| 栾茂田,聂影,郭莹,王猛,刘树杰.大连饱和黏土动力特性研究[J].,2009,(6):907-912 |
| 大连饱和黏土动力特性研究 |
| Study of dynamic properties of Dalian saturated clay |
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| DOI：10.7511/dllgxb200906023 |
| 中文关键词: 饱和黏土 动扭剪试验 真空抽吸法 动剪切模量 阻尼比 |
| 英文关键词: saturated clay dynamic torsional test vacuum suction method dynamic shear modulus damping ratio |
| 基金项目:国家自然科学基金资助项目(50579006,50639010；重点项目50439010). |
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| 中文摘要: |
| 利用“土工静力-动力液压三轴-扭转多功能扭剪仪”，使用改进的真空抽吸法制备重塑饱和黏土空心试样，采用单独试样振后固结再振 加卸载 的试验方法，探讨了大连饱和黏土的动力特性．试验结果表明:在微小应变下避免孔隙水压力明显升高，使用单独试样通过改变固结压力的方法获得的最大动剪切模量 G max 和阻尼比 ξ 与用多个试样常规方法获得的结果很接近，是比较可靠的；卸压时的 G 随固结压力的减小而降低，下降的梯度比加压时的小．试验中将非接触式与接触式角位移计联合使用，以提高微小剪应变的测量精度．试验得到的归一化后的 G/G max - γ 和ξ/ξ max - γ 基本落入一个很窄的范围内，并且由 G/G max - γ和ξ/ξ max -γ 关系曲线可用公式估算出G和ξ． 采用这种单独试样振后固结再振的方法可以节省取样数量和解决土性不均匀问题，并且在试验结果可靠的基础上能够提供很多便利． |
| 英文摘要: |
| The apparatus for static and dynamic universal triaxial and torsional shear soil testing is employed to perform cyclic torsional shear test with hollow cylindrical clay specimen which is prepared by advanced vacuum suction method. The cyclic torsional shear test was conducted to measure dynamic shear modulus and damping ratio of Dalian saturated clay under different confining pressures (including increased and decreased pressure with single specimen) to replace the conventional dynamic characteristics method. Experimental results indicate that special attention should be paid to avoiding the pore water pressure′s obvious increase in slight strain. Compared with three samples in three effective confining pressures, the differential of G and ξ between two methods is closed. It is concluded that the maximum dynamic shear modulus G max and ξ obtained from single sample of cyclic simple shear test are reliable. It is also shown that the dynamic shear modulus decreases as the pressure reduces and the descending gradient is smaller than that of imposed gradient with increasing pressure. Both the gap sensor and external moment of torque transducer are used to increase the precision of small strain. Variations of normalized G/G max - γ and ξ/ξ max - γ curves fall in a narrow band and their discreteness is small. Each G and ξ can be obtained from the equations. Furthermore, this one-sample method can diminish the difference of the sample during experiment and effectively provide convenience with authentic experimental result. |
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