In-situ-testing

EARTH RESISTIVITY TEST

EARTH RESISTIVITY TEST

– For construction projects, especially large ones such as high buildings, power plants, transmission grids, transformer stations, the resistivity value of soil is an important parameter to design earthing system, ensure safe and efficient operation …

 

– With teams of well-trained geotechnical engineers, many years of experience in site survey including measuring the resistivity of the ground, along with modern equipment such as the French’s brand CA6470N resistivity meter, the Japanese Kyoritsu 4106, we are committed to provide soil resistivity measurement service for design work with high reliability and reasonable cost.

Steps to perform the SPT test:

– Step 1: Drill to the test depth, cleaning & dredged muck from bottom of the borehole, and install equipment according to standards.

– Step 2: Mark 3 equal intervals (15cm) on the drliing rod.

– Step 3: Release the donut hammer in free fall and count the total number of hammers through the marked segments.

– Step 4: Take the hammer number of the last 2 segments as SPT index

– Step 5: Uninstaling SPT inquipment and remove SPT sample, repeat the steps when performing the experiment at the next times.

Thí nghiệm xuyên tiêu chuẩn - Standard penetration test (SPT)

Figure 1:Standard Penetration Test

 

Figure 1:Standard Penetration TestTools for Standard Penetration Test:
1. Standard Split Spoon Sampler
2. Drop Hammer weighing 63.5kg
3. Guiding rod
4. Drilling Rig.
5. Driving head (anvil).

 

The main purpose of the test is to provide an indication of the relative density of granular deposits, such as sands and gravels from which it is virtually impossible to obtain undisturbed samples. The great merit of the test, and the main reason for its widespread use is that it is simple and inexpensive.
The usefulness of SPT results depends on the soil type, with fine-grained sands giving the most useful results, with coarser sands and silty sands giving reasonably useful results, and clay and gravelly soils yielding results which may be very poorly representative of the true soil conditions.

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