Research On Pulsating Grouting Technology Of Water Leakage Plugging And Leakage Of Strong Weathering Dam Foundation

Curtain grouting is an important means of anti-seepage for dam foundations.Although many dams in China have been treated with conventional cement curtain grouting,it is gradually found that some dam foundations still have leakage problems of varying degrees.There are many reasons for this,such as the aging of materials in the dam area,the seepage and corrosion of high-pressure water,the complex and diverse geological conditions and the single construction process,the consideration of the structure affecting the grouting pressure or the lack of grouting,the lack of grouting quality,and the reduction of the durability of the grouting curtain,etc.Among them,the most common situation is that the stratum is complex and diverse and the construction technology is single,which makes the anti-seepage system ineffective.In this paper,taking the Bachi Reservoir in Yunnan as an example,the research on the application of new technology for its strongly weathered dam foundation is carried out.The Bachi Reservoir in Honghe Prefecture is a new water source project in Lvchun County.Construction started in 2015.In 2017,the face rockfill dam began to store water.With the rise of the reservoir water level,the seepage of the dam foundation gradually increased.After the reservoir was emptied twice,the conventional grouting method was adopted.The dam foundation is grouted and reinforced,and the maximum water seepage is still 0.1m3/s.Summarizing the general situation of the Bachi Reservoir project and the seepage situation,a comprehensive leakage analysis was carried out on the geological conditions of the dam base,the grouting conditions of the toe plate,and the previous grouting results.Under the condition that the slab grouting pressure and lift are not well controlled,the conventional grouting methods of the Bachi Reservoir must have technical problems such as poor grouting,difficulty in forming holes,uncontrollable grouting range,local grouting,and poor uniformity of the curtain wall.According to its geological characteristics and the existing leakage situation,a new construction method is proposed to carry out effective grouting treatment.The main or results are as follows:(1)Find out the main penetration areaUsing the geophysical detection combined with the previous special on-site drilling water pressure test and the observation records of the on-site water level well,the results of the three revealed that the main seepage areas of the dam are concentrated between the toe boards and the bank slope on both sides of the dam,and the original grouting curtain under the toe board of the right bank There are obvious defects,especially the shallow part of the curtain within 15m below the toe plate,the water penetration is much greater than 5Lu,and it can be judged and determined to be the main relatively concentrated strong seepage zone where the large curtain is generated in the dam foundation of the Bachi Reservoir.(2)In view of the complex geological conditions of the Bachi Reservoir and the difficulties in grouting technology,a new technology,"the bottom-up pulse technology of drilling holes" is proposed.Indoor material tests for the new technology were carried out,and three materials were studied,namely ordinary cement grout,which is used for pulse grouting under the condition of no moving water above the reservoir water level;fast-setting stable grout,which is used for pulse grouting under dynamic water conditions below the reservoir water level;It is used for the pulsed slurry in the hole section with a large injection rate.Proposes the"introduction hole bottom-up small-segment pulse technology".Conventional grouting often controls the lifting deformation and the amount of pouring through the grouting pressure,while the new technology controls the grouting pressure through the lifting deformation and the amount of pouring.To ensure that the lifting deformation and the amount of grouting can be controlled when grouting each hole section,and the maximum grouting pressure can be used.Conduct field tests on new technologies,record the test process,solve problems encountered in the test,analyze the test results,and adjust the process and parameters.To ensure that the new technology can be fully used in the grouting of the dam foundation of the Bachi Reservoir.(3)Comprehensive construction application of new technology and dynamic optimization of constructionAfter the test,the new technology "the bottom-up small-section pulse grouting technology of the pilot hole" was applied to the comprehensive construction of the Bachi Reservoir for seepage prevention and plugging;considering the cost saving,dynamic optimization was implemented in the overall construction process,and the construction area was divided into,during the construction process,various data are drawn into charts,such as water pressure data,irrigation amount,grouting pressure,etc.,you can visually see the grouting situation of each part of the area,analyze its grouting ability,and judge whether the surrounding blocks can be adjusted grouting In this way,a large number of grouting hole sections can be reduced,and the grouting can not only be poured into the area that really needs to be poured,but also save the cost and shorten the construction period to a great extent.The data of engineering examples show that the new construction method can not only meet the anti-seepage effect while making up for the shortage of conventional grouting,but also has significant advantages in reducing costs and speeding up the progress.It can be extended to more similar projects.