Rock slope stability analysis using shear strength reduction technique (SSRT) – case histories

Purpose. This study aims to evaluate the slope stability of open pit comprising massive and jointed rock mass. Methods. Mohr-Coulomb yield function (MC) with shear strength reduction technique (SSRT) are incorporated in finite element analysis (FEA) and four different slopes with varying geometry and geological structural features with an ultimate slope angle of 34° are analyzed using the two-dimensional FEA Program RS2D. The first slope comprises blocky rock mass; the second slope has a network of joints parallel to slope face; the third slope has a parallel joint networks dip out the slope face, and the last slope has a cross-joints network. Findings. The critical strength reduction factor (CSRF) indicates whether the slope face is stable (if CSRF ≥ 1) or not. The minimum CSRF of 0.53 (e.g. compared to 0.55 for parallel joints dip out to the slope face, 0.58 for joints parallel to slope face and 0.65 with no joint existed) is obtained with cross-joints network existed. The CSRF (e.g., CSRF = 0.49) reduces when the MC slip criterion is adopted with the jointed rock mass. Originality. This study attempts new stability indicator namely critical strength reduction factor (CSRF) embedded in shear strength reduction technique (SSRT), based on finite element (FEM) to assess the slope of open pit with respect to presence of geological discontinuities. Practical implications. The slope stability of rock mass is significant to design parameters in open pit mines. Unexpected instability is eventually costly, hazardous to personnel/machinery, disrupted to the mining operation and time-consuming. Therefore, this study Provides a methodology for the application of shear strength reduction technique (SSRT) when evaluating the slope stability of open pit mines with respect to existence of geological features. As a result, the mine planners and engineers will be able to know a head of time when and where necessary support is needed.Мета. Дослідження стійкості укосу при відкритій розробці вугільного пласта в умовах твердих і тріщинуватих порід на основі чисельного моделювання. Методика. Функція плинності Мора-Кулона і метод зменшення опору зсуву використані разом з аналізом кінцевих елементів, причому 4 укоси з відмінностями в геометрії та геологічних структурних характеристиках (з оптимальним кутом схилу 34°) проаналізовані за допомогою двомірної програми FEA Program RS2D. Перший укіс представлений бриластою гірської породою, другий укіс покритий сіткою тріщин, паралельних поверхні укосу, третій укіс має паралельні тріщини, перпендикулярні до поверхні укосу, і останній укіс покритий сіткою пересічних тріщин. Результати. Показано, що ступінь стійкості укосу характеризується індексом зменшення критичного опору (ІЗКО) і при ІЗКО ≥ 1 укіс вважається стійким. Встановлено, що мінімальне значення ІЗКО дорівнює 0.53 (0.55 – для паралельних тріщин, перпендикулярних до поверхні укосу; 0.58 – для тріщин паралельних поверхні укосу; 0.65 – при відсутності тріщин) і відповідає укосу, який покритий сіткою пересічних тріщин. ІЗКО зменшується (наприклад, до 0.49), коли зсувне зміщення функції плинності Мора-Кулона застосовується для аналізу тріщинуватих порід. Наукова новизна. Запропоновано індекс зменшення критичного опору в якості нового індикатора стійкості, який є ключовим фактором методу зменшення опору зсуву, заснованого на методі скінченних елементів, і застосовується для виявлення геологічних несуцільностей укосу кар’єру. Практична значимість. Запропоновано метод зменшення опору зсуву при оцінці стійкості схилу в кар’єрах з урахуванням існуючих геологічних особливостей. Стійкість породного масиву є важливим фактором при проектуванні параметрів кар’єрів, а при проектуванні шахт – для вибору місць та способів кріплення.Цель. Исследование устойчивости откоса при открытой разработке угольного пласта в условиях твердых и трещиноватых пород на основе численного моделирования. Методика. Функция текучести Мора-Кулона и метод уменьшения сопротивления сдвигу использованы вместе с анализом конечных элементов, причем 4 откоса с различиями в геометрии и геологических структурных характеристиках (с оптимальным углом склона 34°) проанализированы с помощью двухмерной программы FEA Program RS2D. Первый откос представлен глыбистой горной породой, второй откос покрыт сеткой трещин, параллельных поверхности откоса, третий откос имеет параллельные трещины, перпендикулярные к поверхности откоса, и последний откос покрыт сеткой пересекающихся трещин. Результаты. Показано, что степень устойчивости откоса характеризуется индексом уменьшения критичного сопротивления (ИУКС) и при ИУКС ≥ 1 откос считается устойчивым. Установлено, что минимальное значение ИУКС равно 0.53 (0.55 – для параллельных трещин, перпендикулярных к поверхности откоса; 0.58 – для трещин, параллельных поверхности откоса; и 0.65 – при отсутствии трещин) и соответствует откосу, который покрыт сеткой пересекающихся трещин. ИУКС уменьшается (например, до 0.49), когда сдвиговое смещение функции текучести Мора-Кулона применяется для анализа трещиноватых пород. Научная новизна. Предложен индекс уменьшения критичного сопротивления в качестве нового индикатора устойчивости, который является ключевым фактором метода уменьшения сопротивления сдвигу, основанного на методе конечных элементов, и применяется для выявления геологических несплошностей откоса карьера. Практическая значимость. Предложен метод уменьшения сопротивления сдвигу при оценке устойчивости склона в карьерах с учетом существующих геологических особенностей. Устойчивость породного массива является важным фактором при проектировании параметров карьеров, а при проектировании шахт – для выбора места и способов крепления.The authors acknowledge the support of Rocscience Inc. for getting a free full educational version of RS2D (Rock-Soil two-dimensional finite-element analysis program). The authors are grateful for their support

Effects of oral ginkgo biloba extract on pregnancy complicated by asymmetrically intrauterine growth restriction: a double-blinded randomized placebo-controlled trial

Objectives: to evaluate the effect of oral ginkgo biloba extract (GB)) on asymmetrical intrauterine growth restriction (IUGR). Study Design: A randomized trial conducted at Assiut Women Health on 226 pregnant women with asymmetrical IUGR. The patients randomly received GB extract or placebo for 6 weeks. The main outcome measures were improvement in fetal weight and feto-maternal blood flow. The data were analyzed by Student’s t- test and chi-squared tests. Result: There was a significant increase in the estimated fetal weight in the GB group (3047+ 127 gm) when compared to the placebo group (2734+ 127 gm) (p= Conclusions: GB extract improves placental functions, Doppler indices and fetal weight in pregnancies complicated with IUGR fetuses

Effects of oral ginkgo biloba extract on pregnancy complicated by asymmetrically intrauterine growth restriction: a double-blinded randomized placebo-controlled trial

Objectives: to evaluate the effect of oral ginkgo biloba extract (GB)) on asymmetrical intrauterine growth restriction (IUGR). Study Design: A randomized trial conducted at Assiut Women Health on 226 pregnant women with asymmetrical IUGR. The patients randomly received GB extract or placebo for 6 weeks. The main outcome measures were improvement in fetal weight and feto-maternal blood flow. The data were analyzed by Student’s t- test and chi-squared tests. Result: There was a significant increase in the estimated fetal weight in the GB group (3047+ 127 gm) when compared to the placebo group (2734+ 127 gm) (p= Conclusions: GB extract improves placental functions, Doppler indices and fetal weight in pregnancies complicated with IUGR fetuses

An evolutionary approach to a combined mixed integer programming model of seaside operations as arise in container ports

This paper puts forward an integrated optimisation model that combines three distinct problems, namely berth allocation, quay crane assignment, and quay crane scheduling that arise in container ports. Each one of these problems is difficult to solve in its own right. However, solving them individually leads almost surely to sub-optimal solutions. Hence, it is desirable to solve them in a combined form. The model is of the mixed-integer programming type with the objective being to minimize the tardiness of vessels and reduce the cost of berthing. Experimental results show that relatively small instances of the proposed model can be solved exactly using CPLEX. Large scale instances, however, can only be solved in reasonable times using heuristics. Here, an implementation of the genetic algorithm is considered. The effectiveness of this implementation is tested against CPLEX on small to medium size instances of the combined model. Larger size instances were also solved with the genetic algorithm, showing that this approach is capable of finding the optimal or near optimal solutions in realistic times

Combined quay crane assignment and quay crane scheduling with crane inter-vessel movement and non-interference constraints

Integrated models of the quay crane assignment problem (QCAP) and the quay crane scheduling problem (QCSP) exist. However, they have shortcomings in that some do not allow movement of quay cranes between vessels, others do not take into account precedence relationships between tasks, and yet others do not avoid interference between quay cranes. Here, an integrated and comprehensive optimization model that combines the two distinct QCAP and QCSP problems which deals with the issues raised is put forward. The model is of the mixed-integer programming type with the objective being to minimize the difference between tardiness cost and earliness income based on finishing time and requested departure time for a vessel. Because of the extent of the model and the potential for even small problems to lead to large instances, exact methods can be prohibitive in computational time. For this reason an adapted genetic algorithm (GA) is implemented to cope with this computational burden. Experimental results obtained with branch-and-cut as implemented in CPLEX and GA for small to large-scale problem instances are presented. The paper also includes a review of the relevant literature

Structural Biology of Human H3K9 Methyltransferases

SET domain methyltransferases deposit methyl marks on specific histone tail lysine residues and play a major role in epigenetic regulation of gene transcription. We solved the structures of the catalytic domains of GLP, G9a, Suv39H2 and PRDM2, four of the eight known human H3K9 methyltransferases in their apo conformation or in complex with the methyl donating cofactor, and peptide substrates. We analyzed the structural determinants for methylation state specificity, and designed a G9a mutant able to tri-methylate H3K9. We show that the I-SET domain acts as a rigid docking platform, while induced-fit of the Post-SET domain is necessary to achieve a catalytically competent conformation. We also propose a model where long-range electrostatics bring enzyme and histone substrate together, while the presence of an arginine upstream of the target lysine is critical for binding and specificity. Enhanced version: This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the web plugin are available i

Structural Studies of a Four-MBT Repeat Protein MBTD1

The Polycomb group (PcG) of proteins is a family of important developmental regulators. The respective members function as large protein complexes involved in establishment and maintenance of transcriptional repression of developmental control genes. MBTD1, Malignant Brain Tumor domain-containing protein 1, is one such PcG protein. MBTD1 contains four MBT repeats.We have determined the crystal structure of MBTD1 (residues 130-566aa covering the 4 MBT repeats) at 2.5 A resolution by X-ray crystallography. The crystal structure of MBTD1 reveals its similarity to another four-MBT-repeat protein L3MBTL2, which binds lower methylated lysine histones. Fluorescence polarization experiments confirmed that MBTD1 preferentially binds mono- and di-methyllysine histone peptides, like L3MBTL1 and L3MBTL2. All known MBT-peptide complex structures characterized to date do not exhibit strong histone peptide sequence selectivity, and use a "cavity insertion recognition mode" to recognize the methylated lysine with the deeply buried methyl-lysine forming extensive interactions with the protein while the peptide residues flanking methyl-lysine forming very few contacts [1]. Nevertheless, our mutagenesis data based on L3MBTL1 suggested that the histone peptides could not bind to MBT repeats in any orientation.The four MBT repeats in MBTD1 exhibits an asymmetric rhomboid architecture. Like other MBT repeat proteins characterized so far, MBTD1 binds mono- or dimethylated lysine histones through one of its four MBT repeats utilizing a semi-aromatic cage.This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the web plugin are available in Text S1

A highly mutagenised barley (cv. Golden Promise) TILLING population coupled with strategies for screening-by-sequencing

Background:We developed and characterised a highly mutagenised TILLING population of the barley (Hordeum vulgare) cultivar Golden Promise. Golden Promise is the 'reference' genotype for barley transformation and a primary objective of using this cultivar was to be able to genetically complement observed mutations directly in order to prove gene function. Importantly, a reference genome assembly of Golden Promise has also recently been developed. As our primary interest was to identify mutations in genes involved in meiosis and recombination, to characterise the population we focused on a set of 46 genes from the literature that are possible meiosis gene candidates. Results:Sequencing 20 plants from the population using whole exome capture revealed that the mutation density in this population is high (one mutation every 154 kb), and consequently even in this small number of plants we identified several interesting mutations. We also recorded some issues with seed availability and germination. We subsequently designed and applied a simple two-dimensional pooling strategy to identify mutations in varying numbers of specific target genes by Illumina short read pooled-amplicon sequencing and subsequent deconvolution. In parallel we assembled a collection of semi-sterile mutants from the population and used a custom exome capture array targeting the 46 candidate meiotic genes to identify potentially causal mutations. Conclusions:We developed a highly mutagenised barley TILLING population in the transformation competent cultivar Golden Promise. We used novel and cost-efficient screening approaches to successfully identify a broad range of potentially deleterious variants that were subsequently validated by Sanger sequencing. These resources combined with a high-quality genome reference sequence opens new possibilities for efficient functional gene validation.Miriam Schreiber, Abdellah Barakate, Nicola Uzrek, Malcolm Macaulay, Adeline Sourdille, Jenny Morris, Pete E. Hedley, Luke Ramsay and Robbie Waug