Applied Mechanics and Materials Vols. 97-98

Abstract: In recent years, frequent earthquakes had happenned everywhere in the world.Through establishing soil dynamic constitutive model and boundary conditions, implement finite element numerical analysis of embankment high slope of different filling, using large geotechnical software GEO–SLOPE, inputting El Centro wave, Taft wave and artificially wave according to requirements specification fitting respectively in this article.Results show that different degree earthquake will reduce the stability safety coefficient of embankment slope, the properties of embankment high slope of different filling is worse,the range of reduction is larger.

Abstract: Based on the geometry irregularity of pavement, an expression of the traffic load was put forward. The influence law of design parameters of each part of highway and geometry irregularity of pavement on dynamic response of highway was discussed by the developed two-dimension finite element numerical analysis procedure. The research shows that the vertical maximum vibration acceleration of pavement and subgrade attenuates according to certain trend along depth direction in different work conditions; with the foundation stiffness increasing, the vertical maximum vibration acceleration of base course and cushion increases gradually, and that of pavement surface, subgrade and foundation decreases, and the decreasing amplitude increases gradually along the depth direction; the size of the influence of subgrade on dynamic response of highway is relevant to itself stiffness; the rational matching of all parts of highway can effectively reduce the vibration response; with the increase of geometric irregularity index, the vertical maximum vibration acceleration and maximum dynamic stress of pavement and subgrade increases significantly.

Abstract: Based on the equivalence principle of bending deflection and torsional displacement, the concentrated vertical load which acts on the center of a continuously reinforced concrete pavement (CRCP) is translated into an equivalent half-wave sine load by Fourier transform. On the basis of this transform and deformation harmony condition of crack, the equations of load transfer are established. According to the translation principle of the force, the equations of load transfer of adjacent slabs are worked out. With the small deflection theory of elastic thin slabs, the bending deflection and torsional displacement formulas of CRCP under the concentrated vertical load with hollow foundation are deduced, which is verified by the results of finite element(FE). The results show that the characteristic of CRCP after cracking is related to the rigidity factor which is proportional to the spacing of adjacent cracks and the width of CRCP.

Abstract: The highway in earthquake region suffered serious damage during Wenchuan’s Earthquake in 2008. In all projects of post-disaster reconstruction, the reconstruction of highway and making highway work once again are prerequisite. There are a plenty of rock fall, dangerous rock, landslide, and debris flow sections along the highway between epicenter areas Wenchuan County to Li County. Among the post-disaster reconstruction of the highway, efficiently solvement of these disaster or potential disaster is one of geotechnical engineering topics. Phyllite rock occurs in large number along the highway but is defective fillings. This kind of material if not made full used, it will be able to lead to filling shortage and environmental disruption. How to treat it as a resource for roadbed fillings is the second of the important geotechnical engineering topics in the highway reconstruction. There are many narrow sections along the highway, and Inside Mountain is not stable. Common anti-skating retaining wall is not fit the severe condition because of its basement dug being harmful for mountain slope steady. How to pass this kind of sections is also bottle neck technique. The above technical problems are analyzed and the relevant solutions are proposed. So the troubles are solved efficiently and the highway is open to traffic on schedule. The terms of settlement provide reference for similar highway reconstruction projects.

Abstract: In this article, the waterproof curtain, the underground diaphragm wall and the soil between them are regarded as superposed combined exterior protected structure, then build a flexible spring support system. When using senior ANSYS finite element analysis program to simulate the strained condition and displacement of the underground diaphragm wall, we will combine with the monitoring result and the result of traditional comouting method. After contrasting, we can get a conclusion: the strained condition and displacement of the wall of this simulation method are more coincident with practical projects, and can reduce unnecessary waste.

Abstract: Strength reduction elasto-plastic finite element analysis defines the reduction factor when slope has been destroyed as the slope stability factor of safety, which combines with strength reduction technique, the limit equilibrium theory and the principle of elastic-plastic finite element. Three-dimensional finite element analysis should be used in stability analysis of slope because it can overcome the short advantages of two-dimensional finite element and can simulate the complex topographic and geological conditions. Based on the large-scale triaxial shear test, the modified Duncan-Chang model is established. Based on strength reduction elasto-plastic finite element, stability of high fill embankment was studied with three-dimensional finite element method considering the complex terrain conditions. Study results suggest that plastic strain and displacement mutant of slip surface node can be a sign of slope instability as a whole. At the same time calculation of three-dimensional finite element also does not converge. Therefore, it can be slope instability criterion calculate whether the finite element static analysis converges or not. On the other hand, stability safety factor of high fill embankment under three-dimensional conditions is larger than that of two-dimensional conditions, which shows that boundary conditions of high fill embankment enhance its stability.

Abstract: This article carries on the test to materials of the roadbed and the pavement in the room, and obtains mechanics computation parameter; Considered the road overload situation, we carries on the modeling computation to the typical semi-rigid bituminous pavement structure through using the finite element software; Carrying on the analysis, we obtains the correlation formula between the road deflection and various structures level maximum stress .it can provide the theory basis and the instruction experience for the highway pavement structure design, the examination and the construction control.

Abstract: In this paper, visco-elastic-plasticity theory is employed to establish a nonlinear finite element model of the asphalt mixture pavement. The influence of pavement structure, the ability of rutting resistance of middle layer and traffic load on shear stress distribution for asphalt pavement are discussed. The numerical results show that shear stress analysis can be used to analyze the rutting of asphalt pavement. The asphalt materials of middle layer have a great impact on rutting and shear stress. Modified asphalt is a useful middle layer material to decrease the rutting, and the hard asphalt is also an economical material to reduce rutting. Overload and overpressure easily cause pavement rutting damage. Pavement longitudinal grade is not the main reason leading to rutting at the long slope, but brake frequently in the long slope is the real cause of rutting.

Abstract: This research applies Negative Binomial regression models to investigate safety effects of ramp spacing. Data for model estimation was collected in 112 freeway segments where each entrance ramp is followed by an exit ramp. Three years (2005-2007) of freeway crash data were examined by the NB model in this study. The modeling results suggest that the frequencies of total crashes, fatal-plus-injury crashes, single-vehicle crashes and multiple-vehicle crashes increase as ramp spacing decreases, and the frequencies of total crashes and multiple-vehicle crashes increase at significant rates. The modeling result has been geared into the development of accident modification factors (AMFs) for ramp spacing that can be used safety prediction of freeways.

Abstract: By comprehensive analysis and design optimization of barrier structure parameters, a new type of beam-and-post steel barrier was invented according to impact test condition and acceptance criteria of cross-sea bridge barrier. Full-scale impact tests and finite elements analysis were conducted to do safty evalution of the barrier. The results show that, ASI value is 1.62 for test and that is 1.67 for FEA, THIV is 30.7km/h for test and that is 31.2km/h for FEA. Working width is 0.88m for test and that is 0.62m for FEA. Occupant risk evaluation index can meet the requirements of level B and the working width can meet the requirements of level W3. Both of tracking and posture of vehicles are well. The study results above show that safety performance of cross-sea bridge barrier can meet or exceed the acceptance criteria. FEA results are consistent with Full-scale impact test, which validate the reliability of FEA. cross-sea bridge barrier can meet the highest test level for beam-and-post steel barrier, which can defend the out-of-control vehicles effectively and help to ensure the bridge safety.