Measuring method of anisotropy coefficient of transverse isotropic rock in-situ dynamic elasticity modulus

Abstract

The invention relates to a measuring method of anisotropy coefficient of transverse isotropic rock in-situ dynamic elasticity modulus. In the measuring method, a first testing hole, a second testing hole, and a third testing hole are parallelly arranged on a flat plane of a transverse isotropic rock, wherein the orifices of the first testing hole, the second testing hole, and the third testing hole are all in an equilateral triangle shape. The axial dip angels of each testing hole are determined by whether the inclined angle between the isotropic surface of the transverse isotropic rock and the horizontal plane is greater than 45 degrees or not. The measuring method comprises: carrying out an ultrasonic wave longitudinal wave measurement on each testing hole through single-hole measurement mode; carrying out ultrasonic longitudinal penetration tests between any two holes in a hole-to-hole penetrating testing mode, and finally processing, calculating, and analyzing the measured wave speed data so as to obtain the anisotropy coefficient of transverse isotropic rock in-situ dynamic elasticity modulus. The provided measuring method has the advantages that the disturbance on the transverse isotropic rock is small and the measured anisotropy coefficient of transverse isotropic rock in-situ dynamic elasticity modulus is precise.

Description

technical field [0001] The invention relates to a method for testing the in-situ anisotropy coefficient of rock mass, and more particularly to a method for testing the in-situ dynamic elastic modulus anisotropy coefficient of engineering rock mass with transverse isotropic characteristics. The anisotropy coefficient of the in-situ dynamic elastic modulus of the transversely isotropic rock mass can be effectively obtained by drilling test holes and using ultrasonic testing equipment under in-situ conditions in the field. Background technique [0002] On the earth's surface, about 70% of the rocks are sedimentary rocks, plus some other metamorphic rocks and volcanic rocks with layered or bedded structures. Most of the engineering rock masses faced by human engineering construction activities are transversely isotropic or A rock mass that is approximately transversely isotropic. Engineering practices such as highway tunnel excavation, urban subway excavation, and mine slope re...

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Problems solved by technology

[0004] However, due to the complex field environment of engineering rock mass and its complex joint-rock composite structure characteristics, the existing ultrasonic testing technology reserves for transversely isotropic rock mass or anisotropic properties of rock are insufficient. Several ultrasonic testing methods or test methods involving the anisotropic properties of transversely isotropic rock mass or rocks are either too complicated, or the measurement results cannot accurately reflect the field in-situ state of transversely isotropic rock mass:

[0005] (1) Generally, some rock anisotropy acoustic wave testing methods are basically aimed at rock samples under laboratory conditions or cores separated from in-situ rock mass, which cannot fully reflect the structural planes contained in in-situ engineering rock mass. The objective existence of the in-situ rock mass cannot reflect the in-situ stress environment of the in-situ rock mass, so the anisotropy coefficient of the rock mass obtained by its measurement cannot accurately represent the truest situation of the in-situ rock mass

"Journal of Chongqing University of Civil Engineering and Architecture", No. 6, 2007, titled "Study on Ultrasonic Testing Experiment of Anisotropic Rock Mass", author Tu Zhongren, the research took the Xiamen Submarine Tunnel as the engineering background, and carried out indoor acoustic testing on the collected rock blocks work, to study the influence of internal cracks and rock sample compactness on acoustic parameters, but failed to give its anisotropy coefficient; "Sichuan Hydropower", No. 2, 2009, titled "Sand and slate Research on anisotropy”, the author Zhao Yongjin, this study studied the wave velocity characteristics of sandstone and deformation in the direction perpendicular to and parallel to the isotropic plane through indoor acoustic wave testing, based on which the anisotropy coefficient was proposed, but the test results were not consistent with The anisotropy coefficients obtained by other test methods are inconsistent, indicating that the reliability of the indoor test results is not high; This application establishes an electromechanical-acoustic network of sheet-shaped compressional wave transducers, and calculates the energy velocity measured in the direction of the energy angle for anisotropic rock samples to accurately obtain the P-wave phase velocity, but the The measurement method does not consider the behavior of the in-situ rock mass, so it is difficult to apply on-site

[0006] (2) The acoustic wave measurement method of formation properties of some logging methods is too complicated to be used flexibly in the field, or the parameters obtained only represent the differences between different formations or lithologies, and cannot be used for the parallel or vertical characteristics of the rock mass. Measurement between isotropic planes, so it is impossible to obtain reliable anisotropy characteristic coefficient of anisotropic rock mass

"Journal of Rock Mechanics and Engineering", No. 1, 2006, titled "Experimental Research on Evaluation of Formation Drillability Anisotropy by Acoustic Wave Method", author Pan Qifeng et al. The anisotropy coefficient of rock wave velocity is obtained from the sound wave velocity parallel to the formation layer, which provides a reference for drillability, but the test object does not include the core of the in-situ stress environment and structural plane, not the in-situ rock mass ; "Journal of Shengli College, China University of Petroleum", Issue 4, 2009, titled "Analysis of Rock Mechanical Properties and Formation Velocity Anisotropy—China Continental Scientific Drilling Well 1", author Zhai Yong et al. The orthogonal multipole sub-array acoustic logging tool combined with monopole technology can obtain the anisotropy of different formations, but the test results do not reflect the anisotropy of the same rock mass between its parallel isotropic plane and vertical isotropic plane. Anisotropy coefficient; "Sichuan Hydropower", No. 5, 2009, titled "Application of Single Hole Acoustic Wave Method in Testing Loose Circles of Rock Mass", author Hu Wenyi et al. This study introduced how the single hole acoustic wave method can understand the The stress state of the medium, the relaxation thickness of the cave wall rock mass, etc. are detected, but the anisotropy coefficient characteristics of the in-situ dynamic elastic modulus of the transversely isotropic medium are not considered in the test methods and test results.

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