Use Of Grout Research Articles

Recent applications of grouting : Merrifield, C M Ground EngngV17, N5, July 1984, P7–10

The author reports on the British Geotechnical Society's January 1984 informal meeting where three speakers provided examples of the use of grouting in conditions varying from the highly saline conditions of the Dead Sea to fabric formwork for over 5000 km of North Sea gas and oil pipelines. Extensive laboratory and site trials were needed to produce a slurry of the required characteristics for the 14 km long diaphragm wall in Jordan. New anchorages were installed in the floor of an existing dry dock at Alexandria in Egypt. The installation of 400 tonne anchorages for anchoring marine piles required extensive pre-grouting. The concept of squeeze grouting, needs careful matching of rheological properties of grout and ground to control hydrofracture. Combination grouting has been used to stabilise milonitic material in advance of a tunnelling face. Squeeze grouting has also been used effectively for precompression. A brief illustration was given of the variety of grout applications in civil engineering, mining and offshore engineering. These included large diameter piles in Jeddah, tunnelling in Hong Kong without the use of compressed air and the grouting of the Asprokremmos Dam. (TRRL)

Use of grouting in the construction of linings for high-pressure hydraulic tunnels (Discussion)

1. Precompression of the rock is a necessary condition for constructing the linings of high-pressure tunnels, by applying grout as the principal material for limiting the loss of water. 2. By means of grout applied under high pressures causing rock deformations, such as additional opening of the existing fissures and development of new fissures, a degree of precompression may be attained adequate for preventing the formation of fissures under the action of the internal pressure. As one of the indirect indexes expressing the adequacy of the precompression obtained, use may be made of the “critical” pressure, which is determined by applying pressure to rocks or to drill holes. 3. The diversity and indeterminateness of the available factors make difficult and inaccurate the analytical determination of required grouting pressure. As a guide for the evaluation of this pressure, the formula proposed by Prof. V. S. Eristov may be utilized, by dropping from it the tensile strength of the rock. This pressure cannot be lower than the expected internal head on the lining. 4. When determining the safety factor by use of the formula proposed by Prof. V. S. Eristov, it is necessary to take into consideration the drop of the grouting pressure with increased distance from the grout holes, as well as the reduction of the grout volume as a result of shrinkage and expulsion of water.

THE THAMES-LEE WATER MAIN.

The Paper describes the design and construction of a concrete-lined tunnel, together with the necessary pumping plant, which will be used to transfer water from the River Thames to the Lee Valley storage reservoirs of the Metropolitan Water Board. This tunnel is believed to be the longest in Europe and the longest tunnel in soft strata in the world. This tunnel main has been made necessary because insufficient water is available from the River Lee to meet the needs of East London. The main was designed as a gravity main. Electrically driven boreholetype pumps located in a shaft at the Lee Valley end of the main deliver the water into the reservoirs. Whilst the shafts were lined with bolted reinforced concrete and cast iron segmental rings of conventional design. the tunnel was lined with unreinforced tapered concrete blocks which were expanded against the ground under the pressure of the rams of the shield used in driving the tunnel, thus avoiding the use of grout or bolts. Other features dealt with in the Paper include a new form of rotary shield which sustained a rate of driving of 360 ft per week for long periods, lining the tunnel with cement mortar by mechanical means, the design and construction of a siphon intake, and a Venturi meter in tunnel.