Method for dewatering foundation pit by using bored cast-in-place pile

The invention discloses a method for dewatering a foundation pit by using a bored cast-in-place pile. The method comprises the following steps of: excavating a pile hole, hoisting a reinforcement cage in the pile hole, and fixing the reinforcement cage at an orifice by using a steel pipe or groove steel; hoisting water filtering pipes of which the bottoms are welded and sealed by steel plates to the orifice of the pipe hole, winding filter screens on the walls of the water filtering pipes, clamping upper openings of the water filtering pipes by using clamp plates, and arranging the clamp plates on the orifice of the pile hole; inserting all the water filtering pipes and well pipes into the pile hole sequentially section by section until a hole bottom is reached, wherein the length of each water filtering pipe is the same as an over-excavation depth; uniformly and continuously filling pisolith and fine sand to the periphery of outer walls of the well pipes in turn; putting the reinforcement cage down, and pouring concrete; and binding a cable on a water suction pipe by using a rope, lowering a water pump to a position which is 1 to 1.5m away from the hole bottom, hoisting the water pump by using a steel wire rope, and placing the water pump at a well mouth. By the method, a drill hole has two functions, the hole drilling construction of the well pipes is prevented, construction processes are reduced, and construction cost is reduced; and the method is particularly suitable for projects with pile formation difficulties or without dewatering conditions in the field.