【摘要】：黃土是一種第四紀沉積物,具有大孔隙、欠壓密性以及濕陷性,在我國有著廣泛的分布。隨著我國工程建設的不斷深入,黃土的工程問題也顯現(xiàn)了出來。其中由于季節(jié)的交替,黃上在干濕循環(huán)作用下造成的破壞是工程中遇到的主要問題,會造成邊坡、路基等的失穩(wěn)破壞。因此研究干濕循環(huán)后黃土的強度和結構性的變化顯得尤為重要。本文對干濕循環(huán)作用后的黃土進行直剪試驗,研究干濕循環(huán)次數(shù)和干濕循環(huán)幅度對黃土抗剪強度和結構強度的影響。研究結果表明,經過干濕循環(huán)后的黃土試樣抗剪強度降低。干濕循環(huán)作用主要造成黃土粘聚力的降低,而對內摩擦角幾乎沒有影響。干濕循環(huán)幅度越大、次數(shù)越多,黃土抗剪強度降低的越快、越多,在第一次干濕循環(huán)之后粘聚力降低最多。重塑土比原狀土表現(xiàn)的更為明顯。黃土的結構強度隨著干濕循環(huán)次數(shù)的增加逐漸減小,干濕循環(huán)幅度越大,對黃土的結構強度的削弱就越明顯。對干濕循環(huán)作用后的黃土進行三軸試驗,研究試驗含水率、固結圍壓、干濕循環(huán)次數(shù)和幅度對黃土結構性的影響。研究結果表明隨著試驗含水率、固結圍壓、干濕循環(huán)次數(shù)和幅度的增大,黃土結構性降低并最終趨于穩(wěn)定。采用GeoStudio軟件中的SLOPE/W模塊對不同坡度,不同干濕循環(huán)次數(shù)后的邊坡進行穩(wěn)定性分析,研究干濕循環(huán)作用對邊坡穩(wěn)定性的影響。研究發(fā)現(xiàn)隨著干濕循環(huán)次數(shù)的增加,邊坡安全系數(shù)不斷降低,且邊坡坡度不宜超過50°。
[Abstract]:Loess is a Quaternary sediment with macropores, undercompaction and collapsibility. It is widely distributed in China. With the development of engineering construction in our country, the engineering problems of loess also appear. Due to the alternation of seasons, the damage caused by dry-wet cycle is the main problem in the project, which will cause the instability of slope and roadbed. Therefore, it is very important to study the change of loess strength and structure after dry-wet cycle. In this paper, the direct shear tests of loess after dry-wet cycle are carried out to study the effects of the number of dry-wet cycles and the amplitude of dry-wet cycles on the shear strength and structural strength of loess. The results show that the shear strength of loess samples after dry-wet cycle decreases. Dry-wet circulation mainly results in the decrease of the cohesion of loess, while the internal friction angle has little effect. The larger the range of dry and wet cycles, the more times, the faster the shear strength of loess decreases, and the more the cohesive force decreases after the first dry-wet cycle. The remolded soil is more obvious than the original soil. The structural strength of loess decreases gradually with the increase of the number of dry and wet cycles. The greater the amplitude of the dry and wet cycles, the more obvious the weakening of the structural strength of loess is. The effects of moisture content, consolidation confining pressure, the number and amplitude of dry and wet cycles on loess structure were studied by triaxial tests after dry and wet cycles. The results show that with the increase of test moisture content, consolidation confining pressure, the number and extent of dry and wet cycles, the structure of loess decreases and finally tends to be stable. The SLOPE/W module of GeoStudio software is used to analyze the stability of slope with different slope and different times of dry-wet cycle, and the effect of dry-wet cycle on the stability of slope is studied. It is found that the slope safety factor decreases with the increase of the number of dry and wet cycles, and the slope is not more than 50 擄.
【學位授予單位】：西安理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU444

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