Evaporative Cracking Characteristics of the Embankment Soil Affected by the Saline Concentration

Embankment soil affected by saline can not only cause roadbed settlement, frosting, and road cracks but also cause corrosion and cracking of roadbed pipelines, which seriously affects the stability of the road. Water evaporation and dry cracking of the saline soil mainly cause soil swelling, poor water stability, and corrosive characteristics of the embankment soil. In this study, the evaporative cracking characteristics of soil with different saline concentrations were investigated. The results showed that the moisture content decreased linearly with the drying time in the early evaporation process, subsequently decreased slow down in the mid-term evaporation, and finally become got and remain a residual moisture content, which are 46.39%, 44.05%, 42.70%, and 40.27% with the increase of the saline concentration. The evaporation process with different saline concentrations in the soil can be divided into three stages: uniform evaporation stage, slow down evaporation stage, and equilibrium evaporation stage, which was consistent with the moisture content change. With the development of the drying time, the cracks gradually appeared on the soil surface, gradually deepened in the soil, and expanded the crack network. The development of cracks can be divided into three stages: the cracking preparation stage, the crack development stage, and the crack stable stage. The cracking began at high evaporation rate under high saline concentration, and the fractal dimension remained stable under similar saline concentration. The fractal dimension was gradually increased with the decrease of the moisture content and the increase of the saline concentration, respectively. The soil began to crack with larger moisture under high saline concentration. The drying cracks in the nature were consistent with the configuration of the cracks formed in the experimental results.

Reflection Crack Analysis of Asphalt Overlay on Cement Concrete Pavement Based on XFEM

Based on the improved Paris formula, the reflection cracking characteristics of asphalt overlay on the cement concrete pavement are carefully scrutinized. The fatigue life is also predicted through the indoor simulation tests and establishing the two- and three-dimensional extended finite-element method (XFEM) models. Four fracture factors of the Paris formula in the asphalt mixture are appropriately calculated by fitting the N-a curve of the indoor test, and their predicted values are then exploited in the numerical simulations. The obtained results show that the numerical model can successfully predict the results of the indoor simulation test. It indicates that the XFEM has apparent advantages in examining the reflection cracking of the asphalt overlay on the cement concrete pavement.

Experimental and Numerical Analysis of Soil Cracking Characteristics under Evaporation

There are numerous cracks on soil surface in nature. These cracks are mainly formed by the continuous water loss and shrinkage of soil under evaporation. Cracks have an important effect on the properties of soil. The analysis of soil moisture movement and cracking characteristics under evaporation is of great significance to the engineering construction in the cracked soil area. In this work, an experimental study was conducted to investigate the development of soil cracks. Crack geometrical parameters were acquired at various developmental stages. According to this, the crack evolution characteristic was described qualitatively. The law of soil water movement was analyzed through the numerical simulation of evaporation effect on cracked soil. The relationship between soil moisture content and crack width was revealed, and the dynamic prediction of crack development under evaporation was realized. The results show that the development and evaporation process of soil cracks can be divided into three distinct stages, and the longer the stable evaporation time, the greater the development of cracks.

Shear and flexure behavior of hybrid composite beams with high performance concretes

Shear and flexure performances of composite beams with different engineered cementitious composites (ECC) to self-consolidating concrete (SCC) depth ratio were investigated. Shear reinforced composite ECC/SCC beams showed similar behavior compared to their non-shear reinforced counterparts until the formation of diagonal cracks but exhibited higher ultimate shear resistance and ductility. Compared to the full depth SCC and full depth ECC beams, non-shear reinforced composite ECC/SCC beams showed higher ductility and energy absorption capacity. Composite ECC/SCC beams showed higher number of cracks with lower crack width because of fiber bridging and micro-cracking characteristics of ECC. Code based equations and other design specifications were conservative in predicting shear strength of shear/non-shear reinforced composite ECC/SCC beams. Composite ECC/SCC flexure beams showed satisfactory flexural performance compared to their full depth ECC and SCC counterparts.