1. The Investigation for Conserving the South-east Tower of Xue Castle in Tibet
이 프로젝트는 근세기 들어 방치되어 있던 포탈라궁 아래 콤플렉스에 대해 보호와 개발계획을 세우는 것이다. 그중
나는 동남각에 대한 조사를 맡았다. 이 프로젝트는 현재 진행중이므로 지난 여름의 조사단계 위주로 설명하도록 한다.
먼저 설성에 대해 소개하겠다.

2. Xue Castle
Xue Castle denotes the complex spaces of surrounding the east, west and south of Potala Palace.
In the 7th century, Srong-btsan sgam-po who first unified all tribes on the Tibetan plateau first built Potala palace. In the 17th century the 5th Dalai Lama made the palace extend and built Xue Castle, so Potala palace became to have the today’s appearance.

3. Inside Buildings and The Southeast Tower
Service buildings
- A horse and cow stable
- An elephant stable
- The water delivering donkey stable
- Small Factories
Government and Military buildings
- A prison
- A building of the military head quarter of Tibet
- The east and west scripture print center
-The mint
Houses
- Noble’s houses
- Servicemen’s houses
The southeast corner tower was not only a watching tower, but also the factory which produce incenses for Buddhist rituals of Potala palace.

4. First Built Year of the Southeast Tower
According to 1662 year’s a piece of painting and the early 18th Century’s a piece of wall-painting, the southeast corner tower is supposed to become to have the today’s appearance during the period of extension by the 5’th Dalai Lama from 1645 year to 1647 year.
We can conjecture that they first built the castle wall and next built the inside buildings. So this tower is a one of early buildings in Xue Castle.

5. Reconstruction of the Southeast Tower
Through long history, the almost buildings in Xue Castle have gone through several times’ repair and reconstruction.
In nearest time, the southeast corner tower was repaired in 20th century. Through this repair, the shape of building was been transformed a little, we can conjecture its change of the plan from the difference of this two photograph of roof.

6. Reconstruction of the Southeast Tower
Through long history, the almost buildings in Xue Castle have gone through several times’ repair and reconstruction.
In nearest time, the southeast corner tower was repaired in 20th century. Through this repair, the shape of building was been transformed a little, we can conjecture its change of the plan from the difference of this two photograph of roof.

7. Investigation of Existing condition

8. Investigation – materials and wall structure
The Southeast tower is the composite structure of masonry structure and wood-frame structure.
Outside walls were piled up granites or slates, and was filled the crevices with gravels, and was applied white finish coat. Inside walls generally were applied oil painting to Bagatu(巴嘎土) basic.

9. Investigation – water-proof layer
Making roofs and outside floors Tibetan give final touch with Agatu. Agatu is a sort of mortar which has good viscosity.
According to traditional method, first harden Agatu on the roof, the next coat oil on it and rub it. It’s work process need much concentration otherwise it’s performance become very poor.
In the construction of low degree’s building, generally the execution is not exquisite, so the damage from rainwater leaking is very serious.

10. Analysis of problems
1. The low water-proof performance of traditional Agatu(阿嘎土) roofs
As the other buildings in Xue Castle, the most serious damage source of the southeast tower is the leaking of rainwater. Lasa has the average rainfall of 300~500mm and most of it rain in summer. But during recent 10years Lasa’s rainfall has been increasing, so that historic buildings applying traditional Agatu on the roof have been seriously threatened.
2. The constructive problem of masonry structure
It is found that a lot of lime was being washed away near drain-pipes and spouts.
The lack of lime means that the walls lost glue bonding stones, so that a little shock could destroy the whole building.
3. The corrosion of wooden structure
The corrosion of wooden structure is not serious in the southeast tower, the damage caused by corrosion is only founded in rainwater’s leaking parts.
동남각은 설성 내 다른 건물에 비해 상태가 양호하다. 그러나 적지 않은 부분이 파괴되어 있다.~(본문)

11. Brief diagram of damage process
corrosion of wooden parts
deformation of wooden structure
Leaking of rainwater
Collapse of building
Lime plaster’s being washed away from walls
lean of masonry structure

12. Conclusion