Wang Hao, Zong Qi, Lu Ziyi, Wang Haibo
School of Civil Engineering and Architecture, Anhui University of Science and Technology, Huainan, 232001, Anhui, China.
China Construction Sixth Bureau Eighth Construction Co., LTD, Hefei, 230041, Anhui, China.
Sci Rep. 2024 Jun 10;14(1):13338. doi: 10.1038/s41598-024-64273-4.
In order to investigate the effects of strain rate and water saturation on the energy dissipation and crack growth of tuff, uniaxial compression tests were carried out on dry and water saturated tuff with different strain rates using an electro-hydraulic servo press and a 50 mm diameter split Hopkinson pressure rod (SHPB) device. High-speed camera and Image J image analysis software were used to obtain the crack growth process of the specimen under impact load, and fractal dimension was introduced to quantitatively study the crack growth degree. The results show that more than 90% of the energy is stored in the specimen as elastic energy when it reaches the peak stress under static load. The average total energy of water-saturated specimens is 67.55% of that of dry specimens. The average energy dissipation density of water-saturated specimens under 0.3 MPa, 0.4 MPa and 0.5 MPa air pressure is 0.79, 0.91 and 0.92 times of that of dry specimens, respectively. Water-saturated specimens will deteriorate and thus reduce their energy storage and energy absorption effects. The reflected energy, transmitted energy, absorbed energy and incident energy are linear, logarithmic and linear functions, respectively, and the energy absorptivity and specific energy absorptivity of water-saturated specimens are lower than those of dry specimens. Due to the existence of "stefan" effect, the increase of energy dissipation density of water-saturated specimen at high strain rate is greater than that of dry specimen. The mean fractal dimension of water-saturated specimens under 0.3 MPa, 0.4 MPa and 0.5 MPa is 1.09, 1.05 and 1.16 times that of dry specimens. At the same strain rate, the number and width of cracks in water-saturated specimens are larger than that in dry specimens. Water-saturated behavior reduces the energy absorption capacity of tuff, increases the fractal dimension of crack growth, and significantly reduces the resistance of water-saturated rock to external loads.
为了研究应变速率和饱和度对凝灰岩能量耗散及裂纹扩展的影响，采用电液伺服压力机和直径50mm的分离式霍普金森压杆（SHPB）装置，对不同应变速率下的干燥和饱水凝灰岩进行了单轴压缩试验。利用高速摄像机和Image J图像分析软件获取冲击载荷作用下试样的裂纹扩展过程，并引入分形维数定量研究裂纹扩展程度。结果表明，在静载作用下，试样达到峰值应力时，超过90%的能量以弹性能的形式存储在试样中。饱水试样的平均总能量为干燥试样的67.55%。在0.3MPa、0.4MPa和0.5MPa气压下，饱水试样的平均能量耗散密度分别为干燥试样的0.79倍、0.91倍和0.92倍。饱水试样会发生劣化，从而降低其能量存储和能量吸收效果。反射能量、透射能量、吸收能量和入射能量分别为线性、对数和线性函数，饱水试样的能量吸收率和比能吸收率低于干燥试样。由于“斯蒂芬”效应的存在，饱水试样在高应变速率下能量耗散密度的增加幅度大于干燥试样。在0.3MPa、0.4MPa和0.5MPa气压下，饱水试样的平均分形维数分别为干燥试样的1.09倍、1.05倍和1.16倍。在相同应变速率下，饱水试样的裂纹数量和宽度均大于干燥试样。饱水状态降低了凝灰岩的能量吸收能力，增加了裂纹扩展的分形维数，并显著降低了饱水岩石对外加载荷的抵抗能力。
