Destructive field tests on mobilization of end resistance of cast-in-situ bored piles

A series of well-designed full-scale destructive load tests were conducted on six bored piles to investigate the influence of loose debris at the pile tip on end resistance. The results show that soft debris below the pile tip will weaken the mobilization of end resistance. The ultimate tip resistance of post-grouted pile is 2.05 times that of the pile without post-grouting and the ultimate tip resistance in the second load cycle is 2.31 times that of pile in the first load cycle. The relationship between unit end resistance and displacement follows a linear model and a bilinear mode in the first load cycle and the second load cycle, respectively, whereas the unit end resistance-displacement response of post-grouted bored pile can be simulated using a bilinear mode. The critical end resistance ranges between 2 000 kN and 3 000 kN and the critical displacement ranges between 2.5 mm and 4.5 mm in the bilinear mode. As for piles rested on moderately-weathered peliticsiltstone, the socketed length has no effect on the end resistance because of the existence of loose debris.

非热处理型1120中强度铝合金绞线生产及检测

为了降低生产成本,同时保障导线的表面质量,开发了无需进行时效处理,单丝可以直接使用的非热处理型1120中强度铝合金产品。以AAAC/1120-Sulfur非热处理型1120中强度铝合金绞线生产为例,在高电导率铝导线的生产保障技术的基础上,通过再优化,改进得出一套既能保障导线机械性能和电性能均合格,又能使导线松散性符合要求的拉丝、绞线工艺方案。同时,通过实践操作及技术总结,提出一套较为完善、合理的铝合金导线松散性试验方法。