Advanced analysis of road-slope stability in a brittle and faulted rockmass terrain by several techniques

Sengani, Fhatuwani; Muavhi, Nndanduleni; Mulenga, François K.

doi:10.1016/j.trgeo.2021.100545

Cited by 9 publications

(7 citation statements)

References 35 publications

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“…To apply the microtremor-based warning method on rockfall hazard assessment, the first rockfall warning is suggested to be issued when the extracted feature frequency of microtremor signal of a slope drops to the risk identification index, 1.5 Hz, or the signal energy concentrates at a low frequency of 1–6 Hz. After that, numerical analysis method 9 – 11 , 37 , 38 can be introduced to combine the climate and geological environment for investigating the rock landslide deformation and proposing the slope mitigation plan.…”

Section: Discussionmentioning

confidence: 99%

Spatiotemporal characteristics of ground microtremor in advance of rockfalls

Yang

Lee

Wang

2022

Sci Rep

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Identifying cliffs that are prone to fall and providing a sufficient lead time for rockfall warning are crucial steps in disaster risk reduction and preventive maintenance work, especially that led by local governments. However, existing rockfall warning systems provide uncertain rockfall location forecasting and short warning times because the deformation and cracking of unstable slopes are not sufficiently detected by sensors before the rock collapses. Here, we introduce ground microtremor signals for early rockfall forecasting and demonstrate that microtremor characteristics can be used to detect unstable rock wedges on slopes, quantitatively describe the stability of slopes and lengthen the lead time for rockfall warning. We show that the change in the energy of ground microtremors can be an early precursor of rockfall and that the signal frequency decreases with slope instability. This finding indicates that ground microtremor signals are remarkably sensitive to slope stability. We conclude that microtremor characteristics can be used as an appropriate slope stability index for early rockfall warning systems and predicting the spatiotemporal characteristics of rockfall hazards. This early warning method has the advantages of providing a long lead time and on-demand monitoring, while increasing slope stability accessibility and prefailure location detectability.

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Section: Discussionmentioning

confidence: 99%

Spatiotemporal characteristics of ground microtremor in advance of rockfalls

Yang

Lee

Wang

2022

Sci Rep

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“…These datasets were used to generate thematic map layers of eight groundwater controlling factors: slope angle, geomorphology, lithology, lineament density, drainage density, elevation, LULC, and rainfall. All map layers were converted to raster format and projected to UTM Zone 35S and then resampled to the same cell size of 30 × 30 m using ArcGIS software (Sengani et al 2021) and rainfall were classified into five classes using natural breaks method (Sengani et al 2021). Natural breaks classes are based on natural groupings inherent in the data (Jenks 1967).…”

Section: Geospatial Datamentioning

confidence: 99%

“…Generally, sedimentary rocks are characterized by high permeability and porosity compared to "hard" igneous and metamorphic. The geological map from GSSA was digitized to extract the lithological units characterizing the geology of the LRC using ArcGIS software (Sengani et al 2021). The area is characterized by four lithological units, that is, basalt, gneiss, marble and clastic sedimentary rock (Figure 4).…”

Section: Geologymentioning

confidence: 99%

“…In other words, because structural weaknesses increase water infiltration through linear boundaries, they are a major indicator of groundwater potential (Das 2019). For lineament extraction, lineament referring to linear/curvilinear feature of tectonic origin (Sengani et al 2021), the LINE algorithm of CATALYST Professional software was applied to Landsat band 4. This band was selected owing to visibility of linear features.…”

Section: Lineament Densitymentioning

confidence: 99%

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Using Geospatial Techniques and Analytic Hierarchy Process to Map Groundwater Potential Zones

Muavhi¹,

Mutoti

2022

Groundwater

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This study is conducted in Luvuvhu River Catchment (LRC) of South Africa, which has numerous major agricultural farms that are located in the upper catchment, especially in Levubu Valley. The significant irrigation developments in upper catchment have resulted in a decrease in the yield of surface water resources to such an extent that these resources struggle to meet domestic and industrial demand. The aim of this study is to delineate groundwater potential zones (GWPZ) as a way of establishing alternative water resources to relieve the overly stressed surface water resources. Various datasets are processed to extract groundwater controlling factors. Map layers of controlling factors are assigned weights according to their relative importance to groundwater occurrence using analytic hierarchy process and then integrated based on weighted sum analysis to generate GWPZ map. Rainfall infiltration breakthrough (RIB) and area under curve (AUC) are used to validate the GWPZ map. GWPZ map shows that lower catchment has very high groundwater potential covering about 409 km2. Nonetheless, about 50% of LRC spatially falls within high groundwater potential zone. Groundwater recharge, based on RIB for three boreholes, that is, A9N0007, A9N0008, and A9N0018 around Levubu Valley is estimated at 8.3, 15.4, and 16.2%, respectively. Boreholes A9N0018 and A9N0018 correspond to moderate to high groundwater potential zone, whereas A9N007 coincides with low to moderate zone. Considering the groundwater recharge estimates and associated potential zones, RIB results correspond well with GWPZ map. Also, an AUC, based on 26 boreholes, of 70.9% is achieved; thus, indicating a reliable model.

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“…To overcome this, probability methods are usually resorted to [10]. Most of these methods replace FoS values with a probability of failure as a measure of slope stability (see [11][12][13][14][15][16][17]), but the probability methods were also denoted to present some errors.…”

Section: Introductionmentioning

confidence: 99%

Establishing Reliable Slope Stability Hazard Map Based on GIS‐Based Tool in Conjunction with Finite Element Methods

Sengani

Muavhi

Mulenga

2022

Advances in Civil Engineering

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This paper describes the establishment of a slope stability hazard map based on a GIS-based tool in conjunction with the finite element method (FEM). In this regard, Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) images were modeled using the Weight of Evidence (WOE) technique. The previous simulation was therefore validated using visual observations and FEM (Phase 2D and SLIDE). The above techniques made it possible to develop and validate the reliable slope stability hazard map with the use of a case study. The results show that the established hazard map correlates very well with visual observation and stability assessment performed using FEM models. The map categorises slopes based on their susceptibility to failure; however, it has been discovered that most of the slopes that rated highly susceptible were located along or closer to geological features (faults) or streams and were at high elevations. Similarly, the SLIDE model has been utilised to perform the safety factor of the identified slope and the model has shown that those slopes were not stable. Furthermore, the influence of geological features was further studied using the Phase 2D model and it was discovered that the features contributed largely to the displacement of the rock mass with time, and as a result, instability was expected. The overall conclusion of the study is that the combination of geotechnical and GIS-based tools appeared to provide an insight in categorising the hazard of slopes located within mountainous terrain.

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Advanced analysis of road-slope stability in a brittle and faulted rockmass terrain by several techniques

Cited by 9 publications

References 35 publications

Spatiotemporal characteristics of ground microtremor in advance of rockfalls

Spatiotemporal characteristics of ground microtremor in advance of rockfalls

Using Geospatial Techniques and Analytic Hierarchy Process to Map Groundwater Potential Zones

Establishing Reliable Slope Stability Hazard Map Based on GIS‐Based Tool in Conjunction with Finite Element Methods

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