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. MILLS M r Page, M r Curtisand M r Mills Regarding the test on the sheet piling, some additional information may be of interest. The loads in four of the tie rods were monitored: two of these rods were instrumented at both quay and anchorage ends and two at the quay ends only.Figs 21 and 22 show that the loads in the quay ends were quite low initially at only 100-200 kN and it was not until the final placing of the 2 m of Thanet sand compacted in 30 cm layers, that the loads increased to 400-500 kN, about two thirds of the 700 kN design load. From Fig. 22 it appears that initially the anchorage loads were dissipated in friction along the rod without any load being transmitted to the anchorage, the rods being under temporary compression at this end.81. A Stothert & Pitt 6 t vibrating roller (developing 96 t impact load) was used to compact the sand and this clearly helped to generate more realistic earth pressures transmitting loads of up to 40 t to the anchorages. If the design had been of the form in which the sheeting was driven entirely through existing soil with the face dredged after completion it is possible that the anchorage loads would have remained low, suggesting an unnaturally high factor of safety.82. Nine piezometer tubes were also installed to monitor movement of groundwater level. Only one of these continued to function throughout the construction period and this happened to be nearest to the instrumented sheet piles. A typical result is given in Fig. 23. This shows groundwater level following the rising tide very closely, which may not be entirely accurate, and could have been distorted by the presence of the piezometer tube itself. With the falling tide, groundwater level is held just below mid-tide and this is probably a true indication of the situation at this section. The design was based on groundwater being at mid-tide level and to that extent appears to be slightly conservative.M r J. N. Black, PLA, Tilbury Docks There were several reasons for choosing a site on the riverside rather than within the dock. The third-generation container ships were just beginning to be built, and we felt it would be advantageous to have a facility which obviated the need for them to go through the lock : the time-saving was important, as most of the large ships using Tilbury have to use the tide for the depth of water. Another reason was

In 8 35 of the Paper, filling between the hinge face plate and the hinge casting was referred to. This was provided because it was very difficult to fasten the hinge accurately to a concrete wall. The face plate was put in place first: A gap of about t. in. was left between the two and then gritted epoxy resin was poured down between them to fill the gap. We were rather afraid of doing this without some experimental testing, so we had a test rig built in the laboratory. It was about half the size of the actual job, and we tremmied the epoxy resin into this set-up through very thin pipes. We had some Perspex windows in the face shutter to see how it behaved, and to our satisfaction the gap filled up perfectly. 56.The rail bedding referred to in 8 36 was done with a similar mixture and proved extremely effective; we examined the bedding 12 months or so after it had been in service and it appeared to be absolutely sound, with no signs of cracking up or deterioration of any sort.57. The radial arms were fabricated allowing for a nominal gap of 1 in. at each end, and after site welding and adjustment of the walings the gaps at the hinge end were carefully measured and packings were machined to fit, tapered where necessary. It was found impracticable to repeat this procedure at the waling end owing to lack of flatness of the waling flanges, and the gaps were filled with an epoxy resin grout similar to that used between the hinges and face plates. The bolts holding the radial arms to the hinges and walings, together with the bolts in the other major connexions, were tensioned to predetermined loads to prevent opening of the joints under live load conditions. 58.In 8 48 brief mention is made of troubles which have occurred with the bogie wheel bearings. These troubles have been the subject of considerable investigation and re-design and modifications to the bogies are now in hand. The original design is illustrated in Fig. 4 of the Paper. The design loading was compounded from the vertical load and a transverse frictional force at rail level limited by the 12.5% coefficient of friction of the articulation pin bearing bush. It was considered that any transverse tracking forces between wheel and rail could be neglected owing to the conical geometry adopted. The resulting maximum pressure on the Railko bearing material, taking into account the flexure of the shaft and the compressibility of the bearing material, gave a factor of safety of three on the ultimate compressive strength of the Railko.59. It is estimated that the sector gates were operated about 2000 sequences during assembly, commissioning and in service, but in October 1972, rough and erratic running of the east gate was noticed and the gates were withdrawn from service. The bogies were removed and returned to the Contractor's works for dismantling and examination.60. Of the total of eight bearings, in five the Railko material had disinegrated and the shafts worn to a depth of 10 mm in places. The remaining bearings were in fair condition but with some signs...

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