石窟薄层顶板破坏的早期潜在原因分析

为了探讨导致某石窟4号硐顶板破坏的最初潜在原因，根据石窟变形破坏规律及结构边界条件，采用粘弹性薄板理论，给出了广义开尔文模型下岩层的粘弹性变形、应力解析解。为了在任意一时刻给出全域应力、位移的分布状态，提出了一种解析解全域逐点搜索法，将全域划分细密网格，用所建立的解析解计算每小区中点的应力及网格点位移值。通过分析计算，给出了石窟顶板随时间变化的位移场、变形规律及顶板可能产生受拉破坏的变化规律，其中，有两处的受拉区分界线与现在的破坏裂缝线基本吻合，说明石窟成形初期，因内能释放而产生的受拉区及其边界分界线是后来真正破坏的早期潜在不稳定源。这一结论对保护和维护石窟稳定性具有实际参考意义。实例表明，所建立的模型及分析方法是正确和合理的，方法及结论均具有通用性。

Analysis of initial latent causes for grotto roof damage

In order to research into initial latent causes of roof damage for some Grotto No.4, the viscoelastic thin plate theory is used for setting up analytical solution of viscoelastic deformation and stress for the generalized Kelvin model, based on the laws of deformation and damage and structural boundary conditions for Grotto No.4 .To obtain the stress field and the displacement field of whole region at any time, a searching method of analytical total area point by point is presented, in which total region is divided into many small zones and each zone stress and each gridpoint displacement are calculated by given analytic formulas. By calculation and analysis,the displacement field and varied deformation and tensile damage region with time are given for the grotto top plate, where two dividing lines of possible tensile damage region are almost identical with in-situ measurement. This shows the boundaries of initial tensile region are unstable source of later real damage. The conclusion is useful to protecting and maintaining the grottoes. The case analysis has shown that presented model and analytical method are correct and rational. The method and conclusion can be in common use.