Analysis method for cracking and safety status of plain concrete lining with cold joints

The cold joint defect is an initial issue arising from the discontinuous pouring process commonly encountered in large-volume concrete structures, particularly in tunnel lining. However, as of now, there is no established analysis method for evaluating the stress and safety status of lining structures containing cold joints. To address this gap, we propose a comprehensive analysis method. Initially, based on the flow characteristics of concrete and the numerical calculation model for lining pouring, we introduce the interface characteristics and discrimination methods for cold joints with different pouring intervals. Subsequently, mechanical parameters of the cold joint interface are determined through a three-point bending component experiment involving concrete containing cold joints. The next step involves constructing numerical calculation models for three distinct working conditions based on on-site inspections. These models are then used to analyze the influence of cold joint defects on the stress state and deformation trends of the lining. Additionally, we discuss the damage state of cold joints within the model. Our research demonstrates the feasibility of identifying the pouring interval of cold joints by evaluating the height difference of the interface line. Notably, the height difference decreases as the pouring interval increases. Cold joint defects significantly alter the stress distribution and deformation trends of the lining. In structures with cold joint defects, the maximum stress and deformation concentrate near the cold joint area. Conventional analysis methods may lead to a misjudgment of the safety status of the lining. Under all three working conditions, there are areas where the damage value of the cold joint interface unit exceeds 0.99. This indicates that the cold joints have undergone damage failure, expanding into macroscopic cracks. Special attention should be given to cold joint defects situated near the arch waist and those with small height differences in the interface line. This article proposes an analysis process for the safety status of plain concrete lining with cold joints, which providing a basis for on-site inspection and reinforcement work.