大足石刻北山168窟围岩病害高频瑞雷波成像

High-frequency Rayleigh Wave Imaging of Diseases in Surrounding Rock Mass of Beishan Cave 168 of Dazu Rock Carvings

大足石刻北山168窟为五百罗汉窟,开凿于1119年至1125年,窟高3.3 m,宽3.14 m,进深7.1 m,是大足石刻中尺寸较大的一个重要洞窟。目前,168窟围岩裂隙风化病害十分严重,面临失稳坍塌的危险。为制定针对性的长久保护措施,需查明168窟围岩病害的现状。通过现场调查、物探、钻探等技术手段,获取了大足石刻北山168窟及邻近区域的工程地质条件。进一步,采用高频瑞雷波探测技术对168窟顶板岩体进行瑞雷波相速度成像,考虑168窟顶板岩体特定的围岩边界条件和场地工程地质条件,对洞窟顶板岩体瑞雷波相速度-深度成像剖面中的低速区分布进行成因分析和解译,揭示石窟顶板岩体风化现状和节理裂隙的发育情况。为分析评价洞窟围岩稳定性和石窟保护工程设计提供基础性地质资料和必要的计算参数,也为相关技术在文物保护工程的应用提供经验和借鉴。

The Beishan Cave 168 of Dazu Rock Carvings is a five-hundred Arhat Grotto, excavated between 1119 and 1125. The cave is 3.3 m high, 3.14 m wide and 7.1 m deep. It is an important cave with a larger size among the Dazu Rock Carvings. At present, the weathering disease and fissures in the surrounding rock mass of Cave 168 are very serious, and are in danger of collapse. In order to formulate targeted long-term protection measures, it is necessary to find out the current situation of the disease in the surrounding rock mass of Cave 168. Through on-site investigation, geophysical prospecting, drilling and other technical means, the engineering geological conditions of Beishan Cave 168 and its adjacent areas have been obtained. Furthermore, in order to reveal the weathering status of the rock mass on the top of the cave and the development of joint fissures in the rock mass, Rayleigh wave phase velocity imaging on the roof rock mass of Cave 168 is performed with high-frequency Rayleigh wave detection technology. In consideration of the specific surrounding rock boundary conditions and site engineering geological conditions of the rock mass on the roof of Cave 168, the origin analysis and interpretation of the distribution of the low-velocity zone in the Rayleigh wave phase velocity-depth imaging profile of the cave roof rock mass were developed. The results out of the work mentioned above may provide basic geological data and necessary calculation parameters for the analysis and evaluation of cave surrounding rock mass stability and stone carve protection engineering design, and also provide experience and reference for the application of related technologies in cultural relics protection projects.