砂岩石窟窟顶浅层剥落病害治理微型锚杆技术研究

The art of grottoes of china is very rich in content and form, which has great artistic, historical and scientific value, in which sandstone account for 80%. Most of the grottoes have been suffered a certain extent damage even collapse due to natural forces and human activities during more than 2000 years long history. Falling of the dangerous rock mass and the flake peeling are one of the main roof diseases of grottoes. After years of study and practice, traditional rock anchor (anchor rope) techniques have been successfully applied to reinforce the dangerous rock mass on the roof of the grottoes, the design theory and practice tend to be mature. Yet, for the flake peeling disease on the roof of grottoes, which has the characters of shallow in depth, extensive in area, small in bulk, rich in culture information, the traditional anchor technique with the characteristics of large borehole and deep anchorage is obviously not suitable. Therefore, based on the micro-soil nailing techniques developed by the applicant for curing the surface disease of earthen sites, the micro-anchor bolt technique is going to be developed for curing the flake peeling disease on the roof of sandystone grottoes in the study. The main contents of the research project consist of: develop the micro-anchor bolt technique, investigate the factors affecting the anchorage force on the micro-anchor bolt, study on the strengthening mechanism of the flake peeling disease of the roof of grottoes reinforced by the micro-anchor bolt. It is expected that the micro-anchor bolt technique has prospective application for curing flake peeling on the surface of grottoes, restoring the stone carvings and statues et. al.

中国石窟艺术内容和形式十分丰富，具有极高的艺术、历史和科学价值，其中砂岩型石窟约占总数的80%。在2000多年的漫长岁月中，由于自然营力和人类活动的影响，使得绝大多数石窟艺术遭受了不同程度的病害乃至破坏。危岩体塌落、片（块）状剥落是石窟窟顶岩体的主要病害之一。传统锚杆（索）技术在加固石窟窟顶大体量危岩体塌落病害方面，设计计算理论及应用已趋成熟。由于砂岩石窟窟顶剥落病害具有层间裂隙发育、层浅、面广、体量小、文化信息量大的特点，传统锚杆技术大孔径、深层锚固的特点显然不适合窟顶浅层剥落病害的治理。申请人在土遗址表层病害治理研究的基础上，拟开发研究微型锚杆技术治理砂岩石窟窟顶剥落病害。主要研究内容包括：微型锚杆技术工艺开发，微型锚杆锚固力影响因素研究，石窟窟顶剥落病害微型锚杆加固机理研究等。可以预期，微型锚杆技术在石窟窟顶窟壁剥落、石雕塑像修复等石质遗址浅层病害治理方面具有良好的应用前景。

窟顶浅层剥落、掉块病害是砂岩石窟普遍存在的主要病害形式之一，对石窟的价值、安全展示构成威胁，目前主要根据经验采用粘帖、小锚杆处理，对其加固机理、加固依据研究成果甚少。本课题针对砂岩石窟窟顶浅层剥落病害，试验开发微型加固治理技术。在调研收集国内砂岩石窟岩体物理力学性质的基础上，在室内采用标准砂、粉质黏土、水泥和水经过配合比试验，确定了能够代表现场岩体的室内模拟石窟岩体配合比；通过试验研究配制了适合于微型钻孔中灌浆锚固的粉煤灰-环氧树脂混合浆液配合比及微型封口注浆装置；采用室内模拟岩体试块和灌浆材料，选用微型钢锚杆和微型木锚杆为芯材，通过系列室内拉拔试验研究了微型钻孔直径、微型锚杆直径、长度、表面形态等因素对微型锚杆抗拔力、破坏模式的影响；试验结果表明微型钻孔中钻孔直径和微型锚杆直径之间的具有一定关系；采用数值模拟手段对微型锚杆抗拔机理及锚固效果进行了仿真分析。研究成果对砂岩石窟窟顶浅层剥落掉块病害微型锚杆加固提供了设计依据和实践数据。可以预期，微型锚杆技术在砂岩石窟窟顶窟壁剥落、石雕塑像修复、摩崖石刻剥落掉块等石质遗址浅层病害治理方面具有良好的应用前景。