Bearing Capacity Of Composite Foundation Research Articles

Research on the Reinforcement Effect and Bearing Characteristics of High-Pressure Jet-Grouting Piles on Covered Road Composite Ground in Landfill Sites

There is a notable difference between garbage pile foundations and general site foundations; due to their uneven particles, complex structure, and diverse composition, there are relatively few cases that can be used for reference. In this study, with the aim of renovating a landfill in Shenzhen, bearing-layer reinforcements were introduced in the overlying road of a garbage heap dominated by construction waste. The bearing capacity of a single-pile composite foundation was studied through a core-pulling test of high-pressure jet-grouting piles, a static load test of the bearing capacity of the single-pile composite foundation, design estimation, and numerical analysis. The results show that the obtained eigenvalue of the design estimate was 267.8 kPa, and the eigenvalue of the field test was between 182.58 kPa and 196.89 kPa, meeting the design requirement of an eigenvalue of no less than 175 kPa. The bearing capacity of the composite foundation of the single jet-grouting pile was analyzed using the ABAQUS numerical simulation software; the characteristic value of the bearing capacity of the single-pile composite foundation was 186.01 kPa, and the variation trend of its settlement–load curve was the same as that of the field test results, which met the design requirements. High-pressure jet-grouting pile technology has achieved remarkable results in the reinforcement of foundations that are mainly composed of construction waste.

Long-Term Bearing Capacity of Concrete Pile Composite Foundation under Composite Salt Erosion

In order to study the long-term bearing capacity of concrete pile composite foundation in the Salt Lake area, based on the Tehran Isfahan high-speed railway project in Iran, the full (semi) immersion drying test and rapid freeze-thaw test was carried out, and the specimens were scanned by electron microscope. Numerical calculations were used to study the effects of different pile strengths and design parameters on the long-term bearing capacity of the composite foundation. The main conclusions were as follows: The concrete specimens in the adsorption zone deteriorated earlier and faster. In the rapid freeze-thaw tests, the strength attenuation of high-strength (C40, C50) specimens was smaller than that of low-strength specimens (C20). Within 20 years after construction, the additional settlement of low-strength (C20) piles was 12.21 mm, while high-strength concrete was less affected by deterioration. With pile spacing ranging from 1.8 m to 4.5 m, the maximum increase in additional settlement under the C20 condition was about 20 mm. The pile-soil stress ratio under the three conditions increased by 2.42, 6.59, and 8.63. As the pile length and diameter increased, the peak stress of the pile body moved towards the pile end, and the changes in the pile-soil stress ratio under the three conditions were similar.

The Application of Soft Foundation Treatment of Cement-soil Mixing Pile in Zhangzhuang Pumping Station

The text introduces the process of comparison and selection of foundation treatment scheme, combining with example of foundation treatment in Zhangzhuang pumping station, and elaborates the detailed design steps and calculation way of cement-soil mixing pile,the economy benefits is very significant through settlement check, composite static load test, static load test of single pile, the bearing capacity of composite foundation meets the design demand.

Model test on bearing capacity of cemented slurry reinforced pile composite foundation

This study introduces the Geosynthetic Encased Prestressed (GEP) cemented slurry pile technology to address the challenges posed by waste slurry and dredged soil during infrastructure, urbanization, and underground space development. Laboratory model tests were conducted to assess the influence of prestress and geogrid on the bearing capacity of cemented slurry reinforced piles composited foundation. Results indicate that compared to non-geogrid pile composite foundations, both prestressed and non-geogrid pile composite foundations exhibited enhanced load-bearing capabilities in later stages, with an approximate increase of 25.89%. Additionally, the presence of geogrid effectively reduced settlement in the composite foundation under varying loads. The application of geogrid casings to seal cemented slurry reinforced piles facilitated load transfer downwards, restrained lateral expansion deformation, mitigated pile cracking, and bolstered bearing capacity. Consequently, a bearing capacity calculation equation for the composite foundation of cemented slurry reinforced piles was developed in this study. Parameter analysis demonstrated that higher geogrid tensile strength, smaller aspect ratio, greater cohesion, and internal friction angle of pile filler contributed to increased bearing capacity of cemented slurry reinforced piles. In summary, this study evaluates the viability of GEP cemented slurry piles and the impact of relevant parameters on pile bearing capacity of composite foundation. The findings offer valuable insights for practical engineering applications, advancement of eco-friendly transportation, and fostering sustainable development.

Comparison between bearing characteristics of pervious concrete pile composite foundations with different replacement ratios

The replacement ratio is an essential factor in evaluating the bearing capacity characteristics of composite foundations. This study focuses on the bearing capacity of a pervious concrete pile with different replacement ratios. The axial force, skin friction, and settlement were evaluated using a model test to assess the performance of the pervious concrete pile composite foundation. When the replacement ratio was reduced from 9.26% to 2.32%, the characteristic bearing capacity value was only 14%. Therefore, it may be unreasonable to use the settlement ratio method to evaluate this composite foundation's bearing capacity in a model test. Appropriate loading can significantly improve the bearing capacity of a pervious concrete pile composite foundation with a low replacement ratio. The pile–soil stress ratio exhibited different decreasing ranges in the later loading stage. As the load increased, the axial force of the pervious concrete piles was small and nonobvious, and the average side friction resistance of the piles in the foundation with a lower replacement ratio slowly increased.

Research on Application of CFG Pile Composite Foundation Bearing Capacity Detection Technology

Research on Application of CFG Pile Composite Foundation Bearing Capacity Detection Technology

Design and Calculation Method for Composite Foundation Using Large-diameter Rigid Piles in Pebble Bearing Soil

In the composite foundation using rigid piles, large pile-soil stress ratio often results in insufficient exploitation of bearing capacity of soil among piles. The rigid piles bear most of the vertical loads which makes the stress mechanism similar to that of pile foundation and fails to save cost. Based on the test and study of pile shaft resistance and tip resistance in the composite foundation using large-diameter rigid piles in pebble bearing soil and the stress monitoring of pile top and soil among piles, the pattern of variation in pile-soil stress ratio of composite foundation using large-diameter rigid piles was achieved. Furthermore, according to field test, use of cushion would lower the stress in rigid piles and exert bearing capacity of soil among piles which leaded to higher bearing capacity of composite foundation and smaller differential settlement. In contrast to “Technical Code for Ground Treatment of Buildings” (JGJ79-2012), a new design and calculation method for composite foundation using large-diameter rigid piles in pebble bearing soil was proposed based on the results from field test, numerical simulation and theoretical analysis. This improved and practical method has fully considered the potential bearing capacity of soil among piles and has been verified through practical engineering cases.

In situ evaluation and analysis of improvement effects of pervious concrete pile on alluvial silt ground

ABSTRACT Since the concept of pervious concrete pile (PCP) was put forward as a technology of ground improvement, some numerical simulations and small-scale tests have been performed to study the properties of PCP composite foundation. However, this technology has not been implemented in field. In this work, PCPs were installed by employing the method of vibrating-sinking tube and a series of tests are performed to evaluate the properties of PCP composite foundation. The tests on pile cores indicate the method of vibrating-sinking tube is suitable for installation of PCP. Compared with gravel column and soil-cement mixed pile, PCPs significantly increase the time rate of consolidation, improve the bearing capacity of composite foundation and increase pile-soil stress ratio. PCPs can also effectively reduce the acceleration and excess pore water pressure induced by vibration, and thus mitigate liquefaction of ground and reduce the damage of upper structure. This work is helpful for the design and installation of PCP.

Experimental study on horizontal bearing capacity of enlarged cap-group pile composite foundation

In order to provide reference for the engineering design in the area with large wind, water flow and other horizontal loads, the experimental study on the horizontal bearing capacity of composite foundation under three different working conditions was carried out in this paper, which includes cap-single pile, cap-9 piles and enlarged cap-9 piles. The results show that under the condition of cap-9 piles, the group pile effect coefficient is 1.17, and the load sharing ratio of the back piles is the largest, and the middle and front piless decrease sequentially. Also, with the increase of horizontal load, the load sharing ratio of the back pile increases while the middle and front piless is decremented. Under the condition of enlarged cap-9 piles, the group pile effect coefficient is 1.36, which is 16.24% higher than that of the cap-9 piles, which means the horizontal resistance is obviously enhanced. At the same time, compared with the cap-9 piles, the load sharing ratio of the back pile is reduced while the middle and front piless is increased, which means the stress of pile body tends to be more uniform.

Bearing capacity of composite foundation consisting of T-shaped soil-cement column and soft clay

Abstract The T-shaped column is a soil-cement column with two diameters, which is installed by foldable deep mixing blades for soft clay treatment. As a variable-diameter column, its design method is not well established, and this study focuses on the bearing capacity of composite foundation consisting of T-shaped columns and soft clay. A laboratory model test was employed to study the bearing capacity, stress distribution, and failure mode of the composite foundation. Twelve full-scale loading tests were performed in the field to study the geometrical parameters of composite foundation affecting on its bearing capacity. The experimental results indicated that the bearing capacity of composite foundation increased with increasing of the cap length and column diameter, and decreasing of the column spacing. The experimental results also revealed that the column failure might occur at the small-diameter column just below the column cap, which then led to the soil failure nearby. By including this additional failure mode, the design method for conventional column was adapted to estimate the bearing capacity of composite foundation consisting of T-shaped column and soft clay, and the method was validated by the experimental data.

Stress Analysis of CFG Pile Composite Foundation in Consolidating Saturated Mine Tailings Dam

Cement fly-ash gravel (CFG) pile is a widely used ground reinforcement technique. This paper aims to address the mechanical characteristics of CFG composite foundation in consolidating saturated mine tailings (MTs) dam. The field static load tests were employed to explore the bearing capacity of the CFG composite foundation, and finite element (FE) models in three dimensions validated through comparison with experimental results were used to discuss the pile-soil stress distribution and pile-soil stress ratio of the CFG composite foundation. The results indicate that the distribution of earth pressure and pile stress is relatively homogeneous and stable over depth and load, while the development of CFG composite foundation bearing capacity is insufficient, in which the developed bearing capacity of CFG piles is less than 50% of its characteristic value. Additionally, compared with the laboratory model test results, the pile-soil stress ratio decreases with the increasing of the load in FEM results proved to better conform to the actual engineering conditions. Furthermore, the deformation modulus and thickness of cushion exert significant influence on pile-soil stress ratio and integral bearing capacity of CFG composite foundation.

A Field Experimental Study of Composite Foundation with Rammed Soil-Cement Pile in Collapsible Loess Area

Natural foundation in loess areas is collapsible; however, composite foundation with rammed soil-cement pile can be used to meet the load requirements of the building. Immersion-compression test and field static loading test were carried out to measure the treatment effect. The test results showed that: the collapsible of loess foundation can be eliminated by treatment with rammed soil-cement pile when the loading pressure is between 200 to 500 kPa. Engineering properties of the foundation soil between piles are improved. The parameters improve more obvious with the pile spacing getting smaller. The bearing capacity of composite foundation increased to 291 kPa, compared with natural loess foundation. The research results can be applied to design and construction of compacted soil cement pile composite foundation in loess area.

Reinforcement Effect of Vibration Replacement Stone Column Test in Test Pile Area for One Crude Oil Business Reserve Base

The crude oil storage tank foundation is always treated by using vibration replacement stone column composite foundation treatment, mainly to improve the engineering properties of foundation soil and the deformation properties of soil, improving the bearing capacity of composite foundation, and to ensure the normal use of tank in the superstructure loads from damage or excessive deformation. Before construction to carry out the vibration replacement stone column composite foundation pile test, the test shows that strengthening the foundation bearing capacity characteristic value of vibration replacement stone column can meet the design requirements.

Study on the Design Method of Different Thickness-Diameter Ratios for Composite Foundation with Rigid Long and Short Piles

Composite foundation can be designed as long and short piles that lie on different bearing strata with high bearing capacities. Researches have shown that for foundation with sufficient stiffness, the ratio of the thickness of cushion to pile diameter (thickness-diameter ratio) plays an important role on the exertion of bearing capacities of pile and soil between piles. Traditional method just applies equal thickness-diameter ratio to design composite foundation with long and short piles, which hinders the exertion of bearing capacity of composite foundation. To overcome this defect, this paper studies the relations between thickness-diameter ratio and the exertions of bearing capacities of pile and soil between piles. The design method of thickness-diameter ratio for composite foundation with long and short piles is also proposed in this study.

Application of LS-SVM to Prediction of Bearing Capacity of Cement-Flyash-Gravel Pile Composite Foundation

There are a lot of factors that influence the bearing capacity of composite foundation, and the relationship between them is complex and nonlinear. Based on study of main factors that have great influence on bearing capacity of cement-flyash-gravel (CFG) pile composite foundation, the least squares support vector machine (LS-SVM) model of bearing capacity of composite foundation was established. The results show that the model has excellent learning ability and generalization and can provide accurate data prediction only with fewer observed sample. It is proved that the new method is a promising method for the determination of bearing capacity of CFG pile and other rigid piles composite foundation.

Numerical Study on the Bearing Capacity of Composite Foundation with Pile-Soil Shear Modulus

Numerical simulation model was established with FLAC3D to calculate the bearing capacity and the settlement of composite foundation with different pile-soil shear modulus. Then the rules of the effect of pile-soil shear modulus upon mixed pile composite foundation have been obtained. The results show that there is a great relationship between the pile-soil shear modulus and the bearing capacity of mixed pile composite foundation. Along with the increase of pile-soil shear modulus, the bearing capacity increase. Also, this paper suggest that the right value of pile-soil shear modulus of mixed pile composite foundation solidified by HEC or HAS consolidator dosing 12%, which can be used for the design of mixed pile composite foundation.

Bearing Capacity of Concrete-Cored DCM Pile Composite Ground

The concrete-cored DCM pile is an kind of composite pile by inserting the inner concrete pile into the DCM column socket. In two test sites, plate load test is used to measure bearing capacity of concrete-cored DCM pile composite ground. Vertical stress of surrounding soil and DCM column socket are measured by pressure cells. The axial force of precast core pile can be obtained by steel stressmeters which welded on the reinforcing steel along depth. The field tests results show that, the bearing capacity of concrete-cored DCM pile composite ground is much larger than that of original soil. The development degree of concrete-cored DCM pile bearing capacity in composite foundation increases steadily during the loading process. Both concrete-cored DCM piles and surrounding soils play an important effect on the bearing capacity of composite foundation.

Study on Calculation Method of Reinforced Embankment Bearing Capacity Based on Landslide Equilibrium Method

Foundation treatment is necessary when the construction is built on soft ground; Reinforcing is superior to many other methods when embankment is built on soft ground. This paper adopts slide block balance analysis of the composite foundation bearing capacity consisting of the horizontal reinforced and discrete material pile, while considering the level friction resistance from the reinforcement and ground on the foundation bearing capacity influence. and it is applied to practical engineering. The results show that the method is feasible.

Reliability Method and its Standard of the Composite Foundation Bearing Capacity

The general reliability analysis method of composite foundation bearing capacity was established with the example of cement injection pile, its limit state equation and the optimize method was presented, and the standard of reliability index was also proposed according to the corresponding demand of architectural structure. It indicate that the method is reasonable, convenient to calculation and can be popularized in the whole geotechnical engineering.

Cushion Impact on Bearing Capacity Exerting Degree of Soil between Piles for Rammed Cement-Soil Pile Composite Foundation

Basing on filed loading test results, the influences of cushion stiffness to the playing process of pile head and soil surface pressure in composite foundation was analyzed. Cushion stiffness will affect bearing capacity and failure mode of composite foundation with rammed soil-cement pile, which is applied in a relatively good ground. It point out that the cushion stiffness must be considered when loading test used to determine the bearing capacity of composite foundation with rammed soil-cement pile.