潼南大佛寺摩崖造像水害治理浅析

A Primary Study on Water Hazard Control for Buddhas Carved into the Cliff of Great Buddha Temple in Tongnan County

水害一直是石窟寺保护中的一个技术难题。从潼南大佛寺摩崖造像区水文气象、地形地貌及地质结构入手,分析摩崖造像区域受到的主要水害侵蚀。地表水对摩崖造像影响主要为洪峰期洪水淹没造像,冲蚀造像区所在的斜坡坡脚,岩体底部掏蚀悬空缺失支撑,或将岩底泡软,降低岩体承重力,导致岩体形变甚至对摩崖造像造成不可逆性毁坏。大气降水冲蚀造像区岩壁,易形成冲沟,破坏岩壁整体性。渗透水浸湿造像损坏文物,流至岩底,软化岩底,使得岩体失稳。地下水使摩崖造像湿度变大,软化岩体,加速风化,裂隙渗水,造像侵湿、风化脱落,文物受损。长期的水害侵蚀,使摩崖造像遭受水产生的物理危害、化学危害和生物危害等。按照“以排为主、以堵为辅、预防结合、技术助力、持续监测、科学管理、因地制宜、综合防治”的水害防治原则,依据防治不破坏的防治理念归纳出适合潼南大佛寺摩崖造像水害的防治方法。

Water hazards have been imposing technical challenges for the conservation of temples carved into rocks. Based on the hydrology, climate, terrains, landscape, and geographical structure of the area around the buddhas carved into the cliff of Great Buddha Temple in Tongnan County, it was concluded that the area with carved buddhas was mainly subject to two types of water erosion. That is to say, surface water damages carved buddhas mainly through the following mechanisms. During the flood season, the statues are submerged in the flood water, and erosion occurs at the toe of the slope on which the statues are. This causes the base of the rock to erode away and hollow out, resulting in little support for the rock;or the rock base softens after being submerged in the flood water, reducing the load the rock can bear and leading to deformation of the rock or even irreversible damage to the carved buddhas.Rainfalls also cause erosion on the cliff around the carved buddhas where gullies are likely to appear, compromising the integrity of the rock wall. After the water seeps into and damages the statues, it flows to and softens the rock base, causing instability of the rock.While underground water increases the humidity of the carved buddhas on the cliff, softens the rock, accelerates the weathering of the rock, and results in cracks on the rock. Soaked in water, these statues deteriorate due to weathering before falling apart. Hence, the cultural heritage is damaged.The principle for water hazard prevention and control is as follows: the focus should be to drain the water, which should be supplemented with water supply blockage and water hazard prevention;continuous monitoring and scientific management should be carried out with the support of technologies;and local conditions should be fully utilized to comprehensively prevent and control water hazard. On this basis, referring to the idea that prevention and control should be carried out without any damage to the heritage, the authors analyzed the hydrological and geographical features of the area with the carved buddhas, water hazards faced by the buddhas carved into the cliff, and the current status of water hazard prevention and control. Then, methods for water hazard prevention and control at the Great Buddha Temple in Tongnan County are summarized.