A model test method for simulating the decrease in slope soil strength: application to an excavation slope

The numerical simulation-based strength reduction method has frequently been applied to analyze slope stability, showing that slope failure characteristics caused by the decrease in slope soil strength represent potential failure characteristics. This study aimed to develop a model test method for simulating the decrease in slope soil strength and applied this method to an excavation slope. A model material, composed of a high-strength substrate and a softening solution, which showed progressively decreasing strength, was developed. Then, a model slope constructed from the substrate was immersed in the softening solution to simulate the decrease in slope strength. Finally, an excavation slope was used to test the practical applicability of the developed method. The test results of the model slope indicate that the developed method enables the observation of the complete failure process caused by the decrease in slope strength, with a circular slip surface forming at 62 min 2 s of softening time; the location of the slip surface and the critical cohesion causing the slope failure generally agree with those from three limit equilibrium methods. The model test results of the excavation slope show that slope failure initiates near the toe at 53 min 36 s of softening time, followed by a series of retrogressive sliding failures that quickly occur; the location of the slip surface and the critical cohesion generally agree with the published information of the natural excavation slope.