No abstract

The compaction of soils by light tampers is a traditional and well-developed area of construction. In particular, the standards for hydrotechnical construction specify the use of tamping when constructing dams in layers with a height up to 2 m from unsaturated soils.The possibilities of technologies based on the use of impacts are expanding compared with traditional tamping as the intensity of impacts increases (in combination with a definite technological scheme of compaction) [i, 2, 3]. For purposes of hydrotechnical construction associated with large volumes of works on soil compaction a technology which is highly productive and universal for a number of soils is used, namely, intensive impact compaction [3, 4, 5], which differs from tamping not only by the higher energy of a single impact but also by a special combination of technological parameters: mass, drop height, size and shape of the tam-per~ number of impacts on the same point of the soil surface, distance between adjacent points of compaction on the surface, number of repeated compactions, and pauses between them. The productivity of the technology is from 6000 to i0,000 m 3 of soil per shift and the depth of compaction as up to I0 m and more. The technology is intended not only for compacting of made ground and hydraulic fill in high layers but also for deep compaction of foundations. Finally, under certain conditions it permits compacting saturated cohesive soils contained in the stratum being compacted --in the fill or natural foundation --which is the mainnew qualityachieved with its use. In particular, the range of the allowable moisture contentof soilsbeing placed in an embankment is being expanded, which has a positive effect on the balance and distance of moving soils; in a number of cases the use of the technology permits a marked decrease of expenditures and time on preparing the foundations of structures. These possibilities of the technology of intense impact compaction were checked at the construction sites of the Zagorsk and Kaisiadorys pumped-storage stations. In this case it was found that the use of the technology allows organizing work on the construction of the embankment according to a flow scheme, in which the formation of a high layer for compaction, compaction proper, and checking of its quality can be done practically independently of one another. This most important technological advantage of compacting soils in high layers increases the effectiveness of using allmechanisms engaged in the excavation, delivery, and placement of soil in the embankment and lessens the dependence of the rate of constructing an embankment from cohesive soils onthe climatic conditions [4].