Soil stabilization

About: Soil stabilization is a research topic. Over the lifetime, 3161 publications have been published within this topic receiving 48437 citations.

Sydney Soil Model. II: Experimental Validation

Abstract: This paper presents simulations of the mechanical behavior of reconstituted and natural soils using a new model presented in a companion paper and referred to as the "Sydney soil model." It is demonstrated that the performance of the proposed model is essentially the same as that of modified Cam clay model when describing the behavior of clays in laboratory reconstituted states. The model has also been employed to simulate the drained and undrained behavior of structured clays and sands, including calcareous clay and sand. Five sets of conventional triaxial tests and one set of true triaxial tests have been considered. It is demonstrated that the new model provides satisfactory qualitative and quantitative modeling of many important features of the behavior of structured soils, particularly in capturing various patterns of the stress and strain behavior associated with soil type and structure. A general discussion of the model parameters is also included. It is concluded that the Sydney soil model is suitable for representing the behavior of many soils if their ultimate state during shearing can be defined by an intrinsic and constant stress ratio Mand a unique relationship between mean effective stress and voids ratio, i.e., a unique p 0 � e curve. DOI: 10.1061/(ASCE)GM.1943-5622.0000079. © 2011 American Society of Civil Engineers. CE Database subject headings: Clays; Sand, soil type; Calcareous soils; Fabrics; Constitutive relations; Plasticity. Author keywords: Clays; Sands; Calcareous soils; Fabric; Structure of soil; Constitutive relations; Plasticity.

Improving fine-grained gypsiferous soil by increased compaction

Abstract: Presented in this paper is a study of the effect of compactive effort (CE) and long-term soaking on the strength characteristics of a clayey gypsiferous subgrade soil. The tested soil is A-6 (6) soil according to American Association of State Highway and Transportation Officials (AASHTO) soil classification system. To study the effect of CE and long term soaking on the properties of the tested soil, various California bearing ratio soil samples were prepared and compacted at optimum moisture content of the modified AASHTO compaction, but using four different chosen CEs of 12, 25, 56 and 70 blows/layer and then soaked for 0, 4, 7, 15, 30 and 120 days. The California bearing ratio (CBR) tests indicate that the CBR increases significantly in a nonlinear manner with increasing CE for all soaking periods, indicating improvement in soil strength with increased compaction. The rate of increase dies out with increasing CE. The CBR tests reveal also that there is a serious drop in the CBR due to soaking for all CEs.

Hydraulic fills to support structural loads

Abstract: Data are compiled based upon a review of the literature, concerning the relative density, penetration resistance, compressibility and rate of consolidation Only hydraulic fills placed by sluicing through pipes are considered, and emphasis is upon performance under ordinary dead and live loads Fills are classified according to the nature of the borrow materials: (1) fairly clean sand, resulting in a reasonably uniform fill of moderate density; (2) silty or clayey sand, for inhomogeneous fill of large void ratio; (3) stiff cohesive soil, resulting in a skeleton of clay balls with a matrix of sand and clay; and (4) soft cohesive soil, resulting in a laminated normally consolidated clay The characteristics of each type of fill are illustrated by a case study The placement and engineering properties of the most desirable type of fill—that derived from a fairly clean sand—are considered in detail

Stabilization and Improvement of Organic Soils

Abstract: Peats and organic soils in general pose significant problems to geotechnical engineers due to their low strength, high compressibility and elevated creep. The research performed addressed one soil improving technique, deep soil mixing, that has been widely used for treating soft clays, but that especially in the US has found limited use in presence of organic soils. The work performed made use primarily of one soil sampled on Lindberg Road (LR) in West Lafayette, Indiana characterized by LOI= 45-52%, LL= 327%, PL= 162%, LLoven dried/LLnon-dried = 0.31, Gs = 2.05-2.12, fiber content ~2.29%, clay fraction = 40.6%. In addition, a limited number of tests were performed making use of soils with LOI of 10-20%, manufactured in the lab from LR soil and an illitic clay. A procedure was developed for preparing samples of reconstituted LR soil both untreated and mixed with a binder and which included a “curing” stage under a surcharge to simulate treatment at depth. Specimens obtained from these samples were used for the engineering tests which included constant rate of strain (CRS) consolidation tests, end-of-primary incremental loading (EOP-IL) consolidation tests with one long term creep stage, and unconfined compression tests. A battery of characterization tests and an in depth review of the literature complemented this work. Unconfined compression tests provided a preliminary evaluation of the effects of treatment on the strength of the soil; highlighted the effects of curing under a surcharge; and allowed to identify in Portland cement (PC) the most promising binder, which was subsequently used for all other engineering tests, at dosages ranging from 8% (~25 kg/m3) to 100% (~320 kg/m3)by dry mass of the soil. The results of the consolidation tests highlighted how the accurate characterization of the primary consolidation behavior of soils characterized by high tendency to creep must rely on either CRS or EOP-IL loading tests and demonstrated the effects of treatment with cement on the stiffness, the hydraulic conductivity, the rate of consolidation and the rate of creep of the soil. Specifically, the tests showed how the addition of cement is associated with the development of a preconsolidation pressure and the shift of the compression curve towards higher effective stresses. Once this yield stress is exceeded the compressibility in the virgin compression range is found not to vary significantly with cement content. Also associated with the addition of cement is an increase in the hydraulic conductivity, an increase in the coefficient of consolidation, and a reduction in the creep coefficient at any given stress level. Moreover, the Cα/Cc ratio decreases markedly with cement addition indicating a decreased susceptibility of the soil to creep. All these effects are more marked with increasing cement content and the treatment appear especially effective once the PC% exceeds 50% (~160 kg/m3).