Experimental Study On The Temperature Field And Strain Field Of The Thick Concrete Raft Foundation At Early Age

Thick concrete raft foundation is one kind of mass concrete, it is widely used in industrial and civil construction because of its good integrity and stability. But the thick concrete raft foundation has relatively thick cross-sectional, high rate of hydration, and poor thermal conductivity, making it easy to generate the internal temperature gradient, which produces thermal stress, resulting in surface or internal cracks occur on the massive concrete foundation, which affects the durability of the thick concrete raft foundation. In order to reflect the real-time changes of temperature field and stress field of the thick concrete raft foundation, the temporal and spatial distributions of the temperature field and stress field[1] of the foundation are researched. Then effective measures could be taken to prevent the occurrence of non-load cracks on the foundation, and providing evidence for the theoretical calculation and analysis.In this paper, thick concrete raft foundation of wind turbines in Hunyuan, Shanxi for the study, JRT-2-type temperature sensor and JXB-2-type strain sensor are used respectively to monitor the spatial and temporal distribution of the temperature field and strain field of the thick concrete raft foundation at early age in real time; through the analysis of the data, the nature and size of the dominant strain of the thick concrete raft foundation at early age are determined. ANSYS model is established for the analysis of the strain field of the thick concrete raft foundation under temperature effect.The test results show that:the internal temperature rise trends of each point of the thick concrete raft foundation are the same, but with different peak and peak age; the center of the foundation reaches its maximum temperature of about70℃in about4days after concrete pouring; the temperature gradient along the thickness direction of the foundation is clear; the maximum temperature difference between the top surface and center of the foundation is about40℃in9days after concrete pouring. In addition to the surface portion, other parts of the foundation are in an expanded state basically, the middle of the foundation reaches its maximum expansion value of about210×10-6in about5days。 The correlation analysis of the temperature and strain shows that:the internal strain of the foundation is mainly caused by temperature, however, the surface deformation is affected by many factors. The ANSYS numerical model simulation strain curves are in consistent with the experimental curves, when the thick concrete raft foundation is under the effect of temperature.