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Journal of Central South University 2016年第10期23卷 2688-2694页

作者： R.Gobinath G.P.Ganapathy I.I.Akinwumi S.Kovendiran S.Hema M.Thangaraj VIT University VelloreIndia Department of Civil Engineering Jay Shriram Group of InstitutionsTiruppurIndia Centre for Disaster Mitigation and Management VIT UniversityVelloreIndia Department of Civil Engineering College of EngineeringCovenant UniversityOtaOgun StateNigeria

The suitability of using precipitated silica(PS) from the burning of rice husk was investigated to improve the geotechnical engineering properties of a black cotton soil. A laboratory experimental program consisting of series of specific gravity, Atterberg limits, compaction, California bearing ratio(CBR), unconfined compression and consolidation tests was conducted on the untreated and PS treated soil samples. The application of PS to the soil significantly changed its properties by reducing its plasticity and making it more workable, improving its soaked strength, and increasing its permeability and the rate at which the soil gets consolidated. An optimal PS content of 50%, which provided the highest soaked strength, is recommended for the improvement of the subgrade characteristics of the BC soil for use as a pavement layer material.

关键词： black cotton soil expansive soil precipitated silica rice husk ash soil stabilization

Adaptability evaluation of pavement structure to replacement treatment subgrade of black cotton soil

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Transportation Safety and Environment 2020年第1期2卷 69-80页

作者： Yingcheng Luan Yuan Ma Weiguang Zhang Yuqing Zhang Tao Ma Jusang Lee School of Transportation Southeast University2#Southeast University RoadJiangning DistrictNanjing 211189China Qilu Transportation Development Group No.1 Lg’ao West RdLixia DistrictJinan 250000China National Engineering Laboratory of Highway Maintenance Technology Changsha University of Science&TechnologyChangsha 410114China Aston Institute of Materials Research Engineering Systems&Management GroupAston UniversityBirminghamB47ETUK Indiana Department of Transportation West LafayetteIN 47906USA

Aiming at the typical engineering problem of black cotton soil(BCS)subgrade under the alternation of dry and wet climate in the region of Nairobi,Kenya,this paper takes the pavement structure as the research object,and the numerical calculation model of BCS subgrade is established based on the consolidation coupling theory of unsaturated *** the modulus and thickness of the subbase as variables,the deformation characteristics and additional stresses of different pavement structures are *** the adaptability of different pavement structures to replacement treatment subgrade of BCS is evaluated by gray incidence decision analysis *** results show that whatever the pavement structure is,neither subgrade modulus nor thickness is sensitive to the pavement surface deformation,and the deformation differences between each pavement structure are more obvious in wet season;the additional stress at control layer bottom and pavement surface decreases with the increase of subbase modulus,whereas the stress may increase at subbase bottom;the additional stress at subbase bottom,control layer bottom and pavement surface all decreases with the increase of subbase thickness for pavement Structure I and *** pavement Structure III,the change of subbase thickness is not sensitive to the additional stress at the control layer bottom and pavement surface,whereas the stress at subbase bottom increases with the increase of subbase *** is concluded that the most adaptable structure is pavement Structure I,which can minimize the comprehensive level of pavement settlement and additional stress.

关键词： black cotton soil pavement structure numerical calculation deformation additional stress

Research on replacement depth of black cotton soil based on cracking behavior of embankment

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Journal of Southeast University(English Edition) 2020年第4期36卷 436-443页

作者： Cheng Yongzhen Huang Xiaoming School of Transportation Southeast UniversityNanjing 210096China Faculty of Architecture and Civil Engineering Huaiyin Institute of TechnologyHuai an 223001China

In order to analyze the influence of replacement depth of black cotton soil(BCS)foundation on the initial cracking depth of a highway embankment,the laboratory tests were performed to construct the constitutive relationship between state variables and stress variables of BCS,and the coupled consolidation theory for unsaturated soils was employed to simulate the change in the major principal stress of the subgrade soils caused by water loss shrinkage of BCS with the help of Abaqus 6.11 *** simulation results indicate that the water losing shrinkage of BCS causes tensile stress within the subgrade,which leads to embankment *** crack depth decreases with the increase in the BCS replacement depth and the embankment height,and increases with the increase in the burial depth of *** the distribution area of deep BCS,the key values of foundation replacement depth for controlling the crack depth of the embankment with the height of 1 to 4 m are 1.2 and 1.5 *** the low filling section,when the buried depth of BCS is 2,3 and 4 m,the key values of the foundation replacement depth to control the crack depth of the embankment are 0.8 and 1.2 *** order to control the embankment cracking induced by the water losing shrinkage of BCS,a reasonable replacement depth of the foundation should be selected while slope protection is carried out well.

关键词： black cotton soil coupled consolidation theory for unsaturated soils major principal stress embankment crack replacement depth

Clay mineral expansion of black cotton soil based on interlayer cation hydration

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Journal of Southeast University(English Edition) 2021年第3期37卷 299-305页

作者： Cheng Yongzhen Huang Xiaoming School of Transportation Southeast University Nanjing 210096 China Faculty of Architecture and Civil Engineering Huaiyin Institute of Technology Huai'an 223001 China

To analyze the water swelling characteristics of black cotton soil(BCS),X-ray fluorescence and X-ray diffraction characterizations were performed to investigate the chemical compositions and types of clay minerals in BCS.A montmorillonite crystal lattice was established to simulate the hydration of interlayer cations by applying the SPC/E potential energy model,universal force field,algorithm of charge balance,and periodic *** indicated that the main clay mineral found in the BCS was montmorillonite(32.6%)with small amounts of interstratified illite-montmorillonite(10.9%),illite(2.3%),and kaolinite(1.5%).The high expansive potential of BCS comes from the strong adsorption property of montmorillonite with a high content of magnesium and sodium ions to water *** exchangeable cations of Na^(+)in BCS were only 3.73%,but they enhanced the adsorption capacity of clay to water molecules and accelerated the hydration of Mg^(2+)(47.1%)and Ca^(2+)(4.78%).The free swell index can be used as a classification index of the swelling potential of BCS.

关键词： black cotton soil swelling characteristics clay minerals molecular simulation interlayer cation hydration

Load Settlement Characteristics of Model Footings Resting on Surface Treated Coir Fiber Reinforced BC soil Overlying Loose Stratum

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Journal of Geological Resource and Engineering 2017年第2期5卷 87-92页

作者： Jairaj M. T. Prathap Kumar Ganapathi Gayithri Department of Civil Engineering NMIT Bangaluru 560064 and Resarch Scholar GCE Ramanagara 571511 India Department of Civil Engineering RNS Institute of Technology Bengaluru 560098 lndia Department of Civil Engineering NMIT Bangaluru 560064 India

In nature there are situations where in foundation had to be placed over loose soil deposits. In such cases, deep foundations are recommended which increases cost of the structure. black cotton soils, because of its high swelling and shrinkage characteristics, have been a challenge to geotechnical engineers, increasing the strength of Clayey soil which is formed introducing randomly distributed fibers results in comparatively more homogeneous soil mixture and is one of the popular methods of soil stabilization. In the present study, model footing resting on BC soil reinforced with optimum percentage of treated and untreated coir fiber underlain by loose soil deposit was conducted to study its influence on bearing capacity and settlement. Loose soil deposit has been simulated by compacting sawdust in prefabricated steel tank. BC soil reinforced with optimum percentage of treated and untreated coir fibers has been compacted over loose sawdust and load settlement characteristics were determined at various D/B ratio of 1,2, 3 and for different sized model footings. The results indicated that settlement of model footings is significantly small at lower D/B = 1 and 2 ratios. Bearing capacity of BC soil is also found to be significantly affected by fiber reinforcement.

关键词： black cotton soil model footing treated coir fiber bearing capacity factor RDF.