Supporting and dewatering construction method during deep foundation pit excavation process

The invention discloses a supporting and dewatering construction method during a deep foundation pit excavation process. During a supporting process of deep foundation pit excavation, the upper part of a foundation pit is made of a soil-nailed wall, the lower part of the foundation pit is in the form of matching slope protection piles with waist beam supporting, corresponding layers of waist beams are arranged according to the depth of the foundation pit, and the waist beams are fixed among the slope protection piles by anchor cables and horizontally arranged; a high-pressure jet-grouting pile is arranged between each two adjacent slope protection piles, and the slope protection piles are matched with the high-pressure jet-grouting piles to form a waterproof curtain; and a light well-point dewatering system is arranged on the protection wall of lower supporting in the foundation pit. According to the supporting and dewatering construction method disclosed by the invention, dewatering governance during the fou