Model tests on dynamic stress in colliery wastes improved by dynamic compaction

Through physical model tests on colliery wastes improved by dynamic compaction, the dynamic strain gauge DH5939 is used to record the induced dynamic stress. The distribution and rules of the dynamic stress at different depths under different impact loadings and numbers of dynamic compaction are studied. It is shown that the dynamic stress has a single peak, and it has a significant decay to reach the peak under the impact loadings along the depth of the hammer. The decay speed of the horizontal dynamic stress is faster than that of the vertical one, and the range of influence of the vertical dynamic stress is more extensive than that of the horizontal one. The peak value of the dynamic stress attenuates quickly with the depth and similar in an approximate way of negative exponential decay law under the same tamping energy. In addition, for different measuring points , with the increase of compaction number, the dynamic stress tends to be stable after three to six blows. It may provide an efficient way to analyze the mechanism of dynamic compaction.