摘要
【目的】研究混凝土衬砌的温变效应,为混凝土防裂措施的选择提供参考。【方法】针对某工程泄洪洞衬砌高强硅粉混凝土浇筑后出现的裂缝,在考虑混凝土热力学参数随龄期变化及混凝土实际浇筑过程对温度应力的影响,采用三维有限元程序对衬砌混凝土浇筑全过程进行仿真分析。【结果】衬砌边墙、底板混凝土表面早期应力超过相应龄期的抗拉强度,混凝土表面将出现裂缝。泄洪洞混凝土衬砌裂缝的产生,与混凝土水化热温升高且速度快、弹性模量增长快、混凝土养护方式以及混凝土自生体积变形和干缩变形大等密切相关。采用表面保温可大幅度降低混凝土表面早期应力,防止早期表面裂缝的出现;采用低热混凝土和降低浇筑温度可改善衬砌混凝土的后期应力。【结论】采用低热混凝土、表面保温和降低浇筑温度3种温控防裂措施可以有效改善衬砌混凝土的应力状态,防止或减少裂缝的出现,在实际施工中,以低热混凝土和表面保温措施相结合效果更佳。
【Objective】 The research on thermal effect of spillway tunnel concrete lining was conducted to provide references to choose control measures for crack prevention.【Method】 According to a spillway tunnel lining concrete cracks after pouring the high strength silica powder concrete,considering concrete mechanical parameters varying with time and impacts on thermal stress of concrete pouring process,the lining concrete temperature field and stress field were analyzed by a 3-D finite element program.【Result】 Lining sidewall and footwall concrete surface early stage thermal stress exceeds tensile strength of corresponding age,so cracks would be found on the concrete surface.The cracks appeared on lining concrete is closely related to high temperature of hydration heat of concrete,fast growth of elastic modulus,concrete curing mode and large autogenous volume deformation and large shrinkage deformation.The author proposes that surface heat preservation can decrease concrete surface early stage thermal stress greatly,which can prevent surface crack;using low heat concrete and decreasing pouring temperature can improve later stage thermal stress of lining concrete.【Conclusion】 Three temperature control measures can effectively improve the stress state of concrete lining,and prevent or reduce the appearance of cracks.
出处
《西北农林科技大学学报（自然科学版）》
CSCD
北大核心
2011年第3期211-218,共8页
Journal of Northwest A&F University(Natural Science Edition)
基金
国家自然科学基金项目(50779051)
陕西省重点学科建设专项(106-00X903)
关键词
泄洪洞衬砌
硅粉混凝土
温度应力
裂缝
spillway tunnel lining
silica powder concrete
thermal stress
crack
