There is provided a guide assembly for guiding a cylindrical casing used in forming a sheathing wall in a ground. The guide assembly includes: a first guide-body having first inner and outer vertical faces and first top and bottom horizontal faces extending in a length-direction thereof; a second guide-body having second inner and outer vertical faces and top and bottom horizontal faces extending in a length-direction thereof, wherein the second inner face faces away the first inner face; at least one first coupling unit configured to couple the first and second guide-bodies to each other at the first and second top faces thereof; and at least one second coupling unit configured to couple the first and second guide-bodies to each other at lower positions of the first and second inner faces thereof.

A method for forming a drilled pile wall in ground using a drilling device having a reamer and flushing with a medium to remove drilling waste during drilling, and non-rotating pipe piles equipped with interlocks. A vertical 1 hole is drilled while simultaneously placing a pipe pile in the drill hole. At least one subsequent vertical hole is drilled hole in the ground side by side with the drill hole while simultaneously placing a subsequent pipe pile in the subsequent drill hole while the interlocks of the subsequent pipe pile interlock with interlocks of the pipe pile to guide the subsequent pipe pile into the drill hole. Reinforcements are installed in the drill holes, concrete is cast into each pipe pile to form a concrete pile, and at least some of the pipe piles are lifted at least partly out of the drill hole after the concrete has been cast, but before the concrete has bonded rigid to form a unified watertight pile wall.

The invention relates to a method for providing an underground barrier for a water flow. The method includes the steps of drilling in soil a number of parallel vertical holes; inserting pipe strings into the drilled holes, where each pipe string has a pipe string wall with a plurality of openings arranged distributed along the length of the pipe string; introducing injector means in each of the pipe strings; positioning the injector means at a plurality of discrete depths in the respective pipe string and aligned at each depth with at least one of the openings in the pipe string wall; and injecting at each discrete depth a sealing compound, such as sodium silicate, through the at least one aligned opening into the soil.

Apparatus and method for placement of a subterranean curtain below the face of the earth.