Study On Temperature Control Parameters And Cooling Measures During Construction Of High Arch Dam

As an important dam type,arch dam has the advantages of uniform force,high stability,clear force transmission and economical saving.For arch dam construction,temperature load occupies a large proportion,temperature control and crack prevention are indispensable,especially for high arch dam.The construction of high arch dam is difficult,the construction period is long,the stress level is high,and the task of temperature control and crack prevention is more arduous.In the process of pouring concrete high arch dam,there are many factors that affect the temperature field and temperature stress during the construction period of dam.Therefore,choos:ing suitable pouring scheme is of great significance for saving engineering cost and improving the safety of dam.Based on the Mengdigou Hydropower Station proj ect and using the three-dimensional finite element method to simulate the single dam section,this paper studies and analyses the sensitivity of the pouring season,the thickness of the pouring layer,the intermittent time and the pouring temperature during the construction period of the dam body,and the influence of different heat preservation and water cooling modes on the temperature stress during the construction period,and puts forward the optimized temperature control measures for the 13#dam section.According to the simulation results,the following conclusions are drawn:In high temperature season,the highest temperature of concrete is higher,the temperature difference at the end of secondary cooling is larger,and the temperature stress is larger.At the same time,in high temperature season,using thick layer pouring can avoid the phenomenon of heat inversion,which is not conducive to temperature control and crack prevention;reducing pouring temperature helps to reduce the highest temperature of concrete,temperature difference and temperature stress;at the same time,certain protective measures can be adopted on warehouse surface and upstream and downstream surface,which can effectively reduce the surface stress of dam concrete and prevent surface cracking.In the process of water cooling,reducing the temperature of primary cooling water,increasing the flow rate and encrypting the cooling pipe can improve the cooling efficiency and reduce the temperature stress effectively,but the micro-cracks caused by the large temperature gradient around the pipe caused by the low water temperature should be avoided.Reducing the secondary cooling water temperature and increasing the flow rate can easily lead to excessive temperature stress.As the modulus of elasticity of concrete increases with age,the temperature control efficiency is higher with the increase of water cooling intensity in the early stage.At the same time,excessive cooling range and excessive cooling rate should be avoided in the secondary cooling process.