Advanced Materials Research Vols. 168-170

Abstract: The dynamic response of underwater structures is different from those in air because of interaction between fluid and solid. The influence of water depth on dynamic effect of the pier is studied base on a cable-stayed bridge in deep water. The girder of the cable-stayed bridge is simplified as a lumped mass on the top of the pier. The three-dimensional finite element models of pier with different water levels are built to calculate the dynamic characteristics and dynamic response of the pier under the action of harmonic load. The calculated results show that with the rise of water level, the nature frequencies of the pier decrease while the displacement and stress increase.

Abstract: China is undergoing rapid economic growth and urbanization. On the one hand, in the critical period of the rapid development, the rapid expansion of high-speed railway lines makes more and more various bridges go across the river channel. On the other hand, in our country the traffic density of each river channel is ever increasing, and ships are in large-scale and rapid development stage. The conflict of shipping transport with old bridges or new bridges becomes very prominent. The causes leading to the conflict are due to the factors, such as the geological change in hydrology, bridge design defects, the deficiency of anti-collision measures, shipping mismanagement, bad weather conditions, shipping equipment failure, ship-owner’s misjudgments, and so on. By investigating the ship-bridge collision accidents occurring in the bridge construction and operation in China since 2007, this paper analyzes the natural and human factors, studying large or small influence of various factors and their solutions through typical cases. It may be helpful for the bridge design and management across the river channel in the future.

Abstract: It exist non-linear flow in soft clay, which is caused by the shear flow situation of bounded-water. In this case, permeability coefficient is a nonlinear function of hydraulic gradient. With the discharge of pore water, the effective stress is increasing, and part of weakly bound-water begins flow, while the porosity and permeability are became lower. By taking into the characteristics of the pore water, it is established a model, which is explained the nonlinear flow of clay, and shown that, with the increasing of and , the consolidation time is obviously increased

Abstract: As one of complex body, the strength of reinforced lime-soil with wheat straw was influenced by many factors. In order to gain quantitative contributed proportion, traxial compression tests of reinforced lime-soil, which took some factors like reinforced length, reinforced ratio and consolidation in account, were carried out by orthogonal design, and then evaluated by methods of range analysis and principal component analysis. Results are as follows. (1) Contributed proportion of consolidation is the highest, while, successively, of reinforce ratio and of reinforced length. Consolidation has the positive contribution to cohesion which the correlation coefficient can be up to 0.81, however, reinforced ratio takes negative contribution and the correlation coefficient is (-0.71). (2) The optimal reinforced condition of wheat straw is 20 mm in length and 0.25% in ratio as to the sample diameter of 61.8mm. (3) Results of principal component analysis and range analysis are both corresponded with that of experiment. These two kinds of statistics analysis methods are suitable in the domain of reinforced soil.

Abstract: In this paper, styrene-butadiene polymer emulsion SD622S was adopted to modify cement mortar; mechanical properties of cement mortars were studied and microstructures was analyzed by means of Scanning Electron Microscope (SEM) and Specific Surface Area & Pore Distribution Analyzer. The results show that in contrast to ordinary cement mortar, if water to cement ratio (W/C) is constant, compressive strength of modified cement mortar can decrease, while flexural strength and toughness, ratio of compressive strength to flexural strength, increase with the increase of polymer to cement ratio in mass (P/C) at 7 and 28 curing days. With the increase of P/C, net structure made from polymer and cement hydration products is developed and pore whose size is smaller than 200Å begins to increase, which indicates pore diameters in modified cement mortar change to be finer. So microstructures of modified cement mortar become denser and display higher toughness.

Abstract: This paper presents a general numerical model to solve non-linear inverse heat conduction problems with multi-variables which include thermal parameters and boundary conditions, and can be identified singly or simultaneously. The direct problems are numerically modeled via FEM, facilitating to sensitivity analysis that is required in solving inverse problems via a least-square based CGM (Conjugate Gradient Method). Inhomogeneous distribution of parameters is considered, and a number of numerical examples are given to illustrate the work proposed.

Abstract: The evaluation of earth pressure is of vital importance for the design of various retaining walls and infrastructures. Experimental studies show that earth pressures are closely related to the mode and amount of wall displacement. In this paper, based on the reveal of the formation mechanism of earth pressures against rigid retaining wall with RTT mode, a new method is proposed to calculate the earth pressure distribution in such conditions. Finally, the effectiveness of the method is confirmed by the experimental results.

Abstract: The long spiral CFG pile construction often causes crack while in saturated slit. 3D finite element model is carried out, and the deformation of drilling hole is analyzed. The deformation’s factors are emphtically discussed such as drilling depth, dumped-soil load, soil strength, groundwater level etc. The results show that uneven settlement and horizontal displacement are relatively small while silt has high strength. The reduced soil strength is the main factor of drilling holes’ deformation, which causes serious hole shrinkage and the soil is brought to surface with spiral blade, and then causes “excessive dumping” and soil cracking.

Abstract: This paper used the method of spread the broken glass and light-colored stone into the asphalt mixture, then rolling to compact, to increase the brightness of the asphalt pavement in highway tunnel. Through a series of tests, we have studied the performance of the light-colored asphalt pavement, including high temperature stability, anti-sliding performance, impermeability, bond performance and the light-colored performance. Experimental studies have shown that the anti-sliding performance, high temperature stability will be lower slightly compared to ordinary asphalt concrete. Its impermeability has increased. The light-colored performance is better. At the same time, after the analysis of the experimental results we know that the improvement of light-colored performance is not only effected by the dosage of the materials, but also has a great relationship with the particle size. In general, the smaller the particle size of the materials joined, the more apparent the light-colored performance improved.

Abstract: In order to predict the permanent deformation of graded gravel, through to the existing flexible pavement granular base permanent deformation estimate model's contrastive analysis, combined with repeated dynamic triaxial test , selects Wei Mi permanent deformation estimate model as the loose aggregate permanent deformation of the estimate model, using 1stopt statistical analysis software carries on the nonlinear curve fit for the parameter, obtained two kinds of norms of graded broken stone aggregates forecast model of the correlation among the types : permanent deformation of the coefficient and water content and resilient modulus, and their reliability was analyzed. Analysis result shows that when load acting time reaches 10 000, the minimum and average correlative coefficients of the regression formulas is 0.4144 ,0.6340 and 0.5080, which is greater than the critical value of 0.3993, and the correlative coefficient between theoretical curve and measured one is more than 0.96. So the reliability of the proposed prediction formulas of permanent deformation for graded gravel is higher, can be used to forecast China's Asphalt Pavement Rutting.