Earth pressure shield external air bag combined mud pressure balancing method

The invention discloses an earth pressure shield external air bag combined mud pressure balancing method. The earth pressure shield external air bag combined mud pressure balancing method comprises the steps that a mud pressure bin with an air bag or a combination of a plurality of air bags is connected with the top of a shield soil bin through a pipeline, in the shield tunneling process, the pipeline is unblocked all the time, the high compressibility or elasticity of the air bags is utilized, and mud is used as a transmission medium to keep in contact with the soil pressure in the soil bin to form a stable balance mode. By means of the mode, the conditions of ultrahigh pressure (the ultrahigh pressure can cause ground upheaval, slag outlet or shield tail spewing and shield tail sealing breakdown) or ultralow pressure (the ultralow pressure can cause stratum collapse and ground collapse) in the soil bin can be eliminated, the pressure of the soil bin is stabilized within a reasonable range, and micro-disturbance tunneling of the stratum around the tunnel is achieved.