Global Sensitivity Analysis Of Influence Factors Of Maximum Temperature For Xi Luodu Arch Dam During Construction

The cracks in mass concrete has been a highly concerned problem in the engineering field.Controlling the maximum temperature of concrete is a effective way.However,the temperature of concrete will be influenced by a series of complex construction environment factors and the interaction of various factors in the process of reaching the maximum temperature.So it is difficult to find the analytical solution of the maximum temperature of concrete under such complicated conditions.In order to reveal the change rules of the maximum temperature of concrete,it is necessary to analyze the influencing factors and grasp the implicit rules of the influence factors on the maximum temperature,and then we can control the maximum temperature of concrete more effectively,which plays a guiding role in the practical construction.The traditional analysis on the influence factors of the maximum temperature of concrete is mostly based on the local sensitivity analysis method.This method only considers one factor in change,which is incompatible with the actual construction environment,and it is difficult to accurately demonstrate the relationship between the influence factors and the maximum temperature.Therefore,this paper adopts the global sensitivity analysis method to research the relationship between the influencing factors and the maximum temperature.The global sensitivity analysis method is a way to research the influence of the changes of each input factor in its space to the output of the model.The effect of input factors on the output can be studied from their whole space,and the influence of the interaction between the input factors on the output can be analyzed.Therefore,it is more suitable to analysis the influence of various factors on the maximum temperature.With the continuous maturity of dam monitoring technology and continuous improvement of management in construction scene,massive measured data has been accumulated during construction period of dam.The data not only records the change regulation of concrete temperature,but also implies the correlation between the influence factors of construction and the maximum temperature of concrete.This article takes blocks of the Xiluodu arch dam during construction period as the research object,and adopts the construction data,temperature data of the construction period of the pouring place to establish the initial database of concrete maximum temperature.The Chi Merge algorithm is used to discretize the continuous data in the database to obtain the highest temperature information system.Based on the attribute reduction theory of rough sets,the redundancy information is eliminated and the factors that have an important influence on the maximum temperature of the concrete are obtained.According to the measured maximum temperature data of each pouring block and the data of important influencing factors,the Kriging agent model method was used to establish the maximum temperature model of concrete during construction.Then,the Sobol index method was used to analyze the influence of various input parameters in their whole scope on the maximum temperature based on the established proxy model.The factors were ranked by sensitivity,the key factors affecting the highest temperature were identified.The effect of interaction between the factors on the highest temperature was analyzed.The results show that the most sensitive factor affecting the maximum temperature of concrete is the pouring temperature and the second one is the air temperature,and there is a strong interaction between the pouring temperature and the air temperature,the length of the pouring chamber,the horizontal spacing of the cooling water pipes,and the water flow parameters.In addition,the changes of the sensitivity values about various parameters under different temperature ranges were also analyzed.The results show that the total effect of air temperature rises slightly with the increase of air temperature,its effect on the maximum temperature gradually increases,and the total effect of the flow rate of the water increases gradually,indicating that the influence of the flow rate on the maximum temperature increases gradually.The total effect of the pouring temperature gradually decreased,indicating that the impact of the pouring temperature on the maximum temperature has declined.