فهرست مطالب صادق قوامی جمال

Due to the importance of environmental issues and reducing energy consumption, the use of waste materials to improve the engineering properties of soils has been widely noticed by researchers in recent years. This research investigates the effect of carpet waste fibers on the compaction, hydraulic, and consolidation properties of kaolinite clay. Standard compaction, falling head permeability, and one-dimensional consolidation tests were performed on soil samples containing 0.5, 1, and 2 percent of fibers (relative to the dry weight of the soil). In order to investigate the effect of the fiber length on the results, the length of the fibers was changed from 6 to 30 mm. The results showed that the presence of carpet waste fibers decreases the maximum dry density and increases the optimal moisture content of the samples. Also, the carpet fibers increased the hydraulic conductivity of the samples and reduced the settlement of clay soil and its swelling index. So that the compression index and swelling index for the sample with 2% fibers with a length of 30 mm decreased by 35 and 64%, respectively. The presence of carpet fibers in the soil increases the speed of clay consolidation. From the obtained results, it was found that the changes in the consolidation properties of clay are more significant with the content of fibers compared to the length of the fibers.

Mamloo dam in Tehran province has been built to meet the needs of agricultural water in Varamin plain, but due to the drinking water supply in Tehran, a limited amount of stored water is supplied to the plain. One of the most important effects of the insufficient supply of surface water in Varamin plain is the reduction of groundwater aquifers and land subsidence. In this study, the effect of the Mamloo dam on land subsidence in the Varamin plain was investigated.

The changes in groundwater level and the unit hydrograph of the plain and quantitative changes of groundwater in the study area of Varamin plain located downstream of the dam were studied and analyzed in two periods before and after the operation of the Mamloo dam.

Based on the results obtained from the selected piezometric network and according to the division of the study area into northern and southern regions, the greatest amount of decline was in the northern part. After the construction of the Mamloo Dam, new evacuation points were created based on the potential maps in the northern and central parts, where the population and agriculture centers were located. In the south, due to the type of geological structure and less alluvial thickness, the emptying of the pores of the aqueous layer has led to subsidence in some areas. Finally, the adaptation of the areas with the greatest decrease in groundwater discharge to the areas with the highest vertical displacement in the southern and central regions in the radar maps was quite clear.

By investigating the results obtained from the analysis of the drop of piezometers in the study area of ​​Varamin plain and the expansion of the number and depth of deep wells in the mentioned plain, the change in the underground water flow regime and the reduction of the aquifer volume are clear. After the construction of the Mamloo dam, the amount of this drop has increased, especially in the lands of the northern part. In addition, the lack of proper planning in meeting the needs of the agricultural sector of the plain, which has a major share in the consumption of water obtained from underground sources, has caused major challenges in the climatic and social conditions downstream of the dam. Due to the construction of the Mamloo dam at the entrance of the Jajrood River to Varamin plain, the level of the water table has decreased over time due to the significant reduction of surface flow to the region. This decrease had higher values ​​in the northern half of the plain and in the areas where the thickness of alluvium is greater. Based on the output of satellite and subsidence maps, the areas that experienced more discharge and drop during the statistical period correspond to the areas with more subsidence in the subsidence maps.

Due to the problems and high cost of real-scale experimental studies and on the other hand, the ability of small-scale models in geotechnical centrifuges to establish physical similarity and take into account the real stresses in the model for a correct understanding of deformations and rupture mechanisms, major experimental studies on the phenomenon of surface faulting has been done using by geotechnical centrifuge. In this research, the concept of physical modeling with a geotechnical centrifuge, scale rules, constraints, and sources of error in simulating the interaction of dip‐slip fault with underground tunnels and shallow foundations are investigated. Finally, by minimizing modeling errors, the interaction of reverse fault with underground tunnels, as critical transport infrastructure, and the shallow foundation is simulated. The results showed that in reverse fault propagation in sandy soil when the rupture reaches the surface, its dip angle decreases, and at the ground surface, shear ruptures and tension cracks are created which can damage structures and infrastructures. The presence of the tunnel in the rupture path causes the fault rupture path to change and the fault rupture zone to increase at the ground surface, which can affect the performance of surface structures and buried structures adjacent to the tunnel. In the propagation of reverse fault rupture, the presence of the surface structure on fault outcrop, overburden pressure due to the structure, causes the rupture path to deviate to the right corner of the foundation and the structure to rotate. Besides, on the right side of the foundation, a fault scarp was observed, which was consistent with field observations in previous earthquakes with surface fault rupture.

Cement asphalt emulsion mortar (CEAM) as a critical and complex engineering material for slab ballastless track is widely used in high speed railways and road pavements. Damping and cracking characteristics of CEAM are very important to resist vibration and the deformation caused by repeating loads. Furthermore, Cement is the fundamental constituent of CEAM, which is notorious for the environmental pollutant. Accordingly, reducing cement consumption has been a significant concern. This study evaluated the effects of using two types of supplementary cementitious materials (SCM), i.e. fly ash (FA) and granulated blast furnace slag (BFS) in corporating with cement kiln dust (CKD) as cement replacement, on the mechanical properties and cracking characteristics of cement emulsified asphalt mortar. To reach the objectives of the study, different experimental tests (i.e. Uniaxial Compressive strength (UCS), indirect tensile (IDT) strength, Moisture susceptibility and semicircular bending (SCB)) were conducted. The results showed that the replacement of 30 percent of cement by fly ash leads to significantly improve the compressive strength and indirect tensile strength of prepared CEAM. Furthermore, all the proposed CEAM containing different percentages of SCMs had ITSR more than 0.8 which pass the standard requirement. The consequences of CEAM cracking resistance indicated that the 30 percentage replacement of cement by BFS considerably enhanced the J-integral of CEAM which results the better cracking resistance of prepared mixture. Moreover, the replacement of 50 percent of cement in CEAM by supplementary cementitious materials revealed that the proposed CEAMs had proper unconfined compressive strength, capability to resistance against crack initiation and propagation and also sufficient endurance against moisture failure. Finally, it can be concluded that the examined CEAMs in this study can be presented as eco-friendly CEAM which had enough resistance against the repeated train and varying environmental loadings.

Clay soils generally have low strength and bearing capacity. Chemical stabilization commonly used to improve the geotechnical performance of fine-grained soils. In recent years, waste material like fly ash was employed for soil stabilization in geotechnical engineering not only for the economic aspect but also from the environmental point of view. This paper presents the results of an experimental investigation to evaluate the effect of class C and class F fly ashes on geotechnical parameters of clay soil with high plasticity. The Atterberg limits, compaction, unconfined compressive strength and California bearing ratio (CBR) are particularly investigated. The test results show that with the increase in the amount of fly ash, while the maximum dry density values decrease, the optimum water contents increase. The liquid limit and the plasticity index values decrease when the fly ash amount is increased to the level of 25% and then increase after this level. The highest unconfined compressive strength and California bearing ratio were obtained when the fly ash content was 25%. The curing period significantly affected the compressive strengths of mixtures. The soil samples with class C fly ash is more efficient on the compressive strength, compared to class F fly ash.

Considering the geotechnical problems caused by low strength clayey soils is important in construction projects. Chemical stabilization with additives such as cement is a common method to improve the engineering properties of clay soils. In spite of the acceptable effects of cement on strength of soils, the cost of this additive and its destructive effects on the environment should be of concern. This has led the researchers to use by-products and waste materials. Cement Kiln Dust (CKD) is a powdery by-product of the Portland cement manufacturing process. In this paper, the geotechnical parameters of cement and cement kiln dust stabilized kaolinite clay are compared. For this purpose, Atterberg limits, standard proctor, unconfined compressive strength, and California bearing ratio tests were conducted on specimens containing 5, 10 and 15% cement and CKD (by dry weight of the soil). The results show that the cement and cement kiln dust increase the soil strength. It was seen that the unconfined compressive strength of the specimen with 15% CKD is equal to the specimen with 10% cement after 28 days of curing. It is evident from the scanning electron microscopy analysis of specimens containing cement and CKD that calcium silicate and aluminate hydration products reduce the volume of the void spaces and join the soil particles, leading the strength to increase.

In many cases, tunnels that are considered critical underground infrastructure for urban transportation are built in high seismicity areas and active fault zones. Fault displacements during earthquakes may interact with sub-surface structures leading destructions. Recent earthquakes, such as the 1999 earthquakes in Turkey and Taiwan, revealed that by avoiding construction in the fault zone, the structures are not completely safe for fault threats. Therefore, it is necessary to evaluate the interaction mechanism between structures and fault rupture for effective design to reduce the hazards associated with surface faulting. Verified finite element modeling is used in this study to investigate normal fault-tunnel interaction. The effect of different parameters such as horizontal tunnel distance relative to rupture path in free field condition, tunnel depth, tunnel rigidity, and fault angle on fault–tunnel interaction are studied. The results indicated that the tunneling in the path of fault rupture causes a diversion of rupture path. The burial depth of the tunnel and its diameter are effective parameters in the propagation of the shear zone in the sand layer and surface deformations. With increasing the tunnel depth, the rupture path inclines more, and the shear zone is extended over a wider area. Comparison of numerical results demonstrated that surface displacement in normal fault of dip angle 45° is higher than 60°.

Composite materials are used widely in construction industry. Their resistance to corrosion, stability, lower maintenance cost and other pros compared to other new materials make it promising for further usage. However, utilizing these materials suffers from some challenges such as environmental concerns, being costly and etc. This study compares its advantageous and disadvantageous in construction industry.

Achievement and success in significant industrial and constructional projects requires systematic approach in planning and controlling how the project is done, considering performance method and cost. In current research, the importance of planning and controlling of project, the advantages of applying this approach and the steps of planning and controlling of project have been studied.

Many of activities in Civil Engineering field such as railways, roadways and dam constructions are highly connected and related to rock mines. Trenches of rocks, foundation on rocky bases, tunnel digging and searching through mines in rock bulks are included in such a kind of activities. The stability of both constructed trenches and natural trenches are necessary to be satisfied and analysed. In this study, the parameters which are effective on the stability of rocky slopes will be illustrated and different methods in designing these slopes will be discussed.

In situ natural soils are not usually suitable to bear the structures load. In this case, the soil needs reform in its engineering specifications. One of the improving methods is stabilizing the soil by adding lime, cement, ashes, cement kiln dust. In this paper, besides introducing the cement kiln dust, some recent studies about its effect on geotechnical parameters of soil are represented. Cement kiln dust is a lateral product of the process of producing Portland cement which is obtained from kiln output gases. Investigations show that adding the dust increases unconfined compressive strength, compactness parameters and plasticity features of soil.