A comparison of tectonic ambient shear stress value in China with that in western USA

A method is proposed to estimate average tectonic ambient shear stress value for a region. Thus the average stress values of 19 regions in western USA, and 43 regions (each region is 1010) in Chinese mainland and its surroundings have been obtained. The data of 15 993 earthquakes are from the Internet Centroid Moment Tensor solution made by Harvard University from 1997 to 1999. The results demonstrate that there are highest average stress values in the regions of south California of USA and its off coast sea, reach to 12.0 MPa and 13.7 MPa respectively, then gradually decrease toward north, south, and east. The lowest value is 8.7 MPa and 63% of highest value. The average stress values in northern Xinjiang and in the Chayu region of Tibet are 17.2 and 12.9 MPa respectively. They are highest values in China and higher than USAs. The average stress value in North China, Yunnan, Sichuan, Taiwan is similar to south California of USA. The average stress value in South-North seismic zone is about 13 MPa, a little higher than south California. The distribution of average stress value for two important regions provides basic data for geology. These results are useful to research earthquake activity background and attenuation relation of strong ground motion parameters (e.g. peak acceleration and response spectra).

Performance of interface between TRC and existing concrete under a chloride dry-wet cycle environment

Textile-reinforced concrete(TRC)is suitable to repair and reinforce concrete structures in harsh environments.The performance of the interface between TRC and existing concrete is an important factor in determining the strengthening effect of TRC.In this paper,a double-sided shear test was performed to investigate the effects of the chloride dry-wet cycles on the average shear strength and slip at the interface between the TRC and existing concrete,also considering the existing concrete strength,bond length,textile layer and short-cut fiber arrangements.In addition,X-ray diffraction(XRD)technology was used to analyze the microscopic matter at the interface in the corrosive environment.The experimental results indicate that the interface performance between TRC and existing concrete would decrease with continued chloride dry-wet cycles.Compared with the specimen with a single layer of textile reinforcement,the specimens with two layers of textile with added PVA or AR-glass short-cut fibers could further improve the properties of the interface between the TRC layer and existing concrete.For the TRC with a single layer of textile,the average shear strength tended to decrease with increasing bond length.In addition,the strength grade of the existing concrete had a minor effect on the interface properties.

Study on Drag and Noise Reduction of Bionic Blade of Centrifugal Pump and Mechanism

In order to study the relationship between the important parameters of internal flow and the effect of drag and noise reduction,the internal flow field and sound field characteristics of bionic centrifugal pump are studied in this paper.Based on the methods of theoretical analysis,numerical simulation and test,the relationship between wall average shear stress,drag reduction rate,increasing efficiency and noise reduction rate of internal sound field is studied.Internal flow parameters to judge and predict the effect of drag and noise reduction are revealed.The results show that the bionic pit can effectively increase the thickness of the boundary layer and reduce the Reynolds stress on the wall.The resistance on the wall is reduced and the hydraulic efficiency of the centrifugal pump is increased.The noise reduction rate is basically consistent with the changing trend of the drag reduction rate,increasing efficiency and wall average shear stress in the flow field.Wall average shear stress can reveal the effect of drag and noise reduction,so the effect of drag and noise reduction can be predicted and judged by the change of wall average shear stress.