Abstract
Drying-induced cracks are frequently observed in soils, which can severely influence the mechanical parameters of soils in geotechnical engineering applications. In addition, geohazards can also be accelerated with the formation of preferential path in slopes caused by cracks in soils. This study aims to analyze the cracking behaviors and mechanisms of a special soil collected in northwestern China using experimental methods. Local displacements and strains can be obtained and analyzed with Digital Image Correlation (DIC) method. Combined with DIC method, the tensors maps with total “mechanical” principal strain are drawn. Cracks in mixed opening-sliding mode are identified and the curling phenomenon of soils is observed in situ. Three typical types of crack patterns are observed, which are “T,” “Y,” and “wave-ring,” respectively. Crack pattern of “T” is more frequent than the other two types. The identification of cracking behaviors and mechanisms is helpful for the analysis of mechanical properties of soils and the prevention of geohazards in northwestern China.
Highlights
Cracks in soils are commonly observed in natural environments. e existence of cracks will change the mechanical parameters of soils such as strength, bearing capacity, permeability, compressibility, etc. erefore, the hydromechanical properties of soils are greatly influenced by cracks [1,2,3,4,5,6,7,8,9,10,11,12,13]
Tang et al [21] believed that water content is an important factor affecting the generation of soil cracks. e factor that determines the degree of cracking is the gradient of water content inside the soil. e rate of soil dehumidification affects the gradient of water content, which is mainly related to hydraulic factors such as soil evaporation space. erefore, the variation of water content is an important factor leading to soil cracking. e precipitation, air temperature, and humidity in the natural environment all influence water content of soils
To better observe the cracking process of soils related to desiccation, an experimental system was set up in this study. e tests were carried out in the laboratory under a constant temperature of 25°C and a relative humidity equal to 30 ± 5%. e soil sample in a slurry state was spread on a circle mold made of quartz, the diameter of which is 200 mm. e thickness of the soil sample is 10 mm. e support of the mold is nonwettable to water. e friction between the samples and the base materials is nearly zero. e initial water content of the soil sample is equal to its limit liquidity (36%)
Summary
Cracks in soils are commonly observed in natural environments. e existence of cracks will change the mechanical parameters of soils such as strength, bearing capacity, permeability, compressibility, etc. erefore, the hydromechanical properties of soils are greatly influenced by cracks [1,2,3,4,5,6,7,8,9,10,11,12,13]. It is generally believed that soil cracks are mainly caused by the evaporation of water and uneven volume shrinkage under dry conditions [18]. Erefore, suction and tensile strength are considered to be the two key mechanical parameters that control the formation of cracks in soils [5, 19,20,21]. Peron et al [22] found that, for homogeneous soils, boundary constraints and water gradients are important reasons for the generation of tensile stress and the formation of soil cracks. Tang et al [21] believed that water content is an important factor affecting the generation of soil cracks. E factor that determines the degree of cracking is the gradient of water content inside the soil. Erefore, the variation of water content is an important factor leading to soil cracking. Air temperature and humidity can indirectly affect soil cracking by adjusting the evaporation rate of soil moisture [10]. e natural environmental temperature is an important external factor that affects the Advances in Civil Engineering development of soil cracks, while the initial water content and dry density are important internal factors that influence the soil cracking
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