Using soil data of the Second National Field Survey,the soil fertility of wetland ecosystem of Dongting Lake was evaluated by using the technology of GIS and method of fuzzy evaluation.Integrated with the wetland actu...Using soil data of the Second National Field Survey,the soil fertility of wetland ecosystem of Dongting Lake was evaluated by using the technology of GIS and method of fuzzy evaluation.Integrated with the wetland actuality of Dongting Lake and particularity of paddy,seven factors (including soil organic matter,total nitrogen,total phosphorus,total potassium,available phosphorus,available potassium,and pH value),closely related with soil fertility,were chosen to establish the index system of synthetical evaluation.Based on the effect degree of each selected index on soil fertility,a judgment matrix was built,and the weight coefficient was determined by the method of correlation coefficient.Finally,under the support of the spatial analysis module of GIS (Geographic Information System),the spatial distribution properties of soil fertility in wetland ecosystem of Dongting Lake were studied.The results show that the soil fertility of Dongting Lake wetland ecosystem is not very good,and the area of type III and type IV achieves 69.8%.As a result,many countermeasures should be taken to improve the soil fertility.As for the spatial properties,the soil fertility level of central and west Dongting Lake is much higher than that of north and south part.The soil fertility of paddy field surpasses that of red soil,and the contents of soil organic matter and total nitrogen in paddy field are large.展开更多
The suitability of five methods was discussed here,taking the typical results from in-situ load test of Renshou Mansion and Caifu Plaza in Yueyang City for example.It shows that bearing capacity can be obtained by the...The suitability of five methods was discussed here,taking the typical results from in-situ load test of Renshou Mansion and Caifu Plaza in Yueyang City for example.It shows that bearing capacity can be obtained by the proportion load and limit load from p-s curve with the first and the second point of contraflexure easily.It is recommended that the accurate value of bearing capacity can be obtained by hyperbola fitting method and minimum curvature radius method theoretically.The rebound method is clear in principle,in which the elastoplasticity characteristic is thought about.Out of consideration for the unsteadiness and unobviousness of bearing capacity from relative settlement method,it can be only adopted as reference.So bearing capacity of soft rock ground should be determined by weathering condition of soft rock and curve type.展开更多
In this communication we start both from a trirectangular trihedral defined by the three coordinate planes and a fourth plane, called the chart or projection, which contains the vertex of the trihedral above. Later we...In this communication we start both from a trirectangular trihedral defined by the three coordinate planes and a fourth plane, called the chart or projection, which contains the vertex of the trihedral above. Later we define the main related views or trihedral views as those produced by the tilt of the three coordinate planes to the outside of their trihedral on the chart plane. For each projection plane there are some unique main related views, regardless of the projection direction. In turn, from the trihedral views we can obtain the axonometric perspective from which they come. These properties can simplify some graphic constructions of the axonometric system, for example, determine the projections of the axes from the main related views or determine the axonometric scales from the axes. It is considered that this new definition of related views allows a simplification as to the understanding of the representation systems and it is intended to be suitable for teaching purposes and programming.展开更多
Combined with a proposed homogeneous earth dam in deep cladding foundation, Duncan E-B model is applied to simulate dam-filled material, apply to three-dimensional nonlinear finite element method, attain the stress-st...Combined with a proposed homogeneous earth dam in deep cladding foundation, Duncan E-B model is applied to simulate dam-filled material, apply to three-dimensional nonlinear finite element method, attain the stress-strain distribution and alteration in concrete cutoff wall in completion and water storage periods, analysis the stress state in the contact element between concrete cutoff wall and cladding foundation, provide the corresponding measures. The calculation results show that the design of concrete cutoff wall and homogeneous earth dam is reasonable.展开更多
基金Projects(40971170,51039001) supported by the National Natural Science Foundation of ChinaProject(2007AA10Z222) supported by the National High Technology Research and Development Program of China
文摘Using soil data of the Second National Field Survey,the soil fertility of wetland ecosystem of Dongting Lake was evaluated by using the technology of GIS and method of fuzzy evaluation.Integrated with the wetland actuality of Dongting Lake and particularity of paddy,seven factors (including soil organic matter,total nitrogen,total phosphorus,total potassium,available phosphorus,available potassium,and pH value),closely related with soil fertility,were chosen to establish the index system of synthetical evaluation.Based on the effect degree of each selected index on soil fertility,a judgment matrix was built,and the weight coefficient was determined by the method of correlation coefficient.Finally,under the support of the spatial analysis module of GIS (Geographic Information System),the spatial distribution properties of soil fertility in wetland ecosystem of Dongting Lake were studied.The results show that the soil fertility of Dongting Lake wetland ecosystem is not very good,and the area of type III and type IV achieves 69.8%.As a result,many countermeasures should be taken to improve the soil fertility.As for the spatial properties,the soil fertility level of central and west Dongting Lake is much higher than that of north and south part.The soil fertility of paddy field surpasses that of red soil,and the contents of soil organic matter and total nitrogen in paddy field are large.
基金National Natural Science Foundation of China(No.50874043)Scientific Research Fund of Hunan Province Education Department(No.09A028)Scientific Research Foundation for Returned Scholars,Ministry of Education of China(No.[2007]1108)
文摘The suitability of five methods was discussed here,taking the typical results from in-situ load test of Renshou Mansion and Caifu Plaza in Yueyang City for example.It shows that bearing capacity can be obtained by the proportion load and limit load from p-s curve with the first and the second point of contraflexure easily.It is recommended that the accurate value of bearing capacity can be obtained by hyperbola fitting method and minimum curvature radius method theoretically.The rebound method is clear in principle,in which the elastoplasticity characteristic is thought about.Out of consideration for the unsteadiness and unobviousness of bearing capacity from relative settlement method,it can be only adopted as reference.So bearing capacity of soft rock ground should be determined by weathering condition of soft rock and curve type.
文摘In this communication we start both from a trirectangular trihedral defined by the three coordinate planes and a fourth plane, called the chart or projection, which contains the vertex of the trihedral above. Later we define the main related views or trihedral views as those produced by the tilt of the three coordinate planes to the outside of their trihedral on the chart plane. For each projection plane there are some unique main related views, regardless of the projection direction. In turn, from the trihedral views we can obtain the axonometric perspective from which they come. These properties can simplify some graphic constructions of the axonometric system, for example, determine the projections of the axes from the main related views or determine the axonometric scales from the axes. It is considered that this new definition of related views allows a simplification as to the understanding of the representation systems and it is intended to be suitable for teaching purposes and programming.
文摘Combined with a proposed homogeneous earth dam in deep cladding foundation, Duncan E-B model is applied to simulate dam-filled material, apply to three-dimensional nonlinear finite element method, attain the stress-strain distribution and alteration in concrete cutoff wall in completion and water storage periods, analysis the stress state in the contact element between concrete cutoff wall and cladding foundation, provide the corresponding measures. The calculation results show that the design of concrete cutoff wall and homogeneous earth dam is reasonable.
