Shallow depth excavation system suitable for soft soil stratum and construction method

The invention discloses a shallow depth excavation system suitable for a soft soil stratum and a construction method. The shallow depth excavation system comprises a machine body, and a left arm, a right arm, a spraying unit and a conveying unit arranged on the machine body; the spraying unit is arranged at the middle part of the machine body; the conveying unit is arranged at the middle part of the machine body; an excavation lifting unit is arranged on the left arm; the right arm is provided with an anchor rod unit and a milling excavation unit; and each unit is modularly mounted on the left arm and the right arm of the machine body. The shallow depth excavation system further comprises an unearthing unit; a rail on the unearthing unit is arranged in a main line tunnel; a conveying belt is arranged in a transverse channel perpendicular to the main line tunnel; an electric transportation truck is arranged on the rail; and a grab is lifted in a port of a vertical shaft. The shallow depth excavation system and