Shear and compression strain development in sandy model slope under repeated rainfall

Sasahara, Katsuo; Sakai, Naoki

doi:10.1016/j.sandf.2017.08.021

Cited by 10 publications

(7 citation statements)

References 9 publications

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“…ese years, more researchers devoted themselves to the field of slope stability and failure mechanism study under rainfall, involving modelling test [15][16][17][18][19][20], numerical simulation [21][22][23][24], and field monitoring [25][26][27]. As investigated, slope safety is mostly influenced by rainfall, causing the surface erosion to the slopes by runoff [28][29][30][31][32], weakening the slope soil strength while percolating into the slope body [33][34][35][36][37], and reducing the effective stress in the slope soil while saturating the slope body [38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Experimental Assessments of Treating Effect on Retaining Walls for Loess Slopes under Long‐Term Rainfall

Liu

Zhou

et al. 2021

Advances in Civil Engineering

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Failures of treated slope occurring in China are at a continually increasing rate, and the huge number of treated loess slopes is calling for a postevaluation; however, no mature technique is in place. Based on an actual loess slope in Shaanxi Province treated by retaining wall, indoor geotechnical and model tests were conducted, revealing the rainwater infiltration process and pressure variations behind the wall, and the processes were then adopted to perform the postevaluation of the treated slope. The results proposed that effectual measures hence needed to be taken so as to avert rainwater infiltrating along the wall face and back or flowing through the wall body, which can soften the soil of the slope bottom. Although the wet front was developed by the rainfall process, it cannot be used as the boundary between saturated and unsaturated areas. Despite the peculiarly large soil pressure upon the wall back at the top layer, the soil pressure increases to a large value and then decreases with the depth. The model test results and investigation results were used to conduct the postevaluation of the prototype slope, which formed a postevaluation frame relevant to other slope postevaluations.

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Section: Introductionmentioning

confidence: 99%

Experimental Assessments of Treating Effect on Retaining Walls for Loess Slopes under Long‐Term Rainfall

Liu

Zhou

et al. 2021

Advances in Civil Engineering

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“…In particular, an accelerative increase in the displacement under a constant groundwater level could be recognized just prior to failure of a slope in some cases 8 . However, not only the accelerative increase but also the decelerative increase in the displacement were also observed under a constant GWL 6 . The increase in the displacement was significant at first, and then the ratio of the increase in the displacement decreased until the termination of the displacement in this case.…”

Section: Introductionmentioning

confidence: 81%

“…Many cases of the measurement of displacement and pore pressure in natural slopes or physical model slopes have been conducted to reveal the mechanism of an onset of a rainfall-induced landslide 1 – 8 . The displacement increased acceleratively with the increase in the groundwater level just prior to failure in some cases 1 , 2 , 4 , 7 , while it increased under a constant groundwater level in other cases 6 , 8 . The former cases are recognized as the shear displacement increase due to the increase in stress ratio according to the decrease in effective normal stress.…”

Section: Introductionmentioning

confidence: 94%

Development of the shear displacement of sandy soil due to absorption under constant shear stress for creep failure

Sasahara

2022

Sci Rep

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Measurement of the displacement and pore pressure in physical model slopes and natural slopes revealed that not only an accelerative increase up to failure but also a decelerative increase occurred in surface displacement under a constant groundwater level, which could be recognized as creep deformation under constant stress. The displacement increased significantly at first in both types, which made it difficult to evaluate whether the displacement developed to the point of failure at the start of the increase. It was necessary to find an indicator for evaluation as the first step of the prediction of an onset of slope failure. Measurement of shear and normal displacements of the sandy specimen in an inclined direct shear box with increasing water content was conducted to examine the indicator. The increase in the shear displacement was categorized into three types: the accelerative increase up to failure with increasing volumetric water content (VWC), the accelerative increase up to failure under constant VWC just prior to failure, and the decelerative increase under constant VWC. It was recognized that a constant VWC corresponded to constant suction from the experimental data. Shear displacement increased up to failure with the monotonic decrease in void ratio just prior to failure in the case of increasing VWC. The void ratio monotonically decreased under constant VWC in the case of shear displacement termination under constant VWC, while it significantly varied at first and then converged to a constant value just prior to failure in the case of shear displacement increase with constant VWC. The ultimate void ratio under the same stress conditions might have been unique. These facts revealed that the void ratio can be recognized as an indicator of the failure of specimens under creep deformation according to absorption. When the void ratio converges to a constant value under constant VWC, the shear displacement might increase up to failure, while the void ratio varying under constant VWC indicates that the shear displacement terminates before failure.

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“…While the displacement does not always increase monotonically with accelerating velocity, it shows a series of steep and gentle increase of the displacement with time (Fig. 1) in the slope under a series of rise and lowering of water level in a reservoir (Yao et al 2015;Yang et al 2019;Zhou et al 2018;Li et al 2018;Miao et al 2018) and repeated rainfall (Sasahara and Sakai 2017). The displacement can terminate its increase, and the slope does not fail in the case with decelerating velocity, while it increases up to the failure of the slope in the case with accelerating velocity at the final stage of the displacement as in Fig.…”

Section: Technical Notementioning

confidence: 98%

Development of the surface displacement during repeated rainfalls in sandy model slopes: condition for the increase of the displacement to failure

Sasahara

2022

Landslides

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It had been often reported that surface displacement showed an accelerating increase just prior to failure of a slope. Many methods for predicting failure time of a slope were proposed based on the modelling of the accelerating displacement just prior to failure. The mechanical condition which caused the accelerating displacement up to failure has been unclear until now. Measurement of 2-dimensional displacement was conducted on the model slopes under repeated rainfall, and measured data was analysed to examine the condition for accelerating surface displacement up to failure. Measured normal displacement varied with increasing surface displacement and did not converge to constant finally against the idea that the normal displacement approached to constant at steady state in direct shear condition on the slip surface parallel to the slope surface. It was supposed to be due to the difference in the direction of the slip surface to that of the slope surface. The angle α between the direction of slope surface and that of synthetic displacement on the surface, which synthesized the surface and normal displacements on the surface, was introduced to explain the variation of normal displacement with the increase of shear displacement on the slip surface in direct shear condition just prior to failure. The angle α varied at first with increasing surface displacement and converged to constant or quasi-constant just prior to failure on model slopes. It was recognized that the normal displacement converged to constant just prior to failure on the slip surface which was inclined against the slope surface. The angle α could be an indicator to judge whether the surface displacement increased significantly up to failure or not in the case that the slope failed under artificial rainfall.

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Shear and compression strain development in sandy model slope under repeated rainfall

Cited by 10 publications

References 9 publications

Experimental Assessments of Treating Effect on Retaining Walls for Loess Slopes under Long‐Term Rainfall

Experimental Assessments of Treating Effect on Retaining Walls for Loess Slopes under Long‐Term Rainfall

Development of the shear displacement of sandy soil due to absorption under constant shear stress for creep failure

Development of the surface displacement during repeated rainfalls in sandy model slopes: condition for the increase of the displacement to failure

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