滇中引水工程隧洞衬砌混凝土防裂关键技术研究

周世华; 覃茜; 夏求林

doi:10.13928/j.cnki.wrahe.2025.S2.055

水利水电技术（中英文） ›› 2025, Vol. 56 ›› Issue (S2) : 310 -317. DOI: 10.13928/j.cnki.wrahe.2025.S2.055

工程施工

滇中引水工程隧洞衬砌混凝土防裂关键技术研究

周世华 ¹^,² ,
覃茜 ¹^,² ,
夏求林 ¹^,²

作者信息 +

Research on key technologies for tunnel concrete crack prevention of Dianzhong Water Diversion Project

Shihua ZHOU ¹^,² ,
Xi QIN ¹^,² ,
Qiulin XIA ¹^,²

Author information +

文章历史 +

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摘要

输水隧洞二衬属于典型的强约束薄壁钢筋混凝土结构，目前尚无薄壁大体积混凝土防裂技术规范，防止隧洞二衬混凝土开裂历来是工作中的重点和难点。本文依托滇中引水工程，从裂缝成因、混凝土性能调控、温控防裂技术等方面开展试验与计算分析，研究滇中引水工程隧洞衬砌混凝土防裂技术。研究表明，工程部分洞段衬砌混凝土产生环向裂缝和水平向不规则裂缝的主要因素是混凝土单位用水量高、基础温差大引起的；为降低混凝土单位用水量，工程人工砂MB值应不大于1.0 g/kg,当超过时，应采用清洗法或掺入抗泥剂以降低人工砂黏土物质的不利影响；隧洞衬砌混凝土的抗裂安全度应不小于1.65,施工时温度对抗裂安全度影响最大，基本工况下衬砌混凝土的最小抗裂安全度均小于1.65,应对混凝土浇筑温度、最高温度加以限制，以降低开裂风险；高温季节施工或结构缝分缝长度过长时，可采用外掺氧化镁的微膨胀混凝土，使混凝土28 d自生体积变形超过30×10^-6,最小抗裂安全度可超过1.65,开裂风险较低。

Abstract

The secondary lining of water conveyance tunnels is a typical thin-walled, strongly constrained reinforced concrete structure. Currently, there is no specific technical code for crack prevention in thin-walled, large-volume concrete structures. Preventing cracks in tunnel secondary linings has long been a key technical challenge. Based on the Dianzhong Water Diversion Project, this study conducted experimental investigations and computational analyses on crack prevention technologies for tunnel lining concrete, focusing on crack formation mechanisms, concrete performance optimization, and temperature control measures. The result indicate that the primary causes of circumferential and irregular horizontal cracks in some tunnel sections are excessive concrete water content and significant temperature gradients between the concrete and its foundation. To reduce concrete water demand, the MB value of manufactured sand should not exceed 1.0 g/kg. If this threshold is exceeded, washing or adding antimud agents is recommended to mitigate the adverse effects of clay content in the sand. The crack resistance safety factor of tunnel lining concrete should be no less than 1.65. Among influencing factors, temperature during construction has the most significant impact on crack resistance. Under standard construction conditions, the minimum crack resistance safety factor typically falls below 1.65; therefore, it is necessary to control both the pouring and peak temperatures to minimize cracking risks. During construction in high-temperature seasons or when structural joints are excessively long, micro-expansion concrete with added magnesium oxide can be used. This ensures that the autogenous volume change at 28 days exceeds 30 × 10^-6, raising the crack resistance safety factor above 1.65 and effectively reducing the risk of cracking.