硅藻土隧道基底加固方法现场试验研究

Field Test Study on Reinforcement Method of Diatomite Tunnel Base

依托杭绍台高铁飞凤山隧道工程出口外场地硅藻土地段,进行高压旋喷桩和钢管桩的现场试验,对比分析成桩完整性、均匀性、极限承载力及经济性等指标。结果表明:旋喷桩成桩在硅藻土地层中离散度较大,成桩效果并不理想,取芯抗压强度按埋深分布差异较大,存在强度分布不均匀的现象,会引起地基承载力的降低,而钢管桩试桩中仅极少数存在轻微缺陷,成桩效果佳;硅藻土地基中钢管桩试验的Q-S、P-S曲线呈陡降型,且位移回弹量很小;钢管桩在卸荷后沉降量小,说明其在硅藻土抗沉降能力强,适应性好;从经济性角度,钢管桩比旋喷桩施作流程更简便,对环境影响更小,更经济环保。

Belying on the diatomite soil section outside the site of the Feihuangshan Tunnel exit of Hangzhou—Shaoxing—Taizhou high-speed railway, the field tests of high-pressure jet grouting piles and steel pipe piles are carried out. It compares and analyzes the pile integrity, uniformity, ultimate bearing capacity and economy. The results show that: the dispersion of jet grouting pile in diatom soil layer is large, and the effect of pile forming is not ideal. The compressive strength of core varies greatly according to the buried depth, and the uneven distribution of strength exists, which will reduce the bearing capacity of foundation. However, there are only a few slight defects in the test pile of steel pipe piles, and the pile forming effect is good. The Q-S and P-S curves of steel pipe piles test in diatom soil foundation are steep drop type, and the displacement rebound is very small. The settlement of steel pipe piles after unloading is small, which indicates that it has strong anti-settlement ability and good adaptability in diatomite. From the economic point of view, the construction process of steel pipe piles is simpler than that of jet grouting pile, with less impact on the environment and more economical and environmental protection.