Victor Mwango Bowa

This paper aims to understand how anchor cable force evolution laws can improve reinforcement designs. The self-developed weak plane sustained deterioration technology was conducted in the indoor test on the reinforced bedding rock slope containing a linear type weak plane. The force evolution laws of anchor cables with the weak plane sustained deterioration was studied. Furthermore, the theoretical equations were derived on the basis of the rigid assumption of the rockmass and the limit equilibrium method, and the equations have been verified to be reliable through comparison with the test results. The numerical simulations in different rockmass mechanical parameters reveal that the theoretical equations are suitable for hard rockmass. The results indicate that, with the weak plane sustained deterioration, the anchor cable axial forces increase gradually, and the axial force increase is inversely proportional to the length of the free sections. The findings could provide the theoretical guideline for the pre-stress safety reserves during the reinforcement designs of anchor cables in different positions of bedding rock slopes.

The interferometric synthetic aperture radar (InSAR) technique is widely adopted for detecting and monitoring landslides, but its effectiveness is often degraded in mountainous terrains, due to geometric distortions in the synthetic aperture radar (SAR) image input. To evaluate the terrain effect on the applicability of InSAR in landslide monitoring, a variety of visibility evaluation models have been developed, among which the R-index models are quite popular. In consideration of the poor performance of the existing R-index models in the passive layover region, this study presents an improved R-index model, in which a coefficient for improving the visibility evaluation in the far passive layover regions is incorporated. To demonstrate the applicability of the improved R-index model, the terrain visibility of SAR images in Fengjie, a county in the Three Gorges Reservoirs region, China, is studied. The effectiveness of the improved R-index model is demonstrated through comparing the visibility evaluation results with those obtained from the existing R-index models and P-NG method. Further, the effects of the line-of-sight (LOS) parameters of SAR images and the resolution of the digital elevation model (DEM) on the terrain visibility are discussed.

The contributions of the current analytical models on the prediction of the stability of the slope subjected to slide head toppling failure mechanisms, have always focused on the idealized geometry comprising regular blocks dipping into the slope face. Besides, the influence of groundwater and stabilizations from the lowermost block of the slope have been overlooked in the available literature. In this article, the analytical solutions that incorporates the kinematic mechanisms of the jointed rock slope under the influence of groundwater and stabilizing the lowermost block subjected to slide head toppling are derived based on the limit equilibrium. Furthermore, a real slide head toppling failure case history was studied to illustrate the effectiveness of the presented analytical solutions. The investigation results indicate that the presence of groundwater in the jointed rock slope, lowers the distributions of the normal and shear forces thereby inducing slide head toppling. Reinforcing the lowermost block of the slope, enhances the distributions of the normal and shear forces thus improving the stability of the jointed rock slope. The study results depict that the presented analytical solutions can provide an accurate and efficient stability analyses of the jointed rock slope subjected to slide head toppling failure mechanisms considering the presence of groundwater and stabilization effects.

In the traditional analytical models for evaluating block toppling failure mechanisms of the slope, a single weak plane angle is assumed, running from upper rock columns and daylighting on the slope face. However, for some physical rock slopes, the weak plane bounding the potential toppling blocks may be dipping at two diverse angles within the rock masses and may not daylight on the predictable point on the face of the slope due to varying characteristics of the weak plane. The mathematical technique for estimating the counter-tilted angle of the weak plane has been proposed and incorporated into the modified analytical technique for evaluating slope stability subjected to block toppling failure. The physical slope with pre-existing weak plane dipping at two diverse angles within the rock slope subjected to block toppling was analysed using the modified analytical technique and results were validated using the discrete element method. The obtained simulated failure mode zones are consistent with those obtained by the modified analytical technique. The influence of the relative counter-tilted angles of the weak plane on slopes stability was studied and the results show that, progressive increase in the counter-tilted angles of the weak plane lead to gradual increase in slope instability.