Full-scale Model Experiments Research Articles

Experimental and Numerical Investigation on Group Anchor Performance of Wooden Bolts in Rammed Earthen Sites

ABSTRACT Challenges remain in understanding the interaction mechanisms and influencing factors of multi-anchor systems. To investigate this matter, this study conducted nine full-scale model experiments examining the pulling resistance and failure modes of wood bolts embedded in rammed earth. These experiments varied bolt numbers (2, 3, 4), spacings (500 mm, 1000 mm, 1500 mm), and embedment depths (200 mm, 300 mm, 400 mm). Key factors and their levels for the group anchoring effect in the model tests were determined through orthogonal analysis. Among these factors, embedment depth exerted the most significant influence on pulling resistance, followed by bolt spacing and number. Furthermore, a numerical simulation method for wooden anchor group systems was developed using the “contact surface” element in FLAC 3D finite difference simulation software. This method considered factors such as bolt number, spacing, edges, embedment depth, and the layered nature of the compacted soil. It analyzed stress distribution and transmission laws across various interfaces within the anchoring system and the compacted soil, thereby supplementing and expanding upon the findings of the model experiments. These findings enhance understanding of the complex interplay between multi-anchor systems and soil, providing a scientific foundation for analyzing mechanical behavior in similar anchoring applications.

Full-scale experimental investigation into stability of segment-SCC-steel tube lining under external pressure

To investigate the mechanical deformation characteristics of the ‘Segment-SCC-Steel Tube’ combined bearing lining structure under internal and external pressure, the loading device and monitoring system for the stability analysis of the full-scale lining were proposed. The effect of cracked encased concrete and local external pressure on the instability mode of thin-walled steel pipes was explored by full-scale model experiment and three-dimensional FEM numerical simulation. The influence of SCC (Self-Compacting Concrete) and stiffening rings on the stability of steel pipes subjected to external pressure was discussed. The results show that SCC cracks occur and intensify with increasing internal pressure. The external water acts directly on the steel tube through cracking, resulting in wavy deformation, and the gap between the SCC and steel tube further increases. When calculating the critical external pressure for the steel pipe, the constraint of encased concrete can be ignored, and only the constraint effect of the stiffening ring can be considered. Therefore, the Von Mises formula was used to predict the critical external pressure between the stiffening rings with high accuracy. In addition, the stiffening ring can mitigate the crack propagation of nearby SCC. The steel tube remained in the elastic stage under internal pressure. In the full-scale experiment, the external pressure could not continue to rise after reaching 0.65 MPa. Nevertheless, the amplitude of the buckling wave continued to increase. It is considered that the steel pipe is in an unstable state, and the failure mode is dominated by single-lobe buckling.

Sound transmission through reconstructed middle ear using a full-scale model experiment

Tympanoplasty is surgical operation performed for intractable otitis media which is chronic otitis media and chronic suppurative otitis media with cholesteatoma and has multiple types depending on the patient's medical condition. This includes ossicle reconstruction by inserting reconstruction material to restore hearing, but there are some cases in which postoperative hearing performance is poor, and no expected knowledge has been obtained. There are some studies about the mechanism of sound transmission through human intact middle ear, but we have not yet obtained enough information on the mechanism of sound transmission through the reconstructed ossicles. In this study, the hypothesis that differences in sound transmission occur due to differences in the type of the reconstructed model was verified by measuring the displacement of stapes footplate with laser doppler vibrometer in a full-scale model experiment modeled on external auditory canal, tympanic membrane, and ossicles.

中山間地域における地域防災レジリエンス向上のための落石対策工に関する研究

For Japan, one of the world's leading “disaster-prone countries,” measures are required to reduce or prevent damage caused by disasters as much as possible to ensure the people's safe and secure lives. As a measure of that, developing a solid transportation infrastructure and a lifeline is indispensable. Against this background, this paper considers road-slanting surface countermeasures that assess the soundness of lifelines often constructed along roads, using the mountainous areas of Kochi Prefecture as a model. On that basis, we proposed a new "rock-fall countermeasure construction method" (from now on referred to as "ORN method") that is effective and highly versatile in preventing road slope collapse and rock-fall events. Specifically, we planned to increase the space between props so that it could be applied to valley-shaped slopes and to strengthen the potential absorbed energy by adding reinforcing ropes. In addition, the outline and design calculation results of this ORN construction method were presented, structural rationality was explained through the consequences of full-scale model experiments, and the effect of improving regional disaster prevention resilience by adopting the construction method was also mentioned

Fatigue evaluation and structural optimization of rib-to-diaphragm connection in orthotropic steel decks

The fatigue cracking at transverse diaphragm cutouts and rib-to-diaphragm connections is one of the primary ways in which orthotropic steel decks (OSDs) are damaged. In this study, the fatigue damage mechanism of the cutouts and rib-to-diaphragm connections was investigated through a full-scale model experiment and numerical simulations. The applicability and accuracy of different fatigue evaluation methods for the cutouts and rib-to-diaphragm connections were compared. Furthermore, the fatigue behavior of the novel rib-to-diaphragm connection was evaluated, and its optimized structure was suggested based on parametric analysis. The results show that a complex stress distribution dominated by in-plane stresses was observed at the rib-to-diaphragm connection under wheel loading. The cracking of the weld toe at the transverse diaphragm side was found to be the dominant failure mode. The hot spot stress method has a higher prediction accuracy than the critical distance theory for predicting the fatigue life of the cutouts. For the longitudinal rib-to-transverse diaphragm connection, the hot spot stress method could be used to predict the fatigue life of U-rib side weld toes based on fatigue grade FAT 90, and the equivalent structural stress method provided a reasonable prediction of the fatigue life for all fatigue failure modes. Last but not least, a novel rib-to-diaphragm connection structure that can effectively improve fatigue performance was suggested, and its fatigue life was evidenced to be greater than 50 million cycles after geometrical parameter optimization.

An Improved Emergency Blow Theoretical Model for Naval Submarine Blowing System and Experimental Verification

_ An improved emergency blow model is proposed, which is based on the traditional emergency blow model and takes into account the influence of compressed air overflows from flood holes in the later stage of blowing. In order to verify the prediction accuracy of the improved emergency blow model for tank blowing, the full-scale model experiment of tank blowing was conducted to investigate the effects of air source volume, air source initial pressure, and flood holes diameters on blowing. The process of air release from bottle and main ballast tank drainage can be accurately simulated by the improved emergency blow model, and the prediction error of tank air peak pressure is shown to be <10%. Additionally, it is found that the air source volume has no effect on the tank’s air peak pressure or tank drainage rate. By analyzing the dynamic characteristics of tank air pressure, it is found that the dynamic change trend of air pressure differs between flood holes with small and large diameters. In the small diameter conditions, the air pressure reaches the maximum when the compressed air just enters the tank; however, under large diameter conditions, the peak pressure comes before the accumulated air pressure is released. The experiment and simulation demonstrate that increasing the area of the flood holes has a decreasing effect on the amount of air accumulated in the tank, and that the decreasing effect becomes more pronounced as the air source initial pressure increases. Introduction To carry out military operations, submarines are deployed both underwater and close to the open surface. About 170 submarines have sunk since they were originally created as a result of an accident, such as a fire, explosion, malfunction, grounding, or collision (Park & Kim 2017). Submarines run the risk of losing safety control in these critical situations. The best method of self-rescue is emergency floating to the surface to prevent bottoming or going deeper than allowed (Liu et al. 2009). A key factor in emergency rising to the water’s surface is the compressed air blowing mechanism. In such an operation, supplying air to the main ballast tank and blowing out ballast water should be used to achieve positive buoyancy or recover a positive pitching moment, which can be used to restore the safe depth of the submarine. Emergency blow is the term used to describe the process of directly supplying air to the main ballast tank without using a high-pressure valve column. The emergency blow is explored in this work because its influence is significantly greater than that of usual blowing, or traditional blowing.

BEARING CAPACITY OF T BEAM UNDER DIFFERENT PRESTRESS LEVELS: FULL-SCALE EXPERIMENT AND FEM ANALYSIS

Insufficient prestress will cause cracks in the T beam, which will influence its stiffness and bearing capacity. This paper is devoted to studying the influence of prestress levels on the bearing capacity of T beam, and then judging its working state. A full-scale model experiment is carried out on the 13 meters prestressed concrete T beam. At the same time, a nonlinear finite element model is established and verified. The experimental results show the numerical simulation results are in good agreement with the experimental results. Finally, the finite element model is used to make a simulation of the bearing capacity of T beams under different prestress levels. The mathematical relationship between prestress levels and bearing capacity is obtained based on the results of the finite element model. The relationships between the mid-span deflection and load of the experimental beam are basically the same under different prestress levels, both including three stages: elastic stage, crack development stage and failure stage. With the increase of the prestress levels, the stiffness of the experimental beam before cracking is improved significantly.

Full-Scale Model Experiment on Remediation of Heavy Metal in Contaminated Clayey Soil by Wsl-Gc-Cw Method

Full-Scale Model Experiment on Remediation of Heavy Metal in Contaminated Clayey Soil by Wsl-Gc-Cw Method

Full-Scale Model Experimental Research on Concrete Construction Technology of Steel Shell Immersed Tube Tunnel

A full-scale model experiment was carried out to research the effects of the Self-Compacting Concrete (SCC) construction technologies including SCC working performances, casting speeds and the arrangement methods of vent holes on the filling quality of the steel shell immersed tube tunnel compartments. The experimental results showed that in order to guarantee the bearing capacity of structure mainly by reducing the voids as many as possible to meet the related requriements of Guide, the total area ratio of voids with the depth more than 5.0 mm in the whole top surface of compartments must be less than 5%, the initial slump flow of SCC should be improved to 670±50 mm on account of the flowability loss caused by the particle migration of coarse aggregates during pumping and at least ten vent holes distributed around the top plate of a steel shell compartment parts of which were located on the both ends of T ribs far from the pouring holes are needed, simultaneously the appropriate pouring speeds of SCC are respectively 30 m3/h and 15 m3/h when the distances from fresh concrete level to compartment roof are more and less than 20 cm.

The research on minimizing the induction between the transmitting and receiving coils in close range transient electromagnetic inspection of groundwater-related defects in the operating tunnels.

The striking dominance of groundwater-related defects in the operational high-speed railway tunnels in China calls for swift and accurate detection and identification. Thus, it is a new attempt to detect the water-bearing defects at 5 to 10 meters via train-borne transient electromagnetic method in operating tunnels. Due to the short detection distance, the interaction between transmitting and receiving coils is more important than those normally used coils. Thus, numerical and experimental methods are combined to investigate the mutual induction. The influence of turns, current and coil size on the mutual induction and the impact of damping coefficient on the receiving system are manifested. To further verify these findings, full-scale model experiments are conducted. During these physical experiments, the detection results of different coil parameters including coil size, number of turns, and emission current are compared and analyzed. Then, a special effort to minimize the induction between transmitting and receiving coils is expended to acquire the suitable coils for close range detection in the tunnel context. Finally, in order to verify the availability of the detection system, different detection distances are conducted. It turns out that different detection distances have slight difference at the detection results, but they are still within the measuring range of the detection instrument. Obviously, these findings can provide theoretical support for the detection of water-bearing anomalies in operating tunnels and it also has reference significance for the detection of anomalies at close distance.

Factors influencing the airflow rate of kitchens in cooking exhaust shaft system of high-rise residential buildings

Insufficient shaft cross-sectional area of cooking exhaust shaft system in high-rise buildings influences the ventilation capacity of range hoods in kitchens, which cause damage to human health or increase the energy consumption of the building. There are numerous factors that affect ventilation capacity of the exhaust system, such as exhaust shaft cross section, range hood performance, operating rates and distribution of range hoods. The purpose of this research is to conduct a quantitative study on the effects of these parameters on the airflow rate of kitchens. A theoretical model of the cooking exhaust shaft system was established according to the Fluid Network Theory, it was further validated by a full-scale model experiment and used to calculate the airflow rate of kitchens for a 33-storey residential building. The results show that when the exhaust shaft cross section is designed to be 500 mm × 400 mm according to standard, regardless of the performance of the range hood, the airflow rate of kitchens of some users will be either insufficient or excessive, and cannot meet 300~500 m3/h required by Chinese standards. But when the shaft cross section is 750 mm × 600 mm and the standard range hoods are used, the airflow rate of kitchens can reach 300~500 m3/h at any operating rate. The established model can be applied in other countries to study the ventilation effect of the similar cooking exhaust shaft system in residential or other buildings. The research results can be useful for improving the design of the cooking exhaust shaft system in residential buildings.

The DEM study of segregation phenomena of burden distribution during the charging process of blast furnace with two parallel hoppers

ABSTRACTThe segregation phenomena of burden distribution were analysed by the discrete element method in detail, and the calculation result of burden falling locations was validated by full-scale model experiment. The calculation results show that large particles mainly gather in the sub-centre and wall region of the stock surface, but the small particles mainly stay in the centre and platform region of the stock surface, and the size distribution of coke depends on the hopper structure mostly. The burden layer thickness is not symmetric in the radial direction of the stock surface owing to the particle velocity at the outlet of rotating chute is not stable, and the mass distribution of coke is also not uniform in the circumferential direction of the stock surface as the delay angle of the falling point is not constant.

Effect of Deficiencies in the Tunnel Crown Thickness on Pressure Tunnels with Posttensioned Concrete Linings

This paper investigates the effect of deficiencies in the tunnel crown thickness on pressure tunnels with the posttensioned concrete lining. Based on the lining parameters of the Yellow River Crossing Tunnel, the modeling approach of the posttensioned concrete lining is introduced in detail and a three-dimensional finite element model is established. The three-dimensional finite element model is validated by experimental results from the full-scale model experiment of the Yellow River Crossing Tunnel. Special attention is given to the changes in the deformation, radial displacement, and circumferential stress of the posttensioned concrete lining with gradual decreases in the tunnel crown thickness. The calculation results show that the influence scopes of deficiencies in the tunnel crown thickness are mainly concentrated in the crown and its adjacent parts. The posttensioned concrete lining can still maintain a satisfactory stress state when deficiencies in the tunnel crown thickness exist, and undesirable stress levels may be caused only when the tunnel crown thickness decreases below a certain threshold. Furthermore, cracks are most likely to occur at the external and internal surfaces of the crown and at the internal surface of the crown’s adjacent parts, which is useful for taking measurements regarding the lining tightness and stability.

Characteristics of Groundwater Response to Precipitation for Landslide Prevention at Kiyomizu-Dera

Every year in Japan, slope failures often occur due to heavy rainfall during the wet season and typhoon season. The main reasons for soil failure are thought to be the increase of soil weight from infiltrated precipitation, the decrease in shear strength, and effects of the increase groundwater elevation. It is therefore important to consider to characteristics of groundwater behavior to improve slope disaster prevention. Kiyomizu-dera experienced major slope failures in 1972, 1999, and 2013, and a large slope failure occurred nearby in 2015. The two most recent events occurred since observation of precipitation and groundwater conditions began at the site in 2004. In this research, we determine the relationship between rainfall and groundwater level using both a full-scale model experiment and field measurements. Results indicate strong connection between rainfall intensity and the velocity of increase in groundwater level, indicating that it is possible to predict changes in the groundwater level due to heavy rainfall.

Probabilistic Analytical Model for Settlement Risk Assessment of High-Speed Railway Subgrade

AbstractIt is crucial for the design and operation of a high-speed railway to estimate and control the accumulative settlement of the subgrade induced by cyclic train loading. In this study, an analytical model, considering the effect of the initial stress state, is proposed to predict the accumulative settlement of high-speed railway subgrade. Dynamic load triaxial tests are conducted to determine the parameters involved in the computational model. Full-scale model experiments are carried out to verify the effectiveness of the proposed computational model in predicting the accumulative settlement of high-speed railway subgrade. A probabilistic analytical model is developed for a reliability-based settlement risk assessment of the subgrade by considering the uncertainties and randomness of the relevant parameters. The coefficient of variation (COV) of the dynamic stress on the subgrade surface caused by train loading is derived from field data measured on the Wuhan-Guangzhou High-Speed Railway, China. A M...

Numerical simulation of transient flow in horizontal drainage systems

A numerical simulation model based on the characteristic-based finite-difference method with a time-line interpolation scheme was developed for predicting transient free surface flow in horizontal drainage systems. The fundamental accuracy of the numerical model was first clarified by comparison with the experimental results for a single drainage pipe. Boundary conditions for junctions and bends, which are often encountered in drainage systems, were studied both experimentally and numerically. The numerical model was applied to an actual drainage system. Comparison with a full-scale model experiment indicates that the model can be used to accurately predict flow characteristics in actual drainage networks.

Full-scale experiment and CFD simulation on smoke movement and smoke control in a metro tunnel with one opening portal

Three full-scale model experiments were conducted in a unidirectional tube, which is a part of a metro tunnel with one end connected to an underground metro station and the other end opened to outside in Chongqing, PR China. Three fire HRRs, 1.35MW, 3MW and 3.8MW were produced by pool fires with different oil pan sizes in the experiments. Temperature distributions under the tunnel ceiling along the longitudinal direction were measured. At the same time, CFD simulations were conducted under the same boundary conditions with the experiments by FDS 5.5. In addition, more FDS simulation cases were conducted after the FDS simulation results agreed with the experimental results. The simulation results show that the smoke temperature and the decay rate of the temperature distribution under the tunnel ceiling along the longitudinal direction increase as HRR increases. The smoke exhausts effectively from the tunnel under mechanical ventilation system, whether the emergency vent is activated as a smoke exhaust or an air supply vent. The operation mode of the mechanical ventilation system depends on the evacuation route.

Study on the Performance of Reinforced Embankment on Mountain Slope Using Full-Scale Model Experiments

The full-scale model test is used to study the stability and deformation control of reinforced sloped embankments on mountain slope foundation. According to practical experience in the expressway construction in the mountain region, two full scale model experiments were carried out in laboratory. One model is reinforced by geogrid and the other is un-reinforced in the embankments. The design of the model, test data and analysis methods are emphatically introduced. During the experiments, some key test data were monitored, such as the vertical and horizonal displacements distribution of slope, the vertical displacement on the top of the embank, the internal stress and displacement distribution, the form and position of the slip curve surface in the two embankments. Comparing experiment of reinforced with un-reinforced, it shows that the lateral displacement of embankments of the former is smaller and the stability of embankments is higher than that of the latter. The model experiment results can give reference for the construction of China's western mountain highway.

Improvement of sound insulation of doors or windows by absorption treatment inside the peripheral gaps

Slit-shaped gaps included in such building elements as doors and windows are apt to deteriorate sound insulation performance of the wall system. In order to reduce sound transmission through these parts, sound absorption layer is often put inside the gaps. In this study, the effect of such a sound absorption treatment was examined by numerical and experimental studies. In the numerical study, the effect of sound absorption treatment on the gaps existing around doors/windows was examined by applying the FDTD method. To examine the results of the numerical study, a full-scale model experiment was performed using the sound intensity measurement method. A considerably good agreement was found between the results of the numerical study and those of the experimental study. As a result, it has been indicated that the sound insulation defect caused by the sound transmission through the gaps can be much improved by sound absorption treatment inside the gaps. Narrow gaps which exist around the door panel or window sash are apt to deteriorate sound insulation performance of the total wall system. The influence of the acoustical transmission through the gaps or apertures has been theoretically investigated [1-6]. More practical case studies on sound insulation performance of such real building elements with gaps as doors and windows has also been investigated [7-11]. However, prevention of sound transmission through such peripheral gaps has not been reported. In this study, therefore, we examined the effect of sound absorption treatment in narrow gaps with various shapes in cross section. As a case study, in-situ measurement of sound insulation performance of a door panel in an office building was performed under the conditions of with and without absorption treatment.

The Research on the Steel Asphalt Isolation Pier by a Full-Scale Masonry Model

In view of the universal present situation where general rural buildings has low earthquake resistance ability, this paper, based on the base Isolation theory and the steel-asphalt isolation layer, proposes the steel-asphalt isolation pier to overcome the shortcomings of relatively complex construction and inconvenient volume production. The present study has also carried full-scale model experiment on the houses of single-layer full-scale masonry structure. The result shows that with the sine wave input of different acceleration amplitude, the superstructure acceleration weakens more than 40% and gets good damping effect because a majority of seismic energy has been absorbed by the isolation pier; and when the acceleration amplitude is below 0.30 grams, the steel of isolation pier is to be at the elastic state and can reset automatically after shock, which can satisfy the requirements of the seismic design. However, in order to meet the demand of the topic research, the present study has only done experiment on the small earthquake. According to the research findings, the attenuation coefficient , on the whole, tend to increase with the increase of acceleration peak value.