In order to find out whether the existing tunnel lining design theory can better fit the actual stress characteristics of the strongly weathered soft rock shield tunnel and lining segment, a case study is conducted on the shield tunnel project in the northern extension section of Nanchang Metro Line 1, and the field test is carried out to monitor the external load and structural internal force of the segment for a long time. Meanwhile, a refined numerical model of the shield is established, and the mechanical characteristics of the segment are further explored and compared with the measured data. The results show that: (1) The most significant influence of the earth pressure and water pressure outside the ring of the pipe sheet is within five rings off the segment. The earth pressure at the bottom of the tunnel is less than that at the top of the tunnel, and the water pressure accounts for the majority of the total earth pressure. (2) The distribution mode of the vertical earth pressure on the segment is "large in the middle and small at both ends". The measured value near the vault is the largest, which

has a difference of nearly 20%, 30 % and 42% respectively compared with the calculated values of Terzaghi theory, Platts theory and tunnel specification method. It is more appropriate to calculate the vertical earth pressure of tunnel in strongly weathered soft rock stratum according to Terzaghi theory. (3) The internal force of the segment obtained by numerical simulation is in good agreement with the measured value. The overall bending moment of the segment exhibits a butterfly shape. The bending moment of the vault is slightly larger than that of the arch bottom.