A method for monitoring and controlling a downhole pressure of a well during formation of a borehole of a well is provided. The method can include monitoring a downhole pressure of a well during formation of a borehole of the well using a millimeter wave drilling apparatus including a waveguide configured for insertion into the borehole. The monitoring can include determining the downhole pressure. The downhole pressure can include an amount of pressure present at a bottom of the well. The method can also include determining a lithostatic pressure of rock surrounding the well at the bottom of the well. The method can further include controlling the downhole pressure relative to the lithostatic pressure of the rock surrounding the well at the bottom of the well. Related systems performing the methods are also provided.

The invention relates to a drilling tool for producing a bore in the ground, comprising a rotatably drivable basic body, a removal means at a lower end of the basic body for removing soil material, and at least one adjustable removal element, which is adjustable between a radially inner retraction position and a radially outer extension position in which the removal element protrudes radially outwards relative to the basic body in order to widen a bore diameter. According to the invention it is provided that for adjusting the removal element, an adjustment mechanism with a rotary member is provided, which is rotatable on the basic body about the drilling axis between a first rotary position and second rotary position, that at least one removal element is arranged on a pivot arm which is pivotable relative to the basic body between a first pivot position, in which the at least one removal element is in its retraction position, and a second pivot position, in which the at least one removal element is in its extension position, and that an actuating cam is provided on the rotary member and/or on the at least one pivot arm, by means of which actuating cam a rotary movement of the rotary member can be converted into a pivot movement of the at least one pivot arm.

Disclosed is a full-face shaft boring machine, a boring system and a boring method. The full-face shaft boring machine includes a cutterhead structure provided with an outer tapered surface structure protruding in a boring direction. The outer tapered surface structure surrounds an outer circumferential side of the rotation center of the cutterhead structure, and a radial cross section of the outer tapered surface structure gradually decreases in the boring direction; at least one receiving port for rock slag to pass through is formed at the taper top of the outer tapered surface structure and runs through the cutterhead structure in the boring direction; and a slag discharging assembly for discharging the rock slag is arranged on a side of the cutterhead structure away from the boring direction.