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Soil Nail Walls��Module 5: Testing and Monitoring

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Introduction

Training support files are available as attachments from the resources link.

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Course Map

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Course Map

Module 1

Module 2

Module 3

Module 4

Module 5

Introduction to Soil Nail Walls

Fundamentals of Soil Nail Walls

Pre-Construction and Construction

Construction Inspection Activities

Testing and Monitoring

Production: Please add relevant icons for each module. Do not use the example shown for Module 5.

Testing and Monitoring

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Module Overview

This module will take approximately 45 minutes to complete.

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Module Overview

Testing

Types of Tests

Monitoring

Testing and Monitoring

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Module Learning Outcomes

Upon completion of this module, you should be able to:

Explain the importance of testing during and after soil nail wall construction
Summarize the types of tests that should be performed as part of soil nail wall construction
Describe the importance of monitoring soil nail walls after construction

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Module Learning Outcomes

Testing and Monitoring

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Testing

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Testing

In the last module…

Write your answer in the provided box and then select submit.

What do you think?

Type your thoughts here:

1a

1b

Submit

Testing and Monitoring

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Testing

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Testing

Verify that soil nails can carry the load without much movement

1b

First, to verify that soil nails can carry the design loads without too much movement

Were you able to think of something? There are…

1b

1c

You can see a typical load test set up …

1a

1c

Testing and Monitoring

Script (Jake): Were you able to think of something? There are several reasons why testing is important. Here are two reasons that stand out. First, to verify that soil nails can carry the design loads without too much movement. We don’t want nails shifting under pressure. Testing helps confirm that each the nails are strong enough to hold back the soil – the loads they were designed to resist – and that they will stay stable while doing it. You can see a typical load test setup in the image here. The equipment applies force to the nail and measures how much it moves.

Production: Recreate an animated sequence. Part 1 of 2 (all parts are on the same slide).

Navigation: Animated sequence advanced to the next screen

Image: Man in hard hat and vest holding a sign

Source: Articulate

Image: Soil nail load testing setup , p.244

Source: FHWA GEC 007 Soil Nail Walls Reference Manual 7^th edition

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Testing

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Testing

Is the contractor’s method working?

Watch for soil changes

Field conditions may lead to more testing

Another reason it’s important…

Testing is used to verify the contractor’s…

...additional testing may be needed…

If the subsurface conditions…

2c

2d

2b

2a

2b

2c

2d

Testing and Monitoring

Script (Jake): Another reason it's important to test soil nails is to check how well the contractor’s methods are working. Testing is used to verify the contractor’s drilling, installation, and grouting operations before and during construction of the soil nail wall. If the ground conditions turn out to be different than expected, or if the contractor needs to adjust their drilling or grouting methods during construction, additional testing might be needed to make sure those changes don’t affect the wall’s performance. If the subsurface conditions such as soil type or moisture vary along the wall, those areas may need to be tested individually, even if they weren’t originally marked for testing.

Production: Recreate an animated sequence. Part 2 of 2 (all parts are on the same slide).

Navigation: Animated sequence advanced to the next screen

Image: Excavation of soil lift during construction of a soil nail wall , p.48

Source: FHWA GEC 007 Soil Nail Walls Reference Manual 7^th edition

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Testing

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Testing

Now, let’s talk about what happens…

Select each question to …

What happens if the test results are not acceptable?

Where are the testing procedures and acceptance criteria described?

What are the inspector’s responsibilities during testing?

Testing and Monitoring

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Testing

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Testing

What happens if the test results are not acceptable?

Where are the testing procedures and acceptance criteria described?

What are the inspector’s responsibilities during testing?

What happens if the test results aren’t acceptable?

Contractor must revise their methods
Inspector documents and reports the issue
Engineer decides how to proceed

Testing and Monitoring

Script (Jake): What happens if the test results are not acceptable? If the results show that the nails aren’t performing as expected, or indicate poor construction practices, the contractor is expected to revise their methods. That might include changes to how nails are drilled, installed, or grouted. The inspector doesn’t tell the contractor what to do, but they do document the results and report concerns to the engineer who will then decide how to move forward.

Production: Pop up for question “What happens if the test results aren’t acceptable?”

Navigation: User selects X to return to three-question menu

Image: Soil nail wall load testing, Salt Lake City, UT

Source: FHWA-HRT-08-014 https://www.fhwa.dot.gov/publications/focus/08jun/02.cfm

Image: Question Mark

Source: Adobe Stock, File# 732952650, Educational License (team member)

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Testing

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Testing

What happens if the test results are not acceptable?

Where are the testing procedures and acceptance criteria described?

What are the inspector’s responsibilities during testing?

Where are the testing procedures and criteria described?

Procedures and criteria are in the project specifications
Specs explain how testing done and what counts as “passing”
Inspectors use the specs to evaluate test results

SMEs, do you have high quality examples of project specifications?

Testing and Monitoring

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Testing

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Testing

What happens if the test results are not acceptable?

Where are the testing procedures and acceptance criteria described?

What are the inspector’s responsibilities during testing?

Observe each load test and log the results
Confirm follows contractor submittals and project schedule
Suggest which nails to proof test, based on field conditions

Testing and Monitoring

Script (Jake): The inspector has several important responsibilities during testing. First, they must observe each load test and log the results. They’re also responsible for making sure the testing follows the approved submittals provided by the contractor, as the schedule in the project specifications. And based on what they see during construction, inspectors may provide input on which nails should be selected for proof testing.

Production: Pop up for question “What are the inspector’s responsibilities during testing?”

Navigation: User selects X to return to three-question menu. Auto advance when all questions are visited

Image: Man in construction vest and hard hat with left hand out

Source: Articulate

Image: Typical testing setup

Source: Soil Nailing Filed Inspectors Manual, page 49

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Types of Testing - setup

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Setup

…shown in the plan details

The equipment often includes…

Hydraulic jack

Load cell

Dial gauges

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1b

1e

1c

1d

SMEs, do you have high quality examples of plan details and corresponding testing images?

Testing and Monitoring

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Testing

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Testing

Now that you’ve seen the setup and equipment…

Select each type to learn…

Proof Tests

Verification Load Tests

Creep Tests

Testing and Monitoring

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Verification Load Tests

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Verification Load Tests

Proof Tests

Verification Load Tests

Creep Tests

Verification Load Tests

Sacrificial nails are for testing only
Hydraulic jack applies force to pull the nail away from the wall
Nail is tested at higher-than-normal pressure
Unbonded length isolate nail from the wall

SMEs, do you have photos or a short video?

Testing and Monitoring

Script (Jake): Verification load tests are an important part of making sure the soil nails can handle the load specified in the design. A set number of dedicated sacrificial nails are used for this verification and won’t be part of the finished wall. In this test, a hydraulic jack applies force along the length of the nail, pulling it away from the wall. This simulates the pressure the nail would experience from the surrounding soil once the wall is in place. The test uses a higher pressure than the nail would typically see in service. These test nails usually include an unbonded length, which is a portion near the shotcrete wall that’s left ungrouted. This isolates the nail from the wall and ensures the test measures how the nail interacts with the soil, not the wall.

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Production: Pop up for “Verification Load Tests”

Navigation: User selects X to return to menu. All three types must be explored before moving on.

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Verification Load Tests

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Proof Tests

Verification Load Tests

Creep Tests

Proof Tests

Similar to verification tests, but nails stay in the wall
May occur before or early in construction
Spot checks continue during construction
Uses lower pressure than verification testing
Includes an unbonded length

SMEs, do you have photos or a short video?

Testing and Monitoring

Script (Jake): Proof tests are similar to verification tests, but there are some important differences. Instead of using a sacrificial nail, proof tests are done on the same nails that will remain in the wall. These tests help confirm that the nails are performing as expected under real site conditions. Some project specifications may require proof tests before construction gets fully underway, or within the first few days. They can also happen throughout construction to spot-check performance.

Like verification tests, a hydraulic jack applies force to pull the nail away from the wall to simulate soil pressure. But unlike verification tests, the pressure here is lower and not meant to push the nail to its limits.

Proof tests also use an unbonded length. You may recall that is the section of the nail near the shotcrete wall that’s left ungrouted. It helps isolate the test so it measures how the nail interacts with the soil—not the wall.

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Production: Pop up for “Proof Tests”

Navigation: User selects X to return to menu. All three types must be explored before moving on.

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Creep Tests

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Creep Tests

Proof Tests

Verification Load Tests

Creep Tests

Part of verification or proof testing
Test applies steady pressure over time
Measures nail movement at intervals
Load must hold for 10-60 minutes
Too much “creep” signal potential problems

SMEs, do you have results of a creep test that failed and one that passed?

Testing and Monitoring

Script (Jake): Creep tests are performed as part of verification or proof testing. They’re used to see how a soil nail behaves when it’s under a constant load for a longer stretch of time. During this test, a hydraulic jack applies steady pressure on the nail. The nail’s movement is measured at different timed intervals, typically over a sustained hold period of 10 to 60 minutes. The goal of the test is to confirm the nail can safely carry the intended load throughout the life of the wall. It helps verify that the nail won’t keep shifting, or “creeping,” under pressure. A little movement is expected, but too much could be a sign of trouble.

If the nail’s movement stays within acceptable limits, it passes the creep test. If not, that could indicate poor soil bonding or potential long-term performance issues.

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Production: Pop up for “Proof Tests”

Navigation: User selects X to return to menu, or next when all three types have been explored.

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Monitoring

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Monitoring

Once a soil nail wall is built…

…regularly check the underdrain outlets…

Without a way for water to escape…or even wall failure, as shown here.

1a

1b

1c

1a

Testing and Monitoring

Script (Jake): Once a soil nail wall is built, it still needs attention to make sure it performs well over time. Even small issues, like clogged drains, can become serious if they’re not caught early. Drainage is the most important thing to monitor because if water builds up behind the wall, it adds pressure the wall wasn’t designed to handle. That’s why it’s important to regularly check the underdrain outlets to make sure they’re clear and water can flow out safely. This photo shows what can happen when drainage isn’t maintained. Without a way for water to escape, excessive pressure builds up and can cause damage, or even wall failure, as shown here.

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Production: Recreate an animated sequence.

Navigation: User selects next to advance.

Image: Man in construction vest and hard hat

Source: Articulate

Image: Failure of wall caused by incomplete grouting and drainage, p.17

Source: Texas Tech University “Non-Destructive Evaluation of Installed Soil Nail”

https://library.ctr.utexas.edu/hostedpdfs/techmrt_0-4484-1.pdf

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Monitoring

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Monitoring

Now that you’ve seen…

Select each key area to learn…

Ground Movement

Signs of Distress

Routine Maintenance

Monitoring after construction

Testing and Monitoring

Script (Jake):. Now that you’ve seen how important drainage can be, let’s talk about what else should be monitored after a soil nail wall is built. Even if the wall looks fine from the outside, small signs of trouble can show up over time. Select each key area to learn what should be monitored after construction.

Production: Pop up interaction for each area.

Navigation: User selects X to return to menu. All three areas must be explored begore moving on

Image: Man in construction vest and hard hat talking and pointing left

Source: Articulate

Image: Three-up pop-up menu

Source: Adapted from Infographia.com (team member subscription)

Image: Ground movement icon

Source: Flaticon: https://www.flaticon.com/free-icon/displacement_16891797?term=ground+movement&page=1&position=10&origin=search&related_id=16891797

Image: Warning icon

Source: Flaticon: https://www.flaticon.com/free-icon/warning_10629599?term=beware&page=1&position=2&origin=search&related_id=10629599

Image: Maintenance

Source: Flaticon: https://www.flaticon.com/free-icon/mechanic_11133669?term=maintenance&page=1&position=9&origin=search&related_id=11133669

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Monitoring

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Ground Movement

Now that you’ve seen…

Select each key area to learn…

Ground Movement

Signs of Distress

Routine Maintenance

Monitoring after construction

Monitor Ground Movement

Ground movement is measured with an inclinometer

Place in pipe installed deep into wall
Tracks horizontal movement of soil
Identifies early signs of instability

Testing and Monitoring

Script (Jake):. Ground movement is something that should be monitored after a soil nail wall is built. A common tool for this is an inclinometer. An inclinometer measures how much the ground shifts over time. It’s placed in a pipe that’s installed deep into the ground behind the wall. By tracking horizontal movement in the soil, it can help identify early signs of instability before they’re visible at the surface. Long-term performance of a soil nail wall depends on routine inspection and monitoring. Inclinometers are one way to keep an eye on how the wall is performing over time.

Production: Pop up for ground movement

Navigation: Users select X to return to menu. All three areas must be explored before moving on

Image: Performing measurements using a traversing inclinometer, p. 27

Source: Transportation Research Circular, October 2008 “Use of Inclinometers for Geotechnical Instrumental on Transportation Projects” https://onlinepubs.trb.org/onlinepubs/circulars/ec129.pdf

Image: Three-up pop-up menu

Source: Adapted from Infographia.com (team member subscription)

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Monitoring

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Signs of Distress

Now that you’ve seen…

Select each key area to learn…

Ground Movement

Signs of Distress

Routine Maintenance

Monitoring after construction

Monitor Signs of Distress

Not all monitoring is done by inspectors
Site and maintenance staff need to know what to monitor

Cracks in shotcrete
Rust on nail heads
Wall tilting

Long-term performance of soil nail walls depend on routine inspection and monitoring

Nail head with rust

Testing and Monitoring

Script (Jake):. Not every person monitoring a soil nail wall will be an inspector. Maintenance staff or other workers on site might be the first to notice signs of trouble, so it's important they know what to look for. Cracks in the shotcrete, rust on nail heads, or parts of the wall that appear to be tilting can all be early signs of distress. These issues can be clues that the wall isn’t performing as expected. Long-term performance of soil nail walls depends on routine inspection and monitoring. Visual checks are a key part of catching problems early before they grow into serious concerns.

Production: Pop up for monitor signs of distress

Navigation: Users select X to return to menu. All three areas must be explored before moving on

Image: Nail with rusty head, p.196/262

Source: Texas Tech University “Non-Destructive Evaluation of Installed Soil Nail”

https://library.ctr.utexas.edu/hostedpdfs/techmrt_0-4484-1.pdf

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Monitoring

Menu:[indent]

Routine Maintenance

Now that you’ve seen…

Select each key area to learn…

Ground Movement

Signs of Distress

Routine Maintenance

Monitoring after construction

Routine Maintenance

Perform maintenance on a regular basis
Clear vegetation near the wall
Repair cracks in shotcrete facing
Check for wear or corrosion around nail heads
Simple checks extend the life of the wall and prevent more serious problems

SMEs, do you have images of any maintenance activities?

Cracks in shotcrete may lead to wall failure

Testing and Monitoring

Script (Jake):. Routine maintenance activities should be planned and performed on a regular basis to support the long-term performance of the wall. Common tasks include clearing vegetation near the wall, repairing cracks in the shotcrete facing, and checking for signs of wear or corrosion around nail heads. These simple checks help protect the wall’s structural components and reduce the risk of water buildup. When done routinely, they can extend the life of the wall and help prevent more serious problems down the line.

Production: Pop up for routine maintenance

Navigation: Users select X to return to menu. All three areas must be explored before moving on

Images: Moment of collapse of a soil nail wall in Coquitlam, Canada (screenshot)

Source: Geoengineer.org https://www.geoengineer.org/videos/xpljsfN6a1aKPPWt

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Limitations of Soil Nail Walls

Read each description and review the photo. Decide which type of test is being shown, then select the correct answer and click Submit

1). This test uses a hydraulic jack to pull on a nail that will remain in the wall.

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Knowledge Check – Which Test is This?

Submit

1). This test uses a hydraulic jack to pull on a sacrificial nail that will not be part of the wall.

1). This test measures nail movements at different time intervals. The goal is to ensure the wall doesn’t shift too much.

Proof Test

Verification Load Test

Creep Test

Loads applied up to 200%

Loads applied up to 150%

Proof Test

Verification Load Test

Creep Test

SMEs, do you have images of creep testing?

Proof Test

Verification Load Test

Creep Test

Testing and Monitoring

Script (Jake): Way to go! You’re nearly at the end of the course. We’ve covered a lot of material in this fifth module, so let’s do a knowledge check! Read each description and review the photo. Decide which type of test is being show, then select the correct answer from the drop-down menu. When you’re satisfied with your answer, select submit.

Production: Knowledge check where participant selects the correct test and then Submit. Up to two incorrect attempts before debrief. Correct answers are verification load test / creep test / proof test.

Navigation: User selects three answers and then Submit.

Image:: Test Setup for Soil Nail Load Testing, p.13

Source: Texas Tech University “Non-Destructive Evaluation of Installed Soil Nail”

https://library.ctr.utexas.edu/hostedpdfs/techmrt_0-4484-1.pdf

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Read each description and review the photo. Decide which type of test is being shown, then select the correct answer and click Submit

1). This test uses a hydraulic jack to pull on a nail that will remain in the wall.

Menu: [indent]

Debrief– Which Test is This?

Debrief – Which Test is This?

Submit

1). This test uses a hydraulic jack to pull on a sacrificial nail that will not be part of the wall.

1). This test measures nail movements at different time intervals. The goal is to ensure the wall doesn’t shift too much.

Verification Load Test

Loads applied up to 200%

Loads applied up to 150%

Proof Test

SMEs, do you have images of creep testing?

Creep Test

Testing and Monitoring

Script (Jake): Nice work! Let’s review the correct answers. The answer for the first question is Verification load test. This type of test uses a sacrificial nail that won’t be part of the finished wall. A hydraulic jack pulls on the nail with high pressure to make sure it can handle the load specified in the design. The answer for the second question is a Creep test. This test measures how much a soil nail moves when steady pressure is applied over time. It helps confirm the nail can carry the load throughout the life of the wall without continued movement. The answer to the third question is Proof test. This test is done on production nails early in construction. It uses lower pressure than a verification test to check that the nails are performing as expected under real site conditions.

If you had trouble identifying any of the soil nail wall tests, you can go back and review any part of this module. Otherwise, select “Next” for a quick review of what you learned in this module.

Production: Example debrief layout. Make it as clean and readable as possible

Navigation: Users select “Next” to advance to the next slide

Image:: Test Setup for Soil Nail Load Testing, p.13

Source: Texas Tech University “Non-Destructive Evaluation of Installed Soil Nail”

https://library.ctr.utexas.edu/hostedpdfs/techmrt_0-4484-1.pdf

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Learning Outcomes

You should now be able to:

Explain the importance of testing during and after soil nail wall construction
Summarize the types of tests that should be performed as part of soil nail wall construction
Describe the importance of monitoring soil nail walls after construction

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Learning Outcomes

Testing and Monitoring

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Summary

This concludes Module 5: Testing and Monitoring.

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Module Complete

You have reached the end of this module.

Select the next module to continue.

Testing and Monitoring