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隧道位移控制基准的建立是确保隧道安全施工的一项重要内容。以厦门-翔安海底隧道陆域浅埋暗挖段CRD法施工为工程背景,陆域浅埋段总长约2525m,主要穿越全、强风化花岗岩地带,含水率高、自稳能力差。依据全站仪非接触量测获得初期支护三维绝对位移分布规律,确定三维绝对位移基准控制指标,同时对86个围岩位移监测断面的监测数据进行变形正常断面和变形异常或险情断面的位移量统计分析,最终确定CRD法(center cross diaphragm method,交叉中隔壁法)三维绝对位移控制基准。研究结果表明,将CRD1、CRD3部拱顶竖直位移和上中隔墙、下中隔墙水平位移作为CRD法位移控制指标;CRD1部和CRD3部拱顶下沉极限位移分别为200mm和130mm;CRD3部拱顶竖直位移约为CRD1部的0.5～1倍;上中隔墙水平极限位移约为100mm,下中隔墙水平极限位移约为15mm。通过现场97个断面应用,共发现58次异常和险情,由于发现及时,处置有力,保证了施工安全。
The establishment of tunnel displacement control datum is an important part of ensuring tunnel safety construction. Taking the CRD method for shallow excavation of Xiamen-Xiang’an Subsea Tunnel, as the engineering background, the shallow depth of land area is about 2525m. It mainly passes through the whole and strong weathered granite area with high moisture content and poor self-stability. According to the total station non-contact measurement, the three-dimensional absolute displacement distribution of initial support was obtained, and the three-dimensional absolute displacement reference control index was determined. At the same time, the monitoring data of 86 surrounding rock displacement monitoring sections were normal deformed, deformed or dangerous displacement Volume of statistical analysis, and finally determine the CRD method (center cross diaphragm method, cross the wall method) three-dimensional absolute displacement control reference. The results show that the vertical displacements of the domes of CRD1 and CRD3 and the horizontal displacements of the upper and middle septal walls are taken as the index of displacement control of CRD method. The ultimate displacements of domes of CRD1 and CRD3 are 200 mm and 130 mm, respectively. The vertical displacement of the dome of CRD3 is about 0.5 ~ 1 times that of the CRD1. The horizontal displacement of the upper middle wall is about 100mm and the horizontal displacement of the lower middle wall is about 15mm. Through the application of 97 sections, a total of 58 abnormalities and dangerous situations were found. Due to the timely and effective disposal, the construction safety was guaranteed.