富水砂岩中囊式扩体锚索足尺试验研究

在现场足尺试验基础上,研究了囊式扩体锚索在兰州全风化富水砂岩中的承载特性。试验结果表明,采用水泥浆护壁方式成孔扩孔,即可以防止全风化岩塌孔,又可以将岩屑有效地置换出来。选用合适的高压旋喷压力、复喷次数、进尺速度和水灰比,能够保证扩体段扩径达到设计要求。与普通锚杆相比,囊式扩体锚索在承载力和力学性能方面均有显著提高;通过对锚索扩体段的开挖验证,承压型囊式扩体锚索对周围富水砂岩没有扰动,并且能够在防腐和耐久性方面提供明显的优势。

Full Scale Test Research on Under-reamed Ground Anchor in Water-rich Sandstone

The bearing capacity of under-reamed ground anchors in fully weathered water-rich sandstone of Lanzhou was researched based on full scale test. The test results show that the under-reaming relied on cement slurry could prevent collapse of the bored holes and could effectively replace cuttings. The under-reamed diameter well met the design requirements based on the suitable pressure, times, drilling speed of jet grouting and water cement ratio. The bearing capacity and mechanical property of under-reamed ground anchor was significantly improved in comparison with normal anchor. The surrounding of anchors in the weathered sandstone wasn’t disturbed during the construction in deep excavation, especially the anti-corrosion and durability of under-reamed ground anchor shown obvious advantages.