Foundation & Deep Excavation Monitoring
Objective
Verify design assumptions about load-settlement behavior, validate deep foundation capacity, and protect adjacent structures during deep excavation (heave, lateral movement).
Comprehensive Chapter References from Reference Manuals
| Chapter |
Title |
Application to Foundation/Excavation Monitoring |
| Ch 1 |
Geotechnical Instrumentation: An Overview |
Foundation/excavation monitoring importance |
| Ch 2 |
Behavior of Soil and Rock |
Soil behavior under loading, heave mechanisms |
| Ch 3 |
Benefits of Using Geotechnical Instrumentation |
Design verification, construction control, adjacent structure protection |
| Ch 4 |
Systematic Approach to Planning Monitoring Programs |
20-step planning for foundations/excavations |
| Ch 5 |
Specifications for Procurement of Instruments |
Foundation instrument specs |
| Ch 6 |
Contractual Arrangements |
Foundation/excavation contracts |
| Ch 8 |
Instrumentation Transducers & Data Acquisition |
Load cells, settlement systems, automated monitoring |
| Ch 9 |
Measurement of Groundwater Pressure |
Dewatering pressures, piezometers inside/outside excavation |
| Ch 12 |
Measurement of Deformation |
Primary — Settlement plates, extensometers, inclinometers |
| Ch 13 |
Measurement of Load and Strain |
Primary — Load cells, strain gages, telltales |
| Ch 14 |
Measurement of Temperature |
Concrete hydration, freeze-thaw |
| Ch 17 |
Installation of Instruments |
Installation in excavations, limited access |
| Ch 18 |
Collection, Processing, Presentation, Interpretation |
Real-time excavation monitoring |
| Ch 19 |
Braced Excavations |
Primary for deep excavations — strut loads, wall deflection, groundwater |
| Ch 20 |
Embankments on Soft Ground |
Soft ground foundations, ground improvement |
| Ch 24 |
Driven Piles |
Pile load tests, telltales, strain gages |
| Ch 25 |
Drilled Shafts |
Load tests, integrity, downdrag |
| Ch 26 |
The Key to Success |
25-link chain for foundation/excavation success |
From Foundation Engineering: A Public-Domain Reference (USACE / FHWA)
| Chapter |
Title |
Application |
| Ch 2 |
Subsurface Exploration & Site Characterization |
Site investigation for foundations |
| Ch 3 |
Shallow Foundations: Bearing Capacity |
Bearing capacity theories |
| Ch 4 |
Shallow Foundations: Settlement |
Settlement analysis, allowable capacity |
| Ch 5 |
Spread Footings & Mats |
Raft foundations, combined footings |
| Ch 6 |
Deep Foundations: Types & Load Transfer |
Primary — pile classification, load transfer |
| Ch 7 |
Deep Foundations: Axial Capacity |
Primary — capacity, end bearing, skin friction, load tests |
| Ch 8 |
Deep Foundations: Lateral Loads, Groups & Settlement |
Group effects, downdrag, settlement |
| Ch 9 |
Drilled Shafts & Caissons |
Primary — construction, capacity, load tests |
| Ch 10 |
Lateral Earth Pressure |
Active/passive, braced cuts |
| Ch 11 |
Retaining Walls & MSE Walls |
Cantilever, counterfort, gravity, MSE |
| Ch 12 |
Sheet Pile Walls & Braced Excavations |
Cantilever, anchored, cofferdams; strut design |
| Ch 13 |
Slope Stability |
Excavation slopes, method of slices |
| Ch 14 |
Ground Improvement & Foundation Instrumentation |
Preloading, stone columns, grouting |
From Soil Mechanics & Geotechnical Engineering: A Public-Domain Reference (USACE / FHWA)
| Chapter |
Application |
| Ch 3 |
Classification — soil classification for foundations |
| Ch 4 |
Compaction — foundation bed preparation |
| Ch 5 |
Permeability — seepage under foundations |
| Ch 7 |
Effective Stress & Pore Pressure — K0, stress state |
| Ch 8 |
Stress Distribution in Soil — Boussinesq, influence charts |
| Ch 9 |
Consolidation — compressibility, settlement |
| Ch 10 |
Shear Strength — effective/total stress, pile capacity |
| Ch 12 |
In-Situ Testing & Parameter Selection — boring, sampling, SPT, CPT |
Typical Instrument Array for Foundation & Deep Excavation
| Instrument |
Purpose |
Dunnicliff Chapter |
Representative Instrument |
| Load cells |
Pile load tests, anchor load monitoring |
Ch 13, 24, 25 |
VW load cells, hydraulic load cells |
| Settlement plates |
Track consolidation under foundations |
Ch 12, 19 |
Settlement plates, wireless |
| Rod extensometers |
Deep foundation settlement, heave |
Ch 12, 24, 25 |
Rod extensometers, MPBX |
| Inclinometers (perimeter) |
Lateral movement of excavation walls |
Ch 12, 19 |
MEMS inclinometers, IPI arrays |
| Piezometers |
Dewatering pressures inside/outside |
Ch 9, 19 |
VW piezometers, wireless |
| Tiltmeters |
Adjacent building tilt |
Ch 12, 19 |
MEMS tiltmeters, wireless |
| Strut load cells |
Strut/anchor loads in braced cuts |
Ch 13, 19 |
VW load cells, hydraulic load cells |
| Telltales / crackmeters |
Foundation settlement, crack monitoring |
Ch 12, 13, 24, 25 |
Telltales, crackmeters |
| Strain gages |
Pile/ shaft strain, concrete stress |
Ch 13, 24, 25 |
VW strain gages, foil strain gages |
| AMTS / total stations |
Surface deformation, building monitoring |
Ch 12, 18 |
AMTS, wireless |
| GNSS / GNSS receivers |
3D displacement of structures |
Ch 12, 18 |
Locator One GNSS |
| wireless mesh |
Wireless data from all sensors |
Ch 8, 18 |
wireless mesh |
Installation Guidelines (from Dunnicliff Ch 9, 12, 13, 17, 19, 24, 25)
Pile Load Test Instrumentation
- Load cell: At pile head, calibrated
- Telltales: Multiple at different depths
- Strain gages: Along pile length (sister bar method)
- Reference benchmarks: Stable, outside influence zone
Drilled Shaft Instrumentation
- Base load cell: At shaft tip
- Side shear: Strain gages on cage
- Crosshole sonic logging: Integrity testing
- Tell-tales: For load transfer distribution
Braced Excavation Monitoring
- Strut loads: Load cells at each strut level
- Wall deflection: Inclinometers behind wall
- Groundwater: Piezometers inside/outside
- Surface settlement: Settlement plates, AMTS
- Adjacent buildings: Tiltmeters, settlement plates, AMTS
Dewatering Monitoring
- Piezometer arrays: Inside and outside excavation
- Flow measurement: Sump pumping rates
- Drawdown monitoring: Observation wells
Data Interpretation Guidelines (from Dunnicliff Ch 18, 19, 24, 25)
| Parameter |
Normal Range |
Alert Level |
Critical Level |
Reference |
| Pile head settlement (load test) |
< 5% pile dia |
> 10% pile dia |
> 20% pile dia |
Ch 24 |
| Strut load variation |
± 10% design |
> 20% design |
> 30% design |
Ch 19 |
| Excavation wall deflection |
< H/500 |
> H/300 |
> H/200 |
Ch 19 |
| Groundwater drawdown |
Design value |
2× design |
Loss of support |
Ch 19 |
| Adjacent building tilt |
< 1:1000 |
1:500 |
1:250 |
Ch 19 |
| Building settlement |
< 25 mm |
> 50 mm |
> 75 mm |
Ch 19 |
Automated Monitoring for Excavations (Dunnicliff Ch 18, Ch 19)
| System |
Function |
Implementation |
| Real-time strut loads |
Continuous strut load monitoring |
wireless load cells |
| Wall deflection |
Inclinometer + AMTS |
MEMS IPI + AMTS |
| Groundwater monitoring |
Inside/outside piezometers |
wireless piezometers |
| Surface settlement |
AMTS + GNSS |
AMTS + Locator One |
| Automated alarms |
Threshold exceedance |
cloud platform |
| Adjacent building monitoring |
Tilt + settlement |
Tiltmeters + settlement plates + AMTS |
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 Field Practice Video (RST Instruments): Data Logger Hardware Connections for Foundation Load Tests and Deep Excavation Strain Monitoring.
Complementary Practical Field Resources from RST Instruments & Measurand (Terra Insights)
- RST Instruments (@RSTgeotechnical): Connecting Instruments to Data Loggers
Field datalogger wiring and channel configuration for vibrating wire piezometers, load cells, and earth pressure cells in deep foundation elements.
- Measurand (@MeasurandVideos): How to install SAAV Extend
Deploying modular connectable ShapeArray for automated deep settlement and lateral deflection measurement in pile foundations and diaphragm walls.