| The types of dam risk are summarized as seepage damage,landslide,cracking and overflow,among which seepage damage is an important type of dam risk,the destruction of earth dam caused by seepage problem accounts for a considerable proportion,at least accounting for more than 40%.The problem with the anti-seepage system is one of the main diseases of dam.The polymer grouting anti-seepage reinforcement technology combines the grouting material and the grouting theory closely together.The principle is to form a continuous 10-20m deep thin groove in the construction of the soil dam.Injection of polymer grouting material into the thin slot;The grouting material expands to fill the thin groove to form a polymer sheet,and the adjacent polymer sheets form a continuous,uniform and regular polymer impervious wall to realize the seepage prevention and reinforcement of soil dam.The main purpose of this paper is to develop a new polyurethane polymer grouting material suitable for the unstable restoration of bank slope and dam seepage environment,and to carry out the construction verification of screen type polymer flexible impervious wall in the Yangtze River and Yellow River dams respectively.This article takes the following steps to achieve this goal:（1）Firstly,the raw material types and characteristics,reaction process and mechanism of polyurethane grouting material are analyzed and summarized.The main reason of foaming rate doubling and density doubling decrease of construction foam of polyurethane grouting material in water flow（seepage）are summarized:the main component isocyanate reacts with water and releases a large amount of CO2 as foaming agent,which leads to the doubling of foaming rate;（2）The influence of different catalytic systems,molecular chain segments,flame retardants/plasticizers in the reaction system on the repolymerization of gel reaction/foaming reaction was studied;The test method of foaming expansion ratio in water were designed in this paper;At the same time,the optimal proportion of each component in the system was determined by comparing the molar ratio of-NCO/-OH functional groups and the compressive strength of the material with the surfactant content.（3）The halogen-free epoxy phosphate ester polyol was synthesized to replace the halogen flame retardant of the grouting material,and the epoxy bisphenol A structure was introduced into its molecular chain segment to enhance the rigidity of the material,and the halogen-free grouting material with high strength was developed for the repair of the instability of the slope dam.The screen type polymer flexible impermeable wall was constructed at Zhaokou sluice of Yellow River dike and Jushui River of Yangtze River dike and the return of Yangtze River dike respectively,with smooth cooperation of materials,equipment and technology.Through the comparison of different working conditions,the impermeable effect and mechanical characteristics of the polymer impermeable wall are better than those of concrete impermeable wall.In practical engineering application,the polymer impermeable wall with thickness of 1-2cm,depth of 10m and density of 160-200kg/m3 can achieve ideal impermeable effect.Bank slope and dam instability control is a long-term,huge project in our country,I believe that this material can play a role in the dam reinforcement,make a contribution.This material has high construction strength in water,good environmental performance,and good performance in repairing and lifting the sunken foundation of expressway,high-speed railway,airport runway,buildings and other infrastructure. |
