Contacts Rus Eng SITE MENU Home - About the company - Articles - Assessment of strength and deformation characteristics of reinforced discrete layers Assessment of strength and deformation characteristics of reinforced discrete layers About company news Articles Geosynthetics are increasingly being used in a wide variety of areas of industrial, civil and transport construction. The scale of their application in the road industry is significantly increasing. Moreover, in recent years, the volume and range of geosynthetics produced by domestic manufacturers has been continuously increasing. Science helps to determine the level of efficiency of its use. According to the existing practice of designing and calculating road pavements (ODM 218.5.002–2008), it is accepted that the introduction of a geogrid into the pavement structure makes it possible to strengthen the pavement and prevent the interpenetration of materials of the contacting layers. Strengthening is achieved due to the joint work of the geogrid with a discrete base material or a transitional type coating, leading to blocking, that is, limiting the movement of individual grains of this material in the cells of the geogrid. It is believed that the formed composite layer “discrete (granular) material + geogrid” should have better mechanical properties, and above all, a higher deformation modulus than an unreinforced layer of discrete material. As you know, the modulus of deformation of a layer (structure) is determined from the results of compression tests or from the results of soil testing with a stamp when exposed to a static load in a pit or well. To ensure the reproducibility and preservation of the invariability of such factors as soil moisture, compaction technology, etc., the tests were carried out in laboratory conditions, taking into account the requirements of GOST 20276–99. When performing experimental studies, the modulus of the total base deformation was determined in a soil tray placed in a concrete cage with internal dimensions in the plan of 3.40 mx 2.00 m and a height (depth) of 1.40 m (Fig. 1). The soil flume was filled with fine sand with moisture equal to the optimum (14%), the angle of internal friction φ1 = 28 °, and the specific adhesion c1 = 0.4x10–2 MPa. The sand was placed in a tray in layers of 0.15 m. Each layer was compacted with a vibrating plate and a special manual rammer-stamp, dropped from a height of 0.40 m.In the process of laying the sand, its density in thickness and in plan was controlled by sampling with standard rings. The applied compaction technique made it possible to ensure a uniform density of the base, equal to ρ = 1.7 t / m 3. Above the sandy underlying layer, a crushed stone base (coating) was installed using the wedge method according to SNIP 3.06.03–85. The device of the crushed stone base (coating) was carried out in the following sequence: распределение основной фракции щебня (фракционированного щебеня 40–80 мм, марки 1000, 1 группы по ГОСТ 8267–93) и его предварительное уплотнение; распределение расклинивающего щебня (двухразовая расклинцовка: фракционированным щебнем 10–20 мм и 5–10 мм, марки 1000, 1 группы по ГОСТ 8267–93) с уплотнением каждой фракции. Толщина щебёночного слоя в уплотнённом состоянии составляла 20 см. After determining the total modulus of deformation on the surface of the crushed stone base, the layer was disassembled and the geogrid under study was placed in the place of contact between the crushed stone and sandy layers of the base (Fig. 2). The procedure for the arrangement of a discrete layer reinforced with a geogrid was carried out similarly to the sequence described above. As a reinforcing material, a geosynthetic material that has recently appeared on the market and is unfamiliar to the domestic road industry was used - a road reinforced geogrid RD (hereinafter referred to as RD). The physical and mechanical properties of the studied geosynthetic materials are presented in Table 1. The ribs of the geogrid are formed by six strands of spring wire, covered with a sheath of low pressure polyethylene (Fig. 3). To assess the influence of the structural and geometric parameters of the tested geogrid, samples of material with different mesh sizes (from 50 x50 mm to 100 x100 mm) were made, which influenced the tensile strength of the used material samples. The results of the performed experimental studies are shown in Fig. four. Studies have shown that the use of a geogrid of a road reinforced taxiway when reinforcing a discrete layer increases the total deformation modulus from 7% to 59%, depending on the design features of the material used. Based on the results of comparative tests, we can conclude that the use of the geogrid RD-45 75 x75 leads to a decrease in the total settlement of the stamp (with equal external influences) by 36%, and the resulting composite layer "discrete material + geogrid RD-45 75 x75" has a large by 59% modulus of total deformation, relative to the "traditional" (not reinforced) layer of discrete material. It should be noted that the effect obtained when reinforcing a discrete layer depends not only on the strength characteristics, but also on the structural and geometric parameters of the materials used (cell size). © 2017TechPolymer Group of Companies Leading manufacturer of geosynthetic materials Contact information Address: Krasnoyarsk, st. Matrosova, 10D Tel .: +7 (391) 269-54-64 info@texpolimer.ru website development