abstract: The experience base of practitioners with expansive soils is largely devoid of directly measured soil suction. This historical lack of soil suction measurement represents an impediment to adoption of modern unsaturated soil engineering to problems of expansive soils. Most notably, soil suction-based analyses are paramount to proper design of foundations in expansive soils. Naturally, the best method to obtain design suction profiles is to perform an appropriate geotechnical investigation that involves soil moisture change-appropriate drilling depths, sampling intervals, and requisite laboratory testing, including suction measurement. However, as practitioners are slow to embrace changes in methodology, specifically regarding the adoption of even relatively simple suction measurement techniques, it has become imperative to develop a method by which the routine geotechnical procedures currently employed can be used to arrive at acceptable approximations of soil suction profiles. Herein, a substitute, or surrogate, for soil suction is presented, such that the surrogate agrees with observed field soil suction patterns and provides estimates of soil suction that are acceptable for use in practice. Field investigations with extensive laboratory testing, including direct suction measurement, are used in development of the soil suction surrogate. This surrogate, a function of water content and routinely measured soil index properties, is then used in estimation of field expansive soil suction values. The suction surrogate, together with existing geotechnical engineering reports, is used to augment the limited existing database of field soil suction profiles. This augmented soil suction profile database is used in development of recommendations for design suction envelopes and design suction profiles. Using the suction surrogate, it is possible to proceed from the beginning to the end of the Suction-Oedometer soil heave/shrinkage analysis without directly measuring soil suction. The magnitude of suction surrogate-based heave estimates is essentially the same as heave estimates obtained using direct soil suction measurements. The soil suction surrogate-based approach, which uses a complete-stress-state approach, considering both net normal stress and soil suction, is an intermediate step towards the adoption of unsaturated soil engineering in expansive soils analyses, wherein direct soil suction measurements are routinely made. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2019

Submitted by Erika Demachki (erikademachki@gmail.com) on 2015-04-20T17:51:20Z No. of bitstreams: 3 Dissertação - Melina Freitas Rocha - 2013 - parte 01.pdf: 18877116 bytes, checksum: db6e237169520b45aaf7353c708c8366 (MD5) Dissertação - Melina Freitas Rocha - 2013 - parte 02.pdf: 8252606 bytes, checksum: c0d1163233c3716f97b6b48d0006dada (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2015-04-20T17:52:46Z (GMT) No. of bitstreams: 3 Dissertação - Melina Freitas Rocha - 2013 - parte 01.pdf: 18877116 bytes, checksum: db6e237169520b45aaf7353c708c8366 (MD5) Dissertação - Melina Freitas Rocha - 2013 - parte 02.pdf: 8252606 bytes, checksum: c0d1163233c3716f97b6b48d0006dada (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-04-20T17:52:47Z (GMT). No. of bitstreams: 3 Dissertação - Melina Freitas Rocha - 2013 - parte 01.pdf: 18877116 bytes, checksum: db6e237169520b45aaf7353c708c8366 (MD5) Dissertação - Melina Freitas Rocha - 2013 - parte 02.pdf: 8252606 bytes, checksum: c0d1163233c3716f97b6b48d0006dada (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-07-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The need for the use of structures retaining wall have been increasingly used in engineering works. The valuation of soil use has led to wide-ranging exploration of the subsoil, resulting in large excavations that change the equilibrium state of the soil. The performance and design of retaining wall require a good understanding of the stress state of the soil, soil-structure interaction and varying the saturation of soil during construction and useful life. The useful life of retaining wall must ensure stability, functionality and durability. The analysis of soilstructure interaction becomes important by the fact that the same structure subjected to the same external load, presents support reactions that vary with the particular conditions of the mass of soil in which it lies. Therefore the study of soil-atmosphere interaction is an essential factor for unsaturated soils. In order to evaluate the influence of suction on structural design in balance were simulated real conditions of rainfall in three different soils for three excavations (3, 6 e 9 m) and inciciais different conditions N.A. It was observed that the behavior of the suction profile is inwardly related to the parameters as well as saturated and unsaturated soil each, with the intensity and duration of precipitation. Through the theory of earth pressure Rankine for saturated soils, the formulation was developed to calculate the active and passive earth pressure into account the unsaturated soil for three different behaviors of suction, i.e., constant suction over the depth matric suction decrease linearly with depth and suction profile mixed (ie, the part is kept constant and decrease linearly with depth). After determination of the active and passive earth pressure was established equilibrium limit retaining wall and give the sheet length for safety factors of 1,0 and 1,5. It was noticed that there is reduction in the active earth pressure and increased passive earth pressure for all conditions in suction profile. Due to suction, there is an increased horizontal depth tension zone that contributes to the reduction in the horizontal efforts on the structures retaining wall , then a reduction in the sheet length. Otherwise the specific weight natural varies with the suction and that is a factor that can increase efforts, particularly for rainfall with relative intensity close to 1 (q/ksat) and saturated soils with high permeability, where suction is small and has constant distribuiton in the soil profile. / A necessidade do uso das estruturas de contenção tem sido cada vez mais frequente em obras de engenharia. A valorização do uso do solo tem levado a exploração ampla do subsolo, implicando em grandes escavações que alteram o estado de equilíbrio do solo. O desempenho e dimensionamento da contenção exigem um bom entendimento do estado de tensões do solo, da interação solo-estrutura e da variação da saturação do solo durante a construção e vida útil da contenção. A vida útil de uma obra deve garantir estabilidade, funcionalidade e durabilidade. A análise da interação solo-estrutura torna-se importante pelo fato de que a mesma estrutura, submetida à mesma carga externa, apresenta reações de apoio que variam com as condições particulares do maciço de solo em que ela se encontra. Portanto o estudo da interação solo-atmosfera é um dos fatores essenciais para os solos não saturados. Com intuito de avaliar a influência da sucção no dimensionamente de uma estrutura de contenção em balanço, foram simulados condições reais de precipitações em três solos distintos para três profundidades de escavações (3, 6 e 9 m) e para várias condições inciciais de N.A. E observou-se que o comportamento do perfil de sucção está intimamente relacionado com os parâmetros saturados bem como os não saturados de cada solo, com a intensidade e duração da precipitação. Através da teoria do empuxo de terra de Rankine, para os solos saturados foram desenvolvidas as formulação para cálculo dos empuxos ativos e passivo levando em consideração a não saturação do solo, para três comportamentos diferentes da sucção, isto é; sucção constante ao longo da profundidade, sucção variando linearmente com a profundidade e perfil de sucção misto (i.e., parte é mantido constante e parte varia linearmente com a profundidade). Após a determinação dos empuxos ativo e passivo foi estabelecido o equilíbrio limite da contenção e determinado o comprimento da ficha para dos fatores de segurança de 1,0 e 1,5. Percebeu-se que há redução do empuxo ativo e um acréscimo do empuxo passivo para todas as condições de perfil de sucção. Devido a sucção, há um aumento da profundidade da tensão horizontal nula que foi um dos parâmetros que contribui para a redução dos esforços horizontais na contenção, logo uma redução no comprimento da ficha. Por outro lado o peso específico natural varia com a sucção e esse é um fator que pode aumentar os esforços, principalmente para chuvas com intensidade relativa próxima de 1 (q/ksat) e solos com permeabilidade saturada alta, onde a sucção é pequena e tem-se distribuição constante no perfil do solo.