scholarly journals Optimal profile for concave slopes under static and seismic conditions

2016 ◽  
Vol 53 (9) ◽  
pp. 1522-1532 ◽  
Author(s):  
Farshid Vahedifard ◽  
Shahriar Shahrokhabadi ◽  
Dov Leshchinsky

This study presents a methodology to determine the stability and optimal profile for slopes with concave cross section under static and seismic conditions. Concave profiles are observed in some natural slopes suggesting that such geometry is a more stable configuration. In this study, the profile of a concave slope was idealized by a circular arc defined by a single variable, the mid-chord offset (MCO). The proposed concave profile formulation was incorporated into a limit equilibrium–based log spiral slope stability method. Stability charts are presented to show the stability number, MCO, and mode of failure for homogeneous slopes corresponding to the most stable configuration under static and pseudostatic conditions. It is shown that concave profiles can significantly improve the stability of slopes. Under seismic conditions, the impact of concavity is most pronounced. Good agreement was demonstrated upon comparison of the results from the proposed method against those attended from a rigorous upper bound limit analysis. The proposed methodology, along with recent advances in construction technology, can be employed to use concave profiles in trenches, open mine excavations, earth retaining systems, and naturally cemented and stabilized soil slopes. The results presented provide a useful tool for preliminary evaluation for adopting such concave profiles in practice.

The design of open-cut slopes and embankments, foundations, levees, and earth-dam cross-sections is based primarily on stability considerations. There are many causes and types of earth instability. There are also many ways of analyzing the stability of slopes. The chapter considers the limit equilibrium approach, which aims essentially to determine a factor of safety, F, that would ensure a slope does not fail. The chapter considers the analysis of stability of infinite slopes based on translational type of failure and the analysis of finite slopes using the Swedish Method, Method of Slices, Bishop Simplified Method, Friction Circle Method, and the Translational Method. The solution of equations developed for the analysis of stability of slopes can be tedious and time consuming. A way of reducing the amount of calculation required in slope stability studies is by use of charts based on geometric similarity. The chapter discusses how Taylor (1948) and Janbu (1964) charts are used in stability analysis of slopes. Finally, the chapter discusses ways to reduce the risk of instability in slopes.


2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Yuxia Zhao ◽  
Jun Feng ◽  
Kangqi Liu ◽  
Hongwei Xu ◽  
Liqun Wang ◽  
...  

Due to the threat of global warming and the accelerated melting of glaciers and permafrost, the stability of slopes in permafrost regions has received an increasing amount of attention from scholars. However, research on the stability of soil-rock road cutting slopes in high-latitude and low-altitude permafrost regions of the Greater Khingan Mountains in the Inner Mongolia Autonomous Region has not been reported. For this reason, a study of the stability of a slope with a high ice content in section K105 + 600 to K105 + 700 of National Highway 332 is conducted. The slope is 20 m high and the slope angle is 45°, and the risk of landslides on this slope under the action of freeze-thaw erosion is very high. Because of this, field in situ monitoring, indoor freeze-thaw tests, thermal parameter tests, and ABAQUS numerical simulation models are used to study the stability of the slope. After collecting the continuous temperature, moisture, settlement, and slope deformation data, it was found that the slope was undergoing dynamic changes. The creep of shallow slopes increased with the number of freeze-thaw cycles. After approximately 150 freeze-thaw cycles, the slope safety factor was less than 1, which means that the slope had reached the limit equilibrium state. Therefore, freeze-thaw erosion greatly reduced the stability of the slope. Hence, the stability of the slope must be protected during its entire life cycle. This study provides a reference for the design and construction of road cutting slopes in the high-latitude and low-altitude permafrost regions of the Greater Khingan Mountains.


2013 ◽  
Vol 671-674 ◽  
pp. 180-185
Author(s):  
Qing Wang ◽  
Lei Hua Yao ◽  
Ning Zhang

Xiufengsi Landslide is an ancient landslide in Wushan County, Chongqing, China. Under natural condition, this landslide is stable. Due to the Three Gorges Reservoir, however, the water level in this region fluctuates within the range of [145 m, 175 m], periodically. Furthermore, an increasing number of residential quarters have been built on this landslide that also increase the possibility of occurrences of the landslide. Motivated by the government’s desire to take measures in control the landslide, we use two approaches to study the stability of this landslide. Under different computational conditions, the safety factors of the landslide are calculated by using limit equilibrium method and finite element method, respectively. Based on the comparison of the results, the stability of the landslide is analyzed more objectively and comprehensively. This work also lends insight into the landslide forecast.


1975 ◽  
Vol 12 (1) ◽  
pp. 146-152 ◽  
Author(s):  
W. F. Chen ◽  
N. Snitbhan ◽  
H. Y. Fang

The upper bound technique of limit analysis has been found to be very successful in analyzing the stability of cuttings in normally consolidated clays. However, most soils in their natural states exhibit some anisotropy with respect to shear strength, and some nonhomogeneity with respect to depth. It is difficult to obtain the solution based on the classical limit equilibrium analysis with the assumed noncircular failure plane with such soil properties included. This paper establishes an expression for the stability factor Ns, based on the upper bound technique of limit analysis which yields a close-formed solution for sections in which the following conditions are considered: (a) log-spiral failure-plane, through and below toe; (b) non-homogeneity; (c) anisotropy; and (d) general slope.


PROMINE ◽  
2018 ◽  
Vol 6 (2) ◽  
pp. 5-15
Author(s):  
Mersi Abadi ◽  
Arifudin Idrus ◽  
I Gede Budi Irawan Budi Irawan

Location of research situated in the village Karangdawa, district Margasari, Tegal Regency, Central Java. The location of the research is the exploration Licences PT. Indocement Tunggal Prakarsa Tbk., with commodities limestone. This research is aimed at mengetahuikualitas, batugampingserta reserves and resources geotechnical model based on the geological model. Geotechnical models also determined based on the model of rockmass used slope stability analysis as a model to design the mine pit. The methods used in this research include field work in the form of observation of outcrops of rocks and develop the sample, as well as laboratory analysis in the form of analysis of petrographic analysis and XRF using the sample surface, analysis of physical and mechanical properties of the rock mass classification, as well as rocks based on Geological Strenght Index (GSI) uses a secondary data in the form of core data drilling. Analysis of the stability of slopes in this study using the method of limit equilibrium (limit equilibrium method). Interpretation and correlation of data indicating that the drilling core location stratigraphic research is composed by three units of rock: limestone, batulempung, as well as sandstones. XRF analysis results and modeling geology suggests the quality of limestone meet cement raw material standards as to the amount of 13,180,000 tons of limestone resources. The geometry of the slope resulting from the analysis of the stability of slopes of which are: single slope height of 10 meters, the angle of slope of a single 80-degree slope, the slope of the overall 48 degrees, 50 degrees, 60 degrees, 54 degrees, the wide level of 8.31 meters. Limestone reserves estimation is determined only on the basis of consideration of the mine pit design and ultimate pit limit which is limited by the territory of IUP. Backup tertambang (mineable reserve) limestone amounted to 7,477,000 tonnes.


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