Lateral Pile Capacity Research Articles

Ultimate lateral capacity of single piles in cohesionless soils

Ultimate lateral capacity of single piles in cohesionless soils

Estimation of lateral capacity of rock socketed piles in layered soil-rock profile

Large diameter rock socketed piles were preferred for the purpose of transmission of a huge volume of both vertical and lateral load from superstructure to a deeper depth safely without any structural defects. A series of experimental program was conducted on model pile for studying the behaviour of the rock socketed pile under static lateral load in a soil-rock layered profile system. The model piles were instrumented with displacement and force transducers for measuring the magnitude of the pile movement and load transferred by the pile. The experimental results showed that the rock socketed pile lateral capacity has significantly affected by the depth of embedment of the pile in soil and depth of rock socket. There was a considerable increase in the lateral capacity of the pile when the depth of socketing is three times the diameter of the pile into rock with a minimum embedment. In the 3D socketed piles, the lateral capacity of the pile is almost 18 times higher than the non-socketed piles. From the experimental study, it is also observed that when the piles socketed more in to the hard strata (rock), the depth of fixity increases and the lateral displacement reduces substantially.

Static and dynamic lateral non-linear pile–soil–pile interaction

Three-dimensional finite-element analyses are performed to compute the interaction factors between two neighbouring piles, under both static and dynamic horizontal displacements. The fixed-head elastic piles are flexible, embedded in a homogeneous saturated clay stratum, and loaded under undrained conditions. Soil inelasticity and soil–pile interface separation are modelled in a rational way. With the aim of improving fundamental understanding of pile–soil–pile non-linear interaction mechanisms, it is found that the effect of a loaded (‘source’) pile on an adjacent (‘receiver’) pile diminishes rapidly with increasing amplitude of imposed displacement, at a rate which depends on the angle of departure from the direction of loading between source and receiver piles. Gap formation at the back of a displaced pile affects the response of the group. Using the interaction factors developed, the behaviour of 2 × 2 and 3 × 3 pile groups is analysed and compared with the three-dimensional analysis of the whole group. Under static conditions the differences between front (‘leading’) and back (‘trailing’) piles are illustrated. Under cyclic dynamic conditions, the separation gap forms on each side of a pile alternately, leading to the peaks in stiffness diminishing, and leading to larger (than the elastic) group efficiencies. Superposition using proper non-linear interaction factors offers reasonable approximation, but only for moderate amplitudes of load, smaller than about one-half of the ultimate lateral pile capacity.

Responses of single and group piles within MSE walls under static and cyclic lateral loads

To investigate the behavior of piles and the performance of the mechanically stabilized earth (MSE) walls under static and cyclic lateral loading, six reduced-scale model tests of single and group piles within the MSE walls were conducted inside a test box. In the single pile tests, a hollow aluminum tube as a pile was placed at a distance of 2D or 4D (D is pile diameter) behind the wall facing, while in the group pile tests, the piles were only placed at the distance of 2D with a spacing of 3.3D between the piles. The piles were subjected to static lateral loading only and cyclic lateral loading followed by static loading until failure. The test results showed that the lateral load capacity of each pile in the group pile test was approximately 60% that of the single pile, while the wall facing displacements and the geogrid strains in the group pile test were larger than those in the single pile test. The lateral pile capacity, the wall facing displacement, the strain in the geogrid, and the lateral earth pressure behind the wall facing in the static and cyclic loading tests were evaluated at the pile head displacement equal to 20%D.

Three-dimensional numerical analysis of under-reamed pile in clay under lateral loading

Unlike the bearing and uplift capacities of under-reamed pile, the lateral resistance of under-reamed pile is studied by a very few researchers. Therefore, in the present study, a three-dimensional numerical analysis is carried out to study the response of under-reamed pile in clay under lateral loading. In the numerical analysis, various parameters such as embedment length to shaft diameter ratio (Lu/D), top bulb distance from the base to bulb diameter ratio (hb/Du), undrained cohesion (cu), rate of increase of undrained cohesion (m), number of bulbs, and bulb spacing to bulb diameter ratio (s/Du) are considered as variables. From the present study, load–deflection curve, variations of deflection, shear force, and bending moment, displacement contour, and soil stress in front of the pile are obtained. The lateral load-carrying capacity of under-reamed pile is estimated based on displacement-based criteria. The lateral load-carrying capacity of under-reamed pile (Qhur) is found to increase with increase in Lu/D, hb/Du, number of bulbs, cu, m, and decrease in s/Du. The deflection at the pile head is found to decrease significantly with increase in hb/Du and number of bulbs, and decrease in s/Du. It is expected that the present results will be useful from serviceability point of view.

Experimental Investigation of the Uplift and Lateral Bearing Capacity of Root Piles

The root pile, a new type of pile foundation with a variable cross-section, is introduced. The mechanism of root piles under uplift and lateral loading and the construction process are presented and discussed. The bearing capacity of root piles under uplift loading, lateral loading, and combined uplift and lateral loading was compared with that of conventional straight piles through field loading tests, which were performed on two straight piles and two root piles. The results indicate that the uplift and lateral bearing capacity of root piles is significantly greater than that of straight piles; the combined uplift and lateral loading has almost no influence on the uplift bearing capacity of single piles, but would weaken their lateral bearing capacity; the roots are engaged gradually from the top to the bottom under uplift loading; the resistance of the roots increased substantially because of the interaction between the soil and roots; however, the side friction of the pile shaft above the roots decreased because of this interaction. Increasing the burial depth of the roots could improve the performance of the roots for building applications.

An analysis method for lateral capacity of pile foundation under existing vertical loads

In practical engineering, the pile foundation is often subjected to lateral load while bearing vertical load. And the lateral and vertical bearing capacity of pile generally are calculated separately during the design of pile, without considering the effect of existing vertical load on the lateral capacity of pile. Based on the theory of elastic foundation beam, the stress in the pile units of laterally loaded pile under existing vertical load are analyzed, the pile-soil friction effect, p-Δ effect and the effect of existing vertical load on soil resistance are considered comprehensively. The p-y curve formula of sand considering the effect of existing vertical load is introduced, and the theoretical calculation model of lateral capacity of pile under existing vertical load is established. The corresponding program is compiled through MATLAB software. The mechanical response of pile is obtained, and the effects of different existing vertical loads on the lateral capacity of pile are compared. By comparing the theoretical calculation result with the experimental result, the applicability of the proposed method is verified.

Effect of the proximity of slope and pile shape on lateral capacity of piles in clay slopes

The response of laterally loaded piles installed near the crest of clay slopes is analysed. Three-dimensional finite element analyses are presented for piles at various distances from a slope crest and for different pile shape. The results of these analyses are used to study the variation of the pile displacement, the bending moment of the pile and the soil resistance in relation to pile to slope distance and pile shape. The obtained results show that the proximity of slope significantly affects the lateral load capacity of the piles but not significantly when the piles are placed at 7D (where D is pile diameter) or greater from the slope crest. Furthermore, the lateral soil resistance on the ground surface for circular piles is larger than that for rectangular piles at the same lateral load in level ground. The decrease rate of lateral soil resistance on the ground surface for circular piles gets faster as the slope ratio and load level increase.

Upper-bound analysis of laterally loaded rigid monopiles in clay with linearly increasing strength

Monopiles supporting offshore wind farms are often subject to severe lateral environmental loads due to wind, waves, and currents. Previous studies have reported various failure patterns for such rigid monopiles in clay; hence predicting lateral pile capacity of widely different magnitudes. In this study, both a single-sided wedge failure mechanism involving passive soil failure only and a two-sided wedge failure mechanism with simultaneous active and passive soil failures are proposed. The single wedge mechanism is found to be applicable if the soil behind the pile does not move together with the pile, resulting in a gap between the soil and the pile upon loading. In contrast, the two-sided wedge is found appropriate for the soil behind the pile that moves together with the pile upon loading. Two formulations are then derived from the two upper-bound failure mechanisms. The lateral pile capacity can be determined and the corresponding failure mechanism identified based on the formulation that yields the lower capacity magnitude. In addition, the reliability of the formulations is verified against reported finite element methods as well as existing experimental and field test results.

Effect of Soil Improvement Techniques on Increasing the Lateral Resistance of Single Piles in Soft Clay (Numerical Investigation)

Soft clay soil extends in many areas all over the world. The construction on soft clay is one of the most important problems in engineering practice. When the design engineers face this problem, they always use deep foundations. In many cases, the vertical loads are satisfied but the lateral capacity of the piles is not satisfied. In this paper, a series of 3D finite element analysis was performed to investigate the effect of soil improvement techniques on increasing the lateral pile capacity. The 3D finite element results indicate that the improvement in the lateral pile capacity is strongly dependent on the combined effect of the lateral extent and the thickness of the improved zone around the pile head. The analysis indicates that the lateral pile capacity increased to about 240% greater than the capacity in native soft clay when a portion of soft clay is excavated and replaced with dense sand. In addition, the lateral pile capacity increased to a value greater than 600% when the soft clay is mixed with cement.

A simple approach for predicting the ultimate lateral capacity of a rigid pile in sand

Rigid piles are widely used as foundations to resist lateral load. A calculation to confirm that the ultimate lateral geotechnical capacity of such piles is not exceeded is required for ultimate limit-state design. Existing (empirical) approaches employed to predict the lateral capacity of a rigid pile in sand assume the net soil pressure is a function of the vertical effective stress and friction angle. However, difficulties in determining the appropriate friction angle(s) make these approaches less useful for practical purposes. A simple alternative approach correlated with the cone penetration test end resistance (qc) is developed in this paper based on ultimate capacities measured in a new series of tests on rigid piles with diameters of 127, 169, 273 and 457 mm and aspect ratios (L/D) between 1·6 and 12. These test results are combined with additional tests reported in the literature to establish a simple formulation for the ultimate net pressure adjacent to a pile in sand. Explicit design equations are also presented for soil profiles with a constant qc value and where qc increases linearly with depth. The proposed equations are seen to provide good estimates of capacities for rigid piles with a wide range of diameters.

Effect of Edge Distance on Lateral Capacity of Piles in Cohesionless Soil Slopes

Recent advances in the understanding of deep foundation mechanisms suggest that the pile foundations can be used in both level grounds and the sloping grounds to appropriately support the heavy axial and lateral loads coming from the superstructures. The lateral load-carrying capacity of the pile in the sloping ground is different from the level ground due to the presence of slope and pile location (i.e., edge distance). In this study, extensive numerical analyses were performed to understand the behavior of a laterally loaded pile in cohesionless soil slopes by using the three-dimensional finite element method. Effect of various influencing parameters like slope inclination, relative density, angle of internal friction, modulus of elasticity of soil, unit weight of soil, L/D ratio of a pile, and pile diameter on the laterally loaded pile with a change in edge distance was studied. Results from the numerical analyses were compared with the previous experimental studies. An attempt has also been made to find out critical edge distance (i.e., where the effect of slope angle is negligible on lateral capacity) of the pile for different cohesionless soils with varying slope configurations. The critical edge distance is found to be varying between 5.0–7.5D, 7.5–10.0D, and 10.0–15.0D with slope inclinations of 20°, 30°, and 40°, respectively.

Theoretical Analysis of Plate Location Effect on Soil Failure State under Horizontal Force of a Concrete Plate-Expanded Pile Used for Oceanographic Engineering

Qian, Y.; Chao, S., and Wang, R., 2020. Theoretical analysis of plate location effect on soil failure state under horizontal force of a concrete plate-expanded pile used for oceanographic engineering. In: Gong, D.; Zhang, M., and Liu, R. (eds.), Advances in Coastal Research: Engineering, Industry, Economy, and Sustainable Development. Journal of Coastal Research, Special Issue No. 106, pp. 655–659. Coconut Creek (Florida), ISSN 0749-0208.In oceanographic engineering, the concrete plate-expanded pile is a new type of energy-saving protective pile. Expanded plate parameters affect the bearing capacity of the horizontal load. In this study, the effect of the plate location, which is an important plate parameter, on the failure state of concrete plate-expanded piles was studied, mainly with the ANSYS finite element analysis software to simulate and analyze models with different plate locations under horizontal action and to determine the effect of plate location on the failure state, which provides a theoretical basis for further research on the design of lateral load-bearing capacity of concrete plate-expanded piles and promotes the development of the design technology of these types of piles.

Failure Modes of Laterally Loaded Piles Under Combined Horizontal Load and Moment Considering Overburden Stress Factors

A large number of studies on various aspects of laterally loaded piles in clay have been conducted in the literature based on experimental and numerical analyses; however, the lack of studies on the influence of the soil unit weight on the undrained capacity of the problem is obvious. In this paper, the effects of the overburden stress factors on the undrained capacity of laterally loaded piles under combined horizontal load and moment are comprehensively investigated by employing the three-dimensional (3D) finite element analysis. In the present study, soil–pile interfaces are modelled as the no-tension condition while the influences of the pile length ratios are also examined in the numerical analyses. The failure envelopes of laterally loaded piles under combined horizontal load and moment incorporating overburden stress factors, pile length ratios are presented. Employing the normality rule to the derived failure envelopes, the failure mechanisms corresponding to the ratio between applied moment and horizontal load are postulated in this paper. An approximate solution of the failure envelope of laterally loaded piles is also proposed by using a nonlinear regression analysis, and provides a convenient tool for predicting the undrained lateral capacity of piles considering overburden stress factors in practice.

Study on Lateral Bearing Capacity of Cantilever Rigid Piles under Large Horizontal Displacement

In order to analyze the lateral ultimate bearing capacity of cantilever rigid pile with large horizontal displacement, this paper studies the distribution characteristics of soil resistance on the side of pile and the calculation method of lateral bearing capacity of pile foundation by means of numerical simulation and theory. The results show that under the condition of large displacement, the soil in front of the pile is yielded layer by layer from top to bottom, and when the soil layer on the side of the pile reaches the limit displacement, the soil resistance on the side of the pile no longer increases with the increase of displacement. The lateral ultimate bearing capacity of cantilever rigid pile under large horizontal displacement is fitted and calculated by using the ultimate displacement of pile side soil, in which the fitting effect of modified “m” method is the best, and the applicable range of foundation coefficient distribution needs to be further studied.

Study on Effect of Ground Improvement on Lateral Load Carrying Capacity of Pile using Developed Simplified Soil–Pile Stiffness Matrix

In this present study, a Beam on Nonlinear Winkler Foundation approach has been utilized to study the effect of ground improvement on deformation characteristics of laterally loaded pile. Fourth-order governing differential equation of pile deformation has been solved, and a simplified pile–soil stiffness matrix has been developed. The optimum depth (from ground surface) up to which engineering properties of soil require to be improved has been ascertained using a computer code developed in MATLAB utilizing the developed soil–pile stiffness matrix. This optimum depth can be defined as the depth beyond which the improvement in engineering properties of soil (e.g., deformation modulus) has negligible effect on deformation characteristics of laterally loaded pile. Optimum depth has been suggested for different slenderness ratios of piles installed in soft-to-medium-stiff clayey soil deposit, and statistical equations have been developed to find the optimum depth of ground improvement for different pile slenderness ratios (L/D) and relative stiffness (Ep/Es) of pile. The study reveals that the optimum layer improvement ratio (L1/L) reduces with the increased pile slenderness ratio (L/D) and increases with the increased relative stiffness (Ep/Es) of pile. Design charts have been proposed to get a preliminary estimation of lateral pile capacity in virgin clay as well as improved clay for different layer improvement ratios (L1/L).

Model study on the performance of single-finned piles in clay under lateral load

Generally, foundations of many structures, such as transmission towers, bridge abutments, ocean engineering structures, marine dolphins, dock-fendering systems, and moorings are subjected to different modes of lateral loading. This research aims to study an alternative and novel technique to improve the lateral pile capacity in clay using fins at the top of piles. Laboratory small-scale model tests were carried out to study the behavior of laterally loaded finned piles installed in clay soil for different undrained shear strengths (Cu = 11 and 15 kPa). The effects of different factors, such as pile type, stiffness, geometric dimensions, and shapes of fins, were studied. Moreover, the effects of the fin number and inclination angle were also investigated. Results emphasized that there is an increase in the lateral pile resistance against the lateral load after placing fins at the top of the pile head. It has been found that the optimum length of the adopted fins should equal 0.4 of the pile embedded length and the fin width should equal the pile diameter. The existence of fins improved the behavior of finned piles by 1.67 and 1.55 for piles of L/D = 10 in the case ofCu = 11 and 15 kPa, respectively, compared to regular normal piles in the same condition. Also, the improvement in L/D = 22 piles due to fins reached to 1.29 and 1.35 for the case of Cu = 11 and 15 kPa, respectively.

Laboratory Study of Lateral Load Capacity and Behaviour of Short Piles in Clayey Soil.

This research is an experimental study investigating the lateral loading capacity of piles in clayey soil. Important factors considered in this study included pile diameter, embedded length of pile, effective unit weight, and degree of saturation of soil, which were studied for their effects on the lateral loading capacity of short driven piles. The experimental study involved testing six specimens in the laboratory, each made of galvanized iron of 21.7 and 27 mm diameter and L/d (embedded length/diameter) ratios of 10, 14, and 18. The specimens were subjected to lateral loadings while embedded in clayey soil with effective unit weights of 13, 15, and 15.6 kN/m3 and degrees of saturation of 30, 41 and 97%, to simulate true pile behaviour. The obtained pile responses were then plotted as force-displacement diagrams. The varying parameters were thus diameter and embedded depth of pile, effective unit weight, and degree of soil saturation. The results of this experimental study on the behaviours of the piles under the influence of lateral loading in the clay were also compared with the predicted lateral capacity of the piles based on work by other researchers. Moisture content and degree of saturation were found to have the greatest effects on pile behaviour. This study thus aids understanding of the behaviours of short piles embedded in clayey soil under lateral loading to allow designers to take practical steps and choose an appropriate method when designing a pile.

Vertical and Lateral Bearing Capacity of FRP Composite Sheet Piles in Soft Soil

Fiber‐reinforced polymer (FRP) composite sheet piles are usually favored for slope and river‐retaining structures due to their construction and environmental efficiency. Their applications, however, have been hindered by the lack of understanding of the bearing capacity. This paper studies the vertical and lateral bearing capacity of FRP composite sheet piles through three full‐scale tests conducted in Haiyan, a soft soil site in the Yangtze River Delta of China. In the three tests, we measured the vertical bearing capacity of the FRP composite sheet piles, the bearing capacity of the composite foundation, and the lateral capacity of the FRP composite sheet piles, respectively. The test results show that the Q‐S (load on the top of the pile versus settlement) curve of the FRP composite sheet piles exhibits a steep fall while that of the composite foundation is relatively flat. Moreover, the ultimate bearing capacity of the FRP composite sheet piles is measured to reach 23.8 kN while that of the composite foundation increases by 47.1 %, reaching 35.0 kN. It shows that the FRP composite sheet piles under the composite foundation have a favorable bearing performance. Finally, the final horizontal displacement of the FRP composite sheet pile in the reinforced area with anchoring the sheet pile is smaller than the final horizontal displacement in the nonreinforced area, indicating that the horizontal bearing capacity can be significantly improved by anchoring the sheet pile.

The Effect of Vertical Loads and the Pile Shape on Pile Group Response under Lateral Two-Way Cyclic Loading

This paper is presented the lateral dynamic response of pile groups embedded in dry sand under influence of vertical loads and the pile shape in-group, which are subjected to the lateral two-way cyclic loads. The laboratory typical tests with pile groups (2×1) have an aluminum-pipe (i.e. circular, square) pile, embedded length to diameter of pile ratio (L/D=40) and spacing to diameter ratio (S/D) of 3, 5, 7 and 9 are used with different cyclic-load ratio (CLR) 0.4, 0.6 and 0.8. The experimental results are revealed that both the vertical and lateral pile capacity and displacement is significantly affected by the cyclic-loading factors i.e. (number of cycles, cyclic load ratio, and shape of pile) .In this study, important design references are presented. Which are explained that the response of the pile groups under cyclic lateral loading are clear affected by the attendance of vertical load and pile shape. Where, it is reduction the lateral displacement of group piles head and increase lateral capacity about (50) % compared without vertical loads. On the other side, the pile shape is a well affected to the pile response where the level of decline in lateral displacement at the pile groups head in the square pile is more than circular pile about 20 % at the same load intensity.