平行顶管近接施工的室内试验研究

Laboratory Investigation on Effects of Nearby Construction of Parallel Pipe-jacked Tunnels

顶管工程中泥浆护套对顶进中的地层变形与土体劈裂有重要的影响。通过室内试验研究了近距离平行顶管的相互作用。在不同注浆条件下,将顶管顶入布置有两条既有顶管管道的试验箱内,通过测试系统获得不同注浆条件下顶管顶进时顶力的变化情况、土体的竖向变形和顶管顶进对既有顶管管道产生的影响。研究结果显示:顶管顶进过程中,顶力先增大后逐渐减小,土体出现隆起现象;新顶进顶管对既有顶管管道上方土体产生影响,但影响有限;注浆可以有效减小顶管顶进阻力,分布在顶管外壁和周围土体中的浆液使土体体积膨胀,这使得在注浆条件下土体表面产生的变形大于未注浆时土体表面变形。试验结果可以有效地指导近距离平行顶管的施工。

Slurry grouting in pipe-jacked engineering matters significantly for ground movement and soil fractu- ring. This paper investigated the inter effects of nearby construction of parallel pipelines by laboratory test. Under dif- ferent conditions of grouting, a new pipeline was jacked into the testbox where two existed pipelines were settled. From the test system, the variations of jacking force while jacking, vertical movement of soil and the influence of exis- ted pipelines while the new pipeline was jacking are obtained. The results showed that the jacking force increased first, then decreased gradually, the ground was uplifted; the new pipeline had an influence on the soil above the exis- ted pipelines, but the influence was limited; grouting is effective in decreasing the resistance while jacking, slurry was spread on the outer surface and surrounding soil which made the soil expanded, this would trigger the larger ground movement with grouting than that without grouting; these results can be used to guide the nearby parallel pipe- lines construction effectively.