• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.09b
• /
• pp.152-160
• /
• 2010

In this study, cohesion of soft ground, soft ground depth and embankment height varying conditions, such as the impact of each condition after the calculation of the range, SCP was performed to evaluate the applicability of the method. Reinforcing effects of scope, and permit lateral movement of SCP 2D and 3D analysis of the program were calculated by the displacement ratio, the result follows. The height and depth of soft soil embankment with increasing and decreasing the cohesion tends to be affected were long range, SCP method applied by the finite element analysis Cu = 1.0tf/$m^2$, embankment height is 3.0m depth of soft soil can be applied in a less than 5.0m, and Cu = 3.0tf/$m^2$, embankment height, the soft soil depth is 3.0m 12.0m, Cu = 3.0tf/$m^2$, embankment height is 5.0m less than 7.0m depth of soft soil can be applied in was. And Cu = 5.0tf/$m^2$, embankment height is 3.0m below 15.0m depth rouge anti Floor, Cu = 3.0tf/$m^2$, embankment height of 5.0m 12.0m depth below the soft soil, Cu = 5.0tf/$m^2$, If the depth of soft soil embankment height of 7.0m and below 5.0m was applicable.

• Geomechanics and Engineering
• /
• v.6 no.1
• /
• pp.17-31
• /
• 2014

This paper investigates the development of failure surfaces induced by an embankment on soft marine clay deposits and the characteristics of such surfaces through numerical simulations and its comparative study with monitoring results. It is well known that the factor of safety of embankment slopes is closely related to the vertical loading, including the height of the embankment. That is, an increase in the embankment height reduces the factor of safety. However, few studies have examined the relationship between the lateral movement of soft soil beneath the embankment and the factor of safety. In addition, no study has investigated the distribution of the pore pressure coefficient B value along the failure surface. This paper conducts a continuum analysis using finite difference methods to characterize the development of failure surfaces during embankment construction on soft marine clay deposits. The results of the continuum analysis for failure surfaces, stress, displacement, and the factor of safety can be used for the management of embankment construction. In failure mechanism, it has been validated that a large shear displacement causes change of stress and pore pressure along the failure surface. In addition, the pore pressure coefficient B value decreases along the failure surface as the embankment height increases. This means that the rate of change in stress is higher than that in pore pressure.

• Structural Engineering and Mechanics
• /
• v.56 no.4
• /
• pp.507-534
• /
• 2015

The present work investigates the behavior of the embankment models resting on soft soil reinforced with ordinary and stone columns encased with geogrid. Model tests were performed with different spacing distances between stone columns and two lengths to diameter ratios (L/d) of the stone columns, in addition to different embankment heights. A total number of 42 model tests were carried out on a soil with undrianed shear strength $${\sim_\sim}10kPa$$. The models consist of stone columns embankment at s/d equal to 2.5, 3 and 4 with L/d ratio equal 5 and 8. Three embankment heights; 200 mm, 250 mm and 300 mm were tested for both tests of ordinary (OSC) and geogrid encased stone columns (ESC). Three earth pressure cells were used to measure directly the vertical effective stress on column at the top of the middle stone column under the center line of embankment and on the edge stone column for all models while the third cell was placed at the base of embankment between two columns to measure the vertical effective stress in soft soil directly. The performance of stone columns embankments relies upon the ability of the granular embankment material to arch over the 'gaps' between the stone columns spacing. The results showed that the ratio of the embankment height to the clear spacing between columns (h/s-d) is a key parameter. It is found that (h/s-d)<1.2 and 1.4 for OSC and ESC, respectively; (h is the embankment height, s is the spacing between columns and d is the diameter of stone columns), no effect of arching is pronounced, the settlement at the surface of the embankment is very large, and the stress acting on the subsoil is virtually unmodified from the nominal overburden stress. When $(h/s-d){\geq}2.2$ for OSC and ESC respectively, full arching will occur and minimum stress on subsoil between stone columns will act, so the range of critical embankment height will be 1.2 (h/sd) to 2.2 (h/s-d) for both OSC and ESC models.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.1
• /
• pp.37-45
• /
• 2021

The construction of the tunnel portal should be careful because cover depth is shallow and it is difficult to exhibit the arching effect. Tunnel stability may be reduced with additional embankment above the portal of tunnel. In this study, in order to examine the stability of the tunnel according to additional embankment above the portal of tunnel, numerical analysis was performed while changing the ground conditions and height of embankment. As a result of the numerical analysis, it was found that the allowable flexural compressive stress of shotcrete and allowable axial force of rockbolts were exceeded when the height of additional embankment was 12 m in rock mass rating V. When considering the displacement, the range of the plastic region and the behavior of the support materials, the tunnel stability seems to be greatly reduced if the height of additional embankment above the portal of tunnel exceeds 10 m.

• Journal of the Korean Geotechnical Society
• /
• v.32 no.6
• /
• pp.5-16
• /
• 2016

In the geosynthetics-reinforced piled embankment the effects of soft soil stiffness, friction angle of the fill material, tensile stiffness of geosynthetics, and height of the embankment on the load transfer soil arch measured by the critical height were numerically investigated. Results from parametric studies show that the magnitude of the soft soil stiffness is the most influencing factor on the critical height. The contour charts of the critical height with respect to the combination of the soft soil stiffness and other parameters were presented. The charts show that the critical height sensitively varies with the combination of the soft soil stiffness and the height of embankment. Under the sufficiently low stiffness of soft soil, the critical height sensitively varies with the friction angle of the fill material. Once the geosynthetic layer is placed, however, the magnitude of the tensile stiffness of the geosynthetic layer hardly influences the critical height of the soil arch.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.4
• /
• pp.171-181
• /
• 2000

A series of model tests were performed both to investigate the load transfer by soil acrching in fills above embankment pils and to verify of the theoretical analysis. In the model tests, the piles were installed in a row below the embankment and the cap beams were placed on the pile heads perpendicular to the longitudinal axias of the embankment. The space between pile cap beams and the embankment height was focused as the major factors affecting the load transfer in embankment fill. When the embankment fill was higher than the minimum required height, which was about 33% higher than the radius of the soil arch proposed by theoretical discussion in the previous study, not only the soil arching could be developed completely but also the experimental results showed good agreement with theoretical predictions. The portion of the embankment load carried by model pile cap beams decreased with increment of the space between pile cap beams, while it increased with increment of the embankment height. Therefore, to maximize the effect of embankment load transfer by piles on design, the interval ratio of pile cap beams should be decreased under considerably high embankments by reducing the space between cap beams and/or enlarging the width of pile cap beams.

• Journal of the Korean Geosynthetics Society
• /
• v.9 no.3
• /
• pp.9-18
• /
• 2010

A series of model tests were performed to investigate the load transfer by soil arching in geosynthetic-reinforced and pile-supported(GRPS) embankment systems. In the model tests, model piles with isolated cap were inserted in the model container and geosynthetics was laid on the pile caps below sand fills. The settlement of soft ground was simulated by rubber form. The loads acting on pile caps and the tensile strain of geosynthetics were monitored by data logging system. At the given interval ratio of pile caps, the efficiency in GRPS embankment systems increased with increasing the height of embankment fills, then gradually converged at constant value. Also, at the given height of embankment fills, the efficiency decreased with increasing the pile spacing. The embankment loads transferred on pile cap by soil arching increased when the geosynthetics installed with piles. This illustrated that reinforcing with the geosynthetics have a good effect to restraint the movement of surrounding soft grounds. The load transfer in GRPS embankment systems was affected by the interval ratio, height of fills, properties of grounds and tensile stiffness and so on.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.2C
• /
• pp.133-141
• /
• 2008

Theoretical analysis are developed to estimate the load transfer by soil arching in geosynthetic-reinforced and pile-supported(GRPS) embankment systems. According to the results of analyses, the efficiency of embankment pile systems increases when the geosynthetics are installed with piles. Especially the increment of efficiency is more remarkable in the low embankment height, where soil arching can not be fully developed. The factors affecting the load transfer in GRPS embankment systems are the pile spacing, the height and properties of embankments, and the strength of geosynthetics. The efficiency decreases with increasing the pile spacing, while it increases with the height and internal friction angle of embankment fills, and the strength of geosynthetics. These results of analyses show the proposed analysis method is resonable to estimate the soil arching in GRPS embankment systems.

• Structural Engineering and Mechanics
• /
• v.61 no.6
• /
• pp.775-784
• /
• 2017

This study is devoted to developing many new substructure models for ballasted railway track by using the pyramid model philosophy. As the effect of railway embankment has been less considered in the previous studies in the field of vehicle/track interaction, so the present study develops the pyramid models in the presence of railway embankment and implements them in vehicle/track interaction dynamic analyses. Considering a moving car body as multi bodies with 10 degrees of freedom and the ballasted track including rail, sleeper, ballast, subgrade and embankment, two categories of numerical analyses are performed by considering the new substructure systems including type A (initiation of stress overlap areas in adjacent sleepers from the ballast layer) or type B (initiation of stress overlap areas in adjacent sleepers from the subgrade layer). A comprehensive sensitivity analyses are performed on effective parameters such as ballast height, sleepers spacing and sleeper width. The results indicate that the stiffness of subgrade, embankment and foundation increased by increasing the ballast height. Also, by increasing the ballast height, rail and ballast vertical displacement decreased.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.57 no.1
• /
• pp.99-109
• /
• 2015

In the construction industry, the interest for recycling aggregates is rising as more people demand for alternatives due to lack of supply of natural aggregates and environmental problems. However, in order for recycled aggregates to be used in infrastructures, stability and other factors need to be verified. Therefore, the objective of this study is to analyze the sensitivity of soil properties to secure slope safety according to various heights of embankment when bottom ash and dredged soil mixture is applied in the embankment. In most cases, all heights were safe for the slide for the embankment whether the water level is full or sudden draw down. The result of the sensitivity analysis revealed that the unit weight of embankments is highest among all factors to be considered. However, the sensitivity of the unit weight became smaller and the sensitivity of the friction angle of embankments increased with the height of embankments. The sensitivity of factors of core materials is very small because the core has weaker physical properties than those of the embankment. The effect of the height for each factor is different for each slope and water levels. The sensitivity of the unit weight of embankments is most affected when the height is 60m in the upstream slope. To conclude, bottom ash and dredged soil mixture can be applied in the embankment and different factors must be considered in different scale because the sensitivity depends highly on the height of embankments.