Showing 3 results for Geosynthetic
Fariborz Dehghani, Hadi Shahir, Ali Ghanbari,
Volume 11, Issue 3 (1-2018)
Abstract
In the narrow geosynthetic-reinforced retaining walls a stable rear wall exists in a short distance and so there is no enough space to extend appropriate length of reinforcements. In this case, the probability of overturning of retaining wall increases especially when subjected to earthquake loading. To increase the stability of the wall, reinforcements may be connected to the stable rear surface. Alternative solution is the utilization of full-height cast in-place concrete facing in order to resist the earth pressure by combined actions of reinforcements pullout capacity and facing flexural rigidity. One of the main questions about this type of walls is the portion of earth pressure resisted by the facing. In this study, the seismic earth pressure of narrow geosynthetic-reinforced backfill on rigid facing was evaluated using limit equilibrium approach and horizontal slices method. The critical failure surface was assumed to extend linearly from the wall toe to the rear surface and then moves along the interface of the backfill and rear surface up to the backfill surface. The effects of various parameters such as wall aspect ratio have been investigated. The obtained results show that the applied soil pressure on wall facing will be increased with depth in the upper part of the wall according to the Mononobe-Okabe equation, but its pattern is inversed in the lower part of the wall and it decreases until it reaches to zero at the wall toe. The results of analyses indicate that the attracted soil thrust by the facing increases with lessening of backfill width.
Dr Mahmood Reza Abdi, Mr Mahdi Safdari Seh Gonbad,
Volume 12, Issue 5 (12-2018)
Abstract
One of the methods of increasing soil resistance against failure is soil reinforcement using geosynthetics. Soil-geosynthetic interactions are of great importance and are affected by friction and adhesion at their interface. Soil gradation, contact surface roughness and geotextile density are among the factors affecting soil-geotextiles interaction this study, to investigate the effects of these factors, large-scale direct shear tests have been conducted using a well and a poorly graded sand at a relative density of 80% reinforced with two geotextiles having different tensile strengths and mass per unit area. Samples were subjected to normal pressures of 12.5, 25 and 50kPa and sheared at a rate of 1 mm/min. Geotextile surface roughness was achieved by gluing two different single sized sand particles. Results show that increasing geotextile surface roughness increases shear strength at soil-geotextile interface. Geotextile tensile strength mobilization is shown to depend on soil grain size at the interface. The coarser and more angular the soil particles, the more effective the soil-reinforcement interactions. Geotextile tensile strength and its mass per unit area are shown to less important factors.
Mr. Seyed Ali Ghaffari, Prof. Amir Hamidi, Dr. Gholamhossein Tavakoli Mehrjardi,
Volume 14, Issue 5 (12-2020)
Abstract
This paper investigates response of triangular shell strip footings situated on the sandy slope. A series of reduced-scale plate load tests were conducted to cover different parameters including three shell footing types with different apex angles in addition to a flat footing, four different distances for strip footings from the crest of the slope namely “edge distance” and reinforcement status (unreinforced and geotextile-reinforced statuses). Bearing capacity of shell footings adjacent to crest of the slope, bearing capacity ratio, shell efficiency factor, influence of apex angle on settlement of footings and the mechanism of slope failure are discussed and evaluated. Also, empirical equations for determination of the maximum bearing capacity of triangular shell strip footings are suggested. As a whole, it has been observed that decrease of shell’s apex angle as good as increase of edge distance could significantly improve the bearing capacity. However, as the edge distance increases, the effect of apex angle on the bearing capacity got decreased. Also, it was found out that the beneficial effect of reinforcement on the bearing capacity decreased with increase of the edge distance. Furthermore, the efficiency of shell footings on bearing capacity was attenuated in reinforced slopes compared to the unreinforced status.
