L'amélioration des sols est à l'origine une solution économique pour rendre un sol constructible, notamment par rapport aux méthodes de fondations profondes utilisant des pieux. L'amélioration de la compréhension du comportement du matériau provenant de soil-mixing ou jet-grouting connait un intérêt grandissant. Ces deux procédés consistent à mélanger le sol en place avec un liant hydraulique afin de former des colonnes ou des panneaux en "béton de sol". Les fondations spéciales ont connu ces dernières décennies un franc succès aux États-Unis, au Japon et dans les pays Scandinaves. En Europe les nouvelles priorités, pour la plupart liées à l'environnement, au coût de la construction et à la valorisation des matériaux encouragent les industriels à contribuer au développement technologique de la discipline. Certains procédés de mélange paraissent désormais suffisamment sophistiqués pour assurer la réalisation d'éléments structuraux tels que les fondations et les soutènements.Contrairement aux matériaux préfabriqués, à cause des incertitudes liées à l'hétérogénéité des sols, aux conditions environnementales et à la qualité du malaxage sur chantier, il reste toutefois difficile de prédire les propriétés du matériau obtenu. Un manque de règles et de recommandations semble également assez flagrant. Pour répondre au besoin de prédiction et de fiabilisation performantielle des bétons de sol l'objectif des travaux de thèse était donc d'étudier l'influence des paramètres de formulation sur les propriétés physiques et mécaniques du matériau. Les fortes quantités d'eau de gâchage nécessaires à l'obtention d'une consistance de BAP et la faible granulométrie des sols limitent les caractéristiques mécaniques de ces bétons. De par leur composition, les bétons de sol sont donc particulièrement sensibles au retrait de dessiccation et l'importante porosité de ces matériaux les aussi rend plus vulnérables aux agressions chimiques. L’objectif ultime des travaux de recherche était donc de déterminer des paramètres pour une meilleure visibilité de la durée de vie des ouvrages en béton de sol.L'approche béton suivie au laboratoire a consisté à étudier différents bétons de sol composés de sols "artificiels", d'un ciment CEM III/C, et avec un rapport E/C efficace constant. L'étude paramétrique met en évidence un pourcentage volumique d’argile dans le sol au-delà duquel la résistance diminue et la rigidité du matériau peut poser problème pour certaines utilisations structurelles. Les gains de résistance et de rigidité associés à l'augmentation du dosage en ciment sont également quantifiés. Les résultats montrent que l'endommagement par chargement mécanique dépend surtout du dosage en ciment. À partir des résultats expérimentaux, des relations mathématiques sont proposées pour la phase de dimensionnement. Divers essais de vieillissement accéléré permettent de définir des seuils pour les indicateurs de durabilité (porosité et la perméabilité à l'eau). L'analyse de la microstructure du matériau montre aussi l'importance de l'interface pâte-granulat et a permis d'identifier certains mécanismes de dégradation en lien avec les conditions d'exposition. Enfin, ce travail est complété par une étude du comportement à haute température. / Soil improvement initially has been used as an economical solution to make soil constructible, particularly in the context of deep foundation methods using piles. There has been growing interest to improve understanding of the behavior of soil-mixing and jet-grouting material, which consist of mixing the soil in place with a hydraulic binder in order to form columns or panels of "soilcrete". In recent decades, these special foundations have had a great success in the United States, Japan and the Scandinavian countries. In Europe, the environmental consciousness and the ongoing trend to reuse existing material to reduce cost of construction are driving companies to contribute to the technological development of this discipline. Some mixing processes now seem to be sophisticated enough to provide structural elements such as foundations and supports.Unlike prefabricated materials, it is difficult to predict the properties of the material obtained through deep soil mixing due to uncertainties related to soil heterogeneity, environmental conditions and the quality of mixing on site. The objective of the thesis work is to address this need for prediction and performantial reliability of soilcrete by studying the influence of the formulation parameters on the physical and mechanical properties of the material. The high quantities of mixing water necessary to obtain a BAP consistency and the small particle size of the soil limit the mechanical properties of the soilscretes and as a consequence, are particularly sensitive to desiccation shrinkage. Besides, the high porosity of these materials also makes them more vulnerable to chemical aggressions. The ultimate objective of the research is to determine parameters for a better visibility of the lifetime of concrete structures in the soil.The approach tested in the laboratory consists of studying different soilcretes composed of "artificial" soils, CEM III / C cement and with a constant W/C ratio. The parametric study reveals a proportion by volume of clay in the soil beyond which the resistance decreases and thus the stiffness of the material can be problematic for some structural uses. The increase in resistance and the associated stiffness of the soilcrete by increasing the cement dosage is also quantified. The results show that the damage by mechanical load depends mostly on the cement dosage. From the experimental results, mathematical relations are proposed for the dimensioning phase. Various tests of accelerated aging help define thresholds for the indicators of durability (porosity and water permeability). The analysis of the microstructure of the material also shows the importance of the paste-aggregate interface and made it possible to identify some mechanisms of degradation in relation to the exposure conditions. To conclude, this work is finalised by a study of the behavior at high temperature.

Although it has been established that in-situ soil mixing has improved the bearing capacity of soils, additional research is needed to better understand the effect of soil mixing on lateral resistance of pile caps. To do this, in-situ soil mixing was used to strengthen weak clay adjacent to a pile cap of a driven pile foundation. The mass stabilization method or mass mixing was used to treat an 11 ft wide, 4 ft thick, and 10 ft deep zone consisting of an average 475 psf clay that was adjacent to a 9-pile group in 3x3 pile configuration capped with a 9 ft x 9 ft x 2.5 ft, 5000 psi concrete cap. The mass mixing involved 220 cubic ft of in-situ soil and was mixed with an additional 220 cubic ft of jet grout spoils producing a mixing ratio of 1 to 1. All of the mass mixing took place after construction of the pile caps. Laboratory testing of the mass mix slurry showed an unconfined compressive strength of 20,160 psf or 140 psi. Lateral load testing of the pile foundation was then undertaken. The results of this testing were compared with similar testing performed on the same foundation with native soil conditions. The lateral resistance of the native soil was 282 kips at a pile cap displacement of 1.5 inches, and the total lateral resistance of the pile foundation treated with mass mixing was increased by 62% or 170 kips. Of the 170 kips, 90% to 100% can be attributed to the increased passive force on the face of the mass mixed zone and shear on the sides and bottom denoting that the mass mixed zone behaved as a rigid block.

Šiame baigiamajame magistro darbe nagrinėjama gruntbetonio savybių priklausomybė nuo grunto sudėties. Atlikta porų injekcijos ir srautinės injekcijos teorijos apžvalga, išdėstytos šių metodų atlikimo sekos, panaudojimo sritys bei aptartos srautinėmis injekcijomis suformuotų gruntbetoninių kolonų fizikinės savybės. Baigiamojo magistro darbo teorinėje dalyje pateikiama pagrindų stiprinimo injekcijomis apžvalga. Aptariami jų ypatumai, technologijos bei medžiagos, pateikiami kokybės kontrolės metodai, nagrinėjamos dažniausiai kylančios problemos ir jų sprendimo būdai. Eksperimentinėje dalyje nagrinėjama, kokį poveikį priemaišos daro gruntbetonio savybėms. Buvo atliekami laboratoriniai tyrimai, nagrinėjama grunbetonio savybių priklausomybė nuo grunto sudėties. Aprašomi gauti rezultatai, atliekama jų analizė, suformuluojamos išvados. Darbą sudaro 6 dalys: įvadas, literatūros apžvalga, eksperimentiniai tyrimai, išvados, literatūros sąrašas ir priedai. Darbo apimtis – 118 p. teksto be priedų, 35 p. priedų, 78 paveikslėliai, 39 lentelės, 44 bibliografiniai šaltiniai. / This master thesis examines soilerete properties dependence on the composition of the soil. Carried out in pairs at the injection stream and an overview of the theory of the injection set forth in the execution sequence of these methods, fields, and discussed the use of injection-formed soilrets thanks to the physical properties of columns. Master's thesis in theoretical basis for the strengthening of the Review of the injection. Discuss their features, technology and materials, the quality control methods, addresses the most common problems and their solutions. The experimental section deals with the impact of the pollution for soileret properties. Was carried out laboratory tests analyzed in the analysis, formulation of conclusions. The work consists of seven parts: introduction, literature review, experimental studies, conclusions, references, published articles and accessories. Thesis consist of: 118 p. text without appendixes, 35 p.appendixes, 78 pictures, 39 tables, 44 bibliographical entries.

Jet grouting was used to strengthen the soft soil surrounding the piles and the pile cap of two full-scale driven pile foundations. Soilcrete columns, created by jet grouting, were placed underneath the pile cap and surrounding the piles of the first foundation. Two rows of soilcrete columns were placed around the perimeter of one-side of the second. All of the jet grouting took place after construction of the pile caps. Laboratory testing of the soilcrete slurry showed the columns as having a design unconfined compressive strength of 550-650 psi, compared with the native soil strength of only 6-8 psi (850-1150 psf). Lateral loading of the pile foundation was then performed on these foundations. The results of this test were compared with a similar test performed on the same foundations under native soil conditions. The total lateral capacity of the pile foundation treated underneath the pile cap was increased by 500 kips, which equals an increase of 175%. The total lateral capacity of the pile foundation treated adjacent to the pile cap was 150%. Results of testing suggest that each of the jet-grout treated zones displaced as a rigid block. A majority of the increased lateral resistance came from the passive soil resistance acting on the face of the blocks and the adhesive soil resistance acting on the sides and bottom of the block as it displaced through the native soil. The remaining soil resistance, not accounted for by the passive and adhesive soil resistance, can potentially be attributed to increased soil pile interaction, which is predicted from the decrease in pile head rotation during loading following soil treatment.