Location

Arlington, Virginia

Session Start Date

8-11-2008

Session End Date

8-16-2008

Abstract

Slope failures often occur in highways located in the mountainous terrain of Northern Thailand. There are several factors which induce those failures. The construction material consists of cohesionless decomposed granite. The highway embankment is steep over 30 m in height. The rainfall is very high during the monsoon season. Due to limitation of right of way, difficulty in the reconstruction and environmental consideration, geogrid reinforced embankment is introduced. The advantages of using the reinforced structure are to use less material because the very steep slope can be maintained and the vegetative cover is feasible. However, the method is expensive, economical design is necessary, i.e., very steep slope, wide spacing of geogrid and the minimum length of geogrid. The research was commenced on a selected failed slope repaired by using geogrid reinforcement. Borings were performed with soil samples taken to our laboratory to determine the engineering properties of the embankment materials as well as the soil profile of the foundation. The design and construction was verified by installing several geotechnical instruments, i.e., inclinometers, piezometers, observation wells, surface settlement plates and pressure cells. Long term monitoring data were recorded and analyzed. The FEM model was established and calibrated with measuring data. The analysis results indicated that surface runoff and seepage were the major causes of the failure. In order to prevent the future failure, good surface drainage is required to eliminate the surface runoff and the horizontal drainage pipes are needed to reduce the amount of underground water. The FEM analysis shows that using the geogrid reinforcement improves the slope stability; however, the length of geogrid should be long enough in order to fully develop the anchorage end.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Sixth Conference

Publisher

Missouri University of Science and Technology

Publication Date

8-11-2008

Document Version

Final Version

Rights

© 2008 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Aug 11th, 12:00 AM Aug 16th, 12:00 AM

Repair of a Failed Slope Using Geogrid Reinforcement

Arlington, Virginia

Slope failures often occur in highways located in the mountainous terrain of Northern Thailand. There are several factors which induce those failures. The construction material consists of cohesionless decomposed granite. The highway embankment is steep over 30 m in height. The rainfall is very high during the monsoon season. Due to limitation of right of way, difficulty in the reconstruction and environmental consideration, geogrid reinforced embankment is introduced. The advantages of using the reinforced structure are to use less material because the very steep slope can be maintained and the vegetative cover is feasible. However, the method is expensive, economical design is necessary, i.e., very steep slope, wide spacing of geogrid and the minimum length of geogrid. The research was commenced on a selected failed slope repaired by using geogrid reinforcement. Borings were performed with soil samples taken to our laboratory to determine the engineering properties of the embankment materials as well as the soil profile of the foundation. The design and construction was verified by installing several geotechnical instruments, i.e., inclinometers, piezometers, observation wells, surface settlement plates and pressure cells. Long term monitoring data were recorded and analyzed. The FEM model was established and calibrated with measuring data. The analysis results indicated that surface runoff and seepage were the major causes of the failure. In order to prevent the future failure, good surface drainage is required to eliminate the surface runoff and the horizontal drainage pipes are needed to reduce the amount of underground water. The FEM analysis shows that using the geogrid reinforcement improves the slope stability; however, the length of geogrid should be long enough in order to fully develop the anchorage end.