中国·永利y23455(股份)有限公司

EPC customised NMR Analyzer for Unsaturated Soils

Northwestern China's loess is a typical problematic soil with strong water sensitivity (e.g., wetting collapse). Its gas-containing structure makes measuring volume changes difficult, while pore water saturation determination is even harder. Most challenging is precisely controlling and uniformly distributing moisture content within the soil.

In unsaturated soils, a defined relationship exists between volumetric water content and matric suction, known as the soil-water characteristic curve (SWCC). Theoretically, each matric suction value corresponds to a specific water content during drying/wetting paths. While controlling matric suction regulates overall water content, verifying internal moisture uniformity remains challenging. Current methods rely on prolonged equilibrium periods, yet lack quantitative metrics for saturation homogeneity.

NMR Technology for Soil-Water Characterization
The NMR spectrometer serves as a powerful research tool for investigating water content in materials, enabling precise measurement of internal moisture distribution. This capability effortlessly resolves the longstanding challenge of verifying water content uniformity. Furthermore, NMR imaging provides 3D reconstruction of scanned objects, allowing straightforward visualization and accurate quantification of deformations and volumetric changes.

Current Limitations in Conventional NMR Testing
Standard NMR measurements are typically conducted on relaxed samples without stress simulation. While this approach may suffice for rigid materials like metals or dense rocks, it proves inadequate for stress-sensitive granular materials like soils. Performing NMR scans on stress-relieved soil samples yields limited practical value. Accurate characterization requires:

1. Precise simulation of in-situ stress conditions

2. Controlled regulation of internal water content
   Only through such controlled conditions can the actual soil-water characteristic behavior be determined across varying depths and stress states.

Specialized NMR Soil-Water Characteristic Curve (SWCC) Testing System
Our custom-engineered NMR imaging SWCC apparatus addresses these exact requirements:
• Integrated stress simulation (confining pressures/shear stresses)
• Controlled wetting/drying pathways
• NMR-compatible test chamber (custom-fitted to existing spectrometers)
• Advanced materials minimizing signal interference
This system generates 3D visualizations of porosity and moisture distribution across varying suction levels and volumetric water contents, enabling comprehensive analysis of evolving patterns under true stress conditions.

stress application

NMR results: varied WC & stages

Main Features of the Unsaturated Soil NMR Analyzer:

• Complete SWCC Acquisition – Obtains full drying and wetting soil-water characteristic curves from a single sample

• Compact Design – Fits inside the NMR instrument chamber (sample dimensions: 50mm diameter × 20mm height, including specialized NMR-compatible confinement ring)

• Precise Measurements – Accurately monitors total volume change and water content

• Matric Suction Control – Uses axis-translation technique (0–500 kPa range) with dual-precision pressure gauges and regulators

• Automatic Bubble Removal – Peristaltic pump flushes escaped bubbles from ceramic disks to improve accuracy

• Automated Water Volume Tracking – Electronic balance continuously records inflow/outflow, with computer data logging

• Integrated NMR Scanning – Performs high-resolution imaging at each suction equilibrium stage for clear moisture distribution visualization

 EPC customised Unsaturated Soil NMR Analyze product photo: