The plasticity index is an essential design parameter used as a standard input in fine-grained soil investigation programs.It is used to estimate the plasticity and physical properties of soils,and indirectly their st...The plasticity index is an essential design parameter used as a standard input in fine-grained soil investigation programs.It is used to estimate the plasticity and physical properties of soils,and indirectly their strength properties.This index is determined from the Atterberg limit tests,starting from the limits of liquidity and plasticity.However,the realization of the test considered as basic and simple,is not so much.The effects of the operator,the calibration of the apparatus and the environmental aspects during the tests affect the reliability and accuracy of the results.In this paper,the objective is to overcome these difficulties by evaluating the plasticity index of clay and loam soils by considering only the values of the liquid limit.Soil samples were collected from 0 to 5 m depth in the localities of the Khôdepression in Benin.On these samples,Atterberg limit tests were performed in the laboratory.Using MATLAB’s Curve Fitting Toolbox,linear,exponential and power prediction models were analyzed.The results showed that there is indeed a good correlation between the plasticity index and the liquid limit of the soils.For the linear model,it was observed R2 equal to 0.9891.For the exponential model,R2 is 0.98871 and for the power model 0.9802.A study of the residual plot validated the models found,as well as comparisons with well-known literature sources.Through the equations obtained,it is now possible to study the plasticity of soils in the Khôdepression only from the liquid limit,without determining the plasticity limit.展开更多
In order to explore the effects of moisture content and plasticity index on Duncan-Chang model parameters?K,n,?C?and?Rf,?we selected 8 groups of soft soil with water content of 69.1%?-?94.3% and plasticity index of 32...In order to explore the effects of moisture content and plasticity index on Duncan-Chang model parameters?K,n,?C?and?Rf,?we selected 8 groups of soft soil with water content of 69.1%?-?94.3% and plasticity index of 32.2?-?54.1 for triaxial unconsolidated undrained shear test. The results show that?Cuu,?K?and?n?values all showed a downward trend, and?Rf?variation was not obvious with the increase of moisture content. The variation rule of each parameter is not obvious with the increase of plasticity index. When moisture content is constant,?Cuu?and?n?values do not change much,?K?increases with the increase of plasticity index within the range of 70%?-?80% moisture content, and does not change much with the increase of plasticity index when moisture content is greater than 80%,?Rf?has no obvious rule.?When the plasticity index is constant,?Cuu,?Kand?n?decrease with the increase of moisture content,?Rf?has no obvious rule. The maximum value of?Cuu?is 20.18?kPa, the minimum is 3.72?kPa, and the maximum to minimum ratio is 5.42. The maximum value of?K?is 0.517, the minimum is 0.022, and the maximum to minimum ratio is 23.5. The maximum value of?n?is 1.198, the minimum is 0.150, and the maximum to minimum ratio is 7.99. The maximum value of?Rf?is 0.872, the minimum is 0.679, and the maximum to minimum ratio is 1.28.展开更多
The amount of fine material available in the soil is significant in Atterberg limits and methylene blue tests. In the context of Atterberg limits, increased amount of clay minerals contained in the soil increases liqu...The amount of fine material available in the soil is significant in Atterberg limits and methylene blue tests. In the context of Atterberg limits, increased amount of clay minerals contained in the soil increases liquid and plastic limit values;however, increasing sand content reduces the moisture content reducing the water retention capacity of the soil which in return reduces the plasticity index (PI) value. In the case of methylene blue test, which is used to specify the quality of the amount of fine material, existence of clay in the medium increases the pollution level of the sand and the amount of methylene solution (V1) used. In this study, soil classes were determined and pollution rates were identified with Atterberg limits, pycnometer, sieve analysis, hydrometer analysis and methylene blue tests conducted on 11 different natural soil samples collected from different regions. From the data obtained, first the relationship between PI and methylene blue (MB) was examined and was evaluated according to the results of the “single regression” method. Furthermore, the other coefficient of uniformity (Cu), coefficient of graduation (Cc), unit weight of soils (γs) parameters obtained from experimental studies were also subjected to “multiple regression analysis” in order to reveal their impact on the MB and this impact was confirmed taking both statistical analyses into account.展开更多
Measurement of a production unit-performance is crucial in determining whether it has achieved its objectives or not, and it generates a phase of management process that consists of feedback motivation phases. The pur...Measurement of a production unit-performance is crucial in determining whether it has achieved its objectives or not, and it generates a phase of management process that consists of feedback motivation phases. The purpose of this paper is to analyze the growth potentials of five production machines in a Jordanian company for plastic industries by employing the non-parametric Malmquist productivity index (MPI) over the period from February to July 2014 in both day and night shifts. The productivity change is decomposed into technical efficiency change (TEC) and technological change (TC). Inefficiency values are observed in each period. The percentage of input utilization is determined in all periods. Then, the Malmquist productivity index (MPI) values are calculated for all periods. Finally, comparisons of TEC, TC and MPI are conducted among the five machines and between the day and night shifts for each machine. The MPI results indicate that the needs for internal training, effective operating procedures, and enhancing quality procedures are required to increase the technical efficiency. On the other hand, figuring out more efficient ways of making existing products allowing output to grow at a faster rate than economic inputs, like using new technologies, will increase technological change. In conclusions, Malmquist model analysis shall provide valuable reference information to management when evaluating the progress in the performances of production machines in plastic industry.展开更多
Dredged soil and phosphogypsum are frequently regarded as wasted materials,which require further treatment to control their environmental impact.Hence,phosphogypsum is proposed as a binder to stabilize dredged soil,ai...Dredged soil and phosphogypsum are frequently regarded as wasted materials,which require further treatment to control their environmental impact.Hence,phosphogypsum is proposed as a binder to stabilize dredged soil,aiming at efficiently reducing and reusing these waste materials.In this study,the engineering properties of cement-phosphogypsum stabilized dredged soils were investigated through a series of unconfined compression tests,and the effects of plasticity index of original soils on the strength improvement were identified.Then,the microstructure test and mineralogical test were performed to understand the mechanism of physical role of original soils in strength improvement.The results revealed that the unconfined compressive strength significantly decreased with the increase in plasticity index at the same binder content.The essential factor for strength improvement was found to be the formation of cementitious materials identified as calcium silicate hydrate(CSH),calcium aluminate hydrate(CAH),and ettringite(Aft).The normalized integrated intensity of cementitious materials(CSH+CAH+Aft)by pore volume decreased with the increase in plasticity index.Consequently,the density of cementitious materials filling the soil pores controlled the effectiveness of strength improvement.More cementitious materials per pore volume were observed for the original soils with lower values of plasticity index.That is,the higher strength of stabilized soils with lower values of plasticity index was attributed to a packed structure forming by integrated fabric through denser cementitious components.It can be anticipated from the above findings that the effectiveness of stabilization treatment will significantly reduce with the increase in plasticity of origin soil.展开更多
Bruguiera sexangula(Lour.)Poir is an exclusive evergreen mangrove species to the Sundarbans of Bangladesh.It grows well in moderate saline zones with full sunlight.This study presents leaf morphological plasticity in ...Bruguiera sexangula(Lour.)Poir is an exclusive evergreen mangrove species to the Sundarbans of Bangladesh.It grows well in moderate saline zones with full sunlight.This study presents leaf morphological plasticity in B.sexangula to saline zones.Leaves were sampled from different saline zones and various morphological traits were measured.The results exposed a wide deviations of leaf size parameters:leaf length varied 6.6–17.3 cm;width 2.7–7.8 cm;upper quarter width 2.2–6.5 cm;down quarter width 2.5–7.3 cm;and petiole length 0.17–1.43 cm.Leaf length was significantly larger in fresh water than in other salinity zones,whereas,leaf width,upper and lower leaf quarters were significantly larger in medium saline zone.Leaf shape parameters showed a large variation among saline zones.Leaf base angle was significantly larger in both medium and strong salinity zones.Tip angle was significantly greater in medium salinity zone.Leaf perimeter was significantly larger in fresh water but leaf area was significantly bigger in medium saline zone.Leaf index and specific leaf area were maximum in moderate saline zone.Plasticity index was the highest in moderate saline for almost all the parameters presented.The ordination(PCA)showed clusters of leaf samples although there were some overlap among them which suggested a salt-stress relationship among salinity zones.The results indicate that B.sexangula had a plasticity strategy on leaf morphological parameters to salinity in the Sundarbans.This study will provide basic information of leaf plasticity of this species among saline zones which will help for site selection of coastal planting and will also provide information for policy makers to take necessary steps for its conservation.展开更多
Conical picks are by far the most widely used drag type cutting tools employed on partial face rock excavation machines.The cutting force and specific energy are two important design parameters for the conical pick pe...Conical picks are by far the most widely used drag type cutting tools employed on partial face rock excavation machines.The cutting force and specific energy are two important design parameters for the conical pick performance,and the rock cutting testing is considered as the promising tool for determining these parameters.In the absence of an instrumented cutting rig,researchers generally rely on empirical predictive plots.For this,this paper suggests predictive plots for estimating the cutting force and specific energy,in consideration of the cutting depth to define the cuttability with conical picks.In this context,rock cutting tests were carried out on six volcanic rock samples with varying cutting depths using the unrelieved and relieved cutting modes.The cutting force and specific energy were correlated with the uniaxial compressive strength,Brazilian tensile strength,elasticity modulus,and plasticity index.Predictive plots were proposed for different cutting depths in the unrelieved and relieved cutting modes and exponential relationships were obtained among the cuttability parameters,and mechanical and elastoplastic properties of rocks.展开更多
文摘The plasticity index is an essential design parameter used as a standard input in fine-grained soil investigation programs.It is used to estimate the plasticity and physical properties of soils,and indirectly their strength properties.This index is determined from the Atterberg limit tests,starting from the limits of liquidity and plasticity.However,the realization of the test considered as basic and simple,is not so much.The effects of the operator,the calibration of the apparatus and the environmental aspects during the tests affect the reliability and accuracy of the results.In this paper,the objective is to overcome these difficulties by evaluating the plasticity index of clay and loam soils by considering only the values of the liquid limit.Soil samples were collected from 0 to 5 m depth in the localities of the Khôdepression in Benin.On these samples,Atterberg limit tests were performed in the laboratory.Using MATLAB’s Curve Fitting Toolbox,linear,exponential and power prediction models were analyzed.The results showed that there is indeed a good correlation between the plasticity index and the liquid limit of the soils.For the linear model,it was observed R2 equal to 0.9891.For the exponential model,R2 is 0.98871 and for the power model 0.9802.A study of the residual plot validated the models found,as well as comparisons with well-known literature sources.Through the equations obtained,it is now possible to study the plasticity of soils in the Khôdepression only from the liquid limit,without determining the plasticity limit.
文摘In order to explore the effects of moisture content and plasticity index on Duncan-Chang model parameters?K,n,?C?and?Rf,?we selected 8 groups of soft soil with water content of 69.1%?-?94.3% and plasticity index of 32.2?-?54.1 for triaxial unconsolidated undrained shear test. The results show that?Cuu,?K?and?n?values all showed a downward trend, and?Rf?variation was not obvious with the increase of moisture content. The variation rule of each parameter is not obvious with the increase of plasticity index. When moisture content is constant,?Cuu?and?n?values do not change much,?K?increases with the increase of plasticity index within the range of 70%?-?80% moisture content, and does not change much with the increase of plasticity index when moisture content is greater than 80%,?Rf?has no obvious rule.?When the plasticity index is constant,?Cuu,?Kand?n?decrease with the increase of moisture content,?Rf?has no obvious rule. The maximum value of?Cuu?is 20.18?kPa, the minimum is 3.72?kPa, and the maximum to minimum ratio is 5.42. The maximum value of?K?is 0.517, the minimum is 0.022, and the maximum to minimum ratio is 23.5. The maximum value of?n?is 1.198, the minimum is 0.150, and the maximum to minimum ratio is 7.99. The maximum value of?Rf?is 0.872, the minimum is 0.679, and the maximum to minimum ratio is 1.28.
文摘The amount of fine material available in the soil is significant in Atterberg limits and methylene blue tests. In the context of Atterberg limits, increased amount of clay minerals contained in the soil increases liquid and plastic limit values;however, increasing sand content reduces the moisture content reducing the water retention capacity of the soil which in return reduces the plasticity index (PI) value. In the case of methylene blue test, which is used to specify the quality of the amount of fine material, existence of clay in the medium increases the pollution level of the sand and the amount of methylene solution (V1) used. In this study, soil classes were determined and pollution rates were identified with Atterberg limits, pycnometer, sieve analysis, hydrometer analysis and methylene blue tests conducted on 11 different natural soil samples collected from different regions. From the data obtained, first the relationship between PI and methylene blue (MB) was examined and was evaluated according to the results of the “single regression” method. Furthermore, the other coefficient of uniformity (Cu), coefficient of graduation (Cc), unit weight of soils (γs) parameters obtained from experimental studies were also subjected to “multiple regression analysis” in order to reveal their impact on the MB and this impact was confirmed taking both statistical analyses into account.
文摘Measurement of a production unit-performance is crucial in determining whether it has achieved its objectives or not, and it generates a phase of management process that consists of feedback motivation phases. The purpose of this paper is to analyze the growth potentials of five production machines in a Jordanian company for plastic industries by employing the non-parametric Malmquist productivity index (MPI) over the period from February to July 2014 in both day and night shifts. The productivity change is decomposed into technical efficiency change (TEC) and technological change (TC). Inefficiency values are observed in each period. The percentage of input utilization is determined in all periods. Then, the Malmquist productivity index (MPI) values are calculated for all periods. Finally, comparisons of TEC, TC and MPI are conducted among the five machines and between the day and night shifts for each machine. The MPI results indicate that the needs for internal training, effective operating procedures, and enhancing quality procedures are required to increase the technical efficiency. On the other hand, figuring out more efficient ways of making existing products allowing output to grow at a faster rate than economic inputs, like using new technologies, will increase technological change. In conclusions, Malmquist model analysis shall provide valuable reference information to management when evaluating the progress in the performances of production machines in plastic industry.
基金supported by the National Natural Science Foundation of China(Grant Nos.52178328 and 52178361)Partial financial support from the Open-end Research Fund of State Key Laboratory for Geomechanics and Deep Underground Engineering(Grant No.SKLGDUEK2114)。
文摘Dredged soil and phosphogypsum are frequently regarded as wasted materials,which require further treatment to control their environmental impact.Hence,phosphogypsum is proposed as a binder to stabilize dredged soil,aiming at efficiently reducing and reusing these waste materials.In this study,the engineering properties of cement-phosphogypsum stabilized dredged soils were investigated through a series of unconfined compression tests,and the effects of plasticity index of original soils on the strength improvement were identified.Then,the microstructure test and mineralogical test were performed to understand the mechanism of physical role of original soils in strength improvement.The results revealed that the unconfined compressive strength significantly decreased with the increase in plasticity index at the same binder content.The essential factor for strength improvement was found to be the formation of cementitious materials identified as calcium silicate hydrate(CSH),calcium aluminate hydrate(CAH),and ettringite(Aft).The normalized integrated intensity of cementitious materials(CSH+CAH+Aft)by pore volume decreased with the increase in plasticity index.Consequently,the density of cementitious materials filling the soil pores controlled the effectiveness of strength improvement.More cementitious materials per pore volume were observed for the original soils with lower values of plasticity index.That is,the higher strength of stabilized soils with lower values of plasticity index was attributed to a packed structure forming by integrated fabric through denser cementitious components.It can be anticipated from the above findings that the effectiveness of stabilization treatment will significantly reduce with the increase in plasticity of origin soil.
基金supported by JSPS RONPAKU Program FY2018,Japan(R11810)Bangladesh University Grants Commission(UGC/SciTech/Agri(Crop-47)-26/2017/4915)。
文摘Bruguiera sexangula(Lour.)Poir is an exclusive evergreen mangrove species to the Sundarbans of Bangladesh.It grows well in moderate saline zones with full sunlight.This study presents leaf morphological plasticity in B.sexangula to saline zones.Leaves were sampled from different saline zones and various morphological traits were measured.The results exposed a wide deviations of leaf size parameters:leaf length varied 6.6–17.3 cm;width 2.7–7.8 cm;upper quarter width 2.2–6.5 cm;down quarter width 2.5–7.3 cm;and petiole length 0.17–1.43 cm.Leaf length was significantly larger in fresh water than in other salinity zones,whereas,leaf width,upper and lower leaf quarters were significantly larger in medium saline zone.Leaf shape parameters showed a large variation among saline zones.Leaf base angle was significantly larger in both medium and strong salinity zones.Tip angle was significantly greater in medium salinity zone.Leaf perimeter was significantly larger in fresh water but leaf area was significantly bigger in medium saline zone.Leaf index and specific leaf area were maximum in moderate saline zone.Plasticity index was the highest in moderate saline for almost all the parameters presented.The ordination(PCA)showed clusters of leaf samples although there were some overlap among them which suggested a salt-stress relationship among salinity zones.The results indicate that B.sexangula had a plasticity strategy on leaf morphological parameters to salinity in the Sundarbans.This study will provide basic information of leaf plasticity of this species among saline zones which will help for site selection of coastal planting and will also provide information for policy makers to take necessary steps for its conservation.
文摘Conical picks are by far the most widely used drag type cutting tools employed on partial face rock excavation machines.The cutting force and specific energy are two important design parameters for the conical pick performance,and the rock cutting testing is considered as the promising tool for determining these parameters.In the absence of an instrumented cutting rig,researchers generally rely on empirical predictive plots.For this,this paper suggests predictive plots for estimating the cutting force and specific energy,in consideration of the cutting depth to define the cuttability with conical picks.In this context,rock cutting tests were carried out on six volcanic rock samples with varying cutting depths using the unrelieved and relieved cutting modes.The cutting force and specific energy were correlated with the uniaxial compressive strength,Brazilian tensile strength,elasticity modulus,and plasticity index.Predictive plots were proposed for different cutting depths in the unrelieved and relieved cutting modes and exponential relationships were obtained among the cuttability parameters,and mechanical and elastoplastic properties of rocks.