Supporting construction technology of long steel casing, percussion and grabbing and rotary drilling bored pile in silt-rock fill layer

Using the impact holing method in reclamation areas with thick silt-rock fill layer will cause several consequences such as large disturbance in silt, reducing pile hole, large filling coefficient of concrete and so on, and it will badly affect the high-pressure jet grouting water-resisting curtain construction between the piles. Through comprehensive analysis of the geological conditions, the following construction technology is proposed: firstly, using vibratory hammer to put the long steel casing into the upper part silt-rock fill layer, and then using the grab-type drill to grab the rock in the steel casing; secondly, using rotary drilling hole below the steel casing. By means of this kind of supporting construction technology, the stability of hole wall, fast formation of hole, less mud and low cost to implement the green construction are ensured.