Experimental investigation of the settlement behavior in clay soils with sand drain

With the increasing population and growing urbanization in our country, it is possible to build in problematic ground conditions by improving these soils. In particular, accelerating and reducing the consolidation settlements under the structure loads, which is one of the most important problems in saturated soft clay soils, with vertical drain applications have an important place among the soil improvement methods. In this study, the effects of sand drains, which are one of the traditional methods of vertical drains, were discussed on the settlement behavior of saturated low plasticity clay soil prepared in the laboratory. The clay soil used in the study was subjected to pre-consolidation stress of 50 kPa in a large sample tank with a side length of approximately 20 cm. Then, the deformations under uniform stresses of 100 kPa and 200 kPa applied with the loading frame designed within the scope of this work, were recorded depending on the time. In the experiments, firstly, the consolidation behavior of the saturated clay sample without sand drain was investigated. In the second group of experiments, the effect of sand drains with 4, 8, and 14, which are the diameter of 2 cm and height of about 15 cm, on the clay soils prepared under the same initial conditions were investigated. In the third group of experiments, the behavior difference of the sand drains prepared in a more dense form was discussed over the sand drain applications with 4 and 8. At the end of the consolidation tests, triaxial compression tests were performed on the samples, and the strength behaviors were interpreted after the improvement. As a result of the study, it has been determined that up to 46% differences between laboratory and theoretical total settlements. It has been understood that the smearing effect during drilling significantly affects the time-dependent settlement behavior. It has been observed that the laboratory model with 4 sand drains, which is without overlapping smear zones, is more effective in accelerating consolidation and reducing settlements. It has been observed that there is a decrease of approximately 17% in the total settlement amount of clay soils with dense sand drain compared to the loose ones.