Test method for saturated permeability coefficient of constant head water injection test in boreholes in vadose zone

Abstract

The present invention relates to test technology of a saturated infiltration coefficient of rock and soil of a vadose zone, and a test method for the saturated infiltration coefficient of a drilling constant water head water injection test of the vadose zone is provided on the basis of the effect of the vadose zone infiltration on well hole water infiltration laws. The test method comprises the following steps: the first step, preparing for the test, determining test points and drilling; the second step, determining rock and soil properties and unsaturated infiltration characteristic values; the third step, performing the water injection test, and recording test data; and the fourth step, systemizing the data, and calculating the saturated infiltration coefficient. The method considers the influence of the rock and soil unsaturated infiltration characteristics on well hole infiltration, test results are more accurate; a design calculation table of infiltration coefficients under different pore sizes and soil properties is given, the saturated infiltration coefficient is more convenient to calculate, and the work efficiency is manyfold improved.

Description

technical field [0001] The invention relates to a technique for testing the saturated permeability coefficient of rock and soil in the vadose zone. Based on the effect of the permeability characteristics of the vadose zone on the infiltration law of wellbore water, a test method for the saturated permeability coefficient of the constant water head water injection test in the borehole of the vadose zone is proposed. Background technique [0002] The saturated permeability coefficient is an index that comprehensively reflects the seepage capacity of rock and soil, and the accurate determination of its value is of great significance to the calculation of seepage of water in rock and soil. There are many factors that affect the saturated permeability coefficient, such as the shape, size, uneven coefficient of rock and soil particles, and water viscosity. It is difficult to establish an accurate theoretical formula for calculating the saturated permeability coefficient. Experiment...

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Problems solved by technology

"Procedure 1" provides a test method for the saturated permeability coefficient of the borehole dewatering head water injection test in the vadose zone, but because the calculation formula and influencing conditions are very complicated, the general application is seldom at present and it is in the stage of research and accumulation of data

"Procedure 2" formed on the basis of "Procedure 1" revised the method to a borehole constant head water injection test, and gave the calculation formula and applicable conditions of the saturated permeability coefficient. However, Zhang Yihuo's article "Drilling Water Injection Analysis of test methods” (Journal of Resources, Environment and Engineering, 2008, 22 (10)), Sheng Lin’s article “Effects of Different Heads on the Conductivity Coefficient in Constant Head Water Injection Test” (Journal of Small Hydropower, 2015 (02) ) research found that the calculation formula of the saturated permeability coefficient and applicable conditions of the revised test method have relatively large limitations, and there are even contradictions, and the application is very inconvenient

Therefore, at present, there is a lack of accurate and reliable in-situ testing technology for saturated permeability coefficient for rock and soil in the vadose zone, especially for deep rock and soil.

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