the right hand Cx , y )
(C C
side shows the procedure of Figure. 1
vector analysis about how to Ox ,yO)
(O Kx ,yK)
(K
track down the failure plane
with the data acquired from
X
TRS sensors, which stands J'
O K'
for T; translation,
R; rotation, S; settlement.

Legend:
1. Drilled hole
7 2. Cement
Tension Wire Sensor
6 3. Pipe
4. Junction box
5 Installation
5. Communication cable
6. TRS sensor
4 7. Tension wire
8. Rain gauge
9. Data Logger
One of the advantages with the
3 tension wire sensor is that it
measures relatively large
2
displacements without the wire
being severed
1
9
8

Rain Gauge

Real-Time Information for Traffic Safety
Examples of Application
Navigation System

The Dangers of a Storm

Monitoring Data(March, 15 2000 ~ Sept., 2001)
2001년 6월중순경부터 응력의 변화가
급격히 증가하였는데 이 것은 2001년 월
별 강우량 집계에 나타나 있듯이 2001년
6월18, 19. 24일에 약200mm 이상의 강
우가 집중된 영향으로 보여진다. 1월부
터 6월까지는 강우량이 월 평균 수십mm
에 불과하였으며, 그 시기에 전국적인 심
한 가뭄을 겪고있었다 이러한 가뭄이 계
속되는 시기의 지반은 지반자체가 보지
하고있는 함수량이 말라버림으로서 겉보
기 점착력(Apparant cohesion)이 제거
되어 있는 상태라 할 수 있다. 이러한 지
반에 갑작스런 집중호우로 인해 포화상
태의 지반 단위중량증가로 인한 지반거
동으로 사료된다.

CATERGORISATION
RISK
&
CONSEQUENCES
OF FAILURE

Industrial development at foot of slope in South Korea

Industrial buildings in close proximity to foot of slope

Stabilising measures carried out a portion of slope

Incipient failure of the unsupported section of the slope

Failure of the unsupported section of the slope

Slope failure showing failed soil nails and shotcrete

Real-Time Monitoring for Slopes
System Schematic Real-time analysis program
현장 설치 모식도
정착지점
롤러장치
센서
Tension wire
Tension wire
Failure
인장균열 자동 강우량 센서
Rain gauge
surface
Detector
System
Site
평면 + 원호파괴
Central Maintenance Centre
Internet (ADSL)
Warning Cellular
SMS (Short Message
Service)
DB Server Web Server
Client PC

Typical on-screen Real-Time Monitoring
display for Kimhae

KNB
2600
140
2400
s4(2.5m)
2200
120
s3(8.5m)
2000
s2(11.5m)
1800 100
s1(14.5m)
1600
변형률(με)
강우량(mm) 80
1400
1200
60
1000
800
40
600
400
20
200
0 0
4/ 20 5/ 30 7/ 9 8/ 18 9/ 27 11/ 6 12/ 16 1/ 25 3/ 6 4/ 15 5/ 25 7/ 4 8/ 13
경과시간( date)
Deformation/time plot with rainfall levels for Kimhae

Predictive Models

Typical on-screen display utilising
the innovative network camera

Sensor with
warning lamp
Automatic control of traffic using
signalling system

http://www.gmgnow.kr/google_map/

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Please contact the HKIE
Geotechnical Division should you
wish to have a complete version.