广西桉树林取代马尾松林对植物多样性的影响

对广西钦州市马尾松林和巨尾桉人工林的植物多样性开展研究,旨在阐明桉树林取代马尾松林对植物多样性和植物功能群的影响,促进对桉树人工林的科学认知。研究表明,采伐马尾松林种植桉树后10年,在1 800 m2样地内,桉树林的物种数为95～98种（木本植物50种,藤本17～19种,草本24～28种）,而马尾松林为63～88种（木本植物32～48种,藤本13～24种,草本16种）,两类林分的木本、藤本和总物种数差异不显著（P为0.237～0.937）,而草本植物差异显著（P=0.038）,表明桉树林取代马尾松林将显著增加草本植物的物种丰富度。桉树林取代马尾松林对铁芒萁有显著的负效应,重要值减少50%（P=0.077）,而对五节芒（P=0.057）和东方乌毛蕨（P=0.079）有显著的正效应,重要值提高0.85～3.76倍。桉树林和马尾松林木本植物的Shannon Wiener指数(H′)、Simpson指数(D)和均匀度指数(Jsw)差异不显著（P为0.299～0.957）,而草本植物的H′、D和Jsw差异极显著（P≤0.002）。桉树林取代马尾松林对群落的物种多样性和功能群具有显著的影响,然而,桉树人工林建立过程中采取的采伐、炼山、整地、施肥等措施是导致群落物种多样性和功能群变化的主要原因。      

福建省山地坡面风景游憩林单因素美景度评价研究

风景游憩林美景度评价结果可用于指导风景游憩林的构建,也可为建立风景游憩林美学特征和审美态度的心理物理模型积累基础研究数据。采用美景度评判法（scenic beauty estimation,SBE）对福建省山地坡面风景游憩林进行分析,结果表明:风景游憩林的质地、冠形的可辨度、统一度和对比度、斑块边界线、树种组成及年龄结构、群落垂直结构、混交方式等对森林风景的美景度均有一定影响。并根据评价结果提出福建省山地坡面风景游憩林的构建技术,包括斑块质地的构建、斑块边界线的构建、不同林分年龄风景游憩林管理、群落垂直结构管理、树种组成及配置等。      

A Highly Activated Mineral Admixture Slurry Consisting of a Wet discharged Fly ash and Carbide Lime Composite

To recycle wet discharged fly ash and carbide lime effectively, a highly activated mineral admixture slurry consisting of both these components was investigated. The preparation technology of mineral admixture slurry made from a composite of wet discharged fly ash and carbide lime and the strengths, hydration products change (XRD, SEM) of cement paste made by the slurry were studied. The results indicate that the optimal proportion between wet discharged fly ash and carbide lime (solid content) is 75:25 in the process of wet milling preparation. The alkaline environment provided by carbide lime with high Ca(OH)2content and cement hydration accelerated by modified agents can promote early activation of fly ash, and accelerate its secondary hydration reaction.     

Effect of Microorganisms on Some Engineering Properties of Silt

The microbiology was introduced in foundation treatment. Several Carbonate mineralization microorganisms and polysaccharides viscose microorganisms were screened and the microorganisms No.ATCC 6453,3,polysaccharides viscose microorganisms 5 and 6 were used in silt modification. The engineering properties of silt before and after modification were compared by unconfined compressive strength test and indoor seepage test. The microstructures of silt incorporating different microorganisms were analysed by mean of scanning electron microscope and energy dispersive X ray (EDX) analysis. And the modification mechanism of silt has been revealed. These studies indicate that certain engineering properties of silt can be improved by incorporating microorganisms.     

Analysis on Influence of Fault Location and Strength on Deformation and Stress Distribution of Surrounding Rocks of Large Underground Openings

The stability of rock mass project is mainly controlled by the rock mass structure, and faults are the large geological discontinuity plane commonly encountered in rock mass engineering. The stability of surrounding rocks is restricted by mechanical property and location to underground cavern of faults, the detailed studies carried out by analysis of numerical calculation and construction monitoring datum of underground powerhouse of Three Gorges Project show: the distribution of stress and deformation of surrounding rock masses containing a fault are badly deteriorated, the distribution of stress and deformation are obviously different under different natural stress field and position of fault; The influence of friction strength of fault on deformation of surrounding rocks is more obvious when a fault is located near the crown, but the cohesion is more when wall nearby, and the influence is more distinct with side pressure coefficient increases.     

Quantitative Analysis of Influencing Factors for Settlement Generation

In the research of settlement renovation nowadays, because of the lack of a quantitative analysis, it was difficult to get a scientific, reasonable, systemic quantitative conclusion. This paper is presented to build a scientific,systemic and quantitative analysis method through which many influence factors invloved in the research of settlement, such as physical environment, social behavior and relatoins among these factors were quantitatively analyzed to get a system with generative simulation in the whole and detailed quantitative analysis for each individual factor, and to make the communication and judgement of the result easy.      

Discussion on Calculation Pattern of Concrete Filled Steel Tube with Dumbbell shaped Section

Based on the structural feature of dumbbell shaped section of concrete filled steel tube (CFST), a combined spatial beam element is presented. In this structure, two steel tubes, two core concretes, one web and the concrete in web cavity are firstly considered as general spatial beam elements, then they are assembled into a spatial combined beam element according to the plane hypothesis and transformation matrix formed from master and slave nodes. A FORTRAN program for CFST arch with dumbbell shaped section has been developed, and the numerical example shows that the steel tubes and core concretes bear mainly the axial forces with small moments, thus, a modified formula for lattice column method to calculate axial forces of the upper and lower limbs of CFST with dumbbell shaped section is deduced. Comparison of the results from the modified formula with those from an example indicates that the modified formula gives relatively accurate results.      

A Land Use Model for Urban Rail Station Area Planning Based on TOD Strategy

Transit oriented development (TOD) presents a sustainable urban development strategy by creating an efficient integration of land use and public transit. A TOD planning model for the land use of urban rail station area was explored by means of a multiple objective mathematical programming model. Three objectives were considered: encouraging transit system volume, promoting livable communities, and balancing land use. The model can easily be solved by transforming it into a linear multi programming problem. The Xujiahui rail rapid transit station area in Shanghai is chosen as case study to illustrate the model application and planning results. The result indicates that the model would be efficient in practice.     

Torsion behavior of Steel encased Concrete Composite Beams

In order to study torsion behavior of steel encased concrete composite beams, experiments were carried out with eight specimens. The destruction shape, working mechanism and the crack development and distribution were analyzed under pure torsion and combine torsion conditions. And also the relationships were investigated between torque and torsion ratio, load and strain, bending moment and deflection and load crack. On the basis of elasticity plastic theory, the formulas of cracking torsion were presented for pure torsion and combined torsion of combined beam. And with spatial truss model of variable angle, formulas for ultimate torsion strength of pure torsion and combined torsion were put forward. The predicted results were in good agreement with measured ones. The proposed formulas provided basis for evaluating safety and stability of the structural.     

Damage Evolution and Acoustic Emission Character of Coalrock under Unloading Condition

The damage failure mechanisms of coalrock under unloading condition during deep mining is different from those under traditional loading condition, starting from the unloading condition position to study the dynamic disaster of coalrock has become a new direction in the disaster study. The rock mechanics electrohydraulic servo test system (MTS815) and acoustic emission system (8CHS PCI 2) are used to study the coalrock deformation damage and acoustic emission (AE) characteristics. The results show that the failure of coalrock under unloading condition exhibits strong brittleness and happens in sudden and is mostly of tensile shear failure type. The evolution curve of cumulative ring down count of acoustic emission can better reflect the coalrock unloading damage evolution process, and the whole unloading failure process can be divided into three stages: the stage of damage weakening, damage stably development stage and the stage of accelerated damage development. During the mining process the confining pressure of the coalrock is unloaded, the coalrock rapidly arrives at the third stage of the whole unloading failure process, and the damage is accumulated rapidly and the fracture failure of coalrok occurred suddenly, then follows the coalrock dynamic disaster.