Method for carrying out combined vacuum preloading treatment on soft foundation by gravel piles

The invention relates to a method for treating a soft foundation. The method comprises the following steps: (1) leveling a field, and laying a gravel cushion layer in a pretreatment area; (2) carrying out gravel pile construction; (3) laying a vacuumizing pipe network; (4) laying the gravel cushion layer to the designed elevation; (5) laying a sealing film with good elasticity on the leveled gravel cushion layer, digging a seal pit around a pre-reinforcement area, and burying the sealing film into the seal pit; (6) vacuumizing, and pumping water and gas. According to the method, a composite foundation is formed by adopting the gravel piles and a vacuum preloading method, so that the advantage of good water permeability of the gravel piles can be exerted to the utmost extent, and the drainage consolidation of the surrounding soil is accelerated; therefore, the construction period is effectively shortened, the bearing capacity and stability of the foundation are improved, the post-construction settlement is reduced, and the reinforcement depth reaches more than 30m.