堆载预压情况下基底土质对路基沉降影响的分析研究

以京沈客运专线安匠站的两段堆载预压路基工程为依托,搜集堆载预压期间的沉降监测数据,建立双曲线模型和灰色系统GM(1,1)模型,对该路基沉降进行预测分析。结果表明,该段路基沉降已达到相对稳定,基底粉质黏土较其他土质压缩模量更小,在堆载预压载荷下会产生更大的沉降量,并且达到稳定的时程较其他土质更长。

压实频次及土质对路基压实振激加速度的影响分析探究

实验路段简介;实验段基土基本特性;土质和压实频次对压实振激加速度的影响分析。本研究选取案例3个工程路段,以不同压实段压实实验成果比较分析的方式,对压实频次及土质对路基压实振激加速度的影响课题开展专题分析探究,以为同类路基压实工程应用提供研究和技术参考。

朔黄铁路路基病害整治措施

介绍朔黄铁路路基病害整治方案,重点阐述斜向旋喷桩注浆加固、挤密桩加固、基床土质改良及铺设复合防排水板等4种不同加固路基的方法。应用到既有线路基加固整治,具有快速安全高效的特点,能够在天窗时间内进行施工作业。经整治处理的路基,各项技术指标达到预期效果。

水闸底板测压管水位“异常”变化影响因素研究

水闸底板测压管水位观测值与理论值存在一定的偏差,呈现"异常"现象。调研江苏省三河闸、嶂山闸等6座水闸,基于已有水闸渗流研究成果和实测数据,对比分析影响测压管观测数据准确性以及水位变化的闸基土质、温度场、工程运行等因素,分析扬压力与水闸沉降变化的相关性。较壤土、砂土地基,黏性土基水闸测压管水位变化影响因素更为复杂,受上下游水头差、底板轮廓线、闸基土质、温度场、工程运行等综合因素影响。水闸底板测压管水位与沉降关系密切,测压管水位偏高引起的水闸底板上浮问题应引起注意,相关研究对分析水闸底板测压管水位变化规律具有参考作用。

Determination of the Thickness and Medium of Covering Soil for Land Reclamation

Land reclamation is a process of ecosystem reconstruction, for which it is very important to keep co-adaptation between plants and the below ground habitat. In order to keep the co-adaptation among plant species, thickness of covering soil and medium of covering soil to establish a self-regulating ecosystem, the thickness of covering soil of land reclamation for plants in different living forms by synusia structure of plant below-ground habitat and medium of covering soil by ecological factors of plant below-ground habitat were studied. Synusia structure of plant below-ground habitat was recognized through investigation on structure and root of plant community, and ecological factors were determined through soil profile investigation. The thickness and medium of covering soil of land reclamation for the tree, the shrub and the herb were proposed.

Advances in Soilless Culture Research

Soilless culture refers to the technique by which crops are grown using nutrient solution or solid substrate along with nutrient solution without natural soil. This technique has developed for more than 150 years, and plays an essential role in promoting the development of horticultural, agricultural and forestal production, as well as agricultural modernization. Substrate and nutrient solution formulae and their application are the core of soilless culture technique. Based on the classification system of soilless culture, the types, advantages and scope of application of substrate formulae for growing vegetables and flowers in soilless culture, as well as the types, advantages and scope of application of nutrient solution formulae, and the regulation of nutrient solution ingredients are first systematically summarized in this paper; then, the advantages and disadvantages of the inorganic energy-intensive soilless culture and eco-organic soilless culture, and their scopes of application are analyzed; finally, research directions for further perfecting soilless culture technique are presented, and the outlook for the application of soilless culture is also provided.

Mixed Substrate Soilless Cultivation Techniques for Mini Watermelon in Spring Greenhouse of Beijing Area

Watermelon, as a traditional dominant crop in Beijing, has obvious indus- trial advantages. The mixed substrate soilless cultivation techniques developed by the Beijing Agricultural Technology Extension Station for mini watermelon in spring greenhouse can effectively solve the problem of continuous cropping in facility wa- termelon, and they are conducive to green, safe and efficient development of water- melon industry for fixed nutrient solution formula, automatic water and fertilizer irri- gation, stable product quality and facilitating large-scale and standardized production.

Effects of Substrates before and after Fermenting Treatment on the Growth,Development and Cut Flower Quality of Lily

[Objective] The aim of this study was to explore the effects of substrates before and after fermenting treatment on the growth,development and cut flower quality of lily.[Method] Oriental lily cultivar ＇Siberia＇ was taken as material to study the effect of using fermentative and unfermented agricultural waste as substrates on the growth,development and cut flower quality of lily.And the physical and chemical properties of substrates before and after fermenting treatment were studied.[Result] The full decomposition of agricultural waste would greatly improve the physical and chemical properties of substrates,such as the fermentative substrates changed to stabilization,the ratio of carbon nitrogen had dropped drastically,the total porosity was increase,the ratio of gas and water was better,and the nutrition elements was increased.Moreover,it could significantly increased the plant height,stem diameter,leaf number,leaf area,leaf fresh weight and so on,as well as expanded the lily roots and significantly improved the rate of cut flower and cut flower quality.[Conclusion] This study had provided theoretically basis for the cultivation of cut lily.

A new technique of combining accretion by cyclone separator and scattertube for tailings dams

A new technique of combining accretion by cyclone separator and scattertube for tailings dams was developed according to laboratory experiment, model experiment and spot experiment technology. Three tailings dams were successfully constructed by the new technique. The results of engineering geological exploration, static and dynamic test and stability analysis on Baizhishan tailings dams prove that the new technique improves structure and stability of the dams and working conditions compared with the traditional technique. The thin layers of fine-grained soils are greatly reduced, fine tailings sand is solid to make the dam stable and seepage conditions are well improved; the immersing line of the dam descends. In addition, the stability and liquefaction resistance of tailings dams are strengthened remarkably. The interior stress is compressive stress, stress level of every element is less than 1.0 and safety coefficient of every element is greater than 1.0. The safety coefficient against liquefaction of every element of tailings dams is greater than 1.5 according to the analysis of seismic response by finite element method.

Rehabilitation of bauxite residue to support soil development and grassland establishment

Rehabilitation(amendment and vegetation establishment)on bauxite residue is viewed as a promising strategy to stabilize the surface and initiate soil development.However,such approaches are inhibited by high pH,high exchangeable sodium(ESP)and poor nutrient status.Amendment with gypsum is effective in improving residue physical and chemical properties and promoting seed establishment and growth.Application of organics(e.g.compost)can address nutrient deficiencies but supplemental fertilizer additions may be required.A series of germination bioassays were performed on residue to determine candidate species and optimum rehabilitation application rates.Subsequent field trials assessed establishment of grassland species Holcus lanatus and Trifolium pratense as well as physical and chemical properties of amended residue.Follow up monitoring over five years assessed elemental content in grassland and species dynamics.With co-application of the amendments several grassland species can grow on the residue.Over time other plant species can invade the restored area and fast growing nutrient demanding grasses are replaced.Scrub species can establish within a 5 Yr period and there is evidence of nutrient cycling.High pH,sodicity and nutrient deficiencies are the major limiting factors to establishing grassland on residue.Following restoration several plant species can grow on amended residue.

Unsaturated Creep Behaviors of Weak Intercalated Soils in Soft Rock of Badong Formation

The cutting slopes in soft rock of redbed appeared in Yichang-Badong highway often suffer from the instability along weak intercalations, so the creep behaviors of weak intercalated soils are crucially important for the stability of cutting slopes. Because the deformation of weak intercalated soils is significantly affected by water content due to the strong water sensitivity, it is necessary to study the influence of matric suction on the creep behaviors of weak intercalated soils. In order to find out the unsaturated creep characters of weak intercalated soils, a GDS unsaturated triaxial apparatus was used. Then the triaxial creep experiments on weak intercalated soil samples under varying matric suction were conducted to obtain the unsaturated creep curves. The results show that the weak intercalated soils have obvious creep behaviors, and the creep strain is in nonlinear relationship with stress and time. When the matric suction is constant, a larger deviator stress will lead to a larger creep strain; When the deviator stress is constant, a smaller matric suction will lead to a larger creep strain. Based on the Mesri creep model, an improved creep model for weak intercalated soils under varying matric suction was established, in which the relationship of stress-strain was expressed with a hyperbolic function, and the relationship of strain-time was expressed with power functions in stages. Then an unsaturated creep model including stress-matric suction-strain-time for weak intercalated soils was established based on the power function relationship between matric suction and Ed(a parameter of the improved creep model). The comparison of the calculated values of creep model and the experimental values shows that the creep behaviors of weak intercalated soils can be predicted by the unsaturated creep model by and large.

Natural ripening with subsequent additions of gypsum and organic matter is key to successful bauxite residue revegetation

The processes involved in the major steps of successful revegetation of bauxite residues are examined.The first phase is the natural physical,chemical and microbial ripening of the profile.This involves allowing the profile to drain,dry,shrink and crack to depth,leaching of soluble salts,alkalinity and Na down out of the surface layers,acidification by direct carbonation and natural seeding of tolerant vegetation with an accumulation of organic matter near the surface and an attendant development of an active microbial community.Following ripening,the surface layer can be tilled and gypsum and organic matter(e.g.manures,composts,biosolids)incorporated.These amendments result in a further decrease in pH,increase in Ca and other exchangeable cations,increased leaching of Na(with a reduction in exchangeable Na and ESP),improved physical properties,particularly aggregation,and a large increase in microbial activity.Other important considerations include the choice of suitable plant species tolerant to salinity/sodicity and local environmental conditions and the addition of balanced fertilizer applications.

Development of Organic Ecological Soilless Cultivation

This paper reviewed the development of organic ecotype soilless cultivation, the characteristics and advantages and development prospects, and the sources, types and nutritional characteristics of main cultivation. Compared with other cultivation methods, the research analyzed development prospects of soilless cultivation technology.

An improved Mesri creep model for unsaturated weak intercalated soils

The weak intercalated soils in redbed soft rocks of Badong formation have obvious creep characters. In order to predict the unsaturated creep behaviors of weak intercalated soils, an unsaturated creep model was established based on the unsaturated creep tests of weak intercalated soils by using GDS triaxial apparatus. The results show that the creep behaviors of intercalated soils are apparent and significantly affected by matric suction. Based on this, an empirical Mesri creep model for intercalated soils under varying matric suctions was built. The fitting results show that the parameters Ed and m of this model are in good power relations with matric suction s and stress level Dr, respectively. An improved Mesri creep model was established involving stress-matric suction-strain-time, which is more precise than the Mesri creep model in predicting the unsaturated creep behaviors of weak intercalated soils.

Load-settlement behaviour of a strip footing resting on iron ore tailings as a structural fill

This study presents a laboratory investigation of load-settlement behaviour of a strip footing resting on iron ore tailings used as a structural fill.The footing was placed at various depths in the tailings bed.The relative density of the tailings was varied as D_r = 50%,70%and 90%.An incremental load was applied on the footing while observing the settlement until the failure took place.The results obtained for tailings were compared with those for the sandy soil.It is observed that the load-bearing capacity and stiffness increase with an increase in footing embedment depth and relative density.Compared to load-settlement behaviour of Perth sandy soil,the tailings fill could have as high as 22 times and 13.5 times the load-bearing capacity and stiffness,respectively.Therefore,the replacement of sandy soil with iron ore tailings for structural fills is cost-effective,and moreover,this application contributes to environmental sustainability in construction.

Subsidence rules of underground layer thickness： Lu＇an Coal Base coal mines for different soil as an example, China

Damage caused by underground coal mining is a serious problem in mining areas in China; therefore, studying and obtaining the rules of ground movement and deformation under different geological conditions is of great importance. The numerical software ANSYS was used in this study to simulate mining processes under two special geological conditions： （1） thick unconsolidated soil layer and thin bedrock; （2） thin soil layer and thick bedrock. The rules for ground movement and deformation for different soil layer to bedrock ratios were obtained. On the basis of these rules, a prediction parameter modified model of the influence function was proposed, which is suitable for different values of unconsolidated soil layer thickness. The prediction results were verified using two sets of typical field data.

A new inorganic-organic hybrid material as consolidation material for Jinsha archaeological site of Chengdu

An organic-inorganic epoxy-silica-acrylate(ESA) hybrid material was used for the consolidation of Jinsha archaeological site of Chengdu in China.The hybrid materials have multiple functional groups,such as anhydride,epoxy,hydroxyl and carboxyl,which can form networks at room temperature and result in an enhanced chemical and water resistance of the consolidated soil.With increasing of TEOS content,the hybrid materials keep colorless with only some reduction of transparency,while the hybrid materials obviously turn from moderate yellowish to brown yellow with the increase of the epoxy resin(EOR) content after 120 min UV irradiation.SEM observation indicates that the hybrid soil consolidation materials can effectively penetrate into the soil substrate,fill up most of the pores,decrease the area porosity and consolidate the Jinsha archaeological soil.The consolidation performances are in the sequence:ESA > K2SiO4(PS) > tetraethyl orthosilicate(TEOS).

Seed Germination and Dormancy for Iris Chrysographes （Iridaceae） from China

Several Chinese Iris species have potential for medicinal and ornamental use, but they have poor, erratic or slow seed germination. The aims of this study was to classify Iris ehrysographes dormancy type and investigate the optimum treatment for seeds germination through examining the effects of various incubation temperatures, light conditions, scarification, stratification and soil substratum. Seed viability of/. chrysographes was 74% and seeds imbibed water very fast. No seeds germinated on stratification, soil substratum, constant or alternating temperatures, light and darkness treatments. Seeds germination of different mechanical restriction treatments had significant differences. The results indicated that： （1） removal of seed coat was the most effective treatment for/. chrysographes germination; （2） physiological dormancy phenomenon was found in this species.

Changing Wetland Environment Based on Water and Soil Quality Analysis of Selected Wetlands, Assam, India

Wetland environment of Assam is fast changing due to encroachments, dumping of solid and liquid wastes, excessive use of wetland water, over exploitation of wetland resources, overgrazing, over fishing, hunting, poaching, unscientific construction of engineering structures across and along the wetlands, unscientific land use in surrounding areas and various human interferences. On the other hand wetlands play an important role in charging ground water table, sinking of carbon, providing livelihood to thousands of people through fishing, collecting edible plants, agriculture, irrigation and commercial fisheries, besides enrich biodiversity and maintaining environmental quality of a region. The life of wetlands depends on the quantity and quality of water. Any change in water quality and quantity affect the biotic regime of the wetlands. Fish and other aquatic animals and plants found in all levels （floating, rooted, submergent and emergent etc.） are affected by the changes, which are taking place in wetland water. The present study concerns in understanding the environmental quality of the wetlands in Dimoria region of Kamrup （Metro） district, Assam based primarily on the water and soil quality of selected wetlands viz. Jiong, Parkhali, Bomani and Duani.

Effects of Different Substrate Composition on Growth of Gesneriaceae Plants

The cultivation experiment was carried out to investigate the effects of dif-ferent proportions of peat soil, perlite, vermiculite and yel ow mud on growth of Gesneriaceae species （Chirita gueilinensis, Sinningia speciosa, Lysionotus pauci-florus, Hemiboea henryi, Aeschynanthus acuminatus, Saintpaulia ionantha）. The growth traits of each plant growing in 7 different matrix materials were investigated. The plant height, crown width and chlorophyl content of each plant were mea-sured. The results showed that the best substrate ratio was peat soil∶vermiculite=2∶1 for C. gueilinensis, L. pauciflorus and H. henryi; peat soil∶perlite∶vermiculite = 2∶1∶1 for S. ionantha; peat soil∶vermiculite∶yel ow mud=2∶1∶1 for S. speciosa; peat soil∶per-lite∶vermiculite∶yel ow mud=2∶1∶1∶1 for A. acuminatus.