渗水是大足石刻保护过程中一直需要面对的首要问题,但几十年来的治理工作效果难以满足保护需求。本次研究以常规的水文地质学理论为基础,有针对性地开展石窟摩崖水文地质特征研究,基本查清了大佛湾卸荷崖壁的水文地质条件。研究表明：在大足石刻摩崖区,无论是砂岩还是泥岩,在渗流路径中,均可视为相对隔水层;石窟卸荷带主要的渗流通道是层面及卸荷影响的构造裂隙,部分张开性垂直裂隙可能为阶地形成过程中,山体伴生的地层滑动形成;大足石刻宝顶山地层展布总体为水平方向,但四川期和华北期构造运动形成的东西迹向和南北迹向宽缓褶皱,对于非饱和卸荷带渗流影响非常重大;从石窟区的水质特征可以看出,这种特殊的石窟摩崖环境下,远程渗流和近程渗流共存,地质作用和人为效应交织,构成了复杂的渗流体系,同时间接控制衍生的溶蚀、盐析等病害的发育;根据崖壁垂直卸荷效应,可以将石窟后方山体按崖壁高度进行分区,大于2倍崖壁高度为非卸荷区,1~2倍高度为卸荷影响区,1倍高度范围以内为强烈卸荷区;非卸荷区,以覆盖层、风化破碎层饱和孔隙流为主,而强烈卸荷区以非饱和、多层裂隙流为主;控制性的渗水裂隙既可以加剧局部渗水,也可以减弱周边渗水,需辩证认识张性裂隙的作用;宝顶山摩崖渗流体系存在相互跨越、越流补给等现象,形成具体的、复杂的动态渗流体。通过本次研究,为系统性,最低限度干预的大佛湾渗水治理提供理论依据,也为构建石窟崖壁这种特殊的地形、地貌和地物环境下的微水文地质条件模型提供了范例。

Water leakage has been the primary problem for the protection of Dazu Rock Carvings (DRC) along with its whole lifetime, but the effect of leakage treatment was far inferior to the demand of protection in the past few decades. Based on conventional hydrogeological theories, this study has carried out by focusing on the Grottoes Cliff Hydrogeology and the special hydrogeological conditions of the unloading cliffs in the Dafowan have been clarified basically. The research shows: Both the sandstone and mudstone of the Dafowan cliff can be regarded as relatively impermeable materials in seepage flow. The bedding planes and tectonic fractures affected by unloading forces constitute the main seepage flow channels within the DRC cliff zone. Some fractures with ten centimeters aperture may form by horizontal landsides along the strata except unloading force. The strata formation of Baodingshan is nearly horizontal, but the EW and SN trending wide-flat folds by tectonic movements of Sichuan and North China periods are very important for the seepage of unloading and unsaturated cliff zones. Water sample analysis from the research area reveals: A complex flow system with long-range and short-range seepage are coexisting within the same space. Geological rock-water interaction and human effects combine along the flow path in the particular cultural cliff rockmass. The flow and material inside water indirectly control derived diseases such as dissolution and salt precipitation. Based on the water level distribution analysis, the hill behind the carving cliff affected by unloading force can be divided into three zones. The non-unloading effect zone is greater than 2 times height of the cliff. The unloading influence zone is 1-2 times the height, and the strong unloading zone is within 1 time the height range. The non-unloading effect zone is dominated by pore saturated flow in the loose soil layer and weathered fractured layer, while the strong unloading zone is dominated by unsaturated and multi-layered fissure flows. The role of opening fractures with high penetration ability must be contemplated dialectically, the leakage water diseases can be aggregated inside these fractures and the seepage flow will be alleviated around these fractures at the same time. The main underground stream flow systems, with complicated mutual crossing flow and leakage recharge inside different flow, have been analyzed. Through this study, a theoretical basis is provided for the systematic and minimal intervention of water seepage treatment in Dafowan, and an example is provided for constructing micro hydrogeological condition models under the special terrain, landform, and environment of cliffs with cultural grottoes and carvings.