• Magazine of the Korean Society of Agricultural Engineers
• /
• v.38 no.5
• /
• pp.140-154
• /
• 1996

In this study, displacement, deformation, and stability according to change of cohesion and internal friction angle were investigated through elasto-plastic method, finite-element method, and in-site experiment when excavating soft ground using sheet pile. The results of the study were as follows : 1. The horizontal displacement was 5.5% of the excavation depth by the elasto-plastic method and 3.9% of the excavation depth by the on-site experiment at the final excavation depth(GL-8.Om) on the condition of double stair strut after excavating GL-6.Om. 2. Relationships between cohesion(c) and internal friction angle $({\varphi})$ when safety factor to the penetration depth was 1.2 is shown in the following equations : (a) c= -O.0086$({\varphi})$+ O.3(D=3m) and (b) c=-0.00933$({\varphi})$+0.14(D=4m). 3. The results of elasto-plastic method and the experiment show that possible excavation depth was GL-6.Om after setting single stair strut in a short period in terms of possibility of carrying out on the condition of experimental site on the contrary general reinforcement method, setting double stair strut after excavating GL-4.0m. 4. After setting the strut, distribution of the horizontal displacement had concentrated on the excavation base and possible local failure which the shear strain caused decreased by the strut reinforced. 5. After setting strut, displacement of sheet pile was decreased by half, the limit of stable excavation depth of ground was GL-8.Om, and the maximum horizontal displacement at the GL-8.Om was 1.6% of excavation depth by the elasto-plastic method, 0.7% of excavation depth by the finite-element method.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.1032-1037
• /
• 2006

This thesis studied effects of the excavation around railroads on the deformation of the lateral ground and neighboring railroads. The conclusions of the study are as follows. 1. When the depth of excavationis 10m, the influential area should be 35m for soft clay, 20m for normal clay, 15m for hard clay, 15m for loose sand, 12m for slightly dense sand, and 8m for dense sand. 2. When the influential area is 10m, the allowable excavation depth should be 2.5m for soft clay, 4.8m for normal clay, 7.5m for hard clay, 7.2m for loose sand, 8.8m for slightly dense sand, and 10m for dense sand. 3. When the influential area is 20m, the allowable excavation depth should be 4.5m for soft clay, and up to 10m for the other five kinds of soil. 4. When the influential area is 30m, the allowable excavation depth should be 7.5m for soft clay, and up to 10m for the other five kinds of soil. 5. When the influential area is 35m, the allowable excavation depth should be up to 10m for all kinds of soil.

• Korean Journal of Agricultural Science
• /
• v.24 no.2
• /
• pp.226-236
• /
• 1997

The results obtained by elasto-plastic analysis method about the displacement, deformation and stability on the soft ground excavation using sheet pile were summarized as follows ; 1. In the case of strut 1 step, the maximum wall displacement value in the first and the second excavation was small, but it increase remarkably after the third excavation and when the excavation depth was 8m, the point of maximum wall displacement was shown 0.75H~0.8H. 2. The value of safety factor(Fs) was increased with increasing of the penetration depth of sheet pile, cohesion and internal friction angle of ground. Safety factor was mostly effected by penetration depth of sheet pile and more effected by cohesion than internal friction angle of ground. 3. Since the deformation of sheet pile of this ground from the results of analysis and measurement increased remarkabaly after 6m excavation depth, it was desirable that the point of strut installation was GL-6m. 4. Safe excavation depth on ground by analysis considered penetration depth, cohesion and internal friction was shown at the table 3.

• Journal of the Korean Geotechnical Society
• /
• v.15 no.6
• /
• pp.71-86
• /
• 1999

The displacements of soil nailed wall and the nail tensile force for 11 soil nailing sites were investigated by using measurements obtained from inclinometer and strain gauge. The maximum horizontal displacement which occurred between 5% and 15% of the final excavation depth was found to be below 0.3% and 0.2% of excavation depth for well and poorly constructed sites. It was also found that the maximum horizontal displacements for 0.4%, 0.3% and 0.2% of excavation depth occurred when the ratios of nail length to final excavation depth were 0.5, 0.5~0.6 and 0.6~0.7. But the maximum horizontal displacement increased by 0.3% of excavation depth when the ratio was above 0.7. This was probably due to the shallow excavation depth and the deep soil stratum. The non-dimensional maximum tensile force of nail, K, from ground surface to $(0.6H_f)$ of the final excavation depth was less than 0.8 and decreased linearly between $(0.6H_f)$ and the final excavation depth. Also, the maximum tensile force was found to reach up to 60% of the ultimate tensile force at final excavation.

• Journal of the Korean Geotechnical Society
• /
• v.36 no.12
• /
• pp.57-68
• /
• 2020

In the case of two-dimensional analysis generally applied in the analysis of Earth Retaining Wall, mutual interference occurs due to earth pressure, when the excavation width is small, and in the section where the excavation width is small, and the resulting influence makes it difficult to secure reliability in the horizontal displacement of the retaining wall when performing 2-dimensional analysis in a section with a small excavation width. This study performed two-dimensional and three-dimensional finite element analyses on excavation depth (H) and excavation width (B) under various conditions for the H-pile earth wall, in the geological conditions of clayey soil, sandy soil, and weathered rock, and examined the relationship between excavation width and horizontal displacement according to each condition, to identify the boundary of the excavation width, which is the range of mutual interference caused by earth pressure. As a result, it was possible to clearly distinguish the analytical boundary according to the excavation width only in the clayey soils with relatively large horizontal displacement. It is concluded that it is reasonable to perform a 3D finite element analysis, which is similar to the actual behavior, if the excavation scale (B/H) is 2.0 or less, with the digging width less than 12 m at a digging depth of 10 m or less, and with the the one less than 24 m at a digging depth of 10 m or more, and that 2-dimensional finite element analysis may be used in cases where the excavation width is greater than 12 m when the excavation scale (B/H) is 2.0 or more and the excavation depth is 10 m or less, and the excavation width is greater than 24 m at an excavation depth of 10 m or more.

• Journal of the Korean Society of Safety
• /
• v.23 no.1
• /
• pp.28-34
• /
• 2008

The corrugated steel plate structures is applied to the construction of mountain tunnel portal part with shallow depth, the tunnel on the outskirts of urban areas and ecology move passage. In this study, A finite element method is used for research the behavior of corrugated steel plate structures due to construction position under declinating earth pressure and excavation depth. A finite element method were performed varying construction position(10, 15, 20 and 25m) from slope and excavation depth from surface. The hoop thrust and moment, displacement of corrugated steel plate subjected to construction position and excavation depth is determined from a finite element method. From results of finite element method, it was found that the increase of thrust and the decrease of displacement as the amount of distance increase from slope with construction position. But the thrust and moment, displacement has not different value with excavation depth.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.2
• /
• pp.43-52
• /
• 2014

This paper examined the effect of step-wise excavation depth on the earth pressure against an excavation wall in rock mass. Numerical parametric studies were conducted based on the Discrete Element Method (DEM) to carry out the problems in rock mass. Controlled parameters included step-wise excavation depth, rock types, and joint conditions (joint shear strength and joint inclination angle). The magnitude and distribution characteristics of the induced earth pressure in a jointed rock mass were investigated and compared with Peck's earth pressure for soil ground. The results showed that the earth pressure against an excavation wall in rock mass were highly affected by different rock and joint conditions, and the effect of step-wise excavation depth increased as a rock type is deteriorated more. In addition, it was found that the earth pressure against an excavation wall in rock mass might be considerably different from Peck's empirical earth pressure for soil ground.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.12 no.5
• /
• pp.116-124
• /
• 2008

In order to evaluate the behavior patterns of the ring beam by excavation at the vertical wall with circular section, the measured field datum were analyzed and evaluated in this study. Additionally, stress patterns of the ring beam with the change of excavation depth were estimated by using FE analysis. As the results, it was shown that the tendency of the measured values for the behavior patterns of the ring beam is similar to the analyzed values in FE analysis. From the tendency, it was confirmed that the behaviors of the ring beam due to change of excavation depth can predict by FE analysis using the suggested method in this study.

• Geomechanics and Engineering
• /
• v.24 no.4
• /
• pp.323-335
• /
• 2021

This paper aims to estimate the range of the excavation damaged zone (EDZ) formation caused by the tunnel boring machine (TBM) advancement through dynamic three-dimensional large deformation finite element analysis. Large deformation analysis based on Coupled Eulerian-Lagrangian (CEL) analysis is used to accurately simulate the behavior during TBM excavation. The analysis model is verified based on numerous test results reported in the literature. The range of the formed EDZ will be suggested as a boundary under various conditions - different tunnel diameter, tunnel depth, and rock type. Moreover, evaluation of the integrity of the tunnel structure during excavation has been carried out. Based on the numerical results, the apparent boundary of the EDZ is shown to within the range of 0.7D (D: tunnel diameter) around the excavation surface. Through series of numerical computation, it is clear that for the rock of with higher rock mass rating (RMR) grade (close to 1st grade), the EDZ around the tunnel tends to increase. The size of the EDZ is found to be direct proportional to the tunnel diameter, whereas the depth of the tunnel is inversely proportional to the magnitude of the EDZ. However, the relationship between the formation of the EDZ and the stability of the tunnel was not found to be consistent. In case where the TBM excavation is carried out in hard rock or rock under high confinement (excavation under greater depth), large range of the EDZ may be formed, but less strain occurs along the excavation surface during excavation and is found to be more stable.

• The Journal of the Acoustical Society of Korea
• /
• v.38 no.2
• /
• pp.161-167
• /
• 2019

In this paper, the performance verification of an around-view sonar and an excavation depth measuring sonar applicable to track-based ROVs (Remotely Operated underwater Vehicles) for heavy duty work is studied. For the performance verification, an experiment is carried out in a water tank and at sea by attaching the around-view sonar and the excavation depth measuring sonar for a heavy work ROV. In the case of the around-view sonar, image sonars are mounted on ROV in four directions (front, back, left and right) and in the case of the excavation depth measuring sonar, the same kind of MBES (Multi Beam Echo Sounder) is mounted on the front of the ROV. The result of an operation test of the ROV equipped with these sonars shows that the sonar systems are rarely affected by high turbidity due to sedimentation during the operation. In the case of the around-view sonar, it is possible to see rock formation, gravel and sandbank 30 m ahead of the ROV. It is confirmed that the excavation depth can be measured after the ROV has performed the excavation. This experiment demonstrates that the ROV can improve the efficiency of the work by utilizing the around-view sonar and the excavation depth measuring sonar.