Abstract：Weathering prevention is one of the difficulties in earthen ruins conservation. The self-developed drip injection apparatus of chemical grouts is first applied to engineering practice to perform chemical reinforcement on the surface of Dougaeri earthen ruins No.2. The main contents include drip injection of chemical grouts in laboratory model ground，the strength characteristics of chemical grouted soil by triaxial tests，microstructures investigated by SEM observation，drip injection in field model earthen kiln，and reinforcement of Dougaeri earthen kiln No.2 by drip injection of chemical grouts. The test results show that：(1) the balloon cover injection tip specially developed for the drip injection tube can prohibits chemical grout flowing upward to the ground surface，in particular it can implement down-to-up chemical grouting on the top of underground earthen ruins due to its soft and tight attachment with the drill hole sides；(2) chemical grouts(ethyl silicate) can increase cohesion effectively，but it has little influence on the internal friction angle；(3) the thickness of chemical grouted soil by the drip injection apparatus is much larger than that of spraying chemical grouts on the surface of earthen sites；and (4) the field feasibility and adaptability of the drip injection apparatus has been verified by its successful application on strengthening Dougaeri earthen kiln No.2，which will benefit to preservation of other similar earthen ruins.
