Location

New York, New York

Session Start Date

4-13-2004

Session End Date

4-17-2004

Keywords and Phrases

Sheet Piles, Peat, Surcharge, Finite Element Analysis, Observational Method, Instrumentation

Abstract

The proposed A650 Bingley Relief Road in West Yorkshire, UK, required the construction of a new dual carriageway to relieve traffic congestion in the town of Bingley. Part of the scheme involved constructing the road adjacent to an existing tied sheet pile wall, the “Canal Tied Wall” that had a history of movement. In this area the road passes over a kettlehole with peat and soft silts between 10 m and 14 m deep. The Canal Tied Wall forms the boundary between the realigned canal and the proposed new trunk road. It consists of two sets of steel sheet piles approximately 3.5 m apart with stainless steel tie-bars and mass concrete shear walls connecting them at the top. In May 1994 following the completion of the Canal Tied Wall construction and during excavation of material on the roadside of the wall, a 45 m length of wall moved horizontally in excess of 200 mm (into excavation) with associated maximum vertical movement at the top of the wall of 230 mm. The wall was monitored from 1994 until 2001 and subsequently through the construction of the new road. The Highways Agency's requirement for the Canal Tied Wall was "to carry out stabilisation works ....... together with any remedial works required to the structure to overcome current and future settlement problems". It was originally envisaged by the Highways Agency that a piled solution would be required. The basis of the Tender design was to reduce the load on the wall and hence stabilise the rate of movement towards the canal. The proposed design consisted of excavating the existing fill (originally placed at the time of construction of the wall) to a level about 0.8 m above its base, and constructing a reinforced earth wall with a gap between it and the sheet pile wall. The geotechnical solution that was eventually adopted was to reduce the load exerted on the wall by the ground behind it, and to surcharge the soft deposits to reduce long term settlements. The system adopted used a mass wall constructed of precast lightweight concrete blocks built behind the tied wall. This solution realised savings to the anticipated cost of the scheme whilst meeting the performance requirements of the specification. Numerical analysis was used to assess the anticipated performance of the ground, the existing structure, and the behaviour of the adjacent railway line during the construction operation and into the future. The lateral movements realised in practice were significantly smaller than those predicted using even relatively sophisticated modelling even though the modelling had been calibrated using data gathered during the advance works. This was as a result of changes to the construction sequence made on site. Whilst these were relatively minor the effect on the movements appears to have been significant. Interpretation of consolidation tests proved to be difficult even with the benefit of quite extensive settlement monitoring during and after the advance works. Several possible combinations of parameters gave an equally good fit to the data. The Observational Method was therefore adopted to provide a framework for adjusting the design during construction, subject to the observed behaviour of the ground. The flexibility this provided enabled necessary changes to the surcharge design to be made during construction, while maintaining control over the stability of the wall.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Fifth Conference

Publisher

University of Missouri--Rolla

Publication Date

4-13-2004

Document Version

Final Version

Rights

© 2004 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 13th, 12:00 AM Apr 17th, 12:00 AM

The Construction of the A650 Bingley Relief Road Adjacent to an Unstable Tied Sheet Pile Retaining Structure

New York, New York

The proposed A650 Bingley Relief Road in West Yorkshire, UK, required the construction of a new dual carriageway to relieve traffic congestion in the town of Bingley. Part of the scheme involved constructing the road adjacent to an existing tied sheet pile wall, the “Canal Tied Wall” that had a history of movement. In this area the road passes over a kettlehole with peat and soft silts between 10 m and 14 m deep. The Canal Tied Wall forms the boundary between the realigned canal and the proposed new trunk road. It consists of two sets of steel sheet piles approximately 3.5 m apart with stainless steel tie-bars and mass concrete shear walls connecting them at the top. In May 1994 following the completion of the Canal Tied Wall construction and during excavation of material on the roadside of the wall, a 45 m length of wall moved horizontally in excess of 200 mm (into excavation) with associated maximum vertical movement at the top of the wall of 230 mm. The wall was monitored from 1994 until 2001 and subsequently through the construction of the new road. The Highways Agency's requirement for the Canal Tied Wall was "to carry out stabilisation works ....... together with any remedial works required to the structure to overcome current and future settlement problems". It was originally envisaged by the Highways Agency that a piled solution would be required. The basis of the Tender design was to reduce the load on the wall and hence stabilise the rate of movement towards the canal. The proposed design consisted of excavating the existing fill (originally placed at the time of construction of the wall) to a level about 0.8 m above its base, and constructing a reinforced earth wall with a gap between it and the sheet pile wall. The geotechnical solution that was eventually adopted was to reduce the load exerted on the wall by the ground behind it, and to surcharge the soft deposits to reduce long term settlements. The system adopted used a mass wall constructed of precast lightweight concrete blocks built behind the tied wall. This solution realised savings to the anticipated cost of the scheme whilst meeting the performance requirements of the specification. Numerical analysis was used to assess the anticipated performance of the ground, the existing structure, and the behaviour of the adjacent railway line during the construction operation and into the future. The lateral movements realised in practice were significantly smaller than those predicted using even relatively sophisticated modelling even though the modelling had been calibrated using data gathered during the advance works. This was as a result of changes to the construction sequence made on site. Whilst these were relatively minor the effect on the movements appears to have been significant. Interpretation of consolidation tests proved to be difficult even with the benefit of quite extensive settlement monitoring during and after the advance works. Several possible combinations of parameters gave an equally good fit to the data. The Observational Method was therefore adopted to provide a framework for adjusting the design during construction, subject to the observed behaviour of the ground. The flexibility this provided enabled necessary changes to the surcharge design to be made during construction, while maintaining control over the stability of the wall.