From an analysis of the relationships of grouting coefficients under the conditions of grouting reducing subsidence, it is concluded that the reducing subsidence rate is in direct proportion to the grouting-recovery r...From an analysis of the relationships of grouting coefficients under the conditions of grouting reducing subsidence, it is concluded that the reducing subsidence rate is in direct proportion to the grouting-recovery ratio, and its proportional coefficient depends on the coefficient of reducing subsidence and collapsing coefficient.The coefficient for reducing subsidence volume φ=ΔV/V_(ash) is related to overburden lithology.The coefficient for reducing subsidence volume φ is always larger than 1.This improves the reducing subsidence rate,the grouting-recovery ratio, and the coefficient for reducing subsidence volume, which can maximize the control of surface subsidence.展开更多
This article first talks about railways in general and ballast in particular. An inventory is then made on the modernization of the Senegalese ballast railways. In the second phase, an experimental work of characteriz...This article first talks about railways in general and ballast in particular. An inventory is then made on the modernization of the Senegalese ballast railways. In the second phase, an experimental work of characterization of basaltic aggregates of Diack (Locality of Ngoundiane, Thiès region, Senegal) is presented. The grain size studied is 25/50 mm as for any material studied for use as railway ballast. Experimental work presented consists of the characterization of the shape of an aggregate using the NF P 18-301 standard. The test consists of comparing the volume of the aggregate to that of an equivalent sphere with the largest diameter of the aggregate, by calculating the average volume coefficient. With a Representative Elementary Volume (REV) of 6 aggregates, the volume coefficient “C<sub><span style="font-family:Verdana;">v</span></sub><span style="font-family:Verdana;">” fluctuates between 0.27 and 0.49 with an average volume coefficient of 0.39 which is well above 0.15</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">. </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The grains studied are polyhedral and therefore have a high mechanical resistance.</span></span></span>展开更多
The shapes of block within the rock mass have an important effect on the rock properties, so it＇s very important to evaluate the shapes of rock fragmentation and to determine the geometric characteristics distributio...The shapes of block within the rock mass have an important effect on the rock properties, so it＇s very important to evaluate the shapes of rock fragmentation and to determine the geometric characteristics distribution of the block. The previous methods to classify rock block shape are based on the assumption that a block shape is approximately orthogonal, which is acceptable in only a few rock masses. This paper proposes a new method for block shape classification using triangular diagram together with parameters of co-linearity e and volume coefficient K, which combines the shape categorization with block volume for statistical analysis. Rock block equivalent size calculation methods based on block shape is proposed and the block cumulative percentage of total volume statistical analysis is given. In order to verify this block shape classification method, three ideal rock masses with approximately orthogonal joint sets have been generated and simulated.展开更多
Solar envelope is a concept for regulating solar access in urban planning.It is a roof-like imaginary surface over a given piece of land that controls the maximum allowed building height in order to avoid casting shad...Solar envelope is a concept for regulating solar access in urban planning.It is a roof-like imaginary surface over a given piece of land that controls the maximum allowed building height in order to avoid casting shadows on the neighbours during a specific period.The volume of solar envelopes regulates building density,depending on geo-metric attributes and time(plot size and proportions,orientation,ground slope,latitude,duration of insolation).This work compares the effect of such factors on the size of solar envelopes on a variety of land parcels,individually or in groups.Repeated applications of solid modelling are used to calculate in each case the values of‘Solar Volume Coefficient’,i.e.the volume of a solar envelope per unit of its base as a measure for comparisons.Results show the influence of the various factors affecting the geometry of solar envelopes.Among other findings,it is also shown that solar envelopes gener-ate urban densities lower than conventional urban regulations.The total volume of solar envelopes over an area(‘Solar Building Potential’)can be increased by raising the reference level of solar envelopes(‘shadow fence’or‘solar fence’).Lower urban densities are compensated by facilitating solar applications,as well as by enhancing daylight,ventilation,and vistas in the urban context,thus creating new‘solar cityscapes’exem-plified here on existing street patterns.展开更多
基金Supported by the National Natural Science Foundation of China (50174035, 50474029)
文摘From an analysis of the relationships of grouting coefficients under the conditions of grouting reducing subsidence, it is concluded that the reducing subsidence rate is in direct proportion to the grouting-recovery ratio, and its proportional coefficient depends on the coefficient of reducing subsidence and collapsing coefficient.The coefficient for reducing subsidence volume φ=ΔV/V_(ash) is related to overburden lithology.The coefficient for reducing subsidence volume φ is always larger than 1.This improves the reducing subsidence rate,the grouting-recovery ratio, and the coefficient for reducing subsidence volume, which can maximize the control of surface subsidence.
文摘This article first talks about railways in general and ballast in particular. An inventory is then made on the modernization of the Senegalese ballast railways. In the second phase, an experimental work of characterization of basaltic aggregates of Diack (Locality of Ngoundiane, Thiès region, Senegal) is presented. The grain size studied is 25/50 mm as for any material studied for use as railway ballast. Experimental work presented consists of the characterization of the shape of an aggregate using the NF P 18-301 standard. The test consists of comparing the volume of the aggregate to that of an equivalent sphere with the largest diameter of the aggregate, by calculating the average volume coefficient. With a Representative Elementary Volume (REV) of 6 aggregates, the volume coefficient “C<sub><span style="font-family:Verdana;">v</span></sub><span style="font-family:Verdana;">” fluctuates between 0.27 and 0.49 with an average volume coefficient of 0.39 which is well above 0.15</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">. </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The grains studied are polyhedral and therefore have a high mechanical resistance.</span></span></span>
基金supported by the Yunnan Provincial College and Institute Science and Technology Cooperation Projects (Grant No.2006YX26)the Technological Innovation and Technical Development Special Projects in Yunnan Province (Grant No.2007GA007)
文摘The shapes of block within the rock mass have an important effect on the rock properties, so it＇s very important to evaluate the shapes of rock fragmentation and to determine the geometric characteristics distribution of the block. The previous methods to classify rock block shape are based on the assumption that a block shape is approximately orthogonal, which is acceptable in only a few rock masses. This paper proposes a new method for block shape classification using triangular diagram together with parameters of co-linearity e and volume coefficient K, which combines the shape categorization with block volume for statistical analysis. Rock block equivalent size calculation methods based on block shape is proposed and the block cumulative percentage of total volume statistical analysis is given. In order to verify this block shape classification method, three ideal rock masses with approximately orthogonal joint sets have been generated and simulated.
文摘Solar envelope is a concept for regulating solar access in urban planning.It is a roof-like imaginary surface over a given piece of land that controls the maximum allowed building height in order to avoid casting shadows on the neighbours during a specific period.The volume of solar envelopes regulates building density,depending on geo-metric attributes and time(plot size and proportions,orientation,ground slope,latitude,duration of insolation).This work compares the effect of such factors on the size of solar envelopes on a variety of land parcels,individually or in groups.Repeated applications of solid modelling are used to calculate in each case the values of‘Solar Volume Coefficient’,i.e.the volume of a solar envelope per unit of its base as a measure for comparisons.Results show the influence of the various factors affecting the geometry of solar envelopes.Among other findings,it is also shown that solar envelopes gener-ate urban densities lower than conventional urban regulations.The total volume of solar envelopes over an area(‘Solar Building Potential’)can be increased by raising the reference level of solar envelopes(‘shadow fence’or‘solar fence’).Lower urban densities are compensated by facilitating solar applications,as well as by enhancing daylight,ventilation,and vistas in the urban context,thus creating new‘solar cityscapes’exem-plified here on existing street patterns.
