Numerical modelling of the impact crater depth–diameter dependence in an acoustically fluidized target

2003 ◽  
Vol 51 (13) ◽  
pp. 831-845 ◽  
Author(s):  
K. Wünnemann ◽  
B.A. Ivanov
2018 ◽  
Author(s):  
Stefan Hergarten ◽  
Thomas Kenkmann

Abstract. Worldwide erosion rates seem to have increased strongly since the beginning of the Quaternary, but there is still discussion about the role of glaciation as a potential driver and even whether the increase is real at all or an artefact due to losses in the long-term sedimentary record. In this study we derive estimates of average erosion rates on the time scale of some tens of million years from the terrestrial impact crater inventory. This approach is completely independent from all other methods to infer erosion rates such as river loads, preserved sediments, cosmogenic nuclides and thermochronometry. Our approach yields average erosion rates as a function of present-day topography and climate. The results confirm that topography accounts for the main part of the huge variation of erosion on Earth, but also identifies a significant systematic dependence on climate in contrast to several previous studies. We found a fivefold increase in erosional efficacy from the cold regimes to the tropical zone and that temperate and arid climates are very similar in this context. Combining our results to a worldwide mean erosion rate we found that erosion rates on the time scale of some tens of million years are at least as high as present-day rates and suggest that glaciation has a rather regional effect with a limited impact at the continental scale.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hanna Michalak ◽  
Paweł Przybysz

Abstract The paper will analyse and review the experience to date in determining the impact range of implementation of deeply founded structures on the displacement of the subsoil in the vicinity. With the background of these experiences, primarily empirical, the present possibilities of using numerical modelling to forecast the displacements of the terrain surface in various stages of works, that is, execution of deep excavation support systems, excavation-deepening phases with successive adding of struts, construction of underground levels and erection of the above-ground part of the building, will be presented. Based on the results of own research, conclusions on the use of 3D numerical models in spatial shaping and designing the structure of underground parts of new buildings erected in dense urban development will be presented. The characterised 3D numerical models were verified, taking into account the actual results of geodetic measurements of the completed buildings. Determining the range and forecasting the displacements of the subsoil are necessary for the design and implementation of investments due to the need to ensure the safety of erection and use of a new building and the buildings located within the area of influence.


2015 ◽  
Vol 36 (2) ◽  
pp. 17-28
Author(s):  
Lucyna Florkowska ◽  
Jan Walaszczyk

Abstract Numerical modelling is an important tool used to analyse various aspects of the impact of underground mining on existing and planned buildings. The interaction between the building and the soil is a complex matter and in many cases a numerical simulation is the only way of making calculations which will take into consideration the co–existence of a number of factors which have a significant influence on the solution. The complexity of the matter also makes it a difficult task to elaborate a proper mathematical model – it requires both a thorough knowledge of geologic conditions of the subsoil and the structural characteristics of the building. This paper discusses the most important problems related to the construction of a mathematical model of a building-mining subsoil system. These problems have been collected on the basis of many years of experience the authors have in observing the surveying and tensometric deformations of the rock–mass and buildings as well as in mathematical and numerical modelling of the observed processes.


2018 ◽  
Vol 196 ◽  
pp. 01055
Author(s):  
Sławomir Dudziak ◽  
Zofia Kozyra

Dynamic analyses play an important role in the process of designing buildings in the vicinity of transportation routes. The Finite Element Method is the most popular modelling technique, because it allows to simulate the structure response in the higher frequency range properly. However, the results of such analyses depend on many factors and can differ a lot. This paper discusses the impact of the building mass estimation and neglecting or including damping in the analysis on the assessment of influence of vibrations due to traffic on people.


2019 ◽  
Vol 7 (2) ◽  
pp. 459-473 ◽  
Author(s):  
Stefan Hergarten ◽  
Thomas Kenkmann

Abstract. Worldwide erosion rates seem to have increased strongly since the beginning of the Quaternary, but there is still discussion about the role of glaciation as a potential driver and even whether the increase is real at all or an artifact due to losses in the long-term sedimentary record. In this study we derive estimates of average erosion rates on the timescale of some tens of millions of years from the terrestrial impact crater inventory. This approach is completely independent from all other methods to infer erosion rates such as river loads, preserved sediments, cosmogenic nuclides, and thermochronometry. Our approach yields average erosion rates as a function of present-day topography and climate. The results confirm that topography accounts for the main part of the huge variation in erosion on Earth, but also identifies a significant systematic dependence on climate in contrast to several previous studies. We found a 5-fold increase in erosional efficacy from the cold regimes to the tropical zone and that temperate and arid climates are very similar in this context. Combining our results into a worldwide mean erosion rate, we found that erosion rates on the timescale of some tens of millions of years are at least as high as present-day rates and suggest that glaciation has a rather regional effect with a limited impact at the continental scale.


2020 ◽  
Vol 310 ◽  
pp. 00054
Author(s):  
Miroslaw Wieczorek

The paper presents the numerical analysis of the impact of removing a corner column on the behavior of a continuous slab-column structure. The model uses the minimal reinforcement amount compliant with Eurocodes. The basis for numerical modelling was the experimental research of a piece of a slab-column structure with the dimensions of 3.0×3.0 m in column axes. The article includes a detailed description of the assumed conditions of the model support, the method of loading and reading of the results. The paper also compares the obtained results of numerical calculations with experimental results.


2011 ◽  
Vol 3 (2) ◽  
pp. 64-71 ◽  
Author(s):  
Kęstutis Kelevišius ◽  
Jonas Amšiejus ◽  
Šarūnas Skuodis

In most cases, the bearing capacity of the pile under natural conditions can be determined by applying static and dynamic pile tests as well as the numerical modelling of a dynamic test. The integrated business problem is employed for calculating vertical displacements. This integral is calculated using the summing method. In the majority of cases, real pile strength capacity can be investigated referring to the adapted means of testing applying the mathematical model that can calculate static or dynamic investigations. The idealized scheme of a pile test is presented including a hammering system and soil properties. Moreover, information on the analysis and work of the scheme is disclosed. The article also describes pile hammering models and the equation for Smith method improved by Edwards, Holloway, Briaud and Trucker, Rieke and Crowser, ”GRL“, including the advantages and disadvantages of the introduced method. Smith realized the mathematical analysis of wave propagation supported by a real hammer-pile-soil scheme by discretic elements interaction. Basing on this for classical one dimensional method of wave propagation (that is programmed in computer program MW87) the code of the computer program was changed by authors of this article. When using a computer program, an algorithm for an integral equation was created. The introduced algorithm was made for counting experimental displacement the growth of which along the pile was analyzed. All obtained results were compared with the engineering method indicating that diff erence in results made less than 2%. Using computer program MW87, a diff erent distribution of shaft friction along the pile was studied when the total shaft friction in all cases was constant, because, the results of numerical modelling disclosed that the shaft friction of the pile in one diameter above the pile’s toe was larger than that in the middle or at the top. The hammer-pile-soil system was analyzed with reference to the impact of the returning wave at the top of the pile. Wave propagation in the pile is vertical: the first wave moves from the top to the bottom of the pile. When the bottom is reached, impact wave returns to the top of the pile. All information about the pile of the returning wave is useful as then we can analyze the integrity and bearing capacity of the pile. All this information received from the returning wave is integrated and later shown in the scheme where we can see all steps of performed operations. This article investigates soil deformations and these deformations in soil influence for a hammering pile. A pile of 0,8 m in diameter and 3 m in height, which is in sand, is an object of investigation in this article. For calculation purposes, the pile is divided into 20 segments. Changes in velocities and displacements of pile segments during analysis are graphically shown. Aft er calculating tests on pile dynamics considering diff erent masses of hammers, falling heights of hammers, contribution of shaft friction and static resistances of the piles, a nomograme for determining static resistance of the pile was made. The article explains how the use of the nomograme determines static resistance of the pile and what data on conducting a pile test are needed.


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