Bearing Capacity Of Single Pile Research Articles

Enhancing static load test of pipe pile composite foundation with innovative elastic cushioning technology

Pipe piles have been widely used in composite foundation treatment by virtue of the advantages of assembly line production, easy control of pile quality, fast construction, high bearing capacity of single pile and green environmental protection. By introducing elastic cushion in the static load test method of pipe pile composite foundation, and using theoretical analysis and field test to study the change rule of settlement, pile-soil stress ratio and pile top stress of pipe pile composite foundation with different cushion stiffness. It is concluded that it is feasible to replace the sand cushion layer recommended by the current specification with elastic cushion layer. The study shows that the elastic cushion method of static load test of pipe pile composite foundation is closer to the bearing state of real working condition. The elastic cushion has better pile-soil stress adjustment effect, which is more responsive to the stress adjustment effect of actual engineering cushion, and the elastic cushion provides an improved method for the static load test method of composite foundation.

Finite element simulation study on vertical bearing characteristics of single pile with ram-compacted bearing sphere.

The pile with ram-compacted bearing sphere (PRBS)is a kind of special-shaped pile, the calculation formula of single pile bearing capacity stipulated in Chinese Standards JGJ/T 135-2018 is relatively simple, and the factors considered are not comprehensive enough. This article uses the finite element simulation software ABAQUS to simulate and calculate the compressive bearing characteristics of PRBS, and studies the changes in the vertical bearing characteristics of PRBS under different factors and working conditions (different pile lengths, pile diameters, and the diameters of ram-compacted bearing sphere (RBS)). The calculation results indicate that the PRBS still has a large axial force near the enlarged end of the pile bottom, and the RBS bears a large load. The vertical bearing capacity of the PRBS is mainly provided by the RBS, but the pile side friction still has a certain degree of influence on its bearing capacity. The maximum ratio of pile side frictional resistance to applied load can reach 18.41%. Compared with the ordinary pile, the bearing capacity of the PRBS is significantly improved. The ultimate bearing capacity of the PRBS with the RBS diameter of 1m is more than 5 times that of the ordinary pile under the same condition. Pile diameter has little influence on the bearing capacity of PRBS, while the change of RBS diameter has great influence on the bearing capacity of single pile. However, when the RBS diameter is too large, it is easy to cause the uplift of surrounding soil in the construction process and affect surrounding piles. Therefore, it is suggested that the optimal RBS diameter should be 800mm~1200mm. This study provides reference suggestions for the study of piles with ram-compacted bearing sphere.

Research on the bearing behavior of single pile in self-weight collapsible loess areas.

The negative skin frictional caused by loess collapse will decrease the bearing capacity of single pile, which is essential to the design of pile foundations in loess areas. In this study, a method for estimating the subsidence of soil layer at any depth is firstly proposed based on the total self-weight collapse value. Secondly, a new load transfer constitutive model for pile-soil interface is developed, which considers the nonlinear stress-strain relationship and the ultimate shear strength of soil. Then, a load transfer calculation model for pile foundation is established, which can calculate the pile axial force, the pile skin frictional, neutral point position and the settlement of a single pile. The calculation results are compared with the test data that obtained from a pile foundation on-site immersion test and the effectiveness of the calculation method is verified well. This calculation method may be useful for designing pile foundations in collapsible loess regions.

Prediction Method of Vertical Ultimate Compressive Bearing Capacity of Single Pile in Soft Soil considering the Influence of Gravity

Considering that the pile foundation is widely used in soft soil, in order to improve the prediction accuracy of the vertical ultimate compressive bearing capacity of a single pile, this paper puts forward a calculation model of the pile side friction resistance in homogeneous soil based on the previous research and further deduces the calculation method of pile body internal force in layered soil under the influence of gravity field. In this research, the transmission of load along the pile body is related to the previous research on the ultimate end resistance, and an analytical calculation for the vertical ultimate compressive capacity of a single pile is proposed. The novelty of the method is that the ultimate bearing capacity is solved from the perspective of force transfer while considering its own gravity, making the results more accurate. In order to verify the reliability of the method, four engineering test piles in the soft soil area of Suzhou, China, were selected, and it is indicated that the results of the static load test and finite element simulation are consistent with the proposed method, proving that the method proposed in this paper for predicting the vertical ultimate compressive bearing capacity of single pile in soft soil area has an excellent effect.

Analysis on Bearing Behavior of Single Pile under Combined Action of Vertical Load and Torque in Expansive Soil

To reasonably analyze the bearing characteristics of curved beam bridge pile foundation under the combined action of vertical force (V) and torque (T) in expansive soil, a method of determining Tu (limit torque) under the action of V is proposed. Considering the effects of expansive force and ground heave after immersion, the load transfer function at the pile–soil interface with positive and negative friction resistance is established. The nonlinear solution of a single pile under vertical load is achieved by the finite difference method. Subsequently, the circumferential limit friction resistance is modified, and a loop iteration program is compiled through MATLAB. Thus, the bearing capacity of single pile under the loading path of V→T is obtained. The corresponding failure envelope curve is drawn and verified by laboratory model tests. Based on the verified solution, the bearing capacity envelope curve and deformation characteristics of single pile are analyzed. The influence of the expansion rate on the bearing capacity envelope curve is discussed, and reasonable engineering suggestions are put forward.

Dynamic Response Analysis of Pile Group Foundation of Super-Giant Sewage Treatment Structure on Hydraulic Fill Foundation

In this study, a 3D numerical model, considering the dynamic interaction between soil, pile foundation, and super structure, and the parameter analysis of internal force response of pile group foundation under differences seismic intensity, was established based on the Bangladesh sewage treatment plant project to investigate the dynamic response of pile group foundation of liquid-containing structures. The results show that the internal force of pile gradually increases with time, and the horizontal dynamic displacement peak value appears earlier under different seismic wave responses and seismic intensity. With the increase of seismic time history, the variation degree of dynamic impedance with frequency and impedance peak will increase. The pile group effect and single pile bearing capacity of foundation in hydraulic fill fine sand and silty clay were verified. By comparing numerical simulation and theoretical calculation, the results show that the pile group foundation exerts the soil squeezing effect after pile construction is completed, and the dynamic elastic modulus of the soil layer can be increased. Simultaneously, the soil layer will have a better integral stiffness. The pile group effect coefficient obtained by the solid perimeter method is most consistent with the numerical simulation method.

Experimental Study on the Force Characteristics of Superlong Pile Groups in Silty Sand

Laboratory model testing of single pile and superlong pile groups in saturated silty sand was conducted to investigate the response and bearing behavior of superlong pile groups with a high or low cap under vertical loads. The load transfer mechanism and bearing behavior of the pile shaft were discussed in detail. The load-settlement curve of the loaded superlong pile groups belongs to the type of gradual descent in silty sand. The transferred load decreased along the pile length during loading, but the gradients differed in different positions of the superlong pile group foundation with a high or low cap. The maximum shaft friction of the superlong pile groups with a high and low cap is about 2.5 times and 1.8 times, respectively, than that of the single pile. In addition, the tip resistance of the piles in the pile group foundation is about 2–3.5 times that of the single pile. The friction resistance of the superlong pile group foundation with a low cap was slightly larger than that of the high cap in the entire pile length, and two peaks and one peak, respectively, were observed. Under the ultimate load, the pile-soil maximum relative displacement of the friction on the pile side in the silty sand stratum was about 3% of the pile diameter. Under the ultimate load, the load sharing ratio of the pile side resistance of the two types of pile group foundations was about 60% of the total load. The load sharing ratios at the pile tip of the superlong pile groups with high and low caps are 40% and 33%. Furthermore, equations were proposed to determine the axial capacity of the superlong pile group based on the single pile bearing capacity and were applied to analyze the test pile. The calculated ultimate bearing capacity was similar to the measured value, with a maximum error of only 4.88%, thus validating the proposed method.

The macroscopic and mesoscopic study on strengthening mechanisms of the single pile with raft under pile-soil-raft combined interaction

Previous studies found that the ultimate bearing capacity of single pile with raft (SPWR) is greater than the sum of the ultimate bearing capacities for single pile and raft foundation. However, the mechanism of this strengthening mechanism is still unclear. This paper studies the bearing capacity characteristics of three different foundation models (i.e., SPWR, single pile and raft foundation) through laboratory tests and discrete element method (DEM) simulations. Specifically, in laboratory tests, the analysis of displacement contour map is conducted to explain the macroscale strengthening mechanism. Subsequently, in DEM simulations, the deformation, force chain and stress transmission of three foundation models are examined, aiming to reveal the mesoscopic strengthening mechanism. The results show that the wedge-shaped elastic core is observed under the raft of SPWR, which is a key element in the strengthening mechanism. On the one hand, the elastic core can strengthen the compactness of soil near the pile side and pile end, which improves the lateral friction resistance and the end bearing capacity of SPWR. On the other hand, the elastic core can increase the range of disturbance to the SPWR, which makes a larger range of soil to bear the load.

Analisis Desain Pondasi Strauss Pile Pada Bangunan Rumah Sederhana Gunung Anyar Surabaya

Construction of a simple 2-story house located in Gunung Anyar, Surabaya with conditions based on an investigation of 19 m deep clay soft soil. The selection of the Strauss Pile Foundation based on the type of soil and building is simple. The calculation of the carrying capacity is calculated based on the Sondir data using the Meyerhoff method. The calculation of the settlement is carried out with an immediate and a consolidated. The calculation of the carrying capacity of the Strauss Pile is using the Meyerhoff method with variations in the diameter of the Strauss pile 20 cm, 30 cm, 40 cm to a depth of 10 m. The selected single pile selected at a depth of 7 m diameter 40 cm has an allowable carrying capacity value of 4.06 tons. From the results of the loading input on the residence using SAP 2000, the maximum load is 20.99 tons. Based on the single pile bearing capacity, the maximum load is 7 piles. Calculation of group piles obtained an efficiency value with 4D uniform pile spacing of 0.82% and a large decrease of 8.5 cm. From the decrease obtained, it still fulfills the decrease in the decrease of 15 cm based on the U.S.S.R

Study on Bearing Mechanism of Split Grouting Pile Based on Finite Element Simulation

In order to realize the directional and controllable splitting of splitting grouting, the field grouting test was carried out. Using a new grouting pipe designed, the splitting direction and size of the branch vein are effectively controlled through the control of grouting pressure and grouting amount. In order to explore the bearing characteristics of split grouting pile and provide necessary parameters for the design of split grouting pile composite foundation in engineering practice, the field static load test and indoor geotechnical test of split grouting pile are designed, and the ultimate bearing capacity of single pile and necessary soil parameters are obtained. In order to make up for the limitations of field static load test, the three-dimensional finite element model of pile, soil and branch vein of split grouting pile is established by using the finite element analysis software ABAQUS. The finite element analysis results are compared with the measured values of field test, and the variation laws of pile shaft axial force, stress and displacement of branch vein at different depths, pile side friction, etc. are further explored, Through these changes, the interaction and load transfer mechanism between pile and soil are analyzed, which provides a reference for optimal design.

Model Test Study on Deformation of Snowflake Shaped Steel Sheet Pile Based on OFDR.

As a newly developed pile foundation, the snowflake shaped steel sheet pile is composed of three Y-shaped sections with an included angle of 120° and has a large specific surface area, which can give full play to the side friction of pile and improve the bearing capacity of single pile. At the same time, the snowflake shaped steel sheet pile has a high strength, relatively few materials, and it has good prospects with engineering applications. In order to accurately grasp the mechanical characteristics of the snowflake shaped steel sheet pile, this paper carried out the model test of snowflake shaped steel sheet pile based on OFDR (optical frequency domain reflector) distributed optical fiber sensor technology. The results show that: (1) OFDR distributed optical fiber sensing technology can effectively monitor the strain of snowflake steel sheet pile; (2) under the vertical load, the strain of snowflake steel sheet pile decreases along the length of the pile; (3) the strain of the same section of snowflake steel sheet pile is different at different positions, the strain at the junction between web and web is basically the same as the junction between web and flange, and the strain of the pile shaft on the flange edge is larger.

In Situ Test Research on Friction Resistance of Self-Anchored Test Pile

The traditional static load test method has been considered as the most direct and reliable method to determine the bearing capacity of single pile, but it has some disadvantages, such as inconvenient operation, laborious test, high cost, and being time-consuming. In this paper, a new type of pile testing method, self-anchored pile testing method, was proposed, and the in situ test was carried out for the first time. This method allows the upper and lower piles to provide force to each other and does not occupy other construction spaces. It had the advantages of simple operation and being economical and practical. Based on the Q-w curve, axial force distribution curve, and hyperbolic function model of load transfer, this paper studied the evolution law of friction of self-anchored test pile and the load transfer process of self-anchored test pile. The results show that the load transfer process of self-anchored pile-soil interface can be divided into three stages: elastic, elastic-plastic, and limit state. The friction of the upper and lower piles starts from the bottom of each pile and then gradually increases. The soil around the upper and lower piles gradually undergoes nonlinear deformation and shear failure, and the pile soil reaches the yield state. By analyzing the hyperbolic function model of load transfer, it shows that the hyperbolic function model can be better applied to the self-anchored test pile, which has reference value for the selection of the function model of self-anchored test pile in the future.

Experimental Study on Base Piles Bearing Capacity of Qilu Yellow River Bridge

Qilu Yellow River Bridge is located in Jinan City, Shandong Province. The main bridge adopts bored pile foundation with high design bearing capacity. In order to ensure that the bearing capacity of single pile meets the requirements and ensure the safety of the bridge, the double load boxes O-cell test pile method is used to test the bearing capacity of pile before and after grouting. According to the soil layer property around pile, the double load boxes can be loaded optionally and solve the problems in the tradition pile test. The bearing capacity of each pile section is determined. The bearing capacity of pile before grouting is 75255kN, the bearing capacity of pile after grouting is 89100 kN.

Pile Foundation Design and Analysis of Teaching Building in A High School

The foundation design should adhere to the principles of adapting measures to local conditions, using local materials, protecting the environment and saving resources. Based on the geotechnical engineering survey data, the design should be carried out by comprehensively considering the factors such as structure type, material situation and construction conditions. The pile foundation design is adopted in this project. includes the determination of pile end bearing layer and pile length, the determination of vertical bearing capacity of single pile, the calculation of pile number and pile layout form, the checking calculation of pile foundation bearing capacity and settlement, the design and checking calculation of pile body structure, the design and checking calculation of pile cap. Until all requirements of the specification are met.

Field test research on post-grouting effect for super-long cast-in-place bored pile in thick soft foundation

The field static load test method was adopted for two test piles in a project in Zhejiang area of China, analyze the effect of post-grouting technique on super-long cast-in-place bored pile and its internal mechanism. Q-s curves and pile axial force curves were drawn based on test data to show that post-grouting technique played a prominent role in improving bearing capacity of single pile and pile skin friction. In addition, pile skin friction at upper soil layer around super-long pile was fully used, but that at lower soil layer was not. For the design of super-long pile, the compression of pile body should be considered to make the best use of pile skin friction caused by relative displacement between pile and soil.

Experimental Study on Bearing Characteristics and Soil Deformation of Necking Pile with Cap Using Transparent Soils Technology

This paper will employ the transparent soil experiment technology to explore the influences of shallow necking on the vertical bearing capacity of single pile with cap. Model experiment is carried out on one intact pile and nine shallow necking piles. The load-settlement curves of all piles are obtained, which are used to study bearing characteristics of piles. The displacement fields of soil around piles are employed to investigate the reasons for the loss of vertical bearing capacity of piles with shallow necking. The vertical bearing capacity is greatly reduced which is caused by shallow necking. When the axial dimension of necking is the same, the larger the radial size is, the greater the loss of vertical bearing capacity is. When the radial dimension of necking is the same, the greater the axial size is, the greater the loss of vertical bearing capacity is. The soil near the pile shaft and under the pile cap produces a large area of vertical downward deformation, which causes the relative displacement between the pile shaft and the soil to greatly reduce. Therefore, it is easy that the necking piles with caps develop negative friction, which causes the vertical bearing capacity of piles to reduce. When the radial dimension of the shallow necking is 80% of pile diameter, the pile is easy to be damaged.

Engineering design and static load test of Soil filling pile with spiral cone foundation

This paper introduces the innovative soil filling pile with spiral cone technology, and through the soil filling pile with spiral cone foundation static load detection of phase 4 project of Bishui Gardens, Yanji City, Jilin Province, proposed the following design suggestions: When the diameter of the pile is 500mm, the length of the pile is 12-20m, the maximum settlement interval is 28.04 ∼ 44.85mm; the vertical ultimate bearing capacity of single pile is 3600∼4000KN. The pile can speed up the construction period, ensure the project quality and reduce the project cost. It has obvious technical advantages and has obtained good economic and social benefits. It is a new type of energy-saving and emission-reduction pile foundation with extensive application prospects.

An Optimization Algorithm for Exponential Curve Model of Single Pile Bearing Capacity

The ultimate bearing capacity of single pile is very important to engineering safety, so correctly predicting its value becomes an important part of engineering safety. Based on the traditional exponential curve model, a parameter optimization algorithm of the exponential curve model of single pile bearing capacity, which combines the golden section method and the linear least square method, is proposed. In order to verify the reliability of the proposed optimization algorithm, the measured data of the building engineering in the literature were optimized and calculated. Through comparison, it is found that the optimization algorithm is closer to the measured value than the traditional exponential curve model algorithm, which can better guide the engineering practice, and verify the effectiveness and superiority of the proposed parameter optimization method.

Comparison and analysis of conversion methods for self-balancing test of pile bearing capacity

The principle and method of self-balancing test are introduced briefly. In this article, through comparison of common Q-S curve of equivalent transformation to transform from the balance of the measured load-displacement curve for the traditional method of load - displacement curve, puts forward the advantages and disadvantages of each, through the three bored piles in static load test of pile reaction from balance to detect vertical compressive ultimate bearing capacity of single pile is in line with the requirements and compare the load-displacement curve after conversion. Some problems of the self-balancing method in engineering are pointed out, which is of certain reference value to the popularization and application of the self-balancing test of pile bearing capacity.

Bearing capacity assessment of bored piles equipped with expander body systems using the mechanics of unsaturated soils

Bearing capacity of single piles are occasionally predicted using the renowned theoretical methods (α and β methods). These methods are based on laboratory tests, which can be time-consuming, but also applicable in foundation engineering practice for unsaturated soils. Full-scale pile load tests were carried out on bored piles equipped with Expander Body Systems in the Federal District of Brazil, known for its unsaturated, collapsible and porous soil. This paper has the aim to assess the applicability of the β method, considering the contribution of soil matric suction, in order to estimate the bearing capacity of these piles subjected to uplift and compression loads in unsaturated soils. Based on the experimental results, it is indicated that the use of the β method considering the matric suction, can be a useful tool for bearing capacity estimation of bored piles equipped with Expander Body Systems in unsaturated soils.