• Geomechanics and Engineering
• /
• v.16 no.3
• /
• pp.309-320
• /
• 2018

In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.

• Geomechanics and Engineering
• /
• v.32 no.4
• /
• pp.453-462
• /
• 2023

Designing pile foundations subjected to the uplift forces such as buildings, oil platforms, and anchors is becoming increasingly concerned. In this paper, the conceptual design of a new type of driven piles called expanding pile is presented and assessed. Some grooves have been created in the shaft of the novel pile, and some moveable arms have been designed at the pile tip. At first, static analyses using the finite element method were performed to evaluate the effectiveness of the innovative pile on the axial bearing capacity. Then its effect on seismic behavior of moment frame is considered. Results show that the expanding arms were provided an ideal anchorage system because of the soil's noticeable locking-up effect increasing uplift bearing capacity. For example at the end of the static tensile loading procedure, displacement decrement up to 55 percent is observed. In addition, comparing the uplift bearing capacity of the usual and new pile with different lengths in sand and clay layers shows noticeable effect and sharp increase up to about two times especially in longer piles. Besides, a sensible reduction in the seismic response and the stresses in the beam-column connection between 23-36 percent are achieved that ensures better seismic behavior of the structures.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.41 no.1
• /
• pp.1-11
• /
• 2021

In order to reuse existing onshore turbine foundations, it is important to redesign and reinforce the existing foundations according to the upgraded tower diameter and turbine load. In the present study, a slab extension reinforcement method and structure details of an anchorage part were examined in consideration of the reuse of spread footings, which are the most widely used foundation type in onshore wind turbine foundations. Experiments were conducted to evaluate the load resistance performance of a reinforced spread footing according to structure details of an anchorage part. The results showed that (1) the strength of an anchorage part could be increased by more than 30 % by adding reinforcement bars in the anchorage part, (2) pile-sleeves attached to an anchor ring contributed to an increase in rotational stiffness by preventing shear slip behavior between the anchor ring and the concrete, and (3) slab connectors contributed to an increase in the strength and deformation capacity by preventing the separation of new and old concrete slabs.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.12
• /
• pp.107-113
• /
• 2017

Shear Connector should be used to fix the PHC pile with extension wall in order to utilize PHC-W retaining wall as permanent wall. The pullout behaviours on shear connectors anchored into PHC-W pile were observed as two modes. The first type behaviour showed that after reaching the maximum pullout resistance, the anchorage was broken and shear connector was pulled out abruptly. The second type behaviour showed that even after arriving the maximum pullout resistance, the anchorage was not destroyed and there was a progressive increase in pullout displacement. The maximum pullout resistance of the steel anchor shear connector is larger than that of deformed bar shear connector. The larger the diameter and the longer the embedment length of shear connector, the higher the maximum pullout resistance would be. The pullout displacements corresponding to the maximum pullout resistance of the shear connector showed various ranges regardless of the materials, the diameters and the anchoring lengths. A-D20 shear connectors showed a pull-out displacement of about 8~10 mm. A-D16, D-D19 and D-D16 shear connectors exhibited a pulling displacement of about 14~20 mm, but a pulling displacement of about 6~10 mm when the anchoring lengths were 50 and 80 mm.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.42 no.6
• /
• pp.825-836
• /
• 2022

Micropiles can be used to support additional load in extended building structures. However, their use brings about a risk of exceeding the bearing capacity of existing piles. In this study, pre-compression was applied to distribute the load of an existing building to micropiles, and an indoor loading test was performed to confirm the structural applicability of a wedge-type anchorage device designed to improve its capacity. According to the test results, the maximum strain of the anchorage device was 0.63 times that of the yield strain, and the amount of slip generated at the time of anchorage was 0.11 mm, satisfying structural standards. In addition, using MIDAS GTS, a geotechnical finite element analysis software, the effect of the size of the pre-compression, the thickness of the soil layer, and the ground conditions around the tip on the reaction force of the existing piles and micropiles were analyzed. From the numerical analysis, as the size of the pre-compression load increased, the reaction force of the existing pile decreased, resulting in a reduction rate of up to 36 %. In addition, as the soil layer increased by 5 m, the reduction rate decreased by 4 %, and when the ground condition at the tip of the micropile was weathered rock, the reduction rate increased by 14 % compared with that of weathered soil.