Construction of a Reinforced Soil Wall for a working platform for a 1,000 ton Crane and a TBM machine

Location: Wales, United Kingdom
Partner: Geosynthetics Limited, UK
System Offered: Reinforced soil wall using StrataGrid 

 Project Overview

This is a rehabilitation project where sections of a 100 year old structure, Elan Valley Aqueduct (EVA) needed to be replaced. The EVA is an extremely crucial resource as it supplies water to Birmingham and its adjacent areas. The aqueduct is approximately 120 km long, discharges 300 million liters of water every day into the reservoir at Frankley Water Treatment Works (WTW) in Birmingham, and currently supplies water to about 1.2 million people. There was a need to refurbish and modernize the aqueduct so that it can be preserved for the future. For this, a new conduit with a tunnel of 1.8 km length and 3.0 m diameter was proposed to be constructed. For the construction of the bypass conduit, a horizontal working platform of 160 m length and maximum 14.0 m height was required to support the construction traffic, the 1000 ton crane used to assemble the Tunnel Boring Machine (TBM) and the 150 ton TBM.

The solution consisted of a Reinforced Soil Wall using StrataGrid of 120 and 60 kN/m and “site-won” cohesive material as part of the cut-and-fill balance of the project.

To complicate the challenge the entire reinforced soil was required to be made with the site-won material which has a very high content of fine soils, and was very susceptible to weather conditions.

The Innovative Solution

This project was launched by Severn Trent Water as an alternative source of portable water to Birmingham city (population 1.2 million) in future cases of emergency.

To have smooth construction traffic and support the 1000 ton crane, which would be used to assemble the Tunnel Boring Machine (TBM) for the construction of the tunnel, it was necessary to construct a levelled and horizontal working area at one end of the new bypass tunnel, downstream of the project.

For this it was proposed to construct a Reinforced Soil Wall with StrataGrid and on-site won material to surround the location of the cofferdam for the TBM launch shaft. The length of the RSW was 160 m, with a maximum height of 14 m, a slope angle of 85 degrees. A reinforced working platform was constructed, on top of the Reinforced Soil Wall, with selected granular material of 970 mm thickness and biaxial geogrid to distribute the load. For the face a steel mesh B1131 was used to achieve the slope angle of 85deg and each layer was protected with Landlok erosion control mat.

The total height of the Reinforced Soil Wall comprised 43 layers of primary reinforcement with uniaxial StrataGrid™ 120kN/m and 60 kN/m allowing the use of on-site won material as part of the cut-and-fill balance exercise, a key aspect of the project.

 Value Addition to Customers 

  • Saved considerable amount of cost as compared to the conventional method of constructing a concrete wall
  • Environment friendly solution, low carbon emission
  • Technically sound and robust system
  • Rapid construction

About Strata

Strata Geosystems is a leader in the geosynthetics market across the globe. Strata provides end-to-end solutions for soil reinforcement challenges including the supply, design, and construction with our world renowned StrataGrid™ (geogrid) and StrataWeb® (geocells). In addition to the ISO and CE mark, the testing for our products are conducted in GAI-LAP accredited labs across the U.S., U.K., and India. We are also a proud member of the International Geotechnical Society (IGS) promoting advancements in geosynthetics.

Please learn more about us by viewing our website –

About Geosynthetics Limited

Geosynthetics Limited is a successful, dynamic and creative business. Since its incorporation in 1998 the company has grown rapidly into one of the largest independent geosynthetics supplier in the UK. Not just a product supplier, Geosynthetics Limited provides “inspired solutions for civil engineering” through its team of design and application engineers.  They are committed to offering the most comprehensive range of geosynthetic material in the UK.

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