Model Test Research Research Articles

Model Test Research on the Concrete Creep and Shrinkage Effects on the Long-Time Deflection of Steel Concrete Composite Beam

This paper presents a model test research on long-term deflection of prestressed steel-concrete composite beams caused by creep and shrinkage effects of concrete. The model is designed based on a 20.8m length segment of a service composite beam bridge in Guangzhou. Geometric scale between the model and prototype is 1:8. Long-term deflection of the test model was obtained through 300 days of uninterrupted test. In addition, using the CEB-FIP (1990) criterion, effective modulus of concrete was calculated considering the effect of the concrete creep and shrinkage. Uniform the effective modulus of concrete to the modulus of steel, the value of structures time varying stiffness was calculated with single material theory and the relationship between stiffness and deflection by introducing stiffness adjustment coefficients was established, then the value of deflection changing with time was calculated.

Model Test Research on Soil-Landslide Surge by River Channel Reservoir

By fully collected and surveyed on the soil landslide, with the help of generalized model, the experiment simulated the landslide occurrence and exchange process of soil landslide entered the water. Through the calculation and analysis of test results and influencing factors, it is given out the height of the initial surge, variation of the progressive surge and empirical formula of soil-landslide surge. Compared with experimental data, it is found that empirical formula has certain accuracy and it can provide a certain reference on surge disaster forecast.

Model Test Research of Surcharge Contribution to Ground Bearing Capacity

To investigate the influence of surcharge on bearing capacity, model tests were performed. In the tests, 5 kPa and 10 kPa surcharge was applied on silt respectively. The bearing capacity factor Nq is smaller than theoretical solution, and is only of 60.3% and 80.5% of theoretical solution. Model test show that the ground failure mode is not general shear failure mode in condition of ground under surcharge. In bearing capacity calculation, if bearing capacity factor theoretical solution which is from general shear failure mode is applied, the result will be overestimate.

Research on Stability of Slope by Influence of a Rapid Drawdown of Water Table

The importance of analysis of stability of slope during rapid drawdown of water table is firstly introduced in this paper. Through summary of the current theoretical and model test research on stability of slope during rapid drawdown of water table, the important of considering the matric suction in unsaturated soils, the analysis method of transient unsaturated seepage and safety of slope and the changes of slope safety was summarized and introduced in this paper. In addition, the problems existing in the analysis of stability of slope during rapid drawdown of water table are pointed out and some ideas for its further development are suggested.

Model Test Research on Excavation Technology of a Tunnel in Altered Granite Zone

Phenomenon of surrounding rock deformation and collapse, groundwater lowering, ground collapse and cracking appeared in a tunnel project. It is necessary to guaranty construction safety and ensure the reliability of supporting structures. This paper, using large-scale model, considers the surrounding rock deformations and stress adjustments caused by cavern excavation and tunnel support in the alteration zone. It suggests engineering protective measures by summarizing the major determinant of excavation deformation.

Model Test Research on the Pile Stress by Pseudo-Static Test of Pier-Foundation-Structure System

This paper mostly studied on the pile stress in the loess foundation when the pile and the soil are interacting by pseudo-static test of piers and piles in the remolded loess foundation indoor. We get the stress-depth curve of pile body. We get its finite element model by ANASYS and analyze the change of pile body stress.

Simple Harmonic Excitation Numerical Analysis and Experimental Study of Space Bidirectional Beam String Structure

In this paper,a two-way winding-beam space-harmonic excitation beam string under the action of the dynamic response has been studied to capture the dynamic response of the structure of the law, identify the structure of the weak components,and for the design and construction to provide the necessary theoretical data. Using ANSYS finite element software to numerical analysis and reduced scale quarter ratio of model test research methodology to study,using experimental test results and finite element numerical analysis of mutual authentication.Numerical analysis taking into account the geometric non-linear structure,carried out static analysis,modal analysis,harmonic analysis and transient response time-history analysis. Experimental studies of the dynamic signal acquisition and analysis and processing, through the comparative analysis of data, master of the winding space for a two-way steel beam string dynamic response law obtained structural response of the frequency response range,weak location and distribution of components of type of structural design and construction process were proposed.

Model Test Research of the Influences of Rock-Fall Impaction on Deformation of the Cut-and-Cover Tunnel Structure

On conditions of different weight，height, shape and the property of slope surface, the tunnel portal structure’s deformation evoked by rock-fall impaction has been researched in laboratory by using a 1/30 scale similar model. The study shows that there is a simple linear relationship between the structure’s deformation , the rock weight and the rockfall height when the slope gradient is 1:0.5 and the slope surface is slippery and the multiple linear relationship between the structure’s deformation , the rock weight and the rockfall height has been obtained. Effect of the shape of the rockfall and the property of slope surface on structure’s deformation has been comparative analyzed.

Model Test Research on Bearing Behavior of Pile-Net Composite Foundation in Super Large Area and Deep Soft Soil

Based on the treatment of in-situ foundation, two distinct model tests for pile-net composite foundation in super large area and deep soft soil with different pile spacing were designed to study the bearing behavior of the piles. The result shows: the axial force of pile shaft increases with the growth of embankment filling load and gradually rises down along pile shaft to a certain depth, then slowly decreases afterwards. The velocity of force changing varies from the correlated soil layers, which indicates that pile shaft resistance appears to be unlike in different pile sites; The ratio of pile shaft resistance area to the overall pile length is relatively high while of normal resistance area is smaller ,and when the upper load is mainly supported by bearing course on pile end, pile-net composite foundation turns to be friction and end-bearing pile; For each level of loads, both pile-soil stress ratio and load shearing ratio of pile increase modestly, then tend to be steady till the next load level is applying on.

Design and Experimental Model Test Research for Three Dimensional Heterotypic Interception Structure

In the article, the method of experimental model test is used to optimize the shape of the interception structure. The hydraulic characteristics including flow pattern, diversion ratio and water grade ling along the tunnel is studied minutely. Base on the initial design, the interception structure is revised, and the recommended scheme has been got, which properly meet the demands of hydraulic characteristics mentioned above.

Model Test Research of the Influences of Rock-Fall Impaction on Accelerations of the Cut-and-Cover Tunnel Structure

On conditions of different weight and height, the tunnel portal structure’s accelerations evoked by rock-fall impaction have been researched in laboratory by using a 1/30 scale similar model. The study shows that the normal acceleration value is the biggest, the lateral acceleration is second and the longitudinal acceleration is the minimum. There is a simple linear relationship between the structure’s acceleration, the rock weight and the rockfall height when the slope gradient is 1:0.5 and the slope surface is slippery. The multiple linear relationship between the structure’s normal acceleration, the rock weight and the rockfall height has been obtained.

Model Test Research on Mechanism of Geogrid-Reinforced and Pile-Supported Embankment

It has studied the characteristics of the work force of the geogrid-reinforced and pile-supported foundation through eight loading model tests, and analyzed the effects that varied pile spacing, reinforced floors, the paving position of the reinforcement have had on the stress concentration ratio of the pile to the soil of the geogrid-reinforced and pile-supported foundation, the pile axial force, the tension of geogrid.

Model Test Research on Subsidence of Geogrid-Reinforced and Pile-Supported Foundation

It has studied the subsidence characteristics of the geogrid-reinforced and pile-supported foundation through eleven loading model tests, and analyzed the effects that varied pile spacing, reinforced floors, the paving position of the reinforcement, underlayer thickness have had on the subsidence of the geogrid-reinforced and pile-supported foundation.

Study on Different Methods of Computing Consolidation Coefficient by Excess Pore Pressure Dissipation Datum on CPTU

Based on the different methods of computing the soil consolidation coefficient by excess pore pressure dissipation datum on CPTU, through computing the soil consolidation coefficient by different methods on the datum of CPTU model test and CPTU application research on Pearl River Delta, the applicability on different methods of computing consolidation coefficient by CPTU has been studied. The results show that on the computing value of consolidation coefficient, TB10041-2003 is more conservative; because of poor applicability on Strain Path Method and difficulty for obtaining t100 on Zhu-Xiaolin Method and α on Empirical Coefficient Method, some results can not be solved, so Strain Path Method and Zhu-Xiaolin Method and Empirical Coefficient Method are poor in engineering application; the computing way and the computing result on Zhang-Chenghou Method are similar with Torstensson Method with 50% consolidation degree. The achieved result can provide a foundation for further study for CPTU application research.

Model Test Research on Moisture Control of Saturated Over-Wet Soil

Based on laboratory model test, this paper presents the draining efficiency of vacuum pre-loading method and electro-osmosis method with over-wet soil in moist and rainy areas. The results show that: both methods can effectively reduce the water content of saturated over-wet soil in Ya’an area, to achieve the desired effect of drainage and consolidation; and the degree of the effects of both methods differ with spatial variation.

Model Test Research on Bearing Behavior of Improved Over-Wet Soil

According to the similarity theory, this paper presents a similar model with the similar geometric load and boundary condition to analyze the difference between untreated over-wet soil in Ya’an and improved over-wet soil. The test results show: the bearing capacity of improved soil is enhanced; the settlement of improved soil is much less than which of unimproved soil; the water stability of improved soil is strengthened. These means we have achieved the purpose of improving over-wet soil and the ash mixing method is a feasible means for dealing with over-wet soil.

Scale Model Test Research on Cable Supported Barrel Vault Structure

By setting cables and struts in place in the single-layer cylindrical latticed shell, a new-style prestressed spatial steel structure--cable supported barrel vault structure is constructed, the static load test research on which is carried out for the first time in this paper. Based on the prototype building, a scale model with the scale of 1:15 is designed and manufactured for the test. The research results indicate, the static behavior of the prototype structure can be reflected approximately by this scale model. The static behavior of the single-layer cylindrical latticed shell is improved significantly by adding cables and struts, i.e., the cable supported barrel vault structure is a kind of highly efficient prestressed spatial steel structure. Compared with the case of full-span load, the half-span load makes the cable supported barrel vault structure unsafer.

Interaction behaviours between parallel tunnels in soft ground

This paper describes a study of the influence of shield tunnel construction on the displacements and stresses induced in the linings of existing nearby parallel tunnels. The paper presents a brief review of a set of laboratory scale model test research programme investigated the influence of tunnel proximity and alignment, liner stiffness on the nature of the interactions between closely spaced tunnels in clay. A total of two sets of carefully controlled physical model tests were performed. A cylindrical test tank was developed and used to produce clay samples of Speswhite kaolin. In each of the tests, three model tunnels were installed in order to conduct two interaction tests that have been carried out to investigate the interaction problem between parallel tunnels. The results of these tests are compared with the results of finite element analysis to investigate the techniques that must be used to obtain reliable numerical solutions to this type of problem. The results presented here are limited to the comparison between the results of physical model test and the corresponding finite element back-analysis. The results of the physical model tests generally indicate that interaction effects are greatest on the pillar springline and crown of the instrumented tunnel. It was also generally observed that the total stresses acting on the instrumented tunnel decreased immediately after a non-instrumented tunnel had been installed. These stresses tended to increase in the long term as pore-pressure dissipation occurred. These results also indicate that significant bending moments were induced in the instrumented tunnel by installation of the new tunnels. In both cases, the numerical and model test data agree well. It is also found that the closer new tunnels are constructed to an existing tunnel, the larger additional moment is developed at the pillar springline of the existing tunnel liner. The physical model tests show that for closely spaced tunnels the distortions and moments of the liner may be important. The values of the bending moments induced in the liners appear to be particularly significant. It is shown that interaction between tunnels is unlikely to be significant unless the spacing between the tunnel centres is less than about two tunnel diameters. Elastic finite element analysis with a hydrostatic gap modelling procedure gives results that appear to be in good agreement with the results of the physical model tests. Based on the results of finite element analyses performed to verify experimental procedure, it is suggested that the procedures adopted in the model tests of using one clay sample to carry out two interaction experiments is reasonable. (A). Reprinted with permission from Elsevier. For the covering abstract see ITRD E124500.

Three-dimensional model test research for tunnel group : Han Boli; Chen Xialing Proc international symposium tunnelling for water resources and power projects, New Delhi, 19–23 january 1988v1, p83–87. Publ New Delhi: Oxford and IBH Publishing Co, 1988

Three-dimensional model test research for tunnel group : Han Boli; Chen Xialing Proc international symposium tunnelling for water resources and power projects, New Delhi, 19–23 january 1988v1, p83–87. Publ New Delhi: Oxford and IBH Publishing Co, 1988