The Experimental Study On Hydraulic Conductivity Characteristics Of Structural Plane In The Preselected Area For Chinese High-level RadioactiveWaste Disposal

The permeability characteristic of structural plane in the fractured rock mass is one of the key issues what should be concerned in the site selection and construction of high-level radioactive waste repository. A large number of laboratory tests on the permeability characteristics of fractured rock mass had been carried out by domestic and foreign scholars. A set of device which can measure the hydraulic conductivity of structural plane was independently designed and developed on the basis of summarizing the research status of seepage in fractured rock mass and the method of gaining hydraulic parameters of fractured rock mass. The in situ water penetration tests in boreholes were undertaken on the dominating structural plane of granitic mass and F4 fault in the preselected area called Jijicao which located at Beishan,Gansu Province. Five patterns were adopted to process and analyze the data of water penetration tests. And the hydraulic conductivity of fractured rock mass in Jijicao area was qualitatively evaluated according to the results of data processing and analysis.The specific results of the research are summarized as follows:(1) A set of device which can measure the hydraulic conductivity of structural plane was independently designed and developed. The functions of module in this device are integrated, the data is collected and displayed dynamically. The device is simple, lightweight, functional agility and applicable to in situ water penetration tests in various types of geological structure. And improvement measures were proposed on further research and develop of the device for in situ water penetration tests under various coupling conditions;(2) The permeability coefficient was deduced and calculated by using Darcy law and Cubic Law. The seepage variation characteristics of structural planes, the hydraulic conductivity of fractured rock mass and the filling properties of fractures were qualitatively comprehended;(3) The data of in situ water penetration tests aimed at the rock bridge of the conjugate shear joints was processed and analyzed, the seepage variation characteristics and hydraulic conductivity of structural planes with node-type characteristics were qualitatively comprehended;(4) The data of in situ water penetration tests aimed at F4 fault area was processed and analyzed. The seepage variation characteristics and hydraulic conductivity of fault were qualitatively comprehended, and he incidence on seepage variation and hydraulic conductivity of fractured rock mass made by F4 fault was also qualitatively comprehended;(5) The method of in situ water penetration test was chosen reasonably and the rigorous test operating procedures were formulated. This provides a set of standard operating procedures for similar in situ water penetration test in the future.