A synthetic approach to weathering degree classification of stone relics case study of the Yungang Grottoes

Abstract

Classification of the weathering degree of large outdoor stone relics has long been a challenge in their protection engineering. An approach to classifying the weathering levels of the Yungang Grottoes is presented in this paper. This approach is based on combined terahertz (THz) spectra and ultrasonic velocity and the use of a least squares support vector machine (LS-SVM). A regression model for prediction of the weathering level was established using the optimal values of parameters determined by the double cross-validation (D-CV) method. This SVM regression prediction model (SVMRPM) predicts the weathering levels of the grottoes with relative errors of 8.16% or less. The SVMRPM can also be used to predict the weathering levels of some areas where ultrasonic testing is extremely difficult; the THz spectra can easily be obtained using approximately 0.2 g of sample material. This method is a highly efficient and economical technique for determining the degree of weathering of large exposed stone relics.

The Adverse Effects of TiO2 Photocatalycity on Paraloid B72 Hybrid Stone Relics Protective Coating Aging Behaviors under UV Irradiation

“…in Shanxi over the past decades. Especially, the organic compounds which are emitted from the coal burning and utilization leading to more apparent damage to the stone relics [ 11 , 12 , 13 , 14 , 15 ]. The protection of the stone heritage relics becomes increasingly urgent.…”

Ultrasonic Properties of a Stone Architectural Heritage and Weathering Evaluations Based on Provenance Site

“…Because this evaluation is a highly reliable method of non-destructive testing, several countries use it as the geological standard. Many researchers quantitatively categorize weathering grades into three to five stages according to various types of rocks, such as natural stone [41], acidic volcanic rock [37], limestone [42], andesite [36], marble [43], and granite [44] (Table 2). Among these, the durability of the natural stone does not only depend on the alteration factors, and it also depends on the mineralogy, the rock fabric, and the pore system [45].…”

“…Furthermore, different types of rock exhibit different physical properties; even identical types of rock may exhibit different absolute strengths depending on its origin. Therefore, the weathering grade standards that consider the type of rock and the conservation condition of a target heritage should be established to evaluate the weathering of a stone architectural heritage based on ultrasonic measurements [32][33][34][35][36][37].…”

Visualizing water seepage dynamics in grotto relics via atom-based representative model

“…As a global tangible cultural heritage, Yungang Grottoes and Dazu Rock Carvings have been inscribed into the World Heritage List by the United Nations Educational, Scientific and Cultural Organization (UNESCO) [1][2][3]. However, in the past few decades, the Grotto cultural relics have experienced different degrees of damage due to the longterm adverse effects of natural forces, human influences and environmental erosion, among which water seepage and weathering were responsible for the terrible deterioration and greatly threaten to the conservation of grotto relics in China [4][5][6]. Affected by complex geological structures and hydrological conditions, they have been a serious challenge.…”