Dantal, Vishal S. (2009-12). Wireless Monitoring of Railway Embankments. Master's Thesis. Thesis uri icon

abstract

  • Landslides are one of the most dangerous geological hazards. In the United States, landslides cause a damage of $ 3.5 billion and kill 25 to 50 people annually. Shallow landslides occurring near any transportation facilities (railways and highways) can cause economic loss and disturbance of services which lead to indirect economic loss. It also increases the maintenance cost of those facilities. Hence, facilities located near a shallow landslide prone area should be monitored so as to avoid any catastrophic damages. Soil moisture and movement of the soil mass are prime indicators of potential shallow slide movements. This assessment of wireless instruments considers a variety of devices ranging from devices for monitoring tilt and moisture at specific points in the soil mass to ground penetrating radar (GPR), which can give indications of moisture accumulation in soils over a wide spatial extent. For this assessment study, a low cost MEMS accelerometer was selected for measuring tilts and motions. And EC type soil moisture sensor was selected to measure soil moisture content of embankments. The instrumentation of railway embankments works effectively and cheaply when a suspected problem area has already been identified and monitoring is needed over a limited spatial extent. This makes the monitoring system highly localized which often fails to cover potentially new failure prone areas. It is not feasible to use this approach to monitor soil conditions along the entire alignment of the railway. Therefore, another approach, GPR, is defined and explained in this study. GPR measures the dielectric constant value for any given material including soils. In soils, the dielectric constant value depends on the volumetric amount of water content present in a soil. Due to moisture infiltration, there is a reduction in suction value on embankment which indicates a decrease in shear strength of slope. Therefore, a correlation between suction and dielectric constant value is formulated in this study using Complex Refractive index model/Time propagation (CRIM/TP) model for soils. To validate this theoretical correlation, a laboratory study was conducted on pure kaolinite and on normal soil. For pure kaolinite this correlation proves beneficial while, for other type of soil, the correlation was off due to the limitations in filter paper test to measure suction below 2.5pF.
  • Landslides are one of the most dangerous geological hazards. In the United
    States, landslides cause a damage of $ 3.5 billion and kill 25 to 50 people annually.
    Shallow landslides occurring near any transportation facilities (railways and highways)
    can cause economic loss and disturbance of services which lead to indirect economic
    loss. It also increases the maintenance cost of those facilities. Hence, facilities located
    near a shallow landslide prone area should be monitored so as to avoid any catastrophic
    damages. Soil moisture and movement of the soil mass are prime indicators of potential
    shallow slide movements.
    This assessment of wireless instruments considers a variety of devices ranging
    from devices for monitoring tilt and moisture at specific points in the soil mass to ground
    penetrating radar (GPR), which can give indications of moisture accumulation in soils
    over a wide spatial extent. For this assessment study, a low cost MEMS accelerometer
    was selected for measuring tilts and motions. And EC type soil moisture sensor was
    selected to measure soil moisture content of embankments. The instrumentation of railway embankments works effectively and cheaply when a suspected problem area has
    already been identified and monitoring is needed over a limited spatial extent. This
    makes the monitoring system highly localized which often fails to cover potentially new
    failure prone areas. It is not feasible to use this approach to monitor soil conditions along
    the entire alignment of the railway. Therefore, another approach, GPR, is defined and
    explained in this study. GPR measures the dielectric constant value for any given
    material including soils. In soils, the dielectric constant value depends on the volumetric
    amount of water content present in a soil. Due to moisture infiltration, there is a
    reduction in suction value on embankment which indicates a decrease in shear strength
    of slope. Therefore, a correlation between suction and dielectric constant value is
    formulated in this study using Complex Refractive index model/Time propagation
    (CRIM/TP) model for soils. To validate this theoretical correlation, a laboratory study
    was conducted on pure kaolinite and on normal soil. For pure kaolinite this correlation
    proves beneficial while, for other type of soil, the correlation was off due to the
    limitations in filter paper test to measure suction below 2.5pF.

publication date

  • December 2009