论文部分内容阅读
土的真三轴仪是研究不同应力路径等复杂应力条件下土力学性质的重要仪器.与国内外已有真三轴仪的加载机构比较,西安理工大学真三轴仪具有一室四腔、竖向和水平面内正交两向分别呈刚性和柔性加载机构的特征.试样的竖向采用刚性板加载,侧向正交双轴分别采用两组内置于压力腔的液压囊加载.针对试样上下端部刚性板的约束作用,增大了试样的竖向尺寸,研制了高宽比为2:1的压力室;针对立方体试样侧面正交双轴的液压囊体积变化量测侧向变形的不足,研制了穿越液压囊的变形量测机构;针对自动控制系统信号波动变化较大,稳定性差等不足,开发了自动控制系统及多种应力路径和控制方式的控制程序.通过饱和砂土、非饱和土和原状黄土的试验,测试了各种土的强度变化规律,验证了改进真三轴仪的性能.,The true triaxial apparatus is an important instrument, which is usually emplyed to investigate the mechanical characteristics of soils under complicated stress conditions. The new true triaxial apparatus, developed in Xi’an University of Technology, is of the rigid-flexible-flexible loading boundary system, which is different from the rigid, flexible and rigid-rigid-flexible complex loading systems at home and abroad. The chamber of true triaxial apparatus includes four cells, in which the liquid bags face two groups of orthogonally lateral surfaces of cubic specimen and top and bottom rigid plates. In the vertical direction the normal stress acts on the ends of the cubic specimen. In the two orthogonal directions, two normal stresses are applied to the lateral surfaces of the cubic specimen. To eliminate the restraint of the top and bottom plates, the height of sample increases. Accordingly, the ratio of height to width of specimen is 2:1. To measure directly the lateral deformation of the sample in orthogonal biaxial directions, a measurement element is developed by a smooth connect pole passing through the liquid bags. To reduce the fluctuation of loading signals, an automatic control system including automatic control circuit board and control program is developed by the developing software. The strength laws of saturated sand, unsaturated soil and intact loess are investigated by the true triaxial tests. The improved true triaxial apparatus is verified by the experiments of different soils.