Shear rate effect on the residual strength characteristics of saturated loess in naturally drained ring shear tests
<p>Residual shear strength of soils is an important soil parameter for assessing the stability of landslides. To investigate the effect of the shear rate on the residual shear strength of loessic soils, a series of naturally drained ring shear tests were carried out on loess from three landsli...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-10-01
|
| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | https://nhess.copernicus.org/articles/20/2843/2020/nhess-20-2843-2020.pdf |
| Summary: | <p>Residual shear strength of soils is an important soil parameter for
assessing the stability of landslides. To investigate the effect of the
shear rate on the residual shear strength of loessic soils, a series of
naturally drained ring shear tests were carried out on loess from three
landslides at two shear rates (0.1 and 1 mm min<span class="inline-formula"><sup>−1</sup></span>). Experimental
results showed that the shear displacement to achieve the residual stage for
specimens with higher shear rate was greater than that of the lower rate;
both the peak and residual friction coefficient became smaller with increase
in shear rate for each sample; at two shear rates, the residual friction
coefficients for all specimens under the lower normal stress were greater
than those under the higher normal stress. Moreover, specimens with almost
the same low fraction of clay (CF) showed a similar shear rate effect on the residual friction coefficient, with normal stress
increasing, whereas specimens with high CF (24 %) showed a contrasting
tendency, indicating that such an effect is closely associated with CF. The
test results revealed that the difference in the residual friction angle
<span class="inline-formula"><i>ϕ</i><sub>r</sub></span> at the two shear rates, <span class="inline-formula"><i>ϕ</i><sub>r</sub>(1)−<i>ϕ</i><sub>r</sub>(0.1)</span> under each normal stress level are either positive or negative values, of which the maximum magnitude is about 0.8<span class="inline-formula"><sup>∘</sup></span>. However, the difference <span class="inline-formula"><i>ϕ</i><sub>r</sub>(1)−<i>ϕ</i><sub>r</sub>(0.1)</span> determined under all normal stress levels was negative, which
indicates that the residual shear parameters reduced with the increasing of
the shear rate in the loess area. Such a negative shear rate effect on loess could
be attributed to a greater ability of clay particles in specimens to restore
broken bonds at low shear rates.</p> |
|---|---|
| ISSN: | 1561-8633 1684-9981 |