Field Survey on the construction time, the heritage registration and the stability of the Longyou Caves in Zhejiang Province, China

本研究的目的是澄清1992年在中国浙江省龙游发现的五个巨大地下洞口周围岩石的退化和风化状态。几位当地历史学家指出，它们大约建于2300 - 2400年前（春秋时期）。我们需要通过岩石力学和保护科学进行以下研究：1)地质调查：除地形和地质调查外，还应用了电法（电阻率法）。详细研究了其地质构造、开口、断裂和裂缝的构造。2)地下洞口的尺寸：代替传统的激光穿越，这被认为需要非常长的时间。调查时，采用最新的3d扫描仪系统。在一周内测量了四个开口的精确尺寸。3)岩石的物理性质：从岩石的表面和孔壁上采集岩石样品，从颗粒分布、可溶性、矿物成分、差热行为、比表面积、孔径、盐渍化和生物风化作用等方面进行分析。黏土矿物溶解度和溶胀压力是影响风化过程的主要因素，氢离子浓度的变化可以作为表征黏土矿物风化过程的重要指标。4)洞穴环境监测：连续两年测量温度、相对湿度、照度、气压。建立了地下洞口环境数据库。根据这次调查和各自洞口上方地面的电阻率分布，我们建议当地政府（负责保护洞口）拆除几个用来招待游客的人工水库。水库渗水明显加速了风化破坏。5)沉积物分析：确定开口的施工时间是我们的关键问题。由于海关规定，不允许运输从开口底部取样的疯狂沉积物。总之，我们发现电阻率法、三维激光扫描和氢离子分析的应用是非常有用的，通过非破坏性的方法、调查和综合信息，成功地建立了新的途径来调查有价值的遗址。少

The objective of this research is to clarify a state of deterioration and weathering of rock, surrounding the five huge underground openings which were found in Longyou, Zhejiang Province, China, 1992. Several local historians pointed out that they were constructed approximately 2,300-2,400 years ago (the Spring-and-Autumn Period). We needed to study through rock mechanics and conservation science as follows:1) Geological survey: In addition to topography and geological surveys, the electric prospecting (Electric Resistivity Method) was applied. The geological formations, structure of the openings, faults and fissures were investigated in detail.2) Dimensions of the underground openings: Instead of a conventional laser transit, which was considered to require a tremendously long time for. survey, the latest 3D-Scanner system was employed. The precise dimensions of four openings were measured in one week.3) Physical properties of rock: Rock specimens were sampled from the surface and th … More e wall of openings, and analyzed from the points of view on particle distribution, slakability, mineral components, differential thermal behavior, specific surface area, pore size, salinization and biological weathering effect. We concluded that swelling pressure and solubility of clay minerals are main causes in weathering process, and a change of hydrogen ion concentration can be a good indicator for characterization.4) Environmental monitoring in caves: Temperature, relative humidity, illuminance, and barometric pressure have been measured continuously over two years. We establish the data base for the environment of the underground opening. from this survey and the distribution of electric resistivity in the ground above the respective openings we suggested the local government (charged in preserving the openings) to remove several man-made reservoirs which were supposed to entertain visitors. The seeping water from the reservoirs remarkably accelerated weathering damage.5) Analysis of sediments: it was the key issue for us to identify a construction time of the openings. Due to the custom regulations it was not allowed to transport the mad sediments which had been sampled from the bottoms of the openings.Above all, we found that the application of the Electric Resistivity Method, the 3D Laser Scanning, and the hydrogen ion analysis were very informative, and it was successful to establish the new access to investigate valuable heritage sites through the non-destructive methods, surveys, and integrated information. Less