高庙子钙基膨润土饱和样强度研究

Experimental study on strength of saturated GMZ Ca-bentonite

膨润土已被首选为高放射性核废料深层处置库缓冲/回填材料的基质材料。对内蒙古高庙子地区钙基膨润土饱和试样进行了直剪试验和三轴试验研究,研究了饱和高庙子钙基膨润土强度的变化规律。直剪试验结果表明,饱和高庙子钙基膨润土峰值和残余强度随着干密度的增大而增大,随着垂直压力的增大而增大;峰值和残余时的粘聚力和内摩擦角都有随干密度增大的趋势。对直剪试验和三轴试验的强度指标进行了对比分析,固结不排水三轴剪切试验测得强度指标高于固结快剪直剪试验测的数值。

Bentonite is considered to be a possible matrix material of the buffer and/or backfill materials in the high level radioactive waste disposal repository. A series of direct shear tests and triaxial tests on saturated GMZ Ca-bentonite were performed, and the change in strength of GMZ Ca-bentonite is studied. From the results of direct shear tests, it is found that the increases in dry density and vertical pressure induce the increase in strength of GMZ Ca-bentonite. Cohesions and internal friction angles at peak and residual increase with the increasing dry density. The two different test results are compared, and thus it is found that the strength index done by triaxial test is higher than those by direct shear test.