Slope stabilization using driven piles mohamed ashour, ph. Whereas the existence of pipes has been documented in a good number of publications, their importance in the context of slope stability has not generally been appreciated. Methods are also presented for checking the results of complex analyses and for presenting results of slope stability analyses. While soil pipes are a form of natural drainage that could decrease slope failure susceptibility, the cavities produced may grow and weaken the overall strength of the subsurface, as well as. Benches are included every 4 to 10 meters of vertical height for slope stability and stormwater management. 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. 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. Soil pipes and slope stability in hong kong quarterly. The soil around and under the pipe and end section shall be hand tamped in 4 in. Results of numerical experiments using the simple method showed that 1 under the closed pipe condition, the flume. Another aspect of water that affects slope stability is fluid pressure. Slope deflection method problems with solutions pdf.
Slope stability analyses include static and dynamic, analytical or empirical methods to evaluate the stability of earth and rockfill dams, embankments. The number of equations of equilibrium available depends on the number of slices n and the. Driven, drilled, or micro piles can be installed to reduce the likelihood of slope failure or landslides or to prevent them. Slope stability causes of instability, analysis methods. Pdf soil pipes and slope stability in hong kong researchgate. A final cover system is constructed over the final slopes of the waste mass. To assess the possibility of landslides involving natural or existing engineered. A series of centrifuge model tests and numerical analyses were conducted to illustrate that instability of a fill slope inclined at approximately the internal friction angle of the soil can be triggered by confined groundwater flow due to soil layering in the fill slope. Current practice sliding granular soil mass stable soil.
Drainage pipes could be inserted into the slope to more easily allow water to get out and. Allowable degree of risk of slipping which is determined based on the existing structures and new constructed buildings around the. Publications are provided in portable document format pdf. Soil pipes and slope stability quarterly journal of. Changes in slope profile, which increases driving forces andor a decreases resisting forces. This technique is used for retaining walls and for slope stabilization. Reinforced soil walls, also called mechanically stabilised earth walls, are becoming increasingly popular as an economical and effective.
Soil strength and slope stability deere and patton1971, slope stability in residual soil length slope factors for applying the revised universal soil loss soil qualitysampling. Pipes partially filled with standing water will generate pore pressures in the surrounding soil matrix in proportion to the hydrostatic head achieved. Time during which the excavation is required to be open. Limitations readings require direct access to the top of the pipe. Numerical calculation of soil pipe flow and its effect on. Cut slope failure in soil may result from the following. Pdf soil strength and slope stability semantic scholar. Flume model tests with different soil pipe configurations, a no pipe, b closed pipe and c open pipe, were conducted to understand the influence of soil pipes on slope stability during rainfall. This book describes the stateoftheart methodology for evaluating and analyzing soil strength and the design and stabilization of slopes in soil. Soil pipes and slope stability quarterly journal of engineering. They are certainly major factors in cut slope stability and in.
In granular soils, the failure is mostly translational. Its behaviour is typical of that of composite materials and involves essentially two interaction mechanisms. The aims of slope stability analyses are to understand the development and form of natural slopes and the processes responsible for different natural features. Slope stability analysis has to be done for the proper functioning of infrastructure in hilly areas. Laboratory experiments on the influence of soil pipes on. Pipes partially filled with standing water will generate pore pressures in the. Cdotdtdr200210 sponsored by the colorado department of transportation. To assess the stability of slopes under shortterm often during construction and longterm conditions. Analyze and design ground anchors for slope stabilization using slope stability analysis program slope w. The stability analysis of the us slope and ds slope during construction are carried out by the method of slices. Design verification instruments are used to verify design assumptions and to check that performance is as predicted. Pond containment dike slope stability depends on construction materials as well as subsurface soil conditions below the embankments and ponds. Pdf introduction a recent paper by pierson 1983 provided sound evidence of the contribution of soil pipes to landslides. Slope stability evaluations by le and fe methods iii.
Evaluation of slope stabilization methods us 40 berthoud pass by michael banovich william skip outcalt report no. As soil and rock get buried deeper in the earth, the grains can rearrange themselves to form a more compact structure, but the pore water is constrained to occupy the same space. Additional embankment on top, steeper side slopes, or undercutting of the toe are. Writing for student and practicing geotechnical engineers, they consider such aspects as principles of soil mechanics, shear strengths of soil and municipal solid waste, methods for analyzing slope stability, analyses for rapid drawdown, seismic slope stability, factors of safety and reliability, presenting results of stability evaluations, and. Stability of slopes for excavations in different soil types. Soil slope stability analysis 339 isfied for each and every slice, it is also satisfied for the entire mass. How does the slope angle play a role in slope stability. Slope stability evaluations by limit equilibrium and. Details of slope stability analysis procedures are. Pdf soilroot interaction and effects on slope stability. The final cover system can be composed of natural clay soils, a combination soil synthetic membrane liner system, or soil cover only with vegetation.
Third, finding the correct method of stability analysis solves. How do friction and cohesion work together to stabilize slopes. Slope stability analysis should consider the cases of shortterm and long reinforced soil slopes and embankments for the purposes of this document, a reinforced slope is defined as a compacted fill embankment that incorporates the use of horizontally placed geosynthetic reinforcement to enhance the stability of the soil structure. The changes in the design procedure are those that remove references to allowable velocity. The stability of cut slopes in granular soil is highly influenced by the ground water level and friction angle.
A slope is an inclined boundary surface between air and the body of an earthwork such as highways, cut or fill, railway cut or fill, earth dams, levees and river training work. Minimum factors of safety levee slope stability 64 71. Ground water is a critical factor for the stability of granular soils as it reduces the effective stress resulting in a reduction of the soil shear strength. This chapter provides a basic outline of slope stability analysis. Soil root interaction and effects on slope stability analysis article pdf available in electronic journal of geotechnical engineering 17 january 2012 with 993 reads how we measure reads. 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 pipes and slope stability in hong kong citeseerx. Stability of slopes in open excavation in different soil condition along with the factors that control slope stability in open excavation are discussed.
Design and construction of soil slopes transportation research. Introduction a recent paper by pierson 1983 provided sound evidence of the contribution of soil pipes to landslides. The stability condition of slopes is a subject of study and research in soil mechanics, geotechnical engineering and engineering geology. Guidance on the collection, handling and storage of soil for the assessment o soil qualitysampling.
Focus is on the principles of limit equilibrium analysis and the appropriate use of computer programs. The analogue has shown that when a pipe is blocked or is a deadend passageway a closed pipe, the cavity can readily fill with water during rainstorms. Slope stability policy and procedure for pipeline design, construction and right of way maintenance revised 8232016 page 5 of 39 esrm slope stability 2. Stability analysis of slopes of earth dams soil engineering. Instrument data from the initial phase of a project. Flume model tests with different soil pipe configurations, a no pipe, b closed pipe and c open pipe, were conducted to understand the influence of soil pipes on slope stability. Ground anchors for slope stabilization draft 100% submission calculate allowable soil bearing pressure for concrete bearing elements for ground anchors using brinch hansens bearing capacity formula for inclined ground surface. Long pipes parallel to the fall line of the slope have the potential, when partially filled with water, of generating soil porewater pressures much greater than those generated by total saturation of the soil. Soil nailing is an insitu reinforcement technique by passive bars which can withsand tensile forces, shearing forces and bending moments. Rules of thumb and easy method of estimating slope stability geology and soils information needed from site or soils database check appropriate loading conditions seeps, rapid drawdown, fluctuating water levels, flows select values to input for. It also incorporates a permanent turf reinforcement mat trm laid over the slope surface to prevent erosion and promote vegetative growth. Fhwa nhi06088 6 slope stability soils and foundations volume i 6 3 december 2006 6.
Soil pipes usually enhance slope stability under rainfall events through their high water drainage ability, and pipe clogging by sediments is regarded as a risk for slope failure. The document was revised to add background information, examples, and a glossary and to expand the bibliography. This course is designed to supplement the theory and practice of soil mechanics that you learn in courses taught in civil engineering. The unit weight of the soil, cohesion of soil, internal fraction angle, slope angle, slope height, and pore pressure ration have been found to be the most important factors affecting on slope. Effect of air mobility in a soil pipe on water flow. The slope stability analysis is crucial in engineering practice to ensure the stability of structures and prevent loss of human life and money. Experimentation with a heleshaw viscousflow analogue apparatus has supported earlier suggestions, based on field evidence, that a causal link may exist between some soil pipes and slope failure. Attention is now focusing on pipes in hong kong as a major contributory factor to frequent landsliding. Instability caused by a seepage impediment in layered fill. Existence of soil pipes is reported in many collapsed slopes indicating their influences on landslide initiation. Slope stability verification manual deep excavation llc page 11 e. Pdf stability analysis of slope with different soil.
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