This invention provides a vertical drainage structure to improve the
liquefaction resistance of driven gravel piles. The vertical drainage structure includes a grass mat layer laid at the bottom of the gravel
pile and above the
pile body, and a perforated steel
pipe inserted into the middle of the gravel
pile body. The grass mat layer is 8-12 cm thick, and the interval between adjacent grass mat
layers is 0.8-1.2 m. An
inverted U-shaped
pipe and a drainage hose are provided at the end of the perforated steel
pipe extending beyond the gravel pile body. This invention ensures a rapid drainage path while maintaining the strength of the gravel pile by using unevenly graded gravel. The grass mat layer, placed 1 m apart at the bottom and pile body, ensures smooth water passage while filtering soil particles, effectively preventing blockage of the drainage channel. The structure of this invention improves the drainage of gravel piles, avoids soil blockage of the drainage channel during construction, and ensures the
liquefaction resistance of the gravel pile. Its construction is simple, low-cost, and can be rapidly promoted.