Effect Of Poisson’s Ratio Of Core Clay On Dynamic Settlement Of The Earth Dams

Abstract

Construction earth dam is developed to access supply resources. This paper tried to evaluate numerical analysis of the dynamic settlement during the earthquake in different conditions of the Poisson's ratio from core clay. Models were carried out with NAGAN record. ANSYS software is used regard to Finite-element method. Literature indicated that the maximum displacement during the earthquake is conducted at the crest. Interaction between dam and foundation is cased it. Lateral strain is administered the zero so models were considered in plan strain method. This paper considered end of construction with fill up reservoir when the core clay is saturated. Effect of Poisson's ratio on maximum settlement is evaluated. It was regarded the range between 0.2-0.45 for saturate and un saturate respectively. Results indicated that increase of the Poisson's ratio for saturate condition was caused to reduction of the maximum settlement at the crest and middle of core. It is mentioned the end of construction was at the critical state. Due to design of the earth dam regard an increase of construction, control dynamic settlement is required because there are good samples was damaged during the earthquake. Therefore, it is concerned to evaluate and best researches about influence of the dynamic load settlement in the earth dam during an earthquake. Literature review indicated that since the beginning of 1920s and up to 1960s 'Pseudo-static method' of analysis was well-known. However, this method was very simple, and it could not account on the nature of the slope-forming material or the foundation material. Based on deformation characteristics, NEWMARK (8) was proposed 'Sliding block method'. Among other methods, 'Shear beam model' analysis was quite popular. This method was introduced by MONONOBE (7). GAZETAS (3) proposed an improved 'Inhomogeneous shear beam model' which can take care of the fact that the shear modulus in earth or rock-fill dams is not constant but increases with 2/3 power of depth from the crest. CLOUGH and CHOPRA (2) were introduced the finite-element method for two-dimensional plane-strain analysis to estimate the dynamic response of an embankment assuming that it consists of linearly elastic, homogeneous, isotropic materials. Later, several other researchers developed the finite element and finite difference method for non-linear, inelastic, non homogeneous, anisotropic behavior of materials under seismic conditions. ZEGHAL and ABDEL- GHAFFAR (13) were proposed a local-global finite element method of analysis for determination of the non- linear seismic behavior of earth dams. Ming and Li (6) conducted a fully coupled finite-element analysis of failure of Lower San Fernando dam and examined the possible reason of the dam failure. Quick development of computer programs had a useful information of earthquake engineering research. For example, several computer programs like (4, 5, 9and12) were used worldwide for the intensive seismic analysis of the earthen dam. SEID- KARBASI and BYRNE (11) and PIAO et al(10) were represented the dynamic analysis of the earth dams using the finite difference method based computer code FLAC. ZHU et al (1) have presented a two-dimensional analysis of embankment using finite element based program PLAXIS. Shortly, the maximum displacement during the earthquake is induced at the crest. Interaction between dam, and foundation is caused it. This paper considered the effect of Poisson's ratio on maximum settlement at the end of construction regard to two conditions. The first is represented the un saturated dam and second is conducted to saturated dam when it is coupled the reservoir. Briefly, this paper was evaluated the effect of Poission's ratio in clay core on dynamic settlement of the earth dam. II.