The soil undisturbed sampler is used to collect undisturbed soil samples from underground and is widely used in fields such as soil engineering survey, environmental monitoring, and agricultural research. When collecting undisturbed soil samples, the sampler needs to maintain the natural structure and physical properties of the soil as much as possible, so the sampling method must be strict and accurate. The following are common sampling methods for soil undisturbed samplers:
1. Preparation before sampling
Determine sampling location: Select appropriate sampling points according to engineering requirements or research needs. The sampling points should meet the requirements of soil sample representativeness and randomness.
Cleaning tools: Ensure that the sampler, steel pipe, shovel, and other tools are clean to avoid cross contamination.
Exploration hole setting: According to the sampling depth requirements, drilling of exploration holes should be carried out first. Common drilling equipment includes manual drills, mechanical drills, etc. The depth of exploration holes is determined according to the specific needs of the project.
2. Selection of soil undisturbed sampler
There are various types of soil undisturbed samplers, including:
Cylindrical sampler: suitable for collecting general soil.
Cone sampler: suitable for harder soils such as clay and cohesive soil.
Spiral sampler: used for collecting deeper or loose soil.
Dual tube sampler: suitable for sampling deep and complex soil layers.
Choosing a suitable sampler can help maintain the soil's original state to a large extent.
3. Sampling operation
Entering the borehole: Use a suitable soil undisturbed sampler to vertically insert it into the borehole, ensuring that the sampler does not tilt.
Sampling depth: According to engineering or research requirements, each sampling depth is usually 20-30cm, and if necessary, stratified sampling at different depths can be carried out according to changes in soil layers. For deep sampling, it is necessary to advance layer by layer.
The footage control of the sampler: During the sampling process, it is important to ensure that the sampler enters the soil layer vertically and stably, avoiding lateral compression or damage to the soil layer. The commonly used method is to slowly and evenly push the sampler.
Prevent soil sample disturbance: During the sampling process, ensure that the soil sample inside the sampler remains in its original state. Prevent the soil sample in the sampler from being subjected to vibration or compression, and prevent the moisture and structure of the soil sample from being damaged.
4. Processing after sampling
Take out soil sample: After the sampler enters the soil layer, use appropriate tools (such as a soil sampler or manual operation) to extract the sampler. When extracting, attention should be paid to avoiding disturbing the natural structure of the soil sample.
Sample stratification: If the sampling depth is large, it is usually necessary to sample according to the soil layer stratification and store them separately. Each level of soil sample needs to be clearly marked, recording the sampling depth and soil layer characteristics.
Soil sample sealing and packaging: After soil sample collection, it should be sealed in a timely manner to avoid exposure to air that may cause moisture loss or contamination. Usually, plastic bags or sealed containers are used for packaging. In special circumstances (such as detecting soil moisture content), it is advisable to quickly seal the sample after sampling.
5. Soil sample recording and identification
When sampling, basic information of each sample should be recorded, including sampling date, time, location, depth, soil layer type (such as clay, sand, loam, etc.), surrounding environmental conditions, etc.
The information such as sample number, sampling location, and depth needs to be clearly identified for subsequent analysis and testing.
6. Precautions
Avoid external pollution: When sampling, avoid contact between the sampler and other objects to avoid contaminating the soil sample.
Maintain soil moisture: Some soils such as clay and wet soil may easily disintegrate, so it is important to maintain soil moisture as much as possible.
Sampler design: Different soil types require the selection of different types of samplers, for example, hard soil layers may require the use of conical or spiral samplers.
7. Handling in special circumstances
Surface soil sample: When collecting surface soil samples, it may be greatly affected by human activities or plant roots, and these interference areas can be avoided.
Soft soil sampling: For softer soil layers, it may be necessary to use undisturbed samplers with reinforced structures to prevent soil samples from collapsing or being compressed.
The impact of groundwater level: When sampling, the influence of groundwater should be considered, especially in humid or high water level areas, which may require special methods (such as multiple sampling, drying treatment, etc.).
summary
The key to soil undisturbed sampling is to preserve the natural structure and moisture of the soil as much as possible, and to ensure the representativeness and accuracy of the collected samples through reasonable sampling methods and equipment selection. During the sampling process, it is essential to avoid external interference and contamination to ensure the reliability of subsequent analysis results.