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Elastoplastic analysis of soil-pile interaction
380A 926314 Effects of undermining a gravel road near Secunda by Iongwalling Netterberg, F; van der Merwe, J N
Proc Tenth Regional Conference for Africa on Soil Mechanics and Foundation Engineering and the Third International Conference on Tropical and Residual Soils, Maseru, 23-27 September 1991 V1, P205-212. Publ Rotterdam: A A Balkema, 1991 The response of an untrafficked gravel bypass to longwall coal mining some 120m below is described. Visual inspections, measurements of coordinates and levels, measurements of ride quality, and strength tests (dynamic CPT) were carried out. Maximum vertical subsidence of 1.3m, tension cracks up to 40mm wide, and one compression ridge were found. Ride quality fell, but it is considered that a speed of 60kph would still be permissable. The road could probably have been kept open without maintenance.
Foundations See also: 926053, 926218, 926301, 926304, 926306, 926307 926315 Axial load transfer for piles in sand. I. Tests on an instrumented precast pile Altaee, A; Fellenius, B H; Evgin, E Can Geotech d V29, N1, Feb 1992, Pll-20 A 12m long square concrete pile was driven into a sand deposit and subject to 3 compression and 1 tension static load tests. Load distributions on the pile were measured during the tests. Observed load distributions indicated a critical depth, but this disappeared when residual load before testing was taken into account. Analysis indicates that load distribution is a function of effective overburden stresses in the soil over the entire pile length. Shaft resistance degraded slightly from test to test, but was about the same in compression and tension. Parameters controlling pile capacity were evaluated to allow extrapolation of results to other piles at the site. 926316 Axial load transfer for piles in sand. II. Numerical analysis Altaee, A; Evgin, E; Fellenius, B H Can Geotech J 1/29, NI, Feb 1992, P21-30 Nonlinear finite element analysis was used to model pile tests in sand, described in a companion paper. A bounding surface plasticity model was used to describe the response of the sand to repeated loading. Good agreement is found between calculated and observed load-pile head movement relations, load transfer, and shaft resistance in compression and tension loading. Observed degradation of shaft resistance and increase of toe resistance with repeated loading were reproduced. The finite element analysis confirms the field evidence that the critical-depth concept is invalid in this case. 926317 Elastoplastic analysis of soil-pile interaction Cheung, Y K; Lee, P K K; Zhao, W B Comput Geotech VI2, N2, 1991, Pl15-132 Finite element analysis of soil-pile interaction is presented. The analysis uses Goodman interface elements and LinearElastic, Duncan-Chang,Yin, and modified Cam-Clay constitutive models. Calculated responses are compared to observed behaviour of a pile in silty clay over silty sand. It is demonstrated that for reasonable simulation of field behaviour it is necessary to consider elastoplastic behaviour of the soil and effects of overconsolidation.
926318 Some numerical experiments with a three dimensional finite element model of a laterally loaded pile. Technical note Brown, D A; Shie, C F Comput Geotech V12, N2, 1991, P149-162 A finite element model developed by the authors and including a plasticity soil model and interface elements which allow gap formation is used to investigate the effects of various parameters on calculated p-y curves. Influences of pilehead fixicity, in situ soil stresses, interface friction, and sloping ground are examined. Results are discussed considering relevance to typical p-y curves used for pile design in clay soils.
926319 Pile-soil-pile interaction considering weakened zone of soil around piles. Technical note Chow, Y K Comput Geotech VI2, N2, 1991, P163-174 Even under working conditions, loading of piles results in high shear strains in the immediate vicinity of the pile shaft. This gives rise to a weakened zone around each pile. Finite element analysis of pile group settlement is presented in which the weakened zone is included. Predictions are compared to field data from jacked and driven piles in clay. Inclusion of the weakened zone allows improved simulation of the observed behaviour.
926320 Unpaved geosynthetic-built resource access roads: stiffness rather than rut depth as the key design criterion Douglas, R A; Valsangkar, A J Geotext Geomem VII, NI, 1992, P45-59 Transport costs are linked to the relations between vehiclcs and roads. Road stiffness influences fuel consumption and it is proposed that road stiffness rather than permanent rut depth is the key design criterion. The latter parameter as used to design sealed roads is not applicable to unsealed access roads where ruts can be easily removed in routine maintenance. Inclusion of geogrids or geotextiles will improve stiffness of low quality access roads. Cyclic loading tests on large scale model pavement sections of reinforced granular bases over peat subgrades have been used to evaluate expected improvement.
926321 Further contributions to reliability-based pile-settlement analysis Quek, S T; Chow, Y K; Phoon, K K J Geotech Engng Div A S C E VII& N5. May 1992, P726-742 Probabilistic analysis of pile settlements requires uncertainty in Young's modulus to be estimated. Estimation statistics of Young's modulus are examined, considering model uncertainty and uncertainty due to inherent soil variability. The soil is considered as a spatially random variable in the evaluation of model uncertainty. Numerical analysis is used to show how the two uncertainties can be treated simultaneously in evaluation of the reliability of the foundation against an allowable settlement limit using design charts. The validity of these charts, obtained from first order analysis, is confirmed by presenting the results of second order analysis.
~:) 1992 Pergamon Press Ltd. Reproduction not permitted
Proc Tenth Regional Conference for Africa on Soil Mechanics and Foundation Engineering and the Third International Conference on Tropical and Residual Soils, Maseru, 23-27 September 1991 V1, P205-212. Publ Rotterdam: A A Balkema, 1991 The response of an untrafficked gravel bypass to longwall coal mining some 120m below is described. Visual inspections, measurements of coordinates and levels, measurements of ride quality, and strength tests (dynamic CPT) were carried out. Maximum vertical subsidence of 1.3m, tension cracks up to 40mm wide, and one compression ridge were found. Ride quality fell, but it is considered that a speed of 60kph would still be permissable. The road could probably have been kept open without maintenance.
Foundations See also: 926053, 926218, 926301, 926304, 926306, 926307 926315 Axial load transfer for piles in sand. I. Tests on an instrumented precast pile Altaee, A; Fellenius, B H; Evgin, E Can Geotech d V29, N1, Feb 1992, Pll-20 A 12m long square concrete pile was driven into a sand deposit and subject to 3 compression and 1 tension static load tests. Load distributions on the pile were measured during the tests. Observed load distributions indicated a critical depth, but this disappeared when residual load before testing was taken into account. Analysis indicates that load distribution is a function of effective overburden stresses in the soil over the entire pile length. Shaft resistance degraded slightly from test to test, but was about the same in compression and tension. Parameters controlling pile capacity were evaluated to allow extrapolation of results to other piles at the site. 926316 Axial load transfer for piles in sand. II. Numerical analysis Altaee, A; Evgin, E; Fellenius, B H Can Geotech J 1/29, NI, Feb 1992, P21-30 Nonlinear finite element analysis was used to model pile tests in sand, described in a companion paper. A bounding surface plasticity model was used to describe the response of the sand to repeated loading. Good agreement is found between calculated and observed load-pile head movement relations, load transfer, and shaft resistance in compression and tension loading. Observed degradation of shaft resistance and increase of toe resistance with repeated loading were reproduced. The finite element analysis confirms the field evidence that the critical-depth concept is invalid in this case. 926317 Elastoplastic analysis of soil-pile interaction Cheung, Y K; Lee, P K K; Zhao, W B Comput Geotech VI2, N2, 1991, Pl15-132 Finite element analysis of soil-pile interaction is presented. The analysis uses Goodman interface elements and LinearElastic, Duncan-Chang,Yin, and modified Cam-Clay constitutive models. Calculated responses are compared to observed behaviour of a pile in silty clay over silty sand. It is demonstrated that for reasonable simulation of field behaviour it is necessary to consider elastoplastic behaviour of the soil and effects of overconsolidation.
926318 Some numerical experiments with a three dimensional finite element model of a laterally loaded pile. Technical note Brown, D A; Shie, C F Comput Geotech V12, N2, 1991, P149-162 A finite element model developed by the authors and including a plasticity soil model and interface elements which allow gap formation is used to investigate the effects of various parameters on calculated p-y curves. Influences of pilehead fixicity, in situ soil stresses, interface friction, and sloping ground are examined. Results are discussed considering relevance to typical p-y curves used for pile design in clay soils.
926319 Pile-soil-pile interaction considering weakened zone of soil around piles. Technical note Chow, Y K Comput Geotech VI2, N2, 1991, P163-174 Even under working conditions, loading of piles results in high shear strains in the immediate vicinity of the pile shaft. This gives rise to a weakened zone around each pile. Finite element analysis of pile group settlement is presented in which the weakened zone is included. Predictions are compared to field data from jacked and driven piles in clay. Inclusion of the weakened zone allows improved simulation of the observed behaviour.
926320 Unpaved geosynthetic-built resource access roads: stiffness rather than rut depth as the key design criterion Douglas, R A; Valsangkar, A J Geotext Geomem VII, NI, 1992, P45-59 Transport costs are linked to the relations between vehiclcs and roads. Road stiffness influences fuel consumption and it is proposed that road stiffness rather than permanent rut depth is the key design criterion. The latter parameter as used to design sealed roads is not applicable to unsealed access roads where ruts can be easily removed in routine maintenance. Inclusion of geogrids or geotextiles will improve stiffness of low quality access roads. Cyclic loading tests on large scale model pavement sections of reinforced granular bases over peat subgrades have been used to evaluate expected improvement.
926321 Further contributions to reliability-based pile-settlement analysis Quek, S T; Chow, Y K; Phoon, K K J Geotech Engng Div A S C E VII& N5. May 1992, P726-742 Probabilistic analysis of pile settlements requires uncertainty in Young's modulus to be estimated. Estimation statistics of Young's modulus are examined, considering model uncertainty and uncertainty due to inherent soil variability. The soil is considered as a spatially random variable in the evaluation of model uncertainty. Numerical analysis is used to show how the two uncertainties can be treated simultaneously in evaluation of the reliability of the foundation against an allowable settlement limit using design charts. The validity of these charts, obtained from first order analysis, is confirmed by presenting the results of second order analysis.
~:) 1992 Pergamon Press Ltd. Reproduction not permitted