On Sustainable Development of Social Forestry in Bangladesh: Experiences from Sal (<Emphasis Type="Italic">Shorea Robusta</Emphasis>) Forests

Sustainability in forestry is a complex amalgam of trade-offs among its various dimensions and there is no easy route to achieve sustainable development. It is important that policy process and implementation strategy of these policies should be based on sound information about these trade-offs. There is a growing consensus amongst key forest decision-makers in Bangladesh that traditional forestry is needed to make the transition to more sustainable forestry, which is likely to involve local people in forest management. As a result, the government has initiated a social forestry program from 1981 with the assistance of the Asian Development Bank (ADB) loan and the United Nations Development Program (UNDP) grant and operated mainly in Sal forest areas. The most important objective of this program is to protect, manage, and develop forests in a sustainable way by involving local communities. Although several studies have focused on the management issues of social forestry, none of these studies has evaluated the indicators of sustainable social forestry. The purpose of this study is to evaluate the criteria of sustainable development of social forestry in Bangladesh. The study is based on primary cross-sectional data collected using the multistage stratified sampling technique. In total, 581 social forestry farmers were selected randomly and interviewed using a pre-tested questionnaire. The study evaluated some important components of sustainable development and identified the following conditions of social forestry in Bangladesh:(i) almost all the components of sustainable development of social forestry, although not at the aspiration level, were at good condition;(ii) participants were interested and committed to work with Forest Department in developing social forestry;(iii) they had been utilizing both hard and soft technology in practicing social forestry, although there exists ample scope of development;(iv) income of participants after involving in social forestry had increased, although not at satisfactory level; and(v) process of producing social and material goods had been under progress.However, there exist plenty of scopes for sustainable social forestry development through improving the sustainable development components more carefully.Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

软土地层地铁盾构施工风险可拓评估方法研究

为了综合评价软土地层地铁盾构施工风险,结合软土地层土质特点,选取地质复杂情况、地下水状况、最小覆土厚度、最小曲率半径、掘进长度、与临近周边环境距离和施工管理水平7个风险影响因素作为评价指标,采用简单关联函数法计算得到各评价指标的权重,避免了主观因素的干扰,运用可拓学理论建立了风险可拓评估模型,并将该模型应用于宁波轨道交通工程2号线栎社机场站-栎社新村站盾构区间的风险评估,得到该区间盾构施工风险等级为中度风险,评估结果较好地反映了工程的实际情况。     

软水中EPS对铜管/磷酸盐体系溶解性铜释放的影响

以海藻酸钠模拟水体中的细胞外高聚物(EPS)，研究软水体系中海藻酸钠对铜管／磷酸盐缓蚀行为的影响，结果表明：低浓度海藻酸钠能明显提高软水一铜管一磷酸盐体系中溶解性铜的释放，从而降低磷酸盐对铜管的缓蚀效果，而且从新管释放的溶解性铜远高于老化6个月、12个月和10年的铜管，释放溶解铜的顺序为Cnew＞C6m＞C12m＞C10y；随着海藻酸钠含量的增加，溶解性铜的释放浓度降低，但仍高于对照试验．在低pH条件下，海藻酸钠对溶解性铜的释放影响显著，从新管释放的溶解性铜浓度低于老化6个月、12个月和10年的铜管，这可能是由于不同老化时间的铜管其腐蚀表面的组成不同，水质pH值明显影响这些腐蚀副产物的溶解性铜释放；在不同停留时间内，随着水体组成的变化，溶解性铜的释放浓度不断发生变化，表明海藻酸钠与铜离子形成的络合物影响磷酸与铜的相互作用，从而影响磷酸盐对铜管的缓蚀效果．     

Artificial Sampling Units: A Tool for Increasing the Sensitivity of Tests for Impact in Soft Sediments

The distribution of benthic organisms in soft sediments is patchy in time and space on many scales. Such variability makes assessment of ecological impacts difficult. Sediment-related variables, such as grain-size and organic content, which can affect colonization by infauna, vary over similar scales. Variations in characteristics of the sediment may contribute to spatial variability in infaunal assemblages, making it difficult to detect the putative impacts of disturbances, such as the production of boat-generated waves (wash), on these organisms. Here, the hypothesis that infaunal assemblages colonizing containers of homogeneous sedimentwould be less spatially variable than those colonizing natural sediment was tested. Containers were deployed at mudflats differing in exposure to wash. If wash does affect colonization, a reduction in variability among sites of similar exposure should enable stronger differences to be seen between wash and no-wash zones. Assemblages colonizing homogeneous sediment were less variable than those colonizing site-specific sediment. No difference in colonization was, however, seen between places differing in their exposure to wash. Nevertheless, this method is of use in the assessment of ecological impacts in sedimentary environments, where it is difficult to detect putative impacts above the great natural variability in assemblages.     

高地应力软岩隧道初期支护优化研究*

为研究边墙曲率、支护参数等因素对高地应力软岩隧道变形控制的效果,以大瑞铁路营盘山隧道为工程背景,结合现场监测数据,建立有限元模型,分析不同边墙矢跨比及初期支护参数对隧道变形的影响,借此得到合理的初期支护参数。结果表明:原有支护结构中“直边墙”对于隧道水平方向变形与压力抵抗能力较弱,当边墙曲率调整至0.12后,支护结构的受力和变形情况得到明显改善;初期支护参数中锚杆参数对于隧道变形控制效果较小,增强衬砌的强度可以有效控制隧道的变形;通过围岩-支护特征曲线对优化后的支护方案进行安全评价,发现其安全性能较之前显著增强,现场应用结果也表明支护结构并未出现破坏失稳现象,隧道变形得到有效控制。研究结果对类似工程变形控制及支护方案优化提供一定的参考依据。     

双护盾TBM不良地质段卡机脱困技术研究*

为确保双护盾TBM在不良地质中遭遇卡机事故时能快速安全脱困,依托某引水隧洞工程,研究双护盾TBM在断层破碎带段及软岩大变形段遭遇的卡机事故原因以及采用超前大管棚支护、环形扩挖法的技术难点。结果表明:双护盾TBM在断层破碎带段采用超前大管棚支护及软岩大变形段采用环形扩挖法,均能解决卡机事故问题,使其成功脱困。研究结果可为类似TBM卡机脱困提供工程借鉴。     

软煤样断裂韧性加载速率效应实验研究*

为探究加载速率对软煤样Ⅰ型断裂韧性的影响,对取自云南老厂的煤样开展压入硬度实验及不同加载速率条件下的断裂韧性实验,分析加载速率及割理角度对软煤样断裂特性的影响。结果表明:实验老厂煤岩压入硬度分布在51.84～125.03 MPa之间,按压入硬度划分属于软岩类别;实验岩样Ⅰ型断裂韧性分布在0.009 9～0.208 2 MPa·mm^0.5之间,平均值为0.096 5 MPa·mm^0.5;在0.2～1.1 mm/min的位移加载速率范围内,实验软煤岩Ⅰ型断裂韧性值随加载速率的增大呈现先增大后降低的规律,割理角度对软煤岩Ⅰ型断裂韧性有较大影响,Ⅰ型断裂韧性与割理角度的关系呈现为负线性相关性。低加载速率条件下,软煤岩表现为韧性断裂,高加载速率条件下,软煤岩表现为脆性断裂,加载速率的变化导致软煤岩断裂类型的变化。     

Natural purification effects in the river in consideration with domestic wastewater pollutant discharge reduction effects

The first social experiment program in Japan to reduce domestic wastewater pollutant discharge by “soft interventions” in households has been conducted in the Yamato-gawa River drainage area since 2005. The Yamato-gawa River has been listed as one of the worst water quality rivers in Japan because of the larger annual average BOD. “Hard interventions” including deployment of wastewater treatment facilities and artificial installation of natural purification facilities in the river has been conducted in these years to improve river water quality. At the first Yamato-gawa River social experiment program (YR-SEP) in March 2005, BOD at the monitoring point near the river mouth decreased about 6% during the Program. Natural purification e ect along the river was evaluated in this article with one-dimensional water quality model for the six river sections. Larger biological oxygen consumption rate, kb, was estimated in the sections with artificially installed natural purification facilities. The e ect of “soft interventions” in households in the YR-SEP was estimated as 25% BOD decrease in the nearest monitoring point to the river mouth, when all the households participate in the Program and BOD discharge reduction rate with “soft interventions” in households was 40%.     

泥质软弱破碎矿脉浅眼回采控制爆破试验研究

针对前河金矿泥质软弱破碎矿脉下向进路回采过程中超爆、上下盘围岩大面积垮塌、爆破后支护作业困难等问题,在总结分析软弱破碎岩体爆破特性的基础上,基于减震控制爆破基本理论,提出了“预留顶板充填体减震层、径向不耦合装药、控制边眼装药量、秒延期多段别控制起爆”等系列综合减震控制手段,据此分别针对Ⅳ级和Ⅴ级破碎岩体提出了2种具体的浅眼回采控制爆破技术方案,并进行了现场回采爆破试验。试验结果表明:所提出的2种方案均能够有效的控制回采边界,爆破后进路顶板充填体和上下盘围岩完整性良好,为后续采场出矿、支护等创造了有利的时空条件,且炸药单耗较原方案均有所降低。研究成果可分别在矿区范围内类似条件下推广应用。