Discontinuous combined pile for reinforcing hard soil interlayer-containing soft soil foundation and construction method of discontinuous combined pile

The invention discloses a discontinuous combined pile for reinforcing a hard soil interlayer-containing soft soil foundation, wherein pile bodies in the foundation are discontinuous; the pile bodies are arranged in soft soil layers but are not arranged in hard soil layers; the pile bodies at the junctions of the soft soil layers and the hard soil layers are provided with expansion heads; the pile bodies are constructed by using a high-pressure rotary jet grouting process or a soil cement stirring process; and automatic control is performed in a pile forming process by using a computer program. The invention also discloses a construction method of the pile. The construction method comprises the following steps of: arranging a static sounding probe device below a pile driver; probing lateral resistance and end resistance of soil layers by using a probe to determine the property of the soil layers; transmitting a result to a program for controlling pile foundation construction; judging whether to construct a mixing pile or a high-pressure rotary jet grouting pile by the program; grouting to form the pile if the soil is soft soil; not grouting if the soil is hard soil; and constructing the expansion heads at the junctions of the soft soil layers and the hard soil layers so as to form the discontinuous combined pile form. The discontinuous combined pile is convenient to construct, is material-saving, can be suitable for soil layers of different properties and is an economical and high-efficiency high-grade pile form for treating the soft soil foundation.