Back Analysis for Prediction of the Behavior of Laterally Loaded Single Piles in Sand   Byung-Tak Kim Doctoral Candidate, Department of Civil Engineering, KyungPook Nat. Univ., Daegu 702-701, Korea Young-Su Kim Professor, Department of Civil Engineering, KyungPook Nat. Univ., Daegu 702-701, Korea
			ABSTRACT

The purpose of the present paper is to estimate the behavior of laterally loaded single piles by back analysis of model tests. The factors considered are the effects of non-homogeneity consisting of two layers, constraint condition of pile head, lateral load velocity, relative density, and embedded length of pile on the behavior of single pile in sand. These effects are quantified by the results of model tests. Also, the model tests results are compared with the results of various numerical methods (p-y method, modified Vlasov method; new ??? parameter, Characteristic Load Method; CLM). In this study, the modulus of soil resistance and ultimate soil resistance are assumed to exponential function with depth, a reasonable assumption for Nak-dong River sand. Therefore, a new parameter equation based on the Vlasov method was derived to calculate on the modulus of soil resistance (E_h = n_hizⁿ) of exponential function with depth. The p-y method of nonlinear behavior analysis is relatively effective method of designing deep foundations subjected to lateral loads for only the reasonable of the modulus of soil resistance (E_h) and ultimate soil resistance (P_u). Therefore, the back analysis used to the determination of E_h and P_u in this study. For this, the E_h(DST) and P_u(DST) are obtained from the stress - strain relationship of direct shear test (DST). The E_h and P_u applicable to predict of lateral behavior are obtained from back analysis using p-y method with hyperbolic function. The coefficients used to modify E_h(DST) and P_u(DST) are obtained to be within the range of 0.014 - 0.05 and 0.2 - 0.4, respectively. The validity of the new ??? parameter equation is demonstrated through comparison with the results of model tests. The results of the model tests have been compared with predictions by modified Vlasov method. Very good agreement has been found below y/D = 0.06-0.14 between the tests and the predictions of the p-y method. The results show that the recommended values by Terzaghi (1955) for E_h and Reese et al.(1974) for P_u tend to under-estimate what the model test results indicate.

Keywords: lateral load, model test, parameter, non-homogeneous, p-y method, back analysis

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