PSI - Issue 70

Md Azhar et al. / Procedia Structural Integrity 70 (2025) 199–206

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From the observation of the entire testing data, it is quite clear that the addition of the geotextile layer adds considerable maximum shear strength and axial strain and, at the same time, reduces the loss in shear strength after maximum. The increase in shear strength can also be justified by an increase in confining pressure. Thus, there is a clear positive correlation of maximum shear strength relative to number of geotextile layers and confining pressure applied. There is also a gain of peak strength with an increasing deviator stress. 3.2. Strength Ratio Strength ratio is presented as comparison of deviator stress of a reinforced specimen with a unreinforced specimen. Several studies indicate a positive correlation of strength ratio with axial strain and these two parameters with the number of reinforcing layers. In addition, a reduction in confining pressure is found to help in an increase of the strength ratio (Nguyen et al., 2013). The peak strength ratio is shown to vary with the geotextile layering and the respective confining pressure in Figure 6.

Fig 6. Effect of geotextile layers on peak strength ratio. The result obtained from study specified that inclusion of jute geotextile layer enhanced the soil shear strength significantly. Moreover, fig. 6 depicted that increase in confining pressure to specimen reduced the peak strength ratio slightly. Where the difference between peak strength ratio was maximum for reinforcement with 3 layers. The maximum increase in peak strength was observed due to increase in reinforcement layer at deviator stress of 0.5 kg/cm2. It can be opined from the results that the value of shear strength of soil increases due to increase in the no. of reinforcement layer. However, the strength ratio decreased for increase in deviator stress.

3.3. Failure Envelop

The failure envelope of specimen was a graphical representation of the shear strength of specimen under different stress conditions. This study aimed to assess the failure envelope of the specimen. The shear strength of a soil sample is determined by the shear stress on the failure plane when the specimen fails. Fig 7 represents the failure envelopes of sand that is both unreinforced and reinforced with geotextile, under varying levels of confining pressure.