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Bearing capacity of bored short piles
370A 906383 Shaft friction of bored piles in terms of effective strength Burland, J B; Twine, D Proc 1st International Geotechnical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P411-420. Publ Rotterdam: A A Balkema, 1988 Results of many tests on bored cast-in-situ piles in overconsolidated clays are re-analysed assuming excess pore pressure is completely dissipated, fully drained conditions, and zero effective cohesion at pile-soil interface. Results indicate that shaft friction from maintained loading tests corresponds to values of angles of friction close to the residual value. This leads to a reasonable design method which provides a lower bound to the test data. Constant rate of penetration tests overestimate static shaft friction due to rate effects, and slow rates of penetration are recommended. 906384 Skin bearing capacity of piles Imre, E Proc 1st International Geoteclmical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P421-428. Publ Rotterdam: A A Balkema, 1988 Photographic evidence indicates that the stress field around a deep foundation within about 1/4 of a pile diameter from the pile wall resembles that in a silo - soil arching occurs. A new theoretical assessment of pile friction is made, taking into account arching above a local softening of an annulus around the pile. A hypothesis to interpret yield and peak points in total side resistance versus settlement curves is presented. A heuristic method for calculation of shaft yield resistance in layered soils is presented, based on conventional loading tests and penetration test data. Examples of its application are illustrated.
906387 Load bearing capacity of bored piles, a problem not yet satisfactorily solved - some suggestions Lizzi, F Proc 1st International Geotechnicai Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P443-450. Publ Rotterdam: ,4 A Balkema, 1988 Full scale load testing of bored piles for design verification is very expensive. Instrumental data for prediction of bearing capacity must be viewed with some suspicion as the instruments are completely different in structure to the pile. The use of a 'pilot pile' to assess bearing capacity and soil structure interaction is proposed. This uses a smaller diameter pile of the same type and length as the prototype, constructed in the same soil with the same technology. Problems of size effect and the relative contributions of side and base resistance are discussed. 906388 Ultimate bored pile load capacity in granular soils: a case history against the current effective stress design theory in comparison to a penetration based design method Mordhorst, C Proc 1st International Geoteclmical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P431-456. Publ Rotterdam: A A Balkema, 1988 Bearing capacity of bored piles in granular soils is often calculated using adaptations of the theoretical formulae for base bearing capacity and Mohr-Coulomb shear theory for shaft friction. These equations are known to give unsatisfactory results. Assumptions and modifications of the classical theories are reviewed. A comparison is made on the basis of case history data between predictions of modified theory and the design code DIN 4014, based on CPT data.
906385 Loading tests on bored piles, inserted nodular and cylindrical piles Kanai, S; Yabuuchi, S Proc 1st International Geoteclmical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P429-434. Publ Rotterdam: A A Balkema, 1988
906389 Bearing capacity of bored short piles Pula, O; Rybak, C Proc 1st International Geoteelmieal Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P467-470. Publ Rotterdam: A A Balkema, 1988
Comparison is made between bearing capacities of bored and driven smooth cylindrical piles and cylindrical piles with annular nodules at lm intervals, set by the auger drill/cement milk method. Horizontal and vertical loading tests were carfled out at two sites, one layered sand/silt, the other layered sand/clay/gravel. The nodular piles had higher bearing capacity because of increased skin friction. In horizontal loading, horizontal resistances were almost equal, despite the much greater bending stiffness of the nodular pile.
Short piles, less than 5m in length, have been used where there is a bearing layer 2-3m below non-bearing subsoil and water table is high. Predicted capacities according to the theory of Grigorian (1970) and Pula (1975) are compared to field test results for cohesive and cohesionless soils. Capacities are much less than for piles of 'normal' length, but short piles can provide a useful alternative to shallow foundations under suitable soil conditions. Significant bearing capacity increases are possible if expanded bases can be formed.
906386 Development of shin friction and base resistance of instrumented large bored piles under working load conditions Kruizinga, J Proc 1st International Geoteelmieal Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P435-442. Publ Rotterdam: A A Balkema, 1988
906390 Comparison of predicted and measured bearing capacity of anger piles Rizkallah, V Proe 1st International Geoteclmical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P471-475. Publ Rotterdam: A A Balkema, 1988
During construction of a viaduct in sandy soils, two large bored piles were instrumented to obtain data to check design rules used to predict load settlement behaviour. Recorded strains were translated into normal forces, with variation of elastic properties of the concrete taken into account. Development of pile friction and base resistance were studied as a function of both working load and pile head deformation.
Prediction of ultimate bearing capacity on the basis of CPT results according to DIN 4014 is discussed for full displacement and partial displacement auger piles. Key parameters are assessment of undrained shear strength and interpretation of CPT results in different soils. Predicted load-settlement behaviour is compared to results of pile load tests, and the predictions are seen to be unacceptably low.
© 1990 Pergamon Press pie. Reproduction not permitted
906387 Load bearing capacity of bored piles, a problem not yet satisfactorily solved - some suggestions Lizzi, F Proc 1st International Geotechnicai Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P443-450. Publ Rotterdam: ,4 A Balkema, 1988 Full scale load testing of bored piles for design verification is very expensive. Instrumental data for prediction of bearing capacity must be viewed with some suspicion as the instruments are completely different in structure to the pile. The use of a 'pilot pile' to assess bearing capacity and soil structure interaction is proposed. This uses a smaller diameter pile of the same type and length as the prototype, constructed in the same soil with the same technology. Problems of size effect and the relative contributions of side and base resistance are discussed. 906388 Ultimate bored pile load capacity in granular soils: a case history against the current effective stress design theory in comparison to a penetration based design method Mordhorst, C Proc 1st International Geoteclmical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P431-456. Publ Rotterdam: A A Balkema, 1988 Bearing capacity of bored piles in granular soils is often calculated using adaptations of the theoretical formulae for base bearing capacity and Mohr-Coulomb shear theory for shaft friction. These equations are known to give unsatisfactory results. Assumptions and modifications of the classical theories are reviewed. A comparison is made on the basis of case history data between predictions of modified theory and the design code DIN 4014, based on CPT data.
906385 Loading tests on bored piles, inserted nodular and cylindrical piles Kanai, S; Yabuuchi, S Proc 1st International Geoteclmical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P429-434. Publ Rotterdam: A A Balkema, 1988
906389 Bearing capacity of bored short piles Pula, O; Rybak, C Proc 1st International Geoteelmieal Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P467-470. Publ Rotterdam: A A Balkema, 1988
Comparison is made between bearing capacities of bored and driven smooth cylindrical piles and cylindrical piles with annular nodules at lm intervals, set by the auger drill/cement milk method. Horizontal and vertical loading tests were carfled out at two sites, one layered sand/silt, the other layered sand/clay/gravel. The nodular piles had higher bearing capacity because of increased skin friction. In horizontal loading, horizontal resistances were almost equal, despite the much greater bending stiffness of the nodular pile.
Short piles, less than 5m in length, have been used where there is a bearing layer 2-3m below non-bearing subsoil and water table is high. Predicted capacities according to the theory of Grigorian (1970) and Pula (1975) are compared to field test results for cohesive and cohesionless soils. Capacities are much less than for piles of 'normal' length, but short piles can provide a useful alternative to shallow foundations under suitable soil conditions. Significant bearing capacity increases are possible if expanded bases can be formed.
906386 Development of shin friction and base resistance of instrumented large bored piles under working load conditions Kruizinga, J Proc 1st International Geoteelmieal Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P435-442. Publ Rotterdam: A A Balkema, 1988
906390 Comparison of predicted and measured bearing capacity of anger piles Rizkallah, V Proe 1st International Geoteclmical Seminar on Deep Foundations on Bored and Auger Piles, Ghent, 7-10 June 1988 P471-475. Publ Rotterdam: A A Balkema, 1988
During construction of a viaduct in sandy soils, two large bored piles were instrumented to obtain data to check design rules used to predict load settlement behaviour. Recorded strains were translated into normal forces, with variation of elastic properties of the concrete taken into account. Development of pile friction and base resistance were studied as a function of both working load and pile head deformation.
Prediction of ultimate bearing capacity on the basis of CPT results according to DIN 4014 is discussed for full displacement and partial displacement auger piles. Key parameters are assessment of undrained shear strength and interpretation of CPT results in different soils. Predicted load-settlement behaviour is compared to results of pile load tests, and the predictions are seen to be unacceptably low.
© 1990 Pergamon Press pie. Reproduction not permitted