Construction and Geotechnics

The article aims at analyzing the results of the first stage of the master’s program development called “Innovative technologies of low-rise construction”. In Russian it is considered to be a market trend to focus on the low-rise housing, as it has a number of advantages compared to the multistorey housing. Low-rise housing makes it possible to reduce costs, time, use energy-efficient technologies and act autonomously. A lack of highly qualified personnel is a constraint against a widespread application of innovative technologies in our country. The article pays much attention to the disciplines creating unique master’s professional competencies. During the master's program students gain skills related to technical risk and geotechnical assessment when it comes to low-rise housing construction. They learn how to design energy-efficient foundations and energy-efficient constructions; use advanced building materials and innovative construction techniques. The article could be of interest to a wide range of geotechnical engineers and builders who want to extend their areas of expertise and acquire new professional knowledge and skills. It is also interesting for graduates looking for a vocational retraining or those who plan to use the knowledge and skills for themselves. The “Innovative technologies of low-rise building” master’s program was developed based on the standards used for the “Construction” major and requirements of potential employers to the program graduates. The article presents the clearly defined goals and objectives of the developed program that are consistent with the mission of Perm National Research Polytechnic University and with the demands of the potential target customers.

The paper describes an integrated computer-based technology optimizing site survey operations (e.g. number of test holes) and office work (geological activities). This objective is achieved by analyzing structure settlements and tilts online at each current stage of the survey operations. To this end, the test data (e.g. qc and fsprofiles) is uploaded online after each survey stage into a computer that processes the data and calculates the potential structures’ settlement and respective tilts at this stage. Then the obtained data is downloaded back to the server, and the geological survey team decides to go on or to stop the survey, depending on the difference between the data of the current and the previous stage. The subsoil ratio distribution under future structure is calculated at each stage and sent to a Design Engineer at the last stage for future design work. The method does not require any office work or geological data processing, because no geological report is required, and all the above operations are carried out on site along with the survey. The Designer receives three values, such as one settlement and two tilts. Such sequence of operations is possible thanks to a new method for subgrade ratio distribution analysis and application which has been developed in GEOTEK. The respective software and hardware were patented. Static, dynamic penetration and drilling sounding techniques are proposed to test soil properties in situ. Soil data is processed with the help of known correlation equations to obtain physical and mechanical soil parameters. The number of test holes is determined by the designed subsoil-structure sensitivity to the test data already available by online settlement and tilts analysis during the tests in situ. The associated hardware and software for soil testing in situ and data processing are described. Test data collection and processing is performed with ASIS software together with an additional software code for the test data interpretation. The data is uploaded online to the computer on site or elsewhere to calculate subsoil parameters, followed by structure settlements and tilts analysis online. If necessary, the test data can be uploaded to a remote server of the surveyor. The settlements at the test points that are caused by the mean structure pressure on the subsoil are computed for pressure. Firstly, they are computed at the test points, and then the subgrade ratios are computed at these points which are interpolated to the whole foundation surface according to Shepard’s formulae, while the computation variants are considered for different values in Shepard’s approximation formulae.

The article is devoted to the problem related to determining the technological settlements of foundations in nearby buildings during the construction of a diaphragm wall. It is based on the materials of the scientific research work which has been carried out in 2015 as the governmental assignment (customer FAU "FTSS"). It includes the available data analysis gained from monitoring the technological settlements, the analysis of existing methods aimed at estimating technological settlements and results of numerical modeling of the diaphragm wall construction. As a result, a large number of both foreign and national sources have been analyzed which revealed the following facts. Firstly, technological settlements vary in a wide range from 1 to 63 mm. Secondly, the quantitative evaluation of the technological settlements during the construction of the diaphragm wall is performed by using the finite element method; and the ratio between the settlements gained from the monitoring data and the settlements gained from estimations varies from 48 to 175%. The main modeling stages in constructing the diaphragm wall are the trench excavation and concreting. Two main approaches to modeling the trench excavation stage have been identified, i.e. modeling of the excavation by changing the soil properties within the trench or by the load equivalent to the hydrostatic pressure of the bentonite slurry. As a rule, when modeling the concreting stage, a bilinear dependence proposed by Lings is used. A model dimensionality is an important issue for the numerical calculation of technological settlements. In most studied works, a three-dimensional model was used in the calculations, which allowed considering the size of the panel length. Calculations related to the 2-dimensional model lead to overestimated values of soil displacements. To verify the method determining the technological settlements, the numerical modeling in PLAXIS 3D was carried out using the data from the construction site of a multi-storey building in Greater Cairo. As a result of this simulation, a good compliance of the calculated technological settlement with the monitoring data was obtained (the settlement according to the monitoring data is 7 mm, the settlement according to the calculations is 6 mm). Based on the example of the construction site in Greater Cairo, it was assessed how various factors (the distance between the diaphragm wall trench and the foundation of the building, the panel length, the load under the foot of the foundation and the density of the bentonite slurry) influence technological settlements. This assessment has shown that it is important to take the investigated factors into account when estimating the technological settlements.

This article considers the issues of producing buildings and constructions on potentially dangerous landslide slopes. It shows the advantages of the foundation setting in such conditions using piles which are set into the ground by a static load. The technologies which are used to insert piles during new construction operations and during the reconstruction of buildings are also described in this article. A new efficient technology is proposed for production of combined piled foundations which allows reducing construction time and costs. The idea of the technology is that due to a certain sequence of operations related to the construction of foundations and upper structures of the building, the load from an incompletely constructed building is firstly perceived by the slab foundation, and then, as the building is constructed, the increasing load is transferred to the piles set through the holes in the plate. On the one hand, this makes it possible to fully utilize the bearing capacity of both the foundation slab and the pile of the combined foundation, and, on the other hand, to reduce the number of piles and, to some extent, control the structure settlement when it is being constructed. In addition, the description and the results of laboratory and field experiments are given using the testing model of studying the piled foundations which has been developed according to the proposed technology. This technology can be used both to build structures on potentially dangerous landslide slopes, as well as in ordinary conditions of mass industrial and civil constructions. Nowadays all the main elements of the proposed technology have been worked out. In particular, a method determining the bearing capacity of piles when they are inserted using the creeping relaxation regime, the technology of piling into leading wells, and the technology of increasing the bearing capacity of immersed piles.

In case of an intensifying production of high-rise buildings, geotechnical engineers often face design problems related to high loaded soil bases with a load up to 1 MPa. This is the reason of a widespread use of deep foundations made of various shape piles including barrettes. Barrettes have become commonly used in many countries, as they are able to bear large vertical and horizontal loads. However, unlike the traditional piles, the studies of barrettes operational characteristics are far behind practice. This is mainly due to a high cost and complexity of full-scale experiments regarding this type of foundation. Therefore, in present investigations the researchers focus on studying the bearing capacity, settlement and mobilization of the shear forces on side surfaces that are obtained via sensors installed on the experimental barrettes. However, there are interesting and understudied questions about the interaction of barrettes with the soil at a distance from the side surfaces (the interaction problem), choosing an optimal shape (aspect ratio), placement pitch in two directions, and stress concentration in the corner areas. These problems can and must be solved by numerical methods to obtain high-quality results that can subsequently lead to real cost-cutting results. Finite element computer applications like PLAXIS 3D allow to successfully solve the aforementioned problems and make algorithms in order to produce optimal design solutions. The article presents the course and results of numerous finite element calculations to study the interaction of a single and group barrette with its soil base. It became possible to determine the interaction zones of a single barrette along short and long sides, which allowed gaining a more efficient location of them in terms of the composition of the foundation. The results are shown by solving the test problems similar to real projects.

This article considers stamping tests of full-scale models of reinforced foundation pads in real engineering and geological conditions of the city of Perm. These tests entail the final experimental stage in studying the bearing capacity of reinforced foundation pads. Numerical modeling was performed at the first experimental stage, the results of which were used to formulate the basic operation parameters of the reinforced foundation pads. Before the full-scale tests, model stamping tests of various types of reinforced foundation pads had been made and formulated on the basis of the numerical modeling results. The results of the model stamping tests made it possible to clarify the qualitative parameters of the work, to reveal the rational design of the reinforced foundation pads. In order to check the results of numerical modeling and model stamping tests, as well as to find the real bearing capacity of the reinforced foundation pads, full-scale stamping tests of specially prepared reinforced foundation pads were carried out. The main purpose of the experimental work is to obtain real parameters for the operation of reinforced foundation pads. To achieve this goal, certain objectives were identified, such as: - identify the regularity of settlement for the reinforced foundation pads under load by constructing the experimental plots of the "settlement-pressure" dependence; - estimate the bearing capacity at a maximum settlement of 12 cm; - study the stress-strain state of the base of the improved reinforced foundation pad under load by measuring stresses and deformations using soil pressure cells and marks. The solution of these problems will development a technique of calculating the bearing capacity of reinforced foundation pads.

The main controlled parameter in the production of bases is the compaction ratio; however, deformation characteristics are important for the prognosis of bases settlement. The aim of the research is to determine the relation between the monitored parameters at the construction site and the characteristics used in the design of the foundations, which will allow a quick and effective control of the quality, as well as a prediction of the settlement of fill soils. There are various methods aimed at an express control of the density of fill soils. One of them is the impact stamping method with the help of a dynamic densitometer. The problem of investigating the applicability of this method in industrial and civil construction is relevant. This paper presents the results of experimental studies aimed at assessing the applicability of the DPG-1.2 to control the deformation characteristics of fill soils. The research was carried out in the laboratory conditions of Construction Production and Geotechnics Department of Perm National Research Polytechnic University. The compaction ratio and soil moisture were accepted as the controlled parameters. As the measured parameters, we accepted the compression modulus of deformation, the dynamic modulus of elasticity, force and settlement. The subject of investigation is uniform coarse sand with a maximum density of 1.74 kg/m3 and an optimum moisture content of 14 %. 18 series of tests were carried out with different coefficients of compaction at a constant humidity. Based on the results of the experimental studies, the dependencies were obtained, i.e. the dependence of the compression modulus of deformation, the dynamic modulus of elasticity, and the plastic precipitation on the coefficient of compaction; dependence of the impact force on the plastic settlement. Also, additional experiments were carried out to determine the depth of the compressible strata from the impact load. The obtained dependences were analyzed from the point of the effect of the compaction ratio on the deformation characteristics, as well as the determination of the applicability limits of the dynamic densitometer during the layerwise control of the fill soil compaction.