Consultancy

Brian Hawkins has maintained a small practice in order that he can continue to be personally involved with all aspects of his geotechnical work. Although small site investigations works are undertaken and larger ones supervised, most of his time is spent in providing engineering/geotechnical advice and assistance to consultants, contractors, civil/criminal lawyers, insurance assessors, government/local authorities and public bodies on a variety of projects both in the UK and abroad.

With more than 30 years experience in geotechnics, he advises on the implications of the ground conditions at all stages of civil engineering works, from inception to agreement of the final account; where necessary including contractual discussions and legal proceedings.

Examples to illustrate the range of experience include:

Underground - Advice on ground conditions, excavation methods for underground spaces, tunnelling and stabilisation.

Advises Wessex Water and South West Water on numerous tunnel/sewage treatment projects from concept to completion, eg at Plymouth, Weymouth, Bristol, Weston, Swanage and Bath. The works were undertaken in a variety of geological conditions from the extremely strong siliceous sandstone, Carboniferous Limestone and the Devonian slates (drill and blast) to the Cretaceous/Jurassic interbedded limestones and clays (boomheader or full face TBM).

Advised Bath and North East Somerset Council on the danger posed by the shallow disused Combe Down mines and the preparation of proposals for financing and undertaking their stabilisation- appointed Mine Manager for Health & Safety under the Mines Act.

Advised a French/German consortium on 21 underground stations and the initial tunnel connections for the Athens metro. Initially involved in a renegotiation of the contract price. Subsequently asked by the Consortium to work with Bechtel (acting for the Greek Government) to establish and agree the design parameters. Ground conditions varied from very strong limestones to very weak sheared phyllites and schists as well as Quaternary slope deposits. Many of the stations were cut and cover (up to 18 m deep) while six were developed from shafts using NATM.

Designed and supervised the ground investigations and advised on the construction of the first tunnel to be driven in Western Samoa, as part of a hydro-electric scheme.

Highways and associated works - Advice at concept, site investigation, tender, construction and post-construction phases.

Projects undertaken for contractors include the A55 (Rhuallt), M74 (Carlisle-Glasgow) and A487 (Port Dinorwic) in strong/very strong rock involving excavation and rock slope stability. Construction of the M5 and A361 in Somerset involving soft spots partly related to soil piping in the Keuper Marl (Mercia Mudstone) and the cuttings in sandstone/conglomeratic bands.

Worked with the Engineer on the A35 (Charmouth) and A30/A303 (Dorset and Devon) which involved cuttings through and embankments on engineering soils, the M5 cutting through the Clevedon Hills, the A477 Kilgetty Bypass (26/32 m deep cuttingin Coal Measures) and the A5 at Glyn Bends (24 m deep cutting in Ordovician slates). The A39 Bideford and Barnstaple Bypasses were in Carboniferous slates and the Avon Ring Road involved both strong and weak rocks and construction over areas of old coal workings.

Experienced in the implications of weathering and hydrothermal alteration of minerals in igneous rocks for their use in road construction and in concrete aggregate.

Geotechnical member of a risk assessment panel reviewing road construction works for the Highway Agency and insurance firms.

Slope Stability - Undertake slope stability assessments and the design of cut slopes.

Advised local authority on the remedial works in the Clifton Gorge - dislodgement of blocks, meshing/fencing and anchoring; currently assessing the stability of the eastern buttress of the Clifton Suspension Bridge.

Designed rock stabilisation measures for the 12-16 m high cut with outward dipping sandstone and mudrock bands, allowing construction of 28 flats overlooking the waterfront along Hotwells Road, Bristol.

Designed the slope stabilisation measures in interbedded limestones and mudstones for the Swanage Sewage Treatment Works for Wessex Water. In an environmentally sensitive area, these works were placed underground.

Has advised on a number of soil and rock slopes involved with highways, housing and retail developments. Is retained by management companies to carry out periodic checks on developments adjacent to rock slopes.

General - Ground investigations and construction in problematic situations

The Don Valley Stadium over shallow disused coal workings in Sheffield, constructed initially for the World Student Games. For athletes, tolerances for the tracks were crucial. Prepared and supervised grouting programme.

Consultant for the site investigation for Dafen Hospital, Llanelli, preparing the grouting programme and ensuring the stability of the underlying old coal workings.

Advised on large retail/commercial and housing developments over disused mines including coal workings (Bristol), freestone mines (Bath, Bradford on Avon), Fuller’s Earth works (Bath).

Establishing the nature of the ground profile and potential underground dissolution in limestone terrain, particularly in the Bristol/Mendip area.

Ground investigation and design of storm water discharge for a large housing development near Oxford.

Currently preparing proposals for a housing development on flood plain land on the Isle of Wight.

Recognised that the heave problem which occurred at Llandough Hospital, Cardiff, was related to selenite growth due to sulphate generation in dark mudrocks. Recommended remedial measures including the replacement of the integral ground bearing floor slab with pile supported suspended floors.

Investigated cause of distress in houses on the Lias Clay where sulphate generation in dark mudrocks resulted in ground heave due to selenite growth.

Investigated cause of distress in houses on shrinkable/swellable clays and linked this to monitoring sites on the Oxford and Lias Clays already set up to establish the long term influence of oak trees and mature hedges.

Acts as specialist consultant when unexpected ground conditions/problems occur when works are in progress.

Assesses ground conditions and provides information for potential vendors of development sites.

 

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