The 5 most common methods of reinforcing weak soil today: Weak soil is inherently more suitable for growing trees and raising livestock. To be able to build large projects, it is required to strengthen the weak ground before placing the first brick. Join Uretek Vietnam to learn about the most effective methods of reinforcing the ground today!
What is soft ground? Is it possible to build a house on soft ground?
Have you ever heard that, for land areas near rivers, engineers often pour sand when making the foundation, wait for the sand to sink, then continue to pour, wait for it to sink, pour,… until the ground no longer sinks? Once done, start pressing piles. The workers had to do this because the ground near the river was quite weak.
Weak ground is ground that is susceptible to subsidence, has poor load-bearing capacity, and is easily deformed and destroyed under construction loads (high-rise buildings, large projects). Weak soil is usually soil near rivers, muddy soil, sandy soil, in contrast to soil in mountains and arid places.
In addition, in construction, a ground is assessed as weak based on physical criteria such as density; void coefficient; humidity; saturation or evaluation is also based on mechanical criteria such as: small load capacity; deformation module; compression coefficient; internal friction angle; adhesive force.
Weak soil is often more suitable for growing trees and raising livestock than building high-rise buildings or large projects. However, because of the need for construction and housing for the growing population in urban areas, weak soil is also used to build projects.
To create a solid foundation, it is necessary to reinforce weak ground before construction.
The most popular and effective methods of reinforcing soft ground today
Reinforcing weak ground is intended to increase the bearing capacity of the ground and improve physical indicators such as: reducing void ratio; Reduce compaction settlement; increase compaction;… Soil treatment for irrigation works can reduce soil permeability.
The treatment of weak soil includes the following two basic methods: replacing weak soil and strengthening weak soil.
Common methods of reinforcing soft ground
There are 3 common methods:
- Mechanical methods: Including compaction methods by compaction, vibrating compaction, sand wells, soil replacement methods, sand cushions,…
- Physical methods: Including methods of lowering the water table, using sand wells, wicks, electro-seepage, etc.
- Chemical methods: Including methods of making soil glue with cement, cement mortar, silicate method, electrochemical method,…
Below, Uretek Vietnam will explain more clearly some of the popular methods.
Method of reinforcing weak ground with sand piles (also known as sand wells)
This method is different from the common methods of treating the ground with hard piles (concrete, reinforced concrete, bamboo wood piles,…). Sand piles are responsible for bearing, receiving and transmitting loads to the ground.
Advantages of using sand piles:
- Helps water from pores drain faster.
- The process of soil consolidation and stable settlement occurs faster.
- Simple construction, cheap materials.
Method of reinforcing weak ground with soil-cement piles
Soil-cement piles are often used to treat weak soils such as peat, silt, clay and clay loam.
Soil-cement piles are a combination of soil and cement in a certain ratio (additives can be mixed) to form a type of mechanical pile with the composition of natural soil but stronger, increasing durability. stability and settlement of the land.
Advantages of reinforcing soft ground with soil-cement piles:
- Once the ground is treated with soil and cement piles, the settlement index is reduced to a very small level, there is no need to spend additional materials to compensate for settlement, and there is no need to wait for the ground to consolidate, speeding up construction progress.
- Can be constructed in flooded soil conditions.
- Noise and vibration are small and do not affect the surrounding environment much.
Reinforcement method with sand cushion
The method of reinforcing weak soil with sand cushions is to replace the weak clay layer above with a more compacted, stronger layer of sand and gravel. During construction, workers will excavate part of the soft soil layer and replace it with a compacted layer of medium- and coarse-grained sand.
The method of reinforcing weak soil with sand cushion applies to soft soil layers in a water-saturated state (soft clay, mud, peat,…) and a thickness of less than 3m.
Uses of reinforcing soft ground with sand cushion:
- The new sand cushion layer increases the load-bearing capacity, increases the ability to absorb construction loads and helps transmit that load to the soft soil layers below better.
- Helps reduce subsidence of the building.
- Reducing foundation depth when pressing piles, saving construction materials.
- Compacted sand increases friction and slip resistance, thereby increasing the stability of the project horizontally and vertically, reducing soil consolidation time, and speeding up the stabilization time for the project.
Measures to reinforce weak ground by compacting the topsoil
One of the measures to reinforce weak ground is to compact the topsoil. For soft soil with low moisture (G < 0.7), this method can be used.
This method creates a tight, hard soil buffer layer, takes advantage of the natural ground to lay the foundation, and reduces the volume of excavation. To compact the topsoil, there are many different methods, one of the most commonly used is the shock compaction method.
Advantages of the method of reinforcing soft ground and compacting the topsoil:
- Improves the load-bearing capacity of the ground.
- Improve consolidation time, quickly increase stable settlement over time.
Method of reinforcing weak ground – Wicking
This method of reinforcing weak soil uses vertical drainage techniques using permeable wicks combined with preloading.
In many cases, absorbent wicks are also used to conduct water horizontally on the ground.
In ground reinforcement construction, permeable wicks are used to speed up the drainage process of soft soil, reduce water-filled voids, increase soil density, speed up soil consolidation, and increase load-bearing capacity. , helping the ground reach the specified settlement level.
Thus, weak ground needs to be reinforced before starting construction. There are many different ways to handle weak ground, depending on each specific case, you should apply the most suitable method!
