STABILIZATION OF SUBSIDENCE OF BUILDINGS OF MODERN MEDICAL CENTERS

the group of deformed structures includes buildings that have received unacceptable subsidence and deformation during the period of their construction and especially operation, which, however, do not interfere with the perfor-mance of their main functions, but may eventually collapse. Their causes are errors in engineering and geological surveys and design; violation of the rules for performing construction work and operation of buildings and struc-tures. Long-term geodetic observations of the precipitation of the foundations of buildings on pile foundations have shown that both absolute and relative stabilized values of subsidence in the vast majority of cases are less than them and the normative limit values are calculated. Therefore, the group of deformed buildings on pile foun-dations includes somewhat less often similar objects with shallow foundations. The reasons for excessive subsid-ence of the foundations of pile foundations of buildings (and as a result, the occurrence and development of cracks and other deformations in load – bearing structures), in addition to these, are most often: unjustified use of increasing correction coefficients for the results of compression tests of highly acidic soils; the lower ends of the piles falling into layers of weak soil; the tip of the piles sinking from the design mark; overestimation of the bear-ing capacity of the piles due to non-compliance with the optimal time of their "rest" after immersion or erroneous interpretation of the graphs "load-pile sediment"; excessively close placement of neighboring piles in the plan, which when they are immersed, especially in the sand, leads to "pushing" up previously submerged; uneven load-ing of piles as part of the grillage; deformation of existing buildings and structures when driving piles near and tongue-and-groove, the development of pits, etc.

COMPARATIVE ANALYSIS OF NATM CONSTRUCTION TECHNOLOGIES OF DNIPRO METRO ESCALATOR TUNNEL

Purpose. On the basis of the comparative analysis to carry out a substantiation of the most expedient and rational way of strengthening of a weak massif during a construction of Dnipro metro escalator tunnels by NATM. Methodology. To achieve this goal, an analysis of construction technologies in weak soils was conducted. The most used technologies are Forepoling Umbrella System (FUS), artificial ground freezing and chemical cementation. The peculiarities of carrying out each of the technologies for the conditions of inclined production were analyzed. It is determined how each of the technologies is applied to escalator tunnels and implements the strengthening of weak soil. Findings. The advantages and disadvantages of three technologies for fixing weak soil around the escalator tunnel are identified. Based on comparative analysis, it was found that the only technology that provides increased strength parameters of loamy soils, characteristic for the upper part of the escalator tunnel of the Dnipro metro, is the technology of chemical strengthening (cementation). In some cases, if necessary, short sections of sloping course, characterized by particularly weak soil, can be supported by several pipes, without creating a continuous leading mount. The results of the analysis are the basis for further substantiation of cementation, which creates a multilayer system "reinforced soil massif – temporary fastening – permanent lining". Originality. Based on the results of comparative analysis of three technologies for escalator tunnel construction by NATM, it is proved that the use of cementation not only increases the strength of the soil during drilling, but also further in operation serves as an additional element of the multilayer system "reinforced soil massif – temporary fastening – permanent lining". Practical value. In the course of research, the substantiation of cementation as the most rational and effective technology of strengthening of the surrounding weak massif at construction of the Dnipro metro was carried out.

Numerical Analysis of Soil Reinforcement using Geocell infilled with Quarry Dust Powder

Massive urbanisation and infrastructural development caused by the growing population have taken place during the last decades. This means that in a rapidly expanding world economy we are running out of land. This problem has led to the use of ground improvement techniques to enhance the usability of land masses that were once not considered suitable for the development of infrastructure. Geocell is an innovative soil stabilisation product for civil engineering and development of infrastructures. They are cell containment systems which have been produced as an easy and durable material to stabilise and protect the compaction of the soil. The environmental concern regarding the disposability of quarry dust powder (QDP), produced from production units of M-sand (Manufactured sand), is of concern to the environment. The statement that is “waste of one industry should become the raw material for another” and that drawback can be addressed effectively by using it to improve the geotechnical characteristics of the weak soil. The purpose of this study is to find the optimal geocell-layer geometry and optimum combination of QDP infills to produce less settlement at a particular load using PLAXIS 2D software. The characteristics that have been varied are quarry dust powder in infill, geocell material and frequency of loading. These parameters were used for simulations to study the response of load vs settlements and the FOS of the slope. The FOS on the slope on the terrain was found to be 4.5, a steady slope. An optimised reinforcing mattress was ultimately found out.

An experimental approach to microbial carbonate precipitation in improving the engineering properties of sandy soils

Purpose Stabilization of weak soil can be achieved through different methods, some of which include jet column, cement stabilization and fly ash stabilization. Unfortunately, the use of the aforementioned methods of soil improvement affects the environment negatively thereby leading to environmental degradation. With the aforesaid impediment in mind, the need for devising methods of weak soil improvement becomes pertinent. Methods Bacillus sp. — a non-pathogenic organism found abundantly in soil — was investigated in this study as a potential agent of soil improvement. The usability of Bacillus sp. in soil improvement was investigated with direct shear tests and permeability tests under optimum conditions in this study. Result Time-dependent study on the effect of the ureolytic bacteria Bacillus sp.-induced calcium carbonate precipitation shows reduction in permeability and increase in the strength of the soil under study. On exhaustion of the available nutrients in the soil, however, the strength of the soil is not negatively impacted. Conclusion Microbially induced calcium precipitation by Bacillus sp. is effective in soil improvement as such it may serve as substitute for conventional soil stabilization techniques. The ability of the bacteria to precipitate calcium carbonate in the soil leads to reduction in the permeability and increase in the shear strength of the soil.

Numerical Evaluation of Settlement of Strip Footing Resting on Cavity and Weak Soil Profile

This study numerically investigates the effects of different subsurface sources of weaknesses within a soil profile on the settlement of a strip footing using the finite element method (FEM). During the first phase of the study, the influences of size, shape, depth, and distance of cavity from the center of the footing are evaluated. It is noted that the settlement of foundation is increased when the cavity is located at smaller depths and closer to its center. It is concluded that there is a critical zone, where the risk level of settlement (especially differential settlement) due to the cavity is high. The depth of this critical zone is found to be 2.5B (where B is the width of the footing) below the simulated loading area. In the second phase of the study, increasing the degree of weakness of a certain low stiffness layer within the soil profile below the loaded area is simulated as another factor that increases the settlement risks. It is shown that the depth of this weak layer highly controls the settlement of footing even if it is situated at depths >2.5B.

Stabilization of Soil by the Composition of Eggshell Powder and Shredded PPE Kit

In the world full of crises, also the rising demand for PPE suits and masks would lead to another wave of biomedical waste disposition crises. The disposal of thrown away wastes causes a serious issue as the waste are most of the time are non- biodegradable and these are also not fit for incineration. Soil stabilization improves the engineering properties of the weak soil, by proper compaction and additional materials such as lime, concrete, but these materials are becoming expensive day by day, hence plastic by the composition of egg shell powder could enhance the properties and can be a sustainable replacement for lime, concrete, etc. as stabilizer. Through much experimental investigation it has been showed that plastic and egg shell powder can be used as an effective stabilizer with encountering waste disposal problem as well, along with the economical solution for stabilizing weak soil. This PPE stripes/shredding are known for its high strength, low cost, significantly less dangerous for the environment. The combined effect of PPE stripes/shredding along with egg shell powder can enhance engineering properties of soil.

Influence of positions of the geotextile on the load-settlement behaviour of circular footing resting on single stone column by 2D Plaxis software

Purpose: This study aims to study the load – settlement behaviour of circular footing rested on encased single stone column. Design/methodology/approach: The effect of vertical, horizontal and combined verticalhorizontal encasement of stone column on the load carrying capacity were examined numerically. The effect of stone column dimension (80 mm and 100 mm), length (400 mm and 500 mm), and spacing of reinforcement on the load carrying capacity and reinforcement ratio were assessed. Findings: The obtained results revealed that the load carrying capacity of geotextile encased stone columns are more than ordinary stone columns. For vertically encased stone columns as the diameter increases, the advantage of encasement decreases. Whereas, for horizontally encased stone column and combined vertical- horizontal encased stone column, the performance of encasement intensifies as the diameter of stone column increases. The improvement in the load carrying capacity of clay bed reinforced with combined verticalhorizontal encased stone columns are higher than vertical encased stone columns or horizontal encased stone column. The maximum performance of encasement was observed for VHESC1 of D = 80 mm. Research limitations/implications: For this study, the diameter of footing and stone column was kept same. The interface strength factor between stone column and clay bed was not considered. Practical implications: The encased stone column could be use improve the laod bearing capacity of weak soils. Originality/value: Many studies are available in literature regarding use of geosynthetic as vertical encasement and horizontal encasement of stone column. The study on combined effect of vertical and horizontal encasement of stone column on load carrying capacity of weak soil is very minimal. Keeping this in view, the present work was carried out.

COMPARATIVE ANALYSIS OF TECHNOLOGIES OF MICROPILES ARRANGEMENT DURING STRENGTHENING OF WEAK SOIL BASES

Purpose. Perform a comparative analysis of drill and injection (jet-grouting) and drill and mixing technologies of micropiles arrangement of weak soil bases with the identification of technological features that significantly effect on the design and calculation of weak soil bases strengthening. Methodology. To solve this problem, was conducted of the detailed analysis of the most effective methods of micropiles arrangement during the strengthening of weak soil bases (physical immersion, bored and packing of concrete, drill and injection of ground, drill and mixing soils and application of special effects). Peculiarities of technological parameters of jet-grouting and drill and mixing technologies are considered in detail. The advantages and disadvantages of each of the technologies are revealed. It is proved that the drill and mixing technology has a greater degree of prediction of the stress-strain state change of the inhomogeneous base. To determine the influence of deformation characteristics, a spatial finite-element model based on a flat prototype was created, which was built using automatic triangulation of the professional calculation complex SCAD. Findings. A significant reduction of the deformed state at an almost constant stress state is obtained. When the deformation characteristic increases by 3 times (the ratio of the modulus of elasticity of the soil cement pile and the weak soil), the vertical displacements of the foundation decrease by 1.23 times. Originality. It consists in obtaining the dependence of the change of vertical displacements and stresses on the modulus of elasticity of the soil cement micropile, created on the basis of drill and mixing technology. Practical value. It consists in the obtained results of comparative analysis of substantiation of micropile installation drill and mixing technology during strengthening of weak soil bases with definition of technological features and choice of drill and mixing as the most effective variant from the point of view of technology realization.

Engineering Properties of Sandy soil Improvement with Bacillus Simplex

Purpose: Stabilization of weak soil can be achieved through different methods, some of which include: jet column, cement stabilization and fly ash stabilization. Unfortunately, the use of the aforementioned methods of soil improvement affects the environment negatively thereby leading to environmental degradation. With the aforesaid impediment in mind, the need for devising methods of weak soil improvement becomes pertinent. Methods: Bacillus sp. - a non-pathogenic organism found abundantly in soil - was investigated in this study as a potential agent of soil improvement. The usability of Bacillus sp. in soil improvement was investigated with direct shear tests and permeability tests under optimum conditions in this study.Result: Time-dependent study on the effect of the ureolytic bacteria Bacillus simplex induced calcium carbonate precipitation shows reduction in permeability and increase in the strength of the soil under study. On exhaustion of the available nutrients in the soil however, the strength of the soil is not negatively impacted.Conclusion: Microbially induced calcium precipitation by Bacillus sp. is effective in soil improvement as such it may serve as substitute for conventional soil stabilisation techniques. The ability of the bacteria to precipitate calcium carbonate in the soil leads to reduction in the permeability and increase in the shear strength of the soil.