A geological approach toward developing a mudrock-durability classification system

1994 ◽  
Vol 31 (1) ◽  
pp. 17-27 ◽  
Author(s):  
Jeffrey C. Dick ◽  
Abdul Shakoor ◽  
Neil Wells
Keyword(s):  
North America ◽  
Key Words ◽  
Classification System ◽  
Void Ratio ◽  
Clay Content ◽  
Dry Density ◽  
Slake Durability Index ◽  
Durability Index ◽  
Degree Of Consolidation ◽  
Clay Mineral Composition

Relationships between durability and lithologic characteristics of 61 mudrock samples from North America were investigated with the objective of developing a mudrock-durability classification based on lithologic characteristics. Second-cycle slake-durability index (Id2) was used as a measure of durability, whereas clay content, clay-mineral composition, texture, microfracture frequency, absorption, adsorption, dry density, void ratio, and Atterberg limits were used to characterize mudrock lithology. Based upon the amount of clay-size material, the presence or absence of laminations, and the degree of induration, the mudrocks were subdivided into claystones, mudstones, siltstones, shales, and argillites. The relationships between durability and lithologic characteristics were investigated separately for each class of mudrocks. The results show that different lithologic characteristics best correlate with the durability of each class of mudrocks. The durability of claystones correlates best with the amount of expandable clay minerals and that of mudstones with the frequency of microfractures. The degree of consolidation, as expressed by absorption, influences the durability of both siltstones and shales. The durability of argillites is related to their crystalline texture. Lithologic characteristics can be quantitatively related to a durability classification proposed herein that recognizes three classes of durability: low (Id2 < 50%), medium (Id2 = 50%–85%), and high (Id2 > 85%). Key words : mudrock, durability, lithologic characteristics, classification.

scholarly journals Geological and Engineering Classification Systems of Mudrocks

2000 ◽  
Vol 5 ◽  
pp. 137 ◽  
Author(s):  
Amer Al-Rawas ◽  
Tariq Cheema ◽  
Mohammed Al-Aghbari
Keyword(s):  
Grain Size ◽  
Clay Content ◽  
Classification Systems ◽  
Research Attention ◽  
Slake Durability Index ◽  
Fine Grained ◽  
Durability Index ◽  
Different Types ◽  
Engineering Projects

Mudrocks are a diverse group of very fine-grained argillaceous sedimentary rocks that are frequently encountered in most types of engineering projects. Upon excavation, the release of overburden stress and changes in the moisture content may cause certain apparently well indurated mudrocks to slake, producing a soil-like material. Because many mudrocks are nondurable, they have gained a reputation as problematic soft rocks. Geologists and engineers are confronted with the problem of selecting adequate parameters for accurately evaluating engineering behavior of mudrocks. The use of a single parameter (e.g. grain-size) is never considered to be enough and a combination of several parameters are normally preferred for the classification of mudrocks. Compressive strength, slake durability index, plasticity characteristics, swelling potential, absorption and density are some of the parameters that had been used by several investigators in the past. In order to overcome this problem, considerable research attention has recently been devoted to the use of geological properties (grain size, clay content and clay composition, texture, fracture frequency, degree of lamination, etc.) in conjunction with the engineering characteristics for classification purposes. This paper describes the origin and occurrence of mudrocks, and their different types of classification tests and systems.

Experimental Study on Expansive Soil Improved with Cation Modifier

2011 ◽  
Vol 197-198 ◽  
pp. 1005-1009
Author(s):  
Zhi Qing Li ◽  
Le Fu ◽  
Fang Xie ◽  
Ru Jiao Tan ◽  
Yan Ping Wang ◽  
...  
Keyword(s):  
Yunnan Province ◽  
Void Ratio ◽  
Expansive Soil ◽  
Clay Content ◽  
Dry Density ◽  
Test Results ◽  
Hydrophilic Nature ◽  
Wide Range ◽  
Engineering Cost ◽  
Modified Soil

The improvement of expansive soil with chemical medicine has been concerned by geotechnical engineers. The cation modifier is used to improve the expansive soil in embankment engineering of an express highway in Yunnan province. The modified test results indicate that the hydrophilic nature and swelling-shrinkage properties of samples are changed drastically. The free swelling ratio decrease and the particle size gradation, strength characteristics and hydrological properties of the treated expansive soil are improved by a wide range. The clay content decreases, but the silt content increases. The void ratio decreases sharply, but the fabric becomes more compact. The change of dry density with water content changing is less, but the water stability of modified soil is improved. The indexes are satisfied with the project requests and the engineering cost reduces.

scholarly journals Finite-difference based response surface methodology to optimize tailgate support systems in longwall coal mining

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Satar Mahdevari ◽  
Mohammad Hayati
Keyword(s):  
Compressive Strength ◽  
Response Surface Methodology ◽  
Rock Mass ◽  
Finite Difference ◽  
Longwall Mining ◽  
Support Systems ◽  
Rock Mass Rating ◽  
Slake Durability Index ◽  
Proposed Model ◽  
Durability Index

AbstractDesigning a suitable support system is of great importance in longwall mining to ensure the safe and stable working conditions over the entire life of the mine. In high-speed mechanized longwall mining, the most vulnerable zones to failure are roof strata in the vicinity of the tailgate roadway and T-junctions. Severe roof displacements are occurred in the tailgate roadway due to the high-stress concentrations around the exposed roof span. In this respect, Response Surface Methodology (RSM) was utilized to optimize tailgate support systems in the Tabas longwall coal mine, northeast of Iran. The nine geomechanical parameters were obtained through the field and laboratory studies including density, uniaxial compressive strength, angle of internal friction, cohesion, shear strength, tensile strength, Young’s modulus, slake durability index, and rock mass rating. A design of experiment was developed through considering a Central Composite Design (CCD) on the independent variables. The 149 experiments are resulted based on the output of CCD, and were introduced to a software package of finite difference numerical method to calculate the maximum roof displacements (dmax) in each experiment as the response of design. Therefore, the geomechanical variables are merged and consolidated into a modified quadratic equation for prediction of the dmax. The proposed model was executed in four approaches of linear, two-factor interaction, quadratic, and cubic. The best squared correlation coefficient was obtained as 0.96. The prediction capability of the model was examined by testing on some unseen real data that were monitored at the mine. The proposed model appears to give a high goodness of fit with the accuracy of 0.90. These results indicate the accuracy and reliability of the developed model, which may be considered as a reliable tool for optimizing or redesigning the support systems in longwall tailgates. Analysis of variance (ANOVA) was performed to identify the key variables affecting the dmax, and to recognize their pairwise interaction effects. The key parameters influencing the dmax are respectively found to be slake durability index, Young’s modulus, uniaxial compressive strength, and rock mass rating.

Effects of Laumontite Hydration/Dehydration on Swelling Deformation and Slake Durability of Altered Granodiorite

2020 ◽  
Vol 26 (4) ◽  
pp. 507-516
Author(s):  
Junsong Yan ◽  
Junhui Shen ◽  
Kaizhen Zhang ◽  
Jianjun Xu ◽  
Weifeng Duan ◽  
...  
Keyword(s):  
Axial Strain ◽  
Test Results ◽  
X Ray Diffraction ◽  
Dam Foundation ◽  
Hydro Power ◽  
Slake Durability Index ◽  
Slake Durability ◽  
Dehydration Reactions ◽  
Short Period ◽  
Durability Index

ABSTRACT The mineral laumontite can undergo hydration/dehydration reactions at room temperature. The hydration/dehydration produces a 3 to 6 percent volume change in the unit cell. The effects of laumontite hydration/dehydration on swelling and slake durability were investigated using altered granodiorite containing laumontite from the dam foundation of Yangfanggou Hydro Power Station, Sichuan, China. The occurrence of laumontite in altered rocks was first determined by petrological analysis. Typical samples were then collected for laboratory X-ray diffraction (XRD) analyses, free swelling tests, and slake durability index (SDI) tests. The test results were analyzed to determine the quantitative relationships between laumontite content, maximum axial strain, and slake durability index. We found that hydration of laumontite led to rock swelling. As laumontite content increased, maximum axial strain increased linearly; if water penetrated the rock quickly, swelling occurred over a short period. The hydration/dehydration of laumontite decreased slake durability of the rock; the SDI decreased approximately linearly as laumontite content increased.

scholarly journals State-of-the-Art-Review of Collapsible Soils

2000 ◽  
Vol 5 ◽  
pp. 115 ◽  
Author(s):  
A. A. AL-Rawas
Keyword(s):  
Field Tests ◽  
Clay Content ◽  
Field Testing ◽  
Dry Density ◽  
Foundation Design ◽  
Treatment Methods ◽  
Collapse Potential ◽  
Collapsible Soils ◽  
Different Types ◽  
Compaction Control

Collapsible soils are encountered in arid and semi-arid regions. Such soils cause potential construction problems due to their collapse upon wetting. The collapse phenomenon is primarily related to the open structure of the soil. Several soil collapse classifications based on parameters such as moisture content, dry density, Atterberg limits and clay content have been proposed in the literature as indicators of the soil collapse potential. Direct measurement of the magnitude of collapse, using laboratory and/or field tests, is essential once a soil showed indications of collapse potential. Treatment methods such as soil replacement, compaction control and chemical stabilization showed significant reduction in the settlement of collapsible soils. The design of foundations on collapsible soils depends on the depth of the soil, magnitude of collapse and economics of the design. Strip foundations are commonly used when collapsing soil extends to a shallow depth while piles and drilled piers are recommended in cases where the soil extends to several meters. This paper provides a comprehensive review of collapsible soils. These include the different types of collapsible soils, mechanisms of collapse, identification and classification methods, laboratory and field testing, treatment methods and guidelines for foundation design.

scholarly journals An Experimental Study on the Shear Behaviors of Polymer-Sand Composite Materials after Immersion

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 924 ◽  
Author(s):  
Jin Liu ◽  
Yuxia Bai ◽  
Ding Li ◽  
Qiongya Wang ◽  
Wei Qian ◽  
...  
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Void Ratio ◽  
Dry Density ◽  
Chemical Additives ◽  
Shear Tests ◽  
Direct Shear Tests ◽  
Sand Particles ◽  
Shear Behaviors ◽  
Sand Material

Sand mixed with geotextile/fiber/cement/lime or non-traditional chemical additives to form composite materials is recognized as an effective method for improving the sand properties. In this work, the variation in properties of composite materials after immersion is reported which has rarely appeared in the literature. The focus of this study is to evaluate the shear behaviors of polymer-sand composite material after immersion with direct shear tests. Several factors which may influence the shear behaviors after immersion are analyzed. The results demonstrate that this composite material still has good shear behaviors after immersion when compared to the purely sand material. The shear behaviors are improved with an increment in the curing time, polymer content and sand dry density while there is a decrease in the shear behaviors with increasing immersion time. The interaction between sand particles and the polymer are analyzed with Scanning Electron Microscope (SEM). The polymer membranes are formed by polymer enwrapping and connected sand particles to build an elastic and viscous structure in the sand that increases the interlocking forces between sand particles and decreases the void ratio of this material. The membranes are softened in water resulting in a decrease in the shear strength. Moreover, other factors affect the shear behaviors by improving the completeness and stability of this structure.

scholarly journals An annotated checklist of the psyllids of California (Hemiptera: Psylloidea)

Zootaxa ◽  
2012 ◽  
Vol 3193 (1) ◽  
pp. 1 ◽  
Author(s):  
DIANA M. PERCY ◽  
ALESSANDRA RUNG ◽  
MARK S. HODDLE
Keyword(s):  
Biological Control ◽  
Species Diversity ◽  
North America ◽  
Key Words ◽  
Pest Species ◽  
Floristic Diversity ◽  
Control Programs ◽  
New Synonym ◽  
Annotated Checklist ◽  
Key Words Biogeography

A revised checklist to the species of Psylloidea (Hemiptera) from California is presented, with information on host plantdata, distributions, introduced and pest species, parasites, parasitoids, and predators, and biological control programs. Thelist includes 164 species, of which six are newly recorded. In total, this comprises a 26% increase in the number of speciesrecorded for California since the last published checklist in 1988. Choricymoza Bliven is a new synonym of PhylloplectaRiley, and 10 species previously in Euphalerus Schwarz are recombined under Nyctiphalerus Bliven. California has therichest native psyllid fauna in North America, and the influence of climatic and floristic diversity on this diversificationis considered. Key words: biogeography, host plant, jumping plant lice, species diversity, pest species.

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