Advanced Materials Research Vols. 1030-1032

Abstract: Results obtained from in-situ load tests carried out on omega displacement piles sunk in a porous, lateritic and unsaturated soil deposit, are analyzed in this paper. Three slow-maintained load tests were performed on deep instrumented piles with a diameter of 0.37 m and around 12 m long. The soil deposit consists of a superficial, silty clay “porous” layer 6 m thick. Under this layer there is a lateritic stratum 10 m thick, geotechnically consisting of a residual clayey silt. The results of the field load tests yielded a maximum pile load (average for the tests) of 1428 kN, which is twice as high as corresponding experimental values from standard bored piles with similar geometric conditions. Numerical finite element analyses, were performed in order to back-analyze the geotechnical soil parameters for a post-execution pile condition. The results permitted a better understanding of the improvement of the subsoil given the intrinsic execution characteristics of this particular pile. It was also possible to note that omega displacement piles have great potential to become an economically viable solution in tropical soils, given the enhanced behavior of such piles when compared to alternative techniques.

Abstract: The example which is selected in this engineering project is the hospital in Lanzhou University of Technology, the paper analyzed the reason that the foundation subsidence, and used reasonable and effective method on reinforcement. It hoped that the achievement can provide beneficial reference for handling the problem that foundation subsidence in collapsible loess areas.

Abstract: In HongKong-Zhuhai-Macao bridge project, about 4.8 kilometers stone bed underwater should be compacted to make it smooth and remove the excess settlement. Vibrating compaction method would be used to tamp the stone layer with no dead angle in a short construction period. This paper theoretical studied on vibrating compaction technology of scattering-filling rubble stone layer. Vibrating compaction system and stone layer were simplified to a mechanical model and the vibration equation was established. According to an interpolation table, a fitting formula of equivalent damping was given. Through rigorous mathematical derivation, this paper gave mathematical expressions of the vibration displacement, the vibration velocity and compaction work on stone layer. Both compaction work on land and compaction work underwater could be calculated by these mathematical expressions. Lastly, through a set of field test parameters, comparative analysis between compaction work on land and compaction work underwater was carried out. The result shows that the weakening effect of water on compaction work is poor.

Abstract: Abstract: The paper, by using various electrochemical methods, conducts non-destructive quantitative testing towards currently-used bridges, analyzes reinforcement corrosion characteristics under natural environment, concludes the influencing rule of natural environment on reinforcement corrosion, and reveals differences accelerated simulation environment by contrasting with preliminary laboratory results. The real bridge measurement results show that: weight loss ratio of reinforcement under humid environment can reach a maximum of 33% and a minimum of 18%; while weight loss ratio of reinforcement under dry environment falls between 8%-15%. The actual measurement results also show that: box girder and guard bar coated with waterproof layer help to protect reinforcing bars inside the concrete and effectively reduce the corrosion rate inside reinforcing bars with weight loss ratio around 4-8%. It contrasts the precision of two testing methods and comes to a conclusion that testing precision of linear polarization method is higher than that of impulse current method.

Abstract: Accurate simulation of construction process of continuous rigid frame bridge is a foundation to make a bridge built accurately. Based on the suit iteration method, this paper used MIDAS to built a 3D finite elements model, the internal force and deformation results of each construction stage was obtained. This study provided a good theoretical reference for the control of long-span continuous rigid frame bridge construction..

Abstract: The effect of pavement roughness on the roadbed and retaining structure underground was studied. Three different groups of International Roughness Index (IRI) were analyzed based on 6221 data collection instrument in this paper. Results show that different pavement roughness has different effect on retaining structure. Additionally, the vibration RMS increases with IRI when it is in the range of normal driving for the car, but amplitude of the IRI is larger. Finally, the main factors which influence the stability of structure and some corresponding improving measures are presented.

Abstract: In this paper, adding multiwalled carbon nanotubes (MWCNTs) to the polymethylmethacrylate-based (PMMA) bone cements as a way of reinforcement were prepared, and the structure was investigated. The aim of this study was to confirmed the transverse-direction fracture toughness (K_Iv) in bone cement. The K_Iv of PMMA cement and PMMA/MWNCTs cement were determined to be 1.32±0.1 MPa m^1/2 and 1.96±0.1 MPa m^1/2, respectively.

Abstract: Yihe River No. 2 extra large bridge is taken as an example in this paper, from the establishment of control network, the pile foundation to the lofting of caps and other structures, this paper introduces the measurement methods used in the extra large bridge construction process, and how to assure the accuracy of bridge construction in the measurement as well, which provides reference for similar projects.

Abstract: In this paper,a general dynamic model of the isolation coupled system which is composed of isolation object,nonlinear vibration isolation support,and flexible foundation is established,calculated method of applying vibration power flow to analyze isolation effectiveness is studied.Further more,as an calculation example,a air spring vibration isolation system of HS-700 engines is numerically simulated.Designs several low-frequency nonlinear vibration isolators and analyzes its vibration isolation effect.It discusses the effect of the vibration isolator parameters on the transmitted power flow of the system.The results provide a theoretical basis for the optimized design of nonlinear vibration isolation system.

Abstract: The impact ductility of plain concrete and polymer-modified concrete with different p-c (polymer-cement) ratio were measured by bend-impact method. The impact-resistance of plain concrete and polymer-modified concrete were contrasted. The modified mechanism of polymer-modified concrete was analyzed. The results indicate that the impact ductility of concrete are increased with contents of polymer firstly and then reduced and the best p-c ratio is 15%. The test results also indicate that the concrete performance are modified by polymer, which prevent crack developing in microcosmic and improve impact ductility in macroscopic.