Slope failures are essentially natural hazards that occur in many areas over the world. The effect of spacing of rock bolts on the stability of. In the models, the pattern of parallel deterministic joints was used in spacing of 2 meters. Decreases the number of rock bolts or dowels needed in a rock slope. In the models, the pattern of parallel deterministic joints was used in spacing of 2. By increasing the distance of rock bolts, the strength reduction factor srf has been decreased.
For the new facility, brenwal excavated more than 70,000m3 of rock. Design of overall slope angle and analysis of rock slope. Tunnel supported by rock bolts, excavated below slope. Slope failure, also referred to as mass wasting, is the downslope movement of rock debris and soil in response to gravitational stresses. Rock bolts jointed or sheared rock preventtreat sliding slabs concrete straps and bolts heavily jointed or soft rock prevent. Stability analysis of antidip bedding rock slopes locally. Determining rock bolt or anchor tension using a torque wrench. This engineer manual em provides guidance for analyzing the static stability of slopes of earth and rock fill dams, slopes of other types of embankments, excavated slopes, and natural slopes in soil and soft rock. The cuajone porphyry copper deposit is located on the western slopes of cordillera occidental, in the southern andes of peru. The types of movement, falls, slides, and flows, will be covered in this module. Chapter 15 rock slope design nysdot geotechnical page 155 january 14, 2015 design manual the detailed requirements for the design of rock cuts are provided in fhwahi99007, rock slopes reference manual, publication dated 1998. In the case of the anchorage of rockbolts in the natural pressure arch, the bolt length should be at least 1 m beyond the failure zone. Drainage of water is an effective method of increasing the stability of a slope.
Rock bolts are used to improve the stability and load bearing characteristics of a rock mass. Rock bolts rock boltingis using to transfer loads from the unstable zone at the rock face to the stronger. How does the slope angle play a role in slope stability. Determining rock bolt or anchor tension using a torque. The slope angle for each rock slope shall be selected based on the rock conditions at the site and the orientation of the discontinuities within the rock. Landslide can result either from rock failure or soil failure. To study the effect of length of rock bolts on the stability of rock slopes, the slopes in different dips such as 30, 45, 60, and 75 were modeled by phase2 software rocscience, 1999. For short term applications the bolts are generally left ungrouted. The effect of length of rock bolts on the stability of. For most rock cuts on highway slopes, the stresses in the rock are.
Passive support system requires block movement to develop bolt tension. Stability analysis of bolts reinforced rock jointed slope. Slope design at cuajone pit, peru s rk chiles rock mechanics team completed a study of the slope design at cuajone pit. Slope stability analysis using phase 2 request pdf. Rock slope design guide ohio department of transportation. The latter is not only cumbersome due to topological conditions, but also may. If the slope is made of highly fractured rock, rock bolts may be emplaced to hold the slope together and prevent failure. Fhwa nhi06088 6 slope stability soils and foundations volume i 6 3 december 2006 6. It is essential that the engineering geologist be intimately familiar with all of these methods because they provide ways of. These were related to problematic, geological and groundwater conditions involving weak rocks, unfavorable orientation of rock discontinuities and high groundwater levels.
Possible rightofway issues, debris containment, difficulty with drilling, and. Safety factor sf calculation for a slope a without tension crack b with a waterfilled tension crack. Dywidag dsi uk slope stabilization with rock bolts at. The setback gradient line measured from the toe of the slope, or channel assuming the location of the toe remains fixed with time. By increasing the length of rock bolts, the strength reduction factor srf has been increased. The slope stability analysis under the above conditions. Rock slope stability charles a kliche whether youre involved in surface mine design, surface mine production, construction, education, or regulation, this is an important book for your library. Only geotechnical practitioners experienced in collecting and analyzing rock structure data should perform these functions. 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. Failure modes in rock and soil slopes slope failure.
By increasing dip of slopes, the effect of length of rock bolts in the strength reduction factor srf is irregular. Drainage pipes could be inserted into the slope to more easily allow water to get out and avoid increases in fluid pressure, the possibility of liquefaction. Three major types of mass wasting are classified by the type of downslope movement. Network of bedding and crossjoints automatically created with the joint network option. In this study, a nonlinear method is adopted to analyze the stability of a weak rock slope reinforced. Stability calculation method of slope reinforced by. To study the performance of various rock bolts on the displacement of rock slopes, the slopes in different dips such as 15, 30, 45, 60, and 75 were modeled by phase2 software 1 for example, as fig. The impact of the number of strata layers within bolting range and pretension applied to bolts upon the stability of an opening was investigated using flac model. Use of passive anchors in increasing the stability safety factor of downstream slope of spillway in shahriar storage dam. The performance of various rock bolts on the stability of. Four statistical models for predicting optimum bolt supports using a minimum solid beam thickness were established, and based on these results, a design criterion was proposed. When rock bolts are used to reinforce a fractured rock mass, the rock bolts will be subjected to tension, shear and. It appears that the study in california was carried out during a time when there were no signifi. Introduction asuccessful rock slope stabilization program requires the integration of a number of interrelated activities, including geotechnical engineering as well as environmental and safety issues, construction methods and costs, and contracting procedures.
Water in a slope may come from two primary sources. Numerical analyses methods are the most common ones that are used for rock and soil slope analyses. Guide to geotechnical instruments, 20041124 2 choosing instrumentation. In the case of establishing an artificial pressure arch, appropriate bolt lengths are approximately 3 m in mine drifts and up to 7 m in largescale hydropower caverns. Geo slope international ltd, calgary, alberta, canada. When rock bolts are used to reinforce an antidip bedding rock slope, the position at which the reinforcement is applied has marked influence on the reinforcement effect. The low profile dcp rock bolt is a mechanical point anchored, pre tensioned, post groutable, low profile rock bolt with a grout injection head connection. Calculate the slope of this line as the ratio of tension in the rock bolt to correct torque, c. These analyses are often completed using slope stability charts and the dsara deterministic stability analysis for road access slope stability program. Provide shear support at the leading edge of a dipping rock block or slab using grouted steel bars. The effect of installation angle of rock bolts on the. The probabalistic sara stability analysis for road access program is still under development. Conclusion in this research that with aim to analysis the effect of spacing of rock bolts on the stability of rock slopes is done the following results are obtained.
Rock bolts are widely used to reinforce weak rock slope due to flexibility and effectiveness. Fe slope stability one of the major features of phase2 is finite element slope stability analysis using the shear strength reduction. Concrete straps and rock bolts are used to support loose or soft rock zones or to reduce the number of bolts. The factor of safety for rock slope stability shall be 1. To study the effect of installation angle of rock bolts on the stability of rock slopes, the slopes in different dips such as 30, 45, 60, and 75 were modeled by phase2 software rocscience, 1999. Typical applications include major civil engineering projects, such as tunnelling and slope stability, as well as lifeofproject infrastructure in. Monitoring loads on tiebacks or rock bolts and movements within a slope can provide an indication of the performance of a drainage system installed in a stabilized slope. Rock slope stability analysis utilization of advanced.
Study of effect of bolt anchorage parameters on rock slope. Popularly known as landslides, slope failures describe a wide variety of mechanisms that cause the outward or downward movement of slope forming materials like rock, soil or landfills. Bolt and cable lengths are highly variable and are compatible with a variety of rock types, structural characteristics, and strengths. The graphics and the pointandclick data input are also very good and makes the program very easy to use. Pdf on mar 19, 20, gaurav tiwari and others published study of effect of bolt anchorage parameters on rock slope stability by fem find, read and cite all the research you need on researchgate. Rock slope design guide page 21 section 200 geologic explorations, data collection and presentation 201 i.
Microsoft powerpoint 04 rock slope failure created date. Stability calculation model of frame supporting structure with prestressed anchor. How do friction and cohesion work together to stabilize slopes. These statistics demonstrate that water and geology are the most important influences in rock slope stability.
The software in general is very good and ties in well with the way we do things here. Today, there are several methods for slope stability analysis, each has its own advantages and disadvantages. Rock bolts are used to reinforce jointed rock masses or slabs on a sloping surface. Based on the failure mode of soil slope, it takes the soil, frame structure, and anchor rod rope interaction into consideration, and, according to the literature, for soil slopes and largescale rock slope structure circular sliding method is appropriate. Fhwahi99007 1998 which discusses geologic terms related to rock slope stability. By analyzing the change in slope failure mode, effects of the bolt head, spacing, inclination, and arrangement on the stability of the slope are investigated.
A technique for the calculation of slope stability based upon the assumption of a plane surface of failure through the toe of the slope has been proposed by culmann see taylor, 1948. Effect of rock bolts geometry of slope with tension crack in upper slope and its interaction with rock bolt. For more permanent applications or in rock in which corrosive groundwater is present, the space between the bolt and the rock can be filled with cement or resin grout. Cable anchors are used to reinforce thick rock masses. The fully grouted bolt is a convenient, effective, and economic technology for slope reinforcement. In the lecture part of this course we will discuss a variety of methods of analysis of slope stability and instability. A new nonlinear hoekbrown strength reduction method based on the characteristics of a jointed rock mass is proposed.
Methods for analysis of slope stability are described and are illustrated by examples in the appendixes. They are certainly major factors in cut slope stability and in. Use of passive anchors in increasing the stability safety. A new rock bolt design criterion and knowlwdgebased. Erik eberhardt university of british columbia geological engineeringearth and ocean sciences, ubc, 6339 stores rd. Rock anchors can be used to secure a single loosened block or to stabilize an entire rock slope that is affected by a prevalent rock structure. Dowels or anchor bars generally consist of deformed steel bars which are grouted into the rock.
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