Weak Surrounding Rock Research Articles

Intelligent Prediction for Distortion of Weak Surrounding Rock in Tunnel

In order to remove the hidden danger resulted by distortion of weak surrounding rock in tunnel, the GM(1,1) of the distortion data of weak surrounding rock is used to predict the distortion trend of weak rock vault in the next phase. According to the actual data, a GM(1,1) of the distortion is built, and it is shown that the predict result of GM(1, 1) is accurate, and the calamity can be reduced by the way.

Finite Element Analysis for the Displacement Characteristics of Loess Tunnel with Weak Surrounding Rock

Backed up by Dayoushan loess tunnel of Xining in Qinghai province, the displacements of vault settlement, peripheral convergence, surface deformation and post-construction settlement caused by tunnel construction are numerically simulated and analyzed. First, 2-D elastic-plastic model is founded to simulate the tunnel excavation process with up and down steps method. Second, considering the rheological characteristics of loess, 2-D visco-elastic-plastic constitutive model is founded to simulate the creep deformation of rock displacement characteristics. Finally, combined with the serious collapsible feature of loess foundation in supported project, the post-construction settlements under different conditions are simulated to obtain the settlement values of tunnel vault and bottom. The results can explain the deformation laws of tunnel displacement characteristics reasonably and show the importance of foundation reinforcement measures for loess tunnel.

Study on Mechanical Properties of Support Structure of Deep Buried Tunnel Soft and Weak Surrounding Rock in High Situ Stress Area

AbstractMechanical properties of bolt, shotcrete, steel support structure of initial support and lining concrete were analyzed through elasto-plastic 3D finite-element numerical simulation of bench tunneling in high geo-stress area. Results of analysis indicate that (1) strongly effected by steel support structure, displacement, maximum principal stress of shotcrete are larger at crown, displacement, maximum principal stress and shearing stress are larger at spandrel; (2) stress concentration strongly influenced on bolt axial stress at a range of 1.0 m surrounding rock; (3) axial stress and vertical shearing force of steel support structure increase gradually with distance augmentation to the tunnel face; (4) different principal stresses and shearing stresses exist at various layers and positions of lining. The conclusion provides a reference for deep-buried tunnel design of support structure and stability evaluation in high geo-stress area.