旋喷桩连续施工引起的地表变形现场试验研究

旋喷法作为一种有效的地基加固方法,被应用到基坑、隧道、路基施工等多种工程领域。旋喷桩施工时,高达数十兆帕的注浆压力以及不断注入的水泥浆会对周围土体产生扰动,引起土体变形,危害周边既有结构物的安全。在宁波软土地基上进行了连续旋喷施工试验,研究了连续旋喷施工引起的周围土体的地表变形。采用了全自动全站仪对施工过程中的周边土体进行实时监测。监测结果表明,地表最大水平位移为180.31 mm,地表隆起为179.54 mm。累计地表最大垂直位移与水平位移均随与相邻旋喷桩的距离的增加而减小。在相同距离下,越靠近施工区域中心线,位移越大。基于监测结果,提出了一些减小旋喷桩施工对周边土体影响的方法。

Field-Test Study on Ground Deformation in Continuous Construction of Jet Grouting

As an effective method of foundation reinforcement, the jet grouting method is applied to various engineering fields such as foundation pit, tunnel, subgrade construction and so on. During the construction of jet grouting piles, the grouting pressure is large and the continuous injection of cement slurry will disturb the surrounding soil, causing soil deformation and endangering the safety of existing structures. Continuous jet grouting construction tests were carried out on soft soil foundation in Ningbo City, China, and the surface deformation of surrounding soil caused by continuous jet grouting construction was studied. An automatic total station is used to monitor the deformation of surrounding soil during the construction. The monitoring results show that the maximum lateral displacement of the ground surface is 180.31 mm, and the surface heave is 179.54 mm. The cumulative maximum vertical displacement and lateral displacement of the ground surface both decrease with the increase of the distance from the adjacent jet grouting pile. Under the same distance, the closer to the center line of the construction area, the greater the displacement. The completed jet-grouting piles can reduce the disturbance caused by subsequent construction of jet-grouting piles. Based on the monitoring results, some methods to reduce the impact of jet grouting construction are proposed.