Abstract:For the environments with high pressure and enriched water of Wuhan Yangtze River Tunnel,the properties of high-durability and long-life are necessary for the segments used in shield tunneling lining structure. By means of the principle of functionally graded materials(FGM),the FGM design and optimization for reinforced concrete segment were proceeded,and the multifunction,which consists of higher impermeability of covering,higher strength of structure layer;and fire-resistant inner layer of the segments,were realized. Furthermore,the proper interface producing technology is adopted to assure the homogeneous transition of properties of different material layers,and the integrated design effects of function and structure are achieved. According to a series of tests in structure layer concrete and layer covering materials,it can be seen that the permeability of layer covering is much lower than that of the ordinary concrete and the chloride diffusion coefficient of layer covering was decreased with one order of magnitude,while the service life was increased more than ten times. It was better than the reported greatest value(6×10-13 m2/s). The mechanical properties of structure layer and layer covering are excellent and can satisfy the requirements of design. The compressive strength of layer covering concrete is C70 or above,and that of structure layer concrete is C50. The volumetric stability of layer covering and structure layer are good and the corrosion resistance is improved greatly;and the neutralization deepness of functionally graded concrete segment(FGCS) concrete is less than 1 mm. Furthermore,the fire- resistant inner layer was improved effectively by brushing fire resistance and antiknock materials,and the fire-resistant limit was 4.72 times against that of untreated samples. Finally,the service properties of FGCS were proven to be well by means of the producing and testing in factory for prefabrication.