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利用空心圆柱扭剪仪对含非塑性细粒的饱和砂土进行单调加载和循环扭剪试验,研究了不同细粒含量饱和砂土的液化特性。试验结果表明:(1)最大孔隙比与最小孔隙比均随着细粒含量的增加呈先减小后增大的趋势,分别在20%和40%时达到最小。(2)细粒含量从0%增加到20%,体积应变逐渐增加;细粒含量从20%增加到40%时,体积应变逐渐减小;之后随着细粒含量从40%增加到60%,体积应变再次增大;细粒含量超过60%以后,体积应变再次递减。(3)随着细粒含量的增加,土样的峰值强度随之降低,应力-应变关系从应变硬化特征发展为理想的弹塑性。相变角在细粒含量为30%时达到最小值。(4)细粒含量越大,达到液化所需的循环次数越小,液化时的应变越小。(5)抗液化强度曲线与抗液化应力比的变化趋势一致,在小于界限细粒含量(30%)时,随着细粒含量的增加而减小。在界限细粒含量附近(30%~50%)时,随着细粒含量的增加而增大。在细粒含量增加到60%时出现明显的骤减,之后再次随着细粒含量的增加而增大。界限细粒含量在40%左右。
The monotonous loading and cyclic torsional shear tests of saturated sand with non-plastic fine particles were carried out by hollow cylindrical torsional shear tester. The liquefaction characteristics of saturated sand with different fine-grained contents were studied. The results show that: (1) Both the maximum porosity ratio and the minimum porosity ratio first decrease and then increase with the increase of the content of fine particles, and reach the minimum at 20% and 40% respectively. (2) The volumetric strain increases with increasing the content of fine particles from 0% to 20%. When the content of fine particles increases from 20% to 40%, the volumetric strain decreases. When the content of fine particles increases from 40% to 60% , The volume strain increases again; after the content of fine particles exceeds 60%, the volume strain decreases again. (3) With the increase of the content of fine particles, the peak intensity of soil samples decreases, and the stress-strain relationship develops from the strain hardening characteristic to the ideal elasto-plasticity. The phase change angle reaches the minimum at a fine particle content of 30%. (4) The larger the content of fines, the smaller the number of cycles required to liquefy and the smaller the strain at liquefaction. (5) The tendency of the liquefaction resistance curve and the liquefaction stress ratio are consistent. When the content is less than the limit fine content (30%), it decreases with the increase of the fine content. In the vicinity of the limit of the content of fine particles (30% ~ 50%), with the increase of the content of fine particles. A significant plunge occurred when the fines content increased to 60% and then increased again with the fines content. Boundary content of fine particles in about 40%.