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| 含冰率影响下冻结道砟集料的三点弯曲试验研究 |
| Experimental study on three-point bending test of frozen ballast aggregate under different ice contents |
| Received:April 01, 2022 Revised:May 30, 2022 |
| DOI：10.7520/1001-4888-22-082 |
| 中文关键词: 寒区铁路 冻结道砟 三点弯曲 含冰率 断裂能 |
| 英文关键词:cold region railway ice-bonded ballast three-point bending ice content fracture energy |
| 基金项目:国家自然科学基金项目(11572067, 11872136) |
| Author Name | Affiliation | | LI Xu | State Key Laboratory of Structural Analysis of Industrial Equipment, Dalian University of Technology, Dalian 116024, Liaoning, China | | YAN Ying* | School of Civil Engineering, Dalian Jiaotong University, Dalian 116028, Liaoning, China | | XUE Yizhen | State Key Laboratory of Structural Analysis of Industrial Equipment, Dalian University of Technology, Dalian 116024, Liaoning, China | | JI Shunying | State Key Laboratory of Structural Analysis of Industrial Equipment, Dalian University of Technology, Dalian 116024, Liaoning, China |
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| 中文摘要: |
| 寒区有砟轨道中碎石道床在低温冰冻条件下的力学性能与常温明显不同，道砟颗粒间的冻结强度是影响道床动力学特性的一个重要参数。为进一步探究级配碎石在冻结条件下的弯曲力学性能，设计并制备了不同含冰率的冻结碎石集料试样,通过开展室内低温三点弯曲试验，研究了含冰率对冻结试样加载力-挠度曲线及弯曲强度的影响，并分析了冻结试样的断裂行为及断裂耗能情况。试验结果表明，试样的弯曲断裂失效过程可以分为脆性断裂和峰后应变软化型断裂两部分，加载力-挠度全曲线在脆性断裂时出现明显加载力跌落现象，而在应变软化型断裂过程中曲线下降趋势平缓。含冰率的提高显著增大了试样的弯曲强度，含冰率与弯曲强度之间的关系可近似线性表示。高含冰率试样弯曲脆性断裂时试样中部下方可观察到明显的受拉裂纹，并沿着道砟接触面向上不断扩展。含冰率较低时，试样脆性断裂耗能略高于应变软化型断裂耗能，其耗能占总消耗能量的70%以上，试样以脆性断裂为主；随着含冰率增大，试样脆性断裂能占比急速下降，应变软化型断裂逐渐占主体且不容忽视。 |
| 英文摘要: |
| Compared with normal temperature environment, the mechanical properties of railway ballast bed in cold region are obviously different under freezing condition. The freezing strength between ice-bonded ballast particles is an important parameter affecting the dynamic characteristic of ballasted railway track. To further explore the bending mechanical properties of grading railway ballast under freezing condition, ice-bonded ballast aggregate specimen with different ice content were prepared and indoor three-point bending test was carried out at low-temperature environment. The effects of ice content on loading force-deflection curves and bending strength were studies. Meanwhile, fracture behaviour and the dissipated fracture energy of specimen were analyzed. The experimental results show that the failure process of bending fracture can be divided into brittle fracture and post-peak strain-softening fracture. The loading-deflection curves appear to obvious loading force drop when brittle fracture happens, after that the curve present a gentle downward trend in strain-softening fracture process. With the increasing ice content, the bending strength increases significantly, which can be expressed linearly approximately. In the process of bending fracture, an obvious tensile crack can be observed at the bottom of specimen with high ice content and expand upward along the contact face between ballast particles. When the ice content is low, the energy consumption of brittle fracture is slightly higher than that of strain-softening fracture, accounting for more than 70% of the total energy consumption. The specimen is manly brittle fracture. With the increasing the ice content, the proportion of brittle fracture energy decreases rapidly, and the strain-softening fracture is the main part of the specimen failure and cannot be ignored. |
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