基于双边滤波石质文物逆向建模及其稳定性分析

Refinement modeling and stability analysis of stone cultural relics based on bilateral filtering

石质文物的长期稳定性问题是文物保护工作中的重点。以大足石刻卧佛前的目犍连菩萨像为研究对象,基于双边滤波算法,将三维激光扫描仪获取的点云数据导入PCL平台,实现文物表面噪声点的去除,建立包含裂隙结构面在内的菩萨像三维精细化实体模型。基于强度折减原理采用有限差分软件FLAC3D,对菩萨像现存状态展开稳定性分析,结果表明:1)双边滤波法去噪后的菩萨像模型平均偏差为-5.0~4.0 mm,标准值为1.1 mm,在去除噪声的同时完整保留了文物表面特征;2)重力荷载下,菩萨像颈部受压,项部受拉;头部裂隙的出现导致内部应力发生重分布,峰值拉应力由项部移动至裂隙端;3)菩萨像头部位移变化与折减系数呈正相关,当折减系数为1.28时,头部位移敏感度急剧增大,向临空面倾倒;4)菩萨像破坏面沿裂隙端、颈部向内部延伸,塑性区体积、最大剪应变增量逐步增大,在两区域形成抛物线贯通破坏面。该研究方法为小型、具有复杂几何特征的石质文物稳定性分析提供思路。

The long-term stability of stone cultural relics is a key concern in their preservation.This study focuses on the Bodhisattva statue in front of the reclining Buddha carved on Dazu Rock Carvings.Using bilateral filtering algorithm,the point cloud data from a 3D laser scanner were processed in the PCL platform to remove noise,preserving the surface details of the cultural relics.A refined 3D model of the Bodhisattva statue,including its fissure structure,was established.The statue’s stability was analyzed using the strength reduction method with FLAC3D software.The findings include:1)The denoising method resultes in an average deviation of-5.0 mm to 4.0 mm and a standard value of 1.1 mm,which completely retained the artifact’s surface characteristics.2)Under gravity load,the statue’s neck compressed while the top stretched,with cracks in the head redistributing internal stress,and the peak tensile stress moving from the top to the crack end.3)The statue’s head displacement correlates positively with the reduction coefficient,sharply increasing at 1.28,indicating a tendency to tip.4)The failure surface extends along the crack and neck into the relic’s interior,with the plastic zone and maximum shear strain increment forming a parabola through the two regions.This method offers insights for analyzing the stability of small stone artifacts with complex geometries.