Uplift Bearing Research Articles

Numerical modeling the uplift bearing capacity of transmission line tower foundation on expansive soil

To solve the energy shortage problem, transmission lines are widely built in the middle-west of China where the expansive soil is widely distributed. The transmission tower foundation may suffer wetting and shrinking load due to weathering. To solve this problem, consolidated undrained shear tests are conducted to obtain the mechanical behavior of expansive soil with different water content. The bearing behavior of pile foundation and plate foundation under uplift force are simulated by finite element method. The bearing capacity, axial force and lateral friction of pile foundation are analyzed. The bearing capacity of plate foundation is also investigated. These obtained numerical results can provide a good reference for the design of transmission line tower foundation when it is located in an expansive soil area.

Numerical Analysis of Uplift Bearing Behavior of Vortex Squeezed and Expanded Piles

Numerical Analysis of Uplift Bearing Behavior of Vortex Squeezed and Expanded Piles

The Study on Structure Design and Bearing Behavior Simulation of Pier Foundation for Variable Cross-Section and Post-installed Fastening by Spiral Spray Indentation

According to the stress characteristics of pier foundation, the research designs a structure of pier foundation for variable cross-section and post-installed fastening by spiral spray indentation, and its mechanical characteristics and construction technology is analyzed. By means of finite element analysis, structure of pier foundation for variable cross-section and post-installed fastening by spiral spray indentation and conventional pier foundation structure in vertical compressive bearing capacity and uplift bearing capacity of differences are analyzed. It is found that the new design structure is better than the conventional pier foundation, and the vertical load-bearing capacity and the load bearing capacity are improved, and the new design structure engineering benefits are verified.

Research on Uplift Bearing Performance of Assembled Steel Pipe Pile used in Transmission Lines in Mountainous Terrain

Assembled steel pipe pile, which is a novel pile foundation, is developed in the paper. The ultimate uplift bearing capacity of the pile is proposed, and simulation by Plaxis3D and the corresponding experiment are performed to verify the theory. In the simulation, ultimate uplift bearing capacity of the assembled steel pipe pile and ultimate lateral frictional resistance of the interface of pile-soil increases with the increasing of the strength and stiffness of the interface of pile-soil, and with the increasing of length-diameter ratio, ultimate uplift bearing capacity of the assembled steel pipe pile increases while the ultimate lateral frictional resistance decreases gradually. The ultimate lateral friction is influenced by both of the strength of the soil around the pile and the interface of pile-soil, and the ultimate uplift bearing capacity obtained by simulation and theoretical calculation are close. Long-gauge FBG sensors are used in the experiment for measuring the longitudinal strain of the pile, and the error of ultimate uplift bearing capacity between the results of experiment and theory is less than 10%.

The effects of the geometric parameters of a circular shallow foundation on its uplift bearing capacity in loess soil

The effects of the geometric parameters of a circular shallow foundation on its uplift bearing capacity in loess soil

Uplift Test and Design Method for Bearing Capacity of Isolated Spread Concrete Foundation Slab with Large Width-to-Height Ratio

This paper is focused on the experimental study and numerical simulation of isolated spread concrete foundation slab with a large width-to-height ratio (in short ISCFS-LWR) to investigate the failure modes and uplift bearing capacity, as well as the design method of uplift capacity. First, a total of 16 isolated spread concrete foundation slabs with the width-to-height ratio varied from 1.5 to 4 and the hypotenuse slope varied from 10° to 30° were tested under uplift load. Based on the test results, effects of the width-to-height ratio and the hypotenuse slope on uplift bearing capacity of ISCFS-LWR were analyzed and discussed. Then, several numerical models were built using the finite element software ABAQUS and the results of numerical analysis agreed well with the test results. Furthermore, the cross-sectional performance of ISCFS-LWR was studied, and the coefficients of internal force arm were also evaluated further using previous validated numerical models. To obtain the suggested design method of uplift capacity for the foundation slab, effective width correction coefficientkand slope correction coefficientjwere introduced to propose a design formula. Finally, the proposed design method was applied to a practical engineering, and the economic indicators obtained from the suggested design method were compared with that from the original design method. The results of this paper showed that the correction coefficientjsksbased on numerical analysis agreed well with the recommended correction coefficientjk, and the error was between 1% and 3.4%, by which the reasonability of the proposed design method of uplift capacity for ISCFS-LWR has been proved. It can also be found that the economic benefits of the practical engineering in this paper were obvious due to the suggested design method, and this paper can provide a reference for other engineering practices and the further research work on ISCFS-LWR.

Axial Uplift Behaviour of Belled Piers in Coarse-Grained Saline Soils

Bearing capacity of belled pier foundation is critical in designing transmission lines in coarse saline soil region. This paper describes model test results on belled pier foundations. Axial uplift behaviours including failure modes, load-displacement curves, and ultimate uplift bearing capacity were discussed. The failure planes in four cases were obtained from pulled out cone-shaped bodies. An empirical equation was developed with a critical parameter of an uplift angle in design. Results indicate the range where the ground uplift shows circular extension at higher loads and the overall shear failure finally occurred. The load-displacement curves are primarily softening, and the uplift bearing capacity for coarse-grained saline soils (CSS) in the crystalline state increases at larger thickness, higher than that in dissolved state. Failure planes all exhibit approximately linear change from bottom to up. The angles of uplift for soils in crystalline and dissolved states can be taken as 34° and 18°, while 32° for the conventional for the sake of safety. Uplift behaviour of belled piers in CSS was modelled incorporating a practical interface model, with both failure planes and plastic range.

Uplift Behavior of Belled Short Piles in Weathered Sandstone

Field pull out test results of 500 kV double-circuit line of Luping-Fule are presented in this paper to investigate the uplift bearing behavior of rock-socketed belled short piles. A calculation model of rock-socketed belled short pile has been proposed. During the initial stage of loading test, uplift load is shared by even section and bell of the pile, and the bell continues to bear uplift load after the lateral resistance of even section pile reaches the limit. A different performance has been found on the case of long belled pile. At the ultimate state, the uplift resistance provided by bell accounts for about 54.9% and 34.7% of the total uplift capacity for the 6.0 m long and 7.0 m long piles, respectively. Increasing pile length has been found to noticeably increase the ultimate uplift bearing capacity, while it has less effect on the displacement of pile top. The uplift capacity of even section pile is associated with the shear strength of rock mass around the pile, and the test results demonstrate that the ultimate resistance can be equal to the shear strength. The calculation method proposed in this paper is proven to be able to accurately predict the ultimate uplift bearing capacity of the rock-socketed belled short piles.

Effect of combined translation and torsion on undrained uplift capacity of plate anchors: Plastic limit analysis (PLA) solution

Uplift capacity of plate anchors have been the focus of numerous studies, since anchor plates are designed for pull out in normal operating conditions. However, the response of plate anchors under six-degrees-of-freedom loading caused during extreme loading conditions is poorly understood. The purpose of this study is to propose a simple yet sufficiently accurate analytical solution to investigate the behavior of plate anchor under combined in-plane translation and torsion and to evaluate its effect on the plate uplift bearing capacity. To this end, a modified plastic limit analysis (PLA) approach is introduced and compared with limit equilibrium (LE) and simplified upper bound baseline solutions. The proposed method is verified with three dimensional finite element (3D-FE). The variables considered in this study include plate aspect ratio, plate thickness, as well as load direction and eccentricity. Results of analytical solutions indicate the insensitivity of the “shape” of the shear-torsion yield envelope to plate thickness. This finding facilitates the use of simplified yet reasonable yield envelope for infinitely thin plate obtained from simplified PLA approach for other plate thicknesses. The “size” of the failure envelope (controlled by pure torsional and translational capacity) could be predicted fairly accurately by PLA and LE methods. Combination of these analytical methods offers a simple yet reasonably accurate solution to describe shear torsion response of anchor plate. The obtained shear-torsion yield envelope is then fitted in the generalized six-degrees-of-freedom yield surface which describes the reducing effect of moment, torsion, and planar forces on the uplift capacity of plate.

Experimental and numerical analysis to determine the uplift capacity of piles in gravels

AbstractThis paper describes the process of testing and design of tension piles as fundaments of air‐supported structures for sports facilities. Two piles with different ratio between diameter and length are tested on axial static tensile load for designing purposes. The results are later compared with FEM numerical model. The obtained ultimate uplift capacity from site experiments is confirmed with the numerical model. The results from the numerical analysis regarding the shear and normal interface stresses are used to determine the soil‐pile friction angle δ. At the end, artificial neural networks were used to predict the uplift bearing capacity of piles with different geometry and soil conditions.

Study on effective anchorage length of anchor cable based on Gauss's function

In the current relevant codes and technical standards, the design of anchor cables (bars) is based on the assumption that the shear stress is distributed uniformly along the anchor segment. However, according to this assumption, the super-deep pit need a large uplift bearing capacity, which will lead to the long anchor segment and has great hidden danger in the actual engineering design. Therefore, this paper, based on the previous derived shear stress function between τ and the anchor length, we get a research suitable model-Gauss curve distribution model through the analysis of saturated clay drawing data, and strata anchor shear stress distribution is more suitable for the Gauss function model in saturated clay; at the same time, through the FLAC numerical simulation of Jinan Government Affairs Center project, we obtained the optimal anchor effective anchor length is about 10~12m, the foundation pit anchor is optimized.

Experimental Studies on Modified Suction Caissons in Fine Sand Subject to Uplift Loading

A modified suction caisson (MSC), which was reported by the authors of this paper previously, comprises an external short-skirted structure that is added to a regular suction caisson (RSC). It has been proved that MSCs can improve the lateral bearing capacity and limit the deflection of the caisson compared with RSCs. A series of model tests were conducted to investigate responses of MSCs subject to uplift loading in saturated sand. The effects of external skirt dimensions on the uplift bearing capacity of MSCs were considered. In addition, the influences of the sealed top lid of the skirted structure on the uplift bearing capacity and the resulting passive suction of MSCs were also studied. It was found that the uplift bearing capacities of MSCs are 1.4–1.7 times that of RSCs. Moreover, test results in serviceable conditions show that the sealed external skirted structure of perspex-made suction caissons significantly contributed to the uplift bearing capacity as a result of passive suction.

Analysis of uplift bearing capacity of pile based on ABAQUS

The uplift bearing capacity of pile in soil foundation is mainly obtained by load test, which is time-consuming and low-efficiency. A small sliding model and the contact pairs in large-scale finite element software ABAQUS are used to simulate the friction between pile and soil, and a good fitting curve of pile foundation bearing capacity is obtained. According to the results of finite element software, the lateral friction of the pile is fully developed, and the stress of the pile gradually reaches the ultimate pullup capacity with the increase of pile displacement. The finite element software ABAQUS can be used to simulate uplift capacity of pile.

Analysis of uplift bearing capacity of expanded pile

The research on the uplift bearing capacity of expanded pile is less, which lead to develop slowly of mechanism of expanded pile. The finite element software is used to simulate the bearing capacity of expanded pile, and the friction between the pile and soil is simulated by surface contact. The simulations show the ultimate bearing capacity and the distribution of side friction of the expanded pile. Along with the displacement moves bigger, the side friction of upper expanded pile is fully used. When the displacement moves to a special level, the side friction of whole pile is fully used. If the load is bigger than the 25000kPa, the expanded pile will be destroyed.

Theoretical Analysis of Influence on Bearing Plate Space for Uplift Bearing Capacity of the Single MEEP Pile

Though FEA software ANASYS, this paper establishes analysis model about work together with pile and soil, and analyzes bearing the influence on bearing plate space for uplift bearing capacity of the MEEP pile, and it is presented that a reasonable bearing plate space, which provides a reference for improving further uplift capacity theory of the MEEP pile.

Research on the Uplift Bearing Capacity of Suction Caisson Foundation under Local Tensile Failure

The research on the uplift bearing capacity is one of the important issues worth concerning and solving. For this reason a lot of studies about this aspect have been done by many scholars, but there are still no wide spread engineering specifications on design and calculation of uplift bearing capacity for suction caisson foundation. The quantitative calculation method on the uplift bearing capacity of suction caisson foundation under local tensile failure is proposed by the author. And the indoor uplift tests are carried out on the single-bucket suction caisson foundation models with different diameters and length-diameter ratios in the wet sand, by which the feasibility of this method is initially proved.

Analysis on the Impact of Bearing Plate Slope Angle on Uplift Bearing Capacity of the Concrete Expanded- Plates Pile

Analysis on the Impact of Bearing Plate Slope Angle on Uplift Bearing Capacity of the Concrete Expanded- Plates Pile

A Comparative Study of Concrete Expanded Plates Pile and Common Pile Uplift Bearing Capacity

A Comparative Study of Concrete Expanded Plates Pile and Common Pile Uplift Bearing Capacity

The Analysis of the Vertical Uplift Bearing Capacity of Single CEP Pile

By analyzing the existing calculating model of uplift bearing capacity of the CEP pile, the article put forward the deficiencies of the traditional calculating model for the uplift bearing capacity of the CEP pile, and according to the failure characteristics of soil and forced mechanism of pile of the CEP pile under vertical tension, it is put forward that the final calculation model of the uplift bearing capacity of the CEP pile, which provides reliable theoretical basis for the design and application about the type of pile.

Analysis of the Effect of the Space of the Bearing Plate on the Uplift Bearing Capacity of the Concrete Plates-expanded Pile

In this paper, using ANSYS FEM software to simulate the failure status of the concrete plates-expanded pile (CPEP) in clay, keeping the other parameters constant, and through changing the space of plate of the concrete platesexpanded pile to study the effect of the space of plate on the uplift bearing capacity of the concrete plates-expanded pile. Through the research of this paper to complete the influence factors of the uplift bearing capacity of the concrete platesexpanded piles, in order to provide theoretical basis to the application of the concrete plates-expanded pile in practical engineering.