Construction method of deep foundation pit close to existing line

The invention relates to the technical field of building construction, in particular to a construction method of a deep foundation pit close to an existing line, which comprises the following steps: S1, completing the construction of a deep foundation pit supporting mechanism according to a design scheme; s2, a dewatering well is constructed in the deep foundation pit; s3, arranging a plurality of monitoring points on the roadbed of the existing line; s4, soil bodies in the double-row fender posts and the crown beam area are excavated in a layered and zoned mode; s5, when the deep foundation pit is excavated to the designed elevation of the waist beam and the inner support, concrete of the waist beam and the inner support is poured; s6, excavating the soil body below the waist beam and the inner support; and S7, foundation pit bottom sealing concrete is poured, and construction of the deep foundation pit close to the existing line is completed after the foundation pit bottom sealing concrete is cured to desig