IMPROVEMENT OF BEARING CAPACITY OF SANDY SOIL BY GROUTING
The construction of structure on weak ground often requires the soil to be improved in order to ensure the safety and the stability of surrounding buildings. The ground improvement in granular soils can be achieved by different methods such as vibro-floatation, compaction piles, and compaction with explosives, excavation and replacement, grouting e.t.c. The selective of the most suitable method depend on a variety of factors, such as: soil conditions, required degree of compaction, types of structure to be supported, as well as site specific considerations available time for completion of the project, availability of equipment and materials e.t.c. Soil compaction can offer effective solutions for many foundation problems and his especially useful for reducing total settlement in sand. Sandy soil means most of the soil particles are bigger than 2mm in diameter. It gives good water drainage and has a low capacity to hold nutrients. Sandy soil does not hold moisture very well. It is granular and consists of rock and mineral particle that are very small. Therefore, the texture is gritty and is formed by the disintegration and weathering of rocks such as limestone, granite, quartz and shale. Is also easier to cultivate it if it is rich in organic materials but then it allows drainage more than needed. This results in over drainage and dehydration of the plant in summer. It warms very fast in the spring season. Grouting on the other hand is a process whereby stabilizes either in the form of suspension or solution is injected into sub surface soil. Sandy soil is the largest particle in the soil when you rub it, if feels rough. This is because it has sharp edges and it does not hold many nutrients.
1.1 HISTORICAL BACKGROUND OF GROUTING
The development and history of compaction grouting over the last 30-40 years as been established by many distinguished researcher, design engineer and design contractor. Many technical papers are been published dealing physically with the issues surround compaction grouting design such as: “compaction grouting, 1973”, “planning and performing compaction grouting” 1974. These and other important reference are the main stream basis of knowledge for the highly specialize engineering and construction technique know as compaction grouting. The compaction grout method as some unique features which allow distinct advantages over other remedial method of geo-technical construction. In many distances growth is the only viable solution. Some of the advantages include: Economic: Many time compaction grouting is the only feasible solution to foundation settlement problems, other than demolishing the structure and re-building with expensive deep foundation technique. Minimal disturbance: During the grouting operation, destructure may remain occupied and in service. Minimal risk: Compaction grouting offers minimal risk of catastrophic structural failure while re-leveling structure. Other are: Minimal geotechnical exploration, provide greater support for structures, cost factor e.t.c.