高应力条件下南京砂破碎特性的试验

Experiment on particle crush mechanism of Nanjing Sand under high stress

对南京砂进行了不同终止压力下的侧限压缩试验，研究其高应力下的破碎特性．对试验前后的试样进行颗粒分析，并运用修正后的Hardin模型对其破碎进行了度量，分析了试样的粒径及级配与破碎率之间的关系．结果表明：当应力ZL20MPa增加到120MPa时，不同粒径土样发生了不同程度的破碎；粒径为0．5～1mm的颗粒在相同的应力下相对破碎Br．明显小于粒径为2～5mm的颗粒；2种不同级配的颗粒，级配良好的试样在应力为120MPa时Br为16％，而级配不良的试样在相同应力下Br为26％．因此，颗粒破碎程度随所受压力和颗粒粒径增加而增大，且颗粒级配越差颗粒破碎率越高．

The compression tests were carried out on the Nanjing Sand to study the crush mechanism under the high compresive stress with different ultimate pressures under condition of surrounding confined. To study the relationship among the crush rate and pressure, sand particle size and sand graduation, the samples were sieved before and after tests, and the crushability of the sand was quantified by modified Hardin model. It is shown that when the stress is varied from 20 MPa to 120 MPa, the samples with different sand sizes are crushed with different degrees, the crush rate （Br） of 0. 5 to 1 mm samples is smaller than that of 2 to 5 mm samples; Br of the good graduation sample is 16% at 120 MPa, BR of poor graduation sample is 26% under the same stress. So the particle crush grows up with increase of the pressure and the particle diameter, good graduation leads to lower crush rate.