E

very year all over the world many lives and properties are lost due to many geological catastrophes like,

landslide or landslip. Manual and electronic monitoring systems are used for predicting

the landslide. The

m

anual monitoring syst

em is laborious and not

practical. And most of the electronic systems are complex and

expensive.

A

wireless sensor network

in conjunction with

a

n underground pretension cable with a strain gage

sensor attached at one end

is

proposed for a simple landslide

monitoring system

. A mathematical model has been

developed for the system and the model is verified by simulation. The result shows that an early prediction of the

landslide is possible

by using the

developed

system



Anwar, Farhat

Ibrahimy, Muhammad Ibn

Motakabber, S. M. A.

English

The International Islamic University Malaysia Repository

Third International Conference on Geotechnique, Construction Materials and Environment, Nagoya, Japan, Nov. 13-15, 2013, ISBN: 978-4-9905958-2-1 C3051 WIRELESS SENSOR NETWORK FOR LANDSLIDE MONITORING S. M. A. Motakabber, M. I. Ibrahimy and F. Anwar Faculty of Engineering, International Islamic University Malaysia, Kuala Lumpur, Malaysia ABSTRACT Every year all over the world many lives and properties are lost due to many geological catastrophes like, landslide or landslip. Manual and electronic monitoring systems are used for predicting the landslide. The manual monitoring system is laborious and not practical. And most of the electronic systems are complex and expensive. A wireless sensor network in conjunction with an underground pretension cable with a strain gage sensor attached at one end is proposed for a simple landslide monitoring system. A mathematical model has been developed for the system and the model is verified by simulation. The result shows that an early prediction of the landslide is possible by using the developed system. Keywords: Wireless Sensor Network, Landslide, Automated Monitoring System, Strain Gage Sensor, Geological Catastrophe INTRODUCTION Worldwide, landslides cause about 1,000 deaths per year and property damage of approximately US$ 4 billion [1]. Existing manual solution is insufficient and sometimes it is costly for landslide prediction and detection. Installing a single sensor for monitoring a wide hilly target area is not sufficient. Most of the cases, the property of the hill is changed in about every 10-15 meters distance. Wiring with multiple sensors to a central data logger is also not reliable and practical as well since it requires frequent maintenance. Therefore, wireless sensor network system is used for real-time landslide monitoring. Thin film strain gage pressure sensor with high accuracy pressure measurement is clamed in the system [2]. A simple pretension underground cable attached with a strain gage at one end can be easily used to measure the pressure of the soil as shown in Fig. 1.  Fig. 1 Basic arrangements of the proposed wireless sensor network system for landslide monitoring. The measured pressure can be used to calculate the landslide prediction and detection. A number of same kinds of sensor setup can be used for monitoring a wide land area. In this case, each sensor is defined by a unique number within a wireless network. This ID number can be easily used to locate the landslip zone. A majority of the wireless sensor network arrangements [3], [4] are mainly data collection networks. The wireless sensor network recurrently collects the respective data and collaboratively processes the measurements from the field under study before forwarding them to the central monitoring station. The central monitoring station executes more computationally-intensive algorithms such as finite element modeling and parameter identification [5], [6] and acts as the expert interface to the system. A wireless communication system can be used to transmit the sensors sampled data and relevant information to a distant central database server computer for analysis purpose. The instant conveyed information would allow us to implement instant disaster rescue measures and to notify the land user to protect the people’s lives and properties. SENSOR MODELING A simplified force diagram of the proposed landslide pressure sensor that is, pretension cable with strain gage is shown in Fig. 2.  Assume that a pre tensioned still cable length of L is attached at two end supports under the soil. If the linear expansion coefficient of the cable is αL and the surrounding temperature of the cable is changed ∆T degree Kelvin then the change of cable length ∆LT can be calculated as follows: Fig. 2 Simplified force diagram of the proposed landslide pressure sensor. 685 GEOMATE-Nagoya, Nov.13-15, 2013  𝛂𝛂𝐋𝐋 = 𝟏𝟏𝐋𝐋 ∆𝐋𝐋𝐓𝐓∆𝐓𝐓  (𝟏𝟏) 𝐎𝐎𝐎𝐎,   ∆𝐋𝐋𝐓𝐓 = 𝛂𝛂𝐋𝐋𝐋𝐋∆𝐓𝐓  (𝟐𝟐) When the land is slightly moved S distance from its initial position then it creates a force F on force plate as well as on the cable. If the Yang’s modulus of the cable is E then at force equilibrium condition,    𝐄𝐄 = 𝐅𝐅/𝐀𝐀∆𝐋𝐋/𝐋𝐋  (𝟑𝟑) Where, A is the cross section area of the cable and ∆L is the change in length of the cable due to force.  By considering the temperature effect, Eq. (3) can be rewritten as, ∆𝐋𝐋 = 𝐅𝐅(𝐋𝐋 + ∆𝐋𝐋𝐓𝐓)𝐄𝐄𝐀𝐀 (𝟒𝟒) The work UE done by the soil movement can be calculated by Eq. (5). 𝑼𝑼𝑬𝑬 = 𝑭𝑭𝑭𝑭  (𝟓𝟓) The potential energy UW stored in the cable can be calculated as follows:  𝑼𝑼𝑾𝑾 = � 𝑭𝑭∆𝑳𝑳𝟎𝟎𝒅𝒅∆𝑳𝑳  (𝟔𝟔) From Eq. (4) and Eq. (6), 𝑼𝑼𝑾𝑾 = � 𝑬𝑬𝑬𝑬∆𝑳𝑳(𝑳𝑳 + ∆𝑳𝑳𝑻𝑻)∆𝑳𝑳𝟎𝟎 𝒅𝒅∆𝑳𝑳 𝐎𝐎𝐎𝐎, 𝑼𝑼𝑾𝑾 = 𝑬𝑬𝑬𝑬∆𝑳𝑳𝟐𝟐𝟐𝟐(𝑳𝑳 + ∆𝑳𝑳𝑻𝑻)= ∆𝑳𝑳𝑭𝑭𝟐𝟐 (𝟕𝟕) From Eq. (5) and Eq. (7), the potential energy US stored in strain gage substrate is calculated as follows: 𝑼𝑼𝑭𝑭 = 𝑼𝑼𝑬𝑬 − 𝑼𝑼𝑾𝑾 = 𝑭𝑭𝑭𝑭 − ∆𝑳𝑳𝑭𝑭𝟐𝟐𝐎𝐎𝐎𝐎, 𝑼𝑼𝑭𝑭 = 𝑭𝑭�𝑭𝑭−∆𝑳𝑳𝟐𝟐�   (𝟖𝟖) Again, if the Yang’s modulus of the strain gage substrate is ES then at force equilibrium condition, 𝑭𝑭𝑭𝑭 = 𝑬𝑬𝑭𝑭 𝑬𝑬𝑭𝑭 ∆𝑳𝑳𝑭𝑭𝑳𝑳𝑭𝑭                                                            (𝟗𝟗) Where, AS and LS are the cross section area and length of the substrate respectively. FS is the force on the substrate and ∆LS is the change in length of the substrate due to force.  From Eq. (9), 𝑼𝑼𝑭𝑭 = � 𝑭𝑭𝑭𝑭 ∆𝑳𝑳𝑭𝑭𝟎𝟎𝒅𝒅∆𝑳𝑳𝑭𝑭 𝐎𝐎𝐎𝐎, 𝑼𝑼𝑭𝑭 = 𝑬𝑬𝑭𝑭𝑬𝑬𝑭𝑭∆𝑳𝑳𝑭𝑭𝟐𝟐𝟐𝟐𝑳𝑳𝑭𝑭= 𝑬𝑬𝑭𝑭𝑬𝑬𝑭𝑭∆𝑳𝑳𝑭𝑭𝟐𝟐𝟐𝟐  (𝟏𝟏𝟎𝟎) By combining Eq. (8) and Eq. (10) 𝑭𝑭�𝑭𝑭 −∆𝑳𝑳𝟐𝟐� = 𝑬𝑬𝑭𝑭𝑬𝑬𝑭𝑭∆𝑳𝑳𝑭𝑭𝟐𝟐𝟐𝟐𝑳𝑳𝑭𝑭𝐎𝐎𝐎𝐎,∆𝑳𝑳𝑭𝑭𝑳𝑳𝑭𝑭= � 𝟐𝟐𝑭𝑭𝑳𝑳𝑮𝑮𝑭𝑭𝑬𝑬𝑮𝑮𝑭𝑭𝑬𝑬𝑮𝑮𝑭𝑭�𝑭𝑭 −∆𝑳𝑳𝟐𝟐�   (𝟏𝟏𝟏𝟏) If the gage factor and the temperature coefficient of the strain gage are G and α respectively then the change of resistance ∆R of the strain gage with respect to the initial resistance R is calculated as follows: ∆𝑹𝑹= 𝑹𝑹�𝑮𝑮∆𝑳𝑳𝑭𝑭𝑳𝑳𝑭𝑭+ 𝜶𝜶𝑻𝑻�    (𝟏𝟏𝟐𝟐) By combining Eq. (11) and Eq. (12) ∆𝑹𝑹 = 𝑹𝑹�𝑮𝑮� 𝟐𝟐𝑭𝑭𝑳𝑳𝑭𝑭𝑬𝑬𝑭𝑭𝑬𝑬𝑭𝑭�𝑭𝑭 −∆𝑳𝑳𝟐𝟐�+ 𝜶𝜶𝑻𝑻�   (𝟏𝟏𝟑𝟑) From Eq. (4), if the Yang’s modulus E of the cable is very large then ∆T≈ 0 and Eq. (13) can be rewritten as Eq. (14).  686 GEOMATE-Nagoya, Nov.13-15, 2013 ∆𝑹𝑹 = 𝑹𝑹�𝑮𝑮� 𝟐𝟐𝑭𝑭𝑭𝑭𝑳𝑳𝑭𝑭𝑬𝑬𝑭𝑭𝑬𝑬𝑭𝑭+ 𝜶𝜶𝑻𝑻�   (𝟏𝟏𝟒𝟒) Eq. (14) indicates that the change of strain gage resistance is directly proportional to the squire root of the force and displacement of the land. RESULT AND DISCUSSION A PSPICE simulation is studied for the proposed landslide sensor for monitoring system. The result is shown in Fig. 3. In this simulation, it is considered that the Yang’s modulus E of the cable is infinity and the temperature coefficient of the strain gage is very low. In Fig. 3, it is noticed that a very slow landslide effect is present at the beginning and about four months later, the effect is more visible. The sensor ID number 001 shows that its resistance is changing exponentially; it means a massive landslide would be happened within short time in the region under the sensor.   Fig. 3 Change of strain gage resistance with time. CONCLUSION A pretension cable and a strain gage sensor can be used for landslide prediction and detection purpose. The change of strain gage resistance is a direct indication of the landslide effect and no need to measure the exact value of the force or displacement of the soil. This principle can help to develop a simple and low cost real-time landslide or landslip monitoring system. According to the mathematical model, Eq. (13), for an efficient system, the Yang’s modulus of the cable must be very large. Since, the still and carbon fiber cable have very large Yang’s modulus; they can be used in this development. REFERENCES [1] Lee S and Pradhan B, “Landslide hazard mapping at Selangor, Malaysia using frequency ratio and logistic regression models”, Landslides, Vol. 4, No. 1, 2007, pp. 33-41. [2] Hongye W, Kun L, Zhichou A, Xu W and Xun H, “Ion-beam sputtered thin-film strain-gage pressure transducers”, Sensors and Actuators A: Physical, Vol. 35, Issue 3, 1993, pp. 265-268. [3] Szewczyk R, Polastre J, Mainwaring A and  Culler D, “Lessons from a sensor network expedition”, in proceedings of the 1st European Workshop on Sensor Networks, January 2004. [4] Xu N, Rangwala S, Chintalapudi KK, Ganesan D, Broad A, Govindan R and Estrin D, “A wireless sensor network for structural monitoring”, in proceedings of the 2nd international conference on Embedded Networked Sensor Systems, pp. 13–24, USA, 2004.  [5] Kuppusamy T, Sheng J, Parker JC and Lenhard RJ, “Finite-element analysis of multiphase immiscible flow through soils”, Water Resources Research, Vol. 23, Issue 4, 1987, pp. 625-631. [6] Hoshiya M and Sutoh A, “Kalman Filter-Finite Element Method in Identification”, J. Eng. Mech., Vol. 119, Issue 2, 1993, pp. 197–210.  687 

Wireless sensor network for landslide monitoring

http://irep.iium.edu.my/33236/1/Paper-2.pdf

Wireless sensor network for landslide monitoring

Abstract

Similar works

Full text

Available Versions

The International Islamic University Malaysia Repository