【摘要】：在我國(guó),黃土廣泛分布于華北和西北地區(qū)等季節(jié)性凍土區(qū),隨著外界氣溫變化,該地區(qū)的黃土在每年會(huì)經(jīng)歷數(shù)次的凍融循環(huán)。在凍融循環(huán)作用下,黃土的物理力學(xué)性質(zhì)發(fā)生了改變,直接影響到工程的穩(wěn)定性及耐久性。通過前期的山西省黃土地貌地質(zhì)災(zāi)害防治的初期調(diào)查研究發(fā)現(xiàn),凍融作用也是誘發(fā)黃土地質(zhì)災(zāi)害的重要原因之一。然而,到目前為止對(duì)季節(jié)性凍土的研究并不多,且都局限在青藏甘肅等地區(qū),對(duì)華北地區(qū)尤其是山西地區(qū)更是缺少研究。因此研究?jī)鋈谘h(huán)作用對(duì)于黃土的影響具有非常重要的意義。本文主要以太原東中環(huán)路工程為背景,通過室內(nèi)模擬凍融循環(huán)試驗(yàn),分別分析不同凍融循環(huán)次數(shù)和凍結(jié)溫度對(duì)兩種土樣(路基原土和黃土填料)的抗剪強(qiáng)度的影響,并將室內(nèi)試驗(yàn)的結(jié)果用于黃土路基邊坡穩(wěn)定性分析中。本次試驗(yàn)共用到土樣30組,分別進(jìn)行在凍結(jié)溫度為-20℃、-10℃、-5℃下進(jìn)行1、3、5、9次凍融循環(huán)試驗(yàn),抗剪強(qiáng)度測(cè)定采用直剪試驗(yàn),并在直剪試驗(yàn)后測(cè)土樣含水率,邊坡穩(wěn)定性分析采用大型有限元分析軟件ABAQUS。具體結(jié)果及結(jié)論如下:1.黃土的力學(xué)性質(zhì)方面:在凍融循環(huán)后,土樣的抗剪強(qiáng)度都降低,其中其中粘聚力c減小較為明顯,內(nèi)摩擦角?變化幅度很小,在工程中可以認(rèn)為內(nèi)摩擦角?在凍融循環(huán)之后沒有變化。且在不同凍融循環(huán)的次數(shù)與凍結(jié)溫度下,土樣抗剪強(qiáng)度降低的幅度不同。具體表現(xiàn)為:凍結(jié)溫度越低,抗剪強(qiáng)度降低越多;凍融循環(huán)次數(shù)越多,抗剪強(qiáng)度降低越多,且在第一次凍融循環(huán)后抗剪強(qiáng)度降低最多,之后隨著循環(huán)次數(shù)增加,每次凍融循環(huán)后抗剪強(qiáng)度的減小值不斷變小。粘聚力c的變化規(guī)律與抗剪強(qiáng)度基本相同。凍融后濕陷性的黃土抗剪強(qiáng)度降低值大于非濕陷性黃土。2.黃土的物理性質(zhì)方面:在封閉系統(tǒng)下進(jìn)行凍融循環(huán)后,土樣的含水率基本不發(fā)生變化,即封閉系統(tǒng)下凍融循環(huán)作用對(duì)黃土的含水率沒有影響。3.路基邊坡穩(wěn)定性方面:利用強(qiáng)度折減法分析該工程中路基邊坡的穩(wěn)定性,分析得出,在凍融循環(huán)后,路基邊坡穩(wěn)定性安全系數(shù)減小。與凍融前相比,經(jīng)過凍融循環(huán)后邊坡內(nèi)塑性應(yīng)變區(qū)發(fā)展更快、塑性變形區(qū)范圍更大。
[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，

本文編號(hào)：2394677