浇筑方案和拆模时机对施工期大坝混凝土开裂风险的影响  

Influences of concrete placement scheme and formwork removal schedule on dam concrete cracking risk during construction period

作　　者：辛建达 胡筱 王振红[1,2,3] 汪娟 侯文倩[1,2,3] 张龑[1,2,3] XIN Jianda;HU Xiao;WANG Zhenhong;WANG Juan;HOU Wenqian;ZHANG Yan(State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research,Beijing 100038,China;Key Laboratory of Construction and Safety of Hydraulic Engineering of Ministry of Water Resources,China Institute of Water Resources and Hydropower Research,Beijing 100038,China;Department of Structure and Materials,China Institute of Water Resources and Hydropower Research,Beijing 100038,China;PowerChina Chengdu Engineering Corporation Limited,Chengdu 611130,Sichuan,China)

机构地区：[1]中国水利水电科学研究院流域水循环模拟与调控国家重点实验室,北京100038 [2]中国水利水电科学研究院水利部水工程建设与安全重点实验室,北京100038 [3]中国水利水电科学研究院结构材料研究所,北京100038 [4]中国电建集团成都勘测设计研究院有限公司,四川成都611130

出　　处：《水利水电技术（中英文）》2021年第8期38-50,共13页Water Resources and Hydropower Engineering

基　　金：国家重点研发计划项目(2018YFC0406706);国家自然科学基金资助项目(51779277);中国水科院科研专项(SS0145B712017,SS0145B612017,SS0145B392016);流域水循环模拟与调控国家重点实验室资助项目(SKL2020ZY10,SS0112B102016);三峡集团公司乌东德温度应力试验项目(WDD/0428)。

摘　　要：针对碾压混凝土坝温控措施相对简单、在温变幅度大等恶劣环境下温控防裂压力大的问题,为了提高碾压混凝土坝施工过程的安全性,提出适合大坝混凝土施工期的温控防裂措施,通过三维有限元建模,对某碾压混凝土拱坝的内部和表面温度应力仿真计算,分析了强约束区混凝土不同浇筑层厚和浇筑季节方案的可行性以及降低表面开裂风险的拆模时机。仿真计算结果表明,提高浇筑层的厚度,会增加混凝土的最高温度;随着浇筑层厚由1.5 m提高至4.5 m,高温季节浇筑混凝土最大应力较低温季节浇筑混凝土分别提高了32.2%、25.8%和26.9%,薄层混凝土的最大应力增幅受浇筑季节的影响较厚层混凝土提高5.3%。相比于夏季浇筑的混凝土,秋季浇筑的混凝土最高温度和最大应力增幅受浇筑层厚的影响更为明显,峰值应力增幅约为4.8%~5.8%。在满足混凝土拆模强度和不通水条件下,早期拆模有利于降低混凝土温降引发的应力,降低开裂风险,对薄层混凝土表面混凝土抗裂更为有利。Aiming at the problem that the temperature control measures are relatively simple during the construction of roller compacted concrete dam,and then the pressure from temperature control and cracking prevention under harsh environment with the amplitude of temperature change is larger,the temperature control and cracking prevention measures suitable for the dam concrete construction period are put forward herein,so as to enhance the safety during the construction of roller compacted concrete dam.Through the relevant 3-D finite element modeling,the inside and surface temperature stresses of a roller compacted concrete arch dam are simulatively calculated,and then the feasibilities of the schemes of different placing layer thicknesses and placing seasons of the concretes within the strongly confined zones as well as the formwork removal schedule for lowering the surface cracking risk are analyzed.The simulative calculation results show that the maximum temperature of the concrete can be increased by increasing the thickness of the placement layer;for which the maximum stresses of the concretes placed in high temperature season are increased by 32.2%,25.8% and 26.9% respectively along with the increase of the placement layer from 1.5 m to 4.5 m if compared with those of the concretes placed in the lower temperature season,while the influence of the placement season on the increasing amplitude of the maximum stress of thin layer concrete is increased by 5.3% if compared with that on the thicker layer concrete.Compare with the concrete placed in summer,the influence of the placement thickness on the increasing amplitudes of the maximum temperature and the maximum stress of the concrete placed in autumn is more obvious with the peak value of the stress increasing amplitude of about 4.8%~5.8%.Under the condition that the formwork removal intensity is satisfied and no cooling water is passed through,the formwork removal in the early stage is favorable to lower the stress caused by temperature drop and decrease the crackin

关 键 词：碾压混凝土拱坝 浇筑层厚 浇筑季节 拆模龄期 仿真计算 混凝土 安全系数 

分 类 号：TV315[水利工程—水工结构工程]