Abstract: As the small opening and common seam blocking of fine cracks in hydraulic structure pose big difficulty to grouting, conventional crack grouting techniques could not guarantee the grouting quality. In this article, the shortcomings of conventional grouting techniques in chemical grouting of fine cracks in hydraulic structure are analyzed based on engineering practice. According to grouting pressure theories, the key of chemical grouting of fine cracks in hydraulic structure is to improve the groutability. On this basis, a technical idea of nondestructive and simultaneous porous grouting with high pressure is proposed, and the contents and techniques and quality control essentials of some procedures, inclusive of pasting grout nipple, crack surface enclosure, washing cracks by cleaning agent, grouting by specific equipment, simultaneous porous grouting, and raising grouting pressure, are expounded. The proposed techniques are part of and important supplement to the existing chemical grouting of hydraulic structure as they could avoid the surface damage caused by grouting holes and caulking, and improve the grouting effect.

Key words: hydraulic structure, fine crack, grout nipple, porous grouting, high pressure grouting, chemical grouting technology