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根据场地的区域等震线资料,通过统计回归和转换的方法,得到场地的地震烈度衰减关系和地震动衰减关系,并人工合成场地未来50年超越概率10%的地震动时程,据此对取自宁夏西吉县夏家大路喜家湾滑坡后壁的黄土开展动三轴试验,研究动围压与动轴压之比,以及地震荷载的扰动作用对黄土强度的影响。研究结果表明:当动围压与动轴压之比k值较小时,k的变化对土体的强度影响较小,随着k值的增大,对于同样的破坏标准,需要更大的动应力;当k>1时,随着偏应力的增大,所需动应力减小;在低固结压力条件下,地震动会造成黄土的骨架破损,降低其强度,并且降低的程度随动荷载幅值的增大而增大;在高固结压力条件下时,较大的动应力会使土体进一步压密,产生较大的前期残余变形,但其抗剪强度有一定提高。
According to the regional isoseismic data of the site, the relationship between seismic intensity attenuation and ground motion attenuation is obtained by statistical regression and conversion method, and the synthetic time history of the ground exceeding 10% of the probability in the future 50 years is obtained The loess from the back wall of the Xijiawan landslide at Xiajiadaxia Road in Xiji County of Ningxia carried out a dynamic triaxial test to study the effect of dynamic confining pressure and dynamic axial compression ratio on the loess strength. The results show that when the ratio of moving confining pressure to moving axial pressure is small, the change of k has little effect on the strength of soil. As the value of k increases, the larger value of k When k> 1, the required dynamic stress decreases with the increase of the deviatoric stress. Under the condition of low consolidation pressure, the earthquake will cause the loess skeleton to be damaged and its strength will be reduced and the degree of decrease will follow When the consolidation pressure increases, the larger dynamic stress will make the soil further compaction, resulting in larger pre-deformation, but the shear strength will increase to a certain extent.