• Title/Summary/Keyword: Up and Down method

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A Study on Crack Reduction Method in open Section of Down-Up Underground Construction Method Affected by Earth Pressure (토압 영향을 받는 Down-Up 지하공사 공법의 오픈 구간 균열 저감 방안 연구)

  • Shim, Hak-Bo;Jeon, Hyun-Soo;Seok, Won-Kyun
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2021.11a
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    • pp.196-197
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    • 2021
  • The underground method can be divided into Top-Down, Semi-Top-Down, Up-Up and Down-Up methods according to the construction order of the upper and lower structures. Among them, the Down-Up method proceeds with the construction of the first floor and its lower floors, and when the foundation is completed, the vertical members of the basement are sequentially completed from the foundation and the above-ground floor is constructed. In this paper, the crack reduction method around the open section of the Down-Up method affected by earth pressure was analyzed and divided into design and construction parts.

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Numerical Approach to Evaluate the Behavior of Concrete Panel Considering Construction Method (수치해석을 이용한 시공방법에 따른 판넬식 옹벽의 거동 분석에 관한 연구)

  • Junhee, Kang;Hoki, Ban
    • Journal of the Korean GEO-environmental Society
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    • v.23 no.12
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    • pp.17-23
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    • 2022
  • This paper analyze the precast panel retaining wall's safety factor changes based on the numerical analysis using PLAXIS 2D software. Numerical analysis conditions include construction method, nail and panel fixing method, backfill material compaction conditions, rainfall conditions. The classification according to the construction method of the precast panel retaining wall includes the top-down and bottom-up methods. The difference between the top-down and bottom-up methods is the presence or absence backfill material and the ground excavation method. The top-down method involves vertically excavating the ground and attaching the panel using mortar, but in the bottom-up method, the ground is vertically excavated and harden the backfill material. As a result of numerical analysis, the top-down method secured a higher safety factor in all cases except the rainfall conditions.

A Study on the Sub-elements of the Top-down Construction Method Selection Model using Weighting Factor in Downtown Area (가중치 분석을 통한 도심지 Top-Down 공사에서의 공법요소 선정 모델 개발에 관한 연구)

  • Park, Chang-Wook;Moon, Seung-Yun;Yun, Seok-Heon
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.4
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    • pp.61-69
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    • 2008
  • The size of the construction projects become huge and complex, and the depth of excavation for the underground structures become deeper. Also the working area is not enough for loading materials and temporary facilities. This is the most case of recent construction projects in downtown area. Top-down is the most useful method for this kind of construction projects. Top-down construction method consists of supporting method, retaining wall type, foundation type and construction direction such as up-down or up-up. construction managers have to select sub-elements for top-down construction method in planning phase. This study is to suggest the sub-elements selection model for the top-down construction method, and the case study is conducted for evaluating this model.

A Study on the New Learning Method to Improve Noise Tolerance in Fuzzy ART (퍼지 ART에서 잡음 여유도를 개선하기 위한 새로운 학습방법의 연구)

  • 이창주;이상윤;이충웅
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.32B no.10
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    • pp.1358-1363
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    • 1995
  • This paper presents a new learning method for a noise tolerant Fuzzy ART. In the conventional Fuzzy ART, the top-down and bottom-up weight vectors have the same value. They are updated by a fuzzy AND operation between the input vector and the current value of the top-down or bottom- up weight vectors. However, it can not prevent the abrupt change of the weight vector and can not achieve good performance for a noisy input vector. To solve the problems, we updated using the weighted sum of the input vector and the current value of the top-down vector. To achieve stability, the bottom-up weight vector is updated using the fuzzy AND operation between the newly learned top-down vector and the current value of the bottom-up vector. Computer simulations show that the proposed method prominently resolves the category proliferation problem without increasing the training epoch for stabilization in noisy environments.

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Analysis of Cases Using Top-Down Construction Method Under Various Site Condition (현장 조건에 따른 Top-Down 공법 사례분석에 관한 연구)

  • Shin, Hyun-Jung;Shin, Kyoo-Chul
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2011.05a
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    • pp.197-199
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    • 2011
  • To utilize the Top-Down construction method, it is required to analyse building area, floors, and soil conditions to choose the three basic elements of retaining wall, base column, and floor structure. The purpose of this research is to compare the methods of Top-Down with other construction methods. The research method is to analyse the project conditions of Top-Down project cases. The aim is to develop a method of selecting alternatives, considering construction characteristics, work schedule, supporting methods, foundation types.

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The Algorithm of Simulation and Justification of the Use of Conditional Likclihood in Up-and-Down Method

  • Hyonggi Jung
    • Communications for Statistical Applications and Methods
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    • v.4 no.1
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    • pp.271-280
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    • 1997
  • It should be noted that the number of observation in the up-and-down procedure is a random variable. Therefore, We need to justify the employment of the conditional likelihood even in the above situation and show the algorithm of simulation. Also, the strategy of halving or widening the level space in modified up-and-down method is suggested.

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Study on the Application of Semi-open cut Top-Down Construction for Framework (세미 오픈컷 역타공법의 현장적용에 관한 연구)

  • Sho, Kwang-Ho
    • Journal of Korean Association for Spatial Structures
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    • v.11 no.2
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    • pp.129-138
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    • 2011
  • Construction methods for underground structure are classified as bottom-up, up-up, and top-down methods depending on the procedure of construction related to a superstructure. In top-down construction methods, building's main structure is built from the ground level downwards by sequentially alternating ground excavation and structure construction. In the mean time, the main structure is also used as supporting structure for earth-retaining wall, which results in the increased stability of the earth-retaining wall due to the minimized deformation in adjacent structures and surrounding grounds. In addition, the method makes it easy to secure a field for construction work in the downtown area by using each floor slabs as working spaces. However top-down construction method is often avoided since an excavation under the slab has low efficiency and difficult environment for work, and high cost compared with earth anchor method. This paper proposes a combined construction method where semi-open cut is selected as excavation work, slurry as earth -retaining wall and CWS as top-down construction method. In the case study targeted for an actual construction project, the proposed method is compared with existing top-down construction method in terms of economic feasibility, construction period and work efficiency. The proposed construction method results in increased work efficiency in the transportation of earth and sand, and steel frame erection, better quality management in PHD construction, and reduced construction period.

A Study on the Grouting Characteristics of Top-down Multi-step Pressure Grouting Method (하향식 다단 압력 그라우팅 방법의 주입특성에 대한 연구)

  • Lee, Hongsung;Lee, Seungho
    • The Journal of Engineering Geology
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    • v.29 no.3
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    • pp.201-209
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    • 2019
  • Bottom-up multi-stage pressure grouting is widely applied to domestic slopes and tunnels. It involves injecting earth from the ground to the surface after drilling. Various reports of construction performance have demonstrated its wide applicability. However, little research has studied top-down multi-step pressure grouting in Korea, which involves injection from the surface. This paper compares the grouting effect of both the established bottom-up method and the top-down method in soil box and field tests. The soil box test showed that the bulb volume of the top-down method is ~24% less than that of the bottom-up method. The field test confirmed that the top-down method has a wider grouting range and a higher injection density per area than the bottom-up method.

Experimental verification of shear and frictional characteristics in end milling (엔드밀링시 전단 및 마찰 특성의 실험적 검증)

  • Lee, Y. M.;S. H. Yang;M. Chen;S. I. Jang
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1789-1794
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    • 2003
  • As a new approach to analyze shear behaviors in the shear plane and chip-tool friction behaviors in the chip-tool contact region during an end milling process, this paper introduces a method to transform an end milling process to an equivalent oblique cutting process. In this approach, varying undeformed chip thicknesses and cutting forces in the up-and down-end milling process are replaced with the equivalent ones of oblique cutting. Accordingly, in the current paper, the shear and friction characteristics of end milling operations, up- and down-end milling, have been analyzed based on the equivalent oblique cutting models. Two series of cutting tests, up- and down-end milling tests and the equivalent oblique cutting tests to that, have been carried out to verify the validity of the analyses. And using the results of cutting tests the cutting characteristics of the up- and down-end milling processes have been thoroughly investigated.

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Study on the Prestressing Effect of 3 Span Continuous Preflex Composite Beam of Bridges by Re-Up Down of Supports (지점 재 상승·하강에 의한 3경간 연속 프리플렉스 합성형의 프리스트레싱 효과에 관한 연구)

  • Koo, Min Se;Park, Young Je;Kim, Phil Sik
    • Journal of Korean Society of Steel Construction
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    • v.13 no.4
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    • pp.433-441
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    • 2001
  • Thus study presents the basic concepts of 3 span continuous preflex composite beam of bridges by re-up down of supports and analysis relationship of between variables and stress of critical section. Also, it shows the pre-compression effects of re-up down of supports method by presenting the difference of between old section and new section got from new method. This study's new method makes more economic sections to be possible and when the sections designed with the existing method are used in the new method. efficient stress state is accomplished.

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