恐龙化石在风化破坏过程中内部裂隙扩展的试验模拟研究

Experimental Simulation of Internal Fracture Expansion in Dinosaur Fossils during Weathering Destruction

在理论分析的基础上,利用试验结果模拟分析单轴压力作用下含裂隙恐龙化石断裂损伤过程。在FLAC3D中采用FISH语言编写了基于体元分析的计算程序,采用弹脆性本构模型,分析了试验过程中恐龙化石的裂纹萌生→扩展→贯通规律和裂隙化石的断裂损伤机制。在单轴压缩作用下,含有裂隙的恐龙化石试件的破坏过程主要分三个阶段:即线性变形阶段、非线性变形阶段和软化阶段,当载荷超过应变峰值强度后,化石内部将生成大量新的诱导裂隙,导致化石内部结构发生剧烈变化。值得注意的是,恐龙化石峰后的强度软化过程非常不稳定,峰值附近的材料力学行为对化石试件内部缺陷的分布十分敏感。试验表明,有裂隙恐龙化石的抗压强度值比无裂隙恐龙化石的抗压强度值小30%,最终的残余抗压强度也略小,在加载应力作用下,相比不含内部裂隙的恐龙化石,内含裂隙的恐龙化石其内部裂隙会迅速大量扩展,加重了恐龙化石的风化程度和破坏速度。

On the basis of theoretical analysis,the fracture damage process of fractured dinosaur fossils under uniaxial pressure has been simulated and analyzed.The calculation program based on volume element analysis is compiled in FLAC3D with FISH language.The crack initiation propagation penetration law and fracture damage mechanism of dinosaur fossils have been analyzed by using elastic-brittle constitutive model.Under uniaxial compression,the failure process of dinosaur fossil specimens with cracks can be divided into three stages,they are linear deformation stage,non-linear deformation stage and softening stage.When the load exceeds the peak strain strength,a large number of new induced cracks will be formed in the fossil,resulting in drastic changes in the internal structure of the fossil.It is noteworthy that the post-peak strength softening process of dinosaur fossils is very unstable,and the mechanical behavior of materials near the peak is very sensitive to the distribution of internal defects in fossil specimens.The experimental results show that the compressive strength of fractured dinosaur fossils is 30%,lower than that of non-fractured dinosaur fossils,and the ultimate residual compressive strength is also slightly smaller.Under loading stress,compared with dinosaur fossils without internal fissures,the internal fissures of fractured dinosaur fossils will expand rapidly and greatly,which aggravates the weathering degree and destruction speed of dinosaur fossils.