TBM隧道豆砾石-地层抗力系数计算方法研究

豆砾石回填与灌浆技术在护盾式TBM施工的隧道中获得了广泛应用,但是豆砾石填充层对地层抗力系数以及管片结构受力的影响有还有待研究。本文利用厚壁圆筒弹性应变理论和温克勒假设,首先建立轴对称条件下的豆砾石-地层抗力系数公式并对影响该公式的因素进行了分析。在此基础上,考虑了豆砾石填充层的非均匀分布,建立了非轴对称条件下的豆砾石-地层抗力系数公式。研究表明:(1)是否考虑豆砾石填充层的存在以及豆砾石填充层是否均匀分布对地层抗力系数具有重要影响;(2)不同岩性条件下,豆砾石填充层弹性模量均存在一临界值使豆砾石-地层抗力系数的性质发生突变;(3)豆砾石填充层厚度的增加则具有强化豆砾石-地层抗力系数性质的作用。

Research on the Calculation Method for Pea Gravel Backfilling Layer and Ground Reaction Coefficient of TBM Tunnel

The construction technology of gravel backfilling and grouting has been widely applied in TBM tunnel, but further study is required on the effect of pea gravel backfilling layer on the ground reaction coefficient and the mechanical characteristics of TBM segment. The author first puts forward a formulation for pea gravel backfilling layer and ground reaction coefficient in the condition of axisymmetry with the elastic theory of thick-wall cylinder and winker assumption. Furthermore, the influential factors of the formulation are discussed. Then the formulation for pea gravel backfilling layer and ground reaction coefficient in the condition of nonaxisymmetry is put forward taking the maldistribution of pea gravel backfilling layer consideration. The study suggests that:(1)It is very important for ground reaction coefficient whether or not taking the existence of pea gravel backfilling layer and the maldistribution of pea gravel backfilling layer consideration;(2)Under the different lithologic conditions, there is a threshold of modulus of elasticity of backfilling layer which leads to discontinuous behaviors of pea gravel backfilling layer and ground reaction coefficient;(3)The increase of the pea gravel backfilling layer’s thickness plays an important role in strengthening the characteristic.