Wang Hanqiu, Liu Chengyong, Wu Yuyi, Guan Yuhua, Zhao Tongde
China Coal Energy Research Institute Co., Ltd, Xi'an, Shanxi, PR China.
Shandong Huaxin Construction Engineering Group Co., Ltd., Taian, Shandong, PR China.
PLoS One. 2025 Jul 29;20(7):e0327902. doi: 10.1371/journal.pone.0327902. eCollection 2025.
Shotcrete, as a highly efficient reinforcement material widely used in geotechnical engineering, demonstrates irreplaceable advantages in projects such as tunnel excavation, mine roadway support, and slope protection. However, when shotcrete becomes tightly bonded with rock masses, the energy evolution and crack initiation mechanisms between the two materials exhibit remarkable complexity. Different loading rates significantly alter the internal stress distribution and deformation characteristics within the composite system, thereby influencing the patterns of energy evolution and crack propagation. Consequently, it is essential to investigate the mechanical behavior of filling mortar-rock under varying loading rates. Firstly, uniaxial tests with four loading rates were conducted for the composite specimens, and the effects of loading rate on the mechanical parameters, energy evolution and fracture modes were analyzed. The results show that the mechanical parameters of the composite decrease with the rise of loading rate, and the decrease reaches the maximum when the mortar strength is M20. All three types of energies decreased exponentially with increasing loading rate. The decrease reaches the maximum at a mortar strength of M40. Subsequently, a damage model applicable to the composite specimens was established based on the development rules of the dissipated energy and the compaction coefficient. Finally, PFC2D was used to simulate and analyze the specimens with mortar grade of M30 to investigate the crack propagation and stress evolution process at four loading rates. The results show that tensile stress is the causative factor of crack propagation. The cracks first appeared at the interface, and were mainly distributed on both sides of the specimen after cracking.
喷射混凝土作为一种广泛应用于岩土工程的高效加固材料，在隧道开挖、矿山巷道支护和边坡防护等工程中具有不可替代的优势。然而，当喷射混凝土与岩体紧密结合时，两种材料之间的能量演化和裂纹萌生机制表现出显著的复杂性。不同的加载速率会显著改变复合体系内部的应力分布和变形特性，从而影响能量演化和裂纹扩展的模式。因此，研究不同加载速率下充填砂浆 - 岩石的力学行为至关重要。首先，对复合试件进行了四种加载速率的单轴试验，并分析了加载速率对力学参数、能量演化和断裂模式的影响。结果表明，复合材料的力学参数随加载速率的升高而降低，当砂浆强度为M20时，降低幅度最大。三种能量均随加载速率的增加呈指数下降。在砂浆强度为M40时，下降幅度最大。随后，根据耗散能量和压实系数的发展规律，建立了适用于复合试件的损伤模型。最后，利用PFC2D对砂浆等级为M30的试件进行模拟分析，研究了四种加载速率下的裂纹扩展和应力演化过程。结果表明，拉应力是裂纹扩展的成因。裂纹首先出现在界面处，开裂后主要分布在试件两侧。
