CHAPTER ONE

INTRODUCTION

1.1 Background to the study

Structures built on unstable ground frequently require soil improvement to ensure the safety and stability of surrounding buildings. Numerous techniques, including vibro-floatation, compaction piles, compaction with explosives, excavation and replacement, grouting, and so forth, can be used to enhance the ground in granular soils. The choice of the best approach depends on a number of variables, including the site’s characteristics, the amount of compaction needed, the kinds of structures to be supported, the amount of time available to finish the project, the availability of tools and materials, etc. In particular, soil compaction is helpful in minimizing overall settling in sand and can provide practical solutions for a variety of foundation issues. The majority of soil particles in sandy soil have a diameter greater than 2 mm. Its low nutrient-holding capacity and good water drainage are its main characteristics. It is difficult for sandy soil to retain rainwater. It is granular and made up of tiny pieces of rock and mineral. As a result, the texture is grittier and is created by rocks including shale, granite, quartz, and limestone weathering and disintegrating. It is also simpler to cultivate if it has a lot of organic matter, but this also permits more drainage than is necessary. This causes the plant to overdrain and become dehydrated in the summer. It warms very quickly in the spring. Conversely, grouting is the process of injecting a solution or suspension of stabilizers into the soil below the surface. When you scrape sandy dirt, the biggest particles are felt to be scratchy. This is due to the fact that it lacks nutrients and has sharp edges.

The term “solubilization” refers to a phenomena in which a partially or fully saturated soil gradually loses its firmness and stiffness in reaction to an applied stress, typically the shaking of an earthquake or another abrupt shift in the stress situation, making the soil behave more like a liquid. For the geotechnical community and those engaged in the construction and development of structural foundations, liquefaction is a major concern. Ground enhancement techniques are frequently employed to enhance subsurface qualities, such as drainage, settlement characteristics, shear strength, and bearing capacity (Sanaz Sayehv and et al., 2012). There are various grouting methods namely: compacting grouting, permeation grouting and jet grouting. I will be using the permeation grouting. The term ground improvement and ground modification is said to be the improvement or modification in the engineering properties of the soil that are carried out at a site where the soil in its natural state does not process properties that are adequate for the proposed civil engineering activity. Ground improvement is referred to as any procedure undertaken to increase the shear strength, reduce the permeability and compressibility or render the physical properties of soil more suitable for projected engineering use. A large number of soil improvement technic has been developed over the years which includes drainage, compaction, Preloading, reinforcement, grouting, electrical. Chemical or thermal methods. Among the various soil stabilization procedure, the most suitable one is selected depending upon the type of soil available, time, and cost involved.

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 selective of the most suitable method meant for the improvement of a particular soil sample depends on various factors such as: specific considerations available time for completion of the project, availability of equipment and soil conditions, required degree of compaction, types of structure to be supported, as well as site materials etc. 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 consist 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.

1.2 AIM AND OBJECTIVE
1.     To determine the nature of the sandy soil particles.
2.     To determine the degree of the sandy soil compatibility.
3.     To carry out the improvement of sandy soil through grouting.
4.     To carryout some laboratory test on sandy soil such as compaction test California bearing ration (CBR) test, atterberg LIMIT test, liquid limit test, Plastic limit test, sieve analysis test in comparing the effectiveness of grouting system.

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