Geodiversity of surface karst features of geographical zones

The diversity of small, medium, and large solution features of zonal karsts and high mountain karsts is described here. It was taken into consideration how diversity changes according to the distance from the Equator in case of small, medium and large features of various zonal karsts and how it varies based on the distance from altitude in case of the karren features (small features) of high mountain karsts. It can be established that the diversity of karst features decreases according to the distance from the Equator (independent of the size of the features), while in high mountains the diversity of karren features first increases with altitude and then it decreases. The decrease of the diversity of medium and large features moving away from the Equator can be explained by the decrease of dissolution in­tensity. The diversity change of karren features shows a rela­tion with the diversity of the inclination of the bearing slope. Since on tropical karsts and in the medium elevated areas of high mountains (1600-2100 m) where bare slopes with large expansion and various slope inclination occur, the diversity of karren is great. On tropical karsts, slopes with diverse inclina­tion were created by karstification and in high mountains by glacial erosion.

Seismic bearing capacity of shallow strip footing embedded in slope resting on two-layered soil

In this paper, the limit equilibrium method with the pseudo-static approach is developed in the evaluation of the influence of slope on the bearing capacity of a shallow foundation. Particle swarm optimisation (PSO) technique is applied to optimise the solution. Minimum bearing capacity coefficients of shallow foundation near slopes are presented in the form of a design table for practical use in geotechnical engineering. It has been shown that the seismic bearing capacity coefficients reduce considerably with an increase in seismic coefficient. Be sides, the magnitude of bearing capacity coefficients decreases further with an increase in slope inclination.

Sensitivity Analysis of Anchored Slopes under Water Level Fluctuations: A Case Study of Cangjiang Bridge—Yingpan Slope in China

This paper presents an improved slope stability sensitivity analysis (ISSSA) model that takes anchoring factors into consideration in umbrella-anchored sand and clay slopes under reservoir water level fluctuation. The results of the ISSSA model show that the slope inclination and the layout density of anchors are the main controlling factors for sand slope stability under fluctuation of the water level, while the slope inclination and water head height are the main controlling factors for slope stability in the Cangjiang bridge—Yingpan slope of Yunnan province in China. Moreover, there is an optimum anchorage angle, in the range of 25–45 degrees, which has the greatest influence on slope stability. The fluctuation of the reservoir water level is an important factor that triggers slope instability; in particular, a sudden drop in the surface water level can easily lead to landslides; therefore, corresponding measures should be implemented in a timely manner in order to mitigate landslide disasters.

Assessing the effect of lithological setting, block characteristic and slope topography on the runout length of rockfalls in the Alps and on the La Réunion island

In high mountain regions, rockfalls are common processes, which transport different volumes of material and therefore endanger populated areas and infrastructure facilities. In four study areas within different lithological settings, LiDAR (light detection and ranging) data were acquired for a morphometric analysis of block sizes, block shapes and talus cone characteristics. Based on these high-resolution terrestrial laser scanning (TLS) data, the three axes of every block larger than 0.5 m in the referenced point cloud were measured. Block sizes and shapes are used to investigate them in the context of runout distances and to analyse the spatial distribution of blocks on the talus cone. We also investigate the influence of terrain parameters such as slope inclination, roughness and profile curvature (longitudinal profiles). Our study shows that the relation of block size within different lithological settings on runout length is complex, because we can neither confirm nor reject the theory of gravitational sorting. We also found that the block shape (axial ratio) does not have a simple influence on runout length, as it plays the role of a moderating parameter in two study sites (Gampenalm: GA, Dreitorspitze: DTS) while we could not confirm this for Piton de la Fournaise (PF) and Zwieselbach valley (ZBT). The derived roughness values show a clear difference between the four study sites. This also applies for the parameter of slope inclination and longitudinal profiles.

Accuracy of the UAV-Based DEM of Beach–Foredune Topography in Relation to Selected Morphometric Variables, Land Cover, and Multitemporal Sediment Budget

Recent developments in unmanned aerial vehicles (UAVs) have resulted in high-resolution digital elevation models (DEMs) of vulnerable coastal environments, including beach–foredune topography. If performed repetitively, they can offer an excellent tool to determine the spatial and temporal changes in the sediment budget, which may be required for proper land management. However, the quality of a UAV, slope parameters, and vegetation significantly influence DEM accuracy. The aim of this study is to compare precise GPS-RTK transects across a section of the South Baltic coast in Poland with those obtained from a DEM based on high-resolution and high-accuracy images obtained by a wind-resistant, high-quality fixed-wing UAV during beyond visual line of sight operation (BVLOS). Different land cover classes, slope inclination, and general curvature, as well as surface roughness, were taken into consideration as possible factors influencing the uncertainty. The study revealed that marram grass greatly affects the accuracy of the UAV-derived model and that the uncertainty of the UAV-derived DEM increases together with increasing slope inclination and, to a lesser degree, with increasing general slope curvature. We showed that sediment budget determinations with the use of a UAV-based DEM are correct only where grass cover is sparse, in our study, up to 20% of the area.

Spectral albedo measurements over snow-covered slopes: theory and slope effect corrections

Surface albedo is an essential variable to determine the Earth's surface energy budget, in particular for snow-covered areas where it is involved in one of the most powerful positive feedback loops of the climate system. In situ measurements of broadband and spectral albedo are therefore common. However they are subject to several artefacts. Here we investigate the sensitivity of spectral albedo measurements to surface slope, and we propose simple correction algorithms to retrieve the intrinsic albedo of a slope from measurements, as if it were flat. For this, we first derive the analytical equations relating albedo measured on a slope to intrinsic direct and diffuse albedo, the apportionment between diffuse and direct incoming radiation, and slope inclination and aspect. The theory accounts for two main slope effects. First, the slope affects the proportion of solar radiation intercepted by the surface relative to that intercepted by the upward-looking, horizontal, sensor. Second, the upward- and downward-looking sensors receive reduced radiation from the sky and the surface respectively and increased radiation from neighbouring terrain. Using this theory, we show that (i) slope has a significant effect on albedo (over 0.01) from as little as a ≈1∘ inclination, causing distortions of the albedo spectral shape; (ii) the first-order slope effect is sufficient to fully explain measured albedo up to ≈15∘, which we designate “small-slope approximation”; and (iii) for larger slopes, the theory depends on the neighbouring slope geometry and land cover, leading to much more complex equations. Next, we derive four correction methods from the small-slope approximation, to be used depending on whether (1) the slope inclination and orientation are known or not, (2) the snow surface is free of impurities or dirty, and (3) a single or a time series of albedo measurements is available. The methods applied to observations taken in the Alps on terrain with up to nearly 20∘ slopes prove the ability to recover intrinsic albedo with a typical accuracy of 0.03 or better. From this study, we derive two main recommendations for future field campaigns: first, sloping terrain requires more attention because it reduces the measurement accuracy of albedo even for almost invisible slopes (1–2∘). Second, while the correction of the slope effect is possible, it requires additional information such as the spectral diffuse and direction partitioning and if possible the actual slope inclination and aspect, especially when the absence of impurities can not be assumed.

P-Y Curves of Laterally Loaded Piles Near Earth Slopes

Design of piles under lateral loads using numerical analysis is a time-consuming process, requiring competent geotechnical engineers who can accurately model the soil profile and construction sequence. Therefore, most engineers have resorted to the p-y method that is a less time-consuming process in both the modeling and running time. Contrary to the numerical analysis method, the p-y method doesn’t require the burden of constructing a complicated 3D model. This method simply uses the relation between the soil resistance per unit length (p) and the lateral deformation (y) to deduce the straining actions on the pile, bending moment, and shear forces, which govern the structural design. However, the simplicity of this method comes with its shortcomings. The p-y method, for instance, cannot directly take into account the effect of earth slopes on the laterally loaded piles, and its results are somewhat approximate. A well-instrumented case study from the Caltrans site at Oregan State University is analyzed in this research. The studied case consists of a laterally loaded single vertical pile embedded in a cohesive soil layer near an earth slope of 2H:1V. A three dimensional numerical model of the case study is constructed, utilizing the finite element code, Plaxis 3D 2020. The p-y curves of the loaded piles were back-calculated from the numerical model using the elastic beam theory by performing the differentiation of the shear force acting on the pile along the full height of the earth slope. Normalized p-y curves were obtained to determine the p-multiplier, a factor that helps convert the p-y relation of a pile in leveled ground to that of a pile near earth slopes. Overall, it was found that the p-multiplier ranges between (0.4-0.8), (0.6-0.83), (0.8-0.95), and (0.98-1) for piles located at a distance of 0D, 2D, 4D, and 8D respectively from the crest of the earth slope, for various target depths. A parametric study for the effect of the distance of the pile from the crest of the slope, as well as the slope inclination, on the p-y curves was conducted. The curves were constructed for a single pile located at distances of 0D,2D,4D, and 8D from the crest of the earth slope. The performed study revealed that the p-multiplier, at a target depth of 1m, measured from the top of the pile, for the studied slope inclinations, ranges between (0.3-0.45) for the pile at a distance of 0D, (0.76-0.8) at a distance of 2D, (0.82-0.93) at a distance of 4D and (0.98-1) at a distance 8D. Analysis results showed that the effect of slope inclination diminishes when the pile is placed at a distance 8D from the crest or farther. These values can be implemented into p-y curves software, such as LPILE, to determine the straining actions required for design of a laterally loaded pile near sloping ground.

SISTEM VERTICAL DIGGING, BENCHES ATAU KOMBINASI? MANAKAH YANG DAPAT MEMBERIKAN TINGKAT KEBERHASILAN PALING TINGGI DALAM AKTIVITAS PENAMBANGAN KAPAL KERUK?

ABSTRAK Metode penambangan dengan kapal keruk (dredging) termasuk ke dalam metode penambangan tambang terbuka aquaeous, karena mekanismenya yang mirip dengan penambangan pada tambang terbuka, hanya saja kegiatan penggaliannya dilakukan di bawah permukaan air dengan alat penggalian berupa ember (bucket). PT. Timah Tbk sebagai salah satu perusahaan tambang yang memiliki ratusan Izin Usaha Pertambangan (IUP) Operasi Produksi untuk komoditas timah dan sebagai satu-satunya perusahaan yang memiliki beberapa unit kapal keruk, menggunakan armadanya dalam kegiatan penambangan endapan timah alluvial lepas pantai (offshore) di perairan Pulau Bangka dan Kepulauan Riau. Terdapat tiga jenis sistem penggalian pada operasional kapal keruk, yaitu sistem vertical digging, sistem benches dan sistem kombinasi. Sistem penggalian yang digunakan dapat mempengaruhi keberhasilan aktivitas penambangan pada kapal keruk yang dinilai berdasarkan parameter yaitu nilai Laju Pemindahan Tanah (LPT) dan kemiringan lereng (slope) yang dibentuk oleh proses penggalian. Analisis sistem penggalian bertujuan untuk melihat sistem penggalian manakah yang paling tepat untuk diterapkan pada kapal keruk sesuai dengan lokasi kerjanya. Data yang digunakan dalam analisis sistem penggalian merupakan data yang diperoleh langsung selama proses penggalian Kapal Keruk 21 Singkep 1 pada lokasi kerja Bulan Mei 2019. Data tersebut terdiri dari: nilai penekanan ladder, kecepatan naik turun ladder dan kecepatan tarik kawat. Kemudian pengolahan data dilakukan sehingga didapat nilai Laju Pemindahan Tanah (LPT) dan kemiringan lereng (slope) yang terbentuk dari proses penggalian menggunakan ketiga sistem penggalian yang ada. Analisis data dilakukan sehingga didapat poin-poin yang berkenaan dengan kelebihan dan kekurangan masing-masing sistem penggalian. Berdasarkan perbandingan tersebut maka dapat ditentukan sistem penggalian yang paling tepat untuk diterapkan pada Kapal Keruk 21 Singkep 1 sesuai dengan lokasi kerjanya adalah sistem penggalian kombinasi yang memiliki tingkat keberhasilan aktivitas penambangan tertinggi dengan nilai Laju Pemindahan Tanah (LPT) ) yang dapat mancapai target senilai 592,78 m3/jam dan kemiringan lereng (slope) akhir 45,83˚ yang sesuai dengan standar keamanan penambangan. Kata Kunci: Kapal Keruk, Sistem Penggalian, Laju Pemindahan Tanah, Kemiringan Lereng, ABSTRACT Mining using a dredger is an example of an aqueous open surface mining method. Due to its similarities of mining mechanism to a conventional open surface mining method, the difference being only the digging is carried out below the sea level (underwater) using a series of buckets. PT. Timah Tbk is a mining company that holds hundreds of mining concessions (Izin Usaha Pertambangan / IUP) for tin commodity and is the only company that owns several units of dredger, utilizing their fleet for mining operation of off-shore alluvial tin deposit in the waters of Bangka Island and Riau Archipelago. There are three known digging systems of dredger: vertical digging, benches and combination. These digging systems can affect the success of a dredger’s mining operation, which is assessed by following parameters: rate of material removal (Laju Pemindahan Tanah / LPT) and the inclination of slope formed by digging activities. The objective of this analysis on digging system is to find out which system should be applied depending on the dredger’s operational location. This analysis processes primary data obtained from digging activity of Kapal Keruk (dredger) 21 – Singkep 1 in May of 2019. The data consists of: ladder pressure, rate of ladder movement and pulling rate of wire. Thereafter, processing of data results in the value of rate of material removal and the slope inclination. Further analysis will disclose the benefits and also the shortcomings of each digging system. Based on acquired and processed data, the digging system that gives the highest rate of success of Kapal Keruk 21 – Singkep 1, which reflected on its rate of material removal of 592.78 m3/hour and final slope inclination of 45.83° (conform to the mining safety standard), is the combination system. Keywords: Dredger, Digging System, Rate of Material Removal, Slope Inclination

Paraglacial Cirque Headwall Instability - Regional Scale Assessment Of Preconditioning Factors

<p>Cirques are characteristic landforms in high alpine environments with flat cirque floors flanked by steep headwalls. From a rock-mechanical perspective, rock walls are assumed to adjust over time according to their internal rock mass strength, which is determined by a number of factors including e. g. intact rock strength and fracture system characteristics. However, temperatures permanently below freezing as well as glacier coverage keep cirque headwalls stabilised so that slope inclination can evolve during glaciation that is far beyond strength equilibrium. When cirque headwalls deglaciate, the relative importance of rock mass properties increases drastically as they precondition rock slope instability. Cataclinal headwalls, where major fracture sets dip out of the slope, are rated as unstable and usually respond rapidly to glacier retreat. Anaclinal headwalls with in-dipping fracture sets in contrast respond delayed and probably less drastically. To date, a systematic assessment of the predisposition of cirque headwalls for rock slope instability following deglaciation is lacking. We aim to tackle this lacking by a systematic regional analysis of predisposition factors using GIS tools.</p><p> </p><p>For the central Hohe Tauern Range, Austria, regional datasets are available for the most important preconditioning factors including topography (digital elevation model), geology (digital geological map), glacier extent (digital glacier inventory), and permafrost distribution (PERMAKART 3.0). We combined geomorphometric analyses with geotechnical data to locate and evaluate the sensitivity of glacier headwalls to rock slope instability using GIS and object-based analysis techniques.</p><p> </p><p>Our results show that a vast majority of the headwalls identified can be divided by a significant convexity in the slope profile curvature into a larger, upper and a lower, steeper headwall section (> 60°). The lower limit of the steeper section is marked by a significant concavity in the slope profile curvature, which is commonly known as the schrundline. Assuming that the convex transition between steeper and flatter headwall section constitutes the upper limit of enhanced headwall retreat e. g. by periglacial weathering inside the bergschrund, we further address this headwall section as the schrundwall.</p><p> </p><p>Geotechnical data (foliation dip and direction) has been digitalised and interpolated in a yet oversimplified manner, to distinguish  headwalls into cataclinal, anaclinal and orthoclinal slopes. Slope inclination and foliation dip has been interrelated to identify e. g. particularly sensitive overdip slopes. First results show that anaclinal and orthoclinal as well as cataclinal headwalls are quite common features in the study area. However, overdip slopes with steeply (30°-60°) outdipping foliation are almost exclusively found in schrundwall sections.</p><p> </p><p>The persistence of steep overdip schrundwalls may be related to permafrost occurrence, which is subject to further analysis. Our approach, applied to modeled subglacial topography, may be of great value to anticipate future paraglacial instabilities in glacier headwalls.</p>