An Application of Fuzzy Sets to the Blastability Index (BI) Used in Rock Engineering

Rock masses have inherently different resistance to fragmentation by blasting. This property is hereafter referred to as the blastability of a rock mass. Empirical models for the estimation of blastability have been developed. In this study, the Mamdani fuzzy algorithm was used to express the blastability index by fuzzy sets. We use Lilly and Ghose blastability models which are important models of blastability. Parameters of these models were represented by fuzzy sets as the input variables of the fuzzy model. The output of the fuzzy model is a final blastability index rating. Experimental data is obtained from seven mine and one dam sites in Iran. BI values are obtained from both BI fuzzy inference system and conventional BI; Fuzzy sets have more adjustment than conventional model

기계굴착장비의 최적 설계를 위한 픽 커터의 암석 절삭효율 평가

학위논문 (박사)-- 서울대학교 대학원 공과대학 에너지시스템공학부, 2017. 8. 전석원.다양한 암반기계굴착 기법들이 각종 토목․자원 개발 공사에서 적용되어 오고 있고, 발파굴착공법과 비교하여 가지는 안전성, 공사효율, 공사성 등의 장점 때문에 그 적용사례가 점차 증가하고 있는 추세이다. 특히 도심지 터널공사나 해저에서의 파이프/케이블라인 매설에는 기계굴착공법의 적용이 필수적이다. 암반을 굴착하는 기계 장비 중 픽 커터를 굴착도구로 사용하는 TBM, 로드헤더, 트렌쳐, Auger 등은 터널링, 드릴링, 자원개발, 트렌치 공사 등에 광범위하게 활용 될 수 있다. 기계식 굴착장비는 장비의 설계 변경이 매우 어렵기 때문에, 대상 지반의 특성을 고려하여 장비를 설계하고 그 운용조건을 사전에 결정하는 것이 매우 중요하다. 기계굴착장비의 핵심설계변수로는 커터배열, 추력, 토크, 회전속도 등이 있고, 이 설계 변수들은 굴착도구인 픽 커터의 절삭조건 (압입깊이, 커터간격, 절삭각도 등)과 암반의 물성이 절삭력, 절삭효율, 장비의 안정성에 미치는 영향을 종합적으로 고려하여 최적화하여야 한다. 본 연구에서는 픽 커터의 여러 절삭조건들이 절삭성능과 절삭효율에 미치는 영향을 분석하기 위하여 소규모 선형절삭시험 장비를 제작하고 다양한 절삭조건 하에서 선형절삭시험을 수행하였다. 픽 커터의 절삭조건 (압입깊이, 커터간격, Skew angle, Attack angle)과 여러 가지 설계 변수간의 상관관계를 정량적으로 분석하고 절삭효율과 장비의 안정성 측면을 모두 고려하여 최적의 절삭조건을 제안하였다. 또한 암석의 절삭과정에서 발생하는 암편의 크기와 그 분포를 체시험과 이미지 프로세싱 기법을 이용하여 정량적으로 분석하였다. 암편의 크기분포는 굴착효율과 밀접한 상관관계를 보였으며, 암편의 크기가 클수록, 미세분진의 비율이 낮을수록 굴착효율이 높은 절삭조건인 것으로 나타났다. 픽 커터에 의한 암석의 절삭과정을 AUTODYN-3D를 이용하여 수치해석적으로 모사하고, 굴착효율을 평가하였다. 특히 암석절삭해석에서 기존의 그리드기반의 FEM이 가지는 한계점을 극복하기 위하여 SPH기법의 적용성을 평가하고 다수의 커터에 의한 암석의 절삭과정을 모사하는 해석 모델을 제안하였다. SPH기법을 사용한 수치해석모델은 선형절삭시험결과와 비교하여 볼 때 암석의 절삭과정을 현실적으로 모사할 수 있었고, 이를 통해 SPH기법의 적용성을 확인할 수 있었다. 픽 커터를 사용한 트렌칭 커터의 설계과정을 제안하였다. 본 연구에서 얻은 선형절삭 시험결과와 수치해석 결과를 종합하여 트렌칭 커터의 설계를 수행하였고, 트렌칭 커터의 최적운용조건을 제안하였다. 본 연구의 시험결과, 수치해석기법, 설계자료들은 트렌칭 커터의 설계 및 픽 커터를 사용한 다양한 기계굴착장비의 설계에 활용될 수 있을 것으로 기대된다.The application of mechanical excavation method has been used in many civil and mining projects, and its demand has been rapidly increased due to the numerous advantages regarding safety, stability, high advance rate, less environmental impact and construction practice compared with the drill and blasting method. Especially, the mechanical excavation is sometimes essential for the urban, subsea tunneling and subsea trenching. There are many types of mechanical excavators including TBM, roadheader, trencher, and auger, which use pick cutters. Because it is difficult to change the design of the mechanical excavators, it is important to design the machine considering the characteristics of the given geological conditions and to determine the operational conditions in advance. The design parameters of the mechanical excavators are mainly cutter arrangement, thrust, torque, and rotational speed of the cutterhead. These design parameters should be carefully estimated with consideration of the effect of the cutting conditions (i.e., penetration depth, cut spacing, and cutting angle) on the cutting force, cutting efficiency, and mechanical stability of a machine. In this study, a small linear cutting test equipment was manufactured, and a series of tests were performed under various cutting conditions to investigate the effect of various cutting parameters on the cutting performance and the cutting efficiency. This study quantitatively analyzed the relationship between cutting conditions (penetration depth, cut spacing, skew angle and attack angle) and various design parameters of the pick cutter. Then the optimal cutting conditions considering both the cutting efficiency and the stability of the mechanical excavators were suggested. The size and distribution of the rock chip generated during the rock cutting process were quantitatively analyzed using sieve testing and image processing techniques. The size distribution of the rock chips was highly correlated with the rock cutting efficiency. The larger the chip size and the smaller the ratio of rock powder, the higher the cutting efficiency was. The rock cutting process by a pick cutter was numerically simulated using AUTODYN-3D, and the cutting efficiency was evaluated using the developed numerical model. To overcome the limitations of existing grid based FEM in rock cutting simulation, the applicability of SPH (Smooth Particle Hydrodynamics) technique was evaluated, and the numerical model was proposed to simulate the rock cutting process by pick cutters. The SPH method could successfully simulate the rock cutting process that matches with the LCM test result. Therefore, the applicability of the SPH method was validated. The design process of a trenching machine installed with pick cutters was proposed. The operation condition and cutter arrangement were optimally determined based on the results of the linear cutting test and the numerical analysis obtained in this study. As a result of this study, it is expected that the experimental results, numerical model and design process can be used for the design of trenching cutter and the other mechanical excavators using pick cutters1. Introduction 1 1.1 Background 1 1.2 Motivation 10 1.3 Objectives and the structure of the dissertation 12 2. Literature review 14 2.1 Rock cutting mechanism and its parameters 14 2.2 Theoretical studies 21 2.3 Experimental studies 23 2.4 Numerical studies 31 2.5 Chip size distribution 40 3. Methodology 44 3.1 Scaled linear cutting machine system 44 3.2 Experiment design 47 3.3 Experimental set-up 49 3.4 Measurement of chip size distribution 57 4. Results of LCM test 64 4.1 Linyi-sandstone 64 4.2 Concrete 75 4.3 Effect of skew angle 86 4.4 Effect of attack angle 113 4.5 Relieved versus Unrelieved cut 127 5. Chip size analysis 129 5.1 Chip size distribution 129 5.2 Size distribution parameters 133 6. Numerical modelling of rock cutting 152 6.1 Limitation of FEM in rock cutting simulation 152 6.2 Smooth particle hydrodynamics 156 6.3 Numerical Model 163 6.4 Numerical simulation 177 7. Discussion 213 7.1 Analysis of the LCM result 213 7.2 Numerical simulation 222 7.3 Design case of trench cutter 226 8. Conclusions 240Docto

Tunnel boring machine performance prediction in tropically weathered granite through empirical and computational methods

Many works highlight the use of effective parameters in Tunnel Boring Machine (TBM) performance predictive models. However, there is a lack of study considering the effects of tropically weathered rock mass in these models. This research aims to develop several models for predicting Penetration Rate (PR) and Advance Rate (AR) of TBMs in fresh, slightly weathered and moderately weathered zones in granite. To achieve these objectives, an extensive study on 12,649 m of the Pahang- Selangor Raw Water Transfer (PSRWT) tunnel in Malaysia was carried out. The most influential parameters on TBM performance in terms of rock (mass and material) properties and machine specifications were investigated. A database consisting the tunnel length of 5,443 m, 5,530 m and 1,676 m representing fresh, slightly weathered and moderately weathered zones, respectively was analysed. Based on field mapping and laboratory study, a considerable difference of rock mass and material characteristics has been observed. In order to demonstrate the need for developing new models for prediction of TBM performance, two empirical models namely QTBM and Rock Mass Excavatability (RME) were analysed. It was found that empirical models could not predict TBM performance of various weathering zones satisfactorily. Then, multiple regression (i.e. linear and non-linear) analyses were applied to develop new equations for estimating PR and AR. The performance capacity of the multiple regression models could be increased in the mentioned weathering states with overall coefficient of determination (R2) of 0.6. Furthermore, two hybrid intelligent systems (i.e. combination of artificial neural network with particle swarm optimisation and imperialism competitive algorithm) were developed as new techniques in field of TBM performance. By incorporating weathering state as input parameter in hybrid intelligent systems, performance capacity of these models can be significantly improved (R2 = 0.9). With a newly-proposed systems, the results demonstrate superiority of these models in predicting TBM performance in tropically weathered granite compared to other existing and proposed techniques

Marine Power Systems

Marine power systems have been designed to be a safer alternative to stationary plants in order to adhere to the regulations of classification societies. Marine steam boilers recently achieved 10 MPa pressure, in comparison to stationary plants, where a typical boiler pressure of 17 MPa was the standard for years. The latest land-based, ultra-supercritical steam boilers reach 25 MPa pressure and 620 °C temperatures, which increases plant efficiency and reduces fuel consumption. There is little chance that such a plant concept could be applied to ships. The reliability of marine power systems has to be higher due to the lack of available spare parts and services that are available for shore power systems. Some systems are still very expensive and are not able to be widely utilized for commercial merchant fleets such as COGAS, mainly due to the high cost of gas turbines. Submarine vehicles are also part of marine power systems, which have to be reliable and accurate in their operation due to their distant control centers. Materials that are used in marine environments are prone to faster corrosive wear, so special care also should be taken in this regard. The main aim of this Special Issue is to discuss the options and possibilities of utilizing energy in a more economical way, taking into account the reliability of such a system in operation

AI and IoT Meet Mobile Machines: Towards a Smart Working Site

Infrastructure construction is society's cornerstone and economics' catalyst. Therefore, improving mobile machinery's efficiency and reducing their cost of use have enormous economic benefits in the vast and growing construction market. In this thesis, I envision a novel concept smart working site to increase productivity through fleet management from multiple aspects and with Artificial Intelligence (AI) and Internet of Things (IoT)

AI and IoT Meet Mobile Machines

Infrastructure construction is society's cornerstone and economics' catalyst. Therefore, improving mobile machinery's efficiency and reducing their cost of use have enormous economic benefits in the vast and growing construction market. In this thesis, I envision a novel concept smart working site to increase productivity through fleet management from multiple aspects and with Artificial Intelligence (AI) and Internet of Things (IoT)

State of the Art and Future Perspectives in Smart and Sustainable Urban Development

This book contributes to the conceptual and practical knowledge pools in order to improve the research and practice on smart and sustainable urban development by presenting an informed understanding of the subject to scholars, policymakers, and practitioners. This book presents contributions—in the form of research articles, literature reviews, case reports, and short communications—offering insights into the smart and sustainable urban development by conducting in-depth conceptual debates, detailed case study descriptions, thorough empirical investigations, systematic literature reviews, or forecasting analyses. This way, the book forms a repository of relevant information, material, and knowledge to support research, policymaking, practice, and the transferability of experiences to address urbanization and other planetary challenges

The dynamic modelling and development of a controller for a general purpose remotely operated underwater vehicle

A preliminary mathematical model for the UCT SEAHOG Remotely operated underwater vehicle (ROV) is developed, including estimation of the rigid body, hydrodynamic and hydrostatic properties of the robot. A single state thruster model is developed and verified according to real life test data. A closed-loop speed controller is developed for the thruster module using a standard PI scheme and is implemented on an MSP430 microcontroller using software fixed-point algorithms. The complete ROV system is simulated in Simulink® in an open-loop configuration to gain insight into the expected motion from the vehicle. Controllers for depth and heading holding are designed using standard PID linearized control methods with gain scheduling and are then assessed within the complete system in a simulation environment. In addition, upgrades and maintenance are performed on the Power Pod, light and camera modules. Redesign, manufacture and testing of the SEAHOG junction box is performed, including a design solution to connect the tether power and fibre-optic lines at the surface and on the ROV. An extensive overhaul of the SEAHOG GUI is performed, utilising multicore processing architecture in LabVIEW and resulting in a user-orientated interface capable of controlling and monitoring all existing system data from the robot