Abstract: A covering is applied onto the outer surface of a pile including a steel pipe or the like to surround a predetermined length thereof so as to reduce a frost heaving force or negative friction acting on the pile in a frigid area. The covering is closely adhered by an adhesion layer the like to the pile over a given length thereof. This given length is between 0.5 and 5 m. The covering member includes a smooth-surfaced plastic covering or elastic covering. A rugged surface covering may be provided below the smooth surfaced covering.

Abstract: The invention is to drive an article into an object or extract it therefrom by means of strain energy.The article is provided at its top with an elastic part having a reaction material for giving a tensile strain or a compressive strain to the elastic part via the reaction material in order to accumulate the strain energy in the elastic part.For carrying out the driving operation, the strain energy is abruptly released from the top of the elastic part, otherwise the compressive strain is abruptly released from the bottom of the elastic part. The strain energy is transformed into a kinetic energy and the article is struck on its head by this kinetic energy so that a compressive strain wave is generated in the article being driven.For carrying out the extracting operation, the compressive strain is abruptly released from the top of the elastic part, otherwise the tensile strain is abruptly released from the bottom of the elastic part.