Study On High Pressure Grouting On Plinth Of High CFRD And Its Intelligent Pridiction And Control

With continuous upgrading and development for the height of concrete face rockfill dam in China, much attention in hydraulic engineering scope has been paid on the issues for anti-seepage ability and durability of plinth foundation impervious curtain for high concrete face rockfill dam, especially for the dam foundation rock with poor anti-seepage ability. In addition, anti-seepage safety for shallow part of impervious curtain under high water head has been a critical technique for 200m class high concrete face rockfill dam construction. As a primary measure for anti-seepage and consolidation of high concrete face plinth, grouting technique is required to be further studied and will be great meaning for dam construction technology.This study makes Shuibuya hydropower station (the first height concrete face rockfill dam of the world) and Siping hydropower station founded the whole line on weak rock of shale and sand shale as engineering background, employs large scale field simulation, adopts measures of qualitative analysis and quantitative analysis, corporation theoretical analysis and engineering application. Based on the rapid development of communication and computer technology, the study employs intelligent prediction and control technique, carries on a deep study on high pressure grouting with intelligent prediction and control techniques for plinth of high concrete face rockfill dam built on complex foundation of karst corrosion and weak shale rock layers. The major study is composed with the follows:1) Baed on research results of large-scale in-situ grouting tests of Shuibuya high CFRD and Siping high CFRD, reference to abundant research results of previous study, combined with grouting design and construction practice experience of the candidate for many years, summary and discuss are drawn on factors affecting cranny rockbody grouting effect, such as rockbody medium properties, basic fluid characteristic, and grouting construction technics, etc.2) Research work is went deep into high pressure grouting technology on plinth of a 200m-level high CFRD under the complex foundation conditions of karst corrosion layers. From points of view with structure and control, a layout of grouting boreholes which is consisted of uniform consolidation grouting and curtain grouting is put forward. A series of technical measures, such as setting up anchors, gradating to lift grouting pressure, the automatic lift monitoring-device and warning facilities are employed for lift observation on the plinth and lift deformation of the plinth during the grouting,as a result, the maximum grouting pressure in the first section of curtain grouting reaches to 1.5MPa, a satisfied grouting effect is achieved, anti-seepage abilities of shallow curtain are enhanced, and the running requirements of high CFRD under high water head within a long time period are satisfied.3) As for the CFRD of Siping hydropower station, which is wholly constructed on the weak rockbody shale and sandy shale with much obvious engineering characteristics, such as baserock with very weak lithology, many micro cranny developing , medium to weak penetrability, grouting difficulties, and impacts to rock strengthen after sunk. Aiming at the engineering characteristics above, large-scale in-situ emulating grouting tests is carried out with a success practice background of high pressure grouting technology of Shuibuya high CFRD. The study expands the application scope of high pressure grouting technology of thin plinth foundation under complex foundation conditions. Further innovation for realtime monitoring to anchor stress and examining to grouting effect is achieved.4) By the first time introducing the algorithm of Support Vector Machine (SVM) from the artifical intelligence field into grouting engineering, grouting injection prediction model is built based on LIBSVM, and better prediction results for grouting volume are achieved. Regarding checking criteria established with posterior difference, relative mean square error, and fitting accuracies as evaluating indices, the predicting precision of the model can be reflected comprehensively.5) With both phase space reconstruction theory of time series and the concept of equal-dimension-newly-information to train samples of least squares support vector machine (LS-SVM),the LS-SVM dynamic model to predict lifting deformation is set up with a reliable performance and satisfied realtime capability. Better realtime lifting deformation prediction is performed when grouting with high pressure on plinth.6) Combining SVM and fuzzy control theory, and thoughts of predictive control, a integrated intelligence system of plinth lifting deformation prediction and control is constructed, which consists of a dynamic SVM predictor and a fuzzy controller. Realize multi-step prediction of plinth lifting deformation by the dynamic SVM predictor and a decision automatically whether or not adjust grouting parameters according to the predictive results by the fuzzy controller are able to be achieved, which is in favor of boosting grouting pressure during plinth foundation grouting and insures plinth structural safety.