Soil consolidation is the artificial change in its characteristics. For this purpose, various physical and chemical methods are used. Thanks to this type of transformation, it is possible to increase the strength of the soil, make it more stable, reduce compressibility and water resistance. Today there are many ways to consolidate soil, each of which has certain pros and cons.
Methods for consolidating soils
There are a large number of methods for strengthening soils. They differ significantly from each other and have certain pros and cons.
Chemical fixation
This type of soil strengthening is carried out using different methods - using cementation, resinization, silicatization. The most common technology is cementation. This term refers to the process of injecting liquid cement mortar or milk into the soil. Hollow piles are first driven into the ground.
Cementation is suitable for fractured rocks. This procedure is also suitable for sandy soil, which consists of large and medium fractions. Depending on the porosity of the sand or the size of the cracks, different ratios of cement and water may be used. Also, additional substances are often added to the composition - sand, clay and other inert materials.
Resinization is used to consolidate fine sands. This procedure is carried out using solutions of hydrochloric acid and urea ash. The compositions are injected into the soil using special injectors.
Silication is used to consolidate loess and sandy soil types. To do this, chemical solutions are injected into the soil structure. Typically, compositions based on calcium chloride and sodium silicate are used. As a result, it is possible to obtain a silicic acid gel, which makes the soil durable and waterproof.
Thermal
This type of consolidation is based on the combustion of fuel, which is carried out in wells made in the ground. In this case, different fuels can be used - liquid or gaseous.
To consolidate weak soils with high moisture content, it is permissible to use artificial freezing. This method is considered universal and is highly reliable.
The essence of this procedure lies in the fact that coolant is passed through a system of wells. It has a low temperature and takes heat from the soil. As a result, it transforms into an ice-soil massif. It is characterized by a high degree of strength and complete waterproofness.
Freezing can have different types - it all depends on the type of coolant. Thus, there are the brine method and the method using liquefied gas. In the first case, a concentrated solution of calcium or sodium chloride is used. It is first cooled in the evaporator of the refrigeration machine to a temperature of -25 degrees. Liquid nitrogen, freon or ammonia are used as a refrigerant in special devices. In the second case, liquid nitrogen is preferably used. Its evaporation temperature is -196 degrees.
Electric way
This method is suitable for fixing moist clay soil. It involves the use of the effect of electroosmosis. To do this, a direct electric current is passed through the soil. It should have a field strength of 0.5-1 volt per centimeter and a density of 1-5 amperes per square meter. This action allows the clay to dry and compact. As a result, it loses its ability to swell.
There is also an electrochemical method, which differs in that chemical components are added to the soil with current - in particular, calcium chloride. This helps to increase the intensity of soil consolidation.
Mechanical method
This type of fortification is considered the oldest.Its essence lies in the construction of various blocks and structures that help hold layers of soil in place. For this purpose, sheet piling or cantilever fastening can be used.
The first option is considered quite expensive. It is mainly used to develop a recess or depression in earth layers that are saturated with water and located close to the created objects. Sheets must be inserted into the soil layer before excavation begins. If this condition is violated, soil stability will not be achieved.
The console mount has a different device. It is made from special racks or piles. The supporting structures are lowered lower than the planned excavation. Piles hold boards or shields. They take the pressure of the soil.
This method should be used if the excavation is made no more than 5 meters. In case of greater depth, a cantilever-spacer mount must be used. In this case, spacers are installed in the upper fragments of the racks.
Which method is better to choose?
The method of fixing the soil is selected taking into account the type of soil:
- Loess-like and certain types of cover loams and subsidence loess are strengthened by silicatization.
- Resinization is suitable for sandy soil types.
- Cementation is suitable for strengthening large voids. This method of strengthening foundations is also used for fractured rock, gravelly sandy and coarse soil types.
- Drill-mixing consolidation should be used for silts and clays in loamy soil with a fluid consistency.
- Thermal consolidation is suitable for loess-like loams, additive loams, non-subsiding loams and clays.
Consolidation of soil can be done using different methods. Each of them has certain advantages and disadvantages.
