Identification And Dividing Decay Standards Of Wood Piles At The Site Of Hai Menkou Archaeological Site

To study the wooden relics unearthed from the Hai Menkou archeological site in Dali Jianchuan, altogether 528 pieces of ancient wood samples were collected in 12 excavation unit. In this study, the conditions of suitable embedding process were optimized and the ancient wood slices were identified. Besides, using fluorescence microscope、polarization microscope and SEM technology, the microscopic structure of ancient wood was analyzed and the decay level of ancient softwood were determined. In addition, using fluorescence, two reinforcement methods of ancient wood were verified.The results were listed as follows.(1) The results of ancient wood embedding process showed that: PEG1500 was the optimal embedding reagent for slicing making. With increasing vacuum times, time for constant temperature and osmotic concentration gradient, the shear strength of ancient wood was enhanced on different extent. In conclusion, three times vacuum, 16 hours for constant temperature and gradual osmotic concentration gradient from 50% to 100% were optimal embedding conditions.(2) 528 pieces of wooden relics were identified from the archeological site. The results show that: there were 526 pieces of Pinus sp.and two blocks of Castanopsis sp. wood.(3) According to decay degree, the ancient softwood could be divided into four levels. In the first level, cells of ancient wood severely deformed, the cellulose was decomposed completely and lignin was lost seriously. In the second level, cells of ancient wood relatively serious deformed, local cellulose was decomposed in the early wood or the latewood and lignin was flowed away in the same position. Morphology of third level ancient wood cell had been relatively complete, in this level, cellulose surplus had reached the extent to support the basic wood structure and there were no cell wall separation phenomenon for individual cell structures. In the fourth level, the ancient wood was the compression wood of Pinus yunnanensis, the polarization and fluorescence phenomenon of this level wood was obvious. Besides, the corrosion degree of ancient wood was low and the integrality of chemical composition of the ancient wood was similar to the new material.(4) After the fluorescence reaction of toluidine blue suppression, it could clearly find the immersion degree and position distribution of phenolic resin and natural resin in strengthening ancient wood. Besides, compared with natural resin, many components of phenolic resin were entered into the wood cell wall which played a better role of skeleton; contrarily, natural resin mostly invaded into lumen. However, both the two methods had the phenomenon of uneven distribution of resin in different degrees in ancient wood.