临海隧道混凝土结构耐久性和使用寿命研究

Study on durability and service life of concrete structure of coastal tunnel

通过模拟临海碳化环境和硫酸盐侵蚀环境,对不掺掺和料(P)、单掺粉煤灰(M)和复掺粉煤灰和矿渣(N)三种配合比混凝土进行了相关耐久性试验,研究了碳化后、硫酸盐侵蚀后、碳化和硫酸盐耦合作用下,不同配合比混凝土抗水渗透、抗氯离子渗透和抗压强度变化规律.研究结果表明:1)碳化后,混凝土的抗水渗透能力变强,抗氯离子渗透的能力降低,抗压强度增加,混凝土氯离子扩散系数和抗压强度与碳化深度呈幂函数关系.2)在硫酸盐侵蚀过后,混凝土的抗水渗透能力变弱,抗氯离子的渗透能力降低,抗压强度增加(跟56d比较),硫酸盐浓度从0.5%、5%、15%依次增大时,抗压强度增幅减小;3)在碳化和硫酸盐的耦合作用下,混凝土抗氯离子的渗透能力降低,抗压强度值增加.以拱北隧道暗挖段钢筋混凝土衬砌结构为背景,对混凝土结构进行使用寿命预测,研究发现N配合比结构混凝土(保护层厚度0.06m)使用寿命为352a,使用寿命最长,其次是M,最小为P.

This study conducts a durability test using three types of concrete with admixture of non-doped (P),single fly ash (M),and a compound of fly ash and slag (N) to simulate coastal carbonation and sulfate environment.Based on this,after carbonation,erosion of sulphate,and coupling action of carbonization and sulfate attack,resistance to water seepage,resistance to chloride ion penetration and compressive strength of concrete with different ratios of concrete are studied respectly.Results are as follows.1) After carbonization,resistance to water permeability on concrete reinforces,resistance to chloride ion penetration decreases,and the compressive strength of concrete increases.The chloride diffusion coefficient of concrete and compressive strength are the power function of the carbonation depth.2)After sulfate attack,resistance to water permeability on concrete reinforced weakenes,resistance to chloride ion penetration decreases,and the compressive strength of concrete increases (compared with 56 d).The increases amplitudes of the compressive strength is reduced with the increase of sulfate concentration at 0.5%,5% and 15%.3) After the coupling effect of carbonization and sulfate attack,resistance to chloride ion penetration decreases and the compressive strength of concrete increases.The reinforced concrete lining structure tn the hidden digging section of Gongbet Tunnel is used as the engineering background.The service life of a concrete structure is predicted using the calculation model.This re search shows that the service life of a concrete structure with N is 352 years,which is the longest service life span,the concrete structure with M is second,and P is the worst.