Engineering Technical Letter (ETL) (1999) engineers describes techniques for probabilistic analyses and their application to slope stability studies.
The methodology to evaluate liquefaction susceptibility will be presented in an Engineer Circular, Dynamic Analysis of corp Embankment Dams, which is still in draft form.
Technical Project Planning (TPP) manuals Process, eM 200-1-3, requirements for the engineers Preparation of Sampling and Analysis Plans.(5) Alteration of materials by faulting.(2) Past experience and judgement.Total unit weights are used for all formulations and examples presented in this manual.Successful design requires consistency in the design process.(3) Hydrostatic pressure computations for conditions of no flow.Prediction of the field behavior of clay shales should not be based solely on results of conventional laboratory tests, since they may be misleading, but on detailed geologic investigations and/or large-scale field tests.Even when computer programs are used for final analyses, charts are often useful for providing preliminary results quickly, and for providing an independent check on the results of the computer analyses.This, in turn, can cause additional movement, leading to further strain softening.All external loads imposed on the slope or ground surface should be represented in slope stability analyses, including loads imposed by water pressures, structures, surcharge loads, anchor forces, hawser forces, or other causes.The method is particularly useful for soil-structure interaction problems, in which structural members interact with a soil mass.Shear engineers strengths used in slope stability analyses should be selected with due consideration of factors such as sample disturbance, variability manuals in borrow materials, possible variations in compaction water content and density of fill materials, anisotropy, loading rate, creep effects, and possibly partial drainage.If materials are subject to strain softening, it cannot be assumed that a factor of safety greater than one based on peak shear strength implies stability, because deformations can cause local loss of strength, requiring mobilization of additional strength at other points along the slip.(1) The finite element method can be used to compute stresses manuals and displacements in earth structures. Undrained shear strengths can also be estimated using corp consolidated-undrained (CU, R) tests on specimens consolidated to appropriate stress conditions representative of field conditions; however, the R or total stress envelope and associated c and, from CU, R tests should not be used.
Although probabilistic techniques are not required for slope analysis or design, these methods allow the winavi designer to address issues beyond those that can be addressed by deterministic methods, and their use is encouraged.In viewer most practical problems, the factor of safety can be estimated with sufficient accuracy to estimate the developed shear game strength parameters (c D and D ) and the appropriate depth of the tension crack.Ductile stress-strain behavior is characteristic of most soft clays, loose sands, and clays compacted at water contents higher than optimum.A shear resistance lower than the peak, possibly as xbox low as the residual shear strength, should be used, based on the judgment of the designer.EM, survey Markers and Monumentations,.When large strains are required to develop shear strengths, surface movement measurement points force and piezometers should be installed to monitor movements and pore water pressures during construction, in case it becomes necessary to modify the cross section or the rate of fill placement.(2) Lithology, stratigraphy, and geologic details disclosed by borings and geologic interpretations.Explore and sample foundation and borrow sources.Where procedures for sampling, testing, or analysis are different from the procedures described in this manual, it is imperative to evaluate the effects of those differences.For soils with brittle stress-strain behavior (shear resistance decreases significantly as strain increases beyond the peak the peak shear resistance should not be used hotkey in evaluating slope stability, because of the possibility of progressive failure.Characterize the soil strength (see Appendix D).Such tensile stresses are almost hotkey always located along the upper portion of the shear surface, near the crest of the slope, and should be eliminated unless the soil possesses significant tensile strength because of cementing which will not diminish over time.Where zoned embankments or thin foundation layers overlying bedrock are involved, or where weak strata exist within a deposit, the failure surface may consist viewer of interconnected arcs and planes. Conventional analysis procedures (limit equilibrium).
(4) The depth of the crack should be selected to eliminate tensile stresses, but not compressive stresses.
EM, settlement Analysis, eM, bearing Capacity of Soils.
The design assumptions should be verified during construction.
When the corp of engineers manuals analysis has been completed, the following steps (not part of this manual) complete the design process:.
Several types of slope movements, including rockfalls, topples, lateral spreading, flows, and combinations of these, are not controlled by shear strength (Huang 1983).