Poor soil foundation practices
- Chemical methods: Including methods of cement glue for soil, silicate, electrochemical.
- Physical methods: including the lowering of the groundwater table, the use of sand wells, penetrations, permeability.
- Mechanical methods: sand compression method, piles (soil pile, sand pile, lime pile), soil replacement, sand cushion, geotextile.
Treatment of weak soil with absorbent wicks
A longitudinal drainage plan using a wick seal coincides with pre-loading. When the soil thickness is very weak or when the permeability of the soil is very small, the vertical permeability can be arranged to increase the consolidation rate. This alternative is used to handle embankments on weak ground.
The PVD method has vertical infiltration effect to speed up the drainage process in the space of weak soil, moisture, reduce the porosity, increase the density. The result is a rapid increase in weak soil consolidation, increased load carrying capacity and adequate level of ground clearance.
How to preload compression
This method can be used to treat weak soils such as clay, peat, and clay.
Using this method has the following good points
- Increased stability over time, speeding up consolidation.
- Rapid increase in bearing capacity of the ground.
Measures taken:
- Using sand wells or penetrations to drain water out of the gaps, increase the accumulation of soil, increase the rate of subsidence over time. Depending on the requirements of specific works, geo-technical conditions and hydro-geological conditions of the site, appropriate or individual remedies may be used, or in combination with both.
- Gravel (gravel, sand, stone, brick ...) Equally or larger work load is expected to be designed on weak ground, to select pre-loaded foundation and subsidence before construction.
Compaction method of topsoil
In the case of weak soils with a small moisture content (g <0.7), the soil compaction method can be used to reduce the soil's shear strength and to reduce compression. The top soil after compaction will act as a buffer layer of soil, not only the advantages of the sand-cushioning scheme, but also the advantage of using natural soil to lay the foundations, reducing the amount of excavated mass. One can use many methods to consolidate the topsoil. The most common method is to shock:
In this way the weight of the fruit is not less than 1m and from 1 to 4 tons (sometimes 5-7 tons). In order to have good results in choosing the dress, static pressure caused by clay and 0.15 kg / cm2 and lagoon size of not less than 0.2 kg / cm2 should be ensured.
Floor treatment with sand mattress
Sand is used effectively for weak soils in saturated water (clay, clay, sand, peat, mud, etc.) and a thickness of less than 3m of weak soil.
Method of implementation: excavation of some or all of the weak soil layer (in case of weak soil layer) and instead of medium grain sand, compacted seeds. Replacing weak soil with bottom sand has the following major impacts:
- In terms of simple construction, no need to use modern equipment quite spacious. Application area is best if soil layer is less than 3m. This method should not be used when the soil has a high water level and water pressure because it is costly to lower the water table and buffer will be less stable.
- Increases the stability of the structure, even in horizontal loads, by compressed sand to increase friction and slip resistance. Accelerate the consolidation of the ground to increase the load bearing capacity of the foundation and increase the settling time for the building.
- Reduce work pressure down to the value that the weak ground can receive.
- Reducing burial depth should reduce the amount of nail material.
- The subsidence and settlement of the structure is reduced due to the external load caused by stress repetition caused by the sand layer.
Sandstrap acts as a load bearing layer, sand substitutes poor soil under the bottom of the foundation, absorbs the load of the project and transmits that the soil is weak.
Treatment of cement pile, soil - cement
Limestone quarry is used for treating and compressing sludge, peat, plastic clay. The problem with using limestone piles has the following effects:
- Handled by improved lime: adhesion increased 1.5 - 3 times, soil moisture decreased 5 - 8%;
- The diameter of the pile will increase by 20% to make the soil around the pile compact when the limestone pile is compacted. When lime touches the hole, the water evaporates, moisture decreases and accelerates the compression as it releases large amounts of heat.
The production of cement piles is similar to the soil pile, where silo containing cement and soil spray are pre-defined. Note that the cement sieve should be poured into the silo to ensure that cement particle cements are <0.2mm in size and no lumps, therefore the nozzle is not blocked. The cement content is likely to be between 7 and 15% and the results indicate that cement strength is better than slurry and lime sand is more effective than clay.
The method of treating the soil by sand piles
Sanding piles are different from other types of hard piles (bamboo piles, piles, reinforced concrete, concrete, etc.). As part of the foundation, responsible for receiving and transfering the soil. soil, sand pile network to strengthen weak ground, also known as sand piles. The problem with the use of sand piles to strengthen the background has the following advantages:
- Simple, cheap sand piles should be more cost effective than other types. Sand piles are used to reinforce weak soils with a thickness of> 3m.
- Sand pits act as sand wells, giving quick drainage through holes, speeding up the process of consolidation and stabilization. The ground is firmly pressed by steel pipes, then the soil is compacted. The water in the soil is forced into the sand hole, so the strength of the ground increases
Weak land is risky and risky for unsafe construction. Studies on weak soils and identification of appropriate treatments are important. In practice, it is necessary to base on the geological condition of the specific works to be handled properly.
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