Applied Mechanics and Materials Vols. 644-650

Abstract: Calculation and discussion have been carried about relation between compression of bored piles shaft and settlement of pile top, and valuation of ξ as composition coefficient adopted in standard method and distribution pattern of compression settlement characteristic by static load test on overlength bored piles in loess area as well as test and analysis on load-settlement characteristic of pile top together with strain test data on piles shaft.

Abstract: Based on the theory of equivalent internal friction angle, the soil layers around the tunnel were equal to cohesionless homogeneous mass in this paper. On the basis of the Terzarghi unconsolidated mass theory, the local soil arching effect of the existing open trench tunnel which was located the side walls load was discussed under the ground asymmetric filling. Furthermore, when the backfill soil appeared the local soil arching effect, the critical embedded depth formula was given. Finally, it is concluded that both the size and distribution of the ground asymmetric filling load have influence on the local soil arching effect of the existing open trench tunnel.

Abstract: The effect of equivalent fluid and viscoelastic boundary form considering soil's effect on long span cable-stayed bridge dynamic characteristics are analyzed to consider the additional mass method. Through the analysis, some useful conclusions of considering the water after the dynamic characteristics of the structure change greatly, and with the increase of water depth, frequency gradually more and more small, decreased significantly are obtained. Considering the fluid, structure is not the same under static load internal force changes. The cable has little effect, but beam and tower impact significantly, such as the moment of the direction of Z increased by 272%, so, the action of the fluid must be considered.

Abstract: Based on reinforced earth retaining wall of green gabion which is built at the site of seventh project Shaoxing-Zhuji Expressway, the research for soil pressure in a cross section which locate at the site of K38+398kmare made by field test and numerical analysis. The horizontal and vertical earth pressure are studied in the construction, The pressures between field test and numerical analysis which depend on FLAC^3D are rough similar. With increased of height in filling soil, the earth pressures on the wall toe in 3 direction such as horizon , vertical, 45°are increased ,and then gradually come to stability after construction. With increased of height in filling soil, the vertical earth pressures is increased, but the distribution for earth pressure at the same height is non-uniform. The horizontal earth pressure on the back of wall surface increases fast at first then decreases a little, which is a single peak-shaped, it distributes along the wall height in non-linear form, the maximum occurs at 1/3H. The result between field test and numerical model are different, because the flexible wall surface has a great affection on unload.

Abstract: Aiming at the phenomenon that the fixed piers of the continuous beams have been damaged during the earthquakes, In this paper the seismic responses are carried on based on a four-span continuous beam, pot rubber bearing and laminated rubber bearing are selected, and corresponding finite element model is built. The results indicate that the distributions of the longitude seismic forces between the piers are more reasonable for the latter bearing, especially under the long period and near-fault seismic excitations. The possiblity of adopting the laminated rubber bearing on the seismic control on the continuous beam are discussed, and the results can be referrd by the same bridges during designing.

Abstract: Stress variation is complicate during the course of rigid frame bridge construction, it is difficult to grasp the development trend of stress because of too many influencing factors. When using GM(1,1) model solely, the prediction accuracy is low and it is critical to collect much raw data of stress. Method of moving average improves GM(1,1) model by processing data before modeling. The paper takes Hu Lu-ding Bridge as an example and the results show that the GM(1,1) model established by moving-average method has higher prediction accuracy and can be efficiently used in stress prediction of rigid frame bridge.

Abstract: There are few studies about the shear lag effect and the effective flange width of the PC (Prestressed Concrete) box girder bridge with corrugated steel webs throughout the world in current time. In the present paper, based on the three-dimensional finite element analysis for a long-span continuous PC box girder bridge with corrugated steel webs and the corresponding conventional box girder bridge with concrete webs, a comparative study on the shear lag effect under vertical loads are carryied out together with the analyslis on the coefficient of the effective flange width. The results show that in the PC box girder with corrugated steel webs, the transverse distributions of longitudinal normal stress on the section of the slabs are obviousely non-uniform and they are different with those in the conventional PC box girder with concrete webs. And moreover, the shear lag effects in top slab of the PC box girder with corrugated steel webs are almost less obvious than those of the conventional PC box girder with concrete webs. However, the shear lag effects in bottom slab of the PC box girder with corrugated steel webs are almost similar to those of the conventional PC box girder with concrete webs, no matter what kind of vertical bending moment the cross section is subjected to

Abstract: The cable is the important force component of the cable-stayed bridges. The primary damage of cable is the corrosion which cause cable fracture. Local cable breaking lead to bridge force redistribution and have a certain impact to the mechanical characteristics of cable-stayed bridge, which affects the safety of bridge. The finite element model of cable-stayed bridge laboratory model is set up to simulate cable breaking and analyse the structure performance changes. At the same time carry out the corresponding cable breaking experiments. The conclusions through the theoretical and experimental analysis will provide a theoretical basis for the bridge health monitoring and bridge safety operation.

Abstract: With the development of the global oil industry,the production of the normal or high permeability reservoirs decline rapidly. Therefore, more and more low permeability reservoirs are used to the production stimulation. The oilfields overseas make great contribution to CNPC. The HF oilfield is one oilfield that the CNPC have in overseas. The HF oilfield is mainly the low permeability carbonate reservoirs which make it not easy to economically exploit. Due to the reason that the low permeability carbonate reservoirs present small porosity and the fluid’s flow situation in the low permeability carbonate reservoirs, the flow doesn't obey the Darcy's law. Thus it is greatly necessary to study the non-Darcy percolation characteristics. In this paper, the HF ‘s low permeability is tested and the threshold pressure gradient test is finished ,according to the experiment results, the nonlinear percolation ‘s law ,which is suited to HF-oil field , is illustrated and the reservoir classification is achieved.

Abstract: To be the result of assessment of the low permeability sandstone reservoir more objective, the new method-- entropy-weighting AHM, and six parameters which reflect the macroscopic properties, micro-structural characteristics and Oil-bearing property: Porosity, permeability, oil saturation, saturation in the value of pressure, back efficiency and clay content of mercury, have been selected to divide flow units of Sanjianfang reservoir in Qiuling oilfield. Reservoir flow units of the research area can be divided into I, II, III3-type reservoirs. The research indicated thatI, II, III3-type reservoirs are always located in different faces positions, and its physical property and oil-bearing properties decrease successively; Evaluation results are well consistent with the actual production of gas and oil. The entropy-weighting AHM method offers a new way for the division and evaluation of reservoir, which is a simple mathematic model with easy operation, but without consistency test and be adjusted to determine the matrix ,and the result of evaluation not only embodies the science, without losing the subjectivity . Hence it offers a brand new way for the evaluation of reservoir because of getting a good assessment result for the multifactor and multi-hierarchy complicated problems.