【国外标准】 Standard Practice for (Analytical Procedure) Determining Transmissivity and Storage Coefficient of Confined Nonleaky or Leaky Aquifer by Constant Drawdown Method in Flowing Well

5.1 Assumptions—Leaky Aquifer: 5.1.1 Drawdown (sW) in the control well is constant,5.1.2 Well is infinitesimal diameter and fully penetrates aquifer,5.1.3 The aquifer is homogeneous, isotropic, and areally extensive, and5.1.4 The control well is 100 % efficient.5.2 Assumptions—Nonleaky Aquifer: 5.2.1 Drawdown (sW) in the control well is constant,5.2.2 Well is infinitesimal diameter and fully penetrates aquifer,5.2.3 The aquifer is homogeneous, isotropic, and areally extensive,5.2.4 Discharge from the well is derived exclusively from storage in the nonleaky aquifer, and5.2.5 The control well is 100 % efficient.5.3 Implications of Assumptions: 5.3.1 The assumptions are applicable to confined aquifers and fully penetrating control wells. However, this practice may be applied to partially penetrating wells where the method may provide an estimate of hydraulic conductivity for the aquifer adjacent to the open interval of the well if the horizontal hydraulic conductivity is significantly greater than the vertical hydraulic conductivity.5.3.2 Values obtained for storage coefficient are less reliable than the values calculated for transmissivity. Storage coefficient values calculated from control well data are not reliable.NOTE 7: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.1.1 This practice covers an analytical solution for determining transmissivity and storage coefficient of a leaky or nonleaky confined aquifer. It is used to analyze data on the flow rate from a control well while a constant head is maintained in the well.1.2 This analytical procedure is used in conjunction with the field procedure in Practice D5786.1.3 Limitations—The limitations of this technique for the determination of hydraulic properties of aquifers are primarily related to the correspondence between field situation and the simplifying assumption of the solution.1.4 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values in each system may not be exact equivalents; therefore each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this practice.1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.1.6 This practice offers a set of instructions for performing one or more specific operations. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of the practice may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without the consideration of a project’s many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.