Applications soil consolidation

Poly(acrylic acid) and its salts have been known to have useful binding properties for some thirty years they have been used for soil consolidation (Lambe Michaels, 1954 Hopkins, 1955 Wilson Crisp, 1977) and as a flocculant (Woodberry, 1961). The most interesting of these applications is the in situ polymerization of calcium acrylate added to soil (de Mello, Hauser Lambe, 1953). But here we are concerned with cements formed from these polyacids. 

Applications - brake linings, composites, foundry, mortar cements, refractory materials, sand and soil consolidation, wood modification ... 

Sampling into airtight coring devices works best for relatively cohesive yet uncemented soils. This technique is not applicable for soils, which contain gravel or rocks or are too hard (cemented) for the device barrel to be pushed into the soil. Soil, which is too sandy or is excessively wet will allow easy penetration with the barrel, however if it is not sufficiently consolidated, it may fall out of the barrel before it is capped. 

Solidification of minerals in carbonate rocks or in sea shells, or that of silica and alumina in lateritic or desert soils, is a very slow process. It takes years and centuries and even geological time to consolidate some minerals. Unfortunately, little is known on the exact chemical reactions and the resulting hardening process. As a result, the chemical hardening in nature cannot be translated into technological applications where accelerated hardening and solidification are desired. 

In spite of the above issues, consistent trends of increasing surface area with increasing intensity of natural weathering are observed (Brantley et al., 1999). An example of this increase is shown in Figure 12(a) in which BET surfaces of primary minerals increase with increasing age of soils in the Merced chronosequence (White et al., 1996). The extent of this increase depends on the specific mineral phase. The more readily weathered aluminosilicates exhibit greater surface area increases than quartz. Application of BET measurements to characterize fractures and porosity in consolidated rocks has remained generally untested these surface area estimates have been... 

Applying stress to any material results in a corresponding strain. For the common building materials such as steel and concrete the strain occurs virtually instantaneously with stress application. In contrast, fine-grained soils generally exhibit a measurable time lag between stress application and the resulting strain. This phenomenon is called consolidation. 

Soil samples are generally taken vertically consolidation samples are taken from a horizontal slice. The coefficient of consolidation from such a test is based on vertical flow, which is applicable for much field work. (For projects using, for example, vertical sand drains, much of the flow is in the... 

Calcification by bacteria. Lime-water application seems not to guarantee sufficient consolidation. Precipitation of calcite by microorganisms is known to occur in freshwater and marine environments, as well as in soil, and this led to trials of bioremediation on heritage surfaces. Very recently, approaches using calcification due to bacterial activity have even been carried out particularly on stone and architectural surfaces (see page 236). Remediation by several bacteria was shown to result in the formation of newly developed calcite precipitations. For this, chemoorganotrophic bacteria, as well as nutrients, were supplied to the surfaces. Up to now the role of bacteria is not completely understood, however, studies on marine bacteria revealed three main mechanisms (i) calcium-binding membrane proteins, (ii) ionophores, and (iii) extracellular materials on cell surface. 

Abstract This paper introduces the current state of research on the coupled Thermal-Hydraulic-Mechanical-Chemical (THMC) processes in geo-materials and applications for geotechnical and geo-environmental engineering in China. The paper puts equal emphasis on both the achievements of experimental results for fundamental studies, and the applications in rock mechanics and foundation engineering, tunnel engineering, geothermal mining, unsaturated soil and dynamic consolidation. At the end, it presents a model for chemical mining. 

Important applications for coupled finite element strategies can be found in the theory of consolidation of partially saturated soils. Some test cases were performed, (see Kohlmeier et al. (2002)) using the Richards formulation. 

One-dimensional consolidation or confined compression, has a wide range of applicability in soil mechanics for testing insensitive and uncemented sediments. This arises because the sedimentation and subsequent consolidation of level ocean sediments is essentially... 

The outcomes in terms of the soil mechanics and their understanding of consolidation and its application have been mixed. While many students are able to produce a report showing a good understanding, there are too many students who report that the assignment is just too hard. How to identify and support these students is an ongoing challenge. 

Consolidation is another topic which students found hard to cope with. After explaining the concept and its applications in detail systematically and slowly, I gave them some real cases to think about. The Nicoll Highway incident (Ministry of Manpower, 2005) with the collapse of the retaining structure after 33 m of soil excavation in soft marine clay that occurred in Singapore in April 2004 was used an illustrative example. Towards the end of the consolidation topic coverage, students were asked to voluntarily submit their calculations on whether the 50-m thick soft marine clay has completed its consolidation settlement under a reclaimed sand fill placed about 50 years ago. 

For footing in clay and other fine-grained soils with relatively low permeability compared to the rate of static load application, the total settlement (s is the sum of the immediate or elastic settlement evaluated based on Equation 8.36 and the consolidation settlements as discussed in Section 8.10.3.1. 

The primary consolidation settlement (sj occurs due to the slow expulsion of the pore water and hence the dissipation of the excess pore water pressure generated by the application of the static service loads at the rates normally expected of permanent loads. As the excess pore water pressure dissipates, the net effective vertical stress on the soil increases as the primary consolidation continues to occur. 

Jute geo-textile is another product with a potentially large-scale application. It can have several uses soil erosion control, vegetation consolidation, agromulching materials, and road pavement construction. 

In some cases, the application of surcharge might be impossible for stability reasons or because of a shortage of suitable surcharge material. In such cases the use of vacuum consolidation techniques to improve the shear strength of the cohesive soil might be a suitable alternative. Reference is made to the case study on the use of alternative material in Bremenhaven, see box below. 

Application of the model to clay-solution aggregates showed that the radiofrequency dispersions of these systems at 10-50 MHz are fairly well described by the model. These dispersions were found to depend on the clay type (kaolinite, illite, montmorillonite), degree of consolidation, and soil fabric these properties are reflected in the values of the geometrical parameters and of the dielectric constant of the solid which fit the dispersion curves best. 

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