Synopsis The paper, describes, and gives the results of three loading tests carried out on bored piles constructed in the London clay at kensal Green Gas Works. Two of the tests were carried up to the ultimate load of the piles. During the boring for the piles, samples of clay were taken for teats. and in two of the borings, loading tests were carried out on plates placed at the bottom of the boring at three different depths. Further strength tests on clay from the same site are quoted, and a correlation is made between the shear strength and the loading tests. The results of the loading tests on piles do not agree with the value given by the Meyerhof-Murdock formula. Further loading tests on bored piles in London clay at other sites are quoted in which the test load satisfactorily carried (not the ultimate load) is con- siderably higher than the ultimate given by Meyerhof and Murdock. A method of design suggested by the Authors is stated. Cette communication décrit et donne les résultats de trois essais de charge effectués sur des pieux forés, enfoncés dans l'argile de Londree a` usine à gaz de Kensal Green. Deux des essais ont été effectés jusqy'a` la charge limite des pieux. Pendant le forage, dee échantillons d'argile ont été prélevés, et en deux des sondages, des essais de charge out été effectués sur des plaquea se trouvaut au fond du sondage à trois profondeurs différentes. On cite d'autres essais de résistance sur l'argile provenant du même terrain, et on établit une corrélation entre la résistance au cisaillement et les essais de charge. Les résultats des essais de charge sur les pieux ne s'accordent pas avec la valeur donnée par la. formule Meyerhof-Murdock. On cite des essaie supplémentaires sur des pieux forésenfoncés dane l'argile de Londres en d'autres terrains, Où la charge d'essai portée d'une façon satisfaisante (non la charge limite) est beaucoup plus élevée. que la charge limite citée par Meyerhof et Murdock. Une méthode de construction proposée par les auteurs est donnée

315in progress, calling for either steam plant, compressors with their appropriate tools, pumps, etc.outputs On the, beach and gantry sections 164 pipes were laid in 129 working weeks. For most of the time two units of two or three gangs each were employed. The pipe laying varied from two per unit week t o one pipe in 4 weeks when conditions were bad.The number of unit weeks waa 224, giving an average of 0.73 pipes, or 18 f t 3 in. per week for each unit.The total cost of the work cannot be closely assessed until after removal and disposal of surplus materials, but will probably be in the region of ;E375,000. The pipes were supplied under a separate contract. ACRNOWLEDQEMENTSThe Consulting Engineers responsible for the design and supervision of the work were A. H. S. Waters and Partners, and the Authors would like to record their appreciation of the readiness of the Engineers to consider possible amendments t o the design to meet problems of construction, and of the helpful co-operation of the Resident Engineer to the Corporation, MrHeysham) said that on pp. 303-305 various methods of construction were outlided, all of which had been considered. Method (e) had been put forward by other contractors some years earlier, when Mr Kilvington knew less about such methods, but he had felt that it could not possibly succeed unless some evidence was put forward t o the contrary. He thought the method adopted was the only practicable one, bearing in mind the need for economy. He had made trial holes on the shore, but he thought the Authors would agree that, though a valuable general indication, those which were nearest were frequently the most dissimilar, so that it was impossible t o attach the normal importance to them. The mention of sand was specially interesting to them a t Morecambe, apart from the question of scour, because there was a tendency for a shortage of sand on their foreshore Until about 10 years ago on that part of the beach and just to the east of it there had been huge accumulations of sand, but much of it had disappeared. He hoped that it was now beginning t o return; certainly sand was accreting, and he hoped it would continue t o do so.Finally, if the contractors contemplated a similar contract, would they, with the experience which they had now gained, adopt similar methods? Downloaded by [] on [11/09/16].

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M r HaswellI would refer to the railway tunnel constructed, also under the Severn, nearly a century ago in the vicinity of the new tunnel and to the various changes in context between the two, with particular reference to safety, methods of attack and the modern techniques available nowadays.94. In the concept of a tunnel to be driven in treacherous ground it is important to have a proper balance between the contract risk and the contract responsibility: here was a good example where both the cost/reimbursement-with twin targetsand the admeasurement types of contract were used on the same project successfully. Naturally this leads to the suggestion that similar cost/reimbursement contracts might be adopted more widely, particularly in the tunnelling field, with their possible advantages over conventional admeasurement types of contract.95. In the section of the Paper on technical aspects it was pointed out that by a novel type of gauge the radial stress loading was measured and confirmed the existence of considerable residual rock stresses which had first been referred to by the Swiss geologist Heim in 1878. Results of the tests showed a loading much greater than the total overburden and, as might be expected, generally in the horizontal position. The radial stress diagram was obviously not in equilibrium, indicating that tangential as well as radial stress is required to give a true loading picture on tunnel linings. Further research should aim in this direction. M r D. M. Cherry, Director General, Transmission Development and Construction Division, CEGBThe normal business of my division of the CEGB is to provide for the bulk haulage of electricity. This involves a very wide range of civil works. The Severn Tunnel is the third and the longest major tunnel which has been undertaken and within the last few weeks work has begun on a fourth, under the River Medway. It occurred to me that it might be worthwhile explaining briefly why the CEGB embarked on this tunnel and what use it intends to make of it.97. As part of building the new large power stations at Pembroke and Aberthaw, where there was that rare thing, favourable sites and sites acceptable to the public, the CEGB had to provide two twin 400 kV connexions from South Wales to Gloucester and to Melksham. It was planned to take the southerly or Melksham line across the Severn at Sharpness where a comparatively inconspicuous low height crossing could be made. This route was acceptable to the county planning authorities, but less so to amenity societies, particularly as to the effect of the line in thevale of Berkeley. After a public inquiry the CEGB was directed to take a route further west, which required less overhead line but a cable tunnel under the Severn and Wye.The net effect of this on the overall scheme was to add approximately E4 million to the costs and some two years to the completion time.98. In the tunnel two groups each of three cables are being installed: each group must carry the capacity of the overhead line, which is 2600 MVA, or rather more...