Uplift Capacity Of Single Piles Research Articles

Utilization of enlarged base to improve the uplift capacity of single pile in sand—model study

Utilization of enlarged base to improve the uplift capacity of single pile in sand—model study

An experimental study of rough single pile and pile group under uplift loading in sand

Foundation systems of specific structures such as high-voltage power lines, communication towers, long factory chimneys, sea platforms, columns carrying the advertising boards and signs in freeways and railways are subjected to different loads. These structures are also under the influence of uplift load and the foundation systems should be designed according to the factors affecting the uplift capacity. In this study, the uplift capacity of a rough single pile and pile group embedded in sand is investigated, experimentally. The uplift capacities of a single pile and pile group configuration of 2 × 2 under the effect of various parameters such as pile embedment ratio (L/D), spacing ratio between the piles (S/D) and relative density of sand (Dr) are examined by using a rough steel pile in 25 mm diameter with circular geometry. Furthermore, it is aimed that the uplift capacity of each pile is determined by being connected a load cell to each pile in the group. The value of (S/D)opt is determined to be affected by the relative density of sand, and the interaction between piles eliminates in larger S/D in dense soil. It is observed that the uplift capacity increases considerably with the increase of all investigated parameters.

Uplift Capacity of Single Pile with Wing in Sand Numerical Study

Uplift Capacity of Single Pile with Wing in Sand Numerical Study

Uplift Capacity of Single Pile Embedded in Partially Submerged Sand

This article illustrates experimentally the effect of the groundwater level rising on the soil pile interaction under uplift load. A series of model test for piles embedded in partially submerged sand along pile depth under pull out loads were carried out. A rigid steel cylindrical cell measuring 315 mm inside diameter with 850 mm high was used as a sand container. Investigations were done by varying parameters as the ratio between groundwater height to embedded pile length (hw/L), pile stiffness (L/D), installation method and sand density. Results showed that there is a considerable decrease in the uplift capacity of the piles due to increase in the groundwater level. It has been found that the variation of the submerged pile length ratio from 0 % to 100 % leads to decrease in the uplift capacity as much as 60% of its initial value in dry condition.

Uplift capacity of single piles and pile groups embedded in cohesionless soil

Understanding the pile behavior and predicting the capacity of piles under uplift loading are important topics in foundation design. Experimental model tests have been conducted on single piles and pile groups embedded in cohesionless soil and subjected to pure uplift loading. The experimental tests were conducted on straight-shafted vertical steel piles with an outer diameter of 26mm in a steel soil bin. The tested piles have embedment depth-to-diameter ratios (L/d) of 14, 20, and 26. The sand bed is prepared at three different values of relative density of 75%, 85%, and 95%. Single piles and pile groups containing two, four, and six piles embedded in sandy soil were tested, and the results are presented and discussed in this paper. The influences of pile embedment depth, relative density of soil, and arrangement of piles in a group on the uplift capacity of piles are investigated. The study revealed that the behavior of single piles under uplift loading depends mainly on both the pile embedment depth-to-diameter ratio and the soil properties. An empirical equation is suggested to represent the load–displacement relationships of single piles embedded in sandy soil under uplift loading. When the net uplift load per pile in a group is equal to a single pile load, the upward displacement increased in the pile group due to interaction effects between piles. The obtained group efficiency under uplift loading is illustrated and found to be in a good agreement with previous studies. The uplift group efficiency of a closely spaced pile group decreased with an increase in the number of piles in the group. The group efficiency under uplift loading improved slightly with an increase in the relative density of soil, whereas it decreased with an increase in the pile embedment depth-to-diameter ratio. It is believed that the experimental results presented in this study would be beneficial to the professional understanding of the soil–pile-uplift interaction problem.

Effect of Compressive Load on Uplift Capacity of Cast-Insitu Bored Piles

Field tests were conducted to study the effect of compressive loading on the uplift capacity of single piles embedded in silty sand. The test program consists of four instrumented cast in situ axial pile load tests in compression, pure tension and tension with 25 and 50% of compressive load of ultimate capacity in compression. The experimental results indicate that the net ultimate uplift capacity of single pile decreases with increase in compressive load. The shaft friction is non linear in nature. It observed that as the compressive load increases the shaft friction along the length of pile decreases.

Effect of Arching on Uplift Capacity of Single Piles

An analytical method has been proposed to predict the ultimate uplift capacity of single vertical piles embedded in sand considering arching effect. The present analysis takes into consideration of various pile and soil parameters such as length (L), diameter (d) of the pile, angle of internal friction of soil (ϕ), soil pile friction angle (δ) and unit weight of soil (γ). A modified value of coefficient of lateral earth pressure in uplift has been developed considering the arching effect of soil. A comparative assessment of the uplift capacity of piles predicted by using proposed theory and the existing available theories is made with the existing field and model test results. It has been observed that the present model considering the arching effect predicts the results closer.

Uplift capacity of single piles: predictions and performance

The paper pertains to the development of a simple semi-empirical model for predicting the uplift capacity of piles embedded in sand. Various pile and soil parameters such as length (L), diameter (d) of the pile and angle of friction (ϕ), soil–pile friction angle (δ) and unit weight (γ) of the soil which have direct influence on the uplift capacity of the pile are incorporated in the analysis. A comparative assessment of the ultimate uplift capacity of piles predicted by using the proposed theory and some of the available theories are made with respect to each other and with reference to the measured values obtained from model tests in the laboratory. For this purpose experimental data have been collected from the literature and also from model tests conducted as a part of the present investigation. The study shows the proposed model has an excellent potential in predicting the uplift capacity of piles embedded in sand that are consistent with model pile test results.