Characteristics of boulders formed in tropical weathered granite: a review

Boulder is well known as one of the obstruction material and problematic to the underground excavations and constructions. Although the presence of boulder in weathered rock mass was revealed and reported by many researchers, but the occurrence and physical characteristics of boulders in weathering profile are still not clearly understood. This paper attempts to revise the issues and characteristics of boulder formed in weathered granite which include the formation, distribution, properties and location of boulders found in tropical weathering profile. As a weathering product, boulder is dominantly found in moderately to completely weathered zone of rock mass (Grade III to V). Boulder consists of corestone Grade I or II and surrounded by some concentric sheet of weathered rock Grade III to V or rindlets which formed due the reaction of spheroidal weathering. The rindlets with thickness ranges 0.2 mm to 2.0 m is the zone of decomposition and dissolution of biotite and feldspar that gradually transforming to saprolite. This information is useful to geotechnical engineers and researchers for engineering purposes and weathering zone classification especially in underground excavation and structure design

Classification of filled joint based on the characteristics of its constitutive components

Filled joints in rock mass pose a number of constructional problems. When filled joints are reckoned to be critical to an engineering structure, their behaviours are often studied using expensive in-situ testing and complex full-scale physical modelling. This is because sampling of an undisturbed filled joint is almost impossible to undertake. As such, a means of anticipating the behaviour and characteristics of this critical geological discontinuity is important. One method to predict the behaviour of filled joint is through systematic classification based on its essential components, particularly those features that control the behaviour of the joint under shear and compressive load. Exposed filled joints in granite rock in Lahat, Perak, have been selected for the field study. The field assessments indicate there are several components of filled joint that exhibit certain geological and mechanical characteristics which can be identified and assessed in the field and laboratory. For the infilling material, the essential features include thickness, weathering grade and texture. For the host joint blocks, the features include texture and roughness of the joint surface and weathering degree of the blocks. The weathering grade of the infill and joint blocks are geological characteristics that can be graded according to the standard classification system. The samples of infilling were further evaluated in the laboratory using index and characterisation tests like sieving, compression and shear tests. This study has shown that there are several essential components of filled joint that can be used to predict its behaviour. These components can be easily characterised and evaluated in the field and laboratory. The characteristics of the infilling material and roughness of joint surface are among the features that control the behaviour of filled joint, and subsequently can be used as classification index for predicting the joint behaviour

Intelligence prediction of some selected environmental issues of blasting: A review

Background: Blasting is commonly used for loosening hard rock during excavation for generating the desired rock fragmentation required for optimizing the productivity of downstream operations. The environmental impacts resulting from such blasting operations include the generation of flyrock, ground vibrations, air over pressure (AOp) and rock fragmentation. Objective: The purpose of this research is to evaluate the suitability of different computational techniques for the prediction of these environmental effects and to determine the key factors which contribute to each of these effects. This paper also identifies future research needs for the prediction of the environmental effects of blasting operations in hard rock. Methods: The various computational techniques utilized by the researchers in predicting blasting environmental issues such as artificial neural network (ANN), fuzzy interface system (FIS), imperialist competitive algorithm (ICA), and particle swarm optimization (PSO), were reviewed. Results: The results indicated that ANN, FIS and ANN-ICA were the best models for prediction of flyrock distance. FIS model was the best technique for the prediction of AOp and ground vibration. On the other hand, ANN was found to be the best for the assessment of fragmentation. Conclusion and Recommendation: It can be concluded that FIS, ANN-PSO, ANN-ICA models perform better than ANN models for the prediction of environmental issues of blasting using the same database. This paper further discusses how some of these techniques can be implemented by mining engineers and blasting team members at operating mines for predicting blast performance

A Novel Approach for Blast-Induced Flyrock Prediction Based on Imperialist Competitive Algorithm and Artificial Neural Network

Flyrock is one of the major disturbances induced by blasting which may cause severe damage to nearby structures. This phenomenon has to be precisely predicted and subsequently controlled through the changing in the blast design to minimize potential risk of blasting. The scope of this study is to predict flyrock induced by blasting through a novel approach based on the combination of imperialist competitive algorithm (ICA) and artificial neural network (ANN). For this purpose, the parameters of 113 blasting operations were accurately recorded and flyrock distances were measured for each operation. By applying the sensitivity analysis, maximum charge per delay and powder factor were determined as the most influential parameters on flyrock. In the light of this analysis, two new empirical predictors were developed to predict flyrock distance. For a comparison purpose, a predeveloped backpropagation (BP) ANN was developed and the results were compared with those of the proposed ICA-ANN model and empirical predictors. The results clearly showed the superiority of the proposed ICA-ANN model in comparison with the proposed BP-ANN model and empirical approaches

Numerical Modelling for Geoengineering in Tropical Region

‘Tropics’ include all areas on the earth where the Sun contacts a point directly overhead at least once during the solar year, and located surrounding the Equator. The tropics comprise 40% of the earth’s surface area and contain 36% of earth’s landmass. Tropical is sometimes used in a general sense for a tropical climate which means warm to hot and moist year-round. Tropical areas tend to experience more rapid weathering because large amounts of consistent rainfall and constantly warm temperatures that influence the rate of weathering. Tropical areas usually experience both, dry and wet season. The wet /rainy /green season is the time of year, ranging from one or more months, when most of the average annual rainfall in a region falls. This rapid change of hot and cold weather more or less influenced the geology characteristics of the area such as the weathering rate, the soil formation. The uniqueness of geological characteristics in tropical regions has intrigued researchers to explore in details as to how this climate condition influenced the in situ geotechnical process and geological characteristics in order to identify the issues and challenges faced by geotechnical engineers when doing construction in the region. In an ever more globalized world, we are compelled to embrace the technological advancement in order to stay competitive. Hence, by using numerical methods to solve geotechnical problems and analysis are seen to be one of the initiatives to excel in this field especially in tropical geoengineering.Numerical analysis using finite element and finite difference methods has become a mainstream design tool within geotechnical engineering in the last decades. Numerical modelling is a mature yet vibrant research area in geotechnical engineering. Its advancement has been accelerated in recent years by many emerging computational techniques as well as the increasing availability of computational power. A wide spectrum of approaches, on the basis of continuously advancing understanding of soil behaviour, has been developed and applied to solve various problems in geotechnical engineering. The aim of this edited book is to present original research output by fellows and members of Centre of Tropical Geoengineering (GEOTROPIK) that applied numerical modelling in their analysis of geoengineering in tropical regions. The study area are mostly located in Asian region such as Malaysia, Thailand and Sri Lanka. This book is themed around numerical modeling application in rock mechanics and geology engineering, geotechnical engineering, and geoinformation to measure, manage and analyze the geospatial data relating the earth and its application in tropical regions. This theme is in line with the function of GEOTROPIK as research centre and provider of consultancy services. I thankfully acknowledge the authors for their valuable contribution in this book. Last but not least I feel indebted to reviewers, fellow editors and all those who helped directly or indirectly to make this book a successful and notable remembrance

Effect of geological structure and blasting practice in fly rock accident at Johor, Malaysia

Blasting operation is common method in hard rock excavation at civil engineering and mining sites. Rock blasting results in the fragmentation along with environmental hazards such as fly rock, ground vibration, air-blast, dust and fumes. Most of the common accidents associated with blasting are due to fly rock. A fly rock accident had occurred on 15 July 2015 at a construction site at Johor, Malaysia. Due to this accident, nearby factory worker was killed while two other workers were seriously injured after being hit by rock debris from an explosion at construction site, 200 m away from the factory. The main purpose of this study is to investigate the causes of fly rock accident based on geological structures and blasting practice such as blast design, pre inspection on geological structures, identifying danger zone due to blasting and communication and evacuation of personnel before blast. It can be concluded that fly rock could have been controlled in three stages; initial drilling of holes based on blast design, ensure limiting charge for holes having less burden or having geological discontinuity, and selecting proper sequence of initiation of holes

Excavation assessment in wet tropically sedimentary rock

The selection of suitable methods to be employed for surface excavation works is particularly important in geotechnical engineering projects. Factors such as environmental constrains, rock properties and size of site may affect the selection of machine required for surface excavation. Wrong selection of equipment and technique can result in unrecoverable expenses and thus, should be avoided. Great challenges in excavation works are expected in sedimentary rock where the occurrence of discontinuity such as bedding thickness, foliation and the inhomogeneity of rock as well as effect of moisture can greatly affect its excavatability. This paper aims to identify and highlight the factors affecting the excavation works in wet tropically weathered sedimentary area as what have been experienced in Malaysia. Some of these factors, however, are not specified in the existing general excavatability assessments. Assessment by practical excavation was carried out at three sedimentary rock sites in Nusajaya, Malaysia, taking into account the related parameters. Statistical analysis by using SPSS was then being conducted in order to determine the correlation of each parameter with productivity of excavation and their significance in affecting the excavatability.Based on the results obtained, it was found that the parameters such as Is50, R, UCS, density, ITS, Js, JL, Jd, IP and moisture content play significant roles in affecting the excavatability of sedimentary rocks. Meanwhile, the existence of bedding, Id2 and Jn are deemed to be neglected. It is believed that this study can help to enhance the knowledge on factors that complicate the excavation works in sedimentary area

Estimating uniaxial compressive strength of tropically weathered sedimentary rock using indirect tests

Uniaxial compressive strength (UCS) of intact rock is particularly important in rock mechanic studies, especially for those involving civil and mining projects. However, the determination of UCS using direct test is generally expensive, time consuming and almost impossible in preparation of samples for highly weathered sedimentary rocks. In view of this, indirect tests are comparatively cheap, simpler, faster and more convenient to perform either in laboratory or at site. This paper aims to develop an estimation procedure in determining the UCS values of such weak weathered rocks. Among the indirect tests present herein are point load index, Schmidt Rebound hammer, Brazilian tensile test and slake durability test. Unfortunately, it was found that the accuracy of each single test varies with weathering states. Hence, a recommended procedure using combined indirect tests in determining UCS of weak sedimentary rocks is presented herei

Effectual excavation of weathered rocks using geological features

In the tropical region where the occurrence of a thick profile of weathered zone is common, ripping is always accepted as the limit of mechanical breaking before blasting works is opted. However, the nature of rock and its weathering profile play a very significant role in evaluating the excavation assessment. Many issues have emerged in ripping work for sedimentary area where the occurrence of bedding, foliation and the inhomogeniety of rock can greatly influence the excavatability of the weathered rocks. This chapter aims to highlight some of the problems that arise in weathered sedimentary areas and as what have been experienced during the implementation of surface excavation works

Applications of two neuro-based metaheuristic techniques in evaluating ground vibration resulting from tunnel blasting

Peak particle velocity (PPV) caused by blasting is an unfavorable environmental issue that can damage neighboring structures or equipment. Hence, a reliable prediction and minimization of PPV are essential for a blasting site. To estimate PPV caused by tunnel blasting, this paper proposes two neuro-based metaheuristic models: neuro-imperialism and neuro-swarm. The prediction was made based on extensive observation and data collecting from a tunnelling project that was concerned about the presence of a temple near the blasting operations and tunnel site. A detailed modeling procedure was conducted to estimate PPV values using both empirical methods and intelligence techniques. As a fair comparison, a base model considered a benchmark in intelligent modeling, artificial neural network (ANN), was also built to predict the same output. The developed models were evaluated using several calculated statistical indices, such as variance account for (VAF) and a-20 index. The empirical equation findings revealed that there is still room for improvement by implementing other techniques. This paper demonstrated this improvement by proposing the neuro-swarm, neuro-imperialism, and ANN models. The neuro-swarm model outperforms the others in terms of accuracy. VAF values of 90.318% and 90.606% and a-20 index values of 0.374 and 0.355 for training and testing sets, respectively, were obtained for the neuro-swarm model to predict PPV induced by blasting. The proposed neuro-based metaheuristic models in this investigation can be utilized to predict PPV values with an acceptable level of accuracy within the site conditions and input ranges used in this study