• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.2
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• pp.93-103
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• 2004

In trench excavation, essential factor of earth-retaining temporary work structure should be easy taking to pieces and movement, and dead weight must be less. This paper studies about the light weight material and application as earth-retaining structure to prevent the slope failure of sand soil ground caused by the variation of groundwater level in trench excavation. That is, light weight earth-retaining structural is proposed and a simulation with FEM on application of proposed structural in sandy soil is presented. The results are summarized as follows; (1) The study proposed FRP H-shaped pannel for the light weight member, and also presented estimation method about stability. (2) Mechanical property (bending moment, shear force, axial force, displacement) were changed according to groundwater level, but these values had been within enough safety rate and allowable stress. Therefore, proposed light weight pannel with FRP is available for bracing structure in trench excavation.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.17.1-24
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• 1995

In tennelling lattice girders have basically the same function as steel arch supports. They serve as elements of temporary lining and in some cases also as part of the permanent lining. Also lattice girders are closely connected with that of the shotcreting lining technique. This paper presents the results of modelling test for analysing shorcrete rebound, shotcreting time and finding void spaces using the aretificial tunnel wall which consist of wood to evaluate the site applicability of lattice girders for tunnel support. Test results indicate that in case of using lattice girders as a tunnel support material, shotcrete rebound, shotcreting time and occurrence of void spaces are relatively reduced comparing to H-beam steel rib. And we can get some informations ths lattice girder has various advantages when we use it as one of tunnel support materials.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2017.11a
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• pp.343-344
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• 2017

우리나라는 산악지형 특성상 붕적층이 발달한 지역이 많아 도로나 건축물이 계획될 경우 일반적으로 이러한 지역을 배제하는 계획을 수립하게 된다. 그러나 현장 여건상 불가피하게 붕적층 구간을 포함한 건설 계획이 수립될 경우 지반 굴착, 사면 절취로 인해 지반 거동특성이 불안정할 수 있으므로 상세한 사전 조사와 적절한 토공 및 굴착 계획과 시공 중 Feed Back 등이 면밀히 이루어져야 한다. 붕적층 지반은 소량의 토사에 자갈, 호박돌, 전석 등이 혼재되어 있는 상태로 주로 테일러스에 의해 생성되며, 암괴의 함량이 매우 높으며 소량의 풍화된 잔류토사가 혼재된 양상을 보인다. 본 연구에서는 붕적층이 깊게 분포하는 지역, 특히 배면에 지장물(상수도관 등)문제로 인해 발생한 가시설 붕괴지역을 사례로 역해석을 통한 붕적층의 지반정수 재평가를 실시하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.4
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• pp.555-565
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• 2018

Nowadays, the artificial ground freezing (AGF) method has been used in many geotechnical engineering applications such as temporary excavation support, underpinning, and groundwater cutoff. The AGF method conducts the freezing process by employing a refrigerant circulating through a set of embedded freezing pipes to form frozen walls serving as an excavation support and cutoff wall. Two refrigerants of brine with the freezing temperature of $-20{\sim}-40^{\circ}C$ and liquid nitrogen with the freezing (evaporating) temperature of $-196^{\circ}C$ are commonly being used in geotechnical applications. This paper performed a series of field experiments to evaluate the freezing rate of marine clay in application of the AGF method. The field experiments consisted of the single freezing-pipe test and the frozen-wall formation test by circulating liquid nitrogen, which is a cryogenic refrigerant, into freezing pipes constructed at a depth of 3.2 m in the ground. The temperature of discharged liquid nitrogen was maintained through the automatic valve, and the temperature change induced by AGF method was measured at the freezing pipes and in the ground with time. According to the experimental results, the single freezing-pipe test consumed about 11.9 tons of liquid nitrogen for 3.5 days to form a cylindrical frozen body with the volume of about $2.12m^3$. In addition, the frozen-wall formation test used about 18 tons of liquid nitrogen for 4.1 days to form a frozen wall with the volume of about $7.04m^3$. The radial freezing rate decreased with increasing the radius of frozen body because the frozen area at a certain depth is proportional to the square of the radius. The radial freezing rate was formulated as a simple equation.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.573-581
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• 2008

In general, conventional sheeting H-pile is often used as a temporary member installed upon construction of outer retaining wall at basement floor. In CBW (composite basement wall), R/C basement wall is combined with H-Pile and resists lateral soil pressure together. This paper presents an experimental results of push out shear test of CBW with stud coupler as shear connectors to combine H-Pile with R/C wall six specimens with different diameter of FT (form tie) and arrangement of shear connectors were tested to evaluate the shear capacity of the composite wall. Test results showed that shear strength increased with diameter of FT. The shear strength of shear connector in CBW could be suitably predicted by using the previous equations codified in the codes. Best correlation, especially, was found when the calculation result by the formula in AISC 360-05 was compared to test one.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.20-27
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• 2014

In the construction site, various earth retaining systems are developed and applied to maintain stability of excavated area and structures. Among the methods, the underground continuous wall and the column-type diaphragm wall methods are especially used in construction site nearby buildings or roads. However, these methods have some disadvantages such as the difficulty of quality control and long curing time because these methods need to cast fresh concrete at the construction site. In addition, these methods are usually applied to the site for the temporary purpose. In this paper, we suggest precast hollow prestressed concrete pile for continuous pile wall system. To investigate the structural behavior of suggested pile, which is the main member of the suggested system, tests pertaining to the structural behavior and prestressing force applied in the pile are conducted. From the test results, it was found that the prestressing force measured is sufficient compared with the value obtained by the design equation and the cracking moment measured is 34% higher than the design value. In addition to the above, this precast hollow prestressed concrete pile has an additional safety margin that the maximum moment is 59.2% higher than the cracking moment which is one of the serviceability limits for the design of the system.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.2
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• pp.175-187
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• 2015

In this paper, the development of trench shield machine for near-surface railway construction were presented. The Near-surface railway can be constructed by cut and cover construction method, because it is installed at the depth of 5~7 m below roads. The cut and cover construction method mostly use temporary supports. The limitation of the cut and cover method is high installation cost and long construction period. To overcome these disadvantages, development of the trench shield machine is proposed and expected to shorten the construction time and cost of near-surface railway system. The sliding retaining wall of trench shield equipment replaces the role of temporary support (solider piles and lagging) and excavator equiped to the bottom front of the machine shorten the excavation time. This paper deals with design of the bit attached to the excavator and required capacity of the motor.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.5-15
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• 2023

The evaluation of passive earth pressure plays a crucial role in the design of earth-retaining structures such as retaining walls and temporary earth-retaining walls to withstand horizontal earth pressure. In the earth pressure theory, active and passive earth pressures represent the earth pressures at the limit state, where the wall displacement reaches the maximum allowed displacement. In the design of earth-retaining structures, the passive earth pressure is considered as the resisting force. In this context, the limit displacement at which passive earth pressure occurs is significantly greater than that associated with the active earth pressure. Therefore, it is irrational to apply this displacement directly to the calculation of passive earth pressure. Instead, it is necessary to consider the mobilized passive earth pressure exerted at the allowable horizontal displacement to evaluate the structural stability. This study proposes an allowable wall displacement, denoted as 0.002 H (where H represents the excavation depth), based on a literature review that focuses on sandy soils. To calculate the mobilized passive earth pressure from the wall displacement, a semi-empirical equation is proposed. By analyzing the obtained data on mobilized passive earth pressure, a reduction factor applicable to Rankine's passive earth pressure is proposed for practical application in sandy soils under different wall movement types.

• Journal of the Korean GEO-environmental Society
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• v.5 no.3
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• pp.51-60
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• 2004

In Korea there are recently many attempts to expand a temporary soil nailing system into a permanent soil nailing system since the first construction in 1993. In the soil nailing system, the rigid facing walls act on restraining the deformation of the ground. These are purposed to minimize the damage of adjacent buildings or underground structures. In Korea, to minimize the relaxation of the ground, the soil nailing system in the downtown area is often used experientially together with braced cuts, sheet pile walls, soil cement walls (SCW), or jet grouting walls. However, for the conservative design, the confining effects by the stiff facing have been ignored because the proper design approach of considering the facing stiffness has not been proposed. In this study, various laboratory model tests are carried out to examining the influence the rigidity of facings on the global safety of soil nailing system. Also, the parametric studies using the numerical technique as shear-strength reduction technique are carried out. In the parametric study, the thickness of concrete facing walls is changed to identify the effects of the facing wall stiffness.

• Journal of the Korean Geotechnical Society
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• v.18 no.3
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• pp.33-41
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• 2002

Soil nailing type of retaining structures has been widely used in Korea far the purpose of the temporary and permanent support in excavations and slope stability. The important factors in application of soil nailing systems in urban excavation site nearby the existing structures are the displacement of the wall and tensile farce of the nails, etc. In this paper, the fled back analyses are carried out at 11 excavation sites to investigate the behavior of tensile farce of nails at stepwise excavation in the multi-layered strata including various rock layers. The results of the fled back analysis are less than about 50% of the measured ones. The distance of active zone by measurements are shown almost larger than that of fled back analysis when the distance of active Bone is defined from the surface of wall to the potential failure surface. And the results of fled back analysis are within the range proposed by the project CLOUTERRE and Cartier & Gigan (1983) which were 0.3$H_f$, and 0.5$H_f$, of the final excavation depth ($H_f$,) respectively, but the values of the measurement were larger than these values.