Moisture content and its influencing factors of wood structures at Shuiguan Site in Jinzhongdu Watergate Site of Beijing

  Objective  The surviving wooden structures at the Jinzhongdu Watergate Site are suffering from decay, and the moisture content of the wood is a key factor in determining decay, therefore, the study of the moisture content of the wooden structure of the watergate site and the factors affecting it aims to provide a basis and reference for the conservation and repair of the wooden structures of the Jinzhongdu Watergate Site as well as the underground wooden structures of the same type.

  Method  The researchers detected the moisture content of wood at different locations of wooden structures on September 26, 2021, and had monitored the changes in wood and soil moisture content and environmental temperature and humidity at different locations of wood structures for the whole year from September 2021 to September 2022. Groundwater was detected, and experiments on the equilibrium water content of wood in soil were conducted to summarize the obtained data , and analyze the factors affecting the moisture content of wood structures and their influencing effects.

  Result  The moisture content of the exposed part of the wooden structures of the site ranged from 14.6% to 23.6%. The part of the wooden structures of the site was buried in the soil, with moisture content in the range of 30.0%−183.3%. The air temperature and humidity at the site ranged in 13−24 ℃ and 27.0%−80.0% throughout the year, respectively, and were significantly affected by the seasons. The soil moisture content of the site ranged from 1.5% to 18.0%, and the greater the depth was, the higher the soil moisture content was. The groundwater level was more than 10.0 m below the streamway surface of the site. The equilibrium moisture content of site wood in soil was linearly and positively correlated with soil moisture content, with a coefficient of determination of 0.939 9.

  Conclusion  The moisture content of the exposed part of the wooden structures of the site is in a state that the development of wood decay has stopped, and the moisture content is mainly affected by the seasonal changes in air temperature and humidity. The majority of the wooden structures in the site is buried in the soil, and their moisture content is within the range of wood decay and development. The main factor affecting their moisture content is the soil moisture content. Groundwater has almost no effect on the water content of the wooden structures of the site.