Geotechnical & Structural Automated Real Time Monitoring and Alert Systems

Geotechnical & Structural

Automated Real Time

Monitoring and Alert

Systems

Institute of Engineers, Singapore 17th October 2007

Dr G H Tan, SysEng (S) Pte Ltd

Poh Y K, SysEng (S) Pte Ltd

Nick Osborne, Land Transport Authority

Albert Chua, Lee Hung Test Services Pte Ltd

William Tang, DKSH

Seminar Schedules

0900-1000 Real Time Monitoring &Alert

System Overview

1000-1030 Break

1100-1200 Data Loggers,Communication

,Power Supply, Protection,

Data Quality, Accuracy

1200-1330 Lunch

1300-1500 User perspective, Planning

&Operation

1530-1700 Proven Sensors

Straits Times March 24th 2007

`

• SysEng is a System

Engineering Company with

Multi-disciplinary Engineering

Capabilities

• Started in 1994 by Engineers

• To deliver the Right Data , at

the Right Time, at the Right

Place with the Right Price

and the Right Quality to

make the Right Decision

• Vertical Integration as a

One-Stop Shop Engineering

Solution Service to ease the

deployment and support of

complex technologies to

help in the growth of the

client’s business

An Automatic Real Time Monitoring & Alert System to help

Professional Engineers, Consultants and Authorities

monitor Geotechnical and Structural movements 24 x7

without any human effort.

The Benefits are :-

• Equipments & System are leased to clients without Fixed

Overheads, Engineering Team and Investments.

• Pays for Timely, Quality and Reliable data.

• No Hidden Repair and Support costs.

• One time setup fee and monthly monitoring fee to help your

cash flow.

• Leverage on SysEng Engineering Expertise in Sensors,

Electronics, Communication, Software, EMI Noise Prevention &

troubleshooting to support the clients.

• Technical Service Support with 24 Hours Alarm Monitoring

Excavation Works in SingaporeArea of Singapore 700 km2

Area of excavation 250 000 m2 (more than 50% excavation > 20m deep)

Excavation Works in Close Proximity to Buildings

What is Real Time

Monitoring & Alert

System ?

What is actual Real Time ?

• Is it continuous monitoring ? Then what is

continuous then ?

• Is it Real Time Data logging only ? Data

Logging is ONLY one basic component for

Real Time Monitoring and Alert system

• If characteristics move in days, then

monitoring every hour is real time ?

• If characteristics move in hours, then

monitoring every minute is real time ?

Widely used CR10X

Data Loggers & and

Data Logger

Software used in

Singapore , but

these by

themselves are NOT

Real Time

Monitoring & Alert

system

For Continental

Drifts of 50

million years,

Real Time

Duration in this

context is

actually 1

million years

In a Car Crash

of 1/1000 of a

second event,

Real Time

Duration in this

context is

actually

1/100,000 of a

second

This Can Happen in 24 hours ! As reported

in the Front Page of Straits Times

Glassgow Road Sumitomo

Tunnelling Affects Roads

In 2003, BCA had to 3

runs on “Avoiding

Failures in Excavation

Works” seminars to

help the Construction

Industry so that

• Lives can be saved

• Assets can be

protected

• Reputation can be

maintained

20 April 2004

How could it occur at your site if you use

real time monitoring ? It is better to use a

professional service to protect lives and

your reputation

Korean

Bridge

Collapse

• Seoul, South Korea

• 8AM October 21, 1994

• 1160m truss bridge

• 32 people killed, 20 injured

• Constructed in 1979

• Cause: structural fatigue

• Monitoring is now

mandatory in South Korea

REPAIR, REPLACE, UPGRADE, MAINTAIN

~600,000 bridges in the USA, investment ~$212:

US$20,000,000,000 on bridge repairs in 6 years

In Geotechnical and Structural Real Time

Monitoring & Alert System, these soil and

building movements tend to be man-made.

If there is no excavation works around that

area. Real Time Monitoring & Alert can be

considered to be every hour or even less

frequent. Usually this sufficient for Design

Verification where is enough time to react.

However, if there are continuous excavation

works adjacent with de-watering, jet grouting,

then Real Time Monitoring & Alert is then in

Minutes as there is a need to respond to the

unexpected change in the conditions

What is expected of a Real Time Monitoring & Alert System?

Doctor tells the Nurse:

“Please monitor the patient

and call me immediately if

there is any change in his

condition.”

Hospital = Construction Site

Patient = Excavation works

Doctor = Consultant

Nurse = Instrumentation Specialist

Call Immediately = Real Time Monitoring of 10min

Real Time Monitoring & Alert requires Real Time Responses

• This is achieved with

Real Time Sensor Measurement,

Real Time Data Logging,

Real Time Data Processing,

Real Time Analysis,

Real Time Alert to be sent to the Right Person

Important is the organization to react to this Alert

If any part of the information flow chain fails, then the entire system fails

It is NOT a solution as the site problem needs a specialist

diagnostic and hence specific solution to the

problem

Real Time Sensor Measurement

Real Time Data Logging

Real Time Data Processing

Real Time Analysis

Real Time Alert to be sent to the Right Person

Important is the organization to react to this Alert

Sensors Data Logger Communication Analysis Alert

There are many ways to configure

Data Loggers into a Real Time

Monitoring & Alert Systems with

various method of Communications or

Telemetry

Communications

Communications Options

All on site data must be brought back to a

PC for Analysis

More common in Singapore

GSM Data

More common in Singapore

Lessons about a Real Time

Monitoring & Alert System

Statements stated in the

Nicoll Highway Inquiry

Nicoll Highway Court of Inquiry has taught us a valuable lesson that

having data in the instrument and then getting information only after

24 hours is NOT Real time. The system can fail with 999 readings

and NOBODY is even aware of such systematic failures !

Three Points highlighted in by the

inquiry

1. The Real Time System used is an

in-correct Real Time System

2. If sensor is not working with “999”

readings and nobody is alert about this

error

3. Alerts are send via email only once a

day

This was the system Deployed for Real Time Monitoring &

Alert System is Actual Only Real Time Data Logging !

Upload 0000 hrs

Email Alert

only @

0000 hrs !

next day

Walers buckle More Walers buckle

Some Real Time Monitoring Systems are

defined from the moment when the data is

available at the server. These systems do

not take into account the delay in getting

the sensor data to the server

Sensor data

collected on sites

can have hours to

days delay before

they are send to

the server

Real Time Monitoring &

Alert System is the

time when the sensor

data is collected till

when it reaches the

end users

Real Time Monitoring

& Alert is

Analyzing the data

immediately into

information for the

user to take informed

decision

Real Time Monitoring & Alert

• Systematic data management is required to

avoid information overload and condense

huge information into information the human

user can handle

• Simplify the human interface for easy

interpretation and de-skilling of decision

operations

• Real Time Continuous Monitoring by

Computers need the same corresponding

Real Time Continuous Analysis by computers

also !

Real Time Monitoring System

gives SMS Alerts within 10

minutes,hence earlier reaction

time for crisis management

SMS Alert

Challenges

in Operating and

Maintaining Systems

System Design Steps for a

Remote Monitoring System

•Objective of Monitoring

•Approach to fulfill Objective

•Implementation of Approach

•Constraints of Approach

•Verifying Approach and

Constraints

Objective of Monitoring

•Who wants the results ?

•Is it to verify the Design ?

•Is it to check the

Construction Quality?

Approach to fulfill Objective

•What sensors to use ?

•Accuracy of sensors w.r.t.

System accuracy ?

•Environmental Protection ?

•Power & Communication

availability ?

•Data Storage on site ?

Implementation of Approach

•Cost effectiveness of signal

flow chain ?

•Accuracy of System ?

•Site condition ?

•Cost of Communication ?

•System&Component support ?

•On site support ?

Typical Dangerous Answer

to be careful :

•I want everything but forgot to

ask how much it will cost

•No Cost Limit (To his

customer or to you ?)

•I want the best only but forgot

to mention price constraints

The infamous

Dr Frankeinstein use

the Best of Everything

to create a Monster who is

made from parts from

different suppliers. A system

has to consider the working

strength and weakness of

all parts

Solutions to some of

the Challenges

Design Parameters for

Remote Monitoring System

•Sensors selection and location

•Transmitting results from sensor to

central data logger

•Amount of data measurement and

data transmission

•Noisy

•Signal degradation from sensor

to signal conditioner

Quality & Reliability

of

Sensor Data

Sensor

Signal

Conditioner

Data

Logger

High Electro Magnetic

Interference or Unwanted signal

sources from Motors, Arc

welding Equipment, Heaters,

Inverters, etc

Digital Signal

with 1.1 valueAnalogue

Signals

Use of a Fast Fourier

Transform (FFT)

Spectrum Analyzer to

check the Signal to

Noise Ratio to verify

Quality of Signal

presented to the ADC

Readout gives 1.1value

= 1.05(Sensor) + 0.05(Noise)?

= 0.9 (Sensor) + 0.2 (Noise) ?

= 0.5 (Sensor) + 0.6 (Noise) ?

When the actual signals coming into the

input, checking the signal inputs to the

data logger is important as the signal

has high noise, but the data logger has

a simple RC network, the signal still

goes through and the waveform

measured is no longer the true level but

a signal which is reconstructed due to

aliasing

This is a well

known

measurement

Error !

The Data will show No Change in readings !

Actual Movements

If measuring a cyclic change, it is better to measure faster and then

reduce the rate after the characteristics are known, a faster change is

when measured at slower rate give WRONG information !

Knowing the Critical

Bottleneck in Data

Quality and Accuracy

70dB Sensor 60 dB 90 dB Signal 50 dB 16 Bit ADC

Wiring Conditioner Wiring Data Logger

In the whole signal flow from sensor to the Data

Logger, the weakest part is only 50 dB !

Signal to Noise Ratio in the Data Flow Chain

Real Time Monitoring needs

Data Management &

Data Visualization

Instrument readings in chart form

Average Axial Force in Level 3 Strut 21-A

-200

0

200

400

600

800

1000

1200

1400

1600

09-Jan

10-Jan

11-Jan

12-Jan

13-Jan

14-Jan

15-Jan

16-Jan

17-Jan

18-Jan

19-Jan

20-Jan

21-Jan

22-Jan

23-Jan

24-Jan

25-Jan

26-Jan

27-Jan

28-Jan

29-Jan

Date

Force (

kN

)

S21-3-A Trigger S21-3-B

Case History for Temporary Struts Automated Monitoring

A Geotechnical

Real Time

Monitoring &

Alert System

IDA featured

SysEng in

their

Website as a

Recognition

of our

contribution

towards

M2M

In the International Workshop of

ITU, this paper showcased the

Advance Wire-less application

deployments in Singapore.

SysEng M2M Real Time

Monitoring System was

described in this prestigious

workshop

SysEng M2M application in

Construction site Temporary

Strut Force Real Time

Monitoring & Alert System

Mar 2004 - “Real Time Monitoring Systems in Tunnel & Deep Excavation Projects” at

Geotechnical Conference, Malaysia

Aug 2004 - “Real Time Monitoring and Alert Systems for Civil Engineering applications

using Machine-to-Machine Technologies” at International Conference on Structural

and Foundation Failures, Singapore

Jan 2005 - “Evolution of Remote Structural Health Monitoring Systems with M2M

Technologies” at Society of Experimental Mechanics, IMAC XXII Florida, USA.

Oct 2005 - “Ubiquitous Real Time Monitoring and Alert applied to Excavation Works” at

4th International Symposium on New Technologies for Urban Safety of Mega

Cities in Asia, Nanyang Technological University, Singapore

Nov 2005 - “Real Time Monitoring and Alert in Excavation Works using Machine to

Machine (M2M) Technologies” at 2nd International Conference on Structural

Health Monitoring of Intelligent Infrastructure, Shenzhen, China

Mar 2006 - Improving Instrument Data Quality from Excavation sites to the Right

person to make the Right Decision at the Right Time, International Conference and

Exhibition on Tunneling and Trench less Technology, Malaysia

Apr 2006 - Conference Paper Automatic Real Time Monitoring using M2M Technology”

in Seminar on Instrumentation Monitoring for Underground and Tunneling

Construction Safety in Chengdu Railway Co. Ltd and Southwest Research Institute

of China Railway Engineering, Chengdu China

Real Time & Alert System presented in

numerous Civil Engineering Conferences

In the New Down Town Line Real Time & Alert Monitoring System Specifications

In the New Down Town Line Data Quality & Reliability Requirements

In the New Down Town Line Data Quality & Reliability Requirements

The eMonitoring Real Time Monitoring & Alert System has

many Smart Technologies to detect various fault conditions to

ensure that the entire system has Higher Service Uptime.

The Smart Technologies detect when:-

•Individual sensor cable faults of open or short circuits

•Data Logger Backup Battery Health status

•Data Logger cannot send sensor data to the Central

Monitoring System (CMS) for processing as well as its sub-

systems

•Wire-less GPRS and Internet Data Communication not

available

It automatically monitors the entire system every 60 seconds

and alerts SysEng support staff to correct the situation in a

proactive way. This makes it more reliable than human-

supervised monitoring system.

The System automatically sends SMS Alerts when sensor cables are cut,

VWSG Cables cut

SMS Alert

automatically

pushed to all

users

The System automatically sends them SMS Alerts when :-

On-site RTU/Data Logger

has not send Sensor

data to the on-line

Central Server System

On-site RTU/Data Logger

Backup Battery Voltage

falls below 11.0V

SMS Alert

VWSG Sensor reading

has exceeded its Alarm

Limit

Case History of Real-time Monitoring

and Alert System Deployed in C821

• 92 VW Strain gages and 5 VW load cells (with 4 VW sensors per load cell) are monitored every 10 minutes.

• Monitoring frequency every 10 minutes with 112 x 6 x 24

(= 16,128) Readings per day !

• The results were sent to secured web-site every 10 minutes.

• SMS alert to contractor and consultants when measured strut force exceeding 70% of design value

Solar Powered

Monitoring CR10X

Data Logger

Case History for Real Time Monitoring System

VW Load Cell

Case History for Real Time eMonitoring System

SMS Alert

A Structural

Real Time

Monitoring &

Alert System

Real Time Tunnel Structure

Deformation Monitoring system

In Business Times

23th March 2003,

SysEng was

featured at the

center page by

IDA as a State of

the Art Wire-less

Technology

System Developer

for Automatic

Tunnel Monitoring

System. This is the

innovative method

of deploying Wire-

less and

Inforcomm

Technologies for

Tunnel Monitoring

• LTA code of practice allows less than 15mm

movements along the segments

• Tunnel distortion allowable is 1/2000

• Continuously monitors the prisms every 8

hours per day for 7 days a week

• Reliable System up time with financial penalty

imposed for delay or loss of data

• Real time measurement and immediate data

transmission of results

• Immediate alerts if the movement exceeds

70% of allowable movement

Typical Set-up of Automated Tunnel

Monitoring System

Glass prism as reflectors

Range 20 to 100m

Accuracy +/- 1.0mm + 1ppm

Semi-automated system with manual data retrieval and manual alert system

Fully automated system with automatic data retrieval and SMS alert system

Automatic Information push

Manual Information pull

Tunnel Monitoring Timing Chart of sensor readings till end user

SMS alert

Time for one Measurement cycle

50 mins

50 prisms Tx Data

2 mins

Analyze

1 min

SMS Alert

2 mins

A Total of 55 mins per Measurement cycle with the

longest time taken by Prism measurements

At 3 Measurement cycles per day

00:00 08:00 16:00

GSM

• With 1 prism , X,Y,Z movements (3 points) are measured

• In one segment, there are 4 prisms.

Hence 12 data points per segment

• With 500 rings, there are 6,000

points per measurement cycle

• One day there is 3 measurement

cycles

• Hence one day the user is overload

with 18,000 data points to analyze !

With Real time system and more

data collected, end user gets

information overload !

Smart SMS Alert System

Remote Monitoring

System in a High Rise

Tower Block during

Construction Phase in

Hong Kong

Design Requirements

·Continuous monitoring of Displacement

and Strain gages to monitor the load

·Duplicate Strain gage sets

·Continuous data transmission to the

central data logger

·Smart Event driven data storage rather

than continuous logging

·Different threshold for alarming using

GSM/SMS and Paging

Construction

Phases of a 420 m

High Tower Block in

the Region

Configuration

Level 33

RS485

Network

Level 53

RS485

Network

Level 65

RS485

Network

2.4 GHz

Highway

Central Data

Logging Station

SMS Alert

System

Construction at

Stage 1 of the

420 m Tower

BlockLevel 33

• 18 Strain Gages and 1 temperature sensors are mounted onto the bridge

• The data is logged every 10 minutes and send back to a website for

computation for sensor calibration into

• Real time is used so that the effect of strain changes during the post

tensioning can be tracked continuously

Real Time System for Highway Bridge

Widening Post Tensioning at KJE

Real Time Strain monitoring at 10 minutes

intervals during the post tensioning phase

Pasir Panjang Semi-Expressway

Balanced pre-cast cantilever construction

5 spans instrumented with VWGs

LTA Pasir

Panjang C3223

Bridge

Instrumentatio

n at Kicker,

Column and

Box Girdle

Tuas Second Link

VW strain

gauge

VW stress

cell

Instrumentation for Monitoring (1997)

Three segments of one span instrumented with a total of:

• 12 strain gauges

• 12 stress cells

• 40 temperature sensors

7 equal bays

@ 4000 each

232731

13 245678910111232 131416 151718192021222325 24262728293031333536373839404143 4244 34

MALAYSIA

SINGAPORE

3 equal bays

@ 3200 each148007 equal bays

@ 4000 each

3 equal span

@ 3200 each148007 equal span

@ 4000 each

3 equal bays

@ 3200 each

2000

closure segment

40m 92m

6 equal bays

@ 4000 each

3 equal bays

@ 3200 each

48m

Location of instruments

in span segments: top 23/31, below: 27

SG3 SG1

SG2 SG4

SG3,PC3SG1,PC1

SG2,PC2

T11T12T13T14T15T16T17T18T19T20

T1T2T3T4T5T6T7T8T9T10

SG4,PC4

VWT1 VWT2

VWT-Temperature sensor.

T-Thermocouple

SG-Strain gauge

PC-Pressure cell

Segment 31 Sensors

Example of response data:

segment 31 strain, stress, temperature

600

650

700

sg 3

0

2

4

pc 3

d s

760 780 800 820 840 860 88025

30

35

time/days since 29-Apr-0097

T 3

° C

Long Span Cable Bridge

Instrumented Bridge

Dynamic Strain information

link to Vehicle movement

LTA C423 & C823

Flood Gate

Control System

and Components

Monitoring

Base

Station

Flood

Gate

4 x Water Level Sensor

Video Camera

Voltage & Lightning

Surge protection,

Stabilizer from

Power Generator inlet

Monitoring Overview