A self-sealing advanced
water pressure and
water flow detection device for a tunnel comprises an openable plugging device, a telescopic water guiding device and a
water pressure and
water flow measuring device which are connected sequentially. Before detection, a horizontal advanced drilling
machine is used for drilling a hole to the position required to be detected, and a soft stratum adopts casing pipes for wall protection. The device extends into the detection hole, a front-end casing
pipe abuts against the hole bottom, a central casing
pipe is pushed inwards continuously, and the front-end casing
pipe and a first-section casing pipe move relative to each other, so that a steel bracket drives a rubber piece to be stretched, and a
closed space is formed. A buckle on the first-section casing pipe is buckled in a groove of the front-end casing pipe, and a sealing device is in the working state. After pipe sections are full of water, a valve at the back end is closed, and
water pressure is measured by the aid of a water pressure gauge; the valve is opened, and the
water flow is measured by the aid of a water flow
machine; and
pore water pressure of a front-end stratum is measured by the aid of a most-front-end
pore water pressure sensor. After measurement is completed, the central casing pipe is pushed inwards continuously until the buckle is released from the groove, the steel bracket can be loosened after the central casing pipe is rotated, and the whole device is released.