Collapsible soils covers naturally over 10% of the earth’s surface. This makes it a global problem and it is essential that engineers identify and control collapsibility prior to construction. Hence in this thesis, a study on identification, evaluation and control of soil collapsibility is undertaken. Four geologically different soils have been tested at five compactive variables from optimum moisture content (OMC). The soils tested include: Brown inorganic silty clay of low plasticity (A); White inorganic silt with slight plasticity (B); Red inorganic clay of intermediate plasticity (C); and Brown sand-clay mixtures with inorganic clay of low plasticity (D). The soils were each compacted at moisture variations 60% - 80%, 80% - 95%, 95% - 105%, 110% - 125% and 125% - 150% respectively representing ‘Low Dry OMC’, ‘High Dry OMC’, ‘At OMC’, ‘Low Wet OMC’ and ‘High Wet OMC’. The major causes of collapsibility of soil and the geomorphological processes that gives the pedogenesis of collapsible soils, is highlighted and great emphasis is placed on the adverse effect of collapsible soils. The experimental results from particle size distribution, Atterberg, compaction, triaxial and double oedometer tests showed that the soil’s percentage fine with the fines material (silt or clay), coefficient of uniformity, optimum moisture content, Atterberg limits, and stress-strain properties affect the metastability of the soils and they can be compared to the soil’s collapse potential when pressures and moisture content are applied on the soils. Results obtained showed that the soil’s collapse potential is directly proportional to 1) percentage fines, 2) the difference between the silt and clay percentage, 3) the Atterberg limits (liquid limit, plastic limit and plasticity index), and 4) internal friction angle; and inversely proportional to 1) coefficient of uniformity, 2) initial moisture content, 3) cohesion and finally 4) peak deviator stress. Each soil’s geological property proved to have an adverse effect on the metastability of the soils especially the dry of optimum moisture content. The most interesting results were obtained from the oedometer test. Results of the critical pressure varied with each soil and their compactive variable; Most of the soils at their ‘dry OMC’ had the highest collapse potential. In general, the lower the critical pressure the higher the collapse potential of the soil. The experimental data obtained herein were checked with the past research collapse indexes and found the results agreeing with just two research work out of eighteen examinations. Finally models for identifying soil collapsibility are generated with relationship between parameters from sieve, Atterberg, proctor compaction and triaxial. Laboratory data and data from twelve research work were used to verify the models and they show that the models work. After the verification of these formulas with past research data collected, the best models were three compactive variable models. The models give a collapsibility index in terms of percentage fines, initial moisture content, initial degree of saturation and initial dry density.

大體上來說，高維列聯表通常比較不容易分析，因此我們考慮將某柴暫不列入探討之因子的次數相加，以便降低列聯表的維數。但是降低列聯表維數的過程必需相當慎重，以確保合併的過程不致影響到所欲探討之因子間的相關性。本文就 "sun-to-zero" 及 "set-to-zero" 兩種不同的對數線性模式參數之限制式，分別探討簡易合併(collapsibility)、嚴格合併(strict collapsibility)及強固合併(strong collapsibility)之充要條件，並舉例說明及印證這些條件。 / A lower-dimensional contingency is usually easier to understand than a higher-dimensional one. Collapsing a larger table into a smaller one so that the associations among a set of factors can be easier to explain, however, should be exercised with care. In this study, definitions of collapsibility, strict collapsibility, and strong collapsibility are viewed. Distinctions among the three are compared. Necessary and sufficient condittions for these three types of collapsibility under conventional "set-to-zero" and "sum-to-zero" constraints are discussed and proved.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-12-01T14:03:53Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Klayde Versão 9 - revisão final.pdf: 9120386 bytes, checksum: d27cc83b0c7db013e2bf497f74e2a430 (MD5) / Made available in DSpace on 2016-12-01T14:03:53Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação Klayde Versão 9 - revisão final.pdf: 9120386 bytes, checksum: d27cc83b0c7db013e2bf497f74e2a430 (MD5) Previous issue date: 2016-05-05 / CNPQ / A colapsibilidade dos solos é um fenômeno típico de solos porosos, quando saturados apresentam variação de volume, podendo provocar danos significativos nas obras de engenharia, comprometendo total ou parcialmente estas obras. A ocorrência de solos colapsíveis é observado em vários municípios do Estado de Pernambuco, e em particular no Município de Petrolina. A investigação geotécnica e o entendimento de como se processa o fenômeno é imprescindível para a elaboração de projetos e a diminuição de possíveis danos às construções assentadas sobre esse tipo de solo. O objetivo desse trabalho é avaliar a variação de volume e de resistência de ponta com e sem inundação em solo compactado. A variação de volume devido à inundação foi avaliada utilizando ensaios edométricos simples e duplo e a resistência de ponta por meio de penetrômetro estático, em solo de um Conjunto Habitacional do Programa Minha Casa, Minha Vida, localizado no Município de Petrolina-PE, nos graus de compactação de 80%, 85%, 90% e 95% e nas umidades natural (0,22%), 4,00% e 7,00%. O solo é essencialmente arenoso com mais de 90% de sua composição de areia, fração argilosa < 8% e praticamente sem presença de silte. O solo é mau graduado (CU < 5%), não liquido e não plástico, se enquadra no grupo SM (Areia Siltosa) na classificação do SUCS o valor máximo do potencial de colapso atingido nos ensaios edométricos simples foi de 13,41% na tensão de 640 kPa no solo com GC 80% e umidade de 4,00% e o valor mínimo foi de 0,24,00% na tensão de 10 kPa, GC 95% e umidade de 7,00%. Os valores dos potenciais de colapso (CP) diminuem com o acréscimo de umidade inicial e grau de compactação. A sua resistência de ponta cresce com o aumento do grau de compactação, umidade e profundidade, atingindo valor de 19,17 MPa para GC = 95% e umidade 7,00%. Há perda de resistência de ponta durante o processo de inundação que depende da umidade inicial e grau de compactação e há acréscimo, no solo saturado após o colapso. A variação de volume e a resistência de ponta devido à variação de inundação são influenciadas pelo grau de compactação e umidade inicial do solo. / The collapsibility soil is a typical phenomenon of porous soil when saturated present volume variation, which can cause significant damage to the engineering works, committing all or part of these works. The occurrence of collapsible soils is observed in several municipalities in the state of Pernambuco, and in particular in the city of Petrolina. Geotechnical investigation and understanding of how processes if the phenomenon is essential for the development of the project and the reduction of possible damage to buildings settled on this type of soil. The aim of this study is to evaluate the change in volume and tip resistance with flooding in compacted soil. The volume change due to flooding was assessed using single and double oedometric tests and tip resistance through static penetrometer in soil of a housing program of the Minha Casa, Minha Vida, located in the city of Petrolina, in degrees compretion of 80%, 85%, 90% and 95% and the natural moisture (0.22%), 4.00% and 7.00%. The soil is mainly sandy with more than 90% of its sand composition, clay fraction < 8% and virtually no presence of silt. The soil is poorly Graduate (CU <5%), not liquid and not plastic, falls within the SM group (silty sand) in classification SUCS. collapsing the maximum value of the potential in achieving simple oedometric assays was 13.41% at 640 kPa in the ground stress to GC 80% moisture and 4.00% and the minimum value was 0, 24,00% at 10 kPa pressure, GC 95% and humidity of 7.00%. The values of the collapse potential (CP) decrease with the initial moisture increase and degree of compaction. Its tip resistance increases with increasing the degree of compaction, humidity and depth, reaching a value of 19.17 MPa GC = 95% moisture and 7.00%. There is loss of peak strength during the flooding process that depends on the initial moisture content and degree of compaction and there is an increase in the saturated soil after collapse. The volume change and the tip resistance due to flood variations are influenced by the degree of compaction and soil initial moisture.

Mendelian randomization is an epidemiological method for using genetic variationto estimate the causal effect of the change in a modifiable phenotype onan outcome from observational data. A genetic variant satisfying the assumptionsof an instrumental variable for the phenotype of interest can be usedto divide a population into subgroups which differ systematically only in thephenotype. This gives a causal estimate which is asymptotically free of biasfrom confounding and reverse causation. However, the variance of the causalestimate is large compared to traditional regression methods, requiring largeamounts of data and necessitating methods for efficient data synthesis. Additionally,if the association between the genetic variant and the phenotype is notstrong, then the causal estimates will be biased due to the “weak instrument”in finite samples in the direction of the observational association. This biasmay convince a researcher that an observed association is causal. If the causalparameter estimated is an odds ratio, then the parameter of association willdiffer depending on whether viewed as a population-averaged causal effect ora personal causal effect conditional on covariates. We introduce a Bayesian framework for instrumental variable analysis, whichis less susceptible to weak instrument bias than traditional two-stage methods,has correct coverage with weak instruments, and is able to efficiently combinegene–phenotype–outcome data from multiple heterogeneous sources. Methodsfor imputing missing genetic data are developed, allowing multiple genetic variantsto be used without reduction in sample size. We focus on the question ofa binary outcome, illustrating how the collapsing of the odds ratio over heterogeneousstrata in the population means that the two-stage and the Bayesianmethods estimate a population-averaged marginal causal effect similar to thatestimated by a randomized trial, but which typically differs from the conditionaleffect estimated by standard regression methods. We show how thesemethods can be adjusted to give an estimate closer to the conditional effect. We apply the methods and techniques discussed to data on the causal effect ofC-reactive protein on fibrinogen and coronary heart disease, concluding withan overall estimate of causal association based on the totality of available datafrom 42 studies.

1 Topological and Geometrical Combinatorics Martin Tancer Abstract The task of the thesis is to present several new results on topological methods in combinatorics. The results can be split into two main streams. The first stream regards intersection patterns of convex sets. It is shown in the thesis that finite projective planes cannot be intersection patterns of convex sets of fixed dimension which answers a question of Alon, Kalai, Matoušek and Meshulam. Another result shows that d-collapsibility (a necessary condition on properties of in- tersection patterns of convex sets in dimension d) is NP-complete for recognition if d ≥ 4. In addition it is shown that d-collapsibility is not a necessary condition on properties of intersection patterns of good covers, which disproves a conjecture of G. Wegner from 1975. The second stream considers algorithmic hardness of recognition of simplicial com- plexes embeddable into Rd . The following results are proved: It is algorithmically un- decidable whether a k-dimensional simplicial complex piecewise-linearly embeds into Rd for d ≥ 5 and k ∈ {d−1, d}; and this problem is NP-hard if d ≥ 4 and d ≥ k ≥ 2d−2 3 .