Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities
A.4 P-Y CURVE FOR SANDS (REESE ET AL. 1974)
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- Figure A P-y curve for static and cyclic loading in sand (after Reese et al. 1974).
| A.4 P-Y CURVE FOR SANDS (REESE ET AL. 1974) Reese et al. (1974) developed a p-y criterion for sand based on results of field tests, as described by Cox et al. (1984). These p-y curves are based on the power functions and are widely used in various computer programs, including FBMultipier and LPILE. Figure A shows the characteristic shape of the p- y curves for short-term static loading. The p-y curve shows four segments (i) an initial, elastic segment up to point k (ii) a nonlinear transition (from point k to point m (iii) a linear part (from point m to point u and (iv) an ultimate, constant part. 227 Figure A P-y curve for static and cyclic loading in sand (after Reese et al. 1974). The p-y curve for sand shown in Figure A can be obtained using the following procedure 1. Establish the soil friction angle Ο, soil unit weight Ξ³, and pile diameter D. 2. Calculate the following parameters for subsequent calculation as follows πΌπΌ = β 2 ; π½π½ = 45 + β 2 ; πΎπΎ 0 = 0.4; ππππππ πΎπΎ ππ = tan β β 2 οΏ½ Equation A) 3. Calculate the ultimate resistance per unit length of pile/shaft using the smaller of the values given by the following equations Equation Ab ππ π¨π¨ππ=π²π² ππ π«π«π«π«π«π«οΏ½ππππππ ππ π·π·βπ«π«οΏ½+π²π² ππ π«π«π«π«π«π« ππππππ β Equation A) For sand below the water table, the submerged unit weight (Ξ³β) should be used. ππ π π π‘π‘ = πΎπΎππ οΏ½ πΎπΎ 0 ππ tan β sin tan β β ) cos πΌπΌ +tan tan β β ) (π·π· + ππ tan π½π½ tan πΌπΌ) + tan tan β sin π½π½ β tan πΌπΌ) β πΎπΎ ππ π·π·οΏ½ 4. In Step 3, find the depth z t where there is an intersection of Equations A and A. 5. Select a depth at which a p-y curve is desired. 6. Establish y u as 3D/80. Compute p u as follows ππ π’π’=π΄π΄ π π οΏ½οΏ½οΏ½οΏ½ππ π π ππππ Equation A-25) Use appropriate values for or from Figure A, for the particular non-dimensional depth, and the static or cyclic case. π΄π΄ π π οΏ½οΏ½οΏ½ 7. Establish y m as D/60. Calculate p m as follows ππ ππ = π΅π΅ π π ππ π π ππππ ππ ππ = Equation A) π΄π΄ ππ οΏ½οΏ½οΏ½ 228 Use appropriate values for B s or B c from Figure A, for the particular non-dimensional depth, and for the static or cyclic case. 8. Establish the initial straight line portion of the p-y curve. ππ = (ππππ)π¦π¦ Equation A) Use the appropriate value of k from Table Ab Table A Representative values of k for sand under static and cyclic loading. Download 6.03 Mb. Share with your friends:
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