Method for monitoring external water pressure of lining

The invention relates to a method for monitoring the external water pressure of a lining. The method comprises the following steps of: 1) determining a water pressure monitoring area and a section according to the water leakage condition of an operating tunnel and the underground water distribution condition in a construction period; 2) determining the position of a water pressure monitoring point, and determining the arrangement position of the monitoring point and the size of a fiber grating osmometer device; 3) drilling at the arrangement position of the monitoring point by adopting a drilling device, and controlling a drill bit to be immersed into a rock-soil body outside the lining according to the thickness of the lining and the size of a drill rod; and 4) installing the fiber grating osmometer device, connecting an osmometer optical fiber lead with an acquisition instrument, and recording the external water pressure value after the acquired external water pressure value is stable, thereby completing mo