Experimental Research on Dynamic Characteristics of Porous Basalt in Freezing-Thawing Conditions
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摘要: 在路基边坡工程中格构式骨架护坡形式最为多见,但在我国北部地区由于昼夜温差大,致使其边坡支护能力减弱。为研究霍普金森玄武岩力学性能受冻融循环的影响,对边坡岩石冻融后的玄武岩进行冲击压缩试验,选用冻融次数、不同养护状态和不同动态冲击速度为工况进行分析讨论,确保在冲击荷载作用下寒区边坡具有良好的抗压性能,使用φ50的分离式霍普金森装置探究岩样冻融循环动态强度的影响规律。试验结果表明:随冲击速度的增大,各岩样的动态抗压强度呈线性增长趋势;在同一应变率和相同冻融次数条件下,冻结养护环境对岩样承载性有增强作用,饱水养护环境对岩样承载性有软化作用,且冻结环境下动态抗压的峰值强度最大,饱水状态强度最小,两种强度因子随冻融次数的增加逐渐趋近于1;岩样动态强度的应变率变化受冻融循环的弱化作用在前期最为显著;随冻融次数的增加,饱水岩样的应变逐步增大,峰值应力逐步降低;冻融后期阶段,岩样的强度变化和应变率效应均在逐渐减弱。Abstract: In subgrade slope engineering, latticed skeleton slope protection is the most common, but the temperature difference between day and night is large in northern China, resulting in the weakening of slope supporting capacity. In order to study the impact compression test of the basalt after freezing and thawing of the slope rock, the number of freeze-thaw cycles, different curing states and different dynamic impact velocities were selected as typical working conditions to analyze and discuss the influence of the mechanical properties of Hopkinson basalt on the freeze-thaw cycle, and to ensure that the slope in the cold region has good compressive performance under impact loading, the influence of 50 mm diameter separated Hopkinson pressure rod on the dynamic strength of the freeze-thaw cycles was analyzed. The experimental results showed that with the increase of impact velocity, the dynamic compressive strength of each rock sample showed a linear growth trend. Under the same strain rate and the same number of freeze-thaw cycles, the freezing curing environment had an enhanced effect on the bearing capacity of rock samples, and the saturated conservation environment had a softening effect on the bearing capacity of rock samples, and the peak strength of dynamic compressive resistance in freezing environment was the largest, and the strength of saturated state was the smallest, and the two intensity factors gradually approached 1 with the increase of freeze-thaw cycles. The change of strain rate of the dynamic strength of rock samples was most significant in the early stage due to the weakening effect of freeze-thaw cycles. With the increase number of freeze-thaw cycles, the strain of saturated specimens gradually increased, and the peak stress gradually decreased. In the late stage of freezing and thawing, the strength change and strain rate effect of rock samples were gradually weakening.
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Key words:
- basalt /
- impact velocity /
- freezing-thawing damage /
- Hopkinson /
- dynamic compressive intensity
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