A slope is defined as a surface of which one end or side is. Calculate the factor of safety by determining and comparing. This engineer manual em provides guidance for analyzing the static stability of slopes of earth and rockfill dams, slopes of other types of embankments, excavated slopes, and natural slopes in soil and soft rock. Stability analysis is performed using slopew geostudio 2007. The stability condition of slopes is a subject of study and research in soil mechanics, geotechnical engineering and engineering geology. A case study of hwangryeong mountain, busan, korea sinhang kang 1, seungrae lee 2, and sungeun cho 3 1 school of urban and environmental engineering, ulsan national institute of science and technology, ulsan 44919, korea. In this section, the slope stability of excavations in various types of soil such as dry sand and gravel, dump. Assessment of groundwater conditions in the rock discontinuities, as is true of any slope, is also critical. Design and construction of soil slopes transportation research.
Extensive case studies throughout help illustrate the principles and techniques described, including a new examination of hurricane katrina failures, plus examples of soil and slope. Design of reinforcing piles to increase slope stability. The analysis involves computation of driving moment that is due to tangential component of weight of the slices, and the resisting moment that is due to shear strength of the soil along the trial slip surface. How do friction and cohesion work together to stabilize slopes. Although stability and movement are closely re lated, two different and distinct types of analyses are almost always used to evaluate them. Different types of slope failures and shape of their failure surfaces are discussed below. At critical locations where slope stability analysis is necessary, additional borings perpendicular to the cut should be provided in order to model existing geologic conditions for use in slope stability analysis. Pdf stability analysis of slope with different soil. The stability of aggregates is affected by soil texture, the predominant type of clay, extractable iron, and extractable cations, the amount and type of organic matter present, and the type and size of the microbial population. Slope stability analyses include static and dynamic, analytical or empirical methods to evaluate the. This chapter provides a basic outline of slope stability analysis. In the making of natural slopes, their is no contribution from our side. Slope stability is the primary means of quantitatively assessing the level of stability of a slope, done using a factor of safety.
The soil should be removed or retained as the condition is unstable. Fhwa nhi06088 6 slope stability soils and foundations volume i 6 3 december 2006 6. Originally, sixteen different products, including erosion control mats, mulches and tackifiers, were to be tested for this study. Shallow landslides are common when the soil mantle thickness ranges from 1 to 3 m. Soil testing for slope stability analysis slope stability. Using clear, concise language and practical examples, the book explains the practical aspects of geotechnical. We will introduce a few types of slope failure that are common in soils.
Osha will allow only rock to be cut vertically without worker protection. Stability analysis of a slope and finding critical slip surface. Slope failures depend on the soil type, soil stratification, groundwater, seepage, and the slope geometry. The stability analysis of the us slope and ds slope during construction are carried out by the method of slices. This balanced approach provides clear guidance for professionals in the field, while remaining comprehensive enough for use as a graduatelevel text. For this type of slope the soil properties for all identical depths below the surface are same. The steep slope in zone 1 necessitated safety ropes. Soil slope stability analysis using the friction circle.
Soil strength and slope stability, 2nd edition wiley. Slope stability analyses include static and dynamic, analytical or empirical methods to evaluate the stability of earth and rockfill dams. Stability of slopes in open excavation in different soil condition along with the factors that control slope stability in. Failures translational type failure of slope along weak zone of soil. Slope vegetation should be considered in all cases. Stability indications from surface features of slopes it is probably true that most assessments of the stability of a natural slope are based 80% or more on a to d above and less than 20% on analytical procedures. Soil quality information sheet soil quality indicators. Soil testing for slope stability analysis davecooper geotechnical 22 dec 02 03. Slope failure is the movement of mass on slope falls, slides, flows landslide. Soilrock transition hard residual soils to weathered rock are often excavated to between 1h. Factors affecting slope stability causes of slope failure. Slope stability analysis of unsaturated soil slopes based.
Chapter 4 slope stability home people at universiti. This book describes the stateoftheart methodology for evaluating and analyzing soil strength and the design and stabilization of slopes in soil. However, a saturated slope with parallel seepage will be about half as steep. The intent of section 4a is to introduce some basic definitions and concepts concerning stress and strengths in soil and rock. Allowable degree of risk of slipping which is determined based on the existing structures and new constructed buildings around the. Methods are also presented for checking the results of complex analyses and for presenting results of slope stability analyses. An overview on methods for slope stability analysis. An infinite slope stability model applicable for shallow landslide studies, equates resisting and driving forces in order to estimate a factor of safety,fs. Slope stability refers to the condition of inclined soil or rock slopes to withstand or undergo movement.
It is important to define any thin weak layers present, the presence of slickensides, etc. An earth slope or soil slope is an inclined surface of soil mass which can be either natural or manmade. The definitive guide to the critical issue of slope stability and safety soil strength and slope stability, second edition presents the latest thinking and techniques in the assessment of natural and manmade slopes, and the factors that cause them to survive or crumble. How does the slope angle play a role in slope stability. Embankment foundation problems involve the support of the embankment by natural soil. They are certainly major factors in cut slope stability and in. Translation failure occurs in the case of infinite slopes and here the failure surface is parallel. Extensive case studies throughout help illustrate the principles and techniques described, including a new examination of hurricane katrina failures, plus examples of soil and slope engineering from around the world. As a general rule, the bottom vertical height of the trench must not exceed 4 ft 1. This course is designed to supplement the theory and practice of soil mechanics that you learn in courses taught in civil engineering. Bvs viswanadham, department of civil engineering, iit. Changing slope geometry 3 cut slopes in soils thin soil cover over rock. The classification of the deposits shall be made based on the. The pile lengths ranged between 6 and 12 m, with the spacings varying between 3.
The number of equations of equilibrium available depends on the number of slices n and the number of equilibrium conditions that are used. Sliding mass travel long distance before coming to rest. Soil has shear strength, conventionally defined as friction and cohesion. First, stability charts for calculating the factors of safety fos with a slope angle of. The type of slope extending infinitely, or upto an extent whose boundaries are not well defined. Two types of slope stability problems occur in clays. Stability analysis should in clude consideration of. Subsequent benches may be up to a maximum of 5 ft 1. Soil strength and slope stability is the essential text for the critical assessment of natural and manmade slopes. Failure of a slope along a weak zone of soil is called a translational slide figure 16.
Stability of slopes in open excavation in different soil condition along with the factors that control slope stability in open excavation are discussed. Soil mechanics slope stability most trail construction should take place on slopes, not flat ground, and should proceed with the best practices of road construction engineering, yet depending on the user groups it wont have quite the same load requirements or factors of safety required for roads local requirements or regulations pending. Soil tends to fail in shear, these concepts directly govern slope failures. Pdf soil strength and slope stability semantic scholar. In reality, other than supersaturated soils or dry cohesionless sands and gravels, nearly all native dewatered soils will safely stand temporarily on a. In the making of natural slopes, thier is no contribution from our side. Designing a stable slope includes field investigation, laboratory investigation, and construction control. Increasing slope angle increases the driving force. Included are parameter definitions and common methods for quantifying them. Stability of slopes for excavations in different soil types. Some clays expand like an accordion as they absorb water. Stability analysis of slopes of earth dams soil engineering.
Using clear, concise language and practical examples, the book explains the practical aspects of geotechnical engineering as. Soil rock transition hard residual soils to weathered rock are often excavated to between 1h. Analysis of this type of failure is very complex and rarely done. Construction activities such as excavation of slopes and filling of slopes. Time during which the excavation is required to be open. Pdf stability analysis of slope with different soil types and its. Soil slope stability analysis 339 isfied for each and every slice, it is also satisfied for the entire mass. The failure of a mass of soil located beneath a slope is called as slide. Section 4a is followed by sections on soil weighrvolume relationships, soil and rock. Third, finding the correct method of stability analysis solves only part of the design problem. May 03, 2012 slope stability is affected by the following factors. The type of slope extending infinitely, or up to an extent whose boundaries are not well defined. Each soil and rock deposit shall be classified by a competent person as stable rock, type a, type b, or type c in accordance with the definitions set forth in 29 cfr 1926, subpart p, appendix a. Slope stability analysis has to be done for the proper functioning of infrastructure in hilly areas.
Soil bioengineering is a term that describes the use of living plant materials to build structures that provide slope support. Fhwa nhi06088 6 slope stability soils and foundations volume i 6 1 december 2006 chapter 6. Slope stability in strong rock 25 mpa based on classification from hungr et al. Soil strength and slope stability fills the gap in industry literature by providing practical information on the subject without including extraneous theory that may distract from the application.
These controlling factors are interactive, and the importance or effectiveness of each in controlling the type and degree of insta bility is dependent on local geologic, vegetative, and hydrologic conditions. For detailed design guidance and reference, geotechnical designers are directed to fhwanhi 05123 soil slope and embankment design. All subsequent benches must be below the maximum allowable slope for that soil type. Osha further make no distinction for bank heights between five and twenty feet high. Focus is on the principles of limit equilibrium analysis and the appropriate use of computer programs.
When the component of gravity is large enough, slope failure can occur, i. Pdf stability analysis of slope with different soil types. Slope stability analysis of unsaturated soil slopes based on the sitespeci. The purpose of this manual is to provide engineers and geologists involved in highway design and construction with a common understanding and approach to.
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