Study On The Performance Of The Filter Of The Water Circulation System In The Protection Engineering For The White-Crane-Girder Epigraph

The White—Crane—Girder Epigraph, which locates in the river way of Yangtze River in Northern Fuling Area in Chongqing, is a national emphasis cultural relic unit. After the construction of the reservoir in the Three—gorge is completed, the Epigraph will be submerged eternally. In order to protect this cultural relic, relevant departments intend to build a reinforced concrete container which is designed based on the conception—'unstressed container'.Clear water will be filled in the container and there is a special water circulation system which keeps the water inside and outside of the container linked, so the hydraulic pressure difference between outside and the inside is nearly null. In the mean time the water that flows into the container from the outside will be intercepted and filtered, therefore the water quality in the container can be up to the standards.The keypoint of the whole container is the water circulation system. It's primary function is:1.It can keep hydraulic pressure balance between the outside and inside which ensures the container safe and stable; 2.It can make the water quality in container limpid and transparent which is more convenient to visit . The emphases of the thesis is to study on the performance of the filter of the water circulation system which links the water inside and outside of the container. The study of the filter performance includes 3 facets:(1) Mensurating the change of turbidity in the water that flows through the filter, calculating the numerical value of turbidity diffusive coefficient and deducing the function of the coefficient and infiltration velocity. Based on the above, it can figure out the time when the turbidity will exceed the demands in the standard in certain filtering condition. (2)When the hydraulic pressure outside of the system has varied, particularly sharply, the status of hydraulic pressure in the infiltration will be, and the rule during the water level outside of the container fluctuates can be made out. The result of this item will supply the datums for the practice. (3) Figuringout the filter coefficient. In view of the water circulation system, there may be a small quantity of water leakage in practice. In the case, the filter is in the slow velocity situation, and it is necessary to do some researches on the coefficient of the filter. In this thesis, it uses two constrast methods to probe in: the experiment method and mathematical simulation method. The result of the constrast study can provide ideal mathematic models for the practice.In this thesis, through the result of the experiments, it makes out that the the hydraulic pressure difference between the outside and inside is less than 10cmH2O in the different filter conditions and the different infiltration velocities. The turbidity outside passes through the filter because of the concentration difference. Based on the mensuration result of turbidity diffusive coefficient, the time when the water quality goes beyond the standard in demand is 83.4 d which is more than 15d—the cycle period as designed. Even if there is little leakage, the time is 59.7d which is also more than 15d. The above result meets the request of the design.Through the model experiment running and the mensuration result, it can be concluded that the autocontrol valve K2 in the water circulation system is the key point according to which the hydraulic pressure balance between the outside and inside can be maintenanced when the system runs smoothily.The results and methods of the study can provide the reference for the design of the practical of the water-cycle system in the engineering.