The time-dependent behavior of soils has been investigated extensively using one-dimensional and triaxial tests. The phenomena associated with time effects in soils are creep, relaxation, strain rate and rearrangement effects. The engineering properties of soil are often improved significantly with the time elapse. The objective of this paper is to investigate the time-dependent effect on the shear strength parameters of sand–geosynthetic interface using large direct shear test apparatus. For this purpose, the geotextile layer has been adhered gently on a piece of wood with a thickness such that a half of the shear test box has been occupied. The other half of the box has been filled with the sand and the test has been performed. Three normal stresses of 30, 45, and 60 kPa have been applied in all tests. The shear stress has subsequently been applied in different times to the failure stage. In all tests, the shearing velocity has been kept the same. The results of these experiments show that the stiffness and friction angle of the dry sand– geotextile interface increases up to 12.6% and 3.9% at 720 minutes after the sample is poured in the mold.
For the past three decades, the use of geosynthetics to reinforce soil mass has been grown significantly. Nowadays, they are a well– accepted construction material. The use of reinforcement objects increases resisting forces in the soil mass through the tensile force provided by reinforcement elements, and consequently reducing the horizontal deformations and increasing the overall stability of the oil structure Therefore, the evaluation of soil-geosynthetic interface parameters, the interface friction angle, δ, and adhesion, ca, is important for the design of reinforced soil structures. The soil–geosynthetic interaction parameters are influenced by a) interaction mechanism between geomaterials and geosynthetics (pull-out or direct shear), b) physical and mechanical properties of geomaterials (density, grain shape and size, grain size distribution, water content, and plasticity of clayey soils), and c) mechanical properties (tensile peak strength), shape and geometry of geosynthetics. Although the shear strength of soil/geosynthetic interface has been investigated by conducting other tests, such as tilt table tests and torsional ring shear tests , the direct shear test is still the most common testing method.
Publisher : Sixth National Congress on Civil Engineering
By : Mahmoud Ghazavi , Javad Ghaffari
File Information: English Language/ 6 Page / size: 153 KB
سال : 1390
ناشر : ششمین کنـگره ملی مهنـدسی عمـران
کاری از : محمود غزوی، جواد غفاری
اطلاعات فایل : زبان انگلیسی / 6 صفحه / حجم : KB 153