【摘要】 地震反应分析通常采用等效非线性模型,动剪切模量G和阻尼比λ是该模型的两个重要参数。为研究目前在大型工程建设中遇到越来越多的强风化花岗岩的动力特性,利用固定-自由型共振柱(GDS RCA)对强风化花岗岩的剪切模量和阻尼比进行试验研究。GDS RCA为一种国际上广泛应用的共振柱,具有良好的性能,利用其控制试样的固结围压和孔隙水压力,可以测得试样在不同有效应力状况下的动剪切模量和阻尼比。对比研究不同有效应力下共振频率、动剪切模量和阻尼比随剪应变的变化情况,给出其变化曲线。按照Hadin-Drnevich[1]所提出的双曲线模型,拟合动剪切模量比和阻尼比随剪应变的变化曲线。利用摩擦理论,对试样阻尼的产生机制进行探讨。试验结果表明,随着剪应变的增加,试样系统的共振频率随之减小,试样阻尼比随之增大;试样的动剪切模量和阻尼比皆与试样固结时的有效应力有关,而试样阻尼比也受孔隙水压力的影响。更多还原

【Abstract】 Equivalent nonlinear model is usually applied in seismic response analysis.The shear modulus and damping ratio are two important properties in this model.Highly weathered granite is common in large engineering.It is essential to study dynamic properties of highly weathered granite.The shear modulus and damping ratio of highly weathered granite are studied with GDS resonant-column;as its the capability is excellent,it is popular in the world.The confining pressure and pore water pressure to consolidate can be controlled well by GDS RCA.After the end of sample’ consolidation,shear modulus and damping ratio can be given by experiment in the state of this effective stress.Changing confining pressure and pore water pressure,resonant frequency, shear modulus and damping ratio can be given with another effective stress.In different effective stresses,variation of shear modulus and damping ratio can be observed.And fitting curves of shear modulus and damping ratio that are put forward by Hadin-Drnevich[1] are turned out on the basis of experimental data.The authors discuss the damping mechanism of highly weathered granite sample by amfusing frictional theory.It can be seen that resonance frequency of the sample’s system has a positive correlation with shear strain, but sample’s damping ratio has a negative with shear strain.The effective stress can have impact on both sample’s shear modulus and damping ratio.However,pore water pressure can only act on damping ratio.更多还原