In view of the challenges posed by the nature of expansive soil to structural stability which makes it necessary in some cases to improve the soils before structures can be placed on them, there is a need to investiga...In view of the challenges posed by the nature of expansive soil to structural stability which makes it necessary in some cases to improve the soils before structures can be placed on them, there is a need to investigate modern trends in ground improvement techniques in order to determine their reliability. This study is thus aimed at using the reliability based approach to analyze the use of polyvinyl alcohol (PVA) in combination with 1,2,3,4 Butane-tetracarboxylic acid (BTCA) for ground improvement. This study is necessary given the challenges posed by the nature of expansive soil to structural stability which makes it necessary in some cases to improve the soils before structures can be placed on them. Simplex lattice design was employed to build the design of experiment before experimental investigations were carried out on the PVA-BTCA treated soft soils. Reliability indices were computed on the basis of the 28<sup>th</sup> day unconfined compressive strength (UCS) of the treated soil. Reliability index models were developed using the Scheffe’s technique and optimized using excel solver. From analysis of results, reliability model developed proved adequate at 5% level of significance. PVA-BTCA combination provided a potential reliability or probability of success of 99.936% at components combination of: 98.4256% for soil, 1.2352% for PVA, 0.3392% for BTCA and 15.9934% for water. It was therefore recommended that financial implications of using PVA-BTCA for stabilization be compared to those of conventional methods, in order to compare their performance-cost ratio.展开更多
Hydrothermal reactions of three aromatic polycarboxylic acids and the transitional metal cations in the presence of phen and 1,4-bib afford three new coordination polymers： [Cd2（bpp）1.5（Hbpp）（phen）2]n （1）, [...Hydrothermal reactions of three aromatic polycarboxylic acids and the transitional metal cations in the presence of phen and 1,4-bib afford three new coordination polymers： [Cd2（bpp）1.5（Hbpp）（phen）2]n （1）, [Mn3（Htptc）2（phen）2（H2O）2]n （2）, and {[Cu（btc）0.5（1,4- bib）]·2H2O}n（3） （H2bpp = 2,6-bis（4＇-carboxyphenyl）-4-phenylpyridine, H4tptc = terphenyl-2,5,2＇,5＇-tetracar- boxylic acid, H4btc =biphenyl-2,2＇,4,4＇-tetracarboxylic acid, phen =1,10-phenanthroline, and 1,4-bib = 1,4-bis（1H-imidazol-1-yl）benzene）. Their structures have been determined by single- crystal X-ray diffraction analyses, elemental analyses, IR spectra, and powder X-ray diffraction （PXRD） analyses. In compound 1, the CdII cations are linked by bpp2- to form one ladder structure, based on which a 3D network is constructed with the help of non-covalent interactions. The topology of 2 is a 3D （3,4,5）-connected framework with the Point Schl？fli symbol of （42.6）2（43.62.8）（45.64.8）2. Compound 3 shows an unprecedented 3D （4,4）-connected framework with the Point Schl？fli symbol of （64.82）2（65.8）. Moreover, the luminescent property of 1 has been investigated.展开更多
文摘In view of the challenges posed by the nature of expansive soil to structural stability which makes it necessary in some cases to improve the soils before structures can be placed on them, there is a need to investigate modern trends in ground improvement techniques in order to determine their reliability. This study is thus aimed at using the reliability based approach to analyze the use of polyvinyl alcohol (PVA) in combination with 1,2,3,4 Butane-tetracarboxylic acid (BTCA) for ground improvement. This study is necessary given the challenges posed by the nature of expansive soil to structural stability which makes it necessary in some cases to improve the soils before structures can be placed on them. Simplex lattice design was employed to build the design of experiment before experimental investigations were carried out on the PVA-BTCA treated soft soils. Reliability indices were computed on the basis of the 28<sup>th</sup> day unconfined compressive strength (UCS) of the treated soil. Reliability index models were developed using the Scheffe’s technique and optimized using excel solver. From analysis of results, reliability model developed proved adequate at 5% level of significance. PVA-BTCA combination provided a potential reliability or probability of success of 99.936% at components combination of: 98.4256% for soil, 1.2352% for PVA, 0.3392% for BTCA and 15.9934% for water. It was therefore recommended that financial implications of using PVA-BTCA for stabilization be compared to those of conventional methods, in order to compare their performance-cost ratio.
基金supported by the National Natural Science Foundation of China(20873150)the Natural Science Foundation of Shandong Province(ZR2010BL012,ZR2010BQ023)
文摘Hydrothermal reactions of three aromatic polycarboxylic acids and the transitional metal cations in the presence of phen and 1,4-bib afford three new coordination polymers： [Cd2（bpp）1.5（Hbpp）（phen）2]n （1）, [Mn3（Htptc）2（phen）2（H2O）2]n （2）, and {[Cu（btc）0.5（1,4- bib）]·2H2O}n（3） （H2bpp = 2,6-bis（4＇-carboxyphenyl）-4-phenylpyridine, H4tptc = terphenyl-2,5,2＇,5＇-tetracar- boxylic acid, H4btc =biphenyl-2,2＇,4,4＇-tetracarboxylic acid, phen =1,10-phenanthroline, and 1,4-bib = 1,4-bis（1H-imidazol-1-yl）benzene）. Their structures have been determined by single- crystal X-ray diffraction analyses, elemental analyses, IR spectra, and powder X-ray diffraction （PXRD） analyses. In compound 1, the CdII cations are linked by bpp2- to form one ladder structure, based on which a 3D network is constructed with the help of non-covalent interactions. The topology of 2 is a 3D （3,4,5）-connected framework with the Point Schl？fli symbol of （42.6）2（43.62.8）（45.64.8）2. Compound 3 shows an unprecedented 3D （4,4）-connected framework with the Point Schl？fli symbol of （64.82）2（65.8）. Moreover, the luminescent property of 1 has been investigated.
