西南交通大学本科毕业设计
外文翻译
年级: 2005级
学号: 20050403
姓名: 段晓沛
专业: 土木工程
指导老师: 罗强教授
Several Motives to Bring the Research on Landfill Cap Covers to the Standard of the Researchers about Bottom Liners
ABSTRACT: The behavior of the cap barrier (and mainly the sealing layer) in the central area of a landfill where the slope is low, is considered. The main regulations about landfills are concentrated in the present time on the requirements related to the bottom barrier. The cap barrier has also a fundamental function (to limit or to control the humidity of the confined waste). It is shown in this Lecture, which is supported by the presentation of some experimental researches, that meeting this target is really a big challenge and also an important ecological challenge since landfills are an important spring of methane, potent greenhouse gas. First and foremost an in-depth research on the behavior of the confined waste is necessary to demonstrate the technical interest of geo synthetic solutions and also to devise new geo synthetic systems.
KEY WORDS: landfill, waste, biodegradation, greenhouse gas, settlement
INTRODUCTION
Firstly, it’s worth noting that landfills should be considered as a modern technique of treatment of waste, which was moving and developing significantly during the last decade. The main regulations about landfills are concentrated in the present time on the requirements related to the bottom barrier. The cap barrier has also a fundamental function (to limit or to control the humidity of the confined waste). To cover with an efficient cap barrier a waste disposal is a key issue.
In a previous Keynote Lecture (Gourc, 2004), the global problem of stability of geosynthetics composite systems used as cap barriers on steep slopes of landfills were considered (Gourc et al, 2008).
In the present Lecture, the behavior of the cap (and mainly the sealing liner) in the central area of a landfill is considered. It is demonstrated that an in-depth knowledge of the waste behavior is required before to optimize the concept of the liner. Geo synthetics solutions are very often better than mineral layers; in many cases
these geo synthetics solutions have already proved their worth, but new applications are still possible. The application of geo synthetics to cap over of new landfills but also of old uncontrolled dumps is a promising market.
CAP COVER REQIREMENTS
The French regulation does not completely specify the structure of the cap cover (Decree Sept. 1997) and recommend only two concepts according to the nature of waste (Fig. 1):
-for Municipal Solid Waste (MSW) , with a biodegradable part, the cover must be provided “with a semi-permeable layer in natural fine soil compacted on a thickness of at least 1 meter, or any equivalent device ensuring the same effectiveness.”
-for Hazardous waste, it must be provided “with an impermeable layer of 1 meter characterized by an hydraulic conductivity lower than 1.10-9m/s associated at a geomembrane or any equivalent device.”
Indeed this regulation does not meet the many concerns related to the behavior of a landfill cap cover under complex solicitations.
STORAGE OF HAZARDOUS WASTE
Landfill for this type of waste includes generally, following regulations in many countries, a cap cover with a compacted clay liner (CCL). Imperviousness of clay is essential to safeguard the hazardous wastes against wetting, in order to prevent leaching and washing of the waste and consequently possible pollution of the ground water in case of filing of the bottom barrier. However the CCL meets many problems, in particular those related to its mechanical solicitations after closing the cell, specifically differential settlements.
Some experiences carried out in France which demonstrate the sensitivity of CCL to cracking in case of bending solicitation are presented:
Behavior of a clay layer subjected to a sinkhole situation.
Test procedure
The experiments were performed on the CERED site (Suez) (Fig.2) on clay material with a large proportion of coarse soil (material conventionally used in France
for waste landfill sites).
The CCL (Aupicon et al, 2002) is compacted on a cavity of (2m×2m) filled with expanded clay beads. In a second stage, the clay beads are removed, simulating a concentrated subsidence of the waste. This condition is specifically severe but may correspond to realistic situation for instance in case of internal collapsing or burning of a piece of waste.
Two conditions were considered:
-The first one was a layer of unreinforced clay, thickness H reduced to 0.6 m, above a sinkhole with a span of a length L of 2 meters.
- The second one was a layer of the same clay, thickness H reduced to 0.6 m, reinforced at the base by a geosynthetic sheet, (Fig.2). The tensile stiffness of the synthetic sheet (overall length of 8 m) is J=1818 kN/m. The anchorage of the sheet (free ends) is obtained by friction (no sliding observed at the edges).
The vertical deflection (f) is recorded at every stage of the experience.
Layer of reinforced clay
During the first step (the process of emptying of the cavity), a detaching is observed between the lower and upper sub-layers of clay, revealing cracks inclined towards the edges of the cavity (Fig.2 and 3) corresponding to the compaction in two stages. The poor interlocking between two compacted layers is a classical fault and it was finally interesting even if it was unintentional. Consequently the lower sub-layer behaved independently like a 0.3 m layer subjected to bending under its own weight. The geotextile followed the deformation of the lower sub-layer but was not very sollicitated: the maximum vertical displacement of the lower sub-layer being still small (f = 10mm). The upper sub-layer did not deform significantly under its own weight and it could be considered that water and gas tightness were kept satisfactory for this layer.
In a second step, an overload was put at the surface in order to increase the bending deformation of the structure (Fig. 4). Finally as it was impossible to obtain a short term collapse of the structure, the long term deflection was monitored under a constant overload (q) for several months. An increase in vertical deflection (creep+
anchorage slip) of the clay and geo synthetic liner was observed. The evolution of the vertical deflection during the complete experience versus the total vertical load applied to the geotextile (Q=own weight of the clay layer + overload q) is plotted on the (Fig.5)。
Layer of unreinforced clay
The initial observation made on the front of the unreinforced earthwork revealed a network of cracks similar to that observed in the reinforced earthwork. The horizontal crack due to interlayer detachment split the earthwork into two sub-layers about 0.3 and 0.7 m thick.
While emptying the expanded clay beads we could observe the gradual subsidence of blocks of the lower sub-layer by 0.3 m which finally after a first overloading was dropping in the cavity.
The evolution of the deflection versus the load (Q) and the elapsed time is plotted on the Fig.7. Due to the detachment of the lower sub-layer, only the deflection at the bottom of the upper sub-layer can be monitor ed. It’s worth noting that, at the intermediate stage of unloading on the figure 6, several cracks initiate in the upper sub-layer.
This preliminary experience, although sereve and schematic, demonstrates:
-the poor ductility of clay material, even if compacted at a water content far higher than the W opt
-the efficiency of geosynthetic to stop a dramatic collapsing if the clay barrier, but not sufficient to prevent its cracking even if the stiffness of the selected geosynthetic can be considered in the high range.
Behavior of cap cover for nuclear waste of low activity
The safe storage of nuclear waste is a big issue. For nuclear waste of low activity, it’s considered as acceptable to select a surface storage, on the condition that the
integrity of the cap over could be guaranteed until 300 years. The radioactive material is packaged in parcels of different shapes and generally of a unit volume higher than several m3. The space between the par cels is filled with sand. It’s important to maintain the waste in a dry condition to avoid a leaching process.
Two landfill of this type are existing in France, La Hague which was closed in 1991 and Soulaines which was open in 2006 and the experience related to the cap cover for these two sites is related here.
La Hague landfill 17 years old
The specific shape of the cover was selected in order to obtain an efficient collection of run-off water. The complete can system consist, from the bottom to the top, of a coarse aggregate layer (0.6m thick), a sand layer (0.2m), a bituminous geomembrane, a sand drain (0.3m), a biological barrier of coarse aggregate(1m) and a topsoil(0.2m)(Fig.8). The geomembrane has a mass per unit area (6㎏/㎡), a tensile strength of 20kN/m for an elongation(40%). The seams are made on site by welding with an overlap of 0.20m.
After 17years, global behavior of the barrier is correct except mainly in one part where a differential settlement was observed.
Soulaines new landfill:
The structure of the cap barrier is following the specific regulation for hazardous waste which includes a clay layer of 1 meter thick above a geomembrane(Fig.9) Waste is stored in blocks of variable shape, in the form on big bags, tanks and barrels and spaces between blocks are filled with sand. Due to this type of storage and prevalence of voids which, settlements within waste are likely to occur as in the previous case . The characteristics of the clay are presented in the table 1: Field test procedure for the Soulaines experience
The influence of differential settlements within the waste mass on the cap cover can be modelled by submitting a clay layer to bending stress(Jessberger and Stone, 1991; Viswanadham and Sengupta, 2005). In the framework of the present paper only
bursting tests which induce the most critical situation with regard to the risk of cracking are presented (Fig.10). Indeed the stretched zone in this test is located at the top of the layer and consequently not confined. These tests can be considered as inverted bending tests. They don’t represent the actual situation in case of differential settlements but these tests present the additional benefit of allowing observation of initiation of cracking along the tensile fibre of the liner (Camp et al. 2007).
In the second phase of this on-going research programme, it will be proposed a test of differential settlements (vertical displacement of the plate in the downward direction) to the overall structure of the cap cover, including the geomembrane and the reinforcement geotextile layer. To simulate the confinement of the clay layer in the cover barrier, an overburden corresponding to the actual protecting layers in the cover system will be imposed on the surface of the clay.
For the implementation of these tests, a rigid pit made of reinforced concrete (width: 2m) was built, and an articulated steel plate (2m×2m) placed over the pit. Plane strain state is considered as existing for a central profile. A system of four vertical hydraulic jacks fitted in the pit allows the plane to induce vertical movement of the central plate. These jacks are synchronized in such a way that they impose a vertical translation of the central plate. A vertical maximum movement of 250 mm is possible.
Three large scale tests were performed. For tests T1 and T2, a moulding water content equal to 19％(which is W opn +2％) and a moulding water content of 20.5﹪was maintained for test T3 (which is W opn +3.5％).
Field tests have confirmed that clay is very sensitive to flexural tensile stresses. In all tests, cracks were observed to appear along the surface of the clay symmetrically for vertical movement as small as 30mm. Based on the analysis of photos (Fig.11) allow to determine the strain at initiation of crack of the clay along the bottom fiber of the clay. The value of? is 0.6 ％for the test T3 (W opn + 2％). A slight delay in observing strain at crack initiation can be noted for the clay layer compacted towards wet side of its optimum water content. These result confirm the observations made in the laboratory through bending tests on small beams made out
of same soil. Strain at initiation of cracks is found to be in the range of 0.04％- 0.4％, depending upon the moulding water content. Earlier Edelmann etal. 1996 have reported that settlement test on clay and silty soils were observed to give strain at crack initiation equal to 0.2 to 0.3％.
A clear difference was observed between on one hand the tests T1 and T2 and on the other hand the tests T3. For tests T1 and T2, two main cracks were observed along the width and depth of the clay layer (Fig.11 and 12). The clay layer was found to experience cracking almost its entire depth. Whereas for the clay having moulding water content on the wet side of optimum (i.e. W opn+ 3.5％), a single crack of 410mm deep was observed to take place centrally and the bottom portion of the clay layer was kept intact. This result is consistent with previous results about the influence of water content on the flexibility and the tensile strength of the clay. With an increase in water content above the optimum Proctor, a slight delay in the initiation of cracking is expected.
Centrifuge tests
A geotechnical centrifuge can be used to perform tests on models that represent full-scale prototypes under normal field conditions. A 1／N scale model tested at a centrifugal acceleration N times the earth’s gravity(g) experiences stress conditions identical to those in the prototype. The 4.5m radius large beam centrifuge at Indian Institute of Technology Bombay (IIT Bombay), India was used in the present study. Centrifuge busting tests were performed with an acceleration 12.5g.
Several tests were performed by Viswanadham and Manesh(2002). The main results corresponding to the test C1(W opt+ 2％) are presented below. The good agreement with the observations on the large scale experimentation (front view on Fig.13 and Fig.14, top view on Fig.15) demonstrates the relevance of the centrifuge facility.
So it could be justify to use centrifuge tests for complementary testes which were not performed before at the real scale.
(Viswanadham et al,2005) demonstrated the interest of a reinforcement of clay by short fibers. A new research in collaboration with LTHE laboratory in Grenoble is
in progress to test for application above the micro-reinforcement and also the reinforcement by a geosynthetic layer included in the granular layer.
STORAGE OF (BIOEGRADABLE) NON HAZARDOUS WASTE
It's possible to distinguish three waste management scenario (Cossu et Piovesan,2007), recycling and mechanical-biological treatment, thermal treatment(incineration) and landfilling(Fig.16). The zero Waste option relies on recycling alone(0% landfilling and 0% incineration) should be regarded as a desirable but far perspective.
Landfill engineering varies dramatically from one to other country, both in term of conceptual design and technology. This has led to an integrated management procedure, with recovery of energy and influence on global climatic change. The bioreactor technique which is promoted specifically in France should be considered in the context.
Semi-permeable or impermeable cap barrier?
As far as the cap barrier of non-hazardous waste is considered, its design is finally more complex than for hazardous waste. In this former case, only sealing function of the barrier was expected in order to avoid wetting and leaching of the hazardous waste. In case of biodegradable waste, the degradation in anaerobic conditions generates mainly CH4 (60%) and CO2 (40%) in the presence of water. Therefore the concept of "dry tomb" is not relevant since the biodegradation is postponed, and this is inconsistent with the principle of sustainable. Consequently the regulation suggest a “semi-permeable” barrier corresponding to a silt layer of hydraulic conductivity(10-7 m/s) but wetting of waste will be strongly dependant of the climatic conditions. It appears more interesting to associated a sealing layer of low hydraulic conductivity to a system of injection of water at a controlled rate. This is the Bioreactor concept which accelerates the degradation of a domestic waste as can testify the flow of CH4 comparing with the case of a conventional landfill (Fig.17) The second advantage of an impermeable cap barrier if the improved collection of biogas which are greenhouse gas (Staub and Gourc,2008):
A biodegradable landfill generates emissions of CO2 and CH4, both are
greenhouse gas but their global warning potential (GWP) differs greatly since the ratio for T=100 years is:GWP(CH4) / GWP(CO2)=25 , the methane is far more potent. This factor (25) is used for converting the volumes of carbone dioxide is worldwide the second greenhouse gas. Consequently it’s very important to collect the methane. On the (Fig.18) it’s shown that in France landfills contribute for 16% to the methane emissions.
The Fig.19 demonstrates that for a landfill the gas tightness of the cap barrier is the key factor to improve the contribution to sustainable development by mitigation of the emissions. The Bioreactive Landfill is supposed to have an efficient sealing layer. In this case its performance is better than the one of an Incinerator. Therefore it’s of the highest importance to cover a landfill of biodegradable waste with an efficient barrier. However this is a challenge difficult to take up , due to the complex behaviour of the underlying waste body and the design of the cap cover requires to study in depth the mechanics of waste.
Mechanical behaviour of the underlying waste
Waste is a very compressible material which, when lifted in high embankments, induces major technical constraints as well as economic concerns. Settlements represent in fact a serious threat to the integrity and the performance of the cap cover and the associated structures of the landfill. A laboratory prototype cell （m3）was developed allowing an in-depth settlement analysis for a waste material subject to various conditions of compression and leachate recirculation (Fig.20). The flexibility of laboratory cell makes possible a parametric study that is not practicable on-site. In particular, interesting correlations can be made between the mechanical behavior of the waste and its hydro-physical characteristics (Olivier and Gourc, 2007) On the Fig.21 a typical diagramme corresponding to the situation of a sample of waste embedded in a landfill is presented ( Gourc and Olivier 2006). The municipal solid waste(MSW) sample is firstly subjected to an increasing overload( until 130 KPa after week) which induces a primary settlement of 25.4%。During the following 22 months,the surcharge is remaining constant and the additive secondary settlement
is 24﹪.
It worth noting the huge value of the compressibility of waste , since a settlement of 24﹪results in a vertical translation of 7.2m for a cap barrier covering a column of waste 30m high, which is a classic value. On the other hand, the diagramme of the Fig.21 emphasizes the significative influence of a humidification of organic waste by leachate in order to accelerate settlements, that is to say the biodegradation of waste.
将有关垃圾填埋场封顶的研究应用到有关底部衬板研究标准的几个动因
摘要：考虑的是填埋场在有较低坡度时，其中部区域的顶部阻隔（大多是密封层）的性能。目前，填埋场的主要规定集中在与底部阻隔有关的要求上。顶部隔离也有一个基本的功能（限制或控制受限垃圾的湿度）。这个由实验研究的所支持的讲座展现给我们的是，达到这个目标确实是一个大挑战，同时自从垃圾填埋场成为沼气和有效的温室气体的重要来源后，达到这个目标也是重要的生态学挑战。首先并且是最重要的，一个有关受限垃圾的性能的深入研究对于激发土工材料的合成解决方案的技术兴趣以及设计新的系统是必要的。
关键词：垃圾填埋场，垃圾，生物降解，温室气体，沉降
引言
首先，垃圾填埋场应该被认为是一种垃圾处理的现代技术，这是很值得注意的，这种技术在最近十年有了很大的发展。目前，填埋场的主要规定集中在与底部阻隔有关的要求上。顶部阻隔也有一个基本的功能（限制或控制受限垃圾的湿度）。用一个有效的顶部阻隔来覆盖处理垃圾是关键问题。
在之前的主题演讲(Gourc, 2004)上，土工合成材料黏土垫被用来解决垃圾填埋场的较陡坡度上的封顶的的稳定性，这一全球性问题被考虑。(Gourc et al, 2008).
在这个讲座中，考虑的是在填埋场的中部区域的顶部阻隔（大多是密封垫）的性能。它展示出在优化衬垫构思之前，对垃圾性能的深度了解是必要的。土工合成材料的解决方案通常比矿物层好；在许多情况下，这些土工合成材料的解决方案已经证明了它们的价值，但是新的应用仍是可能的。对于新垃圾填埋场的顶部隔离以及旧的无控制堆放的应用是一个有发展潜力的市场。
封顶要求
法国规定并不完全明确说明封顶的结构(Decree Sept.1997),建议根据垃圾的性质把其分成两大类（图1）：
—对于城市固体垃圾,用一个可生物降解的部分,必须提供“具有可将存在于天然优良土中的弱透水层压缩至少1米厚度的压力,或任何等效装置,保证同一效力。”的覆盖。
—对于有害废物，必须为它提供“一个1米的不渗层，这个不渗层以低于1.10ˉ9米/秒的水力传导系数为特征，结合一个土工膜或任何一等效装置。”
确实，本规定不符合在复杂条件下与填埋场封顶的性能有关的许多问题。
有害垃圾的储存
一般地，在许多国家的规定下，这种类型的垃圾填埋场包括带有压实粘土衬里的封顶。在一旦底部隔离层被破坏的情况下，在防止垃圾被浸洗而导致的可能的地下水污染方面，压实粘土衬里的不透水性对于防止有害垃圾不受湿是至关重要的。但是压实粘土衬里遇到很多问题，特别是涉及到覆盖了一个填埋场后的力学变形的问题，尤其是出现沉降差异。法国的一些经验，表明了压实粘土衬里一旦达到受弯极限出现裂缝的敏感性：
排水条件对粘土层性质的影响
测试程序
实验在CERED场地运行（Suec）(图2)，用含有较大比例粗粒土的粘土为材
料（这种粘土在法国通常被垃圾填埋场采用）。
压实粘土衬里(Aupicon et al, 2002)，在一个充满膨胀粘土粒的2m×2m 的容器中被夯实。在第二阶段，粘土粒被移开，模拟一个垃圾的集中沉降。这种模拟情况是特别粗糙,但可能与现实情况相符合，比如垃圾体出现内部坍塌或者自燃情况下。
两种情况被考虑到：
1）第一种情况是无筋粘土层，厚度H为1m,在排水口以上有2m宽的跨度L。
2）第二种是同样的粘土层，厚度H减少到0.6米，在底部用一个土工膜片加固，（图2）。土工膜片的抗拉强度（总长度8米）是J=1818 kN/m。膜片的（自由端）锚固力通过摩擦而获得（没有在边缘观察到滑动）。
竖向挠度(f)在实验的每个阶段都有记录。
加固粘土层
在第一步(空洞的排空过程), 观察到在粘土替代层上部和下部下之间出现脱离,表明相对应于两个阶段的压实情况裂纹有向腔的边缘延伸的趋势 (图2和3)。在夯实的土层之间的较弱的联接是一个经典的过错，即使它是无意的，最终也会很有趣。因此较低级的替代层能独立地实施功能，像在自身重量下下弯的0.3米厚的层。土建纺物跟着替代层下部的变形一起变形，但是并不是紧连在一起的：替代层的下部最大竖直位移依然很小（f=10毫米）。层下上部分在它自身重量下没有显著变化，而且它可以被认为是水和气密性保持得很好。
在第二步，为了增加结构的弯曲变形，超荷被施加在粘土层表面（图4）。最后，尽管促使一个结构倒塌是不可能的，在不变的超荷持续作用几个月情况下，被监测到粘土层出现长期变形。粘土和土工合成衬垫垂直偏向（徐变和锚固变形）的增加被监测到。在与总垂直负荷（粘土层自重和超载作用下土建纺物竖向变形特征曲线如图5。
无加固粘土层
在无筋土建工程前期中，最初的观察到散布广泛的裂缝，与有筋土建工程观察结果类似。水平裂缝的出现是由于夹层的剥离将土建工程分裂成两个约0.3至0.7米厚的较低的子层。
当排空膨润土颗粒,我们可以观察在第一次施加超载之后，替代层的下部石块最终会沉降0.3m.
变形和负荷(Q)和消耗时间的特性曲线如图7。由替代层下半部分的分离,只能够监测到替代层上半部分的底部的挠度。值得一提的是,在图6卸载的中间阶段的,裂缝首先出现在替代层的上半部分中。
这个初步的体验,虽然粗糙,但是证实了：
—黏土材料的可延性很差,即使在含水量远远高于Wopt的条件下被压实。
—土工合成材料可以有效地阻止粘土封顶的突然倒塌,但是不能足够防止其开裂,即使选择的土工合成材料的刚度范围很大。
低活性核废料的封顶性能
安全储存核废料是个大问题。对于低活性核废料,如果能够保证封顶300年后还完好无损，考虑选择地面储存是可以接受的。放射性物质被包裹在不同形状的盒子里，一般地，这些盒子的的单位体积要大于几个平方米。盒子里的空间填满沙子。为了避免泄漏，保持盒子的干燥是重要的。
属于这些类型的填埋场，有两个现存在法国,海牙的在1991年被关闭，Soulaines 2006年被打开，与这两个垃圾场封顶的相关经验,在这里被涉及到。
存在17年的海牙填埋场
选择特殊形状的封顶覆盖是为了有效地收集地表水。完整的系统组成,从下往上,一层厚粗骨料(0.6m厚)，一层砂土层(0.2m)，一层沥青土工膜，砂性排水沟(0.3m)，一层由粗骨料(1m)和表层土组成的(0.2m) 生物屏障(图8)。单位面积有大量的土工膜 (6kg/㎡)，土工膜的拉伸强度为20kN / m，延伸率(40%)。在现场制作时，接合处通过0.20m的焊缝联接.
十七年之后,此封顶的性能都表现的很好，除在某些部分发生了不均匀沉降。
Soulaines新垃圾填埋场
这个封顶的结构是按照填存危险废物的具体规定设计的，包括位于土工膜之上的1米厚粘土层(如图9)。
废物贮存在不同形状的模子里,比如较大的袋子，容器或者桶等，空间之间都堆满沙子。由于这种类型的存储和空隙的流动,废料内的沉降有可能会发生。粘土的性质列在表格1中：
表1 Soulaines填埋场粘土层特性
Soulaines垃圾填场
Soulaines现场测试程序
在大型垃圾填埋场顶部覆盖层产生差异沉降的影响,可以通过使粘土层产生弯曲应力模拟得到(1991年Jessberger和2005年Viswanadham Sengupta)。在目前的文献体系里,只有诱发最紧急情况的爆破试验与出现爆裂的危险有关(图10)。事实上在此测试中，伸展带位于层的顶部,因此并没有被限制。这些测试可以被视为反弯曲试验。一旦出现差异沉降，他们不代表实际情况,但在测试中，额外地观察到沿拉伸纤维的衬垫会出现早期裂纹 (camp et al.2007年)。
在第二阶段的研究计划,提出了一个测试封顶的整体结构的差异沉降（板的向下竖向位移）的方法，封顶的整体结构包括土工膜和加筋土纺物层。为了模仿顶部阻隔粘土层的限制作用, 在覆盖系统中，与实际保护层相应的负荷将要施加在层表面上。
为了这些试验的实施,建立了一个工程中钢筋混凝土刚性坑(宽度:200),并把一个铰接钢板(2×2)覆盖在坑之上。由于只存在一个中心侧面可以认为坑处于平面应变状态。一个安装在坑内的四个垂直液压千斤顶系统允许平面引起中央板的垂直移动。这些液压千斤顶作用是同步的,这样他们能够强加中心板一个垂直变化。一个最大为250毫米的垂直位移是可能的。
三个大规模实验被实施。测试1和测试2中，模制含水率等于19﹪（W
+2
opn
+3.5﹪）.
﹪）,在测试3中，模制含水率等于20.5﹪（W
opn
现场测试证明粘土对弯拉应力很敏感。在所有的测试中，沿粘土表面，与垂直变形相对称，观察到细如30毫米的裂缝。根据图片分析（图11），允许来确定应变的粘土的裂缝沿底部的纤维。轻微的延迟在观察裂纹应变能指出,对湿粘土层致密的最佳含水率。在实验室通过观测由同样的土粒构成的小梁的弯曲试验证实了观测结果。根据模制含水率，发现在出现裂缝早期拉应变在0.04%-0.4%范围内。Edelman1996年早些时候曾报道,在粘土、粉土沉降试验中观察到在裂纹出现早期拉应变等于0.2到0.3%。
一个明显的差别一方面出现在测试T1和T2之间,另一方面出现在测试T1,T2和测试T3之间。在T1和T2中, 观察到进行了沿粘土层的深度和广度方向出现了两条主裂缝（图.11和图.12)。在整个深度方向粘土层被发现几乎全部
+ 3.5%),一个单一的有410mm 出现开裂。而对有最佳湿度的塑限粘性土(如下W
opn
深的裂缝在中间被观察到，粘土层底部部分则保持完好。这个结果与已有的结果
编号（学号）：04054018 （2004届本科毕业生） 毕业论文（设计） ——之外文翻译 题目：非饱和水分运动参数 空间变异的研究 学院：水利学院 专业：农业水利工程 姓名：房军 指导教师：陈晓飞教授 教研室主任：孙仕军 院长：王铁良 完成日期：2004年 3 月22日
非饱和水分运动参数空间变异的研究 黄 冠 华 (中国农业大学 水利与土木工程学院, 北京 100083) 摘 要:田块尺度土壤特性的空间变异性对水分与溶质运移具有明显的影响。该研究在野外30m ×30m 面积、土壤类型为砂壤土的田块的100个空间点上,分别利用张力计和取土样室内测定的方法测定了30cm 土层深处土壤水张力、土壤容重ρ、饱和含水率s θ,与初始含水率i θ,同时利用圭尔夫仪,测定了该田块同样深度108个空间点上的饱和水力传导度s k 与孔隙大小分布参数α。利用经典统计分析与地质统计分析方法分析上述参数的空间变异特征,研究结果表明:ρ, i θ,s θ,s k 和容水度C 遵从正态分布,而α具有对数正态分布;s k ,α和C 具有较大的空间变异性,而ρ和s θ的空间变异性则较小;s k 和log α是空间统计相关的;土壤水张力的空间变异具有时不变特征,且土壤水张力方差是其均值的二次函数。 关键词:非饱和流;土壤特性;土壤水张力;空间变异 1.介绍 很显然水和溶质在自然界土壤内运输的过程由于土壤非均匀性或者空间变化性而导致了其不确定性。 在最近二十年内，水和溶质在非均质土壤中运输被描述成与土壤特性有关的随机模型为参数的随机空间函数[]51-。不过根据参考文献[]75-，给定的土壤特性的空间变化性是随现场具体情况并且随土壤的类型和研究地区的规模而变化。 即不同的土壤特性表现不同的空间变化性。 因此， 在一个具体的站点，从一个区域土壤特性的数据集合分析而获得的统计特性和空间结构， 可能不适于描述在其它场所相同的土壤特性的空间变化性。 所以，在所有研究区域内进行区域实验并且分析收集的数据集合去确定土壤空间变化性是必要的。 在这项研究过程中，从一个区域实验来处理评价土壤特性和毛细张力水头的空间变化[]9,8。用古典统计和地质统计的方法分析从区域实验收集的数据集合，并把结果与同类出版物相比较，于是得出结论。
机械设计 摘要：机器是由机械装置和其它组件组成的。它是一种用来转换或传递能量的装置，例如：发动机、涡轮机、车辆、起重机、印刷机、洗衣机、照相机和摄影机等。许多原则和设计方法不但适用于机器的设计，也适用于非机器的设计。术语中的“机械装置设计”的含义要比“机械设计”的含义更为广泛一些，机械装置设计包括机械设计。在分析运动及设计结构时，要把产品外型以及以后的保养也要考虑在机械设计中。在机械工程领域中，以及其它工程领域中，所有这些都需要机械设备，比如：开关、凸轮、阀门、船舶以及搅拌机等。 关键词：设计流程设计规则机械设计 设计流程 设计开始之前就要想到机器的实际性，现存的机器需要在耐用性、效率、重量、速度，或者成本上得到改善。新的机器必需具有以前机器所能执行的功能。 在设计的初始阶段，应该允许设计人员充分发挥创造性，不要受到任何约束。即使产生了许多不切实际的想法，也会在设计的早期，即在绘制图纸之前被改正掉。只有这样，才不致于阻断创新的思路。通常,还要提出几套设计方案，然后加以比较。很有可能在这个计划最后决定中,使用了某些不在计划之内的一些设想。 一般的当外型特点和组件部分的尺寸特点分析得透彻时，就可以全面的设计和分析。接着还要客观的分析机器性能的优越性，以及它的安全、重量、耐用性，并且竞争力的成本也要考虑在分析结果之内。每一个至关重要的部分要优化它的比例和尺寸，同时也要保持与其它组成部分相协调。 也要选择原材料和处理原材料的方法。通过力学原理来分析和实现这些重要的特性，如那些静态反应的能量和摩擦力的最佳利用，像动力惯性、加速动力和能量；包括弹性材料的强度、应力和刚度等材料的物理特性，以及流体润滑和驱动器的流体力学。设计的过程是重复和合作的过程，无论是正式或非正式的进行，对设计者来说每个阶段都很重要。 最后，以图样为设计的标准，并建立将来的模型。如果它的测试是符合事先要
农业产业化外文翻译文献(文档含中英文对照即英文原文和中文翻译)
农业产业化：从农场到交易市场 Mark R. Edwards and Clifford. J. Shultz 摘要 农业产业化就是农业以市场需求为导向，有效的满足客户以及市场要求的一系列的链条。这种变革需要一个更广泛的概念化和更准确的定义，传达一个致力于创造价值和可持续利用食物，纤维，可再生资源的更有活力，系统性，综合性和纪律性的系统。我们讨论的力量，推动这一转移到市场，提供了新的和更具有代表性农业产业化的定义，提供模型以说明一些最引人注目的趋势，并阐明这些模型关键因素和影响。 关键词：农业产业化的定义，概念模型，市场为中心，市场体系
1 绪论 农业产业化在1955年开始作为一个独特的研究领域，当时约翰.戴维斯将它定义为：农业产业化是以农场生产为中心，然后商品化。这个定义当时是最适当的，那是农业行动的重点是最大限度地生产食物和纤维。戴维斯和高德博格用新鲜的见解，将农业产业化定义为:制造和分销农场用品：在该农场生产经营、储存、加工、分销所有的农产品的商品和物品所涉及的所有业务的总和。类似的定义也有其他的人提出，如唐尼和埃里克森：农业产业化，包括所有这些业务和管理活动由公司提供投入到农业部门，生产农产品，运输，金融，处理农产品的全部过程。 这些传统的定义，随着时间的推移，对农场或生产的单位所反映农业产业化的焦点，如农业交易中心已数十年之久。今天，一个就业散点图显示，虽然超过百分之三十的就业机会农业产业化提供的，少于百分之一的人直接参与农场生产。农业产业化已不再是以农场为中心。二十一世纪农业产业化包含了更广泛的一系列行动，主要是外围行动，包括以市场为导向的可持续利用食物，纤维，和可再生资源。
毕业论文选题大全 ——WORD文档，下载后可编辑修改—— 某总承包工程合同管理案例分析浅谈建设工程招投标最低价中标法工程项目风险管理问题探究我国公路工程招投标的现状与模式工程合同管理存在的主要问题及应对措施浅谈混凝土施工中的问题及处理方法浅谈施工企业如何做好项目管理东城安全供水 政法大学博士学位论文题目参考《老子》法理念探微黑格尔论中国政制、法律及其精神缺陷清代贵州苗疆的法律控制与地域秩序缘坐研究以唐代立法、司法为背景结社：在宪法与政治之间人权视野中的罪刑法定原则没收财产刑研究犯罪被害人国家补偿制度基本问题研究论刑法的合理 古代文学论文选题古诗歌鉴赏论文：提高古诗歌阅读欣赏能力论柳永艳词及女性形象塑造庄子散文与《红楼梦》《诗经》与周代社会生活《诗经》十五国风地域考略论《水浒传》中的忠义观研究浅论诗词格韵古诗词翻译巧妙用韵的问题贾宝玉的爱情与婚姻悲剧的意义浅 简述社科毕业论文选题参考在高校人文、社科专业开设环境教育课程的实践和探讨高校社科成果评价对高校社科发展的影响研究医学院校人文社科教育的现状及比较研究陕西高校社科期刊发展问题及研究地方高校人文社科成果评价研究复杂性科学视域中的人文社科课程之构建公 教育专业毕业论文选题毕业论文是结束大学学习生活走向社会的一个中介和桥梁，下文为大家介绍教育专业毕业论文选题，让我们一起
来看看具体内容吧!在小学(某某)学科课堂教学中调动学生积极性的方法(或策略)研究素质教育背景下的小学教师专业素质研究课堂教学过程 质量工程毕业论文选题选题最好能建立在平日比较注意探索的问题的基础上，写论文主要是反映学生对问题的思考，详细内容请看下文质量工程毕业论文选题。钢板材包装木托架的承载研究和结构优化采用预制rc构件加固的砌体结构抗震性能研究西藏抗震设防单层民居试验 课程论文参考题目参考1、宗教思想与旅游文化的构建2、初探旅游地中心文化递减规律的伦理3、旅游客源地与目的地的文化交流与互动研究4、浅谈当代中国旅游文化播传播5、导游与民俗旅游文化的传播6、中西方旅游文化思想的对比研究7、论旅游产业与旅游可持续发展8 简述物理学毕业论文题目高中物理教学中学生探究能力的培养xh_2分子激发态性质的从头算研究用广义线性量子变换理论求解一类含时量子问题高中物理概念教学中抽象思维能力培养研究技校物理教学中开展研究性学习的探索与实践基于有意义分割理论的三维模型检索算法研 最新法律毕业论文设计选题001中国司法改革问题002中国法治建设问题003法律与社会问题004法律职业问题005中国法学问题006西方法律发展运动研究007发展权及发展权理论008革命与法律发展009法国律师职业组织及其自由主义思想的产生010美国律师协会与
运作整合 供应链协作的首要问题是提高运作整合的程度。供应链协作课达到的好处，直接关系到捕捉效率之间的职能的企业，以及全国的企业，构成了国内或国际供应链。本章重点阐述的挑战，一体化管理，由研究为什么一体化创造价值，并通过详列的挑战，双方的企业集成和供应链整合。必不可少的供应链流程是确定的。注意的是，然后向信息技术提供，以方便集成化供应链规划。本章最后审查了定价。在最后的分析，定价的做法和政府是至关重要的供应链的连续性。 为什么整合创造价值 基本的优点与挑战的综合管理介绍了在第1章。进一步解释整合管理的重要性，有用的指出客户都至少有三个角度的价值。 传统的角度来看，价值是经济价值。第二个价值的角度来看，是市场价值。 实现双方经济和市场价值是很重要的客户。然而，越来越多的企业认识到商业上的成功也取决于第三个角度来看，价值，被称为关联性。 物流一体化目标 为实现物流一体化的供应链背景下，6个业务目标必须同时取得：（ 1 ）响应，（ 2 ）差额减少，（ 3 ）库存减少，（ 4 ）托运巩固，（ 5 ）质量，（ 6 ）生命周期支持。的相对重要性，每个直接关系到公司的物流战略。 响应 一公司的工作能力，以满足客户的要求，及时被称为反应。作为一再指出，信息技术是促进反应为基础的战略，允许业务的承诺被推迟到最后可能时间，其次是加速投放。实施对应策略服务，以减少库存承诺或部署在预期客户的需求。响应服务转向业务重点从预测未来的需求，以容纳顾客对快速订单到出货的基础上。理想的情况是，在一个负责任的系统中，库存是没有部署，直到客户承诺。支持这样的承诺，公司必须有物流的属性，库存的可用性和及时交付，一旦客户订单收到。 差异减少 所有经营领域的物流系统很容易受到差额。方差结果从未能履行任何预期的层面后勤业务不如预期。举例来说，毫不拖延地在客户订单处理，意想不到的干扰，以便选择，抵港货物损坏，在客户的位置，和/或未能提供在适当的位置上的时间，所有创造无计划的差异，在订单到交货周期。一个共同的解决办法，以保障对不利的差异是使用库存安全库存，以缓冲行动。这亦是共同使用的首选运输，以克服意想不到的差异延误交货计划。这种做法，鉴于其相关的成本高，可以尽量减少使用资讯科技，以维持积极的物流控制。向程度的差异是最小化，物流的生产力将提高。因此，差异减少，消除系统中断，是一个基本的目标，综合物流管理。 库存减少 要达到的目标，库存减少，一个综合物流系统必须控制资产的承诺，并把速度。资产的承诺，是财政的价值部署清单。把速度，反映了利率，这是充实库存随着时间的推移。高转率，再加上预期的库存供货，平均资产用于库存正在迅速而有效利用，这就是整体资产承诺支持一个综合运作减至最低。 库存能够而且确实方便可取的好处这是很重要的要请记住。库存是至关重要的实现规模经济，在制造业和采购。目的是要减少和管理存货，以尽可能最低的水平，同时实现整体供应链绩效的目标。
外文翻译 原文 Title:Agricultural Industrialization Organization of Marketing Strategy Analysis Material source:2010 International Conference on Industry Engineering and Management Author:Zhao Yanhong, Ren Aihua Abstraet:Agricultural industrialization is the development direction of world agriculture, it is also the main form of the agricultural operation in developed countries. Vigorously develop the industrialization of agriculture is to enhance the competitiveness of China’s agricultu re is an effective means of marketing innovation in agriculture. It is related to the industrialization of agriculture an important factor in business success. In this paper, product, place, promotion, three organizations, the face of the industrialization of agriculture marketing innovation of the corresponding development proposals. Keywords:Product;Channel Innovation;Promotion 1 Introduction Although China has already established a number of agricultural industrialization organization, but very few successful cases, reason, the product can not sell that influence their development, an important factor. At present the industrialization of agriculture organizations in product development, sales channels and marketing methods. There are many ways to solve urgent problems, we can say, marketing has become a bottleneck restricting development of the organization. In this Paper, the development of marketing concept, mainly based on the content of the theory of 4P, from development to meet consumer demand for products. Innovation in the channel, flexible use of marketing mix and so the organization seeking to promote the industrialization of agriculture marketing of innovative measures. 2 Development of Products to Meet Consumer Demand 4C theory holds that companies should give top priority to the pursuit of customer satisfaction, then theagricultural industry of the organization must first develop a customer satisfaction products. Marketing believes that demand for the
I. City and The Landscape (1) Overview of Landscape Design Landscape design, first, is a people's thinking activity, performed as an art activity.Diversified thoughts formed complex diverse landscape art style. Contemporary landscape design apparently see is the diversity of the landscape forms,in fact its essence is to keep the closing up to the natural order system, reflected the more respect for human beings, more in-depth perspective of the nature of human's reality and need, not to try to conquer the nature.it is not even imitating natural, but produce a sense of belonging. Landscape is not only a phenomenon but the human visual scene. So the earliest landscape implications is actually city scene. Landscape design and creation is actually to build the city. (2) The Relationship Between Landscape and Urban City is a product of human social, economic and cultural development, and the most complex type. It is vulnerable to the artificial and natural environmental conditions of interference. In recent decades, with worldwide the acceleration of urbanization, the urban population intensive, heavy traffic, resource shortage,
美国农业合作社与农业产业化外文文献翻译中英文最新 （节选重点翻译） 英文 Managing uncertainty and expectations: The strategic response of U.S. agricultural cooperatives to agricultural industrialization Julie Hogeland Abstract The 20th century industrialization of agriculture confronted U.S. agricultural cooperatives with responding to an event they neither initiated nor drove. Agrarian-influenced cooperatives used two metaphors, “serfdom” and “cooperatives are like a family” to manage uncertainty and influence producer expectations by predicting industrialization's eventual outcome and cooperatives’ producer driven compensation. The serfdom metaphor alluded to industrialization's potential to either bypass family farmers, the cornerstone of the economy according to agrarian ideology, or to transform them into the equivalent of piece-wage labor as contract growers. The “family” metaphor reflects how cooperatives personalized the connection between cooperative and farmer-member to position themselves as the exact opposite of serfdom. Hypotheses advanced by Roessl (2005) and Goel (2013) suggest that intrinsic characteristics of family businesses such as a resistance to change and operating according to a myth of unlimited choice and
Cover封面 Content目录 Design Explanation设计说明 Master Plan总平面 Space Sequence Analysis景观空间分析 Function Analysis功能分析 Landscape Theme Analysis景观景点主题分析图 Traffic Analysis交通分析 Vertical Plan竖向平面布置图 Lighting Furniture Layout灯光平面布置示意图 Marker/Background Music/Garbage Bin标识牌/背景音乐/垃圾桶布置图Plan平面图 Hand Drawing手绘效果图 Section剖面图 Detail详图 Central Axis中心公共主轴 Reference Picture参考图片 Planting Reference Picture植物选样 材料类： aluminum铝 asphalt沥青 alpine rock轻质岗石 boasted ashlars粗凿 ceramic陶瓷、陶瓷制品 cobble小圆石、小鹅卵石 clay粘土 crushed gravel碎砾石 crushed stone concrete碎石混凝土 crushed stone碎石 cement石灰 enamel陶瓷、瓷釉 frosted glass磨砂玻璃 grit stone/sand stone砂岩 glazed colored glass/colored glazed glass彩釉玻璃 granite花岗石、花岗岩 gravel卵石 galleting碎石片 ground pavement material墙面地砖材料 light-gauge steel section/hollow steel section薄壁型钢 light slates轻质板岩 lime earth灰土 masonry砝石结构
外文翻译一节水灌溉
河北农业大学 本科毕业（设计）论文 外文文献翻译 学院：城乡建设学院_____________ 专业班级：农业水利工程0901班 学号： _________ 2009224010113 ___________ 学生姓名： ____________ 周飞 ________________ 指导教师姓名: 指导教师职称：讲师_________________
二零一三年三月 Water-savins irrigation 1.Existing water-saving irrigation methods Irrigation methods, field water distribution method is how to have been sent to the farms, the irrigation water is evenly distributed to the active layer of the crop root. Irrigation water is the means by which to enter the active layer of roots, irrigation methods can be divided into surface irrigation, sprinkler irrigation, micro-irrigation and underground irrigation. U surface irrigation Surface irrigation is an ancient traditional irrigation method, in general, it is as compare whether water-saving basis points. Surface irrigation technology are constantly develop and constantly improve, so there are many more water-efficient than traditional surface irrigation technology. 1.1.1new furrow irrigation tools Traditional furrow irrigation with artiflcial opening from the distribution channel water into the furrow, it is neither accurate and inconvenient^ and often cause the field of water loss due to water port leakage countries have already adopted the siphon (for open channel water ) or gate hole pipe (aqueduct) drainage, China has done a number of tests, proven to improve field water utilization rate of 5% to 10%. 1.1.2surge irrigation Modern foreign developed wave Chung (groove) border irrigation or intermittent ditch (furrow) irrigation, traffic control into the ditch (furrow) is intermittent water and then put a period of time (a few minutes or tens of minutes) to field stop the water for some time (a few minutes or tens of minutes), and so forth, so that you can make along the ditch (furrow) the length direction of the water distribution is more uniform. Fields of water utilization up to 80% to 90%. Film hole irrigation (also known as the film hole irrigation) Gully, made on the film of water flow in the membrane, crops grow hole to penetrate the land, so that irrigation efficiency is high, generally water-saving 25% to 35%, an increase of 15% to 20%, they do not specifically facilities. 1.2Irrigation Sprinkler to spray through the air, due to the pressure of the commonly used pressure aqueduct In general, Its obvious advantages irrigation uniformity^ less of farmland, save manpower, strong adaptability to the terrain. The main disadvantage is influenced by wind, high investment in equipment. More in our country are the following: fixed pipe sprinkler, the semi-mobile pipeline sprinkler irrigation, a rolling shift sprinkler manifold, when the needle irrigation machine, a large pan spray irrigation machine, grain irrigation machine in inicroirrigators units and so on. 1.3drip irrigation Irrigation water with a small plastic tube directly sent to the the Meike crop roots near the
毕业论文外文文献翻译 毕业设计（论文）题目关于企业内部环境绩效审计的研究翻译题目最高审计机关的环境审计活动 学院会计学院 专业会计学 姓名张军芳 班级09020615 学号09027927 指导教师何瑞雄
最高审计机关的环境审计活动 1最高审计机关越来越多的活跃在环境审计领域。特别是1993-1996年期间，工作组已检测到环境审计活动坚定的数量增长。首先，越来越多的最高审计机关已经活跃在这个领域。其次是积极的最高审计机关，甚至变得更加活跃：他们分配较大部分的审计资源给这类工作，同时出版更多环保审计报告。表1显示了平均数字。然而，这里是机构间差异较大。例如，环境报告的数量变化，每个审计机关从1到36份报告不等。 1996-1999年期间，结果是不那么容易诠释。第一，活跃在环境审计领域的最高审计机关数量并没有太大变化。“活性基团”的组成没有保持相同的：一些最高审计机关进入，而其他最高审计机关离开了团队。环境审计花费的时间量略有增加。二，但是，审计报告数量略有下降，1996年和1999年之间。这些数字可能反映了从量到质的转变。这个信号解释了在过去三年从规律性审计到绩效审计的转变（1994-1996年，20％的规律性审计和44％绩效审计;1997-1999：16％规律性审计和绩效审计54％）。在一般情况下，绩效审计需要更多的资源。我们必须认识到审计的范围可能急剧变化。在将来，再将来开发一些其他方式去测算人们工作量而不是计算通过花费的时间和发表的报告会是很有趣的。 在2000年，有62个响应了最高审计机关并向工作组提供了更详细的关于他们自1997年以来公布的工作信息。在1997-1999年，这62个最高审计机关公布的560个环境审计报告。当然，这些报告反映了一个庞大的身躯，可用于其他机构的经验。环境审计报告的参考书目可在网站上的最高审计机关国际组织的工作组看到。这里这个信息是用来给最高审计机关的审计工作的内容更多一些洞察。 自1997年以来，少数环境审计是规律性审计（560篇报告中有87篇，占16％）。大多数审计绩效审计（560篇报告中有304篇，占54％），或组合的规律性和绩效审计（560篇报告中有169篇，占30％）。如前文所述，绩效审计是一个广泛的概念。在实践中，绩效审计往往集中于环保计划的实施（560篇报告中有264篇，占47％），符合国家环保法律，法规的，由政府部门，部委和/或其他机构的任务给访问（560篇报告中有212篇，占38％）。此外，审计经常被列入政府的环境管理系统（560篇报告中有156篇，占28％）。下面的元素得到了关注审计报告：影响或影响现有的国家环境计划非环保项目对环境的影响;环境政策;由政府遵守国际义务和承诺的10％至20％。许多绩效审计包括以上提到的要素之一。 1本文译自：S. Van Leeuwen.(2004).’’Developments in Environmental Auditing by Supreme Audit Institutions’’ Environmental Management Vol. 33, No. 2, pp. 163–1721
编号（学号）： 文献综述 （2012届本科） 题目：关于农业产业化发展的研究综述 学院： 专业：农林经济管理 姓名： 指导教师： 完成日期：2012年 4 月28 日 注：[封面的文献综述编号统一填写学号]
沈阳农业大学学士学位论文文献综述 关于农业产业化发展的研究综述 摘要：20世纪90年代初，“农业产业化”一经提出就成为理论界关注的热点, 农业产业化是我国发展农村经济、是国家增税、企业增利、农民增收的有效途径，是农业发展新的生长点和农业转向现代化的重要途径，是社会主义新农村建设的重要内容，是发展区域经济、推进城乡一体化、促进现代农业发展的现实选择，对我国“三农”问题的解决具有重大的现实意义。由于我国农业产业化起步晚，农业基础薄弱，规模化和产业化水平低,加之地区间发展存在极大的不平衡性，农业产业化仍然存在一些急待解决的问题，新农村建设为我国推进农业产业化提出了新要求。如何提高农业产业化的可持续性，是我们必须思考和研究的重要问题。现通过对近几年国内学术界的相关研究成果进行综述，以期对此问题的研究能够更进一步。 关键词：农业产业化；产业链；模式 中国是一个农业大国，农业是国民经济的基础，具有举足轻重的作用。2007年1月29日，《中共中央国务院关于积极发展现代农业扎实推进社会主义新农村建设的若干意见》下发，文件明确要求开发农业多种功能，健全发展现代农业的产业体系，要大力发展特色农业，扶持农业产业化龙头企业发展。此后的中央文件也多次提到了农业产业化发展的重要性。 从政府高度重视，到各项促进措施可以看出，发展特色农业，推进农业产业化的一直是农业经济发展的突破口，在建设社会主义新农村的宏伟工程里发挥着举足轻重的作用。我国农业产业化发展近20年，取得了很大的成就，农业综合增长力显著增强，基本实现了由粗放生产向集约化生产的历史跨越。但是随着现代农业发展进入关键时期，我国的农业产业化发展也迫切需要在体系上进一步创新，在质量上进一步提升。我国农业产业化最早是1993年在山东潍坊提出来的。它是指在农民家庭经营的基础上，以市场为导向，以经济效益为中心，通过各种类型的龙头组织的带动，围绕主导产业和产品，实行区域化布局、专业化生产、规模化建设、系列化加工、社会化服务、企业化管理，形成市场牵龙头、龙头带基地、基地连农户，种养加、产供销、内外贸、农工商一体化，农业产前、产中、产后各环节用利益机制联结成一体的一种生产经营组织形式。农业产业化则是实现农业两个根本转变和“第二次飞跃”的有效途径，是农村经营形式的重大改革和创新，也是农业发展新的生长点和农业转向现代化的重要途径，因此，调整农业产业结构、加快现代农业产业化进程便成为历史的必然选择。现将学者们的相关观点和研究成果梳理如下： 1关于农业产业化内涵界定的研究情况 第一种观点是：国外农业产业化最早产生于20 世纪50 年代的美国，美国哈佛大学的John M.Davis 和Roy A.Goldberg 出版的著作开创了农业产业化研究，但是, 当时他们提出的概念是Agribusiness, 我国翻译为农业综合企业, 简称农工综合体[1]。它是以
Forests, Trees and Livelihoods, 2010, V ol. 19, pp. 319–340 ? 2010 A B Academic Publishers—Printed in Great Britain Which role for the non farm-sector in a forested landscape? lessons from Krui, indonesia Koen Kusters* University of Amsterdam and Center for International Forestry Research (CIFOR) abstract this article explores two interrelated premises. the first is that the non-farm sector is of increasing importance to rural household. the second is that non-farm growth reduces the pressure on natural resources. the article reports on an analysis of income trends in three villages in the Krui area, sumatra, Indonesia, by comparing household survey data from 1995 and 2004. Between these two years, neither the farm sector nor the non-farm sector showed sustained growth.Although the contribution of remittances to local incomes remained marginal, migration of unemployed and unmarried youngsters to urban areas has a positive effect on per capita incomes in the Krui area by decreasing the household size. With regard to the second premise the analysis shows that increased engagement in local non-farm activities does not automatically result in smaller landholdings. Increased engagement in ex-situ non-farm activities, however, helps to reduce pressure on local forest resources. introduction the mainstream debate on conservation and development is based on the assumptions that agriculture is both the main threat to conservation and the main engine for rural development. Consequently, a large body of literature exists on the possibilities to reform agriculture in such a way that it better fits conservation goals. two main approaches are promoted. the first is to support environmentally friendly agricultural systems such as agroforests, in addition to protected areas (scherr and Mcneely, 2003; Ashley et al., 2006). the second approach is to encourage agricultural intensification and to decrease pressure on protected areas by increasing the returns on existing agricultural land (Mellor, 2002; Green et al., 2005). Both approaches have practical problems. Agricultural systems with high biodiversity tend to be less productive than intensive agricultural systems (Van noordwijk et al., 1997) and may not be competitive when the opportunity cost of land and labour increases (Belcher et al., 2005). on the other hand, increasing the income per hectare of land through intensification can act as an incentive for agricultural expansion (Angelsen and Kaimowitz, 2001) and may create other environmental damage as well, for example through the overuse of *e-mail address: K.Kusters@uva.nl