Experimental and numerical studies of three-layered unreinforced and geosynthetic-reinforced soil slopes

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TECHNICAL PAPER

Experimental and numerical studies of three‑layered unreinforced and geosynthetic‑reinforced soil slopes Kingshuk Jana1 · Suman Hazari1 · Sima Ghosh1  Received: 27 June 2020 / Accepted: 16 November 2020 © Springer Nature Switzerland AG 2020

Abstract This paper presents both experimental and numerical studies of three-layered reinforced soil slopes consisting of one sandy layer sandwiched between two cohesive–frictional soils. Geosynthetic reinforcements are provided at the interfaces. Smallscale shaking table tests are performed to evaluate different stability parameters like horizontal deformation, root-mean-square acceleration amplification factor, and crest deformation of the slope. Water content, base shaking acceleration, frequencies, and quantity and type of reinforcements are varied to perform the tests. The inclusion of reinforcements increases the strength of the slope enormously which is represented in the paper in terms of different parameters. Geogrid reinforcement is found to be better in comparison with geotextile reinforcement. To verify the results obtained from the present experimental study, a numerical model is developed using PLAXIS 2D and the acceptability of the study is discussed. Keywords  Layered slope · Cohesive–frictional soil · Sand · Shaking table · Geosynthetic reinforcement · PLAXIS 2D

Introduction Slopes are the exposed ground surface which stands at an angle with the horizontal. The stability of slope is one of the major concerns and trending research topics in geotechnical engineering for designing highway embankments, earth dams, etc. Slopes which are stable under static loading condition may not be stable under seismic loading due to the incorporation of extra added inertia force. In such situations, either the slope is to be flattened, embankment soil is to be replaced by higher strength soil, or the soil is to be reinforced by introducing reinforcements. The use of geosynthetics is one such method. The advantage of the use of geosynthetics is manyfold. In addition to the increase in strength of the slope soil, it also absorbs seismic energy and waves and transmits lesser energy to the next upper soil and so on. * Sima Ghosh [email protected] Kingshuk Jana [email protected] Suman Hazari [email protected] 1



Department of Civil Engineering, NIT Agartala, Agartala, India

The study of slope under static loading conditions is done by several researchers [1–4]. But to understand the response of slopes under seismic loading condition, Clough and Pirtz [5] have performed the first well-documented shaking table study on model rockfill dams and concluded that earth-fill dams are very much resistant to earthquake due to their flexible nature. Seed and Clough [6] have studied the earthquake-resistant dams and concluded that due to earthquake the upper portion of the slope undergoes settlement, whereas base soil undergoes sliding. Hong et al. [7] has performed shaking table tests on five-nailed model slopes and showed that the nails could improve the s