Shao Dongqiao, Zhang Wenlun, You Zhiming
The Third Geological and Mineral Exploration Institute of Gansu Provincial Bureau of Geology and Mineral Resources, Lanzhou, 730050, China.
Gansu Geological Disaster Prevention and Control Engineering Exploration and Design Institute Co. Ltd., Lanzhou, 730050, Gansu, China.
Heliyon. 2024 Jul 25;10(15):e35163. doi: 10.1016/j.heliyon.2024.e35163. eCollection 2024 Aug 15.
Numerous manually excavated loess caves are present within a cultural relic protection zone in the northwestern region of China. The collapse of these caves frequently leads to the cracking, tilting, and even collapse of ancient buildings above, posing a severe threat to the safety of cultural architectural relics. Investigating the stability and characteristics of deformation and failure in loess caves is essential for effectively reinforcing and protecting cultural relics. A two-dimensional model of a loess underground cavern was developed using OptumG2. The stability and modes of deformation and failure in the underground cavern were analyzed through the augmentation of soil gravity and the strength reduction method. This analysis determined the cavern's safety factor, force, deformation and damage mode, and the plastic zone's progression. Numerical simulations analyzed the force characteristics of the support structure under different stress release ratios. The findings revealed that, with the implementation of an anchor rod concrete lining support scheme, the most probable failure mode is a shear failure, initiating at the arch foot. The ground's stress release rate does not influence the safety factor of the cavern but rather the material, design, and strength of the support structure. However, the magnitude of the internal forces acting on the supporting structure by the soil in the cavern is related to the degree of ground stress release. When applied during significant stress release, support structures may experience reduced internal forces, albeit with more substantial stratum displacement; opting for an appropriate stress release when applying support structures is crucial for achieving optimal stratum displacement and lining internal forces.
在中国西北地区的一个文物保护区内存在大量人工挖掘的黄土洞穴。这些洞穴的坍塌经常导致上方古建筑出现裂缝、倾斜甚至坍塌，对文化建筑文物的安全构成严重威胁。研究黄土洞穴的稳定性以及变形破坏特征对于有效加固和保护文物至关重要。利用OptumG2建立了黄土地下洞室的二维模型。通过增加土体自重和强度折减法分析了地下洞室的稳定性以及变形破坏模式。该分析确定了洞室的安全系数、受力、变形和破坏模式以及塑性区的发展情况。数值模拟分析了不同应力释放率下支护结构的受力特性。研究结果表明，采用锚杆混凝土衬砌支护方案时，最可能的破坏模式是剪切破坏，始于拱脚处。地面应力释放率不影响洞室的安全系数，而是影响支护结构的材料、设计和强度。然而，洞室内土体作用在支护结构上的内力大小与地面应力释放程度有关。在应力大幅释放时施加支护结构，支护结构的内力可能会减小，尽管地层位移会更大；在施加支护结构时选择合适的应力释放对于实现最佳地层位移和衬砌内力至关重要。
