STUDY OF THE PROCESS OF IMMERSION OF CONICAL CONCRETE BLOCKS INTO THE GROUND DURING THE CONSTRUCTION OF BUILDINGS

Abstract

In construction practice, hollow conical, seamlessly formed concrete blocks are used while erecting frame buildings of small number of floors. When such blocks are penetrated into the soil under them and around them, a dense zone is formed due to which their bearing capacity is significantly increased. The use of conical blocks allows to reduce the amount of earthwork and reduce concrete consumption, also the estimated cost of zero-cycle work. Target. Studies of the process of immersing conical concrete blocks into the ground and studying the features of the formation of a compacted zone formed in the soil base were carried out in the immediate vicinity of erected buildings and structures on construction sites, which were selected based on the characteristics of the geological structure and soil properties. To understand the qualitative patterns and physical essence of the process of immersing conical blocks, a specially designed stand was used, which made it possible to conduct experiments and analyze the physical aspects of this process in natural conditions. Results. It has been established that the compacted zone, which is formed as a result of the immersion of various elements in the soil in the form of a truncated cone (stamps, blocks, shells, etc.), has the shape of an ellipsoid of revolution, is heterogeneous in its structure and consists of several areas with different densities, geometric dimensions and shape. When immersing conical blocks whose area is close to 0,2....0,3 m2, the compacted zone is characterized by at least the presence of four areas with different densities. When blocks are immersed in sandy loam soils, the compacted zone becomes more flattened and elongated from the vertical axis of the ellipsoid compared to a base made of loam. In loess-like loams, soil compaction occurs predominantly downward under the base of the element and less away from the vertical axis. The dimensions of the densest region of the compacted zone, known as the core, are approximately the same in size in both cases and have a shape close to a sphere. It has been established that to increase the load-bearing capacity it is advisable to use cone-shaped nozzles. The optimal value of the angle at the top of the cone-shaped nozzle is: for dense soils 90...950, for subsidence 100...1100. Scientific novelty. For the first time, the physical essence of the process of immersing large-section building elements into the ground has been established, which lies in the peculiarities of the formation of a compacted zone depending on the depth of immersion, the design of the immersed element and soil conditions. When immersing conical blocks whose area is close to 0,2....0,3 m2, the compacted zone is characterized by at least the presence of four areas with different densities. Practical significance. The research results were used in the creation of industrial samples of equipment for immersing conical concrete blocks into the ground at the mechanical repair plant and UMS-2 system of JSC Dneprstroymekhanizatsiya and in the manufacture of the proposed conical concrete blocks at the reinforced concrete structures plant in the city of Dnepr.