عنوان مقاله [English]
Due to the procedure of increasing in axial load and speed on the existing railway tracks, need of improvement will be felt over the embankment. In this regard, one of the techniques is the use of geocell in the process of upgrading rail tracks. Therefore determination of the number of geocell's layers and alignment of their positions has a key role in this issue. Since influence of the number of layers and geocell's specifications on stability control and railway embankments' settlement are not specifically discussed in the technical literature, in this paper, by construction and loading of six embankments with m height in laboratory scale of , the influence of the number of geocell's layers with aperture size of $5\times5$ cm and height of 5 cm is studied on the stability of railway embankments. Modulus of elasticity of geocell by implementation of laboratory tensile test was obtained 70 MPa. Crown width and height of embankment in laboratory scale of 1:20, was considered 23 cm \& 50 cm with slope of 1:1 respectively. After construction of separated embankments with adjusting one layer, after that two layers, until five layers, an increasing monotonic load with speed of 1.5 mm/min over embankment's crown until failure was applied. The results showed that the bearing capacity and control settlement of embankments was proportional to the number of geocell layers, as this process would increase until the four layers geocell, rather than decreased in the fifth layers. Bearing \& settlement with four layers of geocell than embankment
without any geocell had an increasing of 86.6\% and a decreasing of 37\% over embankment's crown, respectively. In all tests circular sliding surface was superficial \& cutted the embankment at the top of slope that result in horizontal cracks at the levels of first \& second layers over the embankment's slope.