Improve the Ground Techniques
Construction of structures requires establishing foundations of varying size, and geotechnical construction method depends on the firmness of the soil conditions. The existence of unstable grounds for supporting construction structures necessitates the mechanisms to rectify the situation before constructing the structures. There are many techniques to improve the ground conditions if unsuitable for the proposed structure. The paper explores the various categories and methods of ground improvement for construction purposes.
The first category is soil improvement without admixtures, which is widely used for enhancing the stability of the ground before geotechnical construction. Soil replacement is the primary technique of soil improvement under this category, and it is cited as the oldest and simplest ground improvement mechanism (Gaafer, Bassioni, & Mostafa, 216). The foundation of buildings is enhanced by replacing the poor soil with more competently stable materials, including sand, crushed stones, and gravel, among others. Soil replacement help increases soil bearing capacity and reduces consolidation settlement, especially under shallow foundations. The second ground improvement method under this category is precompression, also known as a preloading technique, which entails placing a surcharge fill on top of consolidation settlement before building the structure. It works effectively in clay soil because it has low permeability making the needed consolidation take longer to be attained even a very high surcharge load. Thirdly, the Vertical Drains technique where the drains are installed under a surcharge load to increase drainage that speeds up consolidation. It helps to reduce the period of consolidating clay soil from a few years to months. Common types of vertical drains include sand drains, which involves drilling holes via the clay layer then the holes are filled with sand. The other is prefabricated vertical drains, which are also known as wick drains consisting of channeled synthetics core wrapped in geotextile fabric, particularly in clayey and salty sand.
The second category is soil improvement with admixtures or inclusions is famously described as “in-situ densification” as the outcome in the soil entails the densification of the natural soil existing in the construction site. The ground improvement strategy in this category is stone columns and sand compaction piles. Stone columns are deployed in cohesive soils to boost shear soil strength and minimize excessive settlement and increase the speed of consolidation by shortening horizontal drainage routes for pore-water flow.
The third category is soil improvement using stabilization with additives and grouting methods, which target to enhance soil strength reduces soil compressibility through binding soil particles together. Chemical stabilization is the first technique under this category, which entails mixing chemicals and compacting the soil and wait for a chemical reaction to attain the required outcome. It includes cement stabilization, where cement is used to bind the soil together. Soil lime stabilization is used to stabilize clay soil using soil pH regulation to the range of 5 to 10% (Gaafer, Bassioni, & Mostafa, 219). The other method is fly-ash stabilization because it has little Cementous properties as compared to lime. Also, deep mixed columns that involve soil stabilization a considerable depth using situ ground modification technology. This technique is closely related to the stone columns method. Jet grouting is another soil stabilization method that is considered highly effective across a wide range of soils.
The next category is soil improvement using thermal methods, including heating and freezing, to stabilize the ground before commencing the construction of structures. Heating the soil is one of the thermal ways that are very effective in clay soil and other fine particle soil types. It is critical in strengthening the ground and minimizing soil moisture content as heating increases the evaporation rate. It is useful when the abundant and cheap source of heat is located close to the construction site. The other thermal method of ground improvement is soil freezing to freeze the moisture and pore water in the land to act as a cementing agent in the earth. It is more effective on a wide range of soil types as compared to heating.
Conclusively, soil improvement techniques have been found to help in increasing soil bearing capacity that comes at a cost incorporated in constructing a structure’s foundation. Soil improvement is critical to ensure the construction of buildings and structures on safe and stable ground to bear the weight of the composition. The various ground improvement techniques have been covered above in this article.
Work Cited
Gaafer, Manar, Hesham Bassioni, and Tareq Mostafa. “Soil improvement techniques.” International Journal of Scientific & Engineering Research 6.12 (2015): 217-222.