Construction and Geotechnics

The foundations that serve together with the soils of the foundations of buildings and structures are directly or indirectly borrowed by Man from what was created in Nature - supports of her living and non-living creations: the feet of Man or animals, the roots of plants. Different types of foundations have their counterparts in nature. It is interesting to see how and why these or other forms of Supports appeared, their sizes, how they change, adapt to changes in the environment during the existence of the creation of Nature. And how a Man can use the finds of Nature in his activities in the design of foundations and even buildings and structures. Examples are a pillar foundation that can be cut from a person’s foot; slab foundation - paws of waterfowl; Pile foundation essentially has much in common with the legs of hoofed animals. The heat-insulated foundation can be compared with the paws of a polar bear, whose feet are “lined” with fur. Particular attention is paid to the root system of the tree, which can be considered an ideal foundation. The ability of various trees to adapt to the terrain on which it grows is an example of a possible approach to designing rational types of foundations. The principle of inclusion in the work under the loads of the soil surrounding the root system is implemented in the Tree. At the same time, the roots “reinforce” the surrounding soil, create from it a single system, which perceives the loads acting on the tree. Such an approach is implemented, for example, when constructing foundations or hardening soils using the geotechnogenic system.

The paper presents the results of a study to determine the stress state on the contours of underground workings, the cross section of which has the form of a trapezium, a triangle, a rectangle, a rhombus, astroids and an ellipse. The strength of underground workings of trapezoidal and elliptical cross-sectional shapes was studied for given values of uniform pressure applied at the points of the outlines of the workings. The analysis of the stress state at the points of the contours of underground mine workings has been carried out. As a mapping function, a complex variable function is used, which is a third degree polynomial. The stress state at the boundary of the underground horizontal excavation, which has a predetermined shape, is investigated depending on the value of the numerical pressure value acting along this boundary with a predetermined value of the lateral distribution coefficient. Graphic representations of stress diagrams acting on the contours of the workings are given.

Together with our partner Baudynamik Heiland & Mistler the university of Applied Sciences is developing a practical prediction method for construction machine induced vibrations. The project is sponsored by BMWi. The new method takes the construction machine parameters and the soil characteristics much more realistically into account. This is done by a special measuring procedure. The first step of this procedure is to measure the transfer admittance of the specific machine at a location „1“ and the vibration responses at different distances. Then the machine spectra are calculated from the measured data at each distance. In a second step the transfer admittance i.e. in building (location „2“) are measured for an impulse force induced by a special impulse generator. Then the previously obtained machine spectra together with the impulse response is mathematically transformed in the frequency domain to obtain a prediction of the vibrations in the building caused by the machine by back transformation in the time domain. The so predicted vibrations can be used to evaluate the admissible vibration given DIN 4150-3. The two step procedure is based on the assumption that the vibrations transfer in the soil and in the building can be described as linear systems. Within the paper this assumption will be proofed for a specific vibration plate. The procedure describe above is applied to three different places with completely different soil characteristics. The machine force spectra are obtained for each soil at different distances. The data evaluation shows the significant influence of the distance to the calculated machine spectra. The influence of the impulse level (lower or higher impulse forces) shows to be of minor significance. A comparison of the force spectra obtain for the three different soils shows that the machine spectra are in satisfactory accordance. As result it can be stated that the assumed of linear vibration transfer for vibrations caused by the vibration plate can be satisfactorily proofed. The proposed prediction method is further developed and proofed.

The authors of the article revealed the directions of development of water supply and sanitation systems of multifunctional buildings, the specific features and the most rational design solutions of systems. Design of water supply and sanitation components of the complex (residential part, infrastructure) is based on standards and experience in the design of such facilities located separately and operating independently. At the same time, the design has specific features because many objects are parts of a single complex. For example, such as the duplication or redundancy of individual elements of the system; the device of a separate fire extinguishing system, including a reservoir with a supply of water; the use of additional equipment aimed at saving water; installation of local wastewater treatment facilities of industrial premises; design of rain sewers with closed outlets. The article presents a simplified method for determining the maximum hourly and second water and wastewater flow rates for buildings with a large number of water users.Determination on set of rules30.13330.2016 is conducted only for the most water-intensive consumers, which account for more than 90 % of the daily water consumption of the entire complex and the number of which usually does not exceed three.The expenses of other small water consumers are taken into account additionally as a percentage of consumption of water-intensive facilities. It is determined that the share of small consumers in the maximum hourly consumption of water and wastewater is 6 %, in the maximum second consumption - 4,5 %. The collected information is used in the design of a specific object - a complex of two residential buildings on a common stylobate part, which houses the infrastructure facilities of administrative, commercial and fitness purposes.

Research studies of polymer concretes are frequently carried out under the action of static loads while the material is affected by cyclic loads, most often, low-cycle as a result of its work in the structure. In the case when the level of stresses caused by these loads exceeds a certain limit, irreversible damage accumulation processes begin to occur in the material, which lead to the formation of cracks. In the future, the stress concentration at the edge of the crack contributes to its development. Most often cracks occur at the surface of the part, but sometimes in the thickness of the material. This process weakens the section and after some time, when the crack reaches a critical length, the part or structure is destroyed. As a rule, they are destroyed without visible residual deformations, even in cases when they are made of plastic materials. It was suggested that under the influence of variable stresses material gradually degenerates over time, as if "gets tired" (fatigued). Material fatigue is a process of gradual accumulation of damage under the influence of variable stresses, leading to the formation of cracks and destruction of the material. The peculiarities influencing low-cycle stresses on strength characteristics of polymer concretes based on furfural acetone monomer (FAM) are considered in the article. The regression equation has been obtained as a result of experimenting on a polymeric composite material which allowed constructing the response surface of the low-cycle fatigue of the polymeric composite material based on the resin of furfural acetone monomer. A second-order plan for three factors studying low-cycle fatigue of a tested composite material is also presented in the paper. It has been established that the ratio of the polymer component to the filler and the coarse aggregate spreading factor are the fundamental ideas influencing the cyclic durability of polymer concretes while the thickness of the polymer bonding layer is an insignificant factor.

Today, more than half of the world's population lives in cities. Expanding, absorbing woods, meadows, ponds and swamps, covering the earth with pavement, rushing up to the sky and the depths of the city are changing the face of our planet. Given the ability of green spaces to have a positive impact on the environment, they should be as close as possible to the place of life, work, study and rest of people. It is very important that the city was a biocenosis is not absolutely favorable, but at least not harmful to human health. One of the solutions to the city's problems is the organization of parks. Green spaces not only create favorable microclimatic and sanitary conditions, but also increase the artistic expressiveness of architectural ensembles. Parks solve a number of environmental problems in the city. First, reduce air pollution. Best absorb the sounds of trees and shrubs with thick crowns, dense large leaves, with a large number of small branches (maple Holly, Linden, oak petiolate, poplar canadian). The penetration of noise in the Park prevent dirt open space - grass. Reducing noise, the Park meets the task of reducing dust and air pollution. Polluted air in the city, poisoning the blood with carbon monoxide, causes a non-smoker the same harm as Smoking a pack of cigarettes a day. And the organization of the Park with multi-row strips of trees and shrubs with a width of 50 m and a height of 15-20 m reduces the level of air pollution by 70-75 %. Coming to the Park, a person does not leave the boundaries of the city and at the same time experiences psychoemotional relief, removal of irritability. Caring for green spaces, protecting and multiplying them, every resident of the city can make a contribution to improving the ecology of the city. But, despite the development and the desire to make the city more green, in this area there are many problems related to the proper placement, maintenance and use of parks.