Field Activities for the Conservation and Sustainable Development of Ta Nei Temple in Angkor, Cambodia (Part VIII)
Tokyo National Research Institute for Cultural Properties has been providing technical support to the Authority for the Protection and Management of Angkor and the Region of Siem Reap (APSARA) for the conservation and sustainable development of the ruins of Ta Nei Temple in Angkor, Cambodia. TNRICP dispatched a total of six members including outside experts to Cambodia from December 1st to 21st, 2019 in order to report the progress of dismantling the East Gate of the temple at the meeting of the International Co-ordinating Committee for the Safeguarding and Development of the Historic Site of Angkor (ICC), and investigate causes of uneven subsidence at the basement and floor of the East Gate.
At theICC meeting at the APSARA headquarters office on December 10th and 11th, we delivered a report in association with Mr. Sea Sophearun from APSARA. Approval was granted to proceed with the conservation work further while utilizing the results of the dismantling survey, including a site visit by four specialized members of the committee. We also collected the latest information by exchanging opinions with persons in charge from APSARA, as well as experts within and outside Cambodia.
To investigate the causes of uneven subsidence, we analyzed the old ground surface, and dug the southeast and northwest internal corners till the bottom of the stone foundation to check the condition of the East Gate base. This confirmed that the East Gate basement was made of roughly formed sandstone exterior, laterite groundwork, and internal landfill. It was also determined that the entire basement structure was built on a manmade soil layer using fine grains of sand. This sand layer seems to be the one that lends stability to the foundation on which the building was constructed. Similar techniques can been observed at other temple ruins in Angkor.
After partially removing the floor pavement stone blocks, the bearing capacity of the foundation landfill was investigated with a dynamic cone penetration testing device in cooperation with Professor Dr. KUWANO Reiko from the Institute of Industrial Science, the University of Tokyo. The testing disclosed that the fragility of laterite used as base layer of the floor pavement and the strength of foundation landfill differed by location. This could be one of the causes of uneven subsidence.
Based on the outcomes of this survey, we will examine how to improve the basement structure to ensure complete restoration of the East Gate.