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Dam design - for African environments
SURFACE STRUCTURES:DAMS & EMBANKMENTS
248A
945193 Pullout behaviour of model pile and helical pile anchors subjected to lateral cyclic loading Y. V. S. N. Prasad & S. N. Rao, Canadian Geotechnical Journal, 31(1), 1994, pp 110-119. This paper presents the effect of lateral cyclic loading on the pullout capacity of model and helical piles in clayey soil. Reduction in pullout capacity mainly depends upon the lateral deflection of the pile during cyclic loading and the embedment ratio of the pile. This reduction in the pullout capacity of model piles is presented in terms of nondimensional parameters. However, in the case of helical piles under similar conditions, it was found that the lateral cyclic loading has very little influence on the pullout capacity. The reasons for the better performance of helical piles over ordinary piles are explained. -from Authors
945194 Behavior of soil plugs in open-ended model piles driven into sands Kyu-Ho Paik & Seung-Rae Lee, Marine Georesources & Geotechnology, 11(4), 1993, pp 353-373. Calibration chamber tests were conducted on open-ended model piles driven into dried siliceous sands with different soil conditions in order to clarify the effect of soil conditions on load transfer mechanism in the soil plug. Under several assumptions, the value of earth pressure coefficient in the soil plug can be calculated. It gradually reduces with increase in the longitudinal distances from the pile tip. At the bottom of the soil plug, it tends to decrease with increase in the penetration depth and relative density, and to increase with the increase of ambient pressure. Based on the test results, an empirical equation was suggested to compute the earth pressure coefficient to be used in the calculation of plug capacity using one-dimensional analysis, and it produces proper plug capacities for all soil conditions. -from Authors
945195 Previsao da capacidade de carga de estacas em argilas atraves do ensaio piezocone (Prediction of axial pile capacity in clays using piezocone tests) M. De S. Soares De Almeida & T. Lurme, Solos e Rochas, 16(4), 1993, pp 217-227. A data base has been established with loads measured on instrumented model piles and results from piezocone tests in clay deposits. A new method is proposed where pile skin friction and point resistance are computed via the net point resistance q = a_ - ~ The new method has the potenttal of being a use~dl supplement to exlstmg methods for computing the axial capaclty of piles in clays. -English summary •
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945198 A retroanalise de sinais de cravacao de estacas: observacoes registradas e sua interpretacao (Backanalysis of pile driving records: some observations and their interpretation) B. Ragoni Danziger, A. Maia Da Costa, F. De Rezende Lopes & M. Peigas Pacheco, Solos e Rochas, 16(4), 11993, pp 313-323. The back-analysis of driving records consists in a CAPWAP-type analysis carried out with records of forces and velocities measured at the pile head, aiming at the determination of side shear distribution, point resistance and other soil parameters. In the DINEXP-1D Program (Costa, 1988), the force record is input and the analysis produces a velocity prediction to be compared with the velocity record. The back-analysis is an interativeprocess which leads to a match between theprodieted a n d measured velocities when the adequate values of soil parameters are input. -from English summary 945199 An approximate numerical analysis of pileraft interaction H. G. Poulos, International Journal for Numerical & Analytical Methods in Geomechanics, 18(2), 1994, pp 73-92. Presents an approximate method of numerical analysis of pile-raft foundations in which the raft is modelled as a thin plate and the piles as interacting springs of appropriate stiffness. Comparisons between this analysis and extsting solutions verify that, despite the approximations involved, the analysis can provide solutions o f adequate accuracy for the settlement and pile load distribution within a piled raft. Comparisons are also made with the results of a series of centrifuge tests and with measurements of the performance of a full-scale piled raft. In both cases, the analysis predicts very well the settlement and proportion of load carried by the piles. -from Author 945200 Development of a method of compacting saturated sand soils by blasts u n d e r winter conditions O. P. Minaev & A. P. Krutov, Hydrotechnical Construction, 27(7), 1994,,pp 424-428; translated from: Gidrotekhnicheskoe Stroitel stvo, 7, 1993, pp 43-46. Describes the development and use of a method of compacting soils by deep detonation of explosive charges. This technique has been used to compact saturated sand soils for foundations of the St. Petersburg flood control barrier. -J.M.McLaughlin
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945196 Metodo de dimensionamento de iastros de brita sobre estacas com capiteis (A design method for g r a n u l a r bases over piles with caps) M. Ehrlich, Solos e Rochas, 16(4), 1993, pp 229-234. Granular bases over piles with caps have been an alternative - with technical and economic advantage - for the foundation of tanks and embankments on soft clay. This alternative allows an increase in bearing capacity and a reduction in foundation settlements. The currently used design methods are largely based on simplified hypothesis. Some of these currently used methods are discussed and a new analytical method is presented in this paper. -English summary 945197 Estacas granulares em solos moles: uma verificacao in situ (Granular piles in soft soils: an in situ application) E. Minette, D. Cardoso De Lima, P. S. De Alrneida Barbosa & C. H. De Carvalho Silva, Solos e Rochas, 17(1), 1994, pp 57-63. This paper describes the main applications and a methdology ~or installing granular piles in soft soils. The main design parameters for this soil reinforcement is present. Results of a load test performed on a single pile are presented. -English summary
Dams and embankments 945201 Dam design - for African environments A. D. W. Sparks, in: Geotechnics in the African Environment. Vol. 2, ed G.E. Blight & others, (Balkema), 1994, pp 555-562. The paper provides a general slope stability method for a general shape of slip surface, and also design guide lines for dams in semi-arid climates. Probabilistic methods based on variations of shear strength are combined with probabilities based on the time return periods for floods and earthquakes. -Author 945202 Lateral response of dams in semi-elliptical rigid canyons P. Dakoulas & C. Hsu, Soil Dynamics & Earthquake Engineering, 12(8), 1993, pp 497-507. An analytical closed-form solution is developed for the lateral response of earth and rockfiU dams built in semielliptical canyons. Results are presented for natural frequencies, modal displacement shapes, participation factors, and response to transient and steady-state harmonic base excitation for various dam length-to-height ratios. Comparisons are made of the effects of the length-to-height ratio and the canyon shape on the response of darns b u t t in sem~-emptical and rectangular canyons. A subsequent study extends this model to a semi-elliptical canyonl~ consisting of flexible elastic rock, subjected to obliquely incident harmonic SH waves. -from Authors
248A
945193 Pullout behaviour of model pile and helical pile anchors subjected to lateral cyclic loading Y. V. S. N. Prasad & S. N. Rao, Canadian Geotechnical Journal, 31(1), 1994, pp 110-119. This paper presents the effect of lateral cyclic loading on the pullout capacity of model and helical piles in clayey soil. Reduction in pullout capacity mainly depends upon the lateral deflection of the pile during cyclic loading and the embedment ratio of the pile. This reduction in the pullout capacity of model piles is presented in terms of nondimensional parameters. However, in the case of helical piles under similar conditions, it was found that the lateral cyclic loading has very little influence on the pullout capacity. The reasons for the better performance of helical piles over ordinary piles are explained. -from Authors
945194 Behavior of soil plugs in open-ended model piles driven into sands Kyu-Ho Paik & Seung-Rae Lee, Marine Georesources & Geotechnology, 11(4), 1993, pp 353-373. Calibration chamber tests were conducted on open-ended model piles driven into dried siliceous sands with different soil conditions in order to clarify the effect of soil conditions on load transfer mechanism in the soil plug. Under several assumptions, the value of earth pressure coefficient in the soil plug can be calculated. It gradually reduces with increase in the longitudinal distances from the pile tip. At the bottom of the soil plug, it tends to decrease with increase in the penetration depth and relative density, and to increase with the increase of ambient pressure. Based on the test results, an empirical equation was suggested to compute the earth pressure coefficient to be used in the calculation of plug capacity using one-dimensional analysis, and it produces proper plug capacities for all soil conditions. -from Authors
945195 Previsao da capacidade de carga de estacas em argilas atraves do ensaio piezocone (Prediction of axial pile capacity in clays using piezocone tests) M. De S. Soares De Almeida & T. Lurme, Solos e Rochas, 16(4), 1993, pp 217-227. A data base has been established with loads measured on instrumented model piles and results from piezocone tests in clay deposits. A new method is proposed where pile skin friction and point resistance are computed via the net point resistance q = a_ - ~ The new method has the potenttal of being a use~dl supplement to exlstmg methods for computing the axial capaclty of piles in clays. -English summary •
.
net
•
vo"
.
945198 A retroanalise de sinais de cravacao de estacas: observacoes registradas e sua interpretacao (Backanalysis of pile driving records: some observations and their interpretation) B. Ragoni Danziger, A. Maia Da Costa, F. De Rezende Lopes & M. Peigas Pacheco, Solos e Rochas, 16(4), 11993, pp 313-323. The back-analysis of driving records consists in a CAPWAP-type analysis carried out with records of forces and velocities measured at the pile head, aiming at the determination of side shear distribution, point resistance and other soil parameters. In the DINEXP-1D Program (Costa, 1988), the force record is input and the analysis produces a velocity prediction to be compared with the velocity record. The back-analysis is an interativeprocess which leads to a match between theprodieted a n d measured velocities when the adequate values of soil parameters are input. -from English summary 945199 An approximate numerical analysis of pileraft interaction H. G. Poulos, International Journal for Numerical & Analytical Methods in Geomechanics, 18(2), 1994, pp 73-92. Presents an approximate method of numerical analysis of pile-raft foundations in which the raft is modelled as a thin plate and the piles as interacting springs of appropriate stiffness. Comparisons between this analysis and extsting solutions verify that, despite the approximations involved, the analysis can provide solutions o f adequate accuracy for the settlement and pile load distribution within a piled raft. Comparisons are also made with the results of a series of centrifuge tests and with measurements of the performance of a full-scale piled raft. In both cases, the analysis predicts very well the settlement and proportion of load carried by the piles. -from Author 945200 Development of a method of compacting saturated sand soils by blasts u n d e r winter conditions O. P. Minaev & A. P. Krutov, Hydrotechnical Construction, 27(7), 1994,,pp 424-428; translated from: Gidrotekhnicheskoe Stroitel stvo, 7, 1993, pp 43-46. Describes the development and use of a method of compacting soils by deep detonation of explosive charges. This technique has been used to compact saturated sand soils for foundations of the St. Petersburg flood control barrier. -J.M.McLaughlin
.
945196 Metodo de dimensionamento de iastros de brita sobre estacas com capiteis (A design method for g r a n u l a r bases over piles with caps) M. Ehrlich, Solos e Rochas, 16(4), 1993, pp 229-234. Granular bases over piles with caps have been an alternative - with technical and economic advantage - for the foundation of tanks and embankments on soft clay. This alternative allows an increase in bearing capacity and a reduction in foundation settlements. The currently used design methods are largely based on simplified hypothesis. Some of these currently used methods are discussed and a new analytical method is presented in this paper. -English summary 945197 Estacas granulares em solos moles: uma verificacao in situ (Granular piles in soft soils: an in situ application) E. Minette, D. Cardoso De Lima, P. S. De Alrneida Barbosa & C. H. De Carvalho Silva, Solos e Rochas, 17(1), 1994, pp 57-63. This paper describes the main applications and a methdology ~or installing granular piles in soft soils. The main design parameters for this soil reinforcement is present. Results of a load test performed on a single pile are presented. -English summary
Dams and embankments 945201 Dam design - for African environments A. D. W. Sparks, in: Geotechnics in the African Environment. Vol. 2, ed G.E. Blight & others, (Balkema), 1994, pp 555-562. The paper provides a general slope stability method for a general shape of slip surface, and also design guide lines for dams in semi-arid climates. Probabilistic methods based on variations of shear strength are combined with probabilities based on the time return periods for floods and earthquakes. -Author 945202 Lateral response of dams in semi-elliptical rigid canyons P. Dakoulas & C. Hsu, Soil Dynamics & Earthquake Engineering, 12(8), 1993, pp 497-507. An analytical closed-form solution is developed for the lateral response of earth and rockfiU dams built in semielliptical canyons. Results are presented for natural frequencies, modal displacement shapes, participation factors, and response to transient and steady-state harmonic base excitation for various dam length-to-height ratios. Comparisons are made of the effects of the length-to-height ratio and the canyon shape on the response of darns b u t t in sem~-emptical and rectangular canyons. A subsequent study extends this model to a semi-elliptical canyonl~ consisting of flexible elastic rock, subjected to obliquely incident harmonic SH waves. -from Authors