排序方式: 共有4条查询结果,搜索用时 15 毫秒
1
1.
In order to study the effect of freeze-thaw cycles on the type I fracture toughness of granite under ultra-low temperature conditions,semi-circular bending(SCB)specimens were used in this study,and different freeze-thaw times(1,2 and 3 times)were selected. The granite in the natural state was treated with -160 ℃ ultra-low temperature freeze-thaw cycles,and the three-point bending test was carried out on the granite after the freeze-thaw cycle. and microstructure effects. The results show that with the increase of freeze-thaw cycles,the localized damage of I-type crack tip of granite is intensified,the fracture toughness is decreased,the number of microcracks and pores in the rock is increased,the length of cracks is increased,and the pore size is increased. Finally,the changes of rock frost heaving force and fracture toughness under low temperature and ultra-low temperature conditions are compared and analyzed. Compared with low temperature conditions,the frost heaving force produced by ultra-low temperature freezing and thawing is larger. When fracture toughness decreases by approximately the same amplitude,rocks need more cycles of freezing and thawing at low temperature. The research results can provide theoretical reference for underground storage of liquefied natural gas(LNG)in ultra-low temperature environment. © 2022 Science Press (China). 相似文献
2.
西津水库网箱养殖区浮游植物特征及水质营养状态 总被引:2,自引:0,他引:2
于2006年10月至2008年7月对西津水库米埠坑网箱养殖区浮游植物进行两个年度共8次调查。第1年发现浮游植物6门53属,冬季出现种属最多,达到43属,春、夏季最少,为35属,浮游植物年平均数量为35.18×104 L-1,平均生物量为1.07 mg·L-1。第2年度采集到浮游植物6门47属,以春季出现种属最多,达到40属,夏季最少,为29属,第2年浮游植物年平均数量低于第1年,为19.77×104 L-1,生物量高于第1年,达到1.22 mg·L-1。综合营养指数评价结果显示,米埠坑网箱养殖区处于中营养水平,有向富营养化过渡的趋势。 相似文献
3.
4.
微型桩组合结构模型抗滑机制试验研究 总被引:1,自引:0,他引:1
对以空间桁架微型桩体系的组合结构采用了分级加载的方法,通过新的地质力学模型试验,研究滑坡推力引起的微型桩体系内力变化规律,并根据试验方法和空间桁架微型桩体系中各排桩的受力状态,导出了分级加载条件下受横向约束的弹性地基梁的结构分析解。试验结果表明,在碎石土地质条件下,连系梁可以有效限制微型桩顶位移,并减小桩身弯矩,滑体中桩前土压力分布相对较为均匀,各排微型桩桩体的弯矩大小分布比较接近,最大弯矩位于滑面处;基于受到横向约束的弹性地基梁的结构分析解,可以较好地描述空间桁架式微型桩在分级加载后的内力变化及其分布规律。研究结果对正确分析微型桩的抗滑机制和微型桩抗滑设计具有较好的参考价值。 相似文献
1