Design of Monitoring and Early Design of Monitoring and Early Warning System for Geohazard in Warning System for Geohazard in

Three Gorges Reservoir Area Three Gorges Reservoir Area Using InfrasoundUsing Infrasound

The 2008 Infrasound Technology Workshop, BermudaThe 2008 Infrasound Technology Workshop, Bermuda

Ning QiuNing Qiu11, Zuo-Xun Zeng, Zuo-Xun Zeng11, Yi-Chun Yang, Yi-Chun Yang22

11China University of Geosciences, Wuhan 430074, ChinaChina University of Geosciences, Wuhan 430074, China22Institute of Acoustics, Chinese Academy of Sciences, Beijing 100080, ChinaInstitute of Acoustics, Chinese Academy of Sciences, Beijing 100080, China

Email: QiuNing@cug.edu.cnEmail: QiuNing@cug.edu.cn

OUTLINEOUTLINE

• Research background & significance

• Methodology

• Thinking for design

• Problems that need to be resolved

Yangtze RiverYangtze River Three Gorges Three Gorges

The Three Gorges Dam is a hydroelectric river dam that spans the Yangtze River in Sandouping town, Yichang city, Hubei province, China.

Yichang Yangtze RiverYangtze River

Gezhouba Dam

May 14, 2007 Landslide site located in Qingtaiping, Badong County, May 14, 2007 Landslide site located in Qingtaiping, Badong County,

Hubei ProvinceHubei Province

Research BackgroundResearch Background

• With the progress of the Three Gorges Dam Project, geohazard have become increasingly prominent.

• The reservoir area prone to landslides, collapses, cracks, and earthquake disaster because the complex terrain and geological conditions.

Research SignificanceResearch Significance

• It is of significance to monitor and foresee geohazard in the reservoir area.

• Here we introduce our design of monitoring and early warning system for geohazard in Three Gorges reservoir area using Infrasound.

Methodology Methodology

• Infrasound may be abnormal during geological Infrasound may be abnormal during geological disasters.disasters.

• Such as debris and earthquake occurred. The Such as debris and earthquake occurred. The formation and movement of debris flow in its formation and movement of debris flow in its basin will generate infrasound, and spread to the basin will generate infrasound, and spread to the surrounding air medium. surrounding air medium.

• Velocity of infrasound is much larger than that of Velocity of infrasound is much larger than that of debris flow, so we can monitor and forecast debris flow, so we can monitor and forecast debris flow using infrasound.debris flow using infrasound.

MethodologyMethodology

• The sudden vertical displacement brought about by earthquake will generate acoustic-gravity wave which can be observed in distance to monitor earthquake, especially to monitor earthquake precursor.

• So we try to monitor the geohazard for the Three Gorges reservoir area in China by design a infrasound array system.

Thinking for DesignThinking for Design

• The infrasound monitor system is comprised of The infrasound monitor system is comprised of two observation stations arranged in two observation stations arranged in Badong Badong CountyCounty inside the reservoir area and in inside the reservoir area and in Wuhan Wuhan CityCity respectively. respectively.

Wuhan infrasound observatory station located inWuhan infrasound observatory station located in the campus of the campus of China University of GeosciencesChina University of Geosciences

Thinking for DesignThinking for Design• Each station has respectively arranged a kind of augmentable linear Each station has respectively arranged a kind of augmentable linear

array in the form of quasi-uniform linear array and additional array in the form of quasi-uniform linear array and additional amending direction sensors.amending direction sensors.

C1 R1R1

C2C2

R2R2L2L2 L1L1

Amending Direction Sensor Amending Direction Sensor

R3R3L3L3

dd3d3d

ddQuasi-Uniform Linear Array Quasi-Uniform Linear Array

5d5d

The linear array comprises eight sensors arranged in several different The linear array comprises eight sensors arranged in several different uniform intervals along a line. Amending direction sensor is situated at uniform intervals along a line. Amending direction sensor is situated at certain point in mid-perpendicular of linear array in order to reduce certain point in mid-perpendicular of linear array in order to reduce multiplicity in determine the direction of arrival.multiplicity in determine the direction of arrival.

Ele NumEle Num ApertureAperture Array StructureArray Structure

77 1818 - 5 - 3 - 1 - 1 - 3 - 5 -- 5 - 3 - 1 - 1 - 3 - 5 -

Thinking for DesignThinking for Design

• The sensors used in the system are CDC-2B capacitances The sensors used in the system are CDC-2B capacitances infrasonic receiver which can observe frequency ranging infrasonic receiver which can observe frequency ranging 0~20Hz. The, measurement resolution is 750mV/LPa. 0~20Hz. The, measurement resolution is 750mV/LPa.

CDC Capacitive CDC Capacitive InfrasonicSensorInfrasonicSensor

Wind Resistance Equipment Wind Resistance Equipment

Wind CapWind Cap

PVC pipePVC pipe

Thinking for DesignThinking for Design• Infrasonic wave signal collected by sensor is transferred Infrasonic wave signal collected by sensor is transferred

from observation stations to Data Processing Center in from observation stations to Data Processing Center in CUG, using telecommunication networks, and then we CUG, using telecommunication networks, and then we can process and analyze the infrasonic signals. can process and analyze the infrasonic signals.

24 Bit 24 Bit A/D CardA/D Card

Infrasound Sensor ArrayInfrasound Sensor Array

PC PC Internet Internet AccessAccess

Problems that need to be resolvedProblems that need to be resolved

• Observations all-weather infrasound near the reservoir area can be achieved on monitoring geohazard in Yangtze River Three Gorges. There are still problems to be considered in the system:

• ( ) in the conditions of using few sensors, this need more Ⅰrational array layout mode;

• ( ) sensors in field can lasting stability in some way; Ⅱ

• ( )the amount of data acquisition, real-time transmission, Ⅲstorage and backup need higher demands in hardware and software.

Comments and SuggestionsComments and Suggestions are most in need for us!!are most in need for us!!

Thanks for your attention!Thanks for your attention!

Email: QiuNing@cug.edu.cn Add. #388 Lumo Rd, Wuhan 430074, China Email: QiuNing@cug.edu.cn Add. #388 Lumo Rd, Wuhan 430074, China