Method for quantitatively determining fractured rock mass permeability anisotropy

Abstract

The invention discloses a method for quantitatively determining fractured rock mass permeability anisotropy. The method comprises the following steps that a practical fractured rock mass is simulated, and similar materials which are different in inclination angle with the horizontal direction are prepared; the permeability rates of the similar materials with different inclination angles are measured, and a function relational expression of the permeability rates and the inclination angles is determined; derivation is conducted on the function relational expression, a derived function of the function relational expression is obtained, and the derived function shows the change rate of the permeability rates to the inclination angles; standardization processing is conducted on the derived function, a relational expression of unit permeability rate change quantity caused by unit inclination angle change to the inclination angles is obtained, and the relational expression is a quantitative expression of the permeability anisotropy of the practical fractured rock mass to be measured. According to the method for quantitatively determining the fractured rock mass permeability anisotropy, a mathematical analysis method is used for determining the change rate of the permeability rates of the fractured rock mass in different directions, standardization processing is conducted on the change rates of the permeability rates and the inclination angles, the unit permeability rate change quantities caused by unit inclination angle change at different inclination angles are obtained, and the permeability anisotropy of the fractured rock mass with larger permeability rate differences can be accurately expressed.

Description

technical field [0001] The invention relates to a method for determining the permeability properties of fractured rock mass, in particular to a method for quantitatively determining the seepage anisotropy of fractured rock mass. Background technique [0002] After a long period of geological transformation and supergene evolution, the rock mass in a certain geological stress environment has widely developed joints, bedding, contact zones, shear zones, faults and other structural planes, so in practice Most of the rock mass encountered in the project is a fractured rock mass composed of structural planes and complete rock blocks. Due to the existence of complex discontinuous structural planes in the fractured rock mass, the permeability of the fractured rock mass is higher than that of ordinary homogeneous rock mass. The permeability properties of , continuous, and isotropic materials are much more complex, showing significant permeability anisotropy, which has a significant ...

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Problems solved by technology

[0003] Although the seepage anisotropy of the fractured rock mass has a significant impact on the seepage properties of the rock mass and engineering safety, there are few studies on the seepage anisotropy of the fractured rock mass at present, because the fractured rock mass generally contains many Due to the limitation of field conditions, test equipment and test cost, it is very difficult or even impossible to measure the permeability anisotropy of fractured rock mass by in-situ test. test method measurement

However, the natural rock samples taken according to the size of laboratory test samples usually contain only one group or no fractures, which cannot fully reflect the permeability anisotropy of the rock mass, and the fractured rock mass has geometric variability. The difference is large, the test results of natural rock samples taken from some rock masses are not fully representative, and there is currently no effective method for quantitatively determining the permeability anisotropy of fractured rock mass

[0004] The Chinese invention patent application with the application number 201410604481.7 "A Quantitative Prediction Method for Permeability Tensor and Anisotropy of Fractured Reservoirs" proposes a method that expresses the ratio of the maximum and minimum values ​​of permeability in different directions of fractured rock mass However, this method can only reflect the difference in the maximum value of permeability in different directions of the fractured rock mass, and cannot reflect the difference in permeability in other directions of the fractured rock mass, and the value of the obtained permeability anisotropy is not sufficient. representative, so there is an urgent need for an effective method to quantitatively determine the permeability anisotropy of fractured rock mass

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