新疆大石峡水利枢纽工程导流洞混凝土衬砌拆模时间研究

Study on Demoulding Time for Concrete Lining of the Diversion Tunnel of Dashixia Water Control Project in Xinjiang

大石峡水利枢纽工程导流洞长1200 m、开挖断面12 m×18 m,施工工期安排20个月,受火工品供应影响,隧洞开挖工期滞后,混凝土衬砌工期紧张;为了加快混凝土衬砌的施工进度,同时确保大断面衬砌结构强度安全,合理确定混凝土拆模时间显得尤为重要。采用FLAC3D软件建立三维模型对大石峡导流洞混凝土衬砌施工工况进行计算和分析,结合混凝土立方体抗压试验强度随养护时间变化的关系,确定边顶拱衬砌混凝土合理的拆模时间。三维数值模拟计算和试验结果表明:衬砌混凝土的强度达到25%时,其结构的变形和应力均可满足施工期安全要求,确定现场混凝土拆模时间按24 h控制,拆模后混凝土无变形。拆模时间确定合理安全,施工进度可控。

The diversion tunnel of the Dashixia Water Control Project is 1200 m long,and the excavation section is 12 m×18 m.The construction period is scheduled to be 20 months.Affected by the supply of explosives,the tunnel excavation period is lagging and the concrete lining period is tight;To speed up the construction progress of the concrete lining and ensure the safety of the structural strength of the large-section lining,it is particularly important to determine the demoulding time for concrete.The FLAC3D software was used to establish a three-dimensional model to calculate and analyze the construction conditions of the concrete lining of the diversion tunnel.Combined with the relationship between the compressive test strength of the concrete cube and the curing time,the reasonable demoulding time of the side-top arch lining concrete was determined.Three-dimensional numerical simulation calculations and test results show that when the strength of the lining concrete reaches 25%,the deformation and stress of the structure can meet the safety requirements during the construction period.It is determined that the on-site concrete mold removal time is controlled by 24 hours,and the concrete has no deformation after the mold removal.The demoulding time is determined to be reasonable and safe,and the construction progress is controllable.