• Title/Summary/Keyword: Excavation rate

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A Study on the Prediction of Disc Cutter Wear Using TBM Data and Machine Learning Algorithm (TBM 데이터와 머신러닝 기법을 이용한 디스크 커터마모 예측에 관한 연구)

  • Tae-Ho, Kang;Soon-Wook, Choi;Chulho, Lee;Soo-Ho, Chang
    • Tunnel and Underground Space
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    • v.32 no.6
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    • pp.502-517
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    • 2022
  • As the use of TBM increases, research has recently increased to to analyze TBM data with machine learning techniques to predict the exchange cycle of disc cutters, and predict the advance rate of TBM. In this study, a regression prediction of disc cutte wear of slurry shield TBM site was made by combining machine learning based on the machine data and the geotechnical data obtained during the excavation. The data were divided into 7:3 for training and testing the prediction of disc cutter wear, and the hyper-parameters are optimized by cross-validated grid-search over a parameter grid. As a result, gradient boosting based on the ensemble model showed good performance with a determination coefficient of 0.852 and a root-mean-square-error of 3.111 and especially excellent results in fit times along with learning performance. Based on the results, it is judged that the suitability of the prediction model using data including mechanical data and geotechnical information is high. In addition, research is needed to increase the diversity of ground conditions and the amount of disc cutter data.

Investigation of Source Area and Material Characteristics of the Stone Properties from Stone-lined Tombs in Cheongyang Rokpyeong-ri Site, Korea (청양 록평리 유적 석곽묘 석재의 재질특성 및 산지탐색)

  • Il Kyu Choi;Jun Ho Song;Bo Seon Lee;Chan Hee Lee
    • Economic and Environmental Geology
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    • v.56 no.2
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    • pp.201-215
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    • 2023
  • In the stone-lined tombs from Cheongyang Rokpyeong-ri site, several stone-lined tombs corresponding to the Three Kingdoms Period, Unified Silla Period and Goryeo Dynasty were excavated. In this study, the stone properties of petrological, mineralogical and geochemical characteristics from 15 stone-lined tombs were analyzed, the rock species and occupation rate were reviewed, also the provenance area was interpreted. There are five types of rocks used as members of the tombs, including black sandstone, greywacke, slate, conglomerate and gneiss. As a result of magnetic susceptibilities, the rocks of the tombs and presumed provenance are all shown in the same range, and the similarity between the tombs and the source area is high in geochemical behavior characteristics. The stone properties of the tombs are the same as the presumed provenance rocks and is distributed within a 500m around the bedrock of the tombs in the excavation site, so it seems that self-sufficiency was possible on the site without a special procurement system. These stones are interpreted to have been constructed through some trimming without any special technique, but some stone tombs have been confirmed to used homogeneous black sandstone at the bottom of the tombs, so it is believed that there were artificial selection of stones.

A Case Study of Delay Analysis for E.P.B Shield TBM Method in Construction Site (E.P.B(Earth Pressure Balance) Shield TBM 공사의 공기지연 사례연구)

  • Kwak, Jun-Hwan;Park, Hyung-Keun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.6D
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    • pp.737-743
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    • 2009
  • Shield TBM, since it was employed for Suyoungman Bay riverbed tunnel of Busan Subway in 2000,has been increasingly adopted in Korea, and in line with growing popularity, the study on Shield TBM has been expanded. However the studies mostly focus on ground condition in a bid to estimate the advancement rate and develop the model for calculating the excavation efficiency, whereas the efforts to analyze the cause of delay and to develop the improvement measures have been neglected. Thus the studies were mostly intended to analyze the schedule slippage focusing on ground conditions, while the study on schedule behind due to equipment itself and related facilities have yet to be attempted in earnest. This study hence was aimed at evaluating the troubles and schedule slippage caused by mechanical elements such as shield TBM equipment and tools and ground conditions, making use of FMEA approach so as to analyze the risk of schedule delay by such elements, thereby proposing the preventive measures to deal with high-risk factors. So, this study suggest the solution to highly ranked trouble factor for the purpose of enhance the efficiency on Shield TBM.

An Estimation on the Applicability of Hollow FRP Soil Nailing System (중공식 FRP쏘일네일링 시스템의 적용성 평가)

  • Lee, Hyuk-Jin;Koh, Hyung-Seon;Han, Yong-Hee;Kim, Hong-Taek
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.6C
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    • pp.385-393
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    • 2006
  • Soil nailing is a reinforcement method used for stabilizing excavated walls or slopes. Due to its much advantages such as ease of construction and economical efficiency, use of soil nailing is increased. However, the soil nail has much disadvantages for use in urban area. The soil nail needs to be installed inevitably beyond private land boundary, which causes rent for use. For this reason, removable soil nailing system was developed. However, the removal rate of this system is just about 50¢¦70%. To resolve this problem, the Fiber Reinforced Plastic (FRP) soil nailing system which does not need to be removed and allows for the installation beyond private land, is developed. In this paper, through theoretical and experimental studies in laboratory and field such as prototype tests, pullout tests, we evaluate the stability and behavior characteristics of the FRP soil nailing system. And, numerical analyses using FLAC2D were performed with respect to various soil conditions, where prototype test for excavation wall and pullout tests were carried out. As a result of this study, the FRP soil nailing systems show similar behavior characteristics with those of removable soil nailing system. Finally, considering the serviceability and mechanical stability of FRP soil nailing systems, it is enough to be used as a good alternative of general soil nailing system.

Earth Pressure on the Braced Wall in the Composite Ground Depending on the Depth and the Joint Dips of the Base Rocks under the Soil Strata (복합지반 굴착 시 기반암의 깊이와 절리경사에 따라 흙막이벽체에 작용하는 토압)

  • Bae, Sang Su;Lee, Sang Duk
    • Journal of the Korean Geotechnical Society
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    • v.32 no.10
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    • pp.41-53
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    • 2016
  • Stability of the braced earth wall in the composite ground, which is composed of the jointed base rocks and the soil strata depends on the earth pressure acting on it. In most cases, the earth pressure is calculated by the empirical method, in which base rocks are considered as a soil strata with the shear strength parameters of base rocks. In this case the effect of the joint dips of the jointed base rocks is ignored. Therefore, the calculated earth pressure is smaller than the actual earth pressure. In this study, the magnitude and the distribution of the earth pressure acting on the braced wall in the composite ground depending on the joint dips of the base rocks and the ratio of soil strata and base rocks were experimentally studied. Two dimensional large-scale model tests were conducted in a large scale test facility (height 3.0 m, length 3.0 m and width 0.5 m) by installing 10 supports in a scale of 1/14.5. The test ground was presumed with the base rock ratio of the composite ground of 65%:35% and 50%:50% and with the joint dips for each base rock layer, $0^{\circ}$, $30^{\circ}$, $45^{\circ}$ and $60^{\circ}$, respectively. And then finite element analyses were performed in the same condition. As results, the earth pressure on the braced wall increased as the base rock layer's joint dips became larger. And earth pressure at the rock layer increased as the rock rate became larger. The largest earth pressure was measured when the base rock rate was 50% (R50) and the rock layer's joint dips was $60^{\circ}$. Based on these results, a formular for the calculation of the earth pressure in the composite ground could be suggested. Distribution of earth pressure was idealized in a quadrangular form, in which the magnitude and the position of peak earth pressure depended on the rock ratio and the joint dips.

An Analysis of Validity and Satisfaction for Objectives of Small and Medium Business(SMB) Administration Subsidy the Human Resource Development Program(HRDP) and the Customized Employment Program(CEP) in Specialized High Schools (중소기업 특성화고 인력양성사업과 취업맞춤반의 성과 목표에 대한 타당도 및 만족도 분석 연구)

  • Lee, Byung Wook;Ahn, Jae Yeong;Kang, Chol Min
    • 대한공업교육학회지
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    • v.41 no.1
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    • pp.68-87
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    • 2016
  • This research conducted a survey for total 166 teachers of schools so as to analyze validity and satisfaction for performance objectives of SMB administration subsidy the HRDP and the CEP in Specialized High School. The results of research are as follows. First, teachers recognize that purpose of HRDP is to expand employment of specialized high school and provide human resource of SMB. And, they recognize that HRDP is important to improve school outcomes and makes a positive effect on the improvement of school outcomes. Second, teachers recognize that objectives of HRDP are improvement of student's understanding for SMB, improvement of teacher's understanding for SMB, improvement of SMB's understanding of school, cultivation of student's occupational view, systematization of career guiding program based on employment process, strengthening of industry-academia cooperation education, improvement of the level of student's skill, fulfillment of workplace experience and practice focusing workplace learning, training of customized human resource for SMB, improvement of student's adaptation to the workplace, improvement of employment rate for SMB, expansion of job opportunities for students with SMB, preparation of the base of connection between school and SMB, publicity of school, expansion of opportunities to cooperate between SMB and school, establishment of cooperative system among industrial association and school, introduction and operation of the employment connective model for joint education and employment, strengthening of field professionalism of teachers. However, satisfaction for the achievement of objectives of HRDP except for strengthening of industry-academia cooperation education and improvement of employment rate for SMB is relatively lower than the validity. Third, teachers in charge of human resource training business of middle and small sized company's specialized high school recognize that objectives of CEP are expansion of job opportunities for students with SMB, excavation of good-quality SMB, expansion of opportunities to cooperate between SMB and school, fulfillment of workplace learning, improvement of student's major foundation and in-depth skill, improvement of literacy, math, teamwork and communication abilities for students' job performance, improvement of student's working attitude and student's proper career exploration decision. However, satisfaction for achievement of objectives of CEP is relatively lower than the validity.

Setup of Infiltration Galleries and Preliminary Test for Estimating Its Effectiveness in Sangdae-ri Water Curtain Cultivation Area of Cheongju, Korea (청주 상대리 수막재배지의 지중 침투형 갤러리 설치와 예비 주입시험)

  • Moon, Sang-Ho;Kim, Yongcheol;Kim, Sung-Yun;Ki, Min-Gyu
    • Economic and Environmental Geology
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    • v.49 no.6
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    • pp.445-458
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    • 2016
  • Most of water curtain cultivation (WCC) area in Korea has been inveterately suffering from the gradual draw-down of groundwater level and related shortage of water resources at the late stage of WCC peak time. To solve this problem, artificial recharge techniques has been recently applied to some WCC area. This study introduces infiltration gallery, which is one of the artificial recharge methods, and tentatively examined the effectiveness of three galleries installed at Sangdae-ri WCC area of Cheongju City. Seven galleries are set up at each empty space between eight vinyl houses in this area and its dimension is designed as 50 cm in each width and height and 300 cm in each length. Installation process was including bed excavation, backfill with gravels and silica sands, and completion of gallery by equipment of piezometer and covering with non-woven cloth. For each B, C, D gallery, 3 types of test including preliminary, four step and one long-term injection were performed. The first preliminary test showed the rough relations between injection rates and water level rise as follows; 20 cm and 30 cm level rise for $33.29{\sim}33.84m^3/d$ and $45.60{\sim}46.99m^3/d$ in B gallery; 0 cm, 16 cm and 33 cm level rise for $21.1m^3/d$, $33.98m^3/d$ and $41.69m^3/d$ in C gallery; 29 cm and 42 cm level rise for $48.10m^3/d$ and $52.23m^3/d$ in D gallery. Afterwards, more quantitative results estimating effectiveness of artificial recharge were reasoned out through stepped and long-term injection tests, which is expected to be employed for estimating water quantity re-injected into the aquifer through these galleries by natural injection over the period of WCC peak time.

Mineralogical Composition and Physical Variation of Reproduced Potteries based on Chemical Composition and Firing Temperature (화학조성과 소성온도에 따른 재현 토기의 광물조성과 물성변화)

  • Kim, Su-Kyoung;Han, Min-Su;Moon, Eun-Jung;Kim, Young-Hee;Hwang, Jin-Ju;Lee, Han-Hyoung
    • Journal of Conservation Science
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    • v.26 no.3
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    • pp.311-324
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    • 2010
  • The purpose of this study aims to reveal characteristics of reproduced potteries which made with clays of various chemical compositions in different firing temperatures and thereafter to provide comparative samples for identifying the manufacturing techniques of earthenwares from archaeological excavation by reproducing and characterizing sample under controlled conditions. For this study, various samples of earthenware are reproduced using different types of raw clays at several different firing temperature, followed by physical and structural characterization. Chemical specification were varied from different types of clay, which were calculated by Seger formula, and four different types of clay were selected based on different mole ratio of acidic oxide. The temperatures of firing of 7 samples were varied between $600^{\circ}C$ to $1200^{\circ}C$ at the interval of $100^{\circ}C$ for each sample. The result of analysis revealed that each reproduced earthenware has different chemical compositions divided into two groups: 1. Sample Y(6.10) and Sample G(5.85) clay; 2. Sample H(3.41) and Sample S(2.85) clay. The former which has higher mole ratio of acidic oxide than the latter, shows higher level of rockwell hardness at the same firing temperature. In addition, all four samples presented that as the firing temperature was increased, absorption rates of Y and G were abruptly dropped at $1200^{\circ}C$. Furthermore the more mole ratio of acidic oxide increase, the more microtexture of samples were vitrificated. Such result reveals that mole ratio of acidic oxide influence physical and microtextural characteristics of earthenwares, and it can be used as the comparison data in the understanding of manufacture techniques for the earthenwares of similar chemical composition.

Evaluation of mechanical characteristics of marine clay by thawing after artificial ground freezing method (인공동결공법 적용 후 융해에 따른 해성 점토지반의 역학적 특성 평가)

  • Choi, Hyun-Jun;Lee, Dongseop;Lee, Hyobum;Son, Young-Jin;Choi, Hangseok
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.1
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    • pp.31-48
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    • 2019
  • The artificial ground freezing (AGF) method is a groundwater cutoff and/or ground reinforcement method suitable for constructing underground structures in soft ground and urban areas. The AGF method conducts a freezing process by employing a refrigerant circulating through a set of embedded freezing pipes to form frozen walls serving as excavation supports and/or cutoff walls. However, thermal expansion of the pore water during freezing may cause excessive deformation of the ground. On the other hand, as the frozen soil is thawed after completion of the construction, mechanical characteristics of the thawed soil are changed due to the plastic deformation of the ground and the rearrangement of soil fabric. This paper performed a field experiment to evaluate the freezing rate of marine clay in the application of the AGF method. The field experiment was carried out by circulating liquid nitrogen, which is a cryogenic refrigerant, through one freezing pipe installed at a depth of 3.2 m in the ground. Also, a piezo-cone penetration test (CPTu) and a lateral load test (LLT) were performed on the marine clay before and after application of the AGF method to evaluate a change in strength and stiffness of it, which was induced by freezing-thawing. The experimental results indicate that about 11.9 tons of liquid nitrogen were consumed for 3.5 days to form a cylindrical frozen body with a volume of about $2.12m^3$. In addition, the strength and stiffness of the ground were reduced by 48.5% and 22.7%, respectively, after a freezing-thawing cycle.

한강하류지형면의 분류와 지형발달에 대한 연구 (양수리에서 능곡까지)

  • Park, No-Sik
    • Journal of the Speleological Society of Korea
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    • no.68
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    • pp.23-73
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    • 2005
  • Purpose of study; The purpose of this study is specifically classified as two parts. The one is to attempt the chronological annals of Quaternary topographic surface through the study over the formation process of alluvial surfaces in our country, setting forth the alluvial surfaces lower-parts of Han River area, as the basic deposit, and comparing it to the marginal landform surfaces. The other is to attempt the classification of micro morphology based on the and condition premising the land use as a link for the regional development in the lower-parts of Han river area. Reasons why selected the Lower-parts of Han river area as study objects: 1. The change of river course in this area is very serve both in vertical and horizontal sides. With a situation it is very easy to know about the old geography related to the formation process of topography. 2. The component materials of gravel, sand, silt and clay are deposited in this area. Making it the available data, it is possible to consider about not oかy the formation process of topography but alsoon the development history to some extent. 3. The earthen vessel, a fossil shell fish, bone, cnarcoal and sea-weed are included in the alluvial deposition in this area. These can be also valuable data related to the chronological annals. 4. The bottom set conglometate beds is also included in the alluvial deposits. This can be also valuable data related to the research of geomorphological development. 5. Around of this area the medium landform surface, lower landform surface, pediment and basin, are existed, and these enable the comparison between the erosion surfaces and the alluvial surfaces. Approach : 1. Referring to the change of river beds, I have calculated the vertical and horizontal differences comparing the topographic map published in 1916 with that published in 1966 and through the field work 2. In classifying the landform, I have applied the method of micro morphological classification in accordance with the synthetic index based upon the land conditions, and furthermore used the classification method comparing the topographic map published in 1916 and in that of 1966. 3. I have accorded this classification with the classification by mapping through appliying the method of classification in the development history for the field work making the component materials as the available data. 4. I have used the component materials, which were picked up form the outcrop of 10 places and bored at 5 places, as the available data. 5. I have referred to Hydrological survey data of the ministry of Construction (since 1916) on the overflow of Han-river, and used geologic map of Seoul metropolitan area. Survey Data, and general map published in 1916 by the Japanese Army Survbey Dept., and map published in 1966 by the Construction Research Laboratory and ROK Army Survey Dept., respectively. Conclusion: 1. Classification of Morphology: I have added the historical consideration for development, making the component materials and fossil as the data, to the typical consideration in accordance with the map of summit level, reliefe and slope distribution. In connection with the erosion surface, I have divided into three classification such as high, medium and low-,level landform surfaces which were classified as high and low level landform surfaces in past. furthermore I have divided the low level landform surface two parts, namely upper-parts(200-300m) and bellow-parts(${\pm}100m$). Accordingly, we can recognize the three-parts of erosion surface including the medium level landform surface (500-600m) in this area. (see table 22). In condition with the alluvial surfaces I have classified as two landform surfaces (old and new) which was regarded as one face in past. Meamwhile, under the premise of land use, the synthetic, micro morphological classification based upon the land condition is as per the draw No. 19-1. This is the quite new method of classification which was at first attempted in this country. 2. I have learned that the change of river was most severe at seeing the river meandering rate from Dangjung-ni to Nanjido. As you seee the table and the vertical and horizontal change of river beds is justly proportionable to the river meandering rate. 3. It can be learned at seeing the analysis of component materials of alluvial deposits that the component from each other by areas, however, in the deposits relationship upper stream, and between upper parts and below parts I couldn't always find out the regular ones. 4. Having earthern vessel, shell bone, fossil charcoal and and seaweeds includen in the component materials such as gravel, clay, sand and silt in Dukso and Songpa deposits area. I have become to attempt the compilation of chronicle as yon see in the table 22. 5. In according to hearing of basemen excavation, the bottom set conglomerate beds of Dukso beds of Dukso-beds is 7m and Songpa-beds is 10m. In according to information of dredger it is approx. 20m in the down stream. 6. Making these two beds as the standard beds, I have compared it to other beds. 7 The coarse sand beds which is covering the clay-beds of Dukso-beds and Nanjidobeds is shown the existence of so-called erosion period which formed the gap among the alluvial deposits of stratum. The former has been proved by the sorting, bedding and roundness which was supplied by the main stream and later by the branch stream, respectively. 8. If the clay-beds of Dukeo-bed and Songpa-bed is called as being transgressive overlap, by the Eustatic movement after glacial age, the bottom set conglomerate beds shall be called as being regressive overlap at the holocene. This has the closest relationship with the basin formation movement of Seoul besides the Eustatic movement. 9. The silt-beds which is the main component of deposits of flood plain, is regarded as being deposited at the Holocene in the comb ceramic and plain pottery ages. This has the closest relationship with the change of river course and river beds.