Lateral Resistance of a Single Pile Embedded in Sand with Cavities

The research presents an experimental study of the interaction between cavity and adjacent pile in sandy soil. Experimental studies were performed to investigate the effects of the different factors (such as cavity locations, batter angle of pile, pulling height and vertical dead loads) on the lateral movements, rotations, and ultimate lateral resistance of the pile for three states of soil (dry, water at rest and water flowing laterally). The analysis of the experimental results of the dry models indicate that the model tests for very deep or shallow cavity with negative distance ratio( the horizontal distance from the centerline of the pile to the centerline of the cavity, S/B=-8) carries more load than the cavity case with positive distance ratio. Different failure modes can be observed for each model tests depending upon the geometry of the problem. The resistance of the batter pile are generally smaller than that of the vertical pile case for cavity with ( depth of the cavity to length of the pile, D/L=1 and S/B=0). Also for the same cavity location, the effects of lateral load position on batter pile are very low. The pile with vertical dead load of (228.6 N) carries more lateral load than pile with no vertical load for the same cavity condition. This behavior is reversed for soil without cavity. In spite of that the constant lateral load is greater than the ultimate lateral resistance of the case (F.S=0.8) during the observations of the lateral displacement with time, failure does not occur for cavity condition with (D/L=0.5 and S/B=-8). The results of the model tests with the presence of the water show the methodology of the water flowing in the lateral load direction is more dangerous on the pile stability than water at rest state for no cavity condition, but the water at rest becomes very dangerous state for any cavity condition

Effect of Stress Level of Surrounding Soil on Bored Pile Capacity in Sand

This study deals with assessing the effect of stress level on bearing capacity factor , distribution of shear stresses at soil-pile interface along pile shaft, and presence of critical depth concept for bored piles axially loaded in compression and embedded in dense sand. These investigations are made using finite element method with the employment of a wide range of stresses by using piles with dimensions starting from laboratory dimensions and goes towards field dimensions with embedment ratio range from (15-40). The soil and the interface behavior is modeled using Duncan-Chang hyperbolic soil model with empirical equations account for reduction of angle of internal friction ø with increasing in stress level. Bored pile is modeled as a linear elastic material. The results showed a dramatic decrease in bearing capacity factor as length of pile increase. It was also found that the embedment ratio has a significant effect in increasing bearing capacity factor , and the distribution of shear stresses at soil-pile interface is not linear and does not tend to take a constant value beyond a certain depth of pile nor decreases after a certain depth along pile shaft. The fallacy of critical depth also noticed and discussed in this paper

Effect of Pore Water Pressure Parameters on The Stability of AL-Ad'daim Earth Dam

The construction and operation of earth dams (homogeneous and those of clay cores) arenormally controlled by the pore water pressure generated during these stages. These pore waterpressures are the main reason behind the dam deformations, settlements, and instability.Throughout the experimental part of the study, a large number of classification tests, physicaltests, and B -stress path tests were carried out. In the theoretical part of the study, the finiteelement analysis was adopted to assess the effect of the pore water pressure parameters of themarl (dam core) and the water contents of the compacted core layers on the expecteddeformations and stability of an earth dam throughout the construction and operation stage

Effect of Stress Level on Behavior of Bored Piles Embedded in Medium Sandy Soil

In this paper investigation in the end bearing and shaft resistance of bored piles embedded in medium sand and subjected to axial load for wide rang of stress levels starting from laboratory dimensions and go toward field dimensions were made by utilizing the finite element method. The soil is modeled using hyperbolic soil model with empirical equation account for reduction of angle of internal friction Ø with increase in stress level while the bored pile assumed as a linear elastic material. It was found that the stress level has a significant effect on pile’s behavior and the small scale model in laboratory dimension not represent the real behavior of pile in field dimensions and if the results from such dimensions are adopted, it will lead to overestimate of bearing capacity factor Nq. Also, the effect of embedment ratio (L/D) on pile’s behavior is examined in this study and the results showed that the embedment ratio (L/D) increases the bearing capacity factor Nq up to a certain length beyond it the effect of embedment ratio (L/D) diminished

Effect of Reduced Zone on Time-Dependent Analysis of Tunnels

The problem of the proposed “Baghdad metro line” which consists of two routes of 32 km long and 36 stations is analyzed. The tunnel is circular in cross-section with a 5.9 m outer diameter. The finite element analyses were carried out using elastic-plastic and modified Cam clay models for the soil. The excavation has been used together with transient effects through a fully coupled Biot formulation. All these models and the excavation technique together with Biot consolidation are implemented into finite-element computer program named “Modf-CRISP” developed for the purpose of these analyses. The results indicate that there is an inward movement at the crown and this movement is restricted to four and half tunnel diameters. A limited movement can be noticed at spring line which reaches 0.05% of tunnel diameter, while there is a heave at the region below the invert, which reaches its maximum value of about 0.14% of the diameter and is also restricted to a region extending to 1.5 diameters. The effect of using reduced 0 zone on excess pore water pressure and surface settlement (vertical and horizontal) was also considered and it was found that the excess pore water pressure increases while the settlement trough becomes deeper and narrower using reduced 0