Abstract: A durable frost heave damage preventive structure of underground structures applicable easily and at low cost to many different kinds of underground structures. The frost heave damage preventive structure includes a plate-like reaction member (7) provided at the bottom of an underground structure (1) approximately in parallel to a freezing front in the ground.

Abstract: There is provided in a pressure feed pipe for feeding cement paste under pressure a wall panel assembly formed of a plurality of wall panels having collision surfaces and through holes and arranged at predetermined intervals. High-strength or superhigh-strength mortar or concrete is produced by kneading a designed amount of binder material comprising cement or cement and a pozzolan material together with a predetermined amount of water, passing this cement paste through the abovementioned pressure feed pipe to crush the cement balls contained in the cement paste and thus to homogenize the paste, and kneading the thus homogenized cement paste together with fine aggregate or fine and coarse aggregates.

Abstract: A method comprising interpenetrating a hollow casing into a relatively loose sand layer saturated with ground water, thereafter raising the casing while tamping crushed stones charged into the casing by a compaction rod disposed within the casing, and driving gravel drain piles while continuously performing the raising of the casing and the tamping of the crushed stones. After the casing has reached the predetermined depth and the charging of crushed stones has been confirmed an, amplitude of reaction is detected by a reaction detection device provided on the compaction rod or a load current measuring device of the compaction rod. The reaction value is compared with a set reaction value, and one or more factors (a raising speed of the casing, a period, an amplitude and an extreme end surface-height of the compaction rod for determining a compacting degree of a peripheral ground) are controlled in response to the compared value.

Abstract: A method for constructing continuous concrete walls free from water leakage under the ground, wherein upon hardening of the concrete of a preceding wall panel the space for the next succeeding wall panel is excavated and while placing a reinforcing steel cage in the space for the next succeeding wall panel, at least one injection pipe is inserted along with the steel cage; placing of concrete in this section Portland cement suspension is jetted at a high pressure from a nozzle of the injection pipe, which is pulled up as it is rotated, whereby clay or slime of bentonite or the like between the end faces of adjacent concrete walls is removed by the fracturing and agitating effect of the jet.

Abstract: A soil stabilizing method by using an air bubbled solidifying suspension or solution, which is jetted into the ground at a high pressure for the formation of solidified soil having homogeneous strength.