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为了分析盾构进出洞时隧道端部土体的失稳破坏模式,为端部土体合理加固范围的确定提供理论依据,基于颗粒流分析程序(PFC),对砂层盾构隧道端部土体的失稳破坏过程和机理进行了数值分析,并采用FLAC3D程序进行对比验证。根据土体滑动规律,给出一种对数螺旋线与直线组合的滑动破坏模式,运用颗粒流计算数据对滑动面进行曲线拟合,并进行相关性分析和显著性检验,得到颗粒摩擦因数取不同数值时的土体滑移面曲线方程。研究结果表明:隧道端部连续墙破除后,土体先在洞门附近发生局部破坏,随后土体颗粒松动破坏向内部发展,颗粒逐步发生位移重定向,最终在土体内部形成了一条显著的滑动破坏面,若隧道埋深较浅,滑动面将延伸贯通至地表;随着土体强度的增高,土体滑移直线倾角变大,对数螺旋线初始半径变小,土体破坏范围相应变小,端部土体越稳定,反之,端部土体滑移范围就会变大,稳定性变差;端部土体经过局部加固后,土体变形较小,内部不能形成滑动面,端部土体稳定性得以提高。
In order to analyze the failure mode of the soil at the tunnel end when the shield tunneling into and out of the tunnel, this study provides a theoretical basis for the determination of the reasonable reinforcement range of the end soil. Based on the particle flow analysis program (PFC) The process and mechanism of the failure of the body are analyzed numerically and compared with FLAC3D program. According to the slip law of soil, a sliding failure mode combining logarithmic spiral with straight line is given. Curve fitting is performed on the sliding surface by particle flow calculation data, and the correlation analysis and significance test are carried out to obtain the friction coefficient Soil Slip Surface Curve Equation at Different Values. The results show that after the continuous wall at the tunnel end is broken, the soil first local damage occurs near the gate, then the loosening and failure of the soil particles develop to the interior and the particles are gradually displaced and redirected. Finally, a significant If the depth of the tunnel is shallow, the sliding surface will extend through to the surface. With the increase of soil strength, the inclination of soil slip straight line becomes larger and the initial radius of logarithmic spiral becomes smaller, and the scope of soil failure corresponds to On the contrary, the slip range of the end soil becomes larger and the stability becomes worse. After the local reinforcement of the end soil, the deformation of the soil is small, and the sliding surface can not be formed inside, End soil stability can be improved.