Optimization and evaluation of structural and shielding concrete for IFMIF-DONES

The aim of this study was to optimize and evaluate structural and shielding concrete for the IFMIF-DONES building. An ordinary concrete of lime-dolomite aggregate from local sources has been chosen for structural concrete and magnetite aggregate was chosen for heavy-weight radiation shielding. The reference for concrete materials design was the one used in the ITER project. After investigations of raw materials, a group of pre- batches were prepared and technical properties – density of compressive strength, were measured. Finally, two compositions have been elaborated – one for structural concrete of density 2.5 g/cm$^3$ and the second for radi- ation shielding concrete of density 3.9 g/cm$^3$. Then a set of 50 × 50 × 5 cm$^3$ slabs were prepared and sent to the Nuclear Physics Institute of the CAS in the Czech Republic for shielding mock-up experiments. Also the other technical properties like E-modulus, bending strength etc. have been determined. Additionally, radiation shielding efficiency has been calculated based on atomic composition

Secondary consolidation modelling by using rheological schemes

The paper presents the possibility of the secondary consolidation modelling in soil mechanics by using rheological schemes. Non-elastic rheological models represent time-dependent behaviour of the soil skeleton and should be expressed by appropriate constitutive relationships in the form of ordinary differential equations. On the other hand, the primary consolidation phenomenon caused by dissipation of the excess pore pressure is modelled by applying the well-known formulation proposed by Terzaghi and expressed by the partial differential equation. The resulting initial boundary value problem was solved numerically for three selected rheological schemes. Algorithms implemented in Mathematica were used for this purpose

Prediction of Structural Performance of Vinyl Ester Polymer Concrete Using FEM Elasto-Plastic Model

This paper presents the methodology for predicting the mechanical performance of structural elements made of polymer concrete (PC). A vinyl ester polymer concrete composition and the results of experimental studies to determine the basic mechanical properties of the material are presented. Following the strategy for sustainable development in the building industry, the material cost of polymer concrete was lowered by reducing the consumption of raw materials and the partial replacing of the microfiller fraction with recycled waste products—calcium fly ash. An accurate computational model enabling stress analysis is a convenient way to verify the suitability of PC as a construction material in structural applications. Due to difficulty in deriving an accurate analytical formula, numerical approximation (finite element method) was used as a method for solving the problem. Constitutive modeling of PC is a very important aspect of the strength calculations and here it was done within the framework of elasto-plasticity. Numerical evaluation of the static bearing capacity of PC manhole covers is shown as an example of the proposed FEM methodology. The results of computer simulations were compared with laboratory tests. Finally, the adequacy of the numerical modeling for testing new construction and material improvements is discussed. The study showed that the concrete damaged plasticity material model can be effectively used for the description of PC mechanical behavior

Secondary consolidation modelling by using rheological schemes

The paper presents the possibility of the secondary consolidation modelling in soil mechanics by using rheological schemes. Non-elastic rheological models represent time-dependent behaviour of the soil skeleton and should be expressed by appropriate constitutive relationships in the form of ordinary differential equations. On the other hand, the primary consolidation phenomenon caused by dissipation of the excess pore pressure is modelled by applying the well-known formulation proposed by Terzaghi and expressed by the partial differential equation. The resulting initial boundary value problem was solved numerically for three selected rheological schemes. Algorithms implemented in Mathematica were used for this purpose

Analysis of stability of railway embankment including horizontal forces in light of Eurocode

The subject of this paper is analysis of the influence of horizontal forces estimated on the basis of Eurocode on the stability of an exemplary railway embankment located in the horizontal curve. The work begins with an overview of the methods for determining the earthworks stability. The methods are presented along with a reference to the recommendations contained in Eurocode 7. On the basis of the Eurocode, the loads acting on the analyzed embankment are presented together. In addition to the standard vertical interactions (from the rolling stock, the weight of the track structure and ground), the calculations also take into account horizontal forces caused by: wind forces on rolling stock, centrifugal forces and nosing force of the rolling stock as well as thermal stresses in the rails. Next, there are 15 load combinations calculated according to the Eurocode guidelines. At the end of the work the values of safety factors of the embankment obtained by shear strength reduction method are presented. The obtained results show a significant influence of horizontal forces calculated on the basis of the Eurocode on the stability of the railway embankment analyzed in the work

A Novel Approach to the Analysis of the Soil Consolidation Problem by Using Non-Classical Rheological Schemes

The paper presents classical and non-classical rheological schemes used to formulate constitutive models of the one-dimensional consolidation problem. The authors paid special attention to the secondary consolidation effects in organic soils as well as the soil over-consolidation phenomenon. The systems of partial differential equations were formulated for every model and solved numerically to obtain settlement curves. Selected numerical results were compared with standard oedometer laboratory test data carried out by the authors on organic soil samples. Additionally, plasticity phenomenon and non-classical rheological elements were included in order to take into account soil over-consolidation behaviour in the one-dimensional settlement model. A new way of formulating constitutive equations for the soil skeleton and predicting the relationship between the effective stress and strain or void ratio was presented. Rheological structures provide a flexible tool for creating complex constitutive relationships of soil

Using Electrical Resistivity Tomography (ERT) as a tool in geotechnical investigation of the substrate of a highway

Geo log i cal and geotechnical en gi neer ing field tests, like struc ture drillings and dy namic (DPL, DPSH) or static probing (CPT), are con sid ered for a fun da men tal source of in for ma tion about soil and wa ter en vi ron ments. Since Eurocode 7 has been in tro duced, it has be come more com mon to use also dilatometers (DMT) or pres sure me ters (PMT). Re sults ob tained us ing all the men tioned tests are al ways of a dis crete na ture – in for ma tion is pro vided in cer tain points in the field. How ever, they de ter mine the ba sis for cre at ing spa tial mod els of geo log i cal struc ture and geotechnical con di - tions of a sub stra tum. The range and num ber of in ves ti ga tions con ducted (in clud ing drill ing, prob ing and lab o ra tory tests) in flu ence pre ci sion, in which a geo log i cal struc ture is iden ti fied and thus, also af fect prob a bil ity of com pat i bil ity be tween spa tial model and real geo log i cal con di tions of a sub stra tum. In the pa per, re sults of non-in va sive elec tri cal re sis tiv ity to mog ra phy (ERT) method are pre sented, com pris ing 2-di men sional im age of a soil me dium re sis tance. Elec tri cal re sis tance is a pa ram e ter that re flects di ver si fi ca tion of a soil me dium, con sid er ing its lithological as pect. In ad di tion, when com bined with drill ing re sults, it can be used to ac cu rate de ter mi na tion of bound aries be tween soil lay - ers. Car ry ing out of ERT tests in the field dur ing ex press way con struc tion con trib uted to iden ti fi ca tion of weak, low-strength soils like or ganic soils (peat, aggradated mud) and of soft con sis tency co he sive soils. These kinds of soil are the main cause for un ac cept able de for ma tions ap pear ing in the new road en gi neer ing struc ture

A Novel Approach to the Analysis of the Soil Consolidation Problem by Using Non-Classical Rheological Schemes

The paper presents classical and non-classical rheological schemes used to formulate constitutive models of the one-dimensional consolidation problem. The authors paid special attention to the secondary consolidation effects in organic soils as well as the soil over-consolidation phenomenon. The systems of partial differential equations were formulated for every model and solved numerically to obtain settlement curves. Selected numerical results were compared with standard oedometer laboratory test data carried out by the authors on organic soil samples. Additionally, plasticity phenomenon and non-classical rheological elements were included in order to take into account soil over-consolidation behaviour in the one-dimensional settlement model. A new way of formulating constitutive equations for the soil skeleton and predicting the relationship between the effective stress and strain or void ratio was presented. Rheological structures provide a flexible tool for creating complex constitutive relationships of soil

One-Dimensional Computational Model of Gyttja Clay for Settlement Prediction

One of the most important subjects of geomechanics research is finding mathematical relationships which could correctly describe behavior of the soil under loading. Safety of every engineering structure depends strongly on accuracy and correctness of this description. As laboratory tests show, macroscopic properties of soil are complicated. Therefore, working out appropriate load-settlement relationships is considered to be a very difficult geomechanics tasks to solve. A majority of constitutive models proposed to date concern mineral soils and there is very little research related to modelling organic soil behavior under loading. In case of organic soils, due to their very complicated and composite structure, constitutive models are often formulated empirically based on laboratory tests of particular soils. The authors of this paper propose a 1-D rheological structure which accounts for complex behavior of soil related to the settlement process. The model simulates immediate reversible elastic settlement and plastic soil deformation as well as primary and secondary (creep effect) consolidation. Material parameters of the model were determined by a curve fitting procedure applied for a natural scale settlement test of plate foundation. The test was carried out in soil conditions connected with Eemian geological structure of Warsaw, i.e., Eemian glacial tunnel valley in Warsaw called Żoliborz Glacial Tunnel Valley filled with organic soils being up to 20 metres thick. This area has lately become an object of interest of investors as a site for building construction

One-Dimensional Computational Model of Gyttja Clay for Settlement Prediction

One of the most important subjects of geomechanics research is finding mathematical relationships which could correctly describe behavior of the soil under loading. Safety of every engineering structure depends strongly on accuracy and correctness of this description. As laboratory tests show, macroscopic properties of soil are complicated. Therefore, working out appropriate load-settlement relationships is considered to be a very difficult geomechanics tasks to solve. A majority of constitutive models proposed to date concern mineral soils and there is very little research related to modelling organic soil behavior under loading. In case of organic soils, due to their very complicated and composite structure, constitutive models are often formulated empirically based on laboratory tests of particular soils. The authors of this paper propose a 1-D rheological structure which accounts for complex behavior of soil related to the settlement process. The model simulates immediate reversible elastic settlement and plastic soil deformation as well as primary and secondary (creep effect) consolidation. Material parameters of the model were determined by a curve fitting procedure applied for a natural scale settlement test of plate foundation. The test was carried out in soil conditions connected with Eemian geological structure of Warsaw, i.e., Eemian glacial tunnel valley in Warsaw called Żoliborz Glacial Tunnel Valley filled with organic soils being up to 20 metres thick. This area has lately become an object of interest of investors as a site for building construction