Load-settlement Characteristics Research Articles

Evaluation of Interface Behaviour and Load-Settlement Characteristics of Geosynthetics-Reinforced Landfill Mined Soil like Fraction for Fill Applications

Evaluation of Interface Behaviour and Load-Settlement Characteristics of Geosynthetics-Reinforced Landfill Mined Soil like Fraction for Fill Applications

Behaviour of geocomposite and geotextile reinforced soil bed- an experimental study

Soil reinforcements using geosynthetics have been utilized in many areas of geotechnical engineering. In this study, a series of model tests have been conducted to understand the influence of two different kinds of planner geosynthetics in a denser soil medium, and the effect of different parameters premediated the load-settlement characteristics have been evaluated under monotonic loading. The parameters premeditated in this investigation include the effects of the top layer location, size, and the number of reinforcing layers, which were articulated in a non-dimensional ratio as bearing capacity ratio (BCR). The test findings showed the possible benefit of using reinforcements on a sandy soil bed influenced by the configuration of the mattresses. An increasing trend of improvement has been observed irrespective of the type of planner geosynthetics with optimum reinforcement arrangements (u = 0.33B and b = 4). However, higher improvement was exhibited using geocomposite (GC) compared to geotextile (GT). Using optimum reinforcement arrangements, geocomposite shows more than a threefold increase in BCR, i.e., a 19.59 % incremental increase compared to geotextile. It is evident from the results that designed reinforcement arrangements have a high potential to improve soil-bearing capacity.

Experimental and numerical evaluations of load settlement response of helical piles in soft clay

Use of helical piles has become increasingly popular since last few decades for numerous advantages and installation convenience. They may consist of isolated helical plate welded to a central shaft or continuous screw type piles. The load transfer mechanism of helical piles is complex compared to the conventional vertical driven piles. Although limited contributions are available on the performance of helical piles including theoretical and experimental studies, still there are major scopes for further research. The authors have conducted a series of laboratory experimentations on axial load-settlement characteristics of model helical piles made of high tension steel in soft clayey soil, followed by 3D finite element analysis using ABAQUS. The numerical results were found to be close to the experimental observations. Using the numerical model, extensive parametric studies were conducted. The load-settlement response was found to be mostly logarithmic. The pile capacity was found to be influenced significantly by the pitch and embedded pile length. The FEM analysis revealed maximum plastic strain and displacement to develop adjacent to the pile-tip and the interface, while negligible at the boundaries. The interface shear stress distributions are also studied. From the entire investigation, a set of important conclusions are drawn.

Use of recycled waste plastic bottles in a ground engineering technology

Previous studies have investigated internal reinforcing of granular columns to further improve the loading, settlement and deformation characteristics of these columns which are popular for improving load carrying capacity, reducing settlement, mitigating liquefaction and improving drainage. This research expanded on past studies where reinforcement materials, generated from the recycling process of waste polyethylene terephthalate (PET) bottles, were used to improve the engineering characteristics of granular columns so as to potentially generate more sustainable construction technologies which is in line with the Sustainable Development Goals of the United Nations. A series of laboratory tests were undertaken on single columns which were installed in a steel cylindrical tank and subjected to a vertical compression load; the reinforced granular columns were improved with PET bottles in the form of flakes. The load-settlement characteristics were electronically recorded and a physical model of the deformation of each column was built using a paste of plaster of Paris. Modelling of the deformed columns was necessary to establish the maximum bulging diameter and the position at which it occurred along the length of the column. The results obtained showed that the highest improvement in vertical applied load was 143% and it was recorded for a test which was conducted on a column installed in the wetter silt bed, with a flakes concentration of 5.6%. In terms of settlement, a drastic reduction in settlement was observed with the inclusion of the flakes in the columns for tests on the wetter silt. The lowest settlement of 13 mm was obtained in the test with the wetter silt bed and flakes content of 5.6%. Additionally, inclusion of the flakes also reduced the extent of lateral bulging, depending on the testing conditions.

Geocell Mattress Reinforcement for Bottom Ash: A Comprehensive Study of Load-Settlement Characteristics

Geocell Mattress Reinforcement for Bottom Ash: A Comprehensive Study of Load-Settlement Characteristics

Assessment and analysis of load-settlement characteristics for square model footings on sand beds enhanced with vertical pultruded fibreglass reinforced helical piles

ABSTRACT This article introduces an innovative ground enhancement technique using vertically oriented fiberglass pultruded pipes with helical bottoms. The study focused on prefabricated helical piles of varying lengths and cross-sectional areas as reinforcement in sandy soil. Experimental investigations were conducted on a laboratory model square footing on sand with Pultruded Fiber Reinforced Helical (PFRH) piles installed beneath. A parametric study analyzed the effects of PFRH pile slenderness ratio, sand bed conditions, and helical plate diameters using model plate load tests. Results showed significant improvements in settlement characteristics and load-carrying capacity with PFRH piles. Load capacity increased with the slenderness ratio up to 20, beyond which improvements were minimal. Denser sand enhanced bearing capacity without reinforcement, while PFRH piles performed best in medium-density sand. Larger helical plates also increased load capacity. Multivariate linear regression confirmed the reliability of the findings, highlighting the potential of prefabricated helical piles for soil reinforcement.

Load-Settlement Characteristics of Stone Column Reinforced Soft Marine Clay Deposit: Combined Field and Numerical Studies

Foundations supporting infrastructure built on soft and compressible marine soil are unlikely to sustain due to possibility of undrained shear failure or excessive settlement of the supporting soil. This necessitates the importance of implementing an adequate ground improvement strategy. Among different techniques, soft soil reinforcing by the installation of stone columns is one of the most successful methods in terms of long-term stability of foundations. To investigate the load-settlement characteristics of such reinforced soil, a group of closely spaced stone columns was constructed at a location along the eastern coast of Australia. The site geology revealed thick layers of soft, compressible marine clay deposit. These stone columns were loaded by constructing earthen embankment and the resulting load-settlement characteristics were measured by an array of sensors. A two-dimensional plane strain analysis was performed using finite element modeling simulations. Comparison of numerical results with the field data demonstrated accuracy of the numerical model. Additional studies were carried out to investigate the efficiency of the model. This paper integrates the new findings from the full-scale field study and advanced numerical simulations while drawing pertinent conclusions.

Experimental investigation on reinforcement effect of sustainable materials for different subgrades

Through the physical model tests of subgrades under different working conditions, the feasibility of using waste tires and construction wastes as reinforced subgrades is investigated. The effects of compaction degree, subgrade material and reinforcement type on subgrade performance are studied. The test results show that the increase of compaction degree brings about an increase of the bearing capacity and initial stiffness of subgrades, inducing a settlement reduction. The load-settlement characteristics of construction waste subgrade are better than that of sandy subgrade, especially at a lower settlement. In general, with the development of footing settlement, the bearing capacity of reinforced sandy subgrade gradually exceeds the unreinforced one. With regard to the construction waste subgrade, the reinforced effect of both geocell and waste tire is better under high pressure, and the reinforced effect of waste tires is better than that of geocell under the same condition. Furthermore, construction waste can effectively reduce the uplift of the subgrade surface compared with the sandy soil, and the waste tires can help to redistribute the soil pressure into a wider space.

Displacement piles - classification and new methods for the calculation of bearing capacity

The paper presents technological changes concerning not only the method of construction, but also the materials used. Another aspect is the methods of calculating the load-bearing capacity and settlement of piles. With acceptance for use the PN-EN:1997-1:2008 standard in 2010, it was necessary to change the approaches applied that based on many years of experience and tradition. The best method in this case is to forecast the full load-settlement characteristics. On the basis of the collected data, a comparative analysis of particular displacement piles technologies was made. The usefulness of individual methods of load-bearing capacity calculation depending on the pile technology was determined.

Laboratory-scale model studies on bearing characteristics of junked tires encased slags pile composite foundation

Junked tires encased slags pile composite foundation (JTES pile composite foundation for short) is a new method for treating soft soil ground. To study the vertical load-settlement characteristics and load-transfer mechanism of JTES pile composite foundation, vertical static load comparison tests in different loading conditions were investigated herein. The test results show that, the load-settlement curve of the JTES pile composite foundation changed slowly. And compared with the uncovered equal section slag pile composite foundation and natural foundation, its ultimate bearing capacity increased about 22.2% and 57.1%, respectively. While settlement of JTES pile composite foundation was reduced by 12.2% and 23.1% compared to that of the other two foundations. The axial force and lateral friction resistance of JTES pile were abruptly changed. The abrupt change rates of axial force of JTES piles were 35.4%, and the lateral friction with change rate of 40.8%. The pile-soil stress ratio of the JTES pile composite foundation was in 2 ∼ 4. Then, the calculated settlements of JTES pile composite foundation were proposed. The difference between model test results and calculation values was about 10%. The results can provide important references for the design and construction of JTES pile composite foundation in soft soil improvement.

A Review on Interaction Effect of Pile under Vertical Compression

The present theories and methods for design of the vertically loaded pile foundations generally provides the overall values of bearing capacity and settlement characteristics for the pile groups. In every design criteria for vertically loaded pile system, there are some factors affecting on major scale such as bearing capacity, Settlement, skin friction etc. This review paper shows that the consequences of vertical load on pile foundation done by various researchers and from their results help in predicting the load–settlement behavior of vertically loaded pile and pile groups. It is observed, when the group efficiency is close to unity, the variation between expected and observed behavior of piles proves to be a positive approach towards the ultimate load. Hence, various researchers have tested and published their laboratory and theoretical values on load-settlement characteristics under the influence of vertical load on pile foundation. This paper illustrates about comparison of various test results and their research gap on consequences of vertically loaded pile foundation.

Interference of two closely spaced footings embedded in unreinforced and reinforced soil medium: a finite element approach using ABAQUS

The stress or the failure zone of footings placed at close proximity interfere altering the performance of the footings. The present study pertains finite element analysis of two closely spaced rough, rigid strip footings embedded in cohesion-less foundation soil medium using the commercially available software ABAQUS. The interfering footings are considered to be supported on homogeneous reinforced and unreinforced soil medium. The failure criterion of the soil is directed to follow Mohr–Coulomb criterion with the non-associated flow rule. The influence of interference phenomenon on the ultimate bearing capacity, settlement and load-settlement characteristics have been explored by considering and varying the various parameters such as depth of embedment, soil friction angle, depth of reinforcement (first layer and subsequent layer), number of reinforcement layers and length of reinforcement. The soil friction angle is one of the important factors to have an effect on bearing capacity, and the friction angle is varied between 20° to 40°. The ultimate bearing capacity of closely spaced footings over unreinforced and reinforced soils are represented by non-dimensionless efficiency factors (ξUR and ξR). The analyses results conclude that interference has a significant influence on bearing capacity and settlement of footings supported over unreinforced and reinforced soil medium. Although, soil friction angle affects the interference significantly (higher friction angle has the highest peak of efficiency factor), depth of footing embedment also has remarkable influence over the same. The peak of efficiency factor decreases with an increase in the depth of footing embedment for a specified soil friction angle; however, the same increases with increase in soil friction angle for a specified depth of footing embedment. The interference effect is found to be decreasing with increase in the embedment depth. The bearing capacity of interfering footings on reinforced soil is enhanced noticeably compared to that on unreinforced footings; however, the settlement is not predominant.

Load-Settlement Characteristics of Tropical Red Soils of Southern Nigeria

This study investigated the relationship between the load-settlement curves obtained from field (in situ) plate load test under static loading conditions to those obtained from finite element (FE) analysis, for tropical red soils. Three test locations were selected within the University of Benin campus in Benin City, Nigeria. Laboratory tests were conducted on samples obtained from these three locations to obtain the index and strength properties of the soil, and these were used as input parameters for the FE analysis. The FE analysis was performed with PLAXIS 2D, using Mohr-Coulomb soil model as the constitutive model. Comparison of load-settlement curves obtained from the field plate load test with those obtained from the FE analysis showed that the FE tool was able to predict the ultimate vertical displacement for all three test locations, with good accuracy. The maximum vertical settlement obtained for Site A from the field plate load test was 8.79 mm, while that obtained from FE analysis was 9.02 mm. For Sites B and C, it was 12.77 mm vs 12.30 mm and 22.85 mm vs 22.30 mm respectively. Parametric studies were also conducted in order to evaluate the effect of variations in soil conditions on the static response of the soils. Results from the water table parametric analysis showed significant increase in vertical displacement as the soil immediately below the footing gets saturated. The results also showed that c and ϕ have significant influence on the load-settlement curves under static loading.

Load-Settlement Characteristics of Tropical Red Soils of Southern Nigeria

This study investigated the relationship between the load-settlement curves obtained from field (in situ) plate load test under static loading conditions to those obtained from finite element (FE) analysis, for tropical red soils. Three test locations were selected within the University of Benin campus in Benin City, Nigeria. Laboratory tests were conducted on samples obtained from these three locations to obtain the index and strength properties of the soil, and these were used as input parameters for the FE analysis. The FE analysis was performed with PLAXIS 2D, using Mohr-Coulomb soil model as the constitutive model. Comparison of load-settlement curves obtained from the field plate load test with those obtained from the FE analysis showed that the FE tool was able to predict the ultimate vertical displacement for all three test locations, with good accuracy. The maximum vertical settlement obtained for Site A from the field plate load test was 8.79 mm, while that obtained from FE analysis was 9.02 mm. For Sites B and C, it was 12.77 mm vs 12.30 mm and 22.85 mm vs 22.30 mm respectively. Parametric studies were also conducted in order to evaluate the effect of variations in soil conditions on the static response of the soils. Results from the water table parametric analysis showed significant increase in vertical displacement as the soil immediately below the footing gets saturated. The results also showed that c and ? have significant influence on the load-settlement curves under static loading.

Long-term time-dependent load-settlement characteristics of a driven pile in clay

This paper proposes a theoretical method to estimate the long-term time-dependent bearing characteristics of a driven pile. The viscoplastic behavior of the surrounding soils is described by nonstationary flow surface (NSFS) theory. The evolution of the soil behavior due to aging is incorporated in a skin friction softening model, which is used in the load-transfer method to predict the bearing capacity evolution of a driven pile. Extensive comparisons with experimental data are performed to illustrate the effectiveness and accuracy of the theoretical method. Both the proposed method and the experimental data show that the bearing capacity of the test piles increases by 30–50% due to the aging effect. The good agreement indicates that the long-term capacity evolution can be evaluated using the proposed method.

Model Studies on Load-Settlement Characteristics of Coarse-Grained Soil Treated with Geofiber and Cement.

This study aims to verify the effectiveness of fiber reinforcing with and without cement on settlement controlling of subgrade models, and to investigate the effect of fiber reinforcement on the load-settlement behavior of subgrade models. To this end, laboratory subgrade model tests were conducted under different static vertical loads. Three subgrade models composed of different fillers were constructed in a rigid concrete tank, and the internal earth pressures and settlements at different depths were measured through an earth pressure cell and settlement plate. Results show that the fiber-reinforced model keeps a slight difference to the unreinforced model in terms of earth pressure distribution under lower applied surface pressure. However, the earth pressure at various locations under each surface pressure was obviously lower than that of the other two models due to the combined effect of fiber and cement. In addition, for the unreinforced subgrade model, the 60 cm settlement domain was restricted within 40 cm depth through fiber-cement and fiber reinforcing, and the total settlement under 100 kPa was decreased by 48.5% and 30.8%, respectively. Moreover, reinforced models present with different settlement deformation features. The inflection points, after which the rate of settlement decreased with increasing applied surface pressure, were observed in the pressure-settlement curves. Under 200 kPa, the fiber-cement and fiber reinforcement decreased the total settlement of the unreinforced model by 61.4% and 34.7%, respectively. The greater applied surface pressure, the more efficient was fiber-cement reinforcing in settlement controlling.

Load-settlement characteristics of large-scale square footing on sand reinforced with opening geocell reinforcement

This paper describes load-carrying characteristics of a series of large-scale steel square footing tests performed on sand reinforced with two types of reinforcement methods. These are full geocell reinforcement (FGR) and geocell with an opening reinforcement (GOR). A thick steel square plate with 500 mm by 500 mm dimensions and 30 mm thickness was used as foundation. The parameters varying in the tests include the depth of geocell mattress (u), width of opening in geocell in the GOR type (w), relative density of sand (Dr) and number of geocell layers (N). The results revealed that the use of GOR and FGR methods enhances significantly the footing load carrying capacity, decreases the footing settlement and decreases the surface heave. It has been found that the use of GOR with an opening width of w/B < 0.92, has the same improvement effect on the footing load-carrying response as the FGR has (B = footing width). Furthermore, with increasing the number of geocell layers from 1 to 2 in both GOR and FGR methods, the footing bearing pressure increases and footing settlement, surface heave and difference of performance between FGR and GOR mattress decrease.

Bearing capacity of circular footing supported on coir fiber-reinforced soil

A series of triaxial compression tests on sandy soils reinforced with varying percentages of coir fibers have been numerically simulated to observe its effect on the elastic properties and friction angle of the sand. Test results indicated that with increase in fiber content, the elastic properties and friction angle of soil improved significantly. Three dimensional numerical investigation has also been carried out to investigate the load settlement characteristics of a circular footing resting on fiber-reinforced sand using the properties obtained from the triaxial simulations. This study provides an insight into the effectiveness of addition of coir fibers in the sand of different strengths on the bearing capacity of circular footing.

Treatment of Iraqi collapsible soil using encased stone columns

This study examined the load-settlement characteristics and mechanism of failure of a footing-type foundation resting on untreated soil, soil treated with an ordinary stone column (OSC), and soil treated with an encased stone column (ESC) into artificial loess deposits subjected to inundation. The investigation was carried out by means of conventional geotechnical laboratory work and the electrical resistivity tomography method. In addition, an analytical solution using a MATLAB script was presented to determine the load carrying capacity of the reinforced foundation and to validate the experimental results. Outcomes of the physical model demonstrated the efficiency of using an encased stone column over the ordinary stone column and the untreated collapsible soil. Results of the resistivity tomography system offered a valuable window into the soil-column interface. The soil conductivity was very sensitive to load and moisture variations during collapse. The analytical model illustrated that the enhancement in the ultimate bearing capacity of the reinforced column is influenced in proportion to variations in both the degree of saturation and matric suction. It increases with increasing the tensile strength of the geotextile and the angle of internal shear resistance of the fill material. However, it decreases when the diameter of the column expands.

BEHAVIOUR OF PRESTRESSED GEOTEXTILE-REINFORCED FINE SAND BED SUPPORTING AN EMBEDDED SQUARE FOOTING

This paper presents the results of laboratory model tests carried out on embedded square footing supported on geotextile reinforced sand bed. The effect of reinforcement with geotextile were studies through a series of laboratory model tests with different size of geotextile and depth of placement below footing. The effects of prestressing the geotextile on the strength improvement and settlement reduction of a reinforced sand bed are also being investigated. The model steel tank of size 120 cm x 50 cm x 50 cm and square footing of 10 cm are used. The study also highlights the effect of size of geotextile and placement of geotextile below footing on load-settlement characteristics.