A Study of the Suitable Measurement Location and Metrics for Assessing the Vibration Source Strength Based on the Field-Testing Data of Nanchang Underground Railway

Underground railway vibration source strength is one of the key values used for environmental impact assessment and the evaluation of mitigation measure’s performance.However,currently there is no international standard of measuring the underground railway vibration source strength for such purposes.The available local standards and industrial guidelines do not agree on measurement locations as well as the metrics for presenting the source strength.This has caused many confusions.This paper aims to study the suitable measurement location and metrics using the data from a large scale field-testing carried out at the Nanchang underground railway(Metro Line 1,China)in 2017.200 passing trains were recorded during the test at two different sections of the railway line,one with the spring floating slab installed and the other without.Three locations were chosen at each section,including one in the middle of the track and two on the tunnel wall at different heights.Based on the results of statistical analysis,the maximum of z-weighted vertical vibration level(VLzmax)obtained at a lower measurement location on the tunnel wall is the best for representing the underground railway vibration source strength,which is 76.66 dB obtained from this study.

Improved method for nondestructive measurement of dynamic pollen source strength from transgenic crops using sonic anemometer

Pollen-mediated gene flow from transgenic crops is a concern of the scientific community as well as the general public.Current lack is a nondestructive method to measure dynamic(hourly or shorter time period)source pollen release rate(source strength)from these crops.This paper reports an improved method using Rotorod concentration samplers and sticky slides,together with a fast response sonic anemometer,for measuring source strength from transgenic corn crops.Field measurements were made during the pollination season of 2001 at the Agronomy Research Farm,University of Connecticut,Storrs,Connecticut.Data were analyzed and used to estimate the pollen source strength of the corn crops at hourly time steps by considering both atmospheric transport and gravitational deposition processes.Details of the calculation and assumptions of the method are provided.Results from this study demonstrate that this method is sufficiently robust for use in estimating pollen source strength of transgenic crops with heavy pollen grains in assessing gene flow risks associated with field production of transgenic crops.

Effect of waste concrete with different strength on mechanical properties of recycled fine aggregate mortar

The influence of source concrete (SC) with different compression strengths on the workability and mechanical properties of recycled mortar made with river sand substituted by 100% fine recycled concrete aggregates (FRCA) is experimentally investigated. The basic physical performance test shows that with the increase in SC strength, FRCA exhibit lower water absorption and crushing index, meanwhile keeping higher densities. Mechanical property tests, including compressive strength, flexural strength and uniaxial compressive stress-strain tests, show that compressive strength,flexural strength and elasticity modulus of recycled sand mortars increase roughly with the increase in SC strength. The proposed mixture design method demonstrates that all of the components can be kept as the same as those in natural mortar mixture design and FRCA must be pre-wetted before making mortar mixture. Meanwhile, the reuse of higher strength SC can ensure that recycled mortar mixtures are able to achieve similar mechanical performance when compared to natural mortar designs.