Assessing slope failure in coal mining using kinematic analysis

Slope stability analysis is one of the important issues in open-pit mining. It is directly influences mining operation and cost. It also becomes a primary need to prevent slope failures that disturbing production activity. Failures in slope are controlled by factors such as slope dimension, geological structures, physical and mechanical properties of slope material, and the external forces acting on the slope. This paper presents the study results on the prediction of slope stability analysis by using kinematic analysis. The study was conducted to predict the potential slope failures that could occur at the selected mine site. The site was chosen on one of the locations of open pit coal mining PT. X in East Kalimantan. Some observation points are determined to show types of failure that can occur, such as plane and wedge failure. The results show that the potential failure of the planar type occurs in 8 locations while the wedge failure occurs in 7 locations. The potential failure occur in 5 observation points, i.e: Pit-1/OP-1, Pit-2/OP-1, Pit-3/OP-1, Pit-5/OP-1, Pit-5/OP-3. Other points are in stable condition because the plane’s direction is opposite the slope direction.

ROCK SLOPE SURFACE STABILITY ANALYSIS: A CASE STUDY ON HON LON ISLAND, KIEN HAI DISTRICT, KIEN GIANG PROVINCE, VIETNAM

The research aimed to study 24 rock slope surfaces along the road around Hon Lon Island, Kien Hai district, Kien Giang province, Vietnam. The analytical results have determined slope failure, wedge failure, and toppling, which occurred on almost slope surface and the average percentage of plane failure is the largest. The average percent of plane failure is 19.23%, the wedge failure is 15.35%, and the toppling fault is 6.73%. Besides, the analytical results have also identified the slope surfaces which can be the key blocks: ND-13, 18, 23, 25, 34, 37, 45, 51, 62, 63. The other analytical results show that the existence of key blocks at the rock slope surfaces in the N-S direction, dip to E at the survey locations: ND-13, 23, 63 and dip to W at the survey locations: ND-37, 45; in the NE-SW direction, dip to SE at the survey locations: ND-15, 62 and dip to NW at the survey locations: ND-18, 34; in the NW-SE direction, dip to SW at the survey location ND-51. These results have important significance to support for protecting slope surface safety.

Identifikasi potensi longsoran lereng pada kuari batugamping menggunakan analisis kinematika

Kestabilan lereng adalah faktor penting pada pekerjaan penambangan kuari karena berkaitan dengan keamanan dan keselamatan pekerja dan peralatan. Kestabilan lereng dipengaruhi oleh beberapa faktor di antaranya dimensi lereng, sifat fisik dan mekanik batuan, struktur geologi batuan serta faktor gaya luar yang bekerja pada lereng tersebut. Pada studi ini, kestabilan lereng diprediksi menggunakan analisis kinematika berdasarkan jenis gerakan material lereng, tanpa menganalisis gaya-gaya penyebab material lereng tersebut bergerak, sehingga yang diamati adalah fenomena struktur batuan berupa arah utama bidang diskontinuitas. Tujuannya adalah memprediksi kemungkinan arah dan terjadinya longsoran lereng. Faktor yang diperhitungkan hanya arah bidang diskontinuitas terhadap arah bidang lereng, sudut kemiringan bidang diskontinuitas dan sudut kemiringan bidang lereng. Hasil analisis menunjukkan beberapa lereng berpotensi longsor dengan tipe planar (plane failure) dan baji (wedge failure). Dari 10 lokasi pengukuran yang ditentukan secara acak, diketahui ada 4 lokasi berpotensi longsor planar 4 dan 5 lokasi longsor baji. Dalam hubungannya dengan arah dan kemiringan lereng, potensi tersebut terjadi di 4 lokasi pengukuran, sedangkan di lokasi lainnya diperkirakan aman karena tidak searah dengan bidang lereng. Kekar dan rekahan tidak menunjukkan arah dominan tertentu tetapi terdapat tendensi pada kwadran 2 dan 4.

Kinematic and Rock Mass Classification Assessment of Road Cut Slopes along with Karakoram Highway in Northern, Pakistan

Karakoram highway (K.K.H.) the only road link between two countries China and Pakistan. This road network is essential for two countries due to its strategic location and socioeconomic. The highway is more vulnerable due to landslide disasters, especially in rain and snow melting seasons, and different kinds of mass movement activities have occurred along K.K.H., such as rockfall, debris flow, and snow avalanche. The slope stability problems are widespread along with Karakorum (K.K.H.) between Besham city and the Dasu area because of the high seismic zone, rainfall, snow melting, and complex geology slope geometry, week, and adverse discontinuities sets. The detailed fieldwork was done along the Karakorum highway to minimize the risk of slope stability and for planning purposes in Besham to Dasu area and selected nine road-cut slopes. However, in these nine selected roadcut slopes, three slopes were already failed, four slopes are partially stable, and two slopes were stable. Both kinematic and empirical approaches are applied on all these nine road cut slopes and their discontinuities. The kinematic result has shown that all kinds of mode failure such as Toppling, Planar, and Wedge failure mode occurred in these slopes. The RMRb result has shown that all discounters lie in between fair to good rock. Both discrete and continuous (S.M.R.) results show that all discontinuity sets lie between the unstable, partially stable, and stable conditions.

An Open-Source Algorithm for 3D ROck Slope Kinematic Analysis (ROKA)

The Markland test is one of the most diffused and adopted methods of kinematic analysis for the identification of critical intersections of rock discontinuities that could generate rock failures. Traditionally, the kinematic analysis is based on the use of a stereographic approach that is able to identify the critical combination between the orientations of discontinuities and the rock wall. The recent improvements in the use of Digital Outcrop Models (DOMs) created the conditions for the development of a new automatized approach. We present ROck Slope Kinematic Analysis (ROKA) which is an open-source algorithm aimed at performing the Kinematic Analysis using the discontinuity measures collected onto a 3D DOM. The presented algorithm is able to make a local identification of the possible critical combination between the identified discontinuities and the orientation of the slope. Using this approach, the algorithm is able to identify on the slope the presence of critical combinations according to the traditional kinematic analysis of planar failure, flexural toppling, wedge failure, and direct toppling modes of failures and then visualize them on DOMs. In this way, the traditional approach is more effective and can be adopted for a more detailed analysis of large and complex areas.

Upper bound analysis of laterally loaded rigid monopiles in clay with linearly increasing strength

Monopiles supporting offshore wind farms are often subject to severe lateral environmental loads due to wind, waves, and currents. Previous studies reported various failure patterns for such rigid monopiles in clay; hence predicting lateral pile capacity of widely different magnitudes. In this study, both single-sided wedge failure mechanism involving passive soil failure only and two-sided wedge failure mechanism with simultaneous active and passive soil failures are proposed. The single wedge mechanism is found to be applicable if the soil behind the pile does not move together with pile resulting in a gap between the soil and the pile upon loading. On the other hand, the two-sided wedge is found appropriate for the soil behind the pile moves together with the pile upon loading. Two formulations are then derived from the two upper-bound failure mechanisms. The lateral pile capacity can be determined, and the corresponding failure mechanism identified based on the formulation which yields the lower capacity magnitude. In addition, the reliability of the formulations is verified against reported finite element methods as well as existing experimental and field test results.

An Analytical Method of Coulomb’s Active Earth Pressure Acting on Cohesion-Less Backfill Subject to Local Surcharge in Cold Regions

The traditional Coulomb’s earth pressure theory does not consider the effect of local surcharge on the lateral earth pressure and its critical failure angle. However, in practice, local surcharges commonly act on the surface of frozen backfill that is affected by freeze-thaw actions in cold regions and tend to affect the active thrust and its position. In paper, analytical solutions for estimating the active thrust, critical wedge failure angle, and action position subject to a local surcharge in cold regions are proposed. Herein, the simplified equivalent moment of surcharge is adopted on the premise of maintaining Coulomb’s earth pressure assumptions. The formula derivation is provided as a typical example to obtain the active thrust, critical wedge failure angle, and its position under a strip surcharge. Compared with previous approaches, the proposed solutions lead to easier evaluation of all indexes associated with Coulomb’s active earth pressure. Meanwhile, the expressions of Coulomb’s earth pressure under other types of nonuniform loading acting on the wall are discussed. In addition, sensitivity is performed to assess the effect of some main parameters. The results indicate that the dip angle of retaining wall-back and the friction angle of frozen backfill soil are two most significant indexes that influence the active thrust and its position.

Influences of Joint Persistence and Groundwater on Wedge Failure Potential of Jointed Rock Slope

<p>Joint persistence and groundwater are critical factors that influence the stability of rock slope. Persistence dominates the extent of pre-existing potential failure surfaces. Under certain conditions, slope instability may vary with time, as the propagation of existing joints leads to the development of fully persistence failure surfaces. At the same time, groundwater may travel through the fracture network and provides an external force to unstable rock masses, resulting in the damage of rock slope failure hard to predict. In general, when a rock slope consists of two or more sets of joints, the wedge failure often becomes the initial structurally controlled failure of a progressive large landslide. A classic case, which was occurred at a steep cut rock slope on 32.5k, Provincial Highway 7, Taiwan, had been completely recorded with UAV-surveys, field investigations and witness. The landslide first occurred on 13th May 2019 as a wedge failure with the magnitude of the volume of 892 m<sup>3</sup> and resulted in a large landslide on 29th July 2019 with the magnitude of the volume of 37234 m<sup>3</sup>, destroyed the protection measures and roads. According to the field investigation, groundwater was discovered flowing out from the line of intersection of persistence joints, which could be the main reason leads to the wedge failure and the progressive large rockslide. Hence, the couple mechanics-hydraulic behavior in a rock slope should be studied in more detail to mitigate such hazards.</p><p>In this study, sandbox model was applied to clarify the effects of the groundwater and joint friction on failures of single rock wedge. In addition, the software 3DEC, which is based on Distinct Element method, was carried out to extent the analysis conditions. The results of sandbox simulations were used to calibrate the performance of the numerical model, especially the coupled hydro-mechanical analysis. The stability of jointed rock slopes under different persistence and various water pressure conditions has been studied. It is believed that the study can enhance the way for stability analysis and monitoring of the potential failure of jointed rock slopes.</p><p>Keywords: Wedge failure; Joint persistence; Groundwater; Rock slope stability.</p><p> </p>

Kinematic Analysis of the Dam and Powerhouse Sites of the Baglihar Hydropower Project

The present study assesses the slope stability at the most significant Baglihar Dam for slope failure and landslides occurrences. The study comprises of twelve sites which were selected for detailed geotechnical investigation for assessment of potential slope failures using basic Rock Mass Rating (RMRb), Slope Mass Rating (SMR) and kinematic analysis techniques. The results show that even though the rocks are of fair quality but other factors including joint pattern and density caused by tectonic and anthropogenic activities have rendered three sites completely unstable, 8 sites are unstable and one site is stable. Moreover Nine sites are susceptible to wedge failure, six to topple and two to plane failure. The RMRb value varies from 45 to 55 and SMR value varies from 11 to 44. The thorough results and interpretation of work done is presented in this paper.