<P> The available techniques can be classified as: </P> <Ol> <Li> Static - a large stress is slowly applied to the soil and then released . </Li> <Li> Impact - the stress is applied by dropping a large mass onto the surface of the soil . </Li> <Li> Vibrating - a stress is applied repeatedly and rapidly via a mechanically driven plate or hammer . Often combined with rolling compaction (see below). </Li> <Li> Gyrating - a static stress is applied and maintained in one direction while the soil is a subjected to a gyratory motion about the axis of static loading . Limited to laboratory applications . </Li> <Li> Rolling - a heavy cylinder is rolled over the surface of the soil . Commonly used on sports pitches . Roller - compactors are often fitted with vibratory devices to enhance their effectiveness . </Li> <Li> Kneading - shear is applied by alternating movement in adjacent positions . An example, combined with rolling compaction, is the' sheepsfoot' roller used in waste compaction at landfills . </Li> </Ol> <Li> Static - a large stress is slowly applied to the soil and then released . </Li> <Li> Impact - the stress is applied by dropping a large mass onto the surface of the soil . </Li>

Describe two methods of ground improvement for cohesionless soil and two methods for cohesive soil