Miroslav Todorov | University Of Architecture (original) (raw)

Conference Presentations by Miroslav Todorov

СЪДЪРЖАНИЕ 1 Земната механика като дял от механиката. Историческо развитие, предмет и задачи. Ска... more СЪДЪРЖАНИЕ 1 Земната механика като дял от механиката. Историческо развитие, предмет и задачи. Скали и почви. Земна основа. Процеси, развиващи се в повърхностните слоеве на земната кора от гледна точка на строителния инженер. Тектонски процеси и земетресения, високи и приливни вълни ..

Pipeline systems are an integral part of modern human activity for much of the accompanying proce... more Pipeline systems are an integral part of modern human activity for much of the accompanying processes of lifestyle and industry. The design and construction of underground facilities solves one major problem-improving the quality of life by deploying the systems near the consumer, without intruding on the human environment. The necessity for more efficient behavior prognosis and evaluation as well as better design of buried pipelines during and after various actions (including geologic and seismic hazards) is directly related to the knowledge of their working mechanism, while aiming to prevent incidents which impact the human life. A number of additional parameters describing the conditions, behavior and effects of the pipeline system, going beyond the conventional Eurocode methods, is a requirement for the scope of this study. This study covers a comprehensive research system based on laboratory and in situ techniques, numerical analyses and the creation of interaction parameters of a buried pipe with soil massif in dynamic situations. Laboratory analyses were conducted in a laboratory triaxial state with cyclic shear strains (M. Todorov, 2013). All parameters that were defined by constitution models-Mohr-Coulomb, Hardening soil model, Modified Cam-Clay based in a Plaxis software were traced. In the final phase of the publication (Part 2) the implementation and evaluation of the formulated parameters and results of the study are demonstrated.

The operating conditions of the buried pipe system require consideration of three main elements o... more The operating conditions of the buried pipe system require consideration of three main elements of a deterministic limit states analysis carried out by experimental or analytical techniques (Eurocode). In the prognosis analyses (reliable and workable), the complex of external and internal impacts for the system is a first step of limit states estimation (A-EN1990). The second element (M-material parameters)-investigation of the material properties of the system inextricably related to the model. The third element (R-resistance) of deterministic analysis is the most delicate part of the study of any limit state. It poses a significant challenge to creative thinking and requires a reasonable combination of the first two elements to formulate a system model. The investigation focuses on the composition of three-dimensional discrete models based on the bearing capacity of the ground strata. Here, the bearing capacity factors are determined in the general context of geometrical and material characteristics as a function of both changes of soil mass strains and as a result of the degradation of the entire system's stiffness. This allows models to be used in conditions developed in slow movements conditions, such as landslides. These model interpretations have been compared with well-known solutions (O'Rourke and Jeon, 1999) and are evaluated in example solutions in a frame and solid model using both modal analysis and timedependent displacement surface functions.

Landslide processes are a distinct phenomenon with a huge impact on human way of life. Those grav... more Landslide processes are a distinct phenomenon with a huge impact on human way of life. Those gravitational movements in the upper layers of the crust can have a dramatic effect in river valleys, coastal regions and mountainous terrains. The reasons for their existence and development lie in naturally occurring processes in the lithosphere and the atmosphere and large-scale human activity. Investigating various natural and anthropogenic phenomena is vital, with attention to climate change processes. In the report of the European Commission (2012) an alarming level of erosion and abrasion is observed, with more than 630 000 areas with landslide processes. According to MRRB in Bulgaria there are near 2000 zones with active movements. The current investigation focuses on a fragment of the Bulgarian coast prone to landslide that was researched in 2017. The first registered movements date back to 2010. Characterizing for this case is the relatively quick developments of the movements which affect urban areas. This publication revolves around a complex engineering investigation, which provides an understanding how and why activation processes in the researched zone form, while using well-known proven methods. The used techniques for investigation focus on usability issues, as well as on the opportunity to corelate different sets of data, gather important information and reinforce it with monitoring. The focus here is on these three combined steps: information, prediction, monitoring.

Miroslav Todorov, 2013

При голяма част от архитектурните паметници носещата конструкция е формирана от каменни или тухле... more При голяма част от архитектурните паметници носещата конструкция е формирана от каменни или тухлени зидарии - основи, стени, пиластри, сводове, купoли и др. От съвременна гледна точка този вид конструкции са чувствителни към деформации и динамични въздействия. Практиката показва, че често при подобни сгради се наблюдават значителни повреди – пукнатини, обрушвания, разхлабвания и др., които застрашават както паметника, така и сигурността на посетителите. Това налага специално внимание към методи, технически похвати и технологии за усилване и възстановяване, достатъчно надеждни и в същото време щадящи и предпазващи от разрушение паметника.
В доклада се разглежда приложението на инжекционните методи при усилване и възстановяване на зиданите конструкции. Отделено е внимание на проучването на геоложката формация, дефектите и повредите, техническото състояние, технологичните условия на площадката и моделирането на механичното поведение при различни натоварвания и въздействия. Тези особености са илюстрирани с примери на конкретни проектни решения.

M. Todorov, 2018

Дълбокото фундиране, като отделен тип фундаментна конструкция, се характеризира с трансфер на ене... more Дълбокото фундиране, като отделен тип фундаментна конструкция, се характеризира с трансфер на енергия от конструкцията към земната основа. При циклични въз-действия се наблюдават характерни особености в поведението на конструкцията и про-мяна на напрегнато-деформирано състояние на почвата и на механичните ѝ свойства.
През изминалите няколко десетилетия са използвани редица методики за решение на проблема на взаимодействието конструкция-земна основа и в частност конструкция- пилот. Числените методи изискват да се отдели внимание на дефинициите, описващи модела на взаимодействие. Многопараметричнoто взаимодействие налага допълване на аналитичните подходи с емпирични сравнения. Настоящите изследвания целят постигането на по-ясни и точни дефиниции за прилагане на прогнозните аналитични техники.

ISBN 978- 619-7408-28-7, 2017

The modern life and industrialization with their great impact and large scale of influence genera... more The modern life and industrialization with their great impact and large scale of influence generates a colossal amount of waste products. Not only that they have huge physical volume but they also cause many short and long term effects on the nature, human way of life and all processes on the planet. The waste products' concentration in specific zones leads to conditions which makes them uninhabitable.
The construction of landfills for industrial solid waste follows the modern requirements for disposing, encapsulating and on-site environmental monitoring. Main problem with those facilities is the preservation of the integrity of isolation screens. The integrity of the installation is sensitive to the deformations of the ground base of the landfill and in many cases it is nearly impossible to observe. In such cases using monitoring methods with technical equipment is an expensive and unreliable source of information due to the locality of the investigation spots. The development of the hypothesis with analytical forecasting techniques is a necessary measure. The Geotechnical studies cover the analysis of expected settlement usually for 50 years period.
In the present study a great amount of data, consisted of impressive statistical information on both physical and mechanical properties of the natural soil types of the massif and of the depot's body has been used. The data were used for quantitative analysis of long term deformations with the usage of two parallel calculation models. The first one based on the well-known Terzaghi’s [5] one dimensional consolidation solution and the second one – on a two dimensional, created with Plaxis software.
The comparison (of the two separate groups) of the results gives us answers and yet raises questions, which can be answered with the usage of full-scale theoretical-observational study.

DOI 10.14455/ISEC.res.2016.42, 2016

In practice, in many cases using combination of piles and large-slabs could be observed technolog... more In practice, in many cases using combination of piles and large-slabs could be observed technological and structural defects before the start of their operation. These defects are dictated by the complex interaction between piles system and thin raft slabs. In order to establish the causes of defects can be imposed a wide range of studies covering research on the ground, the reinforced concrete structural elements and materials (piles and raft), the technology performance and others. In this study in order to identify the causes of defects are used a series of research methods for determining the properties of materials, environmental conditions and computational models to describe the interaction between ground and upper structure. With this set of methods are established causes and selected measures for appropriate reconstruction. The scope of these measures consists in the use of a combination of hardening by injection of the ground under the contact base of raft. With grouting the aims are to improve the skin friction and end bearing resistance of the piles. In the complex decision are sought the approaches to keep the completed structures - piles and raft. The focus of this work is to improve the interaction of the pile-raft system and ground base at the expense of reducing the load on piles. In this case, the geological formation, represented by Paleogene sediments with alternating layers of hard clay and clay sandstones largely supports the realization of the design measures.

ISSN: 2348-4802, 2013

Reinforced concrete structures in the mass practice of construction have been used for more than ... more Reinforced concrete structures in the mass practice of construction have been used for more than a century. This fact presents challenges for the construction engineer, requiring study of the conditions and assessment of efficiency of the constructions. Especially relevant is the question what is the bearing capacity of the elements and how reliable is the future exploitation of the construction as a whole. In Bulgaria the reinforced concrete has been used since the beginning of 20th century. The first structural concrete was used by the Italian Arnoldo Zocchi in 1903 for the creation of monument of the Emperor Alexander the Second. During the first three-four decades of the 20th century (the second period) the reinforced concrete structures are successfully implemented in housing and community construction. Most of the community and housing buildings of this period already have reinforced concrete bearing skeleton. The third main period of use of steel reinforced concrete constructions is after the World War II. During this period the practice of mass usage of prefabricated steel reinforced concrete constructions is enforced in the Eastern block. Nowadays a big part of the buildings of the Bulgarian industries consists of monolithic and prefabricated reinforced concrete constructions. The results of 70-80 years of exploitation of these buildings and the requirements, enforced by the modern new functions create new tasks for the structures. All these features of the buildings require from the construction engineer knowledge of the study and use of different technological methods of reconstruction.

ISBN-10: 981-07-5354-2, 2013

A number of testing is applied for determining the mechanical properties of soils. Well-known tec... more A number of testing is applied for determining the mechanical properties of soils. Well-known techniques are connected with Casagrande and Shannon; Roscoe; Hardin and Richard (1963); Drnevich, Hall and Richard (1967); Stokoe and Hoar (1978) and others. The analysis of the capabilities of the known devices for dynamic testing conceived the idea for developing of a device that would allow the determination of the mechanical properties as a function of cyclic load. The choice of the type of load has been made on the basis of the analysis of the stress strain condition of the soil under cyclic action. Soils in nature are subjected to multicomponent impact, the direction of the main stresses being inconstant during the loading process. The main reason that provoked the development of a device was the search of a direct method for determining of the mechanical characteristics during cyclic load that can be used for proper definition of some known soil models such and “Mohr-Coulomb” and the Hardening Soil Model. With respect of the aforesaid, the construction of a new device in three axial conditions has been sought, that is based on classicWykeham Farrance device. The application of this modification allowed determination of parameters that take into account the change in the hardness of the system during loading and determination of sufficient number of parameters for defining of the issue soil models.

Missouri University of Science and Technology, International Conference on Case Histories in Geotechnical Engineering, Apr 2013

Bulgaria is a country with rich historical heritage and cultural diversity. The protection and co... more Bulgaria is a country with rich historical heritage and cultural diversity. The protection and conservation of cultural and historical monuments is vital to preserving the national identity of Bulgarians, the relationship with the land and traditional culture as an essential part of his life and means of survival. It should be noted Bulgarian modest contribution to the preservation of 7 (according to UNESCO) cultural monuments and two nature reserves listed as World Heritage.
In the center of the Bulgarian capital - Sofia are located over 1400 cultural and historical monuments that highlight the civilizational and cultural outlook of the capital of Bulgaria. In terms of its rich heritage Sofia has a unique resource of complex nature, characterized by:
High cultural value of individual layers historic and outstanding examples of architectural and building ensembles of the era of ancient and medieval periods, and samples of construction and architecture of the nineteenth and twentieth centuries;
The rich historical stratification of the environment is predetermined by the interaction between the West and the Orient in a European cultural crossroads, expressed with style, religious and ethnic pluralism.
All these features and wealth of construction periods and techniques pose specific requirements on construction techniques for decisions on conservation and restoration.This work presents some specific construction design in terms of approaches that resolve fundamental problems. These approaches are supported by rapidly evolving technologies in the building using various composite materials, taking into account the specific requirements of the treated material.

Non-Cracking Techniques For Grouting, 2017

Techniques for improving the ground base have been used since ancient times. The need of the geot... more Techniques for improving the ground base have been used since ancient times. The need of the geotechnical engineer to use zones with weak (cracked or high porosity) soil poses new, increasingly complicated problems. The solutions must consider requirements for the materials used and restrictions over the invasion. The use of natural (inorganic) materials is an approach resulting from the low speed of the change of the properties. The insignificant effect of the environment on the properties of the materials to be grouted is unquestionable. Here we should consider a number of factors connected with the anthropogenic conditions. An important aspect in the choice of materials is the expected positive changes in the structure and properties of the natural materials - improvement of soil skeleton structure, preservation of the migration of water, filling saturation, decreasing the consolidation deformability and others. The use of techniques for grouting with relatively small influence over the structure and properties of the natural materials requires certain basic mechanical parameters. Here we should pay attention to the scale of the interventions as a whole, the effect of which is considerably smaller than in usual techniques for different deep foundations. Another important aspect of these techniques is the economic effect, which creates conditions for a number of optimizations concerning the use of small-scale resources, by-products (colloidal clay, flay ash, lime, gypsum), small quantities of waste products, short periods for realization and others.

Books by Miroslav Todorov

ISBN 978-619-91513-0-3, 2020

Необходимостта от по-ефективно прогнозиране, проектиране и оценка на поведението на вкопаните тръ... more Необходимостта от по-ефективно прогнозиране, проектиране и оценка на поведението на вкопаните тръбопроводи по време и след различни въздействия е свързана с опознаване на експлоатационните качества и недопускане на инциденти с широко влияние върху човешкия живот. Редица параметри, описващи въздействията, състоянието и поведението на тръбопроводната система и обграждащата среда (почвения масив, в който е положена) изискват обхват на проучванията, които се разпростират отвъд конвенционалните разглеждания. Потенциалните вредни влияния върху човешката среда изискват от преносните тръбопроводни системи запазване на функционалността им по време и след експлоатационни, аварийни, климатични, геодинамични процеси и антропогенни въздействия.
Анализът на натоварванията и въздействията формира един от основните елементи от процесите на прогнозиране (проектиране) и поставя условия към изграждането и експлоатацията (контрола) на тръбопроводните системи.

ISBN 978-619-91513-1-0, 2020

Представените в монографията примери са предмет на проектни разработки, в които авторът е приложи... more Представените в монографията примери са предмет на проектни разработки, в които авторът е приложил комбинация от прогнозни техники за изследване на деформациите в дисперсна среда. Представените примери, въпреки, че са реферирани към стандарти и нормативи, те засягат елементи, които в системата стандарти Eurocode се определят като необходими за детайлно разглеждане от инженера. Чрез подходите и последващите наблюдения на параметрите за мониторинг се проследява един кратък период от проектния експлоатационен срок. В този смисъл заключенията представят качествени тенденции в разглежданите методи за прогноза на деформациите в земната основа и други дисперсни конструкции като основен елемент от оценката на дълготрайността на конструкциите.
Тези разработки са дело на опита на автора, базирани на използването на конвенционални и оригинални средства за изследване на дисперсната среда, непрекъсната съпоставка на известните техники (аналитични решения) и прилагането на конститутивните модели в среда на Plaxis.

ISBN 978-954-724-082-7, 2015

Учебникът е предназначен за обучение на студентите по специалност „Строителство на сгради и съоръ... more Учебникът е предназначен за обучение на студентите по специалност „Строителство на сгради и съоръжения“, с магистърска степен на обучение в Университета по архитектура, строителство и геодезия – гр. София. С него се покрива обема по дисциплината „Фундиране“, изучавана в магистърския курс на обучение. Той може да се използва и от студентите от всички инженерни специалности на УАСГ, и като практическо помагало, с отчитане на изискванията на нормативната база. Тук са представени и някои решения, използвани при проектирането на различни фундаментни конструкции.
В учебника са разгледани основните концепции за провеждане на изчислителен анализ, необходим за доказване на механизмите за разрушение и сляганията при фундаментните конструкции.

ISBN 978-954-724-081-0, 2015

Настоящият учебник е предназначен за обучение на студентите по специалност „Строителство на сград... more Настоящият учебник е предназначен за обучение на студентите по специалност „Строителство на сгради и съоръжения“ и всички други специалности с магистърска степен на обучение в Университета по архитектура, строителство и геодезия. С него се покрива обема по дисциплината „Земна механика“, изучавана в трети курс от петгодишния подготовка на магистри. Той може да се използва от инженерите в практиката като практическо помагало с отчитане на изискванията на нормативната база.
Настоящият учебник отразява изградената традиция на обучението на строителните инженери в България, като са внесени някои нови елементи, утвърдени в практиката през последните две-три десетилетия.
Авторите посвещават разработката си на всички дългогодишни преподаватели и наши учители от катедра Геотехника, дали своя принос в развитието и представянето на познанието в областта на Геотехниката на широката инженерна общност. Специални благодарности изказваме на рецензентите проф. Божидар Божинов и проф. Трифон Германов за предоставените материали от техните лекционни курсове и книги.

Papers by Miroslav Todorov

Proceedings of International Structural Engineering and Construction, 2016

Molecules

The temporal dynamics of anthropogenic impacts on the Pchelina Reservoir is assessed based on che... more The temporal dynamics of anthropogenic impacts on the Pchelina Reservoir is assessed based on chemical element analysis of three sediment cores at a depth of about 100–130 cm below the surface water. The 137Cs activity is measured to identify the layers corresponding to the 1986 Chernobyl accident. The obtained dating of sediment cores gives an average sedimentation rate of 0.44 cm/year in the Pchelina Reservoir. The elements’ depth profiles (Ti, Mn, Fe, Zn, Cr, Ni, Cu, Mo, Sn, Sb, Pb, Co, Cd, Ce, Tl, Bi, Gd, La, Th and Unat) outline the Struma River as the main anthropogenic source for Pchelina Reservoir sediments. The principal component analysis reveals two groups of chemical elements connected with the anthropogenic impacts. The first group of chemical elements (Mn, Fe, Cr, Ni, Cu, Mo, Sn, Sb and Co) has increasing time trends in the Struma sediment core and no trend or decreasing ones at the Pchelina sampling core. The behavior of these elements is determined by the change of t...

MODEL FOR THE INVESTIGATION OF THE BEHAVIOR OF PILES IN CYCLICAL EFFECTS, May 26, 2020

The deep foundation is characterized by the transfer of energy from the structure to the ground b... more The deep foundation is characterized by the transfer of energy from the structure to the ground base, leading to the development of long deformation effects. The concepts used in practice by superpositioning transfer as a function of both the friction on the skin surface and the back resistance demonstrates a deficiency resulting from the development of long-term deformations. Cyclic loading conditions are observed, as a consequence of the development of the peptization of the dispersion system and its auxetic behavior, the formation of strain processes, which leads to the redistribution of forces in the direction-reduction of the component of the skin friction at the expense of the peak-production of the pile bottom. Over the past few decades, a series of field test procedures in full-scale piles have been assembled in a natural environment of continuous update of the standardization base. Standard procedures are developed in a range of studies depending on the main working pile mechanism and consider four basic approaches for the testing of compressive load-fast, static with one or more loading cycles, bidirectional and dynamic tests. Numerical methods require consideration of model parameters in the context of the soil-pile interaction mechanism, examination of soil parameters and laboratory and in-situ methods of determination in the context of the strain level. Current studies have been proposed for small scale pile models serving as a verification procedure for the implementation of predictive analytical techniques.

Teaching Documents by Miroslav Todorov

Записки от лекции по Фундиране, 2022

Фигура 5.2. Схема на изчислителен модел, разпределение на напреженията и моментова диаграма в лин... more Фигура 5.2. Схема на изчислителен модел, разпределение на напреженията и моментова диаграма в линеен контактен (Winkler) модел със стойности на константите на пружинните опори K = 13440 kN/m .