scholarly journals Numerical Analysis of Soil Improvement for a Foundation of a Factory Using Stone Columns Made of Different Types of Coarse-grained Materials

2019 ◽  
Author(s):  
Jakub Stacho ◽  
Monika Sulovska
Keyword(s):  
Numerical Analysis ◽  
Accurate Determination ◽  
Soil Improvement ◽  
Coarse Grained ◽  
Stone Columns ◽  
Modified Method ◽  
Geological Conditions ◽  
Deformation Properties ◽  
Final Settlement ◽  
The Impact

Stone columns made of coarse-grained materials and crushed stone are one of the most-used technologies for soil improvement all over the world. Stone columns improve the strength and deformation properties of subsoil and reduce the time required for the consolidation of fine-grained soils. The impact of the improvement depends on the properties of the original subsoil as well as the properties of the coarse-grained materials used for the stone columns. The article deals with the effects of the properties of coarse-grained materials for stone columns on the settlement and consolidation times of improved subsoil for the foundation of a factory. Numerical modeling as a 2D task was performed using Plaxis geotechnical software. The numerical analysis included two methods of modeling stone columns in a plane strain model, i.e., one method often used by practical engineers in the region of Slovakia, and one modified method, which allowed for a more accurate determination of the final settlement and consolidation time. The method modeled stone columns as continuous walls, and the compaction of the soil between the stone columns was taken into account. The results showed that the type of coarse-grained material can significantly affect the final settlement and time of consolidation. Stone columns made of quarry stone were suitable in the given geological conditions regardless of the design of the mesh, while stone columns made of pebble gravel were suitable only with a mesh of 1.5 x 1.5 m.

scholarly journals Effect of Spacing between Stone Columns on the Behavior of Soft Soil

2021 ◽  
Vol 318 ◽  
pp. 01006
Author(s):  
Zeena A. Al-Kazzaz ◽  
Moataz A. Al-Obaydi
Keyword(s):  
Bearing Capacity ◽  
Soft Soil ◽  
Soil Improvement ◽  
Stone Columns ◽  
The Finite Element Method ◽  
Slight Improvement ◽  
Short Columns ◽  
Sectional Shape ◽  
The Impact ◽  
Spacing Length

Soil improvement by stone columns is extensively used, especially for the soft ones. This is because of their efficiency and no environmental impact. Several factors affect its efficiency in improving the mechanical properties of the soil, and the most important of these factors are the spacing, length, and diameter of the stone columns. In this study, the finite element method was used to study the impact of the spacing between the stone columns on the amount of settlement and the bearing capacity of the soil. The study comprises three different spaces (s) that were taken in relation to the columns’ diameter (d), which are (s/d= 3, 4, and 5). In addition, three types of the sectional shape of column involved circular, rectangular, and square sections with different lengths of (L/d=2, 4, 6, 8, and 10). The results showed that the spacing between the stone columns is effective when the vertical load is greater than 30 kN/m2, and below this, there is no effect of the spacing. In general, the settlement decreases, and the bearing capacity increases with the decrease in the spacing between the stone columns. The spacing becomes a more pronounced effect with the longer length of the stone columns. All sections of the stone columns with a short length of (L/d=2) showed the same settlement of 271 mm at a distance (s/d=5), which decreases by 7.4, 6.6, and 8.9% at a distance (s/d=3) for the circular, rectangular and square sections respectively. In the case of long columns (L/d=10), the settlement at (s/d=3) improves by about 27.5% which drop to about 18% at (s/d=5). A slight improvement in the soil's bearing capacity is associated with decreases in the spacing between the stone columns. The improvements in the bearing of soil treated with short columns (L/d=2) are 6.0, 6.5, and 4.7% for circular, rectangular, and square sections, respectively, when changing the distance from (s/d=5) to (s/d=3). Whereas they become greater when increasing the columns’ length to (L/d=10) to be 7.9, 9.2, and 6.4%.

scholarly journals DESIGN OF SUBSOIL IMPROVEMENT BELOW HALL FLOORS

2017 ◽  
Vol 10 ◽  
pp. 56
Author(s):  
Peter Turček ◽  
Monika Súlovská
Keyword(s):  
Bearing Capacity ◽  
Soft Clay ◽  
Thick Layer ◽  
Soil Improvement ◽  
Stone Columns ◽  
Clay Soils ◽  
Industrial Park ◽  
Construction Site ◽  
Geological Conditions ◽  
The Town

The construction of an industrial park is now being prepared near the town of Nitra. The investor fixed very strict conditions for the bearing capacity and, above all, the settlement of halls and their floors. The geological conditions at the construction site are difficult: there are soft clay soils with high compressibility and low bearing capacity. A detailed analysis of soil improvement was made. Stone columns were prepared to be fitted into an approximately 5 m thick layer of soft clay. The paper shows the main steps used in the design of the stone columns.

scholarly journals Numerical Modelling of the Subsoil Zone between Stone Columns

2019 ◽  
Vol 27 (4) ◽  
pp. 32-39
Author(s):  
Jakub Stacho ◽  
Monika Sulovska
Keyword(s):  
Radial Displacement ◽  
Numerical Models ◽  
Stone Columns ◽  
Deformation Properties ◽  
Practical Design ◽  
Replacement Technique ◽  
Strength And Deformation ◽  
The Difference ◽  
Final Settlement

Abstract Designing the improvement of soil using stone columns is usually based on simplified analytical or numerical models. Stone columns installed using a vibro-replacement technique can cause radial displacement of the original soil. It can cause radial compaction of the soil and increase the values of the strength and deformation properties, which are usually ignored in a practical design. The paper presents the results of a numerical analysis of a road embankment based on subsoil improved using stone columns. The changes in the properties of the original subsoil compacted by stone columns were analysed and taken into consideration in the models. The results showed that a model with homogenization of the subsoil and a model with stone columns transferred to continuous walls show similar results of the final settlement as well as the consolidation times. The differences between the values computed and measured were about 28 - 36 %. Taking into account the compacting effect of the original subsoil, the model with stone columns transferred to continuous walls allowed for the determination of more precise results when the difference between the values computed and measured was about 10 %.

Evaluation of Hydraulic Fracturing Models and Their Limitations to Predict No-Drill Zones for Horizontal Directional Drilling

2018 ◽  
Author(s):  
Saeed Delara ◽  
Kendra MacKay
Keyword(s):  
Hydraulic Fracturing ◽  
Safety Factor ◽  
Standard Procedure ◽  
Accurate Determination ◽  
Strength Properties ◽  
Analytical Models ◽  
Alternative Methods ◽  
Directional Drilling ◽  
Horizontal Directional Drilling ◽  
The Impact

Horizontal directional drilling (HDD) has become the preferred method for trenchless pipeline installations. Drilling pressures must be limited and a “no-drill zone” determined to avoid exceeding the strength of surrounding soil and rock. The currently accepted industry method of calculating hydraulic fracturing limiting pressure with application of an arbitrary safety factor contains several assumptions that are often not applicable to specific ground conditions. There is also no standard procedure for safety factor determination, resulting in detrimental impacts on drilling operations. This paper provides an analysis of the standard methods and proposes two alternative analytical models to more accurately determine the hydraulic fracture point and acceptable drilling pressure. These alternative methods provide greater understanding of the interaction between the drilling pressures and the surrounding ground strength properties. This allows for more accurate determination of horizontal directional drilling limitations. A comparison is presented to determine the differences in characteristics and assumptions for each model. The impact of specific soil properties and factors is investigated by means of a sensitivity analysis to determine the most critical soil information for each model.

scholarly journals Review of the relationship between aggregates geology and Los Angeles and micro-Deval tests

2021 ◽  
Vol 80 (3) ◽  
pp. 1963-1980
Author(s):  
Solomon Adomako ◽  
Christian John Engelsen ◽  
Rein Terje Thorstensen ◽  
Diego Maria Barbieri
Keyword(s):  
Los Angeles ◽  
Crystal Size ◽  
Grain Shape ◽  
Mechanical Performance ◽  
Pore Space ◽  
Construction Material ◽  
Engineering Properties ◽  
Coarse Grained ◽  
The Impact ◽  
The Relationship

AbstractRock aggregates constitute the enormous volume of inert construction material used around the globe. The petrologic description as igneous, sedimentary, and metamorphic types establishes the intrinsic formation pattern of the parent rock. The engineering properties of these rocks vary due to the differences in the transformation process (e.g. hydrothermal deposits) and weathering effect. The two most common mechanical tests used to investigate the performance of aggregates are the Los Angeles (LA) and micro-Deval (MD) tests. This study reviewed the geological parameters (including mineralogy, grain and crystal size, grain shape, and porosity) and the relationship to Los Angeles and micro-Deval tests. It was found that high content of primary minerals in rocks (e.g. quartz and feldspar) is a significant parameter for performance evaluation. Traces of secondary and accessory minerals also affect the performance of rocks, although in many cases it is based on the percentage. Furthermore, some studies showed that the effect of mineralogic composition on mechanical strength is not sufficient to draw final conclusions of mechanical performance; therefore, the impact of other textural characteristics should be considered. The disposition of grain size and crystal size (e.g. as result of lithification) showed that rocks composed of fine-grain textural composition of ≤ 1 mm enhanced fragmentation and wear resistance than medium and coarse grained (≥ 1 mm). The effect of grain shape was based on convex and concave shapes and flat and elongated apexes of tested samples. The equidimensional form descriptor of rocks somehow improved resistance to impact from LA than highly flat and elongated particles. Lastly, the distribution of pore space investigated by means of the saturation method mostly showed moderate (R = 0.50) to strong (R = 0.90) and positive correlations to LA and MD tests.

scholarly journals Monitoring the Impact of the Large Building Investments on the Neighborhood

2021 ◽  
Vol 11 (14) ◽  
pp. 6537
Author(s):  
Marian Łupieżowiec
Keyword(s):  
Groundwater Level ◽  
Soil Improvement ◽  
Deep Excavation ◽  
Large Area ◽  
Safety Measures ◽  
High Rise ◽  
The Impact ◽  
Large Building ◽  
Additional Safety ◽  
Made In

The article presents the concept of monitoring buildings and infrastructure elements located near large construction investments (the construction of high-rise buildings of the Oak Terraces housing estate in Katowice and the construction of a tunnel under the roundabout in Katowice along the intercity express road DTŚ). The impacts include deep excavation, lowering of the groundwater level over a large area, and dynamic influences related to the use of impact methods of soil improvement. The presented monitoring includes observation of the groundwater level with the use of piezometers, geodetic measurements of settlement and inclinations, as well as the measurement of vibration amplitudes generated during the works involving shocks and vibrations. It was also important to observe the development of cracks on the basis of a previously made inventory of damage. The results of the monitoring allow corrections to be made in the technology of works (e.g., reduction of vibration amplitudes, application of additional protections at excavations, etc.) or the use additional safety measures. Currently, there are also monitoring systems used during the operation of completed facilities.

scholarly journals Technical note: Boundary layer height determination from Lidar for improving air pollution episode modelling: development of new algorithm and evaluation

2017 ◽  
Author(s):  
Ting Yang ◽  
Zifa Wang ◽  
Wei Zhang ◽  
Alex Gbaguidi ◽  
Nubuo Sugimoto ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
High Performance ◽  
Accurate Determination ◽  
Technical Note ◽  
Strong Increase ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Retrieval Algorithms ◽  
The Impact

Abstract. Predicting air pollution events in low atmosphere over megacities requires thorough understanding of the tropospheric dynamic and chemical processes, involving notably, continuous and accurate determination of the boundary layer height (BLH). Through intensive observations experimented over Beijing (China), and an exhaustive evaluation existing algorithms applied to the BLH determination, persistent critical limitations are noticed, in particular over polluted episodes. Basically, under weak thermal convection with high aerosol loading, none of the retrieval algorithms is able to fully capture the diurnal cycle of the BLH due to pollutant insufficient vertical mixing in the boundary layer associated with the impact of gravity waves on the tropospheric structure. Subsequently, a new approach based on gravity wave theory (the cubic root gradient method: CRGM), is developed to overcome such weakness and accurately reproduce the fluctuations of the BLH under various atmospheric pollution conditions. Comprehensive evaluation of CRGM highlights its high performance in determining BLH from Lidar. In comparison with the existing retrieval algorithms, the CRGM potentially reduces related computational uncertainties and errors from BLH determination (strong increase of correlation coefficient from 0.44 to 0.91 and significant decrease of the root mean square error from 643 m to 142 m). Such newly developed technique is undoubtedly expected to contribute to improve the accuracy of air quality modelling and forecasting systems.

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