مجله مهندسی زیر ساخت های حمل و نقل
سال هفتم شماره 1 (پیاپی 25، بهار 1400)

In two decades, the roads of the roads in the desert areas of the desert have also been changed. Fiber-reinforced soil behavior modification studies have been performed by compaction, uniaxial compressive strength, and California load-bearing ratios. In this research, studies were performed on soil stabilization of constructing roads in sandy loam soils using cellulose nanofibers. The aim of this study was to stabilize the cracked pavement bed and strengthen it by adding nanocellulose to the soil. Physical and mechanical tests were performed to find the type of soil in the area and the effectiveness of nanocellulose. Samples in these experiments were combined with 0.5, 1 and 1.5% nanocellulose, The results obtained from the experiments showed that the addition of nanocellulose increased the liquid and plastisite between 21 to 27% and 60 to 65% and decreased the plastisite index between 25 to 40%, respectively. Optimal moisture and dry specific gravity increase and decrease, respectively. The uniaxial strength of the samples increased between 30 and 85% and the maximum CBR number up to 12 times., and the soil strength class in all samples was changed to "very good" subgrade for use in pavement. The rupture zone energy results also show that the increase in nanocellulose has a positive effect on the modified specimens and delays the occurrence of rupture cracks due to loading and volumetric changes. The response Surface statistical method was also used to predict objective variables.

Landslide is one of the natural disasters that occur every year with the changes that humans make in natural areas. Landslide assessment event requires accurate and reliable location information. Today, despite the progress of science, landslides can be evaluated with various techniques such as remote sensing. Therefore, this study was conducted with the aim of modeling the occurrence of landslides in the southwestern region of the country using remote sensing science and AHP method. For this purpose, ground points were first prepared to control and Remote sensing information using GPS. Then, different filters were performed on the Landsat sensor images. In addition, different parameters of slope, geological formation, distance from the river, etc. were investigated. The results showed that the Kernel Size 9 * 9 filter is one of the most suitable methods for highlighting structural features and geomorphology. Then, the weight of each parameter was determined using pairwise comparison and AHP method. Results of pairwise comparison of distance from fault with weight of 0.05 maximum weight, distance from river 0.07, communication network 0.09, rainfall 0.12, land use 0.15, vegetation 0.2, geological formation 3 / 0 and a slope of 0.59 was obtained. The weighting results showed that by merging the different layers, the high and very dangerous risk classes included 32.87 and 6.68 km of the length of the railway lines, respectively, with a total of 39.55 km or 92.8% of the total 39.55 km of the total length of Andimeshk-Doroud railway line.

It is very important to focus on treatments aimed at strengthening and improving the asphalt layer to increase the life of the pavement. Among the methods to increase the life of asphalt concrete pavement against structural failures that have been discussed in this study include the asphalt mixture modification approach (using Nano-silica) as well as asphalt reinforcement approach (using geogrid). In this study, based on the results of previous studies, the increase in fatigue life of these two approaches and their comparison with the fatigue life of control samples has been investigated. To determine the fatigue life of asphalt mixtures, the fatigue test of 4 points bending (4PB) beams under constant strain conditions (at 3 levels of 500, 700 and 900 micro-strains) has been used. The results show that by addition (in wet method) of Nano-silica to pure bitumen, the fatigue life of asphalt mixture is increased for both samples of Nano-silica modified and geogrid reinforced asphalt mixtures. For example, at a strain level of 500 micro-strain, the addition of 5% Nano-silica increases the fatigue life by about 193.9% (equivalent to 2.94 times) and the installation of a geogrid layer increases the fatigue life by about 212.4% (equivalent to 3.12 times). Also, asphalt mixtures reinforced with geogrid at the strain levels of 500, 700 and 900, respectively, increased the fatigue life of the mixture by about 6.5% (equivalent to 1.06 times), 61% (equivalent to 1.61 times) and 1.8% (equivalent to 1.02 times) compared to the samples modified with Nano-silica.

Since the most important factors affecting tire pavement noise are vehicle speed and road pavement and the quality of pavement is also dependent on changes in its distresses over time, thus we have investigated about affecting distresses of pavement(in the form of single distress and combination distress) and vehicle speed on tire pavement noise , acoustic data has been collected based on the statistical pass-by method at 28 points of asphalt pavements and at 50 , 60 and 70 km / h for three types of distresses, alligator cracking, raveling and polished aggregate, and a without distress mode as the basic mode for comparing distresses with it. finally, after collecting field data and reviewing and analyzing them with SPSS and MINITAB software, thus has been observed that affecting speed parameter and severity parameter on tire pavement noise in pavements with alligator cracking distress more than pavement with raveling distress. The impact of the combination of distresses on the sound pressure level has been investigated, as a result, has been observed that polished aggregate distresses have no significant effect on TPN in combination with distresses.

Fatigue resistance is one of the key specifications of asphalt materials that is of paramount importance in pavement design. Over time, because of the passage of traffic loads as well as exposure to different environmental conditions, pavement is damaged. Fatigue cracks in asphalt layers are accepted as a criterion in design methods. A variety of tests is employed in laboratory modeling, among which the four-point fatigue test is the best-adapted one to field conditions. In the present study, the effect of zycotherm additive on fatigue function of half-warm mix asphalt was tested. Other objectives of this study include assessment of fatigue life by wasted energy method and the association between energy parameters and traditional method (50% decline in stiffness modulus). In the current study, two types of calcareous and silica stone materials and 60-70 pure bitumen besides zycotherm additive of 0.1% of the bitumen weight have been utilized. The results revealed the improved fatigue life of half-warm mix asphalt due to the addition of 0.1% zycotherm. Mixtures containing calcareous aggregates performed better against fatigue compared to silica aggregates. Moreover, there was a very good relation between energy parameters and fatigue life. The ANOVA test result show that there was significant difference between fatigue life (Nf50، NS*N، NER) and PV parameters.