沉积方向对珊瑚砂动剪切模量及阻尼比的影响OA北大核心CSTPCD

Coral sand in complex geological environments exhibits significant anisotropic characteris-tics,with the sedimentation direction of the particles significantly affecting its dynamic properties.Res-onant column tests with uniform consolidation were conducted on coral sand from Nansha Islands to explore the effects of the deposition orientations(φ)(the angle between the deposition plane and the horizontal plane)and the initial effective confining pressure(σ'0)on its dynamic shear modulus G and damping ratio λ.At a given φ,the rate at which G decreased with increasing shear strain amplitude ya increased with increasing σ'0.At a given σ'0,the rate at which G decreased with increasing γa first de-creased and then increased with increasing φ,with the G-γa curve reaching its lowest position at φ=60°.Furthermore,the maximum shear modulus(G0)exhibited an initial decrease followed by an in-crease as φ increased,and the influence of φ on G0 diminished with increasing σ'0.A modified Hardin's model,which incorporated the influence of φ and σ'0,was established.The deviations between the measured and predicted G0 values were within 10％.The G/G0-ya curve was insensitive to φ,with de-viations between the measured and predicted G values by both the modified Hardin's model and Da-videnkov's skeleton curve falling within 15％.A correction term considering the influence of φ was in-troduced into the damping ratio empirical model proposed by Cheng Guoxing et al.(2006),with the deviation between the predicted and measured λ values being less than 20％.