成兰铁路茂县隧道大变形特征及施工技术

针对成兰铁路茂县隧道斜井和正洞挤压性大变形段采用常规控制措施未取得预期效果的问题，从软岩隧道大变形特征和施工技术手段入手，提出锚杆工艺改进措施，并对斜井变形情况、正洞锚杆工艺改进前后隧道变形和施工工期进行分析。结果表明： 1）大变形段水平收敛变形突出，变形时间长、速率大，斜井部分断面变形跳跃式增长； 2）斜井段变形量受断面形状影响最大，变形速率受开挖尺寸和埋深的影响最为明显； 3）锚杆施工质量对大变形控制起关键作用，可从用水量、成孔质量、水灰比和注浆方式等方面对锚杆施工工艺进行改进； 4）锚杆施工工艺调整后，段落平均变形值减小32.11%~58.86%，左右洞工期速度分别提升约172.73%和77.23%。

Large Deformation Characteristics and Construction Technology of Maoxian Tunnel on Chengdu Lanzhou Railway

The control effect of large squeezing deformation of inclined shaft and main tunnel of Maoxian Tunnel on Chengdu Lanzhou Railway is not good. Hence, the anchoring technology is improved, and the deformation status of inclined shaft and main tunnel and construction schedule are analyzed. The results show that: (1) The horizontal convergence deformation characterized by long time and high rate is prominent in large deformation section, and the deformation of partial inclined shaft shows a leap upward. (2) The deformation of inclined shaft section is affected by the shape of tunnel cross section obviously, and the excavation size and buried depth of tunnel have obvious influence on deformation rate. (3) The construction quality of anchor bolt plays a key role in controlling large deformation, and the anchoring technology can be improved from the aspects of water consumption, pore forming quality, water cement ratio and grouting method. (4) By improving the anchoring technology, the average deformation is decreased by 32.11%-58.86%, and the construction speed of left and right lines is increased by about 172.73% and 77.23%, respectively.