Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D4395-17 – Standard Test Method Technical Guide
📏 Scope and Application of D4395-17
ASTM D4395-17 provides a standardized methodology for determining the in situ modulus of deformation of a rock mass using the flexible plate loading method. This standard is specifically intended for execution in an adit or small underground chamber, although it can be adapted for surface use. The orientation of the loading test is typically conducted parallel or perpendicular to the anticipated axis of thrust dictated by the design load.
The test method yields both instantaneous deformation and primary creep properties of the rock mass. All results must comply with the significant digit guidelines established in Practice D6026. It is important to note that the values stated in inch-pound units are regarded as standard; SI units provided in parentheses are mathematical conversions for information only.
🔬 Key Scope Note: Time-dependent tests not explicitly covered by this standard (beyond primary creep) are permitted but must be reported under a separate standard protocol.
⚙️ Test Procedure, Equipment, and Setup
The apparatus involves a flexible plate system, usually a flat jack or hydraulic bladder, pressed against a prepared rock surface to apply uniform pressure. Deformation of the rock is measured using an extensometer system, which must conform to the specifications of Practice D4403. The load is applied in a series of cycles, and the resulting displacement is plotted against pressure.
| 🟦 Parameter | 📏 Specification / Requirement |
|---|---|
| Loading Type | Flexible Plate (Hydraulic Jack) |
| Test Environment | Adit or Small Underground Chamber |
| Test Orientation | Parallel or Perpendicular to Axis of Thrust |
| Measured Deformations | Instantaneous Deformation & Primary Creep |
| Standard Reporting Units | Inch-Pound (SI provided for reference) |
⚠️ Safety & Compliance: Section 8 of the standard outlines specific precautionary statements for field operations. Agencies performing this testing should adhere to the minimum requirements in Practice D3740 for soil and rock testing.
📊 Key Measured Properties and Data Reduction
The primary property derived from this test is the in-situ modulus of deformation. Data reduction focuses on the pressure-deformation curves. The standard mandates full compliance with Practice D6026 for significant digits and rounding. The user of the standard is responsible for applying the results appropriately in design, as the data collection specifics are not directly tied to design accuracy limits.
Supplementary ASTM standards heavily interface with D4395 for comprehensive characterization:
| 📐 Standard | 🎯 Purpose in D4395 Testing |
|---|---|
| D653 | Standard Terminology for Soil, Rock, and Contained Fluids |
| D2113 | Rock Core Drilling and Sampling for Site Exploration |
| D4403 | Standard Practice for Extensometers Used in Rock |
| D4394 | Rigid Plate Loading Method (Flexible Plate Alternative) |
| D6026 | Significant Digits and Rounding in Geotechnical Data |
✅ Best Practice: Conducting both D4395 (Flexible Plate) and D4394 (Rigid Plate) tests allows for a comprehensive comparison of rock mass behavior under different boundary loading conditions, providing a robust dataset for design inputs.
❓ Frequently Asked Questions
🔍 What is the primary purpose of ASTM D4395-17?
To determine the in situ modulus of deformation of a rock mass using the flexible plate loading method. It provides a mechanical property essential for analyzing rock mass stability and foundation design.
💡 Where is this test method designed to be conducted?
It is designed specifically for use in an adit or small underground chamber, aligned either parallel or perpendicular to the anticipated axis of thrust. It can be modified for surface work.
⚡ What types of deformation can be extracted from the data?
The test procedure captures both instantaneous deformation and primary creep, allowing for an elastic and time-dependent analysis of the rock mass behavior under load.
📌 Which standard governs the reporting of significant digits?
All observed and calculated values must conform to the guidelines for significant digits and rounding established in Practice D6026.
📏 What are the standard reporting units for D4395-17?
Values stated in inch-pound units are regarded as the standard. Values in parentheses are mathematical conversions to SI units provided for information only.