Modification of black cotton soils by chemical admixtures is a common method for stabilizing the swell-shrink tendency of expansive soils. Advantages of chemical stabilization are that they reduce the swell-shrink tendency of the expansive soils and also render the soils less plastic. Among the chemical stabilization methods for expansive soils, lime stabilization is most widely adopted method for improving the swell-shrink characteristics of expansive soils. Lime stabilization of clays in field is achieved by shallow mixing of lime and soil or by deep stabilization technique. Shallow stabilization involves scarifying the soil to the required depth and lime in powder or slurry form is spread and mixed with the soil using a rotovator. The use of lime as deep stabilizer has been mainly restricted to improve the engineering behaviour of soft clays Deep stabilization using lime can be divided in three main groups: lime columns, lime piles and lime slurry injection. Lime columns refer to creation of deep vertical columns of lime stabilized material. Lime piles are usually holes in the ground filled with lime. Lime slurry pressure injection, as the name suggests, involves the introduction of a lime slurry into the ground under pressure. Literature review brings out that lime stabilization of expansive clays in field is mainly performed by mixing of lime and soil up to shallow depths. The use of lime as deep stabilizer has been mainly restricted to improve the engineering behaviour of soft clays. Use of lime in deep stabilization of expansive soils however has not been given due attention. There exists a definite need to examine methods for deep stabilization of expansive soils to prevent the deeper soil layers from causing distress to the structures in response to the seasonal climatic variations. In addition, there exists a need for in-situ soil stabilization using lime in case of distressed structures founded on expansive soil deposits. The physical mixing of lime and soil in shallow stabilization method ensures efficient contact between lime and clay particles of the soil. It however has limitation in terms of application as it is only suited for stabilization of expansive soils to relatively shallow depths. Studies available have not compared the relative efficiency of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soils. To achieve the above objectives laboratory experiments are performed that study: 1. the efficacy of lime piles in stabilizing compacted black cotton soil specimens from Chitradurga District in Karnataka. The efficiency of lime piles in chemically stabilizing the compacted black cotton soil mass was investigated as a function of: a)amount of lime contained in the lime pile b)radial migration of lime from the central lime pile c)migration of lime as a function of soil depth 2. the relative impact of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soil. The organization of this thesis is as follows After the first introductory chapter, a detailed review of literature performed towards highlighting the need to examine stabilization of expansive soils using lime pile technique is brought out in Chapter 2. Chapter 3 presents a detailed experimental programme of the study. 25 mm and 75 mm diameter lime piles were installed in the compacted soil mass to study the influence of amount of lime contained in the lime pile on the soil properties. The amount of quick lime contained in the 25 mm and 75 mm lime piles corresponded to 1 % and 3 % by dry weight of the soil mass respectively. Radial and vertical migration of lime from the central lime pile was examined by sampling soil specimens at different radial distances from the central lime pile and at different depths of soil sample. At a given depth and radial distance, migration of lime was estimated by comparing the exchangeable cation composition, pH and pore salinity of the treated soil with that of the natural (untreated) black cotton soil specimen. Alterations in the soil engineering properties at a given depth and radial distance were evaluated by comparing the index properties, swell potential and unconfined compressive strength of the lime pile treated soil specimen with those of the untreated specimen. To compare the relative efficiency of lime mixing and lime pile technique in altering the swelling behaviour of black cotton soil, batches of black cotton soil specimens were treated with 1 % and 3 % quick lime on dry soil weight basis. The compacted soil-lime mixes were cured at moisture contents of 31-34 % for a period of 10 days. The physico-chemical, index and engineering properties of the 1 % lime mixed specimens are compared with those of the 25 mm lime pile treated specimens. The properties of the 3 % lime mixed soil specimens are compared with those of the 75 mm lime pile treated specimens. Chapter 4 examines the efficacy of lime piles in stabilizing compacted black cotton soil specimens from Chitradurga District in Karnataka. Experimental results showed that controlling the swell potential of deep expansive soil deposits is possible by the lime pile technique. Treatment with lime pile caused migration of dissociated calcium and hydroxyl ions into the surrounding soil mass. In case of 25 mm lime pile, the experimental setup allowed measurement of migration of lime up to three times the lime pile diameter. In case of 75 mm lime pile, the experimental setup allowed measurement of migration of lime up to 1.6 times pile diameter. In both experiments, migration of lime was also uniform through out the soil depth of 280 mm. Migration of calcium and hydroxyl ions increased the pore salinity and pH of the treated soil mass. The increase in pH caused clustering of additional exchangeable calcium ions at the negative clay particle edges. The increased pore salinity and exchangeable calcium ions reduced the diffuse ion layer thickness that in turn suppressed the plasticity index and the swell potential of the compacted expansive soil. The laboratory results hence bring out that lime pile treatment in the field can substantially reduce the swell potential of the soil at least to a radial extent of 2 to 3 times the lime pile diameter. The 75 mm lime pile contained lime content in excess of the initial consumption of lime (ICL) value of the black cotton soil - namely 2.6 %. Laboratory results showed that migration of hydroxyl ions even from the 75 mm pile could not elevate the soil pH to levels required for soil-lime pozzoIonic reactions (pH ≥12). The very low solubility of lime in water (< 1 g/litre) and the impervious nature of the black cotton soil are considered to have impeded efficient interactions between lime and soil in course of treatment of the expansive soil with lime piles. Absence of soil-lime pozzolonic reactions precluded the formation of cementation compounds in the lime pile treated soil specimens. Cementation compounds formed by the soil-lime pozzolonic reactions are responsible for the much higher strengths of lime stabilized soils. Consequently, treatment with 25 mm pile had no impact on the unconfined compressive strength of the black cotton soil. Comparatively, treatment with 75 mm lime pile slightly increased the strength of the treated soil due to increased inter-particle attraction and particle flocculation. Chapter 5 compares the relative efficiency of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soil. Experimental results showed that mixing of soil and lime promote stronger chemical interactions between lime released hydroxyl ions and clay particles than that achieved by diffusion of lime from a central lime pile. The more alkaline pH of the lime mixed soil specimens rendered the clay particle edges more negative. Consequently, more calcium ions were adsorbed at the clay particle edges of the lime mixed soil specimens imparting them higher exchangeable calcium contents than the lime pile treated soil specimens. Also, at 3 % lime addition, the pH of the lime-mixed soil was sufficiently high (in excess of 12) to cause dissolution of silica and alumina from the clay lattice necessary for the formation of cementation compounds. The stronger lime modification reactions plus the lime-soil pozzolonic reactions (applicable for soil treated with lime content greater than ICL value) achieved by the lime mixing technique rendered the expansive soil much less plastic, much less expansive and much stronger than the lime pile treated specimens. The results of the laboratory study hence suggest that if a choice exists in the field between conventional method of spreading-mixing-compacting of soil-lime mixes and treating the ground with lime piles, the former technique should be adopted because of its greater efficacy in stabilizing the expansive soil. Chapter 6 summarizes the findings of the study.

Expansive or swelling soils, exist in many part of the world, show excessive volume changes with increasing water content. As a result of this volume increase, expansive soils apply vertical and lateral pressures to the structures located or buried in these regions. Many researchs have been carried out on vertical swelling pressures helping to the engineers to design structures withstanding on these stresses. However, lateral swell behaviour of swelling soils have not been fully understood yet. Structures such as / basement walls, water tanks, canals, tunnels, underground conduits and swimming pools which will be built in expansive soils have to be designed to overcome the lateral swelling pressures as well as the other lateral pressures exerted by the soil. For this aim accurate and reliable methods are needed to predict the magnitude of lateral swelling pressures of expansive soils and to understand the lateral swelling behaviour of expansive soils. In this experimental study, the lateral swelling behaviour of an highly expansive clay is investigated using a modified thin wall oedometer which was developed in the METU Civil Engineering Department Soil Mechanics Laboratory earlier. Statically compacted samples were used in constant volume swell (CVS) tests to measure the magnitude of the lateral and vertical swelling pressures. To study the relationship between the lateral and vertical sweeling pressures, they were measured simultaneously. The samples having different initial water contents and different initial dry densities were used to study the effects of these variables on the vertical and the lateral swelling pressures. It is observed that both lateral and vertical pressures increases with increasing initial dry density and they decrease with increasing initial water content. Swell pressure ratio, the ratio of lateral swelling pressure to the vertical one, is increasing with increasing initial water content. Time needed to obtain the magnitude of maximum lateral and vertical pressures decreases with increasing initial water content and increases with increasing initial dry density.

Expansive soils are a worldwide problem that poses several challenges for civil engineers. Such soils swell when given an access to water and shrink when they dry out. The most common and economical method for stabilizing these soils is using admixtures that prevent volume changes. In this study the effect of using rock powder and aggregate waste with lime in reducing the swelling potential is examined. The expansive soil used in this study is prepared in the laboratory by mixturing kaolinite and bentonite. Lime was added to the soil at 0 to 9 percent by weight. Aggregate waste and rock powder were added to the soil at 0 to 25 percent by weight. Grain size distribution, Atterberg limits and swell percent and rate of swell of the mixtures were determined. Specimens were cured for 7 and 28 days. This method of treatment caused a reduction in the swelling potential and the reduction was increased with increasing percent stabilizers.

Les matériaux argileux sont soumis aux chemins complexes de succion/contrainte qui se manifestent par des désordres affectant principalement les structures construites en surface et les ouvrages enterrés. Dans ce contexte, il est important d’appréhender le comportement hydromécanique de ces matériaux afin de mieux maîtriser leur utilisation. Le comportement hydromécanique complexe des matériaux argileux est directement relié à leur structure interne qui a été le principal sujet de plusieurs études sur la micro- et macrostructure des sols. Ces études ont conduit aux développements des modèles élastoplastiques pour sols gonflants. Les modèles existants sont capables de simuler le comportement principal de sol gonflant non saturé, mais ils présentent un grand nombre de paramètres, ce qui prend du temps pour le calcul. Par conséquence, on propose une méthode simplifiée pour modéliser le comportement hydromécanique des sols gonflants basée sur la théorie de l’état limite. Ce modèle est tout d’abord validé par les résultats de l’essai oedométrique. Ensuite, il est implanté dans un code aux éléments finis (CAST3M) pour simuler le comportement in situ des sols gonflants. Enfin, l’application de la théorie de l’état limite au sol gonflant avec une grande densité est effectuée par la combinaison de l’écrouissage cinématique et l’écrouissage isotrope. / Clayey materials are often subjected to the complex suction/stress paths, causing many problems in both surface structures and buried structures built on them. In this context, it is important to study the hydromechanical behavior of these materials in order to better control their use in civil engineering. The complex hydromechanical behavior of clay materials is basically connected to their fabric which has been the main subject of several studies on the micro- and macrostructure of soils. These studies have led to the development of elastoplastic models for expansive soils. The existed models are able to simulate the basic behavior of unsaturated expansive soil, but present a large number of model parameters, leading to a time-consuming calculation. Therefore, we propose a simplified method to model the hydromechanical behavior of expansive soils based on shakedown concept. This model is first validated by the experimental results of cyclic suction-controlled oedometer tests. Then, it is implemented in a finite element code (CAST3M) to simulate the in-situ behavior of expansive soils. Finally, the application of shakedown theory to heavily dense expansive soils is carried out by considering a combined hardening plasticity.

Several geotechnical processes can only be reliably interpreted by taking account of the soil-atmosphere interactions. This thesis investigates two geotechnical problems involving soil-atmosphere interactions that drive water flow through the soil skeleton in two opposite directions; Problem 1: slope failure in expansive soils induced by water infiltration, Problem 2: large strain consolidation of soft soils induced by water evaporation. Both problems are of practical interest for safe and economical design of various geotechnical infrastructures. Two major geotechnical activities in the world; namely, the construction of water transfer canal in expansive soil area in China and the deposition of oil sands and hard rock tailings in Canada can be cited as classic examples of Problems 1 and 2, respectively. In such problems, substantial zones of the domain may switch between an unsaturated and saturated condition. Therefore, rational analysis requires simultaneous modelling of both unsaturated and saturated soil behaviour. The first goal of this thesis is to investigate the influence of swelling (the most characteristic behaviour of expansive soils) on slope stability using numerical methods. Swelling of expansive soils contributes to slope instability during rainfall because of two key reasons (i) soil swelling affects the flow process that actually induces swelling, (i.e. a typical coupling phenomenon), and (ii) swelling-induced stress redistribution and displacement development. In this thesis, the first effect is studied by a coupled (mechanical-hydraulic) numerical analysis of the response of a slope to rainfall using commercial software (GeoSlope). The second effect, the swelling-induced stress redistribution and displacement development after wetting, is tracked using a newly developed numerical program. In the program strain softening behaviour is introduced into the elasto-plastic Mohr-Coulomb Model for modelling unsaturated soil. A novel stress (net stress and suction)-dependent model for moduli of elasticity, combined with the predictive model for shear strength based on Soil Water Retention Behaviour are incorporated into the numerical program to achieve a smooth transition between saturated and unsaturated states. The results show that soil swelling can decrease the factor of safety by accelerating the wetting front depth due to hydro-mechanical coupling, while changes of sliding mass geometry has a negligible influence. The change of stress regime associated with soil swelling is significant to induce plastic strain softening (swelling-induced softening) and contribute to the slope failures. The second goal of thesis is to develop a novel computer program for simulation of large strain consolidation of soft soil under both self-weight and evaporation conditions. This program is both theoretically sound and practically applicable. Several basic/advanced constitutive models for unsaturated soils, including State Surface Model (SSM), Barcelona Basic model (BBM), Glasgow Coupled model (GCM) and bounding surface water retention model, are innovatively implemented into a piece-wise linear framework solved using finite difference technique. The developed program is referred to as UNSATCON-(ML), which has been tested using (a) existing analytical/numerical solutions and (b) various laboratory and field studies for single-layer and multiple-layer deposition of hard rock and oil sands tailings. Features of UNSATCON-(ML) that are improvements over existing models typically used to analyze consolidation-desiccation in soft soils include: (i) coupling of soil large deformation with true unsaturated water flow; (ii) correct reproduction of the shrinkage behaviour of soil under evaporation-induced desiccation; (iii) smooth transition between saturated and unsaturated states despite that some selected models are established using two independent stress variables, (iv) ensuring strictly mass conservation of water, and (v) simulation of irrecoverable volume change and hydraulic hysteresis to properly analyze multilayer tailings deposition. A number of hypothetical field case analyses are carried out using UNSATCON-ML, illustrating its applicability to industry.

La expansividad de suelos es un fenómeno ampliamente reconocido, al cual se le atribuye una copiosa cantidad de problemas estructurales suscitados a nivel mundial. Precisamente, la incidencia de su comportamiento en los antecedentes históricos registrados, propició una marcada tendencia científica por estudiar los factores desencadenantes, así como encontrar técnicas y/o materiales eficientes para su estabilización. En ese afán, la presente investigación pretende evaluar la contribución del cloruro de potasio en el comportamiento expansivo de suelos arcillosos de alta plasticidad. Para ello, se efectuaron ensayos de identificación mineralógica, caracterización física y determinación del grado de expansión, obteniendo como principal resultado una significativa reducción de los parámetros expansivos del suelo. / Soil swelling is a widely known problem, which is related to a huge number of structural problems all over the world. In fact, due to its negative behavior in structures, which have been recorded many times in preceding documents, experts have focused their aim on studying the factors that made expansive soils extremely dangerous, as well to find techniques and/or materials that assure the efficiency of their stabilization. In that commitment, this investigation pretends to evaluate the effects of potassium chloride in the expansive behavior of high-plasticity clay soils. For this purpose, mineralogical identification, physical characterization and degree of expansion determination tests were made, the results of which mainly express a significant reduction of the swelling characteristics of this type of soils. / Trabajo de investigación

La expansividad de suelos es un tema que ha generado sumo interés entre los especialistas geotecnistas dada la incidencia de su comportamiento en los daños estructurales experimentados históricamente a nivel mundial. Al respecto, numerosos estudios han centrado el foco de su investigación en evaluar la contribución de ciertos aditivos químicos sobre las propiedades de desempeño de los suelos problemáticos en materia, sumiéndose en una búsqueda constante de materiales alternativos sostenibles y eficientes para su estabilización. En este contexto, el presente proyecto de investigación se enfoca en evaluar el efecto de la adición de un agente estabilizador, como el cloruro de potasio KCl, en el grado de expansión de suelos arcillosos con alto potencial de hinchamiento en la Urb. Los Vencedores 2da Etapa, en la ciudad de Talara. Para este fin, se realizaron, en primera instancia, ensayos de identificación mineralógica y caracterización física para una muestra inalterada en bloque (Mib) extraída de la zona de estudio. Adicionalmente, se efectuaron ensayos de determinación del potencial de expansión para muestras patrón y grupos posprueba con niveles de presencia de cloruro de potasio en concentraciones de 2%, 4%, 6% y 8% en peso. Los resultados obtenidos demuestran la efectividad del agente químico propuesto en la inhibición de la expansión de los suelos arcillosos, con un porcentaje de reducción máximo equivalente a 92% para la muestra con 6% de cloruro de potasio, siendo esta la concentración óptima. / The issue of the swelling soils has generated a significant interest among the specialists in geotechnics given the incidence of its behavior in the structural damages ever experienced in history. In this regard, multiple studies have focused their research on evaluation of the contribution of some chemical additives in the development of properties of problematic soils in matter, getting into a constant search of alternative sustainable and efficient materials for its stabilization. In this environment, the present project focuses on evaluate the effect on the addition of a stabilizing agent, like potassium chloride (KCl), in the expansion rate of clayey soils with high swelling potential in “Urb. Los Vencedores 2da Etapa, Talara”. For that purpose, there has been made, for instance, mineralogical identification and physical characterization tests for an unspoilt sample in bulk extracted from the study area. In addition, there were made tests to determinate the swelling potential for pattern samples plus post-tests groups with potassium chloride presence in 2%, 4%, 6% and 8% concentration. Results shown that the chemical agent proposed in the inhibition of swelling clayey soils was effective, with a maximum reduction of 92% for the sampling and 6% of potassium chloride, making this concentration the ideal one. / Tesis

Le changement climatique et les événements climatiques sévères tels que les périodes de sécheresse/humidification prolongées sont à l'origine du phénomène de retrait-gonflement dans les sols argileux. Ce phénomène est affecté par les interactions sol-végétation-atmosphère (SVA) et peut causer d’importants dommages structurels aux constructions légères telles que les bâtiments résidentiels. L’objectif de ce travail de recherche est de modéliser le comportement in situ du retrait-gonflement des sols gonflants dans un contexte SVA en se basent sur des outils numériques. Une méthode d'interaction sol-atmosphère est initialement présentée accompagnée d’un modèle couplé hydro-thermique du sol. Cette approche a été principalement mise en place afin de déterminer les conditions aux limites temporelles à la surface du sol en se basent sur la notion du bilan de masse et d'énergie pour déterminer a posteriori, les modifications spatio-temporelles de la succion du sol, de la teneur en eau et de la température. Cette approche a été validée à l'aide des observations in situ des sites instrumentés. Par la suite, l’influence de l’absorption d’eau par les végétations a été intégrée dans le terme source de l’écoulement de l’eau dans un milieu non saturé, à l’aide d’un modèle d’absorption d’eau de racine existant.Les variations temporelles de succion ont été postérieurement reliées au comportement volumique du sol en appliquant une approche simple développée à partir des résultats expérimentaux des essais de séchage/humidification réalisés dans la littérature. Les indices associés dans le plan indice des vides-log succion, ainsi que les paramètres complémentaires du modèle linéaire ont été corrélés aux paramètres géotechniques de base. L'approche proposée a été ultérieurement validée avec des données in situ fournies par la surveillance d’un site expérimental. Le site expérimental de Roaillan a été instrumenté afin de surveiller les modifications physiques du sol ainsi que le comportement structurel du bâtiment. Les comparaisons entre les résultats de la modélisation et les observations in situ de la succion du sol, la teneur en eau, la température et les mouvements du sol dans le temps ont montré une performance acceptable du modèle. L’approche a ensuite été appliquée pour étudier l’influence des projections climatiques futures (2050) sur les variables physiques et les mouvements du sol sur ce site. Trois scénarios RCP relatifs aux changements climatiques ont été examinés dans cette étude, qui ont révélé des différents comportements possibles à court terme et à long terme. Finalement, l'approche développée a été appliquée au territoire français en le divisant en six régions climatiques. Différents paramètres de sol ont été attribués à chacune de ces régions climatiques afin de définir les conditions de référence. En conséquence, l’influence de différents facteurs externes sur les mouvements du sol a été analysée sur une période donnée. Enfin, l’étude suggère les mesures adéquates à prendre pour minimiser l’amplitude du phénomène de retrait et de gonflement dans un contexte SVA. / Climate change and severe climatic events such as long drought/rehydration periods are at the origin of the shrinkage and swelling phenomenon in expansive soils. This phenomenon is affected by Soil-Vegetation-Atmosphere (SVA) interactions and can cause severe structural damage to lightly loaded constructions such as residential buildings. The objective of this re-search work is to simulate the in-situ behavior of the shrinkage-swelling in expansive soils in a SVA context using numerical tools. A soil-atmosphere interaction method is primarily presented along with a coupled hydro-thermal soil model. This approach was established in order to determine primarily, the natural time variable boundary conditions at the considered soil surface based on the mass and energy balance concept, and secondly to determine the spatial-temporal changes of the soil suction, water content and temperature. This approach was validated using in situ observations of monitored sites. Thereafter, the influence of the water uptake by vegetation was incorporated in the source term of the unsaturated water flow theory, using an existing root water uptake model. Subsequently, the temporal variations of the soil suction were related to the volume change behavior using a simple approach developed based on the experimental results of drying/wetting tests performed in the literature. The associated volumetric indices in the void ratio-log suction plan, along with the complementary parameters of the linear model were correlated with basic geotechnical parameters. The proposed approach was validated with in situ data provided from an experimental site. The Roaillan experimental site was instrumented in order to monitor the soil’s physical changes along with the structural behavior of the building. Comparisons between the simulated and observed soil suction, soil water content, temperature and soil movements in time and depth showed an acceptable performance of the predictions. The approach was then extended to study the influence of future climate projections (2050) on the soil’s physical variables and movements. Three RCP climate change scenarios were considered in this analysis which revealed different possible behavior in both short term and long term. Finally, the developed approach was applied to the French territory by dividing it to six different climatic regions. Different soil parameters were attributed to each of these climatic regions in order to set the reference condition. Thereafter, the influence of different external factors was analyzed on the soil movements over a chosen period. The study finally suggests the adequate actions to take for minimizing the amplitude of the shrinkage and swelling phenome-non in a SVA context.

During a survey of black cotton soil zones of Karnataka, indigenously stabilized black cotton soil deposits were encountered in Belgaum, Bijapur, Bagalkot and Gadag Districts of Karnataka. These modified black cotton soils have low swelling and negligible shrinkage tendencies. Owing to their low volume change potential on moisture content changes, these soils are widely preferred in earth construction activities. The exact origin of these modified black cotton soil deposits is not known. According to anecdotal references, these soils were prepared by mixing unknown proportions of wood ash, organic matter and black cotton soil and allowing them to age for unknown periods of time. As wood-ash was apparently used in their preparation, these modified black cotton soils are referred to as ash-modified soils (AMS) in the thesis. The practice of preparing ash-modified soils is no longer pursued in black cotton soil regions of Karnataka and the available supply of this indigenously stabilized soil is being fast depleted. Also, attempts have not been made to characterize the physico-chemical and engineering properties of AMS deposits of Karnataka. Given the widespread utilization of ash-modified soils in black cotton soil areas of Karnataka, there is a need to understand their physico-chemical and engineering behaviour and the physico-chemical mechanisms responsible for their chemical modification. Swelling and shrinkage of expansive soil deposits are cyclic in nature due to periodic climatic changes. Chemically stabilized black cotton soil deposits are also expected to experience cyclic wetting and drying due to seasonal climatic changes. The impact of cyclic wetting and drying on the swelling behaviour of natural expansive soils is well-documented. However, the impact of alternate wetting and drying on the swelling behaviour of admixture stabilized expansive soils (these include natural - ash-modified soils and laboratory - lime stabilized black cotton soils) has not been examined. Such a study would be helpful to assess the long term behaviour of admixture stabilized soils in field situations. To achieve the above objectives, experiments are performed that study: 1.The physico-chemical and engineering properties of ash-modified soils from different Districts of Karnataka. The physico-chemical and engineering properties of natural black cotton soil (BCS) specimens from locations adjacent to ash-modified soil deposits are also examined to understand and evaluate the changes in the engineering characteristics of the ash-modified soils due to addition of admixtures. 2. Identify the physico-chemical mechanisms responsible for the chemical stabilizationof ash-modified soils. 3.The influence of cyclic wetting and drying on the wetting induced volume changebehaviour of admixture stabilized black cotton soils, namely, ash-modified blackcotton soils and lime stabilized black cotton soils.

Los resultados del estudio que se expone en la presente tesis, tratan sobre las arcillas expansivas en “Talara”, en base a resultados obtenidos en los ensayos de laboratorio como el Análisis Granulométrico por Tamizado, ensayo de Límite Líquido, Límite Plástico e Índice de Plasticidad, ensayo de Proctor modificado y el ensayo Corte Directo. Cabe decir que dichos ensayos se realizaron tomando como punto de partida las características geológicas, geomorfológicas, geotécnicas y la evaluación de daños en las diversas estructuras de la zona como viviendas producto de la expansión y consolidación del terreno. La problemática se origina a raíz del suelo arcilloso, ya que la principal característica que puede tener ese tipo de suelo es que sea un suelo expansivo, por lo tanto, se debe tener en consideración mejorar el suelo para evitar posteriormente daños estructurales. En la investigación se describirán las principales consecuencias y factores que intervienen en el fenómeno de la expansión y el cómo enfrentar a este tipo de suelo. El presente estudio busca la mejora del suelo mediante una técnica innovadora, eco amigable y factible como es la estabilización física usando el vidrio reciclado y las fibras de polipropileno (materiales de desecho en las operaciones de la construcción), ya que en la actualidad estos dos tipos de materiales generan un impacto negativo en el medio ambiente, por lo cual se trata de reutilizar dichos materiales en el mejoramiento del suelo. El estudio se basó en una muestra de suelo medianamente expansivo, debido al registro del Límite Líquido, Límite Plástico e Índice de Plasticidad, extraído de la Urbanización Sudamérica, localizado en Talara, Piura con el fin de mejorarlo, para luego verificar el comportamiento de mejora de las propiedades de resistencia al corte del suelo. Como parte del desarrollo de la investigación se realizaron los diversos ensayos para comprobar con datos numéricos la mejora del suelo, otorgando porcentajes de sustitución con respecto al peso seco (0%, 5%, 6% y 7.5%) a la muestra en estado natural. Finalmente, se obtuvieron las mejoras de las propiedades de resistencia al corte con un porcentaje de sustitución equivalente a 5%, el cual registra las mejoras en cohesión y ángulo de fricción. / The results of the study that is presented in this thesis, deals with the expansive clays in "Talara", based on results obtained in laboratory tests such as the Granulometric Analysis by Screening, Liquid Limit test, Plastic Limit and Plasticity Index, modified Proctor test and the Direct Cut test. It is possible to say that these tests were carried out taking as a starting point the geological, geomorphological, geotechnical characteristics and the evaluation of damages in the different structures of the area as houses product of the expansion and consolidation of the land. The problem originates from the clay soil, since the main characteristic that this type of soil can have is that it is an expansive soil, therefore, it is necessary to consider improving the soil to subsequently avoid structural damage. The research will describe the main consequences and factors involved in the phenomenon of expansion and how to deal with this type of soil. The present study seeks to improve the soil through an innovative, eco-friendly and feasible technique such as physical stabilization using recycled glass and polypropylene fibers (waste materials in construction operations), since these two are currently Types of materials generate a negative impact on the environment, so it is about reusing these materials in soil improvement. The study was based on a sample of moderately expansive soil, due to the registry of the Liquid Limit, Plastic Limit and Plasticity Index, extracted from the South American Urbanization, located in Talara, Piura in order to improve it, and then verify the improvement behavior of the properties of resistance to the cut of the floor. As part of the development of the research, the various tests were carried out to verify the improvement of the soil with numerical data, granting replacement percentages with respect to dry weight (0%, 5%, 6% and 7.5%) to the sample in its natural state . Finally, the improvements of the properties of resistance to the cut with a percentage of substitution equivalent to 5% were obtained, which records the improvements in cohesion and angle of friction. / Tesis