• Journal of the Korean Geotechnical Society
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• v.25 no.1
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• pp.41-54
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• 2009

The purpose of this research is to introduce the new temporary earth retaining wall system using landslide stabilizing piles. This system is a self-supported retaining wall (SSR) without installing supports such as tiebacks, struts and rakers. The SSR is a kind of gravity structures consisting of twin parallel lines of piles driven below excavation level, tied together at head of soldier piles and landslide stabilizing piles by beams. In order to investigate applicability and safety of this system, a series of experimental model tests were carried out and the obtained results are presented and discussed. Furthermore, the measured data from seven different sites on which the SSR was used for excavation were collected and analyzed to investigate the characteristic behavior lateral wall movements associated with urban excavations in Korea. It is observed that lateral wall movements obtained from the experimental model is in good agreement with the general trend observed by in site measurements.

• Geotechnical Engineering
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• v.7 no.4
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• pp.75-88
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• 1991

A lot of landslides has occurred in rainy seasons beginning at June through September in Korea, where about 70 percent of the total area is mountaneous. Piles can be used as one of the most useful methods to stabilize such landslides. When a row of piles is installed in soil undergoing lateral movement such as landslides, the soil across the open space between the piles can be retained by the arching action of the soil. For the purpose to establish a reasonable design method for stabilizing piles, a method for stability analysis of the slope containing stabilizing piles is presented, using the theoretical equation of the lateral force acting on the piles in soil undergoing lateral movement. In particular, the theoretical equation is arranged by applying the coefcients of lateral force as a simple equation. And also the differential equations proposed in the previous studies for the pile-stability analysis are modified, assumming that the piles above the sliding surface shall be subjected to the lateral reaction from soil in proportion to the pile deflection. Finally, to investigate the effect of stabilizing piles against landslides, an existing landslide slope in Korea is adopted as an example.

• Journal of the Korean Geotechnical Society
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• v.32 no.7
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• pp.47-56
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• 2016

In the case of excavating ground backfilled with soft ground, ground destruction occurs owing to the discharge of groundwater from excavated back ground in spite of earth retaining wall. To minimize this, indoor model test was implemented applying stabilizing pile as a solution for ground destruction. The unreinforced case was compared with the reinforced case and the comparison demonstrated that the ratio of the gap in settlement of the two cases is about three to one, which proves the reinforcement effect (Kim, 2014). This study has carried out the evaluation of appropriate pile spacing ratio, according to the confirmed effect of stabilizing pile. In the evaluation test the case with pile spacing ratio of 0.66 (5 stabilizing piles) was compared with that of 0.76 (3 stabilizing piles), and it has been shown that applying stabilizing pile has effect on ground destruction reduction, but may rather work as load when pile spacing ratio is narrower than a certain interval. So it was found that adjustment for appropriate pile spacing ratio is required at the stage of design. This study has shown that the pile spacing ratio is appropriate at around 0.7~0.8, which reduces ground destruction and does not function as the load of excavated back ground.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.157-170
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• 1999

A new design technique is presented to stabilize cut slopes in cohesive soils by use of piles. The design method can consider systematically factors such as the gradient and height of slope, the number and position of pile's rows, the interval and stiffness of piles, etc. The design method is established on the basis of the stability analysis of slope with rows of piles. The basic concept applied in the stability analysis is that the soil across the open space between piles can be retained by the arching action of the soil, when a row of piles is installed in soil undergoing lateral movement such as landslides. To obtain the whole stability of slope containing piles, two kinds of analyses for the pile-stability and the slope- stability must be performed simultaneously. An instrumentation system has been installed at a cut slope in cohesive soil, which has been designed according to the presented design process. The behavior of both the piles and the soil across the open space between piles is observed precisely. The result of instrumentation shows that the cut slope has been stabilized by the contribution of stabilizing effect of piles on the slope stability in cohesive soil.

• Geotechnical Engineering
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• v.12 no.1
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• pp.35-46
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• 1996

An instrumentation system is designed to observe the behavior of slope soil and stabilizing piles during heavy rains. Inclinometers, standpipe piezometers and strain gages are installed into a cut slope reinforced by a row .of piles for an apartment. The horizontal deflection and bending stress developed on the piles can be measured, respectively, by the inclinometers and strain gages installed in piles, while the horizontal deformation of the slope soil can be measured by the inclinometer installed in the soil across the open space between piles. The groundwater level doss not grow so sensitively during heavy rain. The behavior of piles and slope is 서footed by the wetting front, since the driving force of slope increases with the weight of slope soil above the wetting front. The stabilizing piles and the slope soil show elastic behavior during heavy rain.

• The Journal of Engineering Geology
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• v.16 no.2 s.48
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• pp.189-199
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• 2006

This paper presents a field study of the stability of slope collapsed during road construction and proposes a reasonable countermeasure if the current slope is unstable. As a result of slope investigation, it was found that the slope includes five tension cracks and the sliding surface is started from the tension crack and propagated the surface soil layer through weathered rock layer. The slope stability analyses are conducted in case of dry and rainfall seasons. The results indicate that the slope is unstable status. A reinforcement method of slope failure should be selected according to the scale of failure. That is, the scale of slope failure, which is classified small, middle and large size determines the reinforcement method of slope. Since the slope interested in this study is large size failure slope, the reinforcement method to control slope failure is selected stabilizing piles, and seed spray and drainage of surface waterare also selected to remain the factor of safety. The SLOPILE (Ver. 3.0) program is applied in order to do stability analysis of slope reinforced by piles. As the result of analysis, the slope reinforced by a row of piles shows the stable state. It is clearly confirmed that the stabilizing of piles can improve the stability of slope.

• Journal of the Korean Geotechnical Society
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• v.17 no.6
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• pp.5-14
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• 2001

This paper describes a simplified design method of stabilizing piles based on an experimental tests and an analytical study which can take into account the safety factor of slope and pile spacing. The nonlinear characteristics of the soil-pile interaction for stabilizing piles are modeled by using load transfer method. The interaction factors due to pile spacing and cap rigidity were estimated by using a three dimensional nonlinear finite element approach and laboratory tests. Based on the results obtained, the interaction factors are proposed quantitatively for one-row pile groups with spacing-to-diameter ratios varying far 2.5 to 7.0. The Bishop's simplified method of slope stability analysis is extended to incorporate the soil-pile interaction and determine the safety factor of the reinforced slope. Through the comparative study, it is found that the prediction by present approach is in relatively good agreement with the results of centrifuge tests and field tests and three dimensional finite element analyses.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.2
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• pp.93-101
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• 2011

Korea has about 70% of its land classified as the mountain area, which has led to cut-slope being the result of substantial road and railway construction. However, there is currently a lack of research about the seismic retrofit design of a slope, even though many earthquakes have recently occurred at home and abroad. In this study, in order to investigate the stabilizing effect of piles against sliding during an earthquake, a series of 1 g shaking table tests and pseudo-static analyses were carried out. As a result, the stabilizing effect of piles against sliding during an earthquake was verified by the 1 g shaking table tests and the most effective result from the pseudo-static analyses was that the installation of the piles on the central part of the slope, where the failure surface included piles unlike the lower part and upper part of the slope. Furthermore, when the pile was installed on the central part of the slope, the change of the safety factor depending on the distance between the center of two piles was evaluated.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.5-16
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• 2008

Field monitoring data of nine sites were investigated to suggest an evaluation method on lateral movement of the quaywall on soft grounds. It was found that in order to evaluate the lateral movement of quaywalls with foundation piles such as the landing pier, the safety factor of slope should be applied with consideration of the stabilizing effect of the piles. If the required safety factor of slope is greater than 1.6 in slope stability analysis with consideration of the stabilizing effect of the piles, the quaywalls are considered to be safe against lateral movement. On the other hand, for the gravity-type quaywalls such as the caisson type quaywall, the required safety factor of slope should be greater than 1.3.

• Geomechanics and Engineering
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• v.23 no.5
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• pp.481-491
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• 2020

Piles installed in row(s) are used as an effective technique to improve the stability of soil slopes. The analysis of pile-stabilized slopes require a reliable prediction of lateral resistance offered by the piles. In this work, an analytical solution is developed to estimate the lateral resistance offered by the stabilizing piles in sand and c - 𝜙 soil slopes considering soil arching phenomenon. The soil arching in both horizontal direction (between the neighboring piles) and vertical direction (in the active wedge in front of the pile row) are studied and their effects are incorporated in the proposed model. The shape of soil arch is assumed to be circular and principal stress trajectories are defined separately for both modes of arching. Experimental and numerical studies found in literature were used to validate the proposed method. A detailed parametric analysis was performed to study the influence of pile diameter, center-to-center spacing, slope angle and angle of internal friction on the lateral pile resistance.