Soil foundation reinforcement using hydraulic fracturing during horizontal drilling

Introduction. The development of technologies for strengthening the soil foundations of buildings and structures of various types is an urgent area in geotechnical construction. Methods that make it possible to create a network of reinforcing elements in a soil mass using various injection solutions are becoming particularly relevant. The aim is to scientifically substantiate and experimentally verify the effectiveness of a method combining the technology of horizontal directional drilling (HDD) and controlled hydraulic fracturing of a soil mass to create a network of injection inclusions in bulk soils.

Materials and methods. The methodology is based on a comprehensive field experiment. The design of a horizontal injector with rubber cuffs and the technology of its installation using HDD were developed and tested. The study included injection of cement mortar with a different water-cement ratio under controlled pressure, geodetic monitoring of the soil surface and subsequent excavation of the near-injection space to determine the morphology and geometry of cement inclusions.

Results. The nature of the formation of injection bodies in loose, unconsolidated soils in comparison with cohesive soils has been established, which is expressed in the formation of spherical volumetric bodies instead of flat lenses. A minor effect of the injection process on the ground surface has been recorded, which confirms its practical applicability.

Conclusions. The mechanisms of the distribution of mortar and the formation of cement inclusions in the soil are analyzed. It is shown that the proposed method makes it possible to purposefully create a network of point-hardened cement inclusions at the base. The technology has proven its fundamental validity and practical importance. The main advantages include the possibility of carrying out work without any interruption of production processes and eviction of tenants. The method is recommended for use in reinforcement under foundations, mainly shallow foundations, of both existing buildings and structures, and in new construction.

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