大跨软岩隧道施工动态监测试验研究

发布时间：2018-11-07 16:20

【摘要】：以内蒙古金盆湾大跨软岩隧道为工程背景,通过现场监测及数值分析,探讨围岩拱顶沉降、钢支撑内力、围岩与初期支护之间的内力、初期支护与二衬之间的内力随时间及开挖距离的变化规律,并用现有的理论及方法对其进行围岩稳定性分析。研究结果表明:对拱顶沉降数据的拟合函数进行求导分析并判定出围岩的稳定状况良好;围岩和初期支护压力在距离上台阶开挖面65 m后逐渐稳定;钢支撑外侧应力平均值大于内侧应力,最大应力值小于钢拱架的屈服强度,开挖过程安全级别始终处于安全或者基本安全状态;初衬和二衬间的接触应力在二衬浇筑后2天左右达到最大值,随后减小趋于稳定,且稳定值都小于0.1 MPa;数值模拟的围岩变形规律和实测围岩的变形规律相同且沉降实测值与模拟值差别不大,证明了模型的合理性。研究结论可为类似条件下工程的设计、施工和监测提供指导。
[Abstract]:Based on the engineering background of large span soft rock tunnel in Jinpan Bay, Inner Mongolia, through site monitoring and numerical analysis, the settlement of surrounding rock vault, the internal force of steel support, and the internal force between surrounding rock and initial support are discussed. The internal force between the initial support and the second lining varies with time and excavation distance, and the stability of surrounding rock is analyzed by existing theories and methods. The results show that the stability of the surrounding rock is good and the pressure of surrounding rock and initial support is stable after 65 m distance from the upper step excavating surface by the derivation analysis of the fitting function of the dome settlement data and the determination of the stability of the surrounding rock. The average value of outside stress of steel bracing is greater than that of inner stress, the maximum stress value is less than the yield strength of steel arch frame, and the safety level of excavation process is always in safe or basic safe state. The contact stress between the first and second linings reached the maximum value about 2 days after the two linings were cast, and then decreased to stability, and the stability values were less than 0. 1 MPa;. The deformation law of the numerical simulation is the same as that of the measured surrounding rock, and the settlement measured value is not different from the simulated value, which proves the rationality of the model. The conclusions can provide guidance for the design, construction and monitoring of engineering under similar conditions.
【作者单位】：西安建筑科技大学土木工程学院;
【分类号】：U456

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