铁路隧道混凝土强度参数取值探讨

Discussion on Concrete Strength Parameters in Railway Tunnel Discussion on Parameter Value of Concrete Strength of Railway Tunnel

现行《铁路隧道设计规范》中采用的混凝土极限强度与《混凝土结构设计规范》不一致,现行《铁路混凝土强度检验评定标准》中也没有给出混凝土极限强度的定义及检验方法,上述问题给铁路隧道结构设计带来困扰。采用调研与计算相结合的方法,对混凝土极限强度的由来和极限强度与强度标准值关系开展了分析论证,研究结果表明:铁路隧道结构设计中采用的混凝土极限强度最早来源于202组棱柱体混凝土试件的试验统计结果;混凝土极限强度与混凝土强度标准值存在数值对应关系,但两者的保证率不同(混凝土极限强度的保证率为84%,而混凝土强度标准值的保证率为95%);若铁路隧道结构统一采用混凝土强度标准值进行设计,对于钢筋混凝土衬砌无影响,对于素混凝土衬砌会导致衬砌厚度增大;《铁路隧道设计规范》中混凝土强度参与宜与《混凝土结构设计规范》中的规定相统一,这样即可保证隧道结构与其它结构的可靠性的一致性,也可消除的混凝土强度检验无标准可参照的困扰。

The ultimate strength of concrete adopted in the current Code for Design of Railway Tunnel is not consistent with that of Code for Design of concrete structures,and there is no definition and testing method of ultimate strength of concrete in the current Standard for Inspection and Evaluation of Railway concrete strength,which brings trouble to the structural design of railway tunnel.The origin of the ultimate strength of concrete and the relationship between the ultimate strength and the standard value of strength are analyzed and demonstrated by means of research and calculation.The main results are as follows:The ultimate strength of concrete used in the structural design of railway tunnel comes from the test statistical results of 202 groups of prismatic concrete specimens.There is a numerical correspondence between the ultimate strength of concrete and the standard value of concrete strength,but the guarantee rate of the two is different(the guarantee rate of ultimate strength of concrete is 84%.The guarantee rate of the standard value of concrete strength is 95%).If the railway tunnel structure is designed with the standard value of concrete strength,it will have no effect on the reinforced concrete lining,but will lead to the increase of the lining thickness for the concrete lining.The participation of concrete strength in the Code for Design of Railway tunnels should be unified with the provisions in the Code for Design of concrete structures,so as to ensure the consistency of the reliability of tunnel structures with other structures.it can also eliminate the trouble that there is no standard for reference in the concrete strength test.