Stability of rock slopes with in situ cavities

249A 914394 Application of revised design charts for steep reinforced slopes Jewell, R A Geotext Geomem VIO, N3. 1991, P203-233 After several years of application and extended research studies, previously published design charts (Jewell et al, 1974) have been revised. They now also consider vertical walls and are valid for the full range of polymer reinforcements, including grids and geotextiles. As well as greater flexibility in design, savings in reinforcement quantity of the order of 20-30*/0 are possible. The theoretical basis is outlined, design parameters and safety factors clearly defined, and practical applications illustrated using worked examples. 914395 Finite element analysis of progressive failure in long slopes Wiberg, N E; Koponen, M; Runesson, K lnt J Num Anal l~leth Geomech VI4, N9, Dec 1990, P599612 The case of a long natural clay slope separated from the bedrock by a weak silt layer or shear zone is discussed. The clay is elastic-perfectly plastic, the weak layer may be elastic-plastic strain softening. One dimensional finite element analysis is used to study possibility of progressive failure. Critical surface load, critical disturbance, and critical length of slope are examined. Effects of different residual strengths of the weak layer, end disturbance, or pore pressure change in the weak layer can be investigated. Whether failure will occur and which form it will take may be predicted. 914396 Embankment reliability versus factor of safety: before and after slide repair. Application brief Wolff, T F int J Num Anal Meth Geomech VI5. NI, Jan 1991, P41-50 Probabilistic slope stability analyses incorporate more information on input variables than do deterministic analyses, and therefore more information is contained in the results. A general probabilistic analysis (Wolff and Harr) which allows analysis of embankment sections with multiple soil zones is presented. It is applied to demonstrate the low level of reliability of an embankment before a slide occurred and the increase in reliability obtained by repair with construction of a rock toe berm. 914397 Influence of macropores on debris flow initiation McDonnell, J J Q J Engng Geoi V23, N4, 1990, P325-331 A debris flow from an instrumented catchment in New Zealand has been studied. Tensiometric and throughflow data from adjacent areas show vertical cracks which conduct water to the soil-bedrock interface far faster than the soil matrix. This flow is rapidly transmitted downslope by a well developed system of pipes. Under extreme rainfall conditions, the flow capacity of the pipes may be exceeded by rate of supply by the vertical cracks. Pore pressure buildup at the soil rock interface results,which may trigger slope failure. 914398 Force distribution among slope-protection structure pile rows Ginzburg, L K; Kovai, V E; Lapkin, V B; Vaskovskaya, V S Soil Mech Found Engng V27, N2, March-April 1990, P52-58 Model tests were carried out on slope retention structures consisting of 2, 3, or 4 rows of piles. In some tests the pile heads were free, in others they were joined by rigid pile caps. Distribution of pressure among the pile rows was measured as load

on the displaced soil mass was increased. Results are presented and discussed. It is recommended that for the capped structures the load may, for design purposes, be considered equally shared between rows, and fractional distribution values are given for the case of uncapped piles.

914399 Stability of rock slopes with in situ cavities Rogers, G K; Haycocks, C Proc 1989 Multinational Conference on Mine Planning and Design, Lexington,23-26 May 1989 P173-179. Publ Lexington: OES Publications, 1989 As quarries, open pit mines, and other surface excavations are worked progressively deeper, the potential detrimental effect of in situ cavities upon slope stability is of increasing importance for a safe yet feasible design. Types of in situ cavities are defined, and case histories along with observations from field investigations are utilized in illustrating problems encountered when dealing with insitu cavities. Planning, analysis, and design recommendations are made.

914400 Rapid design assessments from slope stability calculation results Bromhead, E N; Harris, A J Proc International Symposium on Computer and Physical Modelling in Geotechnical Engineering, Bangkok, 3-6 December 1986 P3-12. Publ Rotterdam; A A Balkema, 1989 PCs are now common in design offices, and slope stability calculations have become routine. Application of simple but useful procedures which can save time by eliminating many fruitless searching analyses is described. The simple principles to be considered are evaluation of average normal and shear effective stresses, finding shear strength parameters for F = I, determining the feasibility of drainage, location of counterweight embankments, evaluating stresses on retaining walls and anchor loads, assessment of critical seismic acceleration from static factors (and vice versa), and finding critical slip circles.

914401 Application of an inter-active computer-aided probabilistic slope stability assessment for embankments on soft Bangkok clay Bergado, D T; Chang, J C Proc International Symposium on Computer and Physical Modelling in Geotechnical Engineering, Bangkok, 3-6 December 1986 P25-52. Publ Rotterdam: A A Balkema, 1989 The application of a 3D probabilistic computer code (PROBISH), based on the variance reduction technique,'-I0 the stability of an embankment and comparison of output to that of prior Monte Carlo analysis are presented. The only random variable considered was the undrained shear strength from field vane tests. Total stress analysis and Bishop's simplified method of slices were used. For a design criteria probability of failure of 0.001, safety factors of 1.12 and 1.28 respectively were recommended for 3D and 2D analysis. Probability of failure predicted is lower than that from Monte Carlo analysis.

© 1991 Pergamon Press pie. Reproduction not permitted