故宫武英殿建筑群木构件树种及其配置研究

我们从武英殿建筑群的武英门、武英殿、敬思殿、武英门东西值房、东配殿及北值房、西配殿及北值房、恒寿斋、井亭11座建筑的20余种木构件上,共采集1145个样本进行树种鉴定。结果表明,武英殿建筑群共使用了15个种或属的木材,其中有落叶松、软木松、硬木松、冷杉、云杉、黄杉、柏木、杉木、圆柏、金钱松等10种针叶材,桢楠、椴树、润楠、喃喃果、印茄等5种阔叶材。其中,杉木、桢楠和润楠是我国南方树种,喃喃果和印茄是东南亚进口材。武英殿主要承重木构件选用主要为北方树种中密度和力学强度较高的落叶松、黄杉和云杉,其他木构件则主要使用的是密度低、重量轻的软木松;敬思殿主要承重木构件使用的是云杉,其他木构件也以软木松为主,但使用的木材比较杂,角梁和爬梁全部使用了东南亚进口阔叶材;敬思殿在选材方面与武英殿的差异,可能是在光绪三十年重建时选材标准不如武英殿严格所致。武英门的木材,硬木松占了绝大多数,使用的都是强度较大的木材。所有配殿和值房的主要承重构件中,柱使用最多的是硬木松,其次是落叶松、软木松;月梁、三架梁和四架梁、瓜柱、四架梁随梁、抱头梁及其随梁木构件使用的是杉木,配殿、值房等建筑的梁没有使用强度高的木材。是以南方树种为主,其中某些主要构件还使用了珍贵的南方阔叶树种如桢楠、润楠等。这种情况表明,恒寿斋和井亭是武英殿几次大火后的仅存建筑,因而保留了明代建造时选材的历史信息。木材的使用差异具有一定的时代意义。从润楠在恒寿斋的柱和梁上,椴树、桢楠和润楠在斗棋上使用,以及根据构件的承重和位置不同进行树种配置,既考虑了对主要建筑结构材的强度要求,也考虑了尽可能减小其他木构件对主要构件的负荷,这种按照木材物理力学的性质和木材承重强度等因素进行选材的建筑原则,相当清楚地表明当时吉建筑在科学选材方面已达到很高的水平。在故宫维修工程中通过对各种木构件树种配置的研究,进行科学定性分析,将深层次地探索古建筑留给我们的历史痕迹和信息,揭示其科学性,为制定维修保护方案提供科学依据,并为故宫古建筑保护研究提供新的方法,丰富故宫历史档案资料。

A Study of the Types of Timber Used in the Hall of Martial Valour(Wuying Dian)Group of Buildings and Matching Them

We carried out individual tests on 1,145 samples from more than twenty timber structures of the 11 buildings in the complex of Wuying Dian,the Hall of Martial Valour,in the Forbidden City,(namely,Wuying Men,Wuying Dian,Jingsi Dian,Hengshou Zhai,Jing Ting and all their side structures and adjoining wings).The tests showed that of the 15 types of wood used,ten were conifers(varieties of Larix,Pinus,Picea,Tsuga and Cupressaceae,as well as Abies fabri,Pseudotsuga sinensis dode,and Pseudolarix Kaempferi)and five were broadleaf trees (Phoebe zbennan,Tilia,Machlius Nees,Cynometra and Intsia Thouars).Of these,the Tsuga,Phobe zbennan and Machlius Nees were trees that came from southern China,while Cynometra and Intsia Tbouars were imported from South-east Asia.The main weight-supporting timbers in the Hall of Martial Valour were of high density and great tensile strength,such as Larix(larch), Pseudotsuga sinensis dode('yellow fir')and Picea(dragon spruce),while other timbers were low density and light,such as softwood pine.Most of the timber used in the Hall of Martial Valour (Wuying Dian)was from north China.There were differences between Wuying Dian and Jingsi Dian,in that the main supporting timbers used in the latter were dragon spruce,while most of the other timbers were softwood pine,but there tended to be a greater mix of timber varieties, and all the corner cantilever beams and recumbent beams were broadleaf trees imported from South-east Asia.The difference may have originated when Jingsi Dian was rebuilt in the 3oth year(1905)of the Guangxu reign period when the selection of timbers was not rigorous as it had been for the Hall of Martial Valour.The timbers in the Hall of Martial Valour are almost uniformly hardwood pines of high tensile strength.Most of the side-rooms and connected rooms attached to the Hall of Martial Valour have supporting beams and columns of hardwood pine,with less larch and soft pine.The crescent beams(yueliang),third roof beam(sanjialiang), fourth roof beam(sijialiang),shorter columns(guazhu),top beams(baotouliang)and timbers running off the beams(suiliang)were China fir timber,while none of the beams in the side- rooms and connected rooms were high strength timbers.The timbers in Hengshou Zhai and Jing Ting were utterly unlike those in Wuying Dian and they were mostly southern timbers. Some important parts of the wooden structure used expensive southern broadleaf timbers such as Phoebe zhennan and Machilus Nees.This demonstrates that they were the only two structures that survived the various conflagrations that razed Wuying Dian,and that they preserve the original Ming Dynasty timbers.The dating is one of the important pieces of information relayed by the use of different timbers;from the use of Macbilus Nees for the columns and beams in Hengshou Zhai,and of Tilia(linden)and Phoebe zhennan and Machilus Nees for the roof-support bracketing,and from the use of different timbers for tasks requiring different strengths and weights,we know that there was a high level of scientific expertise in the approach to the use of timbers which took cognizance of the physical properties and tensile strengths of the timbers required for different tasks.A study of the use of timbers in major architectural projects in the construction of the Forbidden City has now been provided with an unprecedented scientific basis and will also provide valuable data for use in future dating.Revealing the scientific nature and value of the original construction will also provide a scientific basis for repair and restoration work at the Forbidden City,in conformity to the principle of 'not altering the nature of the original antiquity'.This work also provides modern data and evidence regarding the technology and materials,and lays the foundation for collecting archival material and for preservation work.