摘要
在应力控制式三轴仪上,进行了坝料干砂、饱和砂当D_7=0.25、0.50和0.75时的不同应力水平下的浸水试验。其结果表明,单线法的轴向应变都超过了双线法干砂、饱和砂的两条应力—应变曲线之间的差值20～77％,个别竟达200％;单线法的体应变则大多数小于双线法干砂、饱和砂的两条ε_a-ε_▼曲线之间的差值,仅有54～100％。与单线法相比,双线法得出的轴向应变偏小,而体变量则偏大,说明浸水变形与应力路径有关。故用三轴仪中分别对干砂、饱和砂进行剪切的双线法来代替试样在剪切过程中浸水的单线法是不妥当的。
Deformation of upper-stream shell of core type fill dams during reservoir impounding may cause damage of dams. It is of first importance to determine the deformation character of shell materials at wetting before going to estimate the dam behaviour using numerical procedure. In this paper specimens of gravel sand from an earth dam havoc been tested in stress-controlled triaxial apparatus with two different procedures. In the first one, the specimens with natural water content are compressed to various deviatoric stress levels, and then saturated by water flow from the bottom while the stress condition remains unchanged. In the second, a pair of samples (one with natural water content and the other saturated in advance) are tested separately, and the deformations due towetting are estimated through the differences of deformation of the saturated sample from that of the unsaturated sample at the corresponding stress levels. It is concluded from the comparison of test results of these two approaches that the approach with two specimens may underestimate the axial component of deformation whereas overestimate its volumetric component at wetting in compare with the one specimen approach, which is believed to be more relevant to the in situ condition.
