The property of the contact surface between geosynthetics and soil directly affects the whole structure＇s stability. The interface property is one of the most important indices for the reinforced structure. Systemati...The property of the contact surface between geosynthetics and soil directly affects the whole structure＇s stability. The interface property is one of the most important indices for the reinforced structure. Systematic direct-shear tests with large direct-shear apparatus are carded out for geobelt reinforced clay under different normal stresses and water content. A reinforcement-sand-clay layer system improving the interface behavior greatly is designed. The stress-strain relationship is investigated on the basis of the experimental results. The results show that with the increase of the normal stress, the shear strength between the clay and the reinforcement increases nonlinearly, and with the increase of the water content, the friction coefficient between the clay and the reinforcement decreases dramatically and the cohesion between the clay and the polypropylene geobelt increases initially, then decreases. There is an optimal value for the water content between the clay and the polypropylene geobelt, which is 2% lower than the optimal water content of clay compaction. This reinforcement-sand-clay layer system improves the shear strength of the interface remarkably. Therefore, the clay-sand-reinforcement layer system is a rather good design for practical use in reinforcement engineering.展开更多
The deep, loose bottom aquifer of the eastern air shaft in the Xinglongzhuang Coal Mine was used to develop an experimental model of shaft grouting through Model deep soil. Lab experiments using chem- ical grouting we...The deep, loose bottom aquifer of the eastern air shaft in the Xinglongzhuang Coal Mine was used to develop an experimental model of shaft grouting through Model deep soil. Lab experiments using chem- ical grouting were done to study the grout. The grouted soil shapes and osmotic pressure were measured during the experiments. The tested characteristics of the grouted soil show that the diffusion mode of grout in saturated sandy soil is a combination of split compaction and osmosis. More specifically, the shape of the grouted soil is determined by split compaction while the size of the grouted soil shape is determined by osmosis. Sensor test results indicate that the main reason for the non-uniform grout diffusion is the anisotropic osmotic pressure field surrounding the grouting holes.展开更多
Deep coal mines in northern Anhui province, China, provide opportunities for tracing the distribution and fractionation of rare earth elements CREEs） in deep seated environments. Major ions, as well as REE concentrat...Deep coal mines in northern Anhui province, China, provide opportunities for tracing the distribution and fractionation of rare earth elements CREEs） in deep seated environments. Major ions, as well as REE concentrations were measured in groundwater from a sandstone aquifer located between -400 and -280 m. Our results indicate that this groundwater consists of CI.HCOH-Na or CI.CO3-Na water types with warm temperature （30.1-31.4~C）, circumneutral pH （7.27-8.61） and high levels of total dissolved solids （TDS ~ 1306--2165 mg/L）. Concentrations of REEs in groundwater are high as expressed by their Nd con- centrations （0.0086-0.018μg/L）. Except for weak heavy REEs （HREE） enrichment relative to light REEs （LREE）, the similarity of REE distribution patterns between groundwater and aquifer rock indicate that enrichment of REEs is considered to be controlled by aquifer rock, as well as by their minerals, whereas the fractionation of REEs is controlled by HREE enriched minerals and, to a lesser extent, by inorganic REE complexes. Ce anomalies normalized to Post Archean Average Shale （PAAS） and aquifer rock are weak, which probably reflect the contribution of reduced conditions in combination with pH, rather than a sig- nature of aouifer rock.展开更多
This study proposes a model to determine the content of cement in mortars using the background of X-ray diffraction （XRD） spectra taking advantage of the fact that fluorescence radiation for the Cu anticathode is di...This study proposes a model to determine the content of cement in mortars using the background of X-ray diffraction （XRD） spectra taking advantage of the fact that fluorescence radiation for the Cu anticathode is different in cement paste and aggregates, and also that cement paste and aggregates have different crystallinity degrees. The method has been tested for limestone mortars with five different types of cement： I52,5N/SR, CEMII/A-L32,5N, IIIA42,5N/SR, IVA（V）32,5N/SR y CAC.展开更多
An experience formula of expansive strain and stone taken from a foundation pit of Hongshanyao Project (HSYP) in Nanjing was described. It is clear that the curve of expansive strain-water content is a logarithm. In t...An experience formula of expansive strain and stone taken from a foundation pit of Hongshanyao Project (HSYP) in Nanjing was described. It is clear that the curve of expansive strain-water content is a logarithm. In the meantime, the relation of expansive strain with time was studied and the importance of expansive stabilization time was illu-minated. The experiment results indicated that the water content has a tremendous effect on peak expansive and steady expansive deformation of swelling red sandstone.展开更多
In this paper, a study of sandy soil compaction with different granulometry and moisture content has been performed, and soil mechanical property variations in moisture and granulometry have been investigated. Investi...In this paper, a study of sandy soil compaction with different granulometry and moisture content has been performed, and soil mechanical property variations in moisture and granulometry have been investigated. Investigations were performed to compare hydrostatic compression test （HCT） responses and evaluate the compression index, Cc, which is an indicator of the soil＇s susceptibility to compaction-induced damage. The experiments have been performed on 24 soil samples typologies. Each sample has been obtained by combining three types of soil granulometry （types A, B and C） with a relative content varying from 0% to 100% in 20% increments. Soil type A had a granulometry ranging between 0.5 mm and 1 mm, type B between 0.25 mm and 0.5 mm, and type C less than 0.25 mm. These samples were representative of a sandy soil, chemically inactive and had various granulometries and initial moisture contents. A cell for HCT has been set up to allow the initial volume measurement of the test pieces and the subsequent changes during HCT with an estimated error less than 0.1 cm3. All samples were pre-compacted and prepared in agreement with the actual standards. The experimental data are reported in diagrams, the data allowed comparison of the mechanical behaviors between the considered unsaturated soils and underlined how soil moisture and granulometry affect soil response during HCT. Furthermore, because of the methodology used, the equipment was very economical.展开更多
The seismic velocities are strongly influenced by porosity and degree of water saturation, as well as other petrophysical properties, such as density and elastic properties of the rocks. In this paper, the saturation ...The seismic velocities are strongly influenced by porosity and degree of water saturation, as well as other petrophysical properties, such as density and elastic properties of the rocks. In this paper, the saturation of water percentage for sandstones （SW%） has been calculated by mathematical equation, which is based on the relation between the seismic velocity of water to the seismic velocity obtained in the field （for p-wave velocity only）. The results of this equation which ranged between （30% to 100%） are connected with the results of seismic velocity-porosity relation for saturated sandstone through model, this model can be used for determining the porosity （Φ） and water saturation percentage （SW%） of the sandstones in the same time.展开更多
Invading track of chloride ions and chloride ion distribution rule in cement-based materials were investigated by partially soaking in 3.5% （mass fraction） NaCl solution and fully immerging in 3.5% and 5.0% （mass f...Invading track of chloride ions and chloride ion distribution rule in cement-based materials were investigated by partially soaking in 3.5% （mass fraction） NaCl solution and fully immerging in 3.5% and 5.0% （mass fraction） NaC1 solution, respectively, and relevant invading mechanisms were discussed. Results indicate that under full immerging condition, the invading track of chloride ions in cement mortar is similar to beeline that is vertical to chloride ion invading direction, and chloride ion content decreases rapidly with the increase of chloride ion invading depth. Under partial soaking condition, the invading track of chloride ion in cement mortar is similar to the shape of concave parabola, and chloride ion content decreases slowly along the lengthway direction of cement mortar samples in the distance of 20-80 mm from the bottom. Lots of chloride ions accumulate in cement mortar surface layer under the effect of capillary rise and evaporation and then invade cement mortar by diffusion effect. Under partial soaking condition, cement mortar is distinguished by four areas, i.e., immerging area, wet area, crystallization area and dry area.展开更多
文摘The property of the contact surface between geosynthetics and soil directly affects the whole structure＇s stability. The interface property is one of the most important indices for the reinforced structure. Systematic direct-shear tests with large direct-shear apparatus are carded out for geobelt reinforced clay under different normal stresses and water content. A reinforcement-sand-clay layer system improving the interface behavior greatly is designed. The stress-strain relationship is investigated on the basis of the experimental results. The results show that with the increase of the normal stress, the shear strength between the clay and the reinforcement increases nonlinearly, and with the increase of the water content, the friction coefficient between the clay and the reinforcement decreases dramatically and the cohesion between the clay and the polypropylene geobelt increases initially, then decreases. There is an optimal value for the water content between the clay and the polypropylene geobelt, which is 2% lower than the optimal water content of clay compaction. This reinforcement-sand-clay layer system improves the shear strength of the interface remarkably. Therefore, the clay-sand-reinforcement layer system is a rather good design for practical use in reinforcement engineering.
基金The authors thank the National Natural Science Foundation of China，the Key Laboratory Project of Deep Rock Mechanics
文摘The deep, loose bottom aquifer of the eastern air shaft in the Xinglongzhuang Coal Mine was used to develop an experimental model of shaft grouting through Model deep soil. Lab experiments using chem- ical grouting were done to study the grout. The grouted soil shapes and osmotic pressure were measured during the experiments. The tested characteristics of the grouted soil show that the diffusion mode of grout in saturated sandy soil is a combination of split compaction and osmosis. More specifically, the shape of the grouted soil is determined by split compaction while the size of the grouted soil shape is determined by osmosis. Sensor test results indicate that the main reason for the non-uniform grout diffusion is the anisotropic osmotic pressure field surrounding the grouting holes.
基金financially supported by the National Natural Science Foundation of China (No. 40873015)the Eleventh Five-Year Science and Technology Project of Anhui Province,China(No. 08010302062)
文摘Deep coal mines in northern Anhui province, China, provide opportunities for tracing the distribution and fractionation of rare earth elements CREEs） in deep seated environments. Major ions, as well as REE concentrations were measured in groundwater from a sandstone aquifer located between -400 and -280 m. Our results indicate that this groundwater consists of CI.HCOH-Na or CI.CO3-Na water types with warm temperature （30.1-31.4~C）, circumneutral pH （7.27-8.61） and high levels of total dissolved solids （TDS ~ 1306--2165 mg/L）. Concentrations of REEs in groundwater are high as expressed by their Nd con- centrations （0.0086-0.018μg/L）. Except for weak heavy REEs （HREE） enrichment relative to light REEs （LREE）, the similarity of REE distribution patterns between groundwater and aquifer rock indicate that enrichment of REEs is considered to be controlled by aquifer rock, as well as by their minerals, whereas the fractionation of REEs is controlled by HREE enriched minerals and, to a lesser extent, by inorganic REE complexes. Ce anomalies normalized to Post Archean Average Shale （PAAS） and aquifer rock are weak, which probably reflect the contribution of reduced conditions in combination with pH, rather than a sig- nature of aouifer rock.
文摘This study proposes a model to determine the content of cement in mortars using the background of X-ray diffraction （XRD） spectra taking advantage of the fact that fluorescence radiation for the Cu anticathode is different in cement paste and aggregates, and also that cement paste and aggregates have different crystallinity degrees. The method has been tested for limestone mortars with five different types of cement： I52,5N/SR, CEMII/A-L32,5N, IIIA42,5N/SR, IVA（V）32,5N/SR y CAC.
基金Supported by the Chinese Academy of Sciences (Z110306) and Science and Technology Innovation Fellowship of Hohai University (2001401743)
文摘An experience formula of expansive strain and stone taken from a foundation pit of Hongshanyao Project (HSYP) in Nanjing was described. It is clear that the curve of expansive strain-water content is a logarithm. In the meantime, the relation of expansive strain with time was studied and the importance of expansive stabilization time was illu-minated. The experiment results indicated that the water content has a tremendous effect on peak expansive and steady expansive deformation of swelling red sandstone.
文摘In this paper, a study of sandy soil compaction with different granulometry and moisture content has been performed, and soil mechanical property variations in moisture and granulometry have been investigated. Investigations were performed to compare hydrostatic compression test （HCT） responses and evaluate the compression index, Cc, which is an indicator of the soil＇s susceptibility to compaction-induced damage. The experiments have been performed on 24 soil samples typologies. Each sample has been obtained by combining three types of soil granulometry （types A, B and C） with a relative content varying from 0% to 100% in 20% increments. Soil type A had a granulometry ranging between 0.5 mm and 1 mm, type B between 0.25 mm and 0.5 mm, and type C less than 0.25 mm. These samples were representative of a sandy soil, chemically inactive and had various granulometries and initial moisture contents. A cell for HCT has been set up to allow the initial volume measurement of the test pieces and the subsequent changes during HCT with an estimated error less than 0.1 cm3. All samples were pre-compacted and prepared in agreement with the actual standards. The experimental data are reported in diagrams, the data allowed comparison of the mechanical behaviors between the considered unsaturated soils and underlined how soil moisture and granulometry affect soil response during HCT. Furthermore, because of the methodology used, the equipment was very economical.
文摘The seismic velocities are strongly influenced by porosity and degree of water saturation, as well as other petrophysical properties, such as density and elastic properties of the rocks. In this paper, the saturation of water percentage for sandstones （SW%） has been calculated by mathematical equation, which is based on the relation between the seismic velocity of water to the seismic velocity obtained in the field （for p-wave velocity only）. The results of this equation which ranged between （30% to 100%） are connected with the results of seismic velocity-porosity relation for saturated sandstone through model, this model can be used for determining the porosity （Φ） and water saturation percentage （SW%） of the sandstones in the same time.
基金Project(50678174) supported by the National Natural Science Foundation of China
文摘Invading track of chloride ions and chloride ion distribution rule in cement-based materials were investigated by partially soaking in 3.5% （mass fraction） NaCl solution and fully immerging in 3.5% and 5.0% （mass fraction） NaC1 solution, respectively, and relevant invading mechanisms were discussed. Results indicate that under full immerging condition, the invading track of chloride ions in cement mortar is similar to beeline that is vertical to chloride ion invading direction, and chloride ion content decreases rapidly with the increase of chloride ion invading depth. Under partial soaking condition, the invading track of chloride ion in cement mortar is similar to the shape of concave parabola, and chloride ion content decreases slowly along the lengthway direction of cement mortar samples in the distance of 20-80 mm from the bottom. Lots of chloride ions accumulate in cement mortar surface layer under the effect of capillary rise and evaporation and then invade cement mortar by diffusion effect. Under partial soaking condition, cement mortar is distinguished by four areas, i.e., immerging area, wet area, crystallization area and dry area.
