Study On Temperature Control And Crack Prevention Scheme Of Yangxiyuan Arch Dam

Yangxiyuan arch dam belongs to mass concrete engineering,which is facing with severe temperature change crack problems in the construction period.A reasonable and feasible temperature control and crack prevention scheme is the basic guarantee for its successful building.In this thesis,the pouring block of yangxiyuan arch dam section 6 is taken as the research object.The numerical simulation method is used to study the influence mechanism of warehousing temperature,surface heat preservation,pouring layer thickness,pouring intermittence,layout scheme of cooling water pipe,water temperature and other factors on the temperature stress of concrete,and field experiments are carried out to verify the correctness of simulation analysis.On the basis of the above,this thesis puts forward the temperature control and crack prevention scheme during the construction period of yangxiyuan arch dam,which provides the basis for the construction of yangxiyuan arch dam.This thesis consists of the following six parts:1.The influence of warehousing temperature on the temperature stress of concrete is studied by means of simulation analysis.It is found that too low warehousing temperature of upper concrete will lead to the surface cracking of lower concrete.The conclusion that the warehousing temperature is controlled within 5 ?C below the weather temperature on the day of pouring is put forward.2.Considering the requirements of thermal insulation technology,the influence of thermal insulation conditions on the temperature stress of dam concrete is studied.It is found that if the insulation layer is too thick or too thin,the temperature stress of concrete will increase.It is concluded that 2 cm thick polystyrene foam insulation board should be used for surface insulation.3.Considering the requirements of construction intermittence and construction period,the effects of pouring layer thickness and intermittence on construction period and concrete temperature stress are studied.It is found that improper pouring layer thickness and improper pouring interval will prolong the construction period and increase the temperature stress of concrete.The conclusion that the pouring layer thickness of dam 6 should be controlled for 2 m and pouring interval for 5 d is put forward.4.Considering the cooling effect of water pipe,the influence of cooling water pipe layout on the internal temperature of concrete is studied and it is found that the improper layout of cooling water pipes will be detrimental to the discharge of internal heat of concrete.The conclusion is put forward that the cooling water pipes should be arranged at the bottom of the pouring layer of mass concrete with a horizontal spacing of 1.6 m.5.The influence of water temperature on the temperature stress of concrete is studied by numerical analysis.It is found that the low water temperature will increase the temperature stress of concrete near the water pipe.The conclusion that the water temperature should be controlled to be ? 8 ?C in summer is put forward.6.At the casting site of the engineering,this thesis obtains the real temperature change data of the concrete in the pouring block through the method of arranging the temperature probe inside the pouring block of dam section 6 and compares with the temperature data of the simulation analysis to verify the correctness of this conclusion.Finally,on the basis of the above,this thesis puts forward the temperature control and crack prevention scheme during the construction period of yangxiyuan arch dam to guide the construction of the engineering.