DEWATERING AS A LEADING FACTOR IN THE DEVELOPMENT OF SUFFUSION UPON THE CONSTRUCTION OF DEEP FOUNDATIONS

The article considers the main technogenic factors leading to the development of mechanical suffusion during the construction and operation of buildings and structures with deep foundations. At a specific object, the dynamics of the development of an ascending suffusion process of a “volcanic” nature (“pseudovolcanic suffusion”) caused by systematic water drawdown and discontinuity of the upper aquiclude during construction work was studied. It is proved that the need for constant pumping groundwater entering the drainage system results rather from the violation of the upper aquiclude continuity, serving the soil foundation upon the construction of “retaining wall” and pile foundation than from the engineering defects in the constructed impervious screen. The research results made it possible for the first time to evaluate the possibilities of using two methods for determining the development of the ascending suffusion process in time; the method of measuring the duty cycles with a caliper and the method of filling the duty cycles with medium-sized sand until the formed volume is completely filled. Based on the laws of hydrodynamics, an attempt was made to determine the speed of the upward flow and the magnitude of the hydrophysical head. It is noted that the most important condition for the production of engineering surveys, when identifying interstratal high-pressure aquifers in the soils of the base, should be the mandatory plugging of exploration wells with high-quality concrete mortar in the range of depths of the bottom of the upper aquiclude and, at least, the design mark of the bottom of the pit, immediately after the completion of drilling.