Domestic and international best practice in research and testing glass for load-bearing structures of buildings

The present work provides an overview and analysis of scientific, technical, regulatory, and methodical Russian and foreign literature regarding using glass as a material for load-bearing structures of buildings. In the absence of design standards, an experimental study of usually one or two samples is necessary each time glass structure is used; however, this is insufficient to determine the distinct pattern of material performance. Since jointing the glass structures has been rarely studied, the number of tests is minimal, thus preventing establishing the unambiguous material operation and its calculated physical and mechanical characteristics. The article considers and evaluates the test results of glass structures obtained by various methods. The particular values of ultimate stresses and deformation modulus lie in a wide range. The technology, manufacturing process, and starting materials have a significant influence on the characteristics of glass, including multilayer glass. This article stresses the need for developing regulatory technical and methodical documents, the design and testing standards for glass structures and their jointing. It is necessary to classify load-bearing glass structures by various criteria.

Effect of the dewatering on the surrounding terrains during the construction of Metrostation 9-III of the Sofia Metropoliten

The international practice often faces significant settlements of terrains and structures due to dewatering. This study presents of the dewatering impact during the construction of Metrostation 9-III from the Sofia Metropoliten on the surrounding terrains and buildings. The subsidences are quantified for specific values of the soil deformation modulus and varying values of the soil hydraulic conductivity.

A new de Sitter solution with a weakly warped deformed conifold

We revisit moduli stabilisation for type IIB flux compactifications that include a warped throat region corresponding to a warped deformed conifold, with an anti-D3-brane sitting at its tip. The warping induces a coupling between the conifold’s deformation modulus and the bulk volume modulus in the Kähler potential. Previous works have studied the scalar potential assuming a strong warping such that this coupling term dominates, and found that the anti-D3-brane uplift may destabilise the conifold modulus and/or volume modulus, unless flux numbers within the throat are large, which makes tadpole cancellation a challenge. We explore the regime of parameter space corresponding to a weakly-but-still warped throat, such that the coupling between the conifold and volume moduli is subdominant. We thus discover a new metastable de Sitter solution within the four-dimensional effective field theory. We discuss the position of this de Sitter vacuum in the string theory landscape and swampland.

Influence of soil moisture on the deformation properties of soil-crushed stone samples during compression

Introduction. The purpose of the article is to determine the dependence of the influence of soil moisture and the content of crushed stone in a soil-crushed stone sample on the secant modulus of deformation under uniaxial compression. The need for such a mathematical model is necessary in order to introduce correction factors to the values of the stamped deformation moduli of the gravel layer calculated from test data delivered at other soil moisture conditions, e.g. for flume or road tests during a non-calculated period of the year.Materials and methods. Cylindrical samples with a height of 20 cm and a diameter of 10 cm were made to perform tests using a large standard sealing device. The content of crushed stone of a mixture of fractions of 5-10 and 10-20 mm varied in the samples. The methods of saturation of samples with water and their testing by uniaxial compression are given. The rules for processing the experimental results are described, which include: correction of the initial part of the graphical dependence of deformation from pressure and statistical processing of the results. The analysis of methods for calculating the deformation modulus, which are classified into three types, is performed: secant module, tangent module and piecewise linear module. Based on this analysis, a method for calculating the deformation modulus of a soil-crushed stone sample under uniaxial compression is justified.Results. The results of experimental determination of the deformation characteristics of soil-crushed stone samples under uniaxial compression are presented. A mathematical model of the dependence of the deformation modulus of a soil-crushed stone sample from the soil moisture and the content of crushed stone used in the soil-crushed stone mixture is obtained.Discussion and conclusions. Recommendations are given on the application of the research results for the development of an album of standard constructions of road pavement of the lowest type in the districts of the Omsk region.

Research on the Inversion Method and Application of Random Mechanical Parameters for Arch Dam and Its Nearby Mountain Structure

First, prior distribution of the mechanical parameters of arch dam body and its nearby mountain rock mass was determined according to the meso-modelling of dam concrete and test data of its nearby mountain rock mass, and a finite element model of the arch dam and its nearby mountain was established. Based on Bayesian theory, random inversion objective function was established. Afterwards, inversion analysis of mechanical parameters was conducted with Differential Evolution Adaptive Metropolis (DREAM(SZ)) on the basis of Markov chain random theory, for the inversion of random distribution parameters of the elasticity modulus of dam concrete and overall deformation modulus. This method was applied to some high-arch dam project, and it was verified to be effective by the results.

Deformation Development Mechanism in a Loess Slope With Seepage Fissures Subjected to Rainfall and Traffic Load

Loess landslides induced by rainfall and traffic load are significant hazards during the construction and operation of highways in many loess-covered areas. Studies of the deformation and stability of loess slopes with seepage fissures are limited. In the study, a case study of the Yangpoyao loess slope with seepage fissures in China’s Loess Plateau was conducted to reveal the deformation development mechanism and assess the landslide hazards of such fissured loess slopes. First, the hydraulic-mechanical properties of the Q2 loess were investigated through experiments, and the mathematical expressions of the relationships between various mechanical parameters and water content were fitted, indicating that the mechanical parameters, such as cohesion, angle of internal friction, and deformation modulus, vary in a quasi-linear manner with the water content. Then, a new numerical method was proposed to simulate the mechanical behaviours of the loess considering its water sensitivity and transverse isotropy, where the water sensitivity was considered through the implementation of the mathematical expressions of the hydraulic-mechanical relationships, and the transverse isotropy was considered by the modified constitutive model that combined the logics of transversely elastic model and a ubiquitous-joint model. Finally, the deformation development mechanism of the fissured loess slope under rainfall and traffic load was revealed by using the proposed method. The roles of the rainfall and traffic load in the fissure propagation and deformation development process of the slope were explored, and some stabilisation measures are recommended for the prevention of its failure. The proposed method and findings arising therefrom may provide references for future studies of the stability and landslide hazard assessment of fissured loess slopes.