盾构隧道功能梯度混凝土管片的研发及性能研究

DEVELOPMENT AND PROPERTIES STUDY ON FUNCTIONALLY GRADED CONCRETE SEGMENT USED IN SHIELD TUNNELING

武汉长江隧道工程所面临的高压富水环境要求衬砌结构管片具有高抗渗、长寿命的性能。引入功能梯度材料设计原理,对钢筋混凝土管片进行功能梯度设计与优化,实现管片外层高防水抗渗、结构层提供强度及内衬层耐火的多重功能。同时采用适当的界面处理技术,保证管片各功能层的性能均匀过渡,实现功能和结构一体化设计。对结构层混凝土、保护层材料性能分别进行测试,测试结果表明,保护层材料具有优良的抗渗性能,相比普通混凝土氯离子扩散系数降低一个数量级,寿命提高10倍以上,优于目前国际上已报道的最好水平(6×10-13m2/s);结构层、保护层混凝土力学性能优良,强度满足设计要求,保护层材料强度达C70以上,主体结构层达到C50;保护层材料与结构层材料体积稳定性良好;耐酸性气体腐蚀性能大大增强,90d中性化深度不足1mm;同时,管片内衬层通过刷涂防火抗爆材料有效提升了管片的内层耐火性能,耐火极限是未经处理试件的4.72倍;最后通过实际的生产及检测,进一步证明了功能梯度混凝土管片具有较好的服役性能。

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（6xl0-~3 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.