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Large diameter bored piles
200A
865236 Extension of the Pasternak Foundation concept Poorooshasb, H B: Pietruszczak, S: Ashtakala. B Soils Found V25, N3. Sept 1985, P31-40 The Pasternak Foundation concept, a refinement of the Winkler Foundation theory, is briefly stated and its shortcomings pointed out. The concept is extended to take into account material nonlinearity and body forces using an analytical approach. In conclusion, an examination of the proposals of Meyerhof and Hanna regarding the behaviour of two layer soil systems is presented. Auth.
865237 Uplift behaviour of short piles in uniform sand Subba Rao, K S: Venkatesh, K H Soils Found V25, N4. Dec 1985. PI-7 Uplift behaviour was examined for smooth and rough mild steel model piles in two uniform sands, in dry and submerged conditions and at two densities. Uplift capacity increased with pile L/D ratio, roughness, soil density and particle size. Pile movements of 5 and 10% diameter in loose and dense sands respectively were needed to mobilise uplift capacity. These values are greater than those required for shaft loads in push-in tests. Skin friction is much lower in uplift than in push-in testing, especially t\~r rough piles. Submergence reduced uplift capacity in all cases, but earth pressure coefficients reduced only for piles in dense sand and were almost unaffected for piles in loose sands.
865238 Bending of a hatter pile due to ground settlement Takahashi, K Soils Found V25. N4. Dee 1985. P75-91 A method of computer analysis of the flcxural bchaviour of a batter pile duc to ground settlement is presented. The pile is divided into four sections according to ground conditions, and a Winklcr subgrade is assumed for the subsiding clay ground. Both laboratory and field tests were carried out to prove the model. In the laboratory, the effect of angle of inclination was studied, and in the field the effect of asphalt coating on reducing negative skin friction was examined. Strains in the pile shaft, bending moments and ground settlement were monitored with time. Comparison of test results with predictions from the suggested method, Sato's method and finite element analysis shows that all give good approximations of observed behaviour, but best agreement is with the suggested method.
865239 Non-linear analysis of pile structures Yokoyama, Y Soils Found V25, N4. Dec 1985. P92-102 A simple and practical design method, based on the modulus of subgrade reaction method, is presented, which can take into account nonlinear behaviour of soil-pile structures, yet can be implemented on a microcomputer. Loading test data are used to validate the proposed method.
865240 Uplift capacity of rigid steel pile groups in clay. Technical note Das, B M; Azim, M F Soils Found V25, N4. Dec" 1985, PII7-I22 Laboratory model test results for the ultimate uplift capacity of group piles embedded in clay have been presented. The length-to-diameter ratios of the group piles tested under this
program have been kept at 12 and 15. The group uplift efficiency varies with the embedment ratio, number of piles in the group, and the centre to centre spacing of the piles. For the present tests, a group efficiency of about 100% is reached at a centre to centre spacing of 6 to 7 pile diameters. Auth.
865241 Long term behaviour of a drilled shaft in expansive soil Johnson, L D; Stroman. W R Trans Res Rec N1032. 1985. P53-59 Vertical load tests were carried out on an instrumented. 36ft long drilled pile in expansive clay soil. Soil heave adjacent to the pile was significantly greater than heave of the pile itself. Soil heave near the base of the pile was relatively small, indicating that the pile had stretched or fractured along its length. Load tests indicated a reduced end bearing capacity, which is attributed to shaft heave, which lifted the base off the soil, contributing to a possible void, and soil heave with softening beneath the base and shaft fracture near the base. Design implications for pile foundations in swelling soils are examined.
865242 Large diameter bored piles Engelhardt, K Proc Symposium on Recent Developments in Ground Improvement Techniques, Bangkok, 29 Nov-3 Dec 1982 PI31142. Puhl Rotter~htm: A. A. Balkema. 1985 The construction of large diameter bored piles in different soils, using special drilling methods, is described. Results o1" load tests, using different test equipment, are given. Three examples are described showing how large diameter bored piles were employed for the foundations of large bridges.
865243 ,Mathematical model for vibratory pile driving Dicker, D Proc 5th Engineering Mechan&s Division Speciality Conference, Wyoming, !-3 Aug 1984 VI. P305-307. Puhl New York. ASCE, 1984 The interaction between a vertical end bearing pile and a linearly elastic foundation medium is analysed. This is one of a series of mathematical models being studied in order to develop methods of predicting the load capacity from the vibrating driving record.
865244 Dynamic effective stress response of soil structures: theory and centrifuge model studies Finn, W D L Proe 5th International Conference on Numerical Ah'thods in Geomechanics, Nagoya, I-5 April 1985 Vl. P35-46. Puhl Rotterdam: A. A. Balkema, 1985 A method for non-linear dynamic effective stress analysis is introduced which is applicable to the soil structure interaction problems. Its scope is demonstrated by analysis of a drilling island consisting of a ballasted tank placed on a submerged sand berm. Full interaction, including potential slip between tank and berm, is taken into account. Verification is provided by data from simulated earthquake tests on a centrifuged model. Auth.
~ 1986 Pergamon Journals Ltd. Reproduction not permitted
865236 Extension of the Pasternak Foundation concept Poorooshasb, H B: Pietruszczak, S: Ashtakala. B Soils Found V25, N3. Sept 1985, P31-40 The Pasternak Foundation concept, a refinement of the Winkler Foundation theory, is briefly stated and its shortcomings pointed out. The concept is extended to take into account material nonlinearity and body forces using an analytical approach. In conclusion, an examination of the proposals of Meyerhof and Hanna regarding the behaviour of two layer soil systems is presented. Auth.
865237 Uplift behaviour of short piles in uniform sand Subba Rao, K S: Venkatesh, K H Soils Found V25, N4. Dec 1985. PI-7 Uplift behaviour was examined for smooth and rough mild steel model piles in two uniform sands, in dry and submerged conditions and at two densities. Uplift capacity increased with pile L/D ratio, roughness, soil density and particle size. Pile movements of 5 and 10% diameter in loose and dense sands respectively were needed to mobilise uplift capacity. These values are greater than those required for shaft loads in push-in tests. Skin friction is much lower in uplift than in push-in testing, especially t\~r rough piles. Submergence reduced uplift capacity in all cases, but earth pressure coefficients reduced only for piles in dense sand and were almost unaffected for piles in loose sands.
865238 Bending of a hatter pile due to ground settlement Takahashi, K Soils Found V25. N4. Dee 1985. P75-91 A method of computer analysis of the flcxural bchaviour of a batter pile duc to ground settlement is presented. The pile is divided into four sections according to ground conditions, and a Winklcr subgrade is assumed for the subsiding clay ground. Both laboratory and field tests were carried out to prove the model. In the laboratory, the effect of angle of inclination was studied, and in the field the effect of asphalt coating on reducing negative skin friction was examined. Strains in the pile shaft, bending moments and ground settlement were monitored with time. Comparison of test results with predictions from the suggested method, Sato's method and finite element analysis shows that all give good approximations of observed behaviour, but best agreement is with the suggested method.
865239 Non-linear analysis of pile structures Yokoyama, Y Soils Found V25, N4. Dec 1985. P92-102 A simple and practical design method, based on the modulus of subgrade reaction method, is presented, which can take into account nonlinear behaviour of soil-pile structures, yet can be implemented on a microcomputer. Loading test data are used to validate the proposed method.
865240 Uplift capacity of rigid steel pile groups in clay. Technical note Das, B M; Azim, M F Soils Found V25, N4. Dec" 1985, PII7-I22 Laboratory model test results for the ultimate uplift capacity of group piles embedded in clay have been presented. The length-to-diameter ratios of the group piles tested under this
program have been kept at 12 and 15. The group uplift efficiency varies with the embedment ratio, number of piles in the group, and the centre to centre spacing of the piles. For the present tests, a group efficiency of about 100% is reached at a centre to centre spacing of 6 to 7 pile diameters. Auth.
865241 Long term behaviour of a drilled shaft in expansive soil Johnson, L D; Stroman. W R Trans Res Rec N1032. 1985. P53-59 Vertical load tests were carried out on an instrumented. 36ft long drilled pile in expansive clay soil. Soil heave adjacent to the pile was significantly greater than heave of the pile itself. Soil heave near the base of the pile was relatively small, indicating that the pile had stretched or fractured along its length. Load tests indicated a reduced end bearing capacity, which is attributed to shaft heave, which lifted the base off the soil, contributing to a possible void, and soil heave with softening beneath the base and shaft fracture near the base. Design implications for pile foundations in swelling soils are examined.
865242 Large diameter bored piles Engelhardt, K Proc Symposium on Recent Developments in Ground Improvement Techniques, Bangkok, 29 Nov-3 Dec 1982 PI31142. Puhl Rotter~htm: A. A. Balkema. 1985 The construction of large diameter bored piles in different soils, using special drilling methods, is described. Results o1" load tests, using different test equipment, are given. Three examples are described showing how large diameter bored piles were employed for the foundations of large bridges.
865243 ,Mathematical model for vibratory pile driving Dicker, D Proc 5th Engineering Mechan&s Division Speciality Conference, Wyoming, !-3 Aug 1984 VI. P305-307. Puhl New York. ASCE, 1984 The interaction between a vertical end bearing pile and a linearly elastic foundation medium is analysed. This is one of a series of mathematical models being studied in order to develop methods of predicting the load capacity from the vibrating driving record.
865244 Dynamic effective stress response of soil structures: theory and centrifuge model studies Finn, W D L Proe 5th International Conference on Numerical Ah'thods in Geomechanics, Nagoya, I-5 April 1985 Vl. P35-46. Puhl Rotterdam: A. A. Balkema, 1985 A method for non-linear dynamic effective stress analysis is introduced which is applicable to the soil structure interaction problems. Its scope is demonstrated by analysis of a drilling island consisting of a ballasted tank placed on a submerged sand berm. Full interaction, including potential slip between tank and berm, is taken into account. Verification is provided by data from simulated earthquake tests on a centrifuged model. Auth.
~ 1986 Pergamon Journals Ltd. Reproduction not permitted