护盾式TBM隧道回填层对管片受力的影响

Influence of Backfill on Force of Segment in Shielded TBM Tunnel

为了探明回填层对护盾式TBM隧道运营阶段管片受力的影响,建立考虑回填层的围岩抗力系数计算方法,为隧道设计中地层抗力系数的确定提供理论基础,设计相应的模型试验,对比了有回填层和无回填层时管片的受力特点,并采用厚壁圆筒理论推导了围岩-回填层等效弹性抗力系数的计算方法。研究结果表明:有回填层和无回填层时,管片运营阶段的弯矩、轴力、变形具有较大的差别,回填层的作用不可忽略;回填层厚度、泊松比、弹性模量、管片外半径均对围岩-回填层等效弹性抗力系数产生影响,其中回填层弹性模量为主要影响因素;回填层存在一个临界弹性模量,当回填层弹性模量大于临界弹性模量时,计算得出的围岩-回填层等效弹性抗力系数大于围岩弹性抗力系数,回填层对围岩起到增强作用,研究给出了回填层临界弹性模量计算公式,并得出回填层临界弹性模量取值与围岩弹性模量密切相关;考虑回填层的数值计算结果更接近模型试验结果,验证了围岩-回填层等效弹性抗力系数计算方法的准确性。

In order to find out the influence of the backfill on the force of the segment in the tunnel boring machine（TBM）tunnel,the calculation method of resistance coefficient in consideration of the backfill was established to provide the theoretical basis for the determination of the resistance coefficient in the tunnel design.The corresponding model tests were designed to compare stress characteristics of segments with or without the backfill.The equivalent elastic resistance coefficient of the surrounding rock and the backfill was deduced by thick-walled cylinder theory.The results show that there exist large differences of the moment,axial force and deformation of segments with or without the backfill.Hence,the role of backfill can＇t be ignored.Thicknesses of backfill,the Poisson ratio,the elastic modulus of the backfill and outside radius of the segment all have influences on the equivalent elastic resistance coefficient.Among them,the elastic modulus of backfill is the main influence factor.There is a critical elastic modulus on the backfill.When it is smaller than the elastic modulus of the backfill,the equivalent elastic resistance coefficient of surrounding rock and the backfill is much larger than elastic resistance coefficient of surrounding rock.Whilst the surrounding rock will be enhanced by the backfill.The formula of the critical elastic modulus of backfill was given in the research.It is easy to find that the critical elastic modulus of backfill is closely related to the elastic modulus of surrounding rock.The numerical results,taking the backfill into the consideration approach to the measured values,so the rationality of the calculation method of the equivalent elastic resistance coefficient is verified.