大断面公路隧道CRD法施工影响下围岩变形规律研究

Study on Surrounding Rock Deformation Rule of Large Section Highway Tunnel under the Influence of CRD Method

以山东滨莱高速双向8车道公路大断面乐疃隧道为依托工程,采用ABAQUS软件对CRD法施工过程中围岩变形规律进行了研究,并结合现场监测结果进行对比分析。研究结果表明:1)CRD法施工过程中,地表沉降呈现出阶梯状增大规律;2)随着开挖的进行,地表沉降最大值点不断移动,全断面开挖完成后,最终地表沉降曲线呈正态分布;3)隧道开挖对地表的影响范围在隧道中心线两侧40 m左右,约为2倍隧道跨度,在该影响范围内,应加强监测;4)通过统计53个实测断面监测数据,得到浅埋段地表下沉及拱顶下沉监测值分布具有一定相似性,在类似的工程条件下,建议拱顶沉降值宜控制在30 mm、周边收敛控制在20 mm。

Based on the Yuetuan Tunnel of Binlai Expressway in Shandong Province, the largest cross-section highway tunnel in China at present, this paper studies the deformation rule of surrounding rock in the construction process of CRD method by using ABAQUS software. After comparing and analyzing the rules and the results of site monitoring, it turns out that： （1） during the construction of CRD method, theground subsidence presents a ladder-shaped increasing rule; （2） along with the excavation proceeding,the maximum point of ground subsidence is constantly moving, and the final surface subsidence curveconforms to the normal distribution after the full section excavation; （3） the influence range of tunnel excavation on the surface of the tunnel is about 40 meters on both sides of the tunnel center line, which is about 2 times the span of the tunnel. In this area, the monitoring should be strengthened. （4） According to the monitoring data of 53 measured sections, the monitoring values of ground subsidence and vault subsidence in shallow buried section are similar to each other. Under similar engineering conditions, it is suggested that the vault settlement value should be controlled at 30 mm, and the peripheral convergence at 20 mm.