冻融循环作用对黄土路基性质及边坡稳定性的影响研究
发布时间：2018-12-29 09:44
【摘要】：在我国,黄土广泛分布于华北和西北地区等季节性冻土区,随着外界气温变化,该地区的黄土在每年会经历数次的冻融循环。在冻融循环作用下,黄土的物理力学性质发生了改变,直接影响到工程的稳定性及耐久性。通过前期的山西省黄土地貌地质灾害防治的初期调查研究发现,冻融作用也是诱发黄土地质灾害的重要原因之一。然而,到目前为止对季节性冻土的研究并不多,且都局限在青藏甘肃等地区,对华北地区尤其是山西地区更是缺少研究。因此研究冻融循环作用对于黄土的影响具有非常重要的意义。本文主要以太原东中环路工程为背景,通过室内模拟冻融循环试验,分别分析不同冻融循环次数和冻结温度对两种土样(路基原土和黄土填料)的抗剪强度的影响,并将室内试验的结果用于黄土路基边坡稳定性分析中。本次试验共用到土样30组,分别进行在冻结温度为-20℃、-10℃、-5℃下进行1、3、5、9次冻融循环试验,抗剪强度测定采用直剪试验,并在直剪试验后测土样含水率,边坡稳定性分析采用大型有限元分析软件ABAQUS。具体结果及结论如下:1.黄土的力学性质方面:在冻融循环后,土样的抗剪强度都降低,其中其中粘聚力c减小较为明显,内摩擦角?变化幅度很小,在工程中可以认为内摩擦角?在冻融循环之后没有变化。且在不同冻融循环的次数与冻结温度下,土样抗剪强度降低的幅度不同。具体表现为:冻结温度越低,抗剪强度降低越多;冻融循环次数越多,抗剪强度降低越多,且在第一次冻融循环后抗剪强度降低最多,之后随着循环次数增加,每次冻融循环后抗剪强度的减小值不断变小。粘聚力c的变化规律与抗剪强度基本相同。冻融后湿陷性的黄土抗剪强度降低值大于非湿陷性黄土。2.黄土的物理性质方面:在封闭系统下进行冻融循环后,土样的含水率基本不发生变化,即封闭系统下冻融循环作用对黄土的含水率没有影响。3.路基边坡稳定性方面:利用强度折减法分析该工程中路基边坡的稳定性,分析得出,在冻融循环后,路基边坡稳定性安全系数减小。与冻融前相比,经过冻融循环后边坡内塑性应变区发展更快、塑性变形区范围更大。
[Abstract]:Loess is widely distributed in seasonal frozen soil regions such as North China and Northwest China in China. With the change of external temperature, loess in this area will undergo several freeze-thaw cycles every year. Under the action of freeze-thaw cycle, the physical and mechanical properties of loess have been changed, which directly affects the stability and durability of engineering. Through the early investigation and study on the prevention and treatment of loess geomorphologic geological hazards in Shanxi Province, it is found that freezing and thawing is also one of the important reasons for inducing loess geological disasters. However, up to now, there are few researches on seasonal permafrost, which are confined to Qinghai-Xizang, Gansu and other regions, especially in North China, especially in Shanxi. Therefore, it is very important to study the influence of freeze-thaw cycle on loess. In this paper, based on the background of Taiyuan East Central Loop Project, the effects of different freezing and thawing cycles and freezing temperatures on the shear strength of two soil samples (subgrade original soil and loess filler) are analyzed through indoor simulated freeze-thaw cycle test. The results of laboratory tests are applied to the stability analysis of loess subgrade slope. In this experiment, 30 groups of soil samples were used to carry out freezing test at -20 鈩，
本文编号：2394677
[Abstract]:Loess is widely distributed in seasonal frozen soil regions such as North China and Northwest China in China. With the change of external temperature, loess in this area will undergo several freeze-thaw cycles every year. Under the action of freeze-thaw cycle, the physical and mechanical properties of loess have been changed, which directly affects the stability and durability of engineering. Through the early investigation and study on the prevention and treatment of loess geomorphologic geological hazards in Shanxi Province, it is found that freezing and thawing is also one of the important reasons for inducing loess geological disasters. However, up to now, there are few researches on seasonal permafrost, which are confined to Qinghai-Xizang, Gansu and other regions, especially in North China, especially in Shanxi. Therefore, it is very important to study the influence of freeze-thaw cycle on loess. In this paper, based on the background of Taiyuan East Central Loop Project, the effects of different freezing and thawing cycles and freezing temperatures on the shear strength of two soil samples (subgrade original soil and loess filler) are analyzed through indoor simulated freeze-thaw cycle test. The results of laboratory tests are applied to the stability analysis of loess subgrade slope. In this experiment, 30 groups of soil samples were used to carry out freezing test at -20 鈩，
本文编号：2394677
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