浅埋隧洞穿越不良地质段技术方案优化研究

Study on optimization of technical scheme of shallow buried tunnel crossing bad geological section

当浅埋隧洞穿越不良地质洞段,尤其是富水土洞时,极易发生塌方冒顶等事故,会对工程进度及施工成本产生影响。本文以东山供水工程为例,对塌方冒顶区的成因进行了分析,比选了冷冻法、化学灌浆法、洞内顶管法及地表注浆法,并进行了地表高压旋喷注浆工艺性试验。试验发现对于地质条件复杂的地层,土体不易被切割,难以形成连续密实的桩体,施工效果与预期效果相差很大。在此基础上,提出了"钢筋混凝土灌注桩止推墙+大管棚超前支护"的施工技术方案,并对止推墙、大管棚、开挖方式等重要环节进行了介绍,可为同类工程的塌方处理提供借鉴。

When the shallow buried tunnel passes through the bad geological tunnel section, especially the rich soil and water tunnel, it is very easy to encounterl and slide cave-in and other accidents, thereby affecting the progress of the project and the construction cost. Dongshan Water Supply Project is adopted as an example for analyzing the causes of landslide cave-in areas in the paper. Freezing method,chemical grouting method, hole inside pipe jacking method and the surface grouting method are adopted after comparison. The surface technology test of high-pressure rotary jet grouting is implemented. The test shows that the soil is not easy to be cut in the formation with complex geological conditions, it is difficult to form a continuous compaction pile, the construction effect and expected results vary widely. The construction technology scheme of "reinforced concrete cast-in-place pile thrust wall + advanced support of large pipe shed" is put forward on the basis, and the important links such as thrust wall, large pipe shed and excavation method are introduced, which can provide reference for the treatment of landslide in similar projects.