جستجوی مقالات مرتبط با کلیدواژه « مدل عددی » در نشریات گروه « عمران »

The degree of connection rigidity has a significant effect on the seismic behavior of steel frames. However, the lack of proper modeling methods or not considering the degree of rigidity of the connection in the design of structures, destroys the accuracy of the design. In conventional methods for the analysis and design of steel frames, the behavior of beam-to-column connections is assumed to be joint or fully braced. With these assumptions, the analysis and design of steel frames becomes easier. But the results of the tests show the existence of a degree of flexibility in the hypothetical clamp joints and a degree of stiffness in the common joint joints. Therefore, for accurate and economic analysis and design of steel frames, it is necessary to consider the tightness of the connections. Few researches have been done on the nonlinear modeling of steel connections with nonlinear shock absorbers, and most of these studies are also on the modeling of connections using the finite element method. This shows the need to deal with the correct and practical modeling of connections. There are various methods for numerical modeling and calibration of experimental and nonlinear behavior of structures, among them, the modeling method with nonlinear springs, plastic joint models, fiber models, and models can be used. Designing finite elements pointed out. One of the advantages of modeling with non-linear springs and plastic joints is the non-linear modeling of the failure zone with minimal degrees of freedom. In this method, calibrated functions are used to model the nonlinear behavior of the structure. But in the method of fiber models and finite elements, the nonlinear behavior of the structure is determined by assigning the nonlinear behavior of the materials. Disadvantages of the fiber modeling method include the absence of shearing and twisting effects, sliding between components, and cracking and crushing of materials. Finite element modeling also provides the ability of three-dimensional behavior, including complex geometries and multiaxial stress and strain states. In the finite element modeling method, determining the size of the elements requires a convergence test. Also, due to the high volume of calculations and its time-consuming nature, this method is used in detailed models to model a part of the structure. In this paper an accurate estimate of the seismic behavior of these joints and damage modes in them is obtained, using the behavior of valid laboratory samples, to be used as a criterion in numerical modeling. For this purpose, four common steel connections, have been investigated and numerical models are presented to consider the nonlinear behavior of the mentioned connections in the Opensees software. Cyclic behavior of experimental samples has been used to calibrate the characteristics of the proposed numerical model. The results show that with the proposed method, the seismic behavior parameters of the studied connections such as load bearing stiffness and ductility capacity in the experimental and numerical model are well matched and can be used to more accurately model in analyzing and applied designing to obtain an accurate estimate of the behavior of the connections and the degree of rigidity in the designs leading to the operation. It is important to compare the plasticity capacity, maximum bearing capacity and initial stiffness in the examined connections compared to their corresponding numerical models, and the difference between 0.29% and 8.42% in different situations confirms this.

Dams are considered one of the most important infrastructure facilities of a country, which play a very important role in economic prosperity through storage, regulation of water, and also energy production. Due to the volume of water stored in the reservoir of these dams and sometimes their proximity to residential areas, the failure of dams can lead to a lot of human and financial losses, which can be prevented by having sufficient information and proper forecasts of dam failure. The flow resulting from the dam failure is turbulent, mainly a mixture of fluid and sediment particles. Therefore, after the dam's failure, sediment transport leads to significant morphological changes downstream. Based on this, the analysis and evaluation of the instantaneous failure of the dam have been one of the main challenges of the profession of engineers and activists in this field. By examining the research background, it is clear that the studies focused on fluid flow in non-erodible bed conditions, and a small part of numerical and laboratory research has been focused on the evaluation of changes in the morphology of the bed sediment layer. In addition, one of the effective parameters in the mechanism of sediment transfer and the pattern of morphological changes of the bed is the sediments of the dam reservoir, which has received less attention from researchers. Therefore, in this research, we have evaluated and experimental-numerically modeled the phenomenon of sediment transport due to the sudden failure of the dam, taking into account the sediment layer in the dam reservoir.

In this study, two variables (1- the type of sediment particles (fine sand and coarse sand) and 2- the thickness of the sediment layer in the reservoir and downstream of the dam) have been investigated as the main parameters in the evaluation of the sediment transport mechanism (changes in bed morphology). Based on this, scenarios have been defined for laboratory and numerical modeling. In this research, to evaluate the phenomenon of bed sediment transfer based on the phenomenon of instantaneous dam failure, four tests have been defined and implemented in the hydraulic laboratory flume of Babol University in different conditions. This flume is 10 meters long, 50 cm wide, and 50 cm high and is equipped with an ultrasonic level gauge and a digital pressure gauge. In these experiments, two parameters of the type of bed sediment materials (A, B) and also the thickness of the sediment layer downstream of the dam and the reservoir of the dam have been considered as modeling variables. Type A materials are gravel particles with an average diameter of 20 mm, and type B materials are sand particles with an average diameter of 3 mm.

According to the research variables, four scenarios for laboratory modeling and six scenarios for numerical modeling of the phenomenon of sediment transfer based on instantaneous dam failure have been defined. The results of the numerical modeling showed that the numerical model of the research had acceptable accuracy in simulating the phenomenon of sediment transfer due to dam failure, so the modeling error for two-dimensional numerical models (the first four models based on Table 2) is respectively equal to 2.75%, 4.31%, 2.59%, 5.52% compared to laboratory tests.The results showed that in the models of type B sediment materials, the amount of reduction in the thickness of the sediment layer is greater than in the models with type A sediment materials; in other words, the amount of reduction in the thickness of the sediment layer in type B materials is more than type B. The material was A. Therefore, the decrease in the diameter of the sediment particles has caused an increase in the thickness of the sediment layer (bed morphology) due to the failure of the instantaneous dam. In addition, by examining the results obtained from laboratory and numerical models, it was determined that the reservoir sediment layer of the dam is an effective parameter in the rate of sediment transfer and the occurrence of changes in the morphology of the bed based on the dam failure currents, in such a way that with the increase in the thickness of the sediment layer of the reservoir Compared to the downstream sediment layer of the dam, the changes in the thickness of the bed layer have increased by about 10%, as well as the rate of sediment transfer in these conditions.By evaluating the results of dam failure modeling in three-dimensional space, it is clear that the thickness of the sediment layer in the 3D_DB1_NB1 model with type B materials has decreased more compared to the 3D_DB1_NA1 model with type A materials. In addition, according to the contour of the changes in the thickness of the bed layer, it is clear that the type of material of the sediment particles (diameter of the sediment particles) was an effective factor in evaluating the phenomenon of sediment transport in the 3D modeling space. In both 3D models, the thickness of the sediment layer in the area of the dam valve (failure area) has decreased and increased in the range of 1.8 to 2 meters and decreased from 2.2 to 3 meters.

In this research, the main goal is to evaluate the mechanism of sediment transfer due to the sudden failure of the dam, focusing on the effect of the sediment layer in the dam reservoir, which has been implemented in the form of laboratory and numerical modeling. Also, the effect of three parameters, the type of sediment particles and the thickness of the sediment layer in the reservoir and downstream of the dam axis, has been studied.Based on the results of this research and the evaluation and comparisons made between the numerical models and the laboratory model, it is clear that the numerical model created in both two-dimensional and three-dimensional spaces has an acceptable accuracy in simulating the phenomenon of sediment transfer due to dam failure.

The aim of the current research is to evaluate the effect of placing a compound sharp-crested weir at different angles in the channel on its hydraulic performance. For this purpose, Flow-3D software was used to simulate the effect of the placement angle of the compound sharp-crested weir in the channel, considering four angles: zero (perpendicular to the flow pass), 15, 30, and 45 degrees. The comparison of the error percentage obtained between the results of the flow discharge and the depth of the upstream weir from the numerical results and the laboratory data was 0.39% and 2.86%, respectively. The results of the flow pattern passing through the compound sharp-crested weir showed that the flow lines are closer to each other when approaching the crest of the weir at the narrowing place, and the accumulation of flow lines increases in the place of the flow narrowing. The interference of flow lines at the narrowing place reduces the flow coefficient of the flow passing over the weir. The increase in transverse constricting and the decrease of 25 and 50% in the length of the weir crest caused a decrease in the flow discharge coefficient of 14.4 and 9.81%, respectively, compared to the sharp-crested weir of the same channel width. By creating a constant for the weir crown in the width of the compound weirs and placing them at a maximum angle of 45 degrees, the flow rate coefficient is increased 8.91% compared to the angle of the compound sharp-crested weir to the flow.

Stepped spillways are a common structure for energy dissipation by creating frictional resistance to flow through the steps. Based on the studies and depending on flow conditions, the flow over a stepped spillway is usually categorized into three regimes: nappe, transition, and skimming. The stepped spillway is often designed for skimming flows. There were different studies investigating various aspects of stepped spillways, but what is important in this type of spillway is increasing the effectiveness of steps in the rate of energy dissipation. This can be done by a new type of step structure (i.e., inclination angles on steps or using a sill on the edge of a step and cases like that) or geometric alteration and change of steps called labyrinth stepped spillways. Therefore, it is scientifically beneficial to modify the shape of the step of the stepped spillway to increase its collision and roll to achieve energy dissipation. The present study deals with the design of step modification by creating cubic elements on the steps in different arrangements and different hydraulic conditions. This has been considered to improve the performance of stepped spillways by increasing the energy dissipation. For this purpose, using FLOW-3D software, the influence of geometric appendance elements on the steps on the velocity distribution, pressure, the turbulent kinetic energy (TKE), and finally the flow resistance and the energy dissipation on modified spillways was investigated and compared with the flat stepped spillway. The physical model for verifying the numerical results was carried out in a rectangular flume with a length of 12 m, a width of 1.2 m, and a height of 0.8 m. The experiments were conducted on a stepped spillway with a slope of 26.60° and consisted of 10 steps with step length (l) and height (h) of 0.06 and 0.12 m, respectively. Stepped spillway models in numerical study include flat models and models with cubic elements placed on the steps in four arrangements of two side, zigzag, center, and hybrid AE elements and two heights of elements h/2 and h/4 (h step height). The commercially available CFD program FLOW-3D was used for the numerical simulations. The RNG k-ε turbulence model was employed for the turbulence calculations. To obtain mesh-independent results, three different mesh sizes were used, and the grid convergence index (GCI) methodology was employed to select the appropriate mesh. As a result, the mesh consisting of a containing block with a cell size of 1.3 cm and a nested block of 0.95 cm was selected. In the fluid domain, the boundary conditions were set according to the experimental conditions. In the upstream of the domain, a discharge flow rate (Q) definition was set. The downstream section was treated as an outflow (O) boundary condition. The bottom and the sides behave as rigid walls (W). For the upper boundary, the atmospheric pressure boundary, and at the inner boundary conditions, symmetry (S) was used. The results showed that the appendance elements on the steps cause some fluctuations on the flow surface and increase the intensity of the current collision by deviating the flow from its parallel path. The result is reduced velocity by about 10%, an increase of 54% in TKE, and an increase of 6.42% in energy dissipation on modified models compared to the flat stepped model. There was no negative pressure on the horizontal plane of the steps, and the maximum pressure occurred in the middle of the steps and inclined to the end of the steps. The appendance elements reduce the negative pressure areas on the vertical surface of the steps and reduce the risk of cavitation. The hybrid element model performs best in other arrangements, and reducing the height of the elements improves their behavior. According to the obtained results, it can be concluded that the appendance elements on the steps improved the hydraulic performance of stepped spillways by increasing the roughness of the steps, increasing energy dissipation, reducing the flow velocity over the spillway and reducing the risk of cavitation by reducing the negative pressure in the vertical plane of the steps. The use of cube-shaped elements on the steps and in the hybrid arrangement is suggested.

There are many different methods to modify the mechanical properties of saturated clayey soils. It may be chosen depending of location and function of the structure. among those methods, preloading in presence of vertical drains and installation of stone columns are similar together and it is the cause of comparison. In this thesis, each mechanism of modification of soil was studied lonely and then the results of every method were compared with all together. Subsequently the mentioned approaches were graded technicaly. For this reason, a two dimentional finite element software was used to make the models. It should be necessary to forcast the results of choosing one approach, because there is no proper procedure available for engineers to choose one of these method as the first index, and also the long time that must be spent for in situ consolidation.the results show that the finite element program has the ability of simulating the consolidation phenomena in saturated clayey soils and declare that installation of stone columns is better than preloading by installation of vertical drains. Of course, there are many parameters influences the selection of superiority.

Steel reinforced concrete (SRC) columns have become very popular in recent years due to their many advantages. In this study, to investigate the behavior of SRC columns with a cruciform steel section at their core, the ductility index and factors affecting it were investigated. Also, by calculating the necessary equations based on the plastic stress distribution method, a simple and practical method for designing these columns was provided. Accordingly, a finite element model was created using ABAQUS software for numerical study and was then validated with the results of a previous experimental study. A total of 16 columns with cruciform steel cores were analyzed for the present study. The effect of variables such as steel core percentage, concrete compressive strength, stirrup spacing, slenderness ratio, and load eccentricity ratio on the ductility index of these columns was discussed. The results showed that with increasing the eccentricity ratio, the bearing capacity decreases but the ductility index increases due to the change in behavior from compressive to flexural, such that as the eccentricity ratio increased from 0.1 to 0.4, the bearing capacity decreased by 59.1% but the ductility index increased by 28.2%.

In this paper, a new energy dissipative device named elliptical damper was introduced for passive control of structures. In the proposed damper, the energy dissipation capacity is provided by the shear deformation of the elliptical ring. To investigate the behavior of the proposed damper, a sample of this damper was tested experimentally. The results showed that the proposed damper had stable hysteresis loops and good energy absorption. Also, the finite element model was developed by considering nonlinear behavior, large deformation, and material damage. The results of the numerical model were verified through experimental results. The results showed that the numerical analysis could predict the cyclic response and damage location of the experimental sample. A parametric study was performed to investigate the changes in the cyclic behavior of the elliptical damper with its dimensions. Four independent parameters considered for this study are the greater diameter of the elliptical ring, the ratio of its diameters, the ratio of the thickness of the elliptical ring to its greater diameter, and the ratio of the height of the connection area to the greater diameter of the elliptical ring. Among the studied parameters, the thickness of the elliptical ring had the greatest effects, and the height of the connection area had the smallest effects on the cyclic response of the proposed damper. By increasing the thickness of the damper, the maximum strength and energy dissipation capacity increase, but its ductility decreases. The proposed damper has stable hysteresis loops, excellent ductility, and high energy dissipation capacity. The elliptical damper is simple in terms of construction technology and provides excellent energy dissipation capacity for the structure compared to the cost spent for its construction. According to the results, the proposed damper can be used as an appropriate energy dissipation device for passive control of structures.

One of the favorable structural mechanism to mitigate the progressive collapse in reinforced concrete structures and increase the load-carrying capacity is the mechanism of compressive membrane action. In the present study, for predicting the compressive membrane capacity, an analytical model for analysis of reinforced concrete beams is used. This analytical model is formulated based on a sectional analysis approach to establish equilibrium and compatibility conditions at each section along the length of the beam. Programming of the analytical model for analysis of RC beams was carried out with FORTRAN software. In order to investigate the membrane action in slender RC beams, several beam specimens with different span-depth ratio are analyzed in parametric studies. Analyzes are carried out to investigate the effect of four parameters of concrete compressive strength, reinforcement ratio, axial stiffness and rotational stiffness of the support on the membrane action in RC beams. The results show that with increasing the span-depth ratio, the effect of membrane action on beams decreases. It is also observed that the effect of all four parameters on the load-carrying capacity is greater in short beams. In evaluating the effect of support stiffnesses on the membrane action response, it was also observed that membrane action capacity increases with restraint stiffness only in the regime of weak restraints. Axial stiffness and span-depth ratio have the highest effect on axial restraint response, and also it is observed that rotational stiffness of the support and span-depth ratio have the highest effect on the maximum midspan deflection response.

Numerical models have the ability to simulate river flow by using mathematical relations under certain initial and boundary conditions. Investigating the capability of different models for simulating flow characteristics in a river reach such as flow depth, velocity and shear stress in river banks are one of the basic needs in river engineering. However, from the practical point of view, the minimum need for field information, the small computation, and the degree of trust of the application of mathematical models in the conditions of natural rivers is of great importance. The aim of this study is to integrate GIS and HEC-GeoRAS with HEC-RAS model in order to simulate the hydraulic parameters of the Karun River in Khuzestan province.

Seismic behaviour of shallow foundation on adjacent of the sand slope crest is evaluated in this article. The foundation of various engineering structures has been made of Shallow foundation adjacent to soil slopes. While the shallow foundation is placed in the slope or out of the slope the amount of static and dynamic bearing capacity is reduced. Static bearing capacity and dynamic bearing capacity (Seismic) have been made up of respective coefficients. In fact, when the ground slope is increased the quantitative amount of bearing capacity coefficient of shallow foundation is reduced. Bearing capacity of the shallow foundation has been investigated by various researchers. Respective researchers evaluate this problem when respective shallow foundation is on the slope in static circumstance. In respective condition, the sloe and shallow foundation are under seismic vertical, horizontal loads as well as the combination of respective loads. Seismic vertical and horizontal load effect analysis under horizontal and vertical seismic load condition could be evaluated by critical state methods in quasi-static loading technique. Two-dimensional finite element method, as well as the computational framework of the plane surface, have been used for numerical simulation in current research hypothesis. Shallow foundations have been placed at a certain distance from slope crest. The slope studied in this research has a 25-degree angle (2:1 - V: H).The respective slope has been constructed by sandy materials with medium density. Constitutive elastic models such as Mohr-Coulumb (MC) and Hardening Soil Model (HSM) have been selected for hardening effect evaluation. Actual seismic behaviour of the slope, shallow foundation as well as the direction of seismic response have been investigated innovatively. Research results are presented that two constitutive models (MC and HSM) have completely different response in the zone of the structural element of shallow foundation behaviour and geotechnical performance of dry sandy slope.

Interaction study on shaking tables is considered necessary for such devices to guarantee their operational accuracy in vibration simulation. In such studies, accurate estimation on dynamic characteristics of foundation of shaking tables and their neighboring soil is usually required. In this regard, experimental studies on the soil or on the foundation after its completion is recommended to reduce uncertainties in operation of the table in near future. In this work a forced vibration study on the foundation of a six degrees of freedom shaking table (to be operated by International institute of earthquake engineering and seismology) have been performed. In addition to the measured excitation information collected for determination of dynamic characteristics of the foundation, that part of the vibration that transfers to the soil (in different distances form the foundation) was also evaluated. Based on the results of such measurements, dynamic characteristics of the shaking table foundation using a single degree of freedom model is estimated. Later the magnitude and the frequency contents of the vibration that was transferred to the soil in distances up to 25 meters from the edge of the foundation (in both vertical and horizontal direction) was also determined. According to the results of this study, the level of transferred acceleration to the soil reduces, rapidly, by distance from the foundation. However, the results of these measurements indicates that, acceleration magnitude in the range of high frequency vibration remains untouched.

Side weirs are a type of hydraulic structures that can be used as a deviator structure for controlling and dispensation of discharge in flood and high velocity flows. The flow on these structures is spatially varied flow type with decreasing discharge. Due to the applications of side weirs for transferring and controlling discharge in flood flows and considerable velocities, its very likely to have supercritical flow on these kind of structures. Piano key and labyrinth side weirs can be used, when the width of the weir opening is limited. The increase in side weir's effective length relative to its opening is one of the advantages of these side weirs. The majority of studies done on the Piano key weirs had been limited to experimental methods, due to the limited conditions of laboratory, high cost and recent development in numerical models, its important to simulate these weirs in fluid dynamics software’s. In this research side weirs with different plans have been simulated by FLOW-3D. The FLOW-3D numerical model has been calibrated and verified for simulating side weirs using experimental results. Determination and presentation of the relation between the kinetic energy correction factor () and the momentum correction factor (β), discharge coefficient for Piano key side weirs in supercritical flow and comparing the shapes of piano key side weirs are some of the results of this research. These results can be used in designing these side weirs.

Using piles row is a well-known method to stabilize the soil slopes in the both static and seismic conditions. The load transfer mechanism of installed piles row may be as end- bearing or floating. In this study the behavior of floating piles row with circular cross- section were installed inside the dry sandy slope by help of three- dimensional numerical analyses and physical modeling have been simultaneously studied. The three- dimensional numerical modeling was used for conducting the parametric studies about effects of directions of imposition of near-field and far- field earthquakes loading on the main structural and geotechnical interaction parameters of floating piles row-sandy slope problem (Al-Defae and Knappett, 2015; Ashour and Ardalan, 2012).

Settling basins are one of the most important structures is commonly used for deposition of sediment particles in water and wastewater systems, in order to prevent the damage of sediment particles. The purpose of this study is to provide a one-dimensional numerical model for simulating flow and sediment in a rectangular sedimentation tanks. The governing equations are depth averaged equations of flow and sediment transport. In order to the numerical solution, the finite difference method has been used. The model can be used for non-uniform flow and non-uniform particles and could predict important information such as removal efficiency, thickness, and distribution of particle size of sludge. Comparison of the results of the proposed numerical model with the results of other researchers stated the acceptable accuracy of the proposed model, so that in all cases the error rate was less than 3%. The results of the sensitivity analysis showed that more than 50 percent of suspended sediment deposited at the first 5 meters of the basin; therefore, the increase in the dimensions of the rectangular reservoir is not the best way to improve the performance of the pond. In fact, increasing the removal efficiency can be achieved by reducing the depth of the settling basin, increasing the cross-sectional area of flow and reducing the surface loading rate.

Sea level rise and groundwater extrapolation lead to freshwater head changes at boundaries of coastal aquifers and causes further intrusion of seawater into aquifers. In the present study, the behavior of unconfined coastal aquifer to instantaneous sea level rise and freshwater head decline is investigated by physical and mathematical dispersive modellings. Three laboratory models have been conducted in a sand tank and salt wedge shape has been photographed over time. Salt wedge toe position, area of transition zone and volume of intruded seawater are measured for this purpose. The numerical results are in good agreement with experimental observations. The outputs derived by both modellings indicate that the instantaneous rise of head in sea boundary or significant decline of freshwater head in landside deforms the wedge shape of saline water, so that the seawater encroachment velocity at its tip will be faster than other regions. Moreover, establishment of an inverse hydraulic gradient (hydraulic gradient from sea to land) causes significant seawater delivery from sea into the aquifer. As a result, the salt wedge can even be stretched up to land boundary. Results of dispersive simulations demonstrate that when the velocity of saline water rises inside the aquifer, the advection role will be highlighted rather than dispersion. However, the longitudinal and transverse dispersivity will also increase and that consequently will widen the transition zone. Nevertheless, the increase rate of saline water volume has been achieved much higher than the growth rate of toe position and transition zone area.

In Iran, Dez dam has suffered from long flood-induced high turbidity currents. A major problem of this dam is sedimentation that has now blocked the irrigation gates. Mean annual sediment deposition in the reservoir is about 15 million tons. The level of deposited sediment is very close to the intake of power stations. The elevation of sediment deposition has now reached to nearly 14 meters under the intakes of power stations (Research center of power Ministry, 2003). In this study, a high resolution 3-D numerical model is employed based on nonhydrostatic Navier-Stokes equations, to investigate the dynamics of density flows resulting from the complicated reservoir morphometry.

In the present research, effects of a porous spur-dyke on the hydraulic characteristics of the flow in an open-channel have been numerically studied through non-linear Forschheimer model. The numerical simulations were performed in Flow3D package using RNG k-epsilon turbulence closure model. During simulations of the porous spur-dyke, suitable Friesheimer non-linear coefficients were determined for various cases with the sensitivity analysis. The sensitivity analysis and comparisons of the numerical results with the results of the physical model showed that most of parameters are completely dependent to Friesheimer non-linear term and the proposed software range for Friesheimer nonlinear coefficient is not suitable. The results showed that by increasing of the porosity of the porous spur dyke, the flow velocity and also the effect area of the maximum velocity will decrease. Also, by increasing of the porosity of the porous spur dyke, the upstream water depth of the spur dyke will decrease and the downstream water depth of the spur dyke will increase. It was also observed that by increasing of the porosity of the porous spur dyke, the maximum value of the velocity decreases and the minimum value of it increases.

Circular vertical Spillway with various inlet forms is very effective, when there is not enough space for the other spillway. Hydraulic flow in vertical circular spillway is divided into three groups: free, orifice and under pressure (submerged). In this research, hydraulic characteristics are investigated in vertical circular spillway by using numerical model. Hydraulic characteristics are investigated such as upper and lower nappe profiles, relation between discharge and upstream water levels, and discharge coefficient in numerical modeling and experimental conditions. The mesh with 10602 nodes, turbulent model k- standard and the standard wall function, provide the best results for modeling the flow in a vertical circular Spillway. There was a good agreement between numerical and experimental results in the upper and lower nappe profiles. In study of water level over crest and discharge, in low water levels, the results of numerical modeling are good agreement with experimental, but with increasing water level, the difference between the numerical and experimental discharge to be more. In the study of the flow coefficient, by decreasing in P/R ratio the difference between the numerical and experimental result increases.

In this study the behavior of floating piles row with circular cross-section were installed inside the dry sandy slope by help of three-dimensional numerical analyses and physical modeling have been simultaneously studied. The three-dimensional numerical modeling was used for conducting the parametric studies about effects of directions of imposition of harmonic seismic loading on the main geotechnical parameters of floating piles row-sandy slope problem. The seismic loading of harmonic sinusoidal waves in the form of seismic motions in the in-plane and out-of-plane directions along the longitudinal and transverse directions of slope model and both of them were imposed on the slope physical and numerical models. Moreover, the physical modeling of the investigating problem was implemented for validation of numerical results by imposing the sinusoidal harmonic loading in the longitudinal and transverse horizontal directions of micro-scale slope model by help of small-scale geotechnical shaking table. Reinforcing of a dry sandy slope by a row of floating piles (similar to reinforcing of slope by end-bearing piles row) results in significant decrease (to about more than 50 percent) in slope’s vertical displacements. Out-of-plane components of seismic loading such as transverse component of earthquake, T component, (productive of horizontal shear waves, i.e., SH waves) also in the presence of site’s effects such as “directivity effects” can produce the responses as large as the in-plane motion components such as earthquake longitudinal contained component, L (productive of P and SV seismic waves). The motion of slope sliding wedge in the strong ground motions is a rigid block motion while the failure wedge displacement under weak ground motions is a negligible motion and occur in a flexible block manner. Simultaneous seismic loading along two-axes of three coordinate axes in contrast to the current slope seismic loading that the seismic loading are imposed along one axis and in the longitudinal direction of slope failures surface, have great effects on the slope displacements values and internal efforts generated in the reinforcing piles row. Studying and solving the classic problem of in-plane and out-of-plane seismic-waves propagations in the combination with the existence of slope in the ground and piles row interaction (i.e., adding the piles row-slope seismic interaction to the initial classic problem) by help of present available analytical and mathematical solutions will be a very difficult problem. By combining of the in-plane and out-of-plane seismic motions the complexity of the piles row-sandy slope dynamic interaction problem will increase and in the some cases presenting analytical and closed-form solutions can be impossilble. The alternating solutions for solving these complex problems proposed by the present paper are the simultaneous using of numerical and shaking table physical modeling for understanding the precise details and ambiguities of the problem in the complete scientific and practical-empirical frameworks. The results of present study show that installing a row of floating piles similar to the end-bearing piles row can reduce the displacements of loose dry sandy slope and through this manner the seismic stability of slope against the local and general failures increased. In the present paper despite of increasing the directions of seismic loading from one-direction to the two-directions the installed floating piles row sufficiently played their roles in the reducing seismic displacements of slope. Indeed, according to the experimental-numerical results of the present paper, decreasing of slope crest settlements by installing a row of floating piles in the seismic loading cases are more than 50 percent. The results of small-scale 2DOF geotechnical shaking table physical model were used to verification of the obtained 3D numerical results. There is a good agreement between the numerical and physical models results.

Stress changes due to deep excavations will cause ground deformations near the excavated site. Deformation control in the vicinity of worn-out urban textures and important buildings is crucially significant. Prediction of ground deformation trends needs numerical modeling which should be calibrated with field studies; therefore, the accuracy of monitoring tool should be investigated in the field precisely. In this study, field monitoring and numerical modeling of an excavation stabilized by Top-Down method using total station in an overcrowded street in the city of Qom in Iran is implemented. In this project, construction sequences in Top-down excavation are monitored and the obtained data are analyzed frequently. Depending on the evolved information and the calibrated model, designation or construction stages in stabilization could be reconsidered to secure the excavation or to enhance the economy of the project. The quality of the gathered data in this method is of high importance which should be evaluated using statistical analysis to determine the precision of the monitoring tool. According to the conducted statistical analysis, the accuracy of Total Station in this study is appropriate for monitoring and construction technique in this project. However, using more accurate tools in monitoring high-risk excavations is emphasized.