Effect of Pore Fluid Pressure on the Normal Deformation of a Matched Granite Joint

Qiang Zhang ^1,2, Xiaochun Li ^1,*, Bing Bai ^1,*  , Shaobin Hu ³ and Lu Shi ¹

^{1 State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China}

^{2 University of Chinese Academy of Sciences, Beijing 100049, China}

^{3 College of Civil and Transportation Engineering, Hohai University, Nanjing 210098, China}

Abstract

The influence of pore fluid pressure on the normal deformation behaviors of joints is vital for understanding the interaction between hydraulic and mechanical processes of joints. The effect of pore fluid pressure on the normal deformation of a granite matched joint was investigated by laboratory experiments. Experimental results indicate pore fluid pressure significantly affects the normal deformation of jointed sample, and the relative normal deformation of jointed sample during fluid injection consists of the opening of the joint and the dilation of host rock. The action of pore fluid pressure on the joint follows the Terzaghi’s effective stress law. The normal deformation of the joint can be well quantitated by the generalized exponential model. The relative normal deformation of host rock during fluid injection would have a linear relationship with pore fluid pressure, and if affected by gas is more pronounced than water.                                                                                                               

Keywords:  laboratory experiment;  pore pressure;   hydro-mechanical coupling;   fracture closure;       constitutive model;   effective stress

processes-06-00107.pdf

http://www.mdpi.com/2227-9717/6/8/107