Xiuwei Guo

Pores, as one of the channels for water, air, and microorganisms to enter the rock, accelerate the rock weathering process and change the physical and mechanical properties of the rock. Therefore, the study of the microscopic pore structure is of great significance for stone cultural heritage. This paper proposes a multi-scale pore structure characterization method based on backscattered scanning electron microscope (BSE) images, integrating feature engineering and machine learning techniques. First, for each pixel, 16 features are generated to construct a feature engineering. Then, these features are input into four commonly used machine learning models (Random Forest, Support Vector Machine, Multi-Layer Perceptron, Gradient Boosting Decision Tree) to distinguish pore and mineral matrix. To verify the effectiveness of the multi-channel feature input method, we compared the confusion matrix parameters (accuracy, precision, recall, and F1-score) of the four models before and after adding the feature engineering, and found that the indicators of all models increased by 1%–15%. In addition, the study also found that the Random Forest model performed the best. It can effectively segment the pores in different new images, thus could be directly applied to weathered sandstone images, providing data support for the scientific protection of stone cultural heritages.

Characterising and sourcing natural stones are essential for not only understanding the historical information carried by heritage buildings and cultural heritage sites, but also providing necessary data for restoration and conservations. Petrographic analyses by polarised microscopy, along with the integrated chemical data acquired by inductively coupled plasma-mass spectrometry (ICP-MS) and X-ray diffraction (XRD) analysis, allowed us to ascertain the compositions of stone materials. In this paper it is applied on samples collected from quarries of “three famous stones (Meiyuanshi-, Xiaoxishi-, and Dayinshi-stone)” in Ningbo and from the Sumeru platform in the main hall of Baoguosi Temple (Ningbo, Zhejiang, China). Comparison of petrographic features, major and trace elements of the stones studied indicated that they are all tuffs but of different characteristics and origin. Moreover, we were able to confirm that the Sumeru platform in Baoguosi is made of Meiyuanshi-stone. The results have demonstrated the suitability of the approach and present a practicable solution for other stone buildings.

The Yungang Grottoes, with over 1500 years of history, have been subjected to air pollution since the last century. Field investigations have indicated that acid gases, particularly sulfur dioxide (SO₂), have accumulated on the surface of the sculptures and caused various types of decay that reduce their artistic value. To shed new light on the gas–stone interaction process, artificially accelerated weathering was performed on local sandstone in the laboratory. In a specially developed test device, fresh specimens were exposed to gaseous SO₂ under different relative humidity and temperature conditions. The physical, mineralogical, and chemical changes of Yungang sandstone were evaluated conjointly using destructive and non-destructive methods. The results show that after weathering, the luminosity of all specimens changed, with a slight alteration in hue toward yellow. The weight increased to various degrees during the aging cycles, which depended on both the accumulation of matter and the detachment of particles. Higher relative humidity and cyclic temperature fluctuations favored the dissolution of carbonates and the hydrolysis of feldspar in sandstone. The concentration of ions, especially dissolved Ca²⁺ and SO₄²⁻, increased considerably over time in the near-surface region of the specimens. A trace of newly formed gypsum was detected in some specimens at the end of the test. Knowing the synergistic impact of different climatic variables will make it possible to identify the mechanisms of the deterioration of sandstone in complex environments.

In this paper, the mechanical model of grotto–eave system with cable inerter viscous damper (CIVD) is established, and the vibration control equations are established. Firstly, the stochastic response is carried out, and the optimization design of design parameters of CIVD is carried out for the grotto–eave systems with different connection types. Finally, the vibration mitigation control performance of CIVD under different seismic inputs is analyzed. The research shows that in the optimal design of CIVD, the inerter–mass ratio and damping ratio should be reduced as much as possible to improve the feasibility of the application of CIVD in cultural relics protection engineering under the condition of meeting the target damping ratio. The demand-based optimal method can minimize the cost by enhancing damping element deformation in a small damping ratio, while ensuring that the value of displacement index of grotto–eave system can be reached. Hence, the deformation and damping force of CIVD will increase simultaneously due to the efficient tuning and damping amplification of CIVD. CIVD can enlarge the apparent mass through rotation and damping force through enhancement deformation. Hence, compared with other conventional dampers (such as viscous damper), optimal CIVD has lower damping ratio under the same demand index of grotto–eave system. It can be realized that the lightweight and high efficiency of the damper, and can be applied to the vibration mitigation and reinforcement of the grotto–eave system.

In this paper, parameter analyses of a tuned inerter damper (TID) are carried out based on the displacement mitigation ratio. The optimal design of TID based on the closed-form solution method is carried out and compared with the fixed-point method. Meanwhile, applicable conditions of two methods are discussed in wider range of values of objective function under different inherent damping ratios. Finally, seismic responses of SDOF system with TID are carried out, which verifies the feasibility of the closed-form solution optimization method. Compared with the fixed-point method, the inherent damping ratio of the original structure is considered in the closed-form solution method, and the optimal damping ratio of a TID is smaller than that of the fixed-point method under same displacement mitigation ratio. The parameters’ combination of a TID designed by the fixed-point method obtains a vibration mitigation effect with a larger damping ratio by cooperating with the deformation enhancement effect of the inerter, which may make the vibration mitigation effect of the TID lower than that of the VD in structures with large inherent damping ratios. However, the deformation enhancement effect on the damping element of the inerter can be fully used by using the closed-form solution method. Better applicability and robustness are shown in closed-form solution method. Under the same displacement mitigation ratio, the damping ratio of a TID obtained by using the closed-form solution method is about one tenth of that obtained by using the fixed-point method, which can realize the lightweight design of the TID.