Kamran Panaghi

The ever-expanding urban architecture in developing areas requires more land space for construction purposes to be available. For this, utilizing the sub-surface areas through excavations in populous cities is now on the increasing trend. Two major concerns in such excavation projects are excavation-wall stability and the induced ground settlements which can be countered by a soil nailing-ground anchor system. In this regard, influential factors such as nail length and nail inclination angles can affect the overall performance of stabilized ground. Therefore, the focus of the present study is on how the aforementioned influence excavation-induced ground deformations. The numerical simulation is conducted using the software Plaxis 2D. The established numerical models help to explain how changes in the nails’ inclination angles and anchor lengths can change the observed behavior of the walls; from which helpful tips for practicing engineers are drawn accordingly. Such results could also be utilized for classroom presentations to aid students’ understanding of geotechnical engineering concepts.

This study presents the results of modeling the soil-pile interaction phenomenon under acceleration-time history seismic loading. The studies are carried out for three sets of single piles with different diameters which consider the effect of gapping between soil and pile in more details. The Drucker-Prager soil constitutive law is used to model soil behavior while the behavior of the concrete piles is assumed to be elastic. Analyses were conducted by the commercial program ABAQUS 6.8 and the results were converted to the corresponding frequency magnitudes that are of more interest for the frequency dependent transfer and impedance functions regarding the kinematic and inertial interactions, respectively. The results showed that the effect of gapping on the kinematic interaction is to increase the displacement of the pile head compared to free-field. In addition, gapping causes reduction in the stiffness and damping of the system in general.

This work tried to focus on the effect of the constitutive law considered for soil on the functions that can be interpreted as means by which soil-structure interaction is studied. Groups of 2 x 2 and 3 x 2 piles were considered in analyses within which two types of soil behavioral laws were used. The finite element commercial program ABAQUS was used for modeling the whole system. The effects of far-field were imposed on the models boundaries by the infinite elements applicable to the sides of every system. Earthquake excitation with a low predominant frequency within its highest amplitudes was applied to the bedrock. This acceleration-time history had duration of 10 seconds. The two types of soil constitutive laws included simple plastic and Drucker-Prager models. It was found that Drucker-Prager soil constitutive law estimated the results of both kinematic and inertial interaction higher than the simple plastic model.