兰州大学机构库 >土木工程与力学学院
冲击式冻土开挖机械斗齿结构优化研究
Alternative TitleRESEARCH ON BUCKET STRUCTURE OPTIMIZATION OF IMPACT EXCAVATOR FOR FROZEN SOIL
李蒙蒙
Subtype硕士
Thesis Advisor慕青松
2015-05-23
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword冻土力学 机械开挖 冻土切削 冻土破碎 振动与冲击
Abstract我国冻土分布广泛,随着寒区工程建设日益频繁,冻土开挖问题更加普遍,然而,由于冻土强度为融土的10~20倍,导致冻土开挖困难,是目前困扰寒区工程作业的一项技术难题。因此有必要深入开展冻土的破碎方法的研究,从而改善冻土开挖技术。 本文首先回顾了冻土开挖相关方面的研究现状与进展,并对SHPB试验技术、有限元理论和数值模拟方法做了简要阐述。根据已有文献的实验与数值模拟相结合,获取了适用于冻土的HJC动态损伤模型参数,基于此模型,采用ANSYS/LS-DYNA大型有限元显式动力分析软件,对冻土在高速冲击下的损伤破碎过程进行了数值模拟,得出以下几点结论: (1)通过模拟冻土SHPB试验,发现数值模拟与试验结果符合的比较好,应力-应变曲线变化趋势一致。所以利用大型有限元软件对冻土进行冲击模拟是可行的,并基于此模拟,获取了冻土HJC模型参数。 (2)基于上述模型参数模拟了楔形刀具正冲冻土的过程,发现在相同的冲击速度下,楔形冲头较平角冲头更易破碎冻土,冲头越尖锐,越容易贯入冻土中。但并不是楔形角越小,破碎冻土的效果越好,而是存在一最佳楔形角,约为45o<上标!>,因此在冲击式开挖破碎冻土中,机械冲头的楔形角设计在45o<上标!>左右较为合理。 (3)用45o<上标!>的楔形冲头以不同入射角对冻土展开冲击模拟,结果显示,在冲击过程中,刀具有被土体弹回的现象发生,弹回现象越明显,用于破坏冻土的动能越少,额外耗能越多,不利于冻土破碎。当以30o<上标!>或60o<上标!>入射时,土体损伤量最大,当以45o<上标!>入射时,冻土损伤量最小。因此在冲击破碎冻土时,入射角应选为30o<上标!>或60o<上标!>左右,这样冲击破碎冻土所需能耗较小,效果较好。
Other AbstractChina has the wide distribution area of frozen soil. As constructions are increasingly frequent in cold regions consequently, the problem of frozen soil excavation is more widespread. However, the strength of frozen soil much stronger than unfrozen soil that the difficulty of frozen soil excavation is increased, which has been the technical problem that persecuted engineering operations in cold regions. It is necessary to carrying out the research on crushing characteristics、excavation method and excavation equipment optimization of frozen soil, thus improving the frozen soil excavation technology. This article reviews the research status and progress of frozen soil excavation and gives a general introduction to the SHPB test technology, the finite element theory and numerical simulation method. Moreover,by combining the experiment ,which in the existing references ,with numerical simulation, Getting the parameters of the constitutive model H-J-C that Suitable for frozen soils. Then based on this model, and using the finite element dynamic analysis software to simulate the damage process of frozen soils under high speed impact. We obtain the following conclusions: (1)Through simulating the SHPB test of permafrost, it is found that results of numerical simulation were better conformed to experimental results, especially the trends of stress-strain curves, so it is feasible to use large-scale finite element software to simulate the impact test of frozen soils. And by this simulation, we obtained the parameters of permafrost H-J-C model. (2) Based on the above model parameters, we simulate the process of wedge tools vertical impact frozen soils. Under the same velocity, wedge cutters are more easily broken permafrost than cubic cutters, the sharper cutter is, the more easily it penetrates into permafrost. But not the wedge angle is smaller, the effect is better. There is a best wedge angle of about 45o <上标!>to break permafrost. So the wedge angle of mechanical excavator’s punch designed about 45o<上标!> is more reasonable when breaking permafrost. (3) Simulating wedge punch of 45o<上标!> impact permafrost with different incident Angles, the results showed that cutters had been rebound by soils. The rebound phenomenon is more obvious, the less kinetic energy be used to destroy permafrost, the more additional energy consumed, and it is unfavorable to break permafrost. When incident angle is about 30o<上标!> or 60o<上标!>...
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/226644
Collection土木工程与力学学院
Recommended Citation
GB/T 7714
李蒙蒙. 冲击式冻土开挖机械斗齿结构优化研究[D]. 兰州. 兰州大学,2015.
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