Applied Mechanics and Materials Vols. 303-306

Abstract: This paper test sound absorption coefficient of different air voids specimen in reverberation chamber and low noise pavement field testing, which gets main frequency band range of pavement noise is 315~5000Hz, noise arrives at the peak of about 500Hz; the relationship of microphone height and sound pressure level is not obvious; the porous asphalt mixture which air voids is more than 20% has the upper sound absorption coefficient at the frequency of 400~1000Hz, and its noise reduction effect is obvious; There is a linear relationship between the air voids and the maximum absorption coefficient of asphalt mixture, increasing air voids can cause larger absorption coefficient; sound-absorbing property of the low noise asphalt pavement is one of the dominant mechanism of mitigation traffic noise.

Abstract: Lishi loess is an important component of loess slope. To explore the structure and strength change characteristics of Lishi loess caused by shock (vibration) action, and to reveal the mechanism of loess slope catastrophe, the dynamic triaxial test was performed by using equivalent sine wave under strain controlling. The results show that:① There is an obvious stress relaxation phenomenon during the same cyclic loading test, the degree decreases with the increasing of dynamic strain and confining pressure. And the influence of dynamic strain variation on stress relaxation degree is less under high confining pressure than under low confining pressure;② Under a confining pressure of 40kPa, within 1% strain ranges, the needed dynamic stress to reach the specified strain is just 0.01kN, and the peak stress decreases with the augmentation of dynamic strain, when peak stress increases to 0.204kN, the sample is destructed; Under a confining pressure of 90kPa, soil radial particles are closely spaced, within 2% strain ranges also only a dynamic stress of 0.01kN is needed to reach the specified strain, and with the increase of dynamic strain, the samples are destructed when dynamic strain increases to 0.267kN. The dynamic failure stress of Lishi loess increases gradually with the increase of confining pressure, and the linear regression equation is бd=0.0011б3+0.1590, the correlation coefficient is 0.9944. ③According to Mohr-Coulomb failure criterion, the strength parameters of Lishi loess in somewhere of the north of shaanxi are C=30.33kPa，φ=14°. Under the dynamic shearing action, the dynamic effective strength parameters are obviously less than static effective strength parameters, this indicates that the soil consolidation effect reduced and the particles displaced and occluded each other.

Abstract: In order to determine interlayer separation threshold and separation stability of complex roof, distribution of interlayer separation was analyzed in different conditions by a contact element method based on nonlinear contact theory in ANSYS program. The conclusion was drawn that normal stress was tension stress in the center of construction surface in deep mining and it could be considered as interlayer separation threshold of complex roof.

Abstract: As an important force part of the Bridge, the precise positioning of the construction of anchorage system is especially important. Combining with the practice of bridge engineering, this paper introduces the precise positioning of anchorage system by two-point reference line lofting principle. The results have proved that all the deviations satisfy the requirements of regulation by reference line lofting. This method decreases the cost, increases the measuring accuracy. It is worth wide spreading.

Abstract: Theoretical analysis and finite element numerical simulation are done to calculateputing force and displacement under different closure orders of mid-span and side span. Furthermore, stress, horizontal displacement and deflection of bridge structure are analyzed. Closure scheme that construction mid-span firstly, then side span according to calculated launching force is proposed and discussed. Obvious advantage of the new scheme is construction with hanging basket and guiding beam instead of supporting frame. And the measures are simple, safe and reliable.