ASPECTS OF THE IMPROVEMENT OF FOUNDATION SOILS CONCERNING THE DEPTH VIBROTHRUSTING PUBLISHEDCristina Otilia Voicu, Monica Mirea, Carmen Aurelia Peptan
The paper presents the application of the technology of depth vibrothrusting improvement of the foundation ground for two high buildings: a Groundfloor+10 Floors tower type social-administrative building, placed in Timisoara, and a Basement+Groundfloor+9 Floors dwelling block, placed in Arad. The first researches and practical application of the experimental technology of depth vibrothrusting for low foundation grounds were realized at the former Roads and Foundation Department from the Politehnica University of Timisoara. The applied technology, the checking proceedinsg of the improvement quality and the behaviour in exploitation of the two presented buildings represent the novelty elements of the researches. The technology of depth vibrothrusting improvement of the foundation ground is very efficient in the case of the sandy loose grounds and sandy water saturated grounds. This technology consists of the introduction of equipment into the ground through vibration, on the width of the weak layer. The equipment consists of a rod and horizontal ribs, disposed in space. Because of the reduction of the friction, between the sand fragments (which can go up to 90%), these are rearranged in a settled state. The extraction of the equipment is resolved also by vibration, with a speed of 0,5 m / minute. Usually, the vibrothrusting equipment is placed in the corners of a grid consisting of equilateral triangles. For the two aforementioned buildings, the foundation grounds consists of partially saturated sand, which in a natural state falls into the category of grounds, which can be liquefied under seismic conditions. For the strengthening of the seismic protection of the other buildings, the depth compaction of the foundation ground was done through vibrothrusting. The verification of the compaction quality was done by dynamic cone penetration drilling, using the cone dynamic penetrometer. The very good behavior in exploitation of the two constructions underlines the efficiency of this method of strengthening the foundation ground. This method may be applied on special constructions from the agricultural domain, e.g. bunker, if the ground conditions mandate it.
vibrothrusting; vibrostinging; vibrogenerator; liquefying