干湿循环对黄土抗剪强度和结构性及边坡稳定性影响的研究

发布时间：2019-03-22 06:10

【摘要】：黄土是一种第四纪沉积物,具有大孔隙、欠压密性以及湿陷性,在我国有着广泛的分布。随着我国工程建设的不断深入,黄土的工程问题也显现了出来。其中由于季节的交替,黄上在干湿循环作用下造成的破坏是工程中遇到的主要问题,会造成边坡、路基等的失稳破坏。因此研究干湿循环后黄土的强度和结构性的变化显得尤为重要。本文对干湿循环作用后的黄土进行直剪试验,研究干湿循环次数和干湿循环幅度对黄土抗剪强度和结构强度的影响。研究结果表明,经过干湿循环后的黄土试样抗剪强度降低。干湿循环作用主要造成黄土粘聚力的降低,而对内摩擦角几乎没有影响。干湿循环幅度越大、次数越多,黄土抗剪强度降低的越快、越多,在第一次干湿循环之后粘聚力降低最多。重塑土比原状土表现的更为明显。黄土的结构强度随着干湿循环次数的增加逐渐减小,干湿循环幅度越大,对黄土的结构强度的削弱就越明显。对干湿循环作用后的黄土进行三轴试验,研究试验含水率、固结围压、干湿循环次数和幅度对黄土结构性的影响。研究结果表明随着试验含水率、固结围压、干湿循环次数和幅度的增大,黄土结构性降低并最终趋于稳定。采用GeoStudio软件中的SLOPE/W模块对不同坡度,不同干湿循环次数后的边坡进行稳定性分析,研究干湿循环作用对边坡稳定性的影响。研究发现随着干湿循环次数的增加,边坡安全系数不断降低,且边坡坡度不宜超过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 掳.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU444

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