A Study On Deformation Features And Control Countermeasure Of Soft Rock Tunnel

This paper investigated the deformation features and control technology of the softrock, analyzed the distribution of stress and deformation in soft rock tunnel, analyzed thedeformation features of the tunnel, optimized the parameters of excavating and supportingby applying the finite differential code FLAC3D, summed up the information constructiontechnology, based on the design and construction of diversion tunnel of Dongsonghydropower station. The work done and major achievements are as follows.The relation graph of plastic stiffness and support facilities are obtained by usinganalytical method. The analysis shows that the surround displacement and plastic stiffnessdecreased with the initial support enhanced.According to the feature of practical engineering, three-dimensional modeling wasused to analyze factors of effecting tunnel deformation. With the depth increases, the sharpincrease in tunnel surrounding displacement. The surrounding rock deformation increaseswith lateral pressure coefficient. When bias angle increased, vault crown settlement andbottom arch uplift increased. When rock strength less than or equal0.05MPa (loose bodies),the peripheral displacement becomes very large, easy to produce and rock tunnel facecollapse large deformation.By numerical simulation, deformation and plastic range will greatly reduce byapplying steps-method, and the stability of the initial tunnel excavation become veryfavorable, shows that steps-method more suitable for soft rock tunnel excavation. Steelsupport adoption curve closed at the end of the tunnel more effective than the linear closedin control rock deformation, horizontal displacement of haunch reduced about4.8%, vaultcrown settlement reduced about3.9%, floor uplift reduced about17.5%.