• Geomechanics and Engineering
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• 제15권3호
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• pp.823-831
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• 2018

The most important issue during shield TBM tunneling in soft ground formations is to appropriately control ground surface settlement. Among various operational conditions in shield TBM tunneling, the face pressure and backfill pressure should be the most important and immediate measure to restrain surface settlement during excavation. In this paper, a 3-D hydro-mechanical coupled FE model is developed to numerically simulate the entire process of shield TBM tunneling, which is verified by comparing with real field measurements of ground surface settlement. The effect of permeability and stiffness of ground formations on tunneling-induced surface settlement was discussed in the parametric study. An increase in the face pressure and backfill pressure does not always lead to a decrease in surface settlement, but there are the critical face pressure and backfill pressure. In addition, considering the relatively low permeability of ground formations, the surface settlement consists of two parts, i.e., immediate settlement and consolidation settlement, which shows a distinct settlement behavior to each other.

• Geomechanics and Engineering
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• 제39권3호
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• pp.227-240
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• 2024

This study investigates the control effect of isolation piles on ground settlement resulting from foundation pit excavation. Based on the three-stage analysis method, first, the Kerr three-parameter foundation model is introduced, and the deflection differential equation is derived to solve the horizontal displacement of the diaphragm wall. Then, based on the horizontal displacement of the diaphragm wall, the boundary element method is used to calculate the additional stress at the boundary of the foundation pit, and the horizontal additional displacement and additional stress of the soil free field at the position of the isolation pile are obtained using the Mindlin solution. Subsequently, soil free field additional stress is applied to the pile foundation, and the shielding effect of group piles is also considered. Based on the Kerr three-parameter foundation model, the deflection differential equation of the pile foundation under the influence of horizontally oriented additional stress is established to solve the horizontal displacement of the isolated piles. Finally, the boundary element method is used again to invert the additional stress caused by the horizontal displacement of the isolation pile, and the surface settlement after the isolation pile is calculated in combination with the Mindlin vertical displacement solution. The spatial finite element model is established and compared with the theoretical calculation results to prove the rationality of the theory. The influence of basic construction parameters is analyzed theoretically, and it is found that the surface settlement is reduced by 30.9% compared with no isolation pile. Of the selected parameters in this paper, the effects of the isolation pile's controlled diameter, spacing, and elastic modulus, the thickness and elastic modulus of the diaphragm wall on the surface settlement are 4.9 mm, 3.1 mm, 3.3 mm, 3 mm, 1.7 mm, respectively, which are 45.4%, 28.7%, 30.6%, 27.8%, 15.7% of the standard working conditions, respectively. This shows that optimization of the isolation pile parameters has the best effect on surface settlement, optimization of the diaphragm wall parameters has the poor effect.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1990년도 PROCEEDINGS OF THE FIRST KOREA-JAPAN JOINT GEOTECHNICAL SEMINAR ON EXCAVATION and TUNNELING IN URBAN AREAS
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• pp.9-24
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• 1990

Most tunnels in soft soils in urban areas are constructed by shield tunnelling method for environmental reasons. Ground surface settlements are caused by shield tunnelling so that auxiliary measures are often required. Simple methods to predict ground surface settlement are given. The use of the slurry or the earth pressure balance shield machine and the application of new methods of grouting with computer aided operation control systems decreases the ground surface settlement to 3 mm. The construction cost of tunnels is almost identical whichever type of shield machine is employed according to a statistical investigation.

• Geomechanics and Engineering
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• 제15권2호
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• pp.769-774
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• 2018

The growth of cities requires the construction of new tunnels close to the existing ones. Prediction and control of ground movement around the tunnel are important especially in urban area. The ground respond due to EPB (Earth Pressure Balance) pressure are investigated using the finite element method by ABAQUS in intersection of the triplet tunnels (Line 2, 3 and 4) of Mashhad Urban Railway in Iran. Special attention is paid to the effect of EPB pressure on the tunnel face displacement. The results of the analysis show that in EPB tunneling, surface settlement and face displacement is related to EPB pressure. Moreover, it is found that tunnel construction sequence is a great effect in face displacement value. For this study, this value in Line 4 where is excavated after line 3, is smaller than that line. In addition, the trend of the displacement curves are changed with the depth for all lines where is located in above and below, close to and above the centerline tunnel face for Line 2, 3 and 4, respectively. It is concluded that: (i) the surface settlement decreases with increasing EPB pressure on the tunnel face; (ii) at a constant EPB pressure, the tunnel face displacement values increase with depth. In addition, this is depended on the tunneling sequence; (iii) the trend of the displacement curves change with the depth.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.500-504
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• 2007

Database are developed to control measured settlement data under construction in Gyungbu High Speed Railway from Daegu to Busan. This means that data having different type at different site could be managed in a unified way. The database includes algorithm to evaluate embankment settlement with settlement data at the surface of embankment and ground settlement data. And also, it has a function to analyse the causes of large settlement over allowable level and high settlement speed based on the log data, embankment specification, physical characteristics of embankment materials.

• Geomechanics and Engineering
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• 제29권3호
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• pp.229-236
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• 2022

In this study, a model experiment and field experiment was conducted to introduce the optimal tensile force when constructing a non-open cut tunnel according to the ground conditions of sandy soil. CMR (Concrete Modular Roof) method is economical because of the high precision and excellent durability, and corrosion resistance, and the inserted parts can be used as the main structure of a tunnel. In addition the CMR method has a stable advantage in interconnection because the concrete beam is press-fitted compared to the NTR (New Tubular Roof) method, and the need for quality control can be minimized. The ground conditions were corrected by adjusting the relative density of sandy soil during the construction of non-open cut tunnels, and after introducing various tensile forces, the surface settlement according to excavation was measured, and the optimal tensile force was derived. As a result of the experiment, the amount of settlement according to the relative density was found to be minor. Furthermore, analysis of each tensile force based on loose ground conditions resulted in an average decrease of approximately 22% in maximum settlement when the force was increased by 0.8 kN per segment. Considering these results, it is indicated that more than 2.0 kN tensile force per segment is recommended for settlement of the upper ground.

• 한국철도학회논문집
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• 제10권5호
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• pp.457-462
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• 2007

콘크리트궤도는 최근 국내에 활발히 적용되고 있다. 콘크리트궤도는 유지보수 비용 저감을 꽤할 수 있다는 장점이 있으나, 콘크리트궤도 구축 후 토공에서 발생할 수 있는 침하를 허용범위 이내로 관리하는 것은 쉽지 않다. 따라서 궤도 공사 이전에 토공 침하를 측정하고 평가하는 것은 매우 중요하다. 원지반과 성토체에서의 침하 거동을 평가하기 위하여 1개의 원지반 침하판, 1개의 하부노반 침하판, 5개의 지표침하핀을 설치하여 성토 완료 후 1년 이상 동안 계측을 수행하였다. 시험개소의 경우 원지반 침하는 시공 중에 완료된 것으로 평가되었다. 그러나 성토체 침하는 성토 완료 후에도 지속적으로 발생하고 있으며, 침하 속도는 점진적으로 감소되는 것을 확인할 수 있었다. 본 논문에서는 침하급증 원인을 분석하여 강우가 침하 급증의 주요원인 중의 하나인 것을 확인하였다.

• 한국터널지하공간학회 논문집
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• 제20권2호
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• pp.433-452
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• 2018

쉴드 TBM 공법은 터널 굴착으로 인한 터널 굴진면과 굴착면의 변형을 억제하여 지반의 변형을 최소화할 수 있는 공법이다. 이를 위해 쉴드 TBM의 운전 조건들을 적절히 제어하는 것은 매우 중요하다. 쉴드 TBM 공법의 여러 가지 운전 조건 중 굴진면압과 뒤채움주입압은 지반에 직접 압력을 가하는 과정으로 굴착에 인한 지반변위의 억제 뿐만 아니라, 지반 내 유효응력 및 간극수압의 변화에 영향을 미치는 요인이다. 굴진면압과 뒤채움압의 작용에 대한 지반의 반응은 지반의 강성 및 투수성에 따라 상이하다. 특히, 포화된 연약 점성토의 경우 굴진면압과 뒤채움압에 의한 지반 내 응력 변화의 영향이 장시간동안 잔류하므로 이에 대한 반응은 투수성이 큰 지반과 구별되는 거동을 보인다. 따라서 본 논문에서는 유한 요소법을 이용한 응력-간극수압 연계 매개변수해석을 통해 포화 점성토 지반에서 쉴드 TBM 운전 조건과 지반의 강성과 투수성이 지표침하에 미치는 영향에 대한 연구를 수행하였다. 연구 결과, 점성토 지반의 지표침하는 즉시침하와 압밀침하로 구분할 수 있었으며, 특히 압밀침하 거동은 지반의 투수성과 강성의 영향을 크게 받는 것으로 나타났다. 또한, 굴진면압과 뒤채움압의 증가가 항상 지표침하 감소로 이어지지는 않고, 임의 크기의 압력(한계 압력) 이상으로 증가된 굴진면압과 뒤채움압은 역으로 지표침하를 증가시키는 요인으로 작용할 수 있음이 확인되었다.

• Geomechanics and Engineering
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• 제22권4호
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• pp.349-359
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• 2020

Quantification of the influence of the fracture of thick magmatic rock (TMR) on the behavior of its overlying strata is a prerequisite to the understanding of the deformation behavior of the earth's surface in deep mining. A three-dimensional numerical model of a special geological mining condition of overlying TMR was developed to investigate the overburden movement and fracture law, and compare the influence of the occurrence horizon of TMR. The research results show that the movement of overlying rock was greatly affected by the TMR. Before the fracture of TMR, the TMR had shielding and controlling effects on the overlying strata, the maximum vertical and horizontal displacement values of overlying strata were 0.68 m and 0.062 m. After the fracture, the vertical and horizontal displacements suddenly increased to 3.06 m and 0.105 m, with an increase of 350% and 69.4%, respectively, and the higher the occurrence of TMR, the smaller the settlement of the overlying strata, but the wider the settlement span, the smaller the corresponding deformation value of the basin edge (the more difficult the surface to crack). These results are of tremendous importance for the control of rock strata and the revealing of surface deformation mechanism under TMR mining conditions in mines.

• Steel and Composite Structures
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• 제52권5호
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• pp.571-581
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• 2024

After a disaster like the catastrophic earthquake, the government have to use rapid assessment of the condition (or damage) of bridges, buildings and other infrastructures is mandatory for rapid feedbacks, rescue and post-event management. This work studies the tracking control problem of a class of strict-feedback nonlinear systems with input saturation nonlinearity. Under the framework of dynamic surface control design, RBF neural networks are introduced to approximate the unknown nonlinear dynamics. In order to address the impact of input saturation nonlinearity in the system, an auxiliary control system is constructed, and by introducing a class of first-order low-pass filters, the problems of large computation and computational explosion caused by repeated differentiation are effectively solved. In response to unknown parameters, corresponding adaptive updating control laws are designed. The goals of this paper are towards access to adequate, safe and affordable housing and basic services, promotion of inclusive and sustainable urbanization and participation, implementation of sustainable and disaster-resilient buildings, sustainable human settlement planning and manage. Simulation results of linear and nonlinear structures show that the proposed method is able to identify structural parameters and their changes due to damage and unknown excitations. Therefore, the goal is believed to achieved in the near future by the ongoing development of AI and control theory.