| 摘要 |
<p>The invention concerns an apparatus for drilling trenches (42) in the ground comprising a frame (14), a drilling assembly comprising a horizontal support plate (18) connected to the lower end of the frame, said plate supporting drilling tools (24, 26) arranged beneath said plate, said trench being filled with drilling mud. The plate (18) comprises at its periphery elastic sealing means (44) to produce at least partial tightness between said plate and the trench walls and means (40, 46', 48') to regulate the flow rates of the drilling mud from the part of the trench arranged above said plate towards the part of the trench beneath said plate and in the opposite direction, so that the pressure of the drilling mud beneath said plate is much less than the hydrostatic pressure exerted by the column of drilling mud in the trench above said plate, and the flow rate of the drilling mud extracted from the part of the trench beneath said plate is sufficient to enable removal of debris.</p> |
