جستجوی مقالات مرتبط با کلیدواژه « خاک مسلح » در نشریات گروه « عمران »

Various geosynthetics reinforcements used to stability of soil slopes and geocells due to the three-dimensional nature of cells proposed by many researchers. Most current researches of reinforced soil analyze are two dimensions, which is inefficient for modeling the 3D geocell element. In this paper, the static and dynamic response of reinforced soil studied by three-dimensional modeling.For this purpose, Plaxis-3D finite element software has been used to modeling with different geometric characteristics. The results of this study show that tVarious geosynthetics reinforcements used to stability of soil slopes and geocells due to the three-dimensional nature of cells proposed by many researchers. Most current researches of reinforced soil analyze are two dimensions, which is inefficient for modeling the 3D geocell element. In this paper, the static and dynamic response of reinforced soil studied by three-dimensional modeling.For this purpose, Plaxis-3D finite element software has been used to modeling with different geometric characteristics. The results of this study show that the geometry of the wall including the height and angle of the embankment as well as the arrangement of geocell cells at different level (height) and the length of the penetration affect the lateral displacement and the embankment stability coefficient.he geometry of the wall including the height and angle of the embankment as well as the arrangement of geocell cells at different level (height) and the length of the penetration affect the lateral displacement and the embankment stability coefficient.

Mechanical properties of mechanically stabilized earth structures depend on the mechanical parameters of the fill material, tensile strength of reinforcement elements, and the interface properties of the geosynthetic and the fill material (Ouria and Mahmoudi, 2018). Optimal design of reinforced earth systems demands for a pullout capacity of reinforcements proportional to their tensile strength (Ouria et al., 2019) (Ouria et al., 2021) (Ouria et al., 2022). That is why the utilization of high strength reinforcements in reinforced earth structures has not been developed extensively. Anchorage of high strength reinforcements requires long anchorage length of mechanically anchored ends. On the other hand, rapid development of societies requires renewal of several structures and substructures (Ouria et al., 2020)(Ouria and Heidarly, 2021)(Ouria and Sadeghpour, 2022). The replacement of existing substructures requires new materials and also produces demolition waste material in large quantities (Vieira and Pereira, 2015). The huge rate of the production of demolition waste material in the recent years raised concerns about the harmful impacts of these material in the environment (Savadkoohi and Reisi, 2020). Recycling of these waste material and their utilization in new projects could be proper step in response to the raised concerns. In this study the applicability of demolition waste material in the reinforced soil structures was investigated in the laboratory.

This paper experimentally examines the effect of geotextile layers on the undrained behavior of cement-stabilized clay specimens using unconfined compressive strength (UCS) tests. Accordingly, the low-plasticity clay specimens were remolded in three different moisture contents, including optimum moisture content and two other ones corresponding to 90% relative compaction. The clay specimens were also stabilized by cement with various percentages equal to 3, 5, and 7% of the dry weight of the soil. The stabilized clay specimens were then cured in 7, 14, and 21 days prior to performing the unconfined compressive tests. In order to investigate the effect of reinforcement type, the stabilized clay specimens were reinforced with two types of non-woven geotextiles with different values of tensile stiffness. Results of experiments showed that reinforcing cemented-clay specimens with geotextile sheets improves the mechanical properties such as maximum compressive strength, residual strength, and rupture strain of reinforced specimens compared to unreinforced ones. The greatest increase in compressive strength occurred in specimens reinforced with three geotextile layers, which had an average 37% increase in strength compared to non-reinforced specimens. The comparison between reinforced specimens with two different geotextiles showed that increasing the tensile strength of the geotextile increases the compressive strength, rupture strain, and residual stress of the reinforced specimens.

The interaction parameters between soil and reinforcement at their interface play a critical role in influencing the mechanical behavior of reinforced soil systems. Interaction parameters between soil and reinforcement influence reinforced soil behavior mechanically. In this research, the effect of the size of soil grains and the stiffness of the reinforcement on the pull-out resistance of the reinforcement from the soil has been investigated in a laboratory. The pullout resistance of three types of reinforcements with different stiffness in three types of soil with different grain sizes has been investigated. Pull-out tests have been performed at three stress levels of 50, 100, and 150 kPa. To investigate this issue and determine an evaluation for the stiffness of the reinforcement, a device has been built to measure the penetration of solid soil grains in the reinforcement. The results of the tests show that the penetration of soil grains into the reinforcement has a significant impact on the resistance of the reinforcement to being pulled out of the soil. The amount of penetration of solid soil grains into reinforcement increases by reducing the stiffness of the reinforcement and increasing the size of the diameter of the soil grains. For each specific vertical stress level, the greater the penetration of solid soil grains into reinforcement, the higher the pull-out strength of that reinforcement. The results show that with the increase in the diameter of the solid grains of the soil, the pullout resistance of the reinforcement has also increased, but this increase has been more significant in the case of reinforcement with lower stiffness compared to reinforcement with higher stiffness. Also, the difference in the pullout resistance of three reinforcements with different stiffness in fine-grained soil was less than the difference in the pullout resistance of three reinforcements in coarse-grained soil, which indicates the simultaneous effect of reinforcement stiffness and soil grain size on pullout resistance.

Due to spread of automotive industry the worn tires are being consider as a one of the Environmental pollutants in recent decades because of the lack of decomposition in nature. The use of tires crumb with mixed soil is provided as a one of the solutions to prevent environmental hazards caused by tires burial. According to the tires properties, such as elastic behavior, low water absorption and the appropriate cost to use it in the form of crushed, they can be used in arming and improving the properties of earth materials. In this article, the optimal percentage of tires crumb in the sand to increase its shear strength parameters as well as the effects of adding tires crumb on Displacement-load curve by using large-scale direct shear test (box 30x30 cm) has been studied. For this purpose, sand with different percentages of tires crumb and various value of normal stresses in direct shear has been tested and the percentage of optimal tires crumb which the shear strength is maximum for it determined. Since the shear strength of soils is because of angle of internal friction and viscosity, the effect of tires crumb on each of these parameters is studied. Results shows that adding tires crumb cause to increase the capacity of plasticity, viscosity, angle of internal friction and therefore to increase the shear strength of the sand.

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.

Granular materials are widely used in construction. The cost and environmental impact of supplying natural aggregates force the construction industry to look for alternative materials for engineering applications. The interface shear strength properties of recycled construction materials including concrete and asphalt with geogrid as alternative backfill materials in reinforced structures were investigated by using Large-scale Direct Shear Test (LDST) apparatus. Also, a comparison is made between the recycled materials and a natural material with the same physical characteristics and grain size. Geosynthetics are mainly used to stabilize and reinforce different types of earth structures such as slopes, retaining walls, bridge abutments, and foundations. In these cases, the interaction between soil and geosynthetic has a vital role. Three types of single-stranded geogrids were tested as reinforcements. The results showed that reinforcement increases the shear strength and internal friction angle. The tensile strength of geogrids does not have effect on the interface shear strength as the geogrids do not reach the failure state during shear test. The shear strength coefficient for these materials was greater than one, which indicates a strong interaction between the geogrid and the materials. Recycled materials including concrete and crushed asphalt have good shear strength and can be used as an alternative to natural materials in reinforced soil retaining walls, although their shear behavior is slightly different. In general, due to the involvement of these aggregates with the geogrid, it leads to an increase in the shear strength of the interface of these materials and the geogrid to the materials themselves. The shear behavior of natural materials and concrete changes from a slightly softening behavior to a hardening behavior on the interface, a process that is more severe in the case of asphalt. Also, the volumetric behavior of the interface of natural materials and recycled concrete with geogrid is more extensive than the materials themselves, the opposite is true for asphalt. Recycled asphalt materials have a lower interaction coefficient than natural materials and recycled concrete. This reason could be attributed to bitumen coating on recycled asphalt aggregates. In general, recycled concrete and asphalt materials provide the minimum shear strength parameters when reinforced with geogrids.

In this research, the effects of the wraparound anchorage on the bearing capacity of a spread footing on sand reinforced by carbon fiber reinforced polymer strips were studied experimentally and numerically. A steel box with the dimensions of 100×100×70 cm was used as a test setup and the spread footing was simulated using a steel plate with the dimensions of 20×20×2.5 cm. Also, a numerical model was developed by FLAC3D software to simulate the physical model for further investigations. Laboratory tests were conducted on unreinforced and reinforced models with and without wraparound anchors with different lengths. The results of these investigations indicated that the effect of the wraparound anchorage on the bearing capacity of the foundation was highly dependent on the return length of the anchor. Its effect on the improvement of the bearing capacity of the foundation was noticeable when the length of the anchor was long enough that the end of the reinforcement placed under the footing. Otherwise, the effect of the wraparound anchor on the improvement of the bearing capacity of the footing was negligible. Depending on the length of the return anchor, two distinct load-settlement behaviors were observed. When the length of the return anchor was not long enough, the bearing capacity of the footing showed some improvement in low settlement levels, but it approached the bearing capacity of the footing with unanchored reinforcements as the settlement was increasing. There was at least 10% improvement in the bearing capacity in this situation. For models with long return anchors, increasing the settlement of the footing increased the bearing capacity of the footing when compared to the behavior of reinforced model without wraparound anchor. The improvement of the bearing capacity of the footing was up to 27% for long anchors depending on the length of the wraparound anchor. The results of the numerical simulations indicated that the wraparound anchorage changed the stress distribution and increased the confinement of the soil elements located under the footing. Increasing the length of the return anchors led to a uniform distribution of the confining pressure under the footing.

This paper presents the results of an experimental study on the effect of the pattern of reinforcement placement in reinforced soil on the bearing capacity of a strip foundation. A steel box filled with sand with the dimensions of 100×25×30 cm (Length, widths, and height) was used as the test base. The strip footing was simulated by a steel plate with dimensions of 25×7.5×2 cm. The sand used in this study was a poorly graded sand (SP) according to the unified soil classification system. A woven type geotextile was used as reinforcement. The effect of the reinforcement’s placement pattern on the bearing capacity of the foundation was investigated with nine different layouts including single, double, and three-layered reinforcement layouts. All the specimens prepared with a similar initial unit weight and void ratio. The tests conducted using a displacement-controlled loading device. The loading was applied with a rate of 1 mm/second. All the tests repeated at least three times to assure the accuracy and the repeatability of the results. The results of these tests indicated that the bearing capacity of the foundation increases as the length of the reinforcement increases but up to a certain limit and then remains constant. Although increasing the number of reinforcements layer increased the bearing capacity of the foundation, however, the effectiveness of the geotextile in the improvement of the bearing capacity decreased. Placement of the reinforcements in a discrete pattern improves the effectiveness of the reinforcement on the bearing capacity improvement. In multi-layer reinforcement layouts, using discrete strips of reinforcements in each elevation without overlapping with upper- and lower-layers of reinforcements, resulted the maximum efficiency of reinforcements influence in the improvement of the bearing capacity of the foundation. In the recent case, for a specific cross-sectional area of the reinforcement, the bearing capacity of the foundation could be increased by 20% using 17% less reinforcement. The results of this study indicate that the layout of the reinforcement pattern is a very important factor in the bearing capacity of foundations on reinforced soil. With a proper placement of reinforcements, the maximum bearing capacity of the foundation could be achieved with a minimum amount of reinforcement material.

Mechanical specification of the interface of soil and reinforcement is one of the most important parameters of the design and construction of reinforced soil systems. Anchorage length of the reinforcement is determined based on the soil-reinforcement interface parameters. Required long anchorage lengths restricts the application of reinforced soil systems. Improving the mechanical parameters of the soil-reinforcement interface could be used to develop the applications of reinforced soil structures in projects with limited space. In this research, the cement treatment of the interface of the soil and reinforcement was employed to improve the pull-out capacity of the reinforcement and consequently to reduce the anchorage length. The effect of the cement treatment on the pull-out capacity of the reinforcement was studied in the laboratory. Also, the effect of the increased thicknesses of the reinforcements resulted from the cemented layers adhered to the reinforcement surface was investigated. The laboratory tests conducted using specially developed pull-out test device. The tests conducted on high-strengths woven geotextiles with different thicknesses with both pristine and cement treated interfaces. Cement treatment carried out with 1.5 g/cm2 portland cement sprayed on water saturated geotextile. The results of tests conducted on pristine reinforcements with different thicknesses showed that increasing the thicknesses of the reinforcements increase the pull-out capacity. Also, the cement treatment increases the pull-out capacity of reinforcements.

Retaining walls are walls that maintain the pressure caused by the existing state of the difference in levels caused by embankment, excavation or natural factors. In this study the stability of the flexible walls and the type of reinforced soil walls are evaluated to examine the stability and design the retaining walls with reliability method which gives more realistic results than other design methods. Reinforced soil wall is a special material that is formed by the combination of the soil and the reinforcement member. Basically the soil is weak in stretching and cutting and the idea of reinforced soil wall is in fact the solution to this problem. There are many uncertainties in civil engineering and in particular in the geotechnical discussions the discussion of the uncertainty of the parameters is much more evident because the anonymity of the soil behavior. The traditional methods of evaluated the stability of reinforced soil walls which are usually based on empirical judgments such as the concept of a coefficient. Efforts to quantify uncertainties causing genesis of probabilistic methods. Probabilistic analysis in comparison with definite analysis the uncertainties in the calculations and instead of using the confidence coefficient in the project safety level it usually uses the probability of failure or the reliability index

Current design of Geo synthetic-reinforced soil (GRS) walls, shows that the horizontal deformations in the walls increases rapidly with height. To take advantage of both the aesthetics and the economics of GRS walls while considering high heights, multi-tiered walls are often used. In this context, 12 models of the walls were constructed and their performance was determined under static loading. This study presents a series of model tests on the GRS walls in a tiered configuration, to evaluate the effects of factors, including the offset distance between adjacent tiers and number of tiers, on the lateral displacements of the wall facing and ultimate bearing capacities of the strip footings on the multi-tiered GRS walls. The ultimate bearing capacity and wall deflection can be significantly improved by increasing the number of tiers wall and increase of tier-offset. Interaction between the upper and lower walls significantly influences the tier-offset, and the interaction between the walls, significantly increase in the horizontal deformation in the wall face for the upper wall. With an increase in the offset distance, the lateral displacement decreased significantly, particularly in the upper tier. The experimental results showed that, the Performance in Four layers of reinforcement, and two tier walls, the optimum offset distance obtained for D/H= 0.35. When the offset becomes significantly large, each tier functions independently

Reinforced soil is a common technique to improve the soil properties and can be used in design of foundations and retaining earth structures. Reinforced earth structures are embankments which are reinforced with reinforcing elements such as geogrids, steel straps, etc. This study evaluates the strip footing bearing capacity that rest on near the geogrid reinforced retaining walls in saturated and dry sandy soil conditions. The previous researches have indeed studied the effects of many different parameters on the strip footing bearing capacity including the number of reinforcing elements, reinforcement depth, vertical distance of the reinforcing elements, etc. However, the retaining walls behavior in saturated embankment conditions has not so far been studied up to now so the emphasis in this article was to study the effect of saturation condition on the footing bearing capacity near the reinforced walls. For this purpose small scale laboratory model tests were carried out to investigate the behavior of strip footing bearing capacity that rest on near the geogrid reinforced retaining walls. A steel frame model box with inner dimensions of 0.5 m × 0.5 m in plan and 0.5 m in height was used. One side of the test box was made of Plexiglas for observations during the tests. The strip footing was made of a steel plate 0.49 m in length, 0.05 m in width and 0.02 m in thickness. An aluminum plate with thickness of 3mm used as retaining wall model. A two-way geogrid sheet with a tensile strength of 20KN/m was used to reinforce the sand bed. The sand bed prepared by sand raining technique and a water tank placed on top of the frame to saturate the bed and Overall, 90 tests were conducted. To evaluate the effect of geogrid length on strip footing bearing capacity in dry condition, three different lengths (L/B=3, 4, 5) was used. The bearing capacity of the strip footing increases with an increase in the geogrid length. Increasing of geogrids lengths prevents expansion of the failure area and allows for wide distribution of applied loads. Based on the BCR diagrams reveals that in most diagrams, the slope of the first part (i.e. L/B=3 to L/B=4) is larger than the slope of the second part, which indicates that an increase in the length to the L/B=4 level causes a significant change in the strip footing’s bearing capacity. As a result, larger increases do not have significant effects on the strip footing’s bearing capacity. Therefore, in this study, the L/B=4 length ratio was recommended as the optimum ratio considering economic problems. To study the effect of the geogrid depth on the footing bearing capacity in the saturated embankment, the bearing capacity at four different depth ratios of u/B=0.25, u/B=0.5, u/B=0.75, and u/B=1.0 are used and that compared with dry condition. The results are showed that increasing the geogrid depth introduced a descending trend in the bearing capacity of the strip footing, so that the full capacity of the geogrid sheet could not be utilized. One reason for this is that increasing geogrid depth would compress the soil between the footing and the geogrid, leading to large settlements. Considering the conditions of the present study, the depth ratio of u/B=0.25 selected as the optimum ratio.

Successful use of geosynthetics is ensured in a given geotechnical application, as it is not only compatible, but also effective in improving the soil properties when appropriately placed. This study investigates the behavior of unreinforced and reinforced sandy soil with nonwoven geotextile using CBR tests. The soil used, has poor CBR value due to its low compaction and moisture percent. In a series of tests, Geotextile is placed in various depths from the top of samples. The effect of thickness of dense layer (with 97% compaction) on the soft subgrade is also investigated, and the results are compared with reinforced condition. To study the effect of embedment depth of reinforcement, the geotextile layer is placed in depths of 1, 1.5, 2, 3, 4, 6 and 8 cm from the top of the sample. Furthermore, a comparison between reinforced samples with one layer and two layers of geotextile is done. The results of the CBR tests demonstrate clearly considerable amount of increase in CBR value of soil with geotextile reinforcement. It is also shown that the maximum increase in CBR value is obtained when one layer of geotextile is placed at depth of 1.5 cm. The rate of increase in CBR value was reduced with increase in the placement depth of reinforcement layer. The thicker dense layer leads to more increase in CBR. In the same density and thickness of the replaced soil layer, the highest increase in the CBR value was achieved when the sample was reinforced by two layers of geotextile. To achieve a specified design CBR value, using less depth of replaced soil layer in the reinforced subgrade is possible as compared with unreinforced subgrade. For example, using a depth of 1.5 cm and 3 cm of replaced soil, CBR value equaling 6 is achieved for reinforced and unreinforced subgrades, respectively. Although the replacement of compacted soil layer or the use of reinforcement layer could increase the bearing capacity, achieving a certain capacity needs to consider the details of economic issues and performance limits.

Geocell is a three-dimensional geosynthetic product which can be used to stabilize foundations by increasing bearing capacity and reducing settlements. Geocells have completely dierent mechanisms compared to the traditional forms of geosynthetics (planar geosynthetics). Their three dimensional geometry causes extreme lateral con nement for the in lled soil, which leads to an increase in soil strength and stiness and a decrease in surface permanent-deformation.
Many laboratory and eld tests have demonstrated the eectiveness of geocell reinforcement systems in dierent elds. Due to several advantages, the geocell is in the process of practical development. However, a considerable gap exists between applications and theories for mechanisms of geocell-reinforced foundations. There are relatively extensive laboratory studies in the eld of geocell reinforcement, but, because of its complexity, numerical modeling of geocell reinforcement, which is essential for investigating its behavior, has rarely been undertaken.
This paper presents a numerical model of geocell reinforced foundation sand beds. In this numerical study, in order to simulate the three dimensional nature of the geocell accurately, the geocell and soil are simulated separately using the 3D Finite Dierence Method (FDM) of FLAC3D. The geocell is simulated using geogrid structural elements, and the elastic-perfectly plastic Mohr- Coulomb model is used for modeling the behavior of soil. In order to verify the modeling, at rst, a single geocell reinforced soil is modeled and compared with the equivalent laboratory test presented in the literature. Then, the model is extended to geocell foundation beds.
Finally, in this research, the placement conditions under which the geocell layers have the highest eciency (highest bearing capacity with the least cost) are determined in order to reduce the costs as much as possible. Also, a comparison is made between the performance of the 3D geosynthetic reinforcement and planar form with the same mass of used material (as two reinforcing systems with similar materials but dierent behavior mechanisms) to determine the system with higher eciency

Soil, as a natural gravel environment, has a good resistance to stress and shear, and its resistance to tension is very weak. The reinforced soil is made from two different materials (soil and reinforcement) that are reinforced by geogrid or geotextile, which are a group of geosynthetics. The reinforcement improves the mechanical properties of the soil by increasing the tensile strength and decreases the shear force transmitted by the soil. The main objective of this paper is to investigate the foundation settlement- elements settlement diagrams at the laboratory scale (using the physical model and PIV image (particle velocity) method) under loading. According to the results, it was observed that due to the tendency of loose soils to compression, the soil element's settlement compared to the foundation settlement is much less.

Due to the advantages of reinforced soil retaining walls, the using of type of the walls has increased in civil projects over the past three decades. One of the reinforced soil applications is the construction reinforced soil retaining walls. The major advantages of the reinforced soil walls are their flexibility and absorbency of deformations. Regarding experiences derived from previous studies, it attempted to investigate the effect of facing slope, oblique reinforcements and reinforcements anchoring on the performance retaining wall by experimental. In this study, 14 models of the walls were constructed. Results of the study provide evidence that horizontal deformation of the wall facing decreased with decreasing of the facing slope. Moreover, with increasing of the reinforcements slope the horizontal deformation reduced. Results showed that reinforced soil wall with oblique reinforcements of 10 degree and facing slope of 80 degree reduce the maximum horizontal deformation of the facing by 20%.Due to the advantages of reinforced soil retaining walls, the using of type of the walls has increased in civil projects over the past three decades. One of the reinforced soil applications is the construction reinforced soil retaining walls. Regarding experiences derived from previous studies, it attempted to investigate the effect of facing slope, oblique reinforcements and reinforcements anchoring on the performance retaining wall by experimental. In this study, 14 models of the walls were constructed. Results of the study provide evidence that horizontal deformation of the wall facing decreased with decreasing of the facing slope. Moreover, with increasing of the reinforcements slope the horizontal deformation reduced. Results showed that reinforced soil wall with oblique reinforcements of 10 degree and facing slope of 80 degree reduce the maximum horizontal deformation of the facing by 20%.Due to the advantages of reinforced soil retaining walls, the using of type of the walls has increased in civil projects over the past three decades. One of the reinforced soil applications is the construction reinforced soil retaining walls. The major advantages of the reinforced soil walls are their flexibility and absorbency of deformations. Regarding experiences derived from previous studies, it attempted to investigate the effect of facing slope, oblique reinforcements and reinforcements anchoring on the performance retaining wall by experimental. In this study, 14 models of the walls were constructed. Results of the study provide evidence that horizontal deformation of the wall facing decreased with decreasing of the facing slope.Due to the advantages of reinforced soil retaining walls, the using of type of the walls has increased in civil projects over the past three decades. One of the reinforced soil applications is the construction reinforced soil retaining walls. Results of the study provide evidence that horizontal deformation of the wall facing decreased with decreasing of the facing slope. Moreover, with increasing of the reinforcements slope the horizontal deformation reduced. Results showed that reinforced soil wall with oblique reinforcements of 10 degree and facing slope of 80 degree reduce the maximum horizontal deformation of the facing by 20%

The use of reinforced soil has been considered since long ago. Due to the improvement in technology¡ di erent kinds of reinforcement¡ including geosynthetic and steel types¡ have emerged. Geocells¡ as a special type of geosynthetic¡ have recently been used for soil improve- ment. Their three dimensional geometry causes extreme lateral con nement for in ll soil. This phenomenon leads to increased soil deformability and strength properties. The geocell reinforcement system is in the process of practical development due to its several advantages. Based on literature reviews in this eld¡ theories and design methods are far behind applications in the eld¡ especially roadway applications¡ due to a lack of under- standing of their mechanisms and in uencing factors. There are rather extensive laboratory studies in the eld of geocell reinforcement¡ but because of its complexity¡ numerical modeling of geocell reinforcement has rarely been performed and most numerical studies are based on equivalent composite models for representing the strength and sti ness of geocell con ned soil. In a com- posite model¡ the geocell reinforced soil is replaced with a soil with higher parameters. These parameters are se- lected based on limited test results performed on geocell reinforced soil. Therefore¡ generalizing them to other kinds of soil could be accompanied by further errors « In this numerical study¡ geocell and soil were simulated separately in 3D. Hence¡ this numerical modeling has no composite assumptions and errors. Also¡ all key behav- iors of the geocell were included completely. In this paper¡ geocell reinforced road embankments are simulated using the Finite Di erence Method (FDM) of FLAC3D. Geocell was simulated using geogrid struc- tural elements¡ and the elastic-perfectly plastic Mohr- Coulomb model was used for modeling the behavior of soil. In order to verify the modeling¡ results were com- pared with the results of a laboratory test¡ and¡ then¡ di erent factors in uencing reinforced embankment per- formance¡ including soil properties and the placement of geocell layers¡ were investigated.

improvement is essential. In cases where weak soil is improved by a replacing method, the improvement depth, due to the stress distribution pattern, is of great importance. However, in some cases, it is very dicult or too expensive to provide enough improvement depth. Hence, additional bearing capacity or other improvement methods are required. Using a geogrid to reinforce soil is an eective alternative way to improve the bearing capacity more eectively and economically. In this paper, the eect of replacing a loose layer by a dense one on the bearing capacity and settlement of a strip footing has initially been investigated. Then, the in uence of a geogrid layer placed on the interface of loose and dense layers is analyzed and investigated using nite dierence FLAC  software. The numerical model is veri ed and calibrated using experimental data from a physical model developed in the Soil Laboratory of Amirkabir University. Analyses results show that increasing the depth of compacted soil layer by more than  times the width of the foundation, does not have a considerable eect on the ultimate bearing capacity of strip footings, and only settlements will decrease. Using a geogrid layer between loose and compacted soil will improve the bearing capacity greatly, for a modi ed depth less than  times the width of the foundation 'The most ecient improvement in this method is when the geogrid layer is placed on the boundary of loose and dense layers at a depth of  the foundation width. The eciency of reinforcement is reduced by increasing the improvement depth. Using a reinforced layer with a width of less than  times the foundation width is not recommended.