南水北调工程高性能混凝土抗裂技术研究

Study on Anti-Crack High Performance Concrete Technique to the South-to-North Water Diversion Project

结合南水北调中线工程中的水北沟渡槽、坟庄河倒虹吸和漕河土渠等三个典型工程,研究提出了适合于上述工程的高性能混凝土原材料品质控制指标。对掺粉煤灰、磨细矿渣粉,以及粉煤灰与磨细矿渣粉复掺等三种不同掺和料方案的高性能混凝土进行物理、力学、耐久性、热学参数、以及配筋小梁抗弯徐变等各种性能的对比试验,提出渡槽槽身C50W6F200三向预应力混凝土宜采用单掺粉煤灰方案,倒虹吸管身C30W6F150混凝土和土渠衬砌C20W6F150混凝土可采用单掺粉煤灰方案或粉煤灰与矿渣粉复掺方案,并提出了相应的混凝土参考配合比。采用自修复抗弯试验、干缩湿胀试验、平板抗裂试验和圆环抗裂试验评价混凝土的抗裂能力,结果表明,粉煤灰方案的自修复能力较强,抗裂性较优。根据典型工程建筑物结构特点、所在地气候条件和混凝土浇筑时段等情况,结合施工现场的实地查勘,以及设计图纸等技术资料的分析,采用有限单元法的数值防裂仿真计算,提出了相应的分析结论和施工温控建议。研究了混凝土及其组成材料中Cd、Cr、Pb、As、Cu,Zn、Se等重金属离子的溶出机理及对水质的影响,其中有害重金属离子的溶出是微量的,低于相关标准规定的限量。

The quality control indexes of raw materials of high performance concrete were given based on three representative projects（Beishuigou aqueduct,Fenzhuanghe inverted siphon and Caohe earth canal in the South-to-North Water Diversion Project）.Control tests of physics,mechanics,durability,thermal parameters and flexural creep of reinforcement girder of high performance concrete with different mineral admixtures of fly ash,ground slag powder and complex of fly ash and ground slag powder were conducted.The program of fly ash should been adopted for C50W6F200 prestressed concrete of aqueduct body,and the program of fly ash or complex of fly ash and ground slag powder for C30W6F150 concrete of inverted siphon and C20W6F150 lining concrete of earth canal.The reference mixture parameters of recommendatory concrete were given.The anti-crack ability of the concrete was evaluated by self-repair bending test,drying shrinkage and wetting bulking test,plate cracking test and ring cracking test.The tests indicated concrete with fly ash has good self-repair and anti-crack ability.Some related conclusions and suggestions on construction temperature control were given by finite element numerical simulation of crack based on the structural characteristics of typical engineering,the climate property of the project site,the different placement periods of concrete,the survey of construction site,analysis of the technical materials of engineering drawings.The dissolution mechanism of heavy metal ions as Cd,Cr,Pb,As,Cu,Zn and Se in concrete and its composite materials were studied.And the effects of those ions on water quality were also studied.The dissolution of harmful heavy metal ions is a trace,and less than the maximum limit of related standard.