Abstract
How to obtain dynamic parameters of rock masses quickly and precisely is a popular and difficult problem, which plays a very important part in engineering design or construction. Currently, the methods used to obtain these parameters are in situ testing method, empirical formula, and so on. However, these methods have some shortcomings, such as large investment and long construction period, which cannot obtain the dynamic parameters precisely and quickly in the engineering scale. In this study, a new method of estimating the rock parameters based on the measured field blasting vibration signals is proposed according to theory of elastic stress wave. In addition, an improved method for S-wave identification used in engineering scale was proposed and then the numerical simulation is given to verify the feasibility. Comparison of the numerical identification results and theoretical results clearly show that the improved method is available in S-wave identification with errors less than 2%. By identifying the arrival times of P and S waves, the propagation velocities of P and S waves are calculated and the parameters of rock mass can be obtained at last. Through analyzing the measured field blasting vibration signals in Fengning pumped-storage power station, the dynamic elastic modulus of rock mass inversed by vibration signals is about 2.2~2.9 times of its static elastic modulus, while the inversed dynamic Poisson's ratio is 0.9~0.975 times of the static.
Highlights
With the rapid development of society and economy in China, more and more hydropower stations are being built in the southwest and northwest area
By numerical simulation analysis and analyzing the measured vibration signals of Fengning pumped storage power station, the following conclusions can be drawn from this paper: (1) The S wave identification method in this study is based on the differences in polarization, vibration directions, and energy of P and S waves
By the numerical simulation, the S wave identification method is effective with errors less than 2%
Summary
With the rapid development of society and economy in China, more and more hydropower stations are being built in the southwest and northwest area. The determination of dynamic parameters of rock mass such as dynamic elastic modulus and dynamic Poisson's ratio in large scale is prerequisite of solving these dynamic problems. Obtaining reliable rock dynamic parameters quickly and efficiently has become a hotspot of study in the field of rock dynamics. Because of the importance of the rock mass dynamic parameters, various studies on the subject with different approaches have been conducted by many researchers. Some scholars studied the dynamic parameters in different loading rates by laboratory experiment [4]. Because of the scale effect of rock mass influenced by sample sizes, sample disturbance, and sampling conditions, the value of dynamic parameters obtained by laboratory tests cannot reflect the properties of rock mass. To obtain the parameters accurately, in situ testing was proposed by some scholars. To overcome the above shortcomings, many researchers have introduced ultrasonic wave test to estimate the mechanical
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