Experimental studies of reinforced clay bases of logging roads

The construction and operation of logging roads often takes place in unfavorable engineering and geological conditions. Very often, clayey soils with poor physical, mechanical and strength characteristics lie in the bases of logging roads. Improving these soil characteristics is an urgent task. For this purpose, reinforcement of soil bases with the help of geotextile materials is used. Most often, a horizontal arrangement of reinforcing geosynthetic layers is used. To date, there are a large number of studies of reinforced soil structures of logging roads, but they mainly concern the use of geosynthetics in sandy soils. Research in clayey soils is not enough. Therefore, experimental studies of the operation of reinforced foundations in clayey soils were carried out. The paper presents the results of stamp tests of clay soils reinforced with horizontal reinforcing layers. The studies were carried out in two stages. At the first stage, stamp model studies were performed, which made it possible to establish the optimal designs of reinforced clay bases. Based on the results of this stage, a single-layer horizontal reinforcing layer of geosynthetic material with a tensile rigidity of 2100 kN/m, an outer diameter equal to three stamp diameters, located at a depth equal to 0.25 stamp diameters was selected. The base soil was soft plastic clay. At the second stage, field stamping tests of the reinforced and non-reinforced clay base were performed. To study the stress-strain base, pressure sensors were selected to measure vertical normal stresses and a measuring system for their registration. Vertical displacements at various points of the active zone of soil foundations were evaluated by soil marks having a wire connection with deflection meters. The results of stamp tests showed that the bearing capacity of the reinforced base is 1.5 times higher than the bearing capacity of the unreinforced base. The deformation modulus of the reinforced base is 1.18 times higher than the unreinforced base in the load range from 0 to 100 kPa. The reinforcing layer is included in the work when the precipitation of the stamp is more than 30 mm. The stress-strain state of a reinforced base has significant differences from an unreinforced one. The reinforcing layer significantly reduces vertical stresses in the upper part of the active zone of the base, by an average of 22%/. The experimental stamp tests carried out made it possible to obtain a qualitative and quantitative picture of the operation of reinforced clay bases of logging roads.