The Rayleigh wave velocity of dynamic compaction foundation which comprises detritus soil is tested under three groups of different soil-rock ratios to research soil-rock ratio and large size rock block influence on reinforcing effect. The curves of wave velocity after dynamic compaction present obvious catastrophe characteristics

which are enhanced with soil-rock ratio reduction

and its catastrophe segment is consistent with location of large size rock block. The curves of its wave velocity increasing proportion present vertical partitioning characteristics; and the soil-rock ratio influences more on reinforced thickness. The surrounding soil of large size rock block is strongly disturbed; and the wave velocity sharply reduced; especially located near the site surface or much large rock blocks. The reinforced depth is reduced with increasing buried depth of large size rock block which located in strong encryption zone

and it gets more shallow when its buried depth closer to the peak value of wave velocity.