I need to rewrite a report for Liquefaction in Soils the same date but different intro title abstract materials

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I need to rewrite a report for Liquefaction in Soils the same date but different intro title abstract materials

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Liquefaction in soils and its Remedial Measure Abstract Liquefaction occurs when vibrations i.e. earthquake within a mass of soil cause increased in pour water pressure and decrease in effective stress. As a result, the soil behaves like a liquid, has an inability to support weight and can flow down very gentle slopes. It is very dangerous for the existing structure. Liquefaction most of the time occurs in loose saturated sandy soil. When earthquake occurred in saturated soil the soil particles are apart from each other because voids are filled with water and pour water pressure start increasing at one stage effective stress become equal to zero. Mechanism of Liquefaction Soil is essentially a mixture of many soil particles remain in contact with many neighbor particles. Contact forces produced by the weight of the particles. Liquefaction is the result of applying quick loading and drop, on saturated sand and soil particles loosely packed trying to move into a denser configuration. However, there is not enough water in the pores of the soil to be squeezed when earthquakes occurred. There is an increased water pressure to reduce the contact forces between the soil particles detached causing softening and weakening of the soil deposit. The soil particles lose contact with one another due to pore water pressure. In such cases, the soil will have very little strength, and will behave more like a liquid than a solid. τf= (σ − u) tanϕ The τf shear strength is dependent on the total stress & pore water pressure. Earthquake causes the pore water pressure to increase and consequently reduce the shear strength. When pore pressure is equal to total stress, soils full of fluid. Causes of Liquefaction: Liquefaction has been observed in earthquake for many years. Liquefaction occurs when the structure of loose, saturated sand breaks down due to some rapidly applied loading. During an earthquake there is not enough time for water in the pores to squeeze out. If the shear resistance of soil becomes less than the static, driving shear forces so soil can undergo large deformation and is said to liquefy. Susceptibility of soils to Liquefaction in Earthquakes The liquefaction is most commonly observed in shallow, loose soil saturated, non-cohesive soils subjected to strong ground motions for earthquakes. In practice, the potential of liquefaction of the soil deposit during an earthquake is often assessed by means of in situ penetration testing and empirical procedures. Well graded soils, due to its stable configuration of inter locking, are less prone to liquefaction. Koester (1994) stated that sandy soils with appreciable fines content can be collapsible, perhaps because of the greater compressibility of fines between grains of sand. Permeability also plays a significant role in liquefaction. When the pore water movement in the soil is retarded by low permeability, pore-water pressures are likely to generate during cyclic loading. Soils with high content of non-plastic fines are more likely to be liquefied because fines inhibit drainage of excess pore-pressure. Gravelly soils are fewer tendencies to liquefaction due to a relatively high permeability unless pore water drainage is impeded by less pervious, adjoining deposits. Case Study Niigata Earthquake 1964 Introduction: The Niigata earthquake of June 16, 1964 had a magnitude of 7.5 and caused severe damage to many structures in Niigata. The destruction was observed to be largely limited to buildings that were founded on top of loose, saturated soil deposits. Even though about 2000 houses were totally destroyed, only 28 lives were lost. The earthquake caused liquefaction over large parts of the city. Soil profile: Topographically the city of Niigata may be divided into Aeolian sand dunes running parallel with the coastline. The profile shows that soil is primarily sandy down to depths of 20 to 30 meters. Very loose sand for which value of N is less than 5 at some places extends to very great depths. Within in the sandy strata there are isolated thin lenses of sandy silt, silty sand, or these with the organic matter having high compressibility. Ground water table is quite shallow partly due to ground subsidence in the area. Liquefaction: The Niigata earthquake 1964 brought liquefaction phenomena and their devastating effects to the attention of engineers and seismologists. A remarkable ground failure occurred near the Shinano river bank where the Kawagishi-cho apartment buildings suffered bearing capacity failures and tilted severely (left). Despite the extreme tilting, the buildings themselves suffered remarkably little structural damage. Damage to building foundations: To predict the nature of damage some of the buildings were excavated for direct inspection. Damage to superstructure is examined on basis of type of foundation. ➢ Shallow foundations Buildings on mat foundation suffered the least damage, buildings on strip footings performed slightly performed better than the buildings on isolated footings. Buildings on shallow foundations with N-values less than 15 suffered considerable damage in their superstructure whereas few buildings founded on N-values greater than 15 were damaged. ➢ Pile foundations Degree of damage seemed to depend upon the depth of pile penetration and on soil at the pile point. Short piles whose tips were located on soil with small N-value suffered severe settlement and tilting. Probably because of the soil at pile tip completely lost its strength due to liquefaction of soil during earthquake. Curve ABC gives critical N-values for liquefaction. Damaged buildings are located below DBE and undamaged are located above the curve. In zone ABD the soil above the pile tip was liquefied and soil at pile tip was unaffected. REMEDIAL MEASURE Compaction grouting Compaction grouting and grout is injection of low liquidity, still thick Homogeneous mass that did enter the soil pores. Grout as a massive expansion, the soil around are displacement and dense Shown in Figure pressure Grouting concept plan. According to Rubright and Welsh (1993), the development of compaction Grouting technique in the early 50 in the United States. It has been used successfully to correct structured settlement to prevent tunneling in soft soil foundation settlement in urban areas, protection of the local area sinkholes structure and density of the liquefiable soils. Fig. Conceptual Drawing of Soil Densification by Compaction Grouting. Permeation grouting Permeating Grouting is a low viscosity liquid for injecting particles small changes in the pore spaces of the soil on the physical structure of the soil. The main objectives or cementing soil particles or enhanced permeation Grouting on the ground is by entering the soil pores reduces water flow. Concept mapping is permeating Grouting as shown in Figure 9. Permeating Grouting dates back to the 19th century (Glossop, 1961). Penetration Grouting technique has been successfully used to control of groundwater flow, stability of soft ground Foundation excavation, consolidation of existing Foundation and to avoid regulation and induced earthquake Liquefaction. Fig. Conceptual Diagram of Soil Solidification by Permeation Grouting. Jet grouting Jet grouting and high pressure fluid are used to replace with the weak soils. The General installation process begins with the storm a small hole, usually 90the final depth of 150 mm diameter, as shown in the figure. Deep in the mix in the soil through a small nozzle as a rotating drill pipe has been deleted. Cuttings a steady stream of from the ground up to the pressure of the Jet to the point you need to prevent buildings foundation spray pressure causes deformation of the Earth's surface. According to Bell (1993), a lot of the early generation Jet Grouting took place in Japan and Europe in the late 70 ' s technology has been the world's. The technique has been used worldwide to underpin existing foundations, support excavations, control ground water flow, and strengthen liquefiable soils. Fig. Procedure for Jet Grouting (Ichihashi et al.1992). In situ soil mixing In situ soil mixing is the mechanical mixing of soil and the stabilizer with a rotating propel lerand mixing bar. Plot of soil by mixing process is in place shown in Figure. How to exercise to penetrate the ground, stabilizer is pumped through the rotating shaft. Uniform mixing of the shaft mix to inject stabilizer soil. After reaching the designed depth second mixing occurs both exercises will be removed. Broomhead and Jasperse (1992), plenty of space for mixing soil development occurred in Japan in the past 20 years. It has been successfully used to control the flow of underground water support to stabilize embankments and slopes, excavations to increase stability and the liquefaction-induced ground movements. Fig. Conceptual Drawing of the In Situ Soil Mixing Technique. Low vibration drain pile Ono et al. (1991) described a low vibration system for constructing gravel drain pile susing a large casing auger. The construction sequence of this system is illustrated in Fig The casing is screwed downward into the ground, while simultaneously pouring water into the casing to sediment flow into the casing. Gravel is discharged into the casing upon reaching the final depth. As the casing is unscrewed, gravel is pushed out the end of the casing and compacted by a rod. One study showed that standard penetration resistances measured at the midpoint between piles after installation were about 5 blow counts higher than before installation. The most important factors affecting densification are the shape of the impact surface of compaction rod, the number of compactive strokes, and the stroke length. When drains are installed without the compaction rod, little densification occurs. The low vibration drain pile technique has been used in Japan for liquefaction remediation near existing structures. Fig. A Low Vibration Procedure for Installing Gravel Drain Piles REFFRENCE • Andrews, D.C.A. and Martin G.R. (2000) “Criteria forLiquefaction of Silty Soils”, Proc. 12th WCEE, Auckland, NewZealand. • Chen and Juang (2000). Liquefaction likelihood classification • Seed H.B., Tokimatsu, K., , L.F., and Chung, R. (1985),“Influence of SPT Procedures in Soil Liquefaction ResistanceEvaluations” J. Geotechnical Engg. • Olson, S. M. and Stark, T. D. 2002. Liquefied strength ratio from liquefaction flow failurecase histories. Canadian Geotechnical Journal • Kramer, L., Steven (1996). "Geotechnical earthquake engineering." Prentice Hall Series. • Ichihashi, Y., Shibazaki, M., Hiroaki, K., Iji, M., and Mori, A. (1992). “Jet Grouting in AirportConstruction,” Proceedings, Grouting, Soil Improvement and Geosynthetics. GeotechnicalSpecial Publication No. 30, held in New Orleans, • One, Y., Ito, K., Nakajima, Y., and Oishi, H. (1991). “Efficient Installation of Gravel Drains,”Proceeding. Second International Conference on Recent Advances in Geotechnical EarthquakeEngineering and Soil Dynamics, held in St, Louis, Missouri, on 11-15 March, S. Parkash, Ed.,University of Missouri-Rolls, U PICIUN (IU. 1. Individual Proposal is required to include the following items. (linimum # of page: 5. Maximum of page; 10) (Due: Thur, Sept 6, 2018) Title --- Introduction Problems ...Methodologies and Scientific Discussion Expected Results & Outcomes Cited References 2. Preliminary (Progress) Report: Including the following items nber 18, 2018) Title Abstract Introduction Materials and Methods Observation - Analysis of the Results & Discussion Conclusion --References - Appendix 3. Final Report: (Due Ther 29, 2018 for Dec Graduates, Thur. December 6, 2018 for Regular Students) Format: same as the Progress Report
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