Slope Stability Monitoring
Objective
Detect the onset of slope movement before failure, identify the shear surface, and quantify the rate of movement to inform early-warning and remediation.
Comprehensive Chapter References from Reference Manuals
| Chapter |
Title |
Application to Slope Stability |
| Ch 1 |
Geotechnical Instrumentation: An Overview |
Importance of slope monitoring, failure consequences |
| Ch 2 |
Behavior of Soil and Rock |
Shear strength, failure mechanisms, soil/rock behavior |
| Ch 3 |
Benefits of Using Geotechnical Instrumentation |
Early warning, design verification, legal protection |
| Ch 4 |
Systematic Approach to Planning Monitoring Programs |
20-step planning process specific to slopes |
| Ch 9 |
Measurement of Groundwater Pressure |
Piezometers for pore pressure triggering failure |
| Ch 12 |
Measurement of Deformation |
Inclinometers, extensometers, tiltmeters, settlement systems |
| Ch 17 |
Installation of Instruments |
Drilling, grouting, casing installation in slopes |
| Ch 18 |
Collection, Processing, Presentation, Interpretation |
Data collection frequency, automated systems, interpretation |
| Ch 19 |
Braced Excavations |
Strut loads, wall deflection, ground movement, groundwater |
| Ch 22 |
Excavated and Natural Slopes |
Primary chapter for slopes — inclinometers, piezometers, tiltmeters, surface survey |
From Foundation Engineering: A Public-Domain Reference (USACE / FHWA)
| Chapter |
Title |
Application |
| Ch 13 |
Slope Stability |
Infinite/finite slopes, method of slices, factor of safety |
| Ch 10 |
Lateral Earth Pressure |
Rankine/Coulomb, active/passive pressures on slopes |
| Ch 11 |
Retaining Walls & MSE Walls |
Stabilizing structures at slope toes |
| Ch 12 |
Sheet Pile Walls & Braced Excavations |
Excavation support on slopes |
From Soil Mechanics & Geotechnical Engineering: A Public-Domain Reference (USACE / FHWA)
| Chapter |
Title |
Application |
| Ch 6 |
Seepage & Flow Nets |
Seepage forces, slope drainage |
| Ch 7 |
Effective Stress & Pore Pressure |
Pore pressure effects on effective stress |
| Ch 10 |
Shear Strength |
Mohr-Coulomb, triaxial tests, CU/CD, pore pressure parameters |
| Ch 13 |
Problem Soils |
Expansive and collapsible soils on slopes |
Typical Instrument Array for Slope Stability
| Instrument |
Purpose |
Dunnicliff Chapter |
Representative Instrument |
| In-place inclinometer (IPI) array |
Continuous profile of lateral movement |
Ch 12, 22 |
MEMS IPI, wireless IPI |
| Vibrating-wire piezometers |
Pore water pressure triggering failure |
Ch 9, 22 |
VW piezometers, wireless piezometer nodes |
| Surface tiltmeters |
Catch the upper edge of a moving mass |
Ch 12, 22 |
MEMS tiltmeters, wireless tilt arrays |
| Surface survey points / GPS |
Surface displacement monitoring |
Ch 12, 22 |
Locator One GNSS, wireless mesh radio |
| Crackmeters / jointmeters |
Discrete crack/joint opening |
Ch 12 |
Crackmeters, jointmeters |
| wireless mesh radio |
Brings sensor data back to alert gateway |
Ch 8, 18 |
wireless mesh radio |
Installation Guidelines (from Dunnicliff Ch 9, 12, 17, 22)
Inclinometer Installation
- Casing: ABS or aluminum, grooved (4-groove standard)
- Grouting: Cement-bentonite grout, tremie method
- Initial readings: Establish baseline within 24 hrs
- Reading frequency: Daily (construction), weekly (monitoring), monthly (long-term)
Piezometer Installation
- Filter tip: Saturated, compatible with formation
- Seal: Bentonite above/below filter zone
- Saturation: VW piezometers per Ch 9 procedure
- Cable routing: Protected, strain-relieved
Tiltmeter Installation
- Mount: Stable concrete pad or bedrock
- Orientation: Perpendicular to anticipated movement
- Temperature compensation: Required for MEMS
Data Interpretation Guidelines (from Dunnicliff Ch 18, 22)
| Parameter |
Threshold/Action Level |
Reference |
| Inclinometer displacement rate |
> 5 mm/day = alert; > 20 mm/day = evacuation |
Ch 22 |
| Pore pressure increase |
> 80% of design value = alert |
Ch 22 |
| Tilt rate |
> 0.1°/day = alert |
Ch 22 |
| Crackmeter opening rate |
> 1 mm/day = alert |
Ch 22 |
Related Pages
Source: Compiled from Dunnicliff (616 chunks), Foundation Engineering (USACE/FHWA, public domain), Soil Mechanics (USACE/FHWA, public domain), NCHRP Synthesis 89, and field reference manuals.
Featured Video & Practical Resources
Featured Technical Webinar (Measurand & Geotechnical Observations): ShapeArrays for Landslide Monitoring — Automated Real-time Subsurface Displacement & Early Warning Systems.
Complementary Practical Field Resources from RST Instruments & Measurand (Terra Insights)
- RST Instruments (@RSTgeotechnical): Inclinometer Casing Installation
Standard field procedure for installing inclinometer casing in boreholes for deep lateral displacement tracking.
- Measurand (@MeasurandVideos): SAAView 3D Analysis Software
Visualization and 3D vector tracking of active landslide slip surfaces and mass movement zones.