Numerical assessment of axial pile group response based on load test

Pile foundation analysis and design using experimental data and 3-D numerical analysis

“…According to Fleming et al [23], Poulos and Davis [6], and Kitiyodom and Matsumoto [24], the overestimation may be very significant when the reaction piles are close to the test pile. As pointed out by Comodromos et al [15], the effect is due to the earlier mobilization of the shear strength of the soil between the pile under test and the reaction piles. Eventually, a simultaneous downward movement of the tested pile and upward of the reaction pile produces a higher level of shear strain, and, as a result, shear strength mobilization is developed earlier than in the corresponding case of single pile.…”

“…Using 3-D nonlinear analysis Comodromos [14] demonstrated that, in the case of pile groups with fixed head conditions (no contribution of the raft), the group bearing capacity efficiency factor, defined as the ratio of the ultimate bearing capacity of a pile group to that of the single pile multiplied by the number of piles, did not deviate significantly from unity. Comodromos et al [15] came to the same conclusion when examining free-head pile groups in which each pile was loaded with the same load. In contrast, it was found that the interaction affects the group stiffness efficiency factor considerably.…”

“…This value represents also the increase in stiffness due to the presence of the reaction piles. It should be noted that the effect is valid for the initial loading part of the curve (linear-elastic part) and that the effect becomes less important as yielding of the surrounding soil occurs [15]. In the back-analysis of the pile test, mentioned below, this assumption is addressed.…”

Response evaluation of axially loaded fixed‐head pile groups in clayey soils

“…The proposed method has also been used in the case of clay profiles with shear strength and Young's modulus increasing with depth as described in paragraph 4. Figure 17 illustrates the load-settlement curves calculated using FLAC 3D (continuous lines), while dashed lines with the same markers stand for predicted curves using the proposed relationship and the above values for the parameters A, B, C and E in the case of a 3×3 layout with a spacing of 3.0D, a relative length L/D = 25 and shear strength and Young's modulus given by Equations (10) and (11). The stiffness mean error K m err and the potential energy error W err for the above case are equal to 6.7 and 5.9%, respectively.…”

Study About the Effects of Pile Spacing on the Performance of Pile Group Under Composite Loads, Adjacent Structure Loads, and Bending Moment in Sand

“…The lateral resistance of a long flexible pile decreases when the water level changes from horizontal to sloping [6]. The soil lateral pressure in lateral load state varies with the width and depth of the pile, while this depends on the severity of the load and water level [7]. A test for examining the interaction of pile group and its effects, in order to assess their behavior, considering the pile spacing in group under lateral load, was conducted, in which groups of 3x3, 3x4, 3x5 were spaced at 3.3d, 4.4d, 5.65d respectively, and it was concluded that lateral load resistance depends on the spacing of the piles, while, by having this spacing decreased, the reciprocal effect of group gradually gains importance [8].…”