Soil Improvement and Treatment Techniques

Posted: August 26th, 2021

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Soil Improvement and Treatment Techniques

Summary Report

The state of the art report on soil improvement by Mitchell discusses the uses and applicationof different kinds of methods associated with the treatment of soil. According to the author, the soil is an essential construction material that can be turned into more useful functions in civil engineering. In particular, Mitchell understands that the availability of good construction sites is limited. Therefore, she views the need to utilize poor soils for foundation support as well as earthwork building purposes. With the utilization of the inferior construction materials, the strength of soil has been considerably increased, thereby improving resistance attached to the destructive processes of seismic. The report entails varying concepts associated with soil upgrading and development. For instance,  drainage, densification, cementation, and reinforcement, as well as drying and heating. In this regard, Mitchell has established the purpose of the state of art report as a measure of synthesizing the current poor soil, hence converting it into the most suitable form for the use among civil engineers.

Methods of Soil Improvement and Treatment

For the method and scope of soil treatment and improvement analysis, Mitchell summarizes some choice of methods agreed on by the committee in charge of the state-of-art report. In this case, the report provides a table that formulates all discussed and considered factors that govern the selection of soil improvement methods.

Compaction

The method entails heavy tamping and blasting, which focuses entirely on deep in-situ densification of less cohesive soil particles. Deep compaction is meant to minimize the total differential of incompletely unsettled soil materials, thus reducing the potential of liquefaction under heavy loading. The method is associated with deep in-situ densification that classifies the need for tamping and blasting of less cohesive soils based on different factors. The properties and factors include soil type, degree of saturation and water table location, previous relative density, in-situ stresses, and soil structure. Besides, a vibrio-compaction method involves the insertion of vibration probes into the ground. It is best suited for clean, but less cohesive soil type. The author has demonstrated how deep compaction is less effective with soil type of diameter above 0.0074 mm. The reason is that such kind of soil cannot allow permeability as the bigger particles hinder the drainage of water.

Consolidation

The technique entails all measures associated with strengthening of soil via pre-compression at earlier stages, and successive consolidation before preloading purposes. According to the author, the method is most suitable for soils whose volume decreases mainly, and having strength can be increased when put under continuous static loads. Specifically, the application of the consolidation method involves compression of excessive time to make sure that the vertical drains are well accelerated. Consequently, the best soil type to be upgraded via the consolidation technique is saturated soft clay for the reason that it shows limited secondary compression. Indeed, vertical drains are more useful in soil types like inorganic clay, peats, and silts. Although the earth fills are the greatestuniversally used type of different preload, any system that results in drainage of pore water, as well as firmness of the soil, may be appropriate. The use of water tanks seem applicable in preload of small areas, and a pool lined in ponds has also been useful in the preload of larger cities. However, the utilization of vacuum preloading initiated by pumping from underneath an impermeable membrane placed on the ground surface produces surcharge loadsranging from 60 to 80 kPa

Grouting

It is a kind of injection consisting of clay and hydraulic lime that was first introduced by the French Engineers in 1802. The method is widely recommended for soil stabilization in most construction sites. However, it is costly. Notably, grouting is limited to regions submerged in groundwater. There are three types of grouting, such as permeation, encapsulation, and displacement. Indeed, the application of grouting type methods entails the control of ground movement during the construction of tunnels. Besides, the amount of soil upgrading happens based on the type of soil available, water conditions, as well as the input energy per the unit area. Nonetheless, fine-grained soils cannot undergo the same level of strengthening as coarse materials, simply because the particles are so small. For example, soft layers of clay and peat regularly inhibit high-leveledcompaction of proximatecohesion, thus less material for the lack of flexibility.

Chemical and Thermal Stabilization

Stabilization is among the oldest and widely utilized method that categorizes both chemical and thermal processes. In chemical admixture, it involves the mixing of lime and cement to help restore the properties of soil by ion exchange as well as cementation reactions. In the 1960s, the thermal stabilization was useful in soil cementing of hydraulic structures built alongside upstream slope control of earth dams. Therefore, Mitchell notes that the main objective of using chemical additives is to control the volume stability of the soil, its strength, stress-strain characteristics, permeability, as well as durability. For example, the use of high and low hydration captions like sodium and calcium, respectively, is essential in controlling volume stability via cementation coupled with waterproofing chemicals. On the other hand, thermal stabilization involves the utilization of high temperatures above 100^oC to heatfine-grained soil particles.

Reinforcement

The method is the most widely researched and utilized among all other ways of strengthening and improving soil quality. Compression reinforcement encompasses four types, namely reinforcement earth, soil nailing, root piles, and stone columns. For instance, the stone column is among the most modern techniques of constructing sites by compacting gravel together with sand. The installation of stone columns is done vis-avis vibrio-composer and vibrio-replacement methods. Here, gravel backfills are deposited into incremental holes of 0.4 to 0.8 m and further compacted by a probe that, in turn,dislodges the materials outwardly. Soil nailing is so vital in the strengthening and stabilization of excavated slopes. The use of inextensible inclusion materials like plastics and metals strips, bars, and grids helps increase shear resistance and reduce internal and boundary deformations. According to Mitchell, the application of such materials is based on the rupture strains that are considered less than the maximum tensile stresses exhibited by the soil.

                In summary, as much as many engineers have not yet fully utilized the different methods of soil improvement and treatment, reinforcement has been widely applied in geotechnical constructions. Indeed, the author has mentioned several benefits of using stone and sand columns as a measure of reinforcing buildings with gravel that has considerably helped in regulating the strength of the soil.As noted by Mitchell, when dealing with methods of soil enhancement, experience seems the othertheory. In this case, there is a continuednecessityto develop theoretical rationality of predicting. Thus, evaluating the degree of enhancing the stability of soil systems aboutfundamental properties of the soil and its collaboration with the strengthening materials and processes.

LessonsLearnedfrom Soil Improvement

From the reading of Mitchell, I have learned that there existsignificantfactors, which influence the stability of enforced earth structure based on an association between the soil and its reinforcement mechanism. Indeed, I have come to understand that well designed and built structure holds itself together as a coherent body of interaction. The reason is that such interaction helps control the soil from scatteringsidewaysalongside the reinforcement’s line. In this regard, it has become essential that civil engineers develop a usefulmeasure of confining soil cohesively. The application of the tensile stiffness would automatically attain soil restrain, thus bring about reinforcements. I have come to comprehend that the use of linear tensile reinforcement in exerting themaximum strengthening effect, uniquely when aligned alongside the direction of significant strain extension. Thus, experiencesof dealing with soil improvement make one aware that vibratory methods sufficiently short tons of loose, non-cohesion soils during the fitting of stone columns.

Despite the utilization of saturated and compressible siltsthat may include soft and sensitive clays, these materials would not probably lose strength under the effect of a strong earthquake. With such a premise in mind, it is clear to accept that the use of sufficient adjacent confinement willremain vital in supporting the column. Notably, the author helps us understand that no matter how great the soft ground loses its strength, it would still contain a high-density fluid if the water pressure within the stone column is considered hydrostatic. The reading helps in instructing the significance of applying sufficient confining pressure in soil improvement. The application is attributed tomaintaining the differential pressure inside the high-density fluid,henceexerting extra stress onthe ground surface. In brief, I have learned that when the earth is reinforced with high modulus directtensile materials, the construction becomes economical in terms of costs.