龙游石窟洞室围岩长达8a的风化速度及风化时限研究

EIGHT YEARS TEST RESULTS OF WEATHERING RATES AND TIME LIMIT PREDICTION OF CHISEL IMPRINTS ON PELITIC SILTSTONE INSIDE FIVE LONGYOU CAVERNS

本文以龙游石窟围岩表面凿痕为研究对象,采用压模法,自2004年开始,每4a一次对凿痕进行了3次测量,提取了凿痕的几何特征曲线,并量化了其几何特征。通过不同时间的测量结果对比,对洞室围岩的风化速度进行了研究,并对洞室围岩凿痕的风化趋势给出了预测。研究结果表明,在2004～2012年8a内的平均风化速度0.28～0.5mm.a-1,最大风化速率为0.46～0.89mm.a-1。且后4a内的平均风化速率要小于前4a的风化速率。洞室内凿痕在目前环境条件下的风化时限为30a左右,即其可保持的时间尺度在百年范围内。换句话说,在近百年后,洞室内的精美凿痕将消失殆尽。基于此,本文提出了减缓风化的初步建议。该成果可为更好地保护龙游石窟、科学开发国家古文物、减少管理风险提供科学依据。

This paper presents a case study on the weathering rate of pelitic sihstone as the surrounding rock of Longyou underground caverns. The chisel imprints on the inner surface of the surrounding rock were measured using the mixture of plasticeue and additives in 2004, 2008 and 2012 ,respectively. The maximum height difference and fluctuation ratio are adopted as the quantitative indexes to describe the shapes of the chisel imprints. According to the measured results, the weathering rate of the surrounding rock is calculated. The average weathering rate is about 0.28 to 0.5mm.a-1. The maximum weathering rate is about 0. 46 -0. 89mm.a-l. The weathering rate value in the last 4 years is smaller than that in the former 4 years. Under the micronvironment, the weathering time limit of the 5 caverns is about 30 years, which means the chisel imprints would be vanished within 100 years. Protective measures should be carried out as fast as possible. The research results can provide scientific supports for the pro-tection of Longyou Caverns, scientific and reasonable development of national cultural relics and reduce of management risks.