Geophysical and geotechnical assessment of a railway embankment failure
- Authors: Donohue, Shane , Gavin, Kenneth , Tolooiyan, Ali
- Date: 2011
- Type: Text , Journal article
- Relation: Near Surface Geophysics Vol. 9, no. 1 (2011), p. 33-44
- Full Text: false
- Reviewed:
- Description: A geophysical investigation was carried out after the failure of an important railway embankment in the south-east of Ireland, The embankment, which had a long-term history of stability problems, was studied using a combination of ground-penetrating radar (GPR), electrical resistivity tomography (ERT), multichannel analysis of surface waves (MASW) and geotechnical testing. A significant thickening of the ballast layer around the failure location was observed using GPR, which confirmed the existence of an ongoing stability problem in the area. ERT profiles determined the presence and spatial extent of a significant layer of soft clay both beneath and to the east of the embankment, which could have a major impact on its long-term stability. ERT also detected steeply sloping bedrock close to the failure zone that is likely to have contributed to the long-term settlement of the embankment, which necessitated frequent re-ballasting. MASW confirmed the presence of the steeply sloping bedrock in addition to determining the low stiffness (Gmax) values of the embankment fill. High quality sampling of the soft clay deposit was undertaken and strength and compressibility tests revealed the importance of this layer to both the on-going serviceability problems evident for the original embankment and the stability problems encountered by the remodelled section. © 2010 European Association of Geoscientists & Engineers.
Geophysical and geotechnical assessment of a railway embankment failure
- Authors: Donohue, Shane , Gavin, Kenneth , Tolooiyan, Ali
- Date: 2011
- Type: Text , Journal article
- Relation: Near Surface Geophysics Vol. 9, no. 1 (2011), p. 33-44
- Full Text: false
- Reviewed:
- Description: A geophysical investigation was carried out after the failure of an important railway embankment in the south-east of Ireland, The embankment, which had a long-term history of stability problems, was studied using a combination of ground-penetrating radar (GPR), electrical resistivity tomography (ERT), multichannel analysis of surface waves (MASW) and geotechnical testing. A significant thickening of the ballast layer around the failure location was observed using GPR, which confirmed the existence of an ongoing stability problem in the area. ERT profiles determined the presence and spatial extent of a significant layer of soft clay both beneath and to the east of the embankment, which could have a major impact on its long-term stability. ERT also detected steeply sloping bedrock close to the failure zone that is likely to have contributed to the long-term settlement of the embankment, which necessitated frequent re-ballasting. MASW confirmed the presence of the steeply sloping bedrock in addition to determining the low stiffness (Gmax) values of the embankment fill. High quality sampling of the soft clay deposit was undertaken and strength and compressibility tests revealed the importance of this layer to both the on-going serviceability problems evident for the original embankment and the stability problems encountered by the remodelled section. © 2010 European Association of Geoscientists & Engineers.
Railway earthwork stability assessment using geophysics
- Authors: Donohue, Shane , Gavin, Kenneth , Tolooiyan, Ali
- Date: 2012
- Type: Text , Conference paper
- Relation: Fourth International Conference on Site Characterization p. 1519-1525
- Full Text: false
- Reviewed:
- Description: A large portion of the Irish railway network contains earthworks that were poorly constructed mainly because they were built over 100 years ago when scientific understanding of soil behaviour was not nearly as advanced as it is today. Also, engineers involved in the construction of these structures had to work with often unsuitable local materials as sound bulk fill was not able to be transported significant distances. In order to improve the information obtained from site investigation of these poorly constructed earthworks a number of authors have recently suggested complimenting direct geotechnical investigations with a non-invasive geophysical assessment. In addition to providing a review of the factors which cause failure of earthworks, this paper also discusses the capabilities of three geophysical techniques, Ground Penetrating Radar (GPR), Electrical Resistivity Tomography (ERT) and Multichannel Analysis of Surface Waves (MASW) for assessing the stability of railway earthworks. Examples of the use of each technique are provided from forensic investigations into railway earthwork slope failures in Ireland.