基于非对称双侧破坏模式的临坡地基承载力上限分析

临坡地基已成为一种广泛的地基形式。针对临坡条形基础地基破坏模式的非对称性特点,首先引进双侧破坏模式的研究思路,重点考虑临坡地基基础两侧滑块大小和同一滑块几何形状的双重非对称性特征,构建了临坡条形基础地基非对称双侧破坏模式,为临坡地基承载力分析奠定了坚实基础;然后在此基础上,引进极限上限分析和优化理论,建立了临坡条形基础地基承载力分析的模型与方法,该方法不仅可考虑地基破坏模式,还可考虑基础与坡顶距离对临坡地基承载力的影响,而且还可较好地蜕化为平地地基承载力的分析;最后通过工程实例计算,并与现有相关分析方法进行对比分析,表明该方法的可行性与合理性以及普遍适用性。     

华东南地区5.5级以上地震前的地震活动图像异常研究

对华东南地区1970年以来5.5级以上地震前的地震活动空间图像进行了分析, 发现震前多有不同程度的地震条带、 空区或增强异常出现。 所研究的9次地震中, 有4次震前出现了地震条带异常, 3次出现了地震空区异常, 4次出现了地震活动增强, 出现2种以上异常的地震有4次。 条带、 空区与主震的相对位置表明, 主震发生在条带内部的比例与边缘及外侧相当, 主震全部发生在空区内部。 条带、 空区相对于发震断层走向的角差小于30°的比例分别为33%和60%。     

Micrometeorological measurements and vapour pressure deficit relations under in-field rainwater harvesting

In a cropped field, microclimate and thermal stability conditions depend on the canopy structures and the prevailing weather. The main aim of the study therefore was to characterize the vertical profiles of weather variables within and above a maize (Zea mays L.) canopy and to describe the water vapour pressure deficit (VPD) under different atmospheric and soil surface conditions for both wide and narrow runoff strips with the in-field rainwater harvesting (IRWH) system. Micrometeorological measurements of wind, temperature and relative humidity were performed at eight levels, within canopy (1.8 and 2.1 m), and just above the canopy (2.4, 2.7, 3.0, and 3.3 m) up to reference levels (3.9 and 4.5 m) when the maize reached a maximum height of 2.2 m. Under incomplete canopy cover of the IRWH system, two important factors complicated evapotranspiration estimation, namely the local advection and high temperatures of the bare soil between adjacent plant rows. Diurnal variations of water vapour related to turbulence at each locality and its position in the thermal internal boundary layers. Generally, advection was more pronounced in wide runoff strips than narrow strips. On wide runoff strips the wind was more effective in replacing the air between the rows and maintained a higher driving force for evaporation. The maximum VPD over the narrow strips was observed at reference level during a dry day, at about 2.2 kPa in the afternoon, while wet day VPD reached a maximum of 1.8 kPa. The VPD of the wide runoff strips correlated negatively with wind speed, but showed a fairly positive correlation with some scattered values on wet days after rain. Therefore, profile characteristics within and above plant canopies played a key role in determining the VPD and consequently, could help to explain transpiration rates of crops. Hence, VPD relations enhanced the understanding of the heat energy exchange processes under the heterogeneous nature of maize canopy of the IRWH tillage system.     

露天矿采场时空数据模型的构建与应用

以地理信息系统技术为核心,建立露天矿采场时空数据库,通过构建采场的时空数据库,动态描述露天矿生产的剥、采、排过程,为露天开采的规划、设计、生产调度管理的优化预控决策提供全方位的空间信息支持。提出考虑台阶特征的不规则三角网（TIN）的露天矿采场三维建模理论与方法,采用基于基态修正和时间快照模型构建露天矿采场时空数据库,通过地理信息系统和虚拟现实技术,实现开采过程的回放和生产计划的超前演示,为数字露天矿建设构建基础的地理空间信息框架与平台。     

夏季南海西部叶绿素浓度高值带的年际变化

基于1998-2013年SeaWiFS和MODIS传感器的叶绿素浓度资料,本文分析了夏季南海西部叶绿素浓度高值带的年际变化规律。夏季,叶绿素及营养盐在海流的作用下离岸输送,从而在南海西部形成叶绿素浓度高值带,其分布与东向急流的流向一致。分析结果显示,高值带分布主要受13°N以南海域风场的调控,且滞后风场1周。当13°N以南海域受异常东北风（西南风）控制时,高值带位于其多年平均位置以北（南）。     

Laboratory modeling of siphon drainage combined with surcharge loading consolidation for soft ground treatment

Conventional drainage consolidation methods cause significant energy consumption and environmental issues. In this paper, a method combining siphon drainage and surcharge loading is proposed to drain water from soft soil with vertically installed prefabricated vertical drains (PVDs) and a siphon tube. To investigate the availability and effectiveness of this method, a laboratory physical modeling test was conducted to investigate the drainage and consolidation behavior. The laboratory modeling test results of this method were compared with the calculated results of the ideal sand-drained ground consolidation method to clarify the advantages and mechanism of this method. Comparison results show that the pore pressure and settlement in the proposed method developed faster than the calculation results of ideal sand-drained consolidation theory. About 10?m thickness of unsaturated zone can be formed by siphon drainage which produce a surcharge loading effect on the soil below the flow profile. Drainage is a very slow process in soft soil, and siphon drainage can work continually. Siphon drainage combined with surcharge loading is potentially a good alternative to drain water from soft clay economically and environmentally.     

被动排桩弯曲性状的三维有限元分析

利用三维非线性弹性有限元方法,研究了承受邻近地面超载作用时被动排桩的弯曲性状,也研究了排桩间距变化、地基软弱下卧层以及超载与排桩之间的距离对桩身弯曲性状的影响,揭示了邻近超载作用下被动排桩桩身弯矩和挠度的变化规律。研究表明,在邻近超载作用下桩身最大正弯矩出现在0.55倍桩长处,桩顶部也产生较大的负弯矩,随着超载的增大,负弯矩由增大变为减小,桩身正弯矩增大,当超载超过一定值时,桩身正弯矩加速增长;桩身的弯矩随着桩距的增大而增大;当地基中存在软弱下卧层时,桩身的负弯矩减小,而正弯矩明显增大。     

石漠化治理对土壤中CO2、CH4变化特征及碳汇效应的影响

为探究石漠化治理对土壤中CO2、CH4变化特征及碳汇效应的影响,采用气相色谱法对重庆市南川石漠化治理示范区土壤中CO2、CH4浓度进行观测,结合土壤温度、土壤含水率、土壤容重和土壤有机碳对石漠化治理区（试验区）和对比区（未经过石漠化治理的荒草地）进行研究,并用溶蚀量数据估算岩溶区碳汇量。结果显示:土壤中CO2浓度随土壤深度的增加先增加后减小,变化范围为393～7 400 mg·L-1;而土壤中CH4浓度随土壤深度的增加先减小后增大,变化范围为1.13～3.42 mg· L-1。试验区土壤中CO2浓度均值为2 131 mg· L-1,CH4浓度均值为1.94 mg· L-1 ;而对比区土壤中CO2浓度均值为2 338 mg· L-1,CH4浓度均值为2.10 mg·L-1。土壤温度、土壤有机碳与土壤中CO2浓度变化趋势呈显著正相关关系,而与土壤中CH4变化趋势呈显著负相关关系,说明土壤温度和土壤有机碳是影响土壤中CO2、CH4浓度的主要因素;土壤温度与土壤中CO2浓度呈正相关关系且相关性随石漠化治理而变弱,说明经过石漠化治理土壤温度对土壤中CO2浓度的影响减弱。试验区岩溶试片溶蚀速率大于对比区,且经过石漠化治理,由岩溶作用产生的碳汇可提高0.66～9.42 t·km-2·a-1 ;说明石漠化治理对于岩溶区碳汇起到了促进作用。      

高边坡结构可靠度的二次处理有限元分析

本文依据强度折减理论,利用MIDAS/GTS有限元软件,分析计算了高边坡结构的安全系数K,找到边坡滑裂带的位置。在此基础上,对有限元输入数据和输出结果进行二次处理,建立基本随机变量c,f与滑裂带中单元的最大(和最小)主应力1(和3)的拟合关系f1(和f3),将其代入高边坡结构的功能函数Z中,使Z由隐式形式变为显式。基于该显式表示的Z,利用Monte Carlo法计算滑裂带中所有失效单元的可靠指标1,并将其单元面积A1作为权重系数,经过加权平均得到边坡结构的整体可靠指标。上述方法使得结合有限元软件计算边坡结构的整体可靠度得以简化。经实例分析可知,本文提出的方法是合理可行的,可使边坡结构整体可靠性分析得以简化,也可为高边坡结构整体可靠性分析提供理论参考。     

条带法在底板承压水上采煤中应用的数值模拟研究

近年来,条带法被用来作为承压水上采煤的主要采煤方法。针对承压水上采煤问题,应用流固耦合原理,将孔隙介质中孔隙压力与应力建构在统一的本构模型中,平行计算应力场与渗流场,其实质是煤岩体体积应变对孔隙的影响通过流动本构定律加以反映;反之孔隙压力的变化可引起煤岩体变形。应用FLAC有限差分软件对条带式和长壁式采煤方法的应力发展和岩体破坏情况进行模拟并进行比较分析,证明条带法在降低由采动引起的应力影响范围和程度,从而减小煤层底板破坏程度和范围(主要是深度)的有效性,为合理确定承压水上采煤的开采方案提供了理论依据。