南京市马汊河膨胀土变形特性研究

Study on Deformation Characteristic of Expansive Soil in Macha River of Nanjing

膨胀土反复的胀缩变形及裂隙的发展,是膨胀土边坡失稳的先决条件。在日晒雨淋的作用下,膨胀土干湿交替,大气影响深度范围下的膨胀土反复胀缩变形,通过对室内试验,通过干湿循环试验模拟膨胀土在自然环境的特性,研究表明:随着干湿循环次数的增多,膨胀土的相对膨胀率逐渐减小,绝对膨胀率增大,浸水后的最终膨胀率趋于稳定,干湿循环过程中,膨胀后试样高度增加,裂隙增多,边缘土粒首先发生破坏,后向中间发展,直至裂隙贯通。

The repeated expansive deformation and crack development of expansive soil are the precondition of expansive soil slope instability.The dry and wet expansive soils are alternated by being exposed to the sun and rain.The expansive soil is repeatedly expanded and contracted to deform under the range of atmosphere influence depth.The laboratory experiment and the dry-wet cycle test can simulate the characteristic of expansive soil in the natural environment.The study shows that the relative expansive rate of expansive soil gradually decreases and the absolute expansive rate increases with the increment of the dry-wet cycle times.The terminal expansive rate tends to be stable after immersion in water.In the course of dry and wet cycle,the height of the test example increases and the crack increases after expansion.The marginal soil particle is firstly destroyed and then developed to the middle until the thorough crack.