Measurement of effective stress shear strength of rock. The borehole shear test bst and the rock borehole shear test rbst are unique among various insitu testing methods for field investigations in that they provide direct measurements of soil and rock shear strength parameters. Insitu borehole shear test and rock borehole shear test. Infiltration type slope stability method using nonlinear shear. Stability analyses of the slopes were carried out using the computer program slide 6 with the bishops method of analysis. Drainedstrength parameters from direct shear tests for. Appendix d discusses shear strength value selection. Maintaining borehole stability plays a very important role in the process of many oil well operations, since leakage and borehole collapse, which may occur in the drilling process, will cause significant economic loss gao et al. Borehole stability analysis accounting for anisotropies in. Undrained shear strength in the assessment of slope. Both volumes are very large electronic pdf files which may take several minutes to download.
Infiltration type slope stability method using nonlinear shear strength. Shear strength characterization of municipal solid waste. The table of contents from both volumes is shown below. For slope stability introduction of critical state soil mechanics. Atterberg limits testborehole shear testclay shaledeterministic slope analysisdirect shear testsgrain size analysisglacial tilllimit equilibrium methodsring shear testsslope stabilitytriaxial compression tests no restrictions. Borehole shear test the borehole shear test is sometimes referred to as the iowa borehole shear test, because it was originally developed by dr. The soils included cl and ml loess and glacial till, and ch clay shale. Soil slope stability investigation and analysis in iowa citeseerx. Type slope stability method is as shown in figure 11. A soil mapped as alluvial land in the uplands, which may actually be an inwash soil over glacial till and not a flood plain soil. This test method covers the determination of the direct shear and sliding friction strengths of intact specimens and specimens that contain a natural or artificial joint or discontinuity. The borehole shear test is a rapid and simple test that is similar to performing a laboratory direct shear test, except on the sidewalls of a borehole. Under the right conditions in clayey soils, the failure envelope from the bst may yield a friction angle and cohesion intercept in agreement with effective stress strength parameters determined from laboratory tests. His professional and research experiences include geotechnical site characterization, insitu test, slope stability, 2d and 3d effects in slope stability problems, shear strength reduction approach and effects of various methods in biplanar failure mechanisms.
Three iowa landslides analyzed on the basis of borehole shear test bst data are reported. They were mostly based on an approach that flows naturally from the definition of slope factor of safety, and is now commonly referred to as the shear strength reduction ssr technique. The slope stability assessment in this report is based on subsurface conditions in the boreholes, the observations during our site visits, and the slope profiles provided by the client. Therefore, the safe mud weight should be greater than the pore pressure gradient and shear failure.
Request pdf insitu borehole shear test and rock borehole shear test for slope. Borehole shear, in situ shear strength, shear tests, soil mechanics. Atterberg limits test borehole shear test clay shaledeterministic slope analysisdirect shear testsgrain size analysisglacial tilllimit equilibrium methodsring shear tests slope stability triaxial compression tests 18. In general, slope failures occur when the forces or rotational moments generated by the weight of the soil in a slope and external loads exceed the shear strength of the soil. However, an outwash terrace face may also be mapped palmyra 1520% slope. Two borehole tests were conducted after the failure incidence to investigate the cause of failure and their. The current practice of slope stability analysis for a municipal solid waste msw landfill usually overlooks the dependence of waste properties on the fill age or embedment depth. Paper open access infiltration type slope stability method. The slope stability equation and the applied shear strength equations are shown in figure 12. In the traditional deterministic approach to slope stability analysis and design, the shear strength, slope geometry, external loads, and pore water pressures are assigned specific unvarying values. Slope stability analysis geotechnical design manual m 4603 chapter 74 december 2006 slope stability analysis detailed assessment of the groundwater regime within and beneath the slope is also critical. Changes in shear strength of msw as a function of fill age were investigated by performing field and laboratory studies on the suzhou landfill in china.
Stress mlxt2 force per unit area in pounds per square foot psf, pounds per square inch psi, or kilopascals kpa 1 psi 1 144 psf 1 psi 6. Slope stability evaluations by limit equilibrium and. Insitu shear test for soil investigations iigm international. Suggested method for performing the borehole shear test. A borehole may be constructed for many different purposes, including the extraction of water, other liquids such as petroleum or gases such as natural gas, as part of a geotechnical investigation, environmental site assessment, mineral exploration, temperature measurement, as a pilot hole for installing. The borehole shear test is a rapid and simple test that is similar to performing a laboratory direct shear test, except on. Soil slope instability concerning highway infrastructure is an ongoing problem in iowa, as slope failures endanger public safety and continue to result in costly repair work. Characterization of slope failures is complicated, because the factors affecting slope stability can be difficult to discern and measure, particularly soil shear strength parameters. By definition, the factor of safety of a slope is the ratio of actual soil shear.
Figure 2 borehole location plan figure 3 assumed sections for slope stability analysis figure 4 longterm stable top of bank line no toe erosion by armouring the toe of bank figure 5 longterm stable top of bank line assuming a toe erosion setback allowance record of boreholes record of boreholes bh 1 to 15 expanation of borehole logs. Basically, a shear failure on the sides of a borehole is induced in order to obtain. Babs oyeneyin, in developments in petroleum science, 2015. Drilling fluids range from water to oil to complex chemical systems with properties designed for specific site conditions to aid the drilling process. Innovative solutions for slope stability reinforcement and. Procedure for performing direct shear and sliding friction. A palmyra soil located on an esker may be mapped palmyra 1520% slope. Soil slope stability investigation and analysis in iowa iowa state. Rock borehole shear test results from boring 10541. The iowa borehole shear test bst is an in situ device to rapidly determine a mohrcoulomb failure envelope in a borehole. Geotechnical investigation and slope stability assessment. Borehole stability analysis for underbalanced drilling article pdf available in journal of canadian petroleum technology 405.
Borehole stability modeling for drilling operations is primarily to create a safe mud weight mud pressure window such that the designed mud density will be high enough to ensure borehole stability and low enough to not fracture the formation i. Analysis of the vertical borehole stability in anisotropic. Use of inclinometers for geotechnical instrumentation on. Borehole stability an overview sciencedirect topics. Mohrcircles from cell test stress paths from triaxial test shear strength from lab tests. Slope stability studies fracture detection and analysis. The main reason for using stress variants is that the dp criterion is expressed in socalled stress. Atterberg limits testborehole shear testclay shaledeterministic slope analysisdirect shear testsgrain size analysisglacial tilllimit equilibrium methodsring shear testsslope stabilitytriaxial compression tests 18. The stability analysis was carried out for cross section at. Undrained shear strength in the assessment of slope stability of water defenses geotechnical lectures evening tu delft. This report presents the results of a geotechnical investigation and slope stability assessment carried out for the site. Volume 10, issue 1 march 1987 suggested method for performing the borehole shear test. A borehole shear test was performed in the weathered rock and a rock borehole shear test was performed in the intact rock. Backcalculations from bst friction angles measured in the shear zones consistently indicated that cohesion after sliding is near zero, suggesting that afterslip equilibrium must derive.
Borehole shear test in geotechnical investigations astm. When the slip circle is within the wetted zone then the suction at the base of all the slices is taken as zero and this will eliminate the second term in the four shear strength equations in figure 12. Backcalculations from bst friction angles measured in the shear zones consistently indicated that cohesion after sliding is near zero. Observations from borehole shear testing in unsaturated. Borehole stability technology includes chemical as well as mechanical methods to maintain a stable borehole, both during and after drilling. They are certainly major factors in cut slope stability and in.
Therefore, in order to increase economic benefit of well operation, gaining a full understanding of mechanical properties of rock becomes very important, since. Observations from borehole shear testing in unsaturated soil. Fhwa nhi06088 6 slope stability soils and foundations volume i 6 3 december 2006 6. Shear strength for slope stability analysis fattdad geotechnical 6 jun 17 11. Soil slope stability investigation and analysis in iowa. Chapter 6 engineering properties of soil and rock nysdot geotechnical page 66 june 17, 20 design manual 6.
The general use, operation, assumptions, and problems of the test are examined and examples of the interpretation of results are given. Because of the time, economics, and accuracy of this method, the technique of borehole shear should see increased use in future in situ geotechnical testing. Detailed pieziometric data at multiple locations and depths within and. Security classification of this report unclassified. The geotechnical investigation was carried out in two stages between september 20 and august 2014. The importance of reliable soil parameters in any geotechnical analysis has. Slopes in mountainous regions require cohesion 8 undrained short term slope failure in clay. Pdf borehole stability analysis for underbalanced drilling. Technical paper permeability test and slope stability analysis of municipal solid waste in jiangcungou landfill, shaanxi, china rong yang a, zengguang xu, junrui chaia,b, yuan qin, and yanlong li astate key laboratory base of ecohydraulic engineering in arid area, xi an university of technology, xian, shaanxi 710048, peoples republic of china. The borehole shear test bst and the rock borehole shear test rbst are unique among various insitu testing methods for field investigations in that they provide direct measurements of soil and. This paper reports a case history of bst and rbst measurements for the shales from a recent highway embankment slope project. Using the bst device, fifteen iowa slopes fourteen failures and one proposed slope were investigated and documented. The test can be conducted as a drained shear test, where. The field of slope stability encompasses the analysis of static and dynamic stability of slopes of earth and rockfill dams, slopes of other types of embankments, excavated slopes, and natural slopes in soil and soft rock.
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