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The pile-raft foundation is a combination of a raft foundation with piles. Pile-raft foundation has been widely designed, assuming all structure loads to be transferred to piles without considering contribution of the load taken by contact surface between raft and soil. Methods of analysis currently used in practice are based upon relatively conservative assumptions of soil behavior or on the less realistic soil-structure interaction. In this study the bearing -settlement behavior of combined pile-raft foundations on medium dense sand was investigated. 1g physical model test was performed on a circular rigid raft underpinned with four model piles. Numerical simulation was also carried out on the model test, using FLAC-3D, to show compatibility of the numerical analysis with the test. The obtained results showed very good accuracy of the numerical method used in this study as long as the applied load does not exceed the working load, while the performance of numerical model was relatively good for the loads beyond working load.

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The concept of Geosynthetic Cellular Systems (GCS) has recently emerged as a new method in construction of breakwaters and coastal protective structures. The method potentially has significant advantages compared to conventional systems from the standpoint of constructability, cost effectiveness, and environmental considerations. This paper presents the results of physical model testing on the hydraulic responses of GCS structures under wave action. A series of model tests were carried out in a wave flume on GCS models with different shapes and soil types, subjected to various wave characteristics. Horizontal wave forces acting on the models were measured at different elevations. The maximum horizontal force in each test was calculated and compared with conventional formula of predicting wave pressure on breakwaters. The results show that Goda’s equation overestimates the hydrodynamic water pressure on these structures. This can be attributed to the influence of seeping water through the GCS models because of relative permeability of the GCS.

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Physical modeling for study of deep foundations can be performed in simple chambers (1g), calibration chambers (CC),

and centrifuge apparatus (ng). These common apparatus face certain limitations and difficulties. Recently, Frustum Confining

Vessels (FCV) have been evolved for physical modeling of deep foundations and penetrometers. Shaped as the frustum of a

cone, this device applies steady pressure on its bottom and creates a linear stress distribution along its vertical central core.

This paper presents the key findings in FCV, as developed in AUT. The FCV has a height of 1200 mm, with top and bottom

diameters of 300 and 1300 mm, respectively. By applying bottom pressure up to 600 kPa, the in-situ overburden stress

conditions, equivalent up to 40 m soil deposits, become consistent with the embedment depth of commonly used piles.

Observations indicated that a linear trend of stress distribution exists, and this device can create overburden stress in the

desired control volume along the central core. Moreover, a couple of compressive and tensile load tests were performed on

steel model piles driven in sand with a length of 750 mm, and different length to diameter (L/D) ratios between 8-15.

Comparison between measured and predicted ultimate capacity of model piles performed in FCV demonstrate a suitable

conformity for similar confinement conditions in the field. Therefore, the FCV can be considered as an appropriate approach

for the investigation of piling geotechnical behavior, and the examination of construction effects.

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To dissipate energy and invert excessive discharge flow away from high dams into plunge pool, flip buckets are commonly designed and optimized by hydraulic model studies. In the present study, performance of chute flip buckets in different hydraulic and geometry conditions was investigated using experimental data of five different physical models. The collected experimental data such as Froude number, radius of flip bucket and slope of chute covered a wide range of chute flip buckets in prototype. By analyzing the data, relations for dynamic values of maximum and minimum pressures and their location along the flip bucket were extracted. Moreover, pressure distribution along the central axis of flip bucket was defined. Finally, results of the present research were compared with that of the other researches. Results of this study could be used in the design of chute flip buckets in hydraulic engineering.

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Stilling basins dissipate energy in order to form hydraulic jumps and rotational flows. Hydraulic jump and rotational current phenomenon produces pressure fluctuation at the bottom of stilling basins. In the present study, pressure fluctuations and their locations have been studied in a physical model of Nimrod Dam. Results showed that fluctuations in presence of jump in the basin are high and therefore the fluctuation factors are respectively high. Regarding available empirical equations, the thickness of slab for different hydraulic conditions were calculated and compared in 1D and 2D conditions. By analyzing collected data, it was observed that, results of 1D were underestimated in comparison by 2D calculations.

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The cavitation erosion induced by high flow velocities is very prominent in high head and large unit discharge tunnel. Air entrainment is an effective technology to solve this problem. In this study, numerical simulation and physical model test are applied to the comparative study of air-water flows on bottom and lateral aerator in tunnel. The flow pattern, aeration cavity, air concentration and pressure distribution were obtained and there is a close agreement between the numerical and physical model values. The hydraulic characteristic and aeration effect of anti-arc section are analyzed. The results indicated that added lateral aeration facilities on 1# and 2# aerator can weaken backwater and increase the length of the bottom cavity, but it is limited to improve the air concentration and protect sidewall downstream of the ogee section. Air concentration improved on side walls downstream of anti-arc section when added lateral aeration facility on 3# aerator. The black water triangle zone disappeared and the floor and side walls well protected.