CPTU - Post CPT (after ground improvement) Cone Penetration Test - Ayaan And Ayhaam

Summary

This video demonstrates the process of conducting a post-CPT (Cone Penetration Test) to assess ground improvement after compaction. The team sets up the safety rig, performs saturation with grease to prevent air voids, and uses a cone to measure soil resistance. They document the QC values, which initially increase and then decrease, indicating compaction quality. The test continues until a refusal depth of 7 meters is reached, with the QC value indicating acceptable ground conditions. The video also discusses the importance of maintaining pressure and adding rods as the test progresses.

Takeaways

• 🔧 The video discusses a post-CPT (Cone Penetration Test) procedure following ground improvement work using wire Pro compaction methods.
• 👷‍♂️ Safety rig setup is highlighted as an essential step before conducting the CPT.
• 💧 The video mentions dealing with poor water pressure, which may require saturation with the cone, a topic to be covered in a separate video.
• 📍 The process involves setting out points, ID, coordinates, and levels before starting the penetration test.
• 📉 The QC (Quality Control) value is used to assess the effectiveness of the ground improvement, with a minimum acceptable criteria of over 10.
• 🔩 The video explains the procedure of adding rod links every meter during the drilling process.
• 📊 The script describes the use of graphs to monitor the QC values and the refusal criteria during the CPT.
• 🚧 The ground improvement's minimum criteria are discussed, emphasizing the importance of achieving a QC value greater than 10.
• 📏 The video mentions the refusal depth, which is considered acceptable when the QC value is at least 50, with a target refusal depth of around 7 meters.
• 🔍 The final part of the video script describes reaching the refusal point, indicated by a sudden straight line in the QC graph, signifying an increase in the QC value.

Q & A

What is the purpose of the post CPT test mentioned in the script?

The post CPT (Cone Penetration Test) test is performed to check the results of ground improvement efforts, specifically after using wire Pro compaction methods.

What does the term 'saturation with the cone' refer to in the context of the video?

Saturation with the cone refers to the process of saturating the soil sample with water to ensure that the soil is fully saturated before conducting the CPT test, which is crucial for accurate results.

Why is it important to avoid air voids during the saturation process?

Air voids can lead to inaccurate measurements and results during the CPT test. Grease is used to avoid air voids, ensuring that the soil sample is fully saturated without any air pockets.

What are the two methods mentioned for saturation, and which one was used in the video?

The two methods for saturation are without rain and with grease. In the video, the method with grease was used for saturation.

What is the significance of the QC value in the context of the ground improvement process?

The QC value, or Quality Control value, is used to assess the effectiveness of the ground compaction. A QC value of more than 10 indicates acceptable compaction, while values less than 10 suggest that the compaction is not sufficient.

What does the term 'refusal' signify in the CPT test?

Refusal in the CPT test refers to the point at which the cone can no longer penetrate the soil. A minimum QC value of 50 is considered acceptable at refusal.

How is the depth of penetration measured during the CPT test?

The depth of penetration is measured by the length of the rods used in the test. After each meter of penetration, an additional rod is installed, and the test continues.

What is the significance of the pore pressure and tilt angle readings during the CPT test?

The pore pressure and tilt angle readings provide additional data about the soil conditions. Pore pressure indicates the pressure within the soil's pores, while the tilt angle measures the inclination of the cone, both of which are important for interpreting the test results.

Why is it necessary to recharge the ground during the CPT test?

Recharging the ground may be necessary to ensure that the cone can penetrate the soil effectively. It helps in verifying the soil's resistance and compaction status.

What is the minimum depth considered for refusal in the area being tested?

In the area being tested, the refusal is considered at a minimum depth of 7 meters, as indicated by the sudden straight line in the QC value readings.