Applications Of Impervious Grouting In Water Conservancy And Power Works And Analysis Of Tendering Contract Modes

The country has increased amount of investment in water conservancy and power industry, and the scale of water power projects is being enlarged year by year in recent several years. Impervious works are the important component part of water power stations and reservoir works, and play a critical role in operation safety and stability of power stations and reservoirs; therefore, they attach more and more attention from the government, owners, supervisors, designers and construction units, etc.Different geologic conditions, engineering properties and purposes determine the adopted impervious foundation treatment methods. The typical impervious foundation treatment methods at home and abroad presently are: impervious concrete walls, soil cement permeation cut-off walls, combination of impervious walls and curtain grouting, curtain grouting and so on. Impervious grouting is characterized by small investment, strong universality, good effects and guaranteed construction period and quality, and has thus found extensive applications in water conservancy and power industry; e.g., the impervious curtain foundation treatment mode has been adopted for the complex large and medium water conservancy and power projects such as Sanxia permanent navigation lock 185# platform, extension of the capacity Guizhou Wujiangdu water power station, Anhui Langyashan pumped storage power station, Iluibci Qingjiang Shuibuya water power station and Pubugou water power station, etc. This paper focuses on the "normal pressure grouting process" and "opening closed high pressure grouting process" adopted for impervious grouting construction, curtain grouting construction organization, technical measures, grouting quality management experience, special problems encountered during grouting, especially solution cavity treatment methods in limestone regions, and grouting result and data analysis in the above water conservancy and power projects. Based on the study of applications of the impervious grouting foundation treatment process in water conservancy and power projects, we can select more reasonable, applicable and effective foundation treatment parameters, processes and construction organization modes as per the practical situation of each project so as to optimize construction period, investment and quality.The less reasonable contract price mode for some projects during tendering by the owner results in extremely unbalanced quotation, wasting of resources and even disputes. In view of distinctiveness of the impervious grouting foundation treatment process, it is suggested that the owner should choose an appropriate contract price mode during tendering and bidding as per geology and test conditions to effectivelycontrol cost of investment as well as to maximally eliminate unnecessary disputes and wasting of resources during execution of the contract and protect common benefits of the owner and construction unit.1. Grouting process:(1) borehole distance-affecting curtain integrity and project investment,.etc.;(2) array pitch-affecting curtain thickness;(3) adopting appropriate grouting materials and better grout proportioning--directly affecting curtain quality, grouting effect and project investment, etc.;(4) grouting process-directly affecting curtain quality, grouting effectand project investment, etc.;(5)borehole grouting effect-guide to reasonable arrangement ofgrouting construction period;(6) grouting pressure, grouting section length;(7) impervious capacity of impervious curtain;(8) determining curtain consumption in multiple formations and karst regions;(9) analysis of rock body grouting performance;(10) determining construction process, construction parameters and quality management experience in high pressure curtain grouting as well as treatment methods daring encountering relatively large solution cavities.2. Grouting construction organization(1) construction conditions;(2) general arrangement of construction;(3) general construction scheduling;(4) construction of main works;(5) treatment measures for special c...