Research On Mechanics Model Of Frost-Heaving Damage Of Concrete Lining To Small U-shaped Canal

It has become a prominent contradiction which is unbalance between demand and supply of water resources in our country with the developing of society and economic growth. So we are moving towards the water-saving agriculture and the most important imperative is to keep rational utilization of water resources in our society. The canal lining is one of the effective methods to reduce transportation water loss for agricultural irrigation. Ningxia Yellow River plain is a famous irrigation area with a long history and large amount of canals with lining have been built in recent years. Especially, U-shaped concrete lining has been widely used to ditches and bucket canals in the present stage for the construction of ecological water-saving irrigated area and the sustained development of modern agriculture because of its good at hydraulic condition and anti-frost property. However, the frost heaving injury has become a common problem so that many canals are destroyed easily or even lose the defense against seepage due to negative temperature.Thus, anti-frosting swelling of concrete lining canal has become a problem demanding prompt solution. Based on reference and analysis of various literatures, the present developing state of the impervious and frost-resisting technique was expounded in this thesis, and summarized technical measures of anti-frosting swelling damage for canal. Taking the middle and small U-shaped canal in Ningxia Yellow River district as research background, aiming at the situation that the theoretical research of mechanical features and its change rules of frost heaving damage of U-shaped concrete lining slab needed further improvement, the research work about force analysis of frost heaving damage of small U-shaped concrete lining slab and establishment of corresponding force analysis model was conducted. And aiming at the longitudinal strain caused by frost heaving of small U-shaped concrete lining structures, three-dimensional numerical simulation analysis was carried out with finite element numerical methods. The detailed research and results are as follows:(1) The main factors affecting frost heaving of concrete lining canal were discussed in this paper, and the failure mechanism and characteristics of different sections of linings were analysed according its structural type. The focuse is about two arc-plates and integral U-shaped canal linings.(2) Calculating diagram of the two types of U-shaped structures were established, which under normal frost heaving force, normal freezing force, tangential freezing force and gravity together. The mechanic model of these structures were given and the maximal tensile stress formula were worked out. The methods about determination of the position of expansion, calculation of lining plate thickness and the destruction checking of anti-frost heaving were obtained according to the anti-crack condition of the concrete plates.(3)According to a practical engineering, the numerical analysis of the integral U-shaped concrete lining canal which considered its longitudinal deformation were performed through ANSYS, and obtained the distribution about temperature field, the stress and the deformation field,which basically identical with the results of field observation. Results show that the numerical simulation of frost heaving canal is suitable and useful, and would also provide theoretical reference for canal design.