The Assessment of Natural Spill Incidents based on Resource Damages Caused by Oil Equivalency Analysis Methods

尽管国际公约和许多国家立法已将海上溢油事故导致的自然资源损失列入索赔范围,然而,在量化和货币化损害以及确定索赔和修复范围等方面尚未建立被广泛接受的计算方法。生境等价分析（Habitat Equivalency Analysis,HEA）和资源等价分析（Resource Equivalency Analysis,REA）是美国和欧盟应用于评估自然资源损害的理论方法,二者的关键假设是受损的生态服务损失和修复计划的服务收益应当相等。HEA结果依赖于生态服务价值标尺选择、服务价值水平、恢复曲线形状、修复计划时长以及贴现率等;REA结果受死亡生物数量和年龄组成的影响。HEA和REA的非货币形式结果补偿的并非生态环境,而是人类社会福祉。目前,一些货币化损失的方法已被提出,然而传统经济学家和生态经济学家之间存在争议。美国部分法庭承认HEA和REA方法,其结果为法庭索赔提供数据支持。如果将生态学和经济学原理结合考虑,将能够促进等价分析法的深入发展,推动索赔工作更加有理有据。     

膨胀土初始破损与湿干交替耦合作用下的力学行为

为研究不同初始破损程度、不同干湿循环次数及两者耦合工况对膨胀土孔洞及裂隙发育、演化规律的影响,以及相应的土体变形、力学行为,以合肥膨胀土为研究对象,对制备的不同初始破损程度（圆柱孔直径分别为0、2.5、5 mm）的3组20个试样进行干湿循环试验及三轴剪切试验（控制吸力为50 kPa,有效围压分别为100、200、400 kPa）。并解释了孔洞-裂隙的产生及发育新机制。结果表明：干湿循环次数为0时,一定程度的初始破损会提高土体的强度;与常规认识不同,干湿循环次数为1～2次时,初始破损的存在会诱导土体裂隙开裂的方向和贯通模式,形成的结构块较无破损土体形成的更完整,因而具有相对于无初始破损土体更高的强度;干湿循环次数为3次时,裂隙完全扩展,土体结构性被严重破坏,有无初始破损的土体强度趋于一致;孔洞-裂隙的演化机制是：脱湿-增湿过程中产生的水力梯度使土体具有不同的软硬性质和胀缩变形,产生的拉压应力在微裂纹、尖端形成应力集中而开裂,更易与具有的初始孔洞破损联合、交汇、贯通,萌生的裂隙增大了水汽交换界面面积,进一步平衡拉压应力而最终完全碎裂。研究可为普遍存在初始破损的膨胀土工程研究提供新的思路。     

单轴压缩黏性土剪切带相互作用及损伤试验研究

剪切带损伤研究对于理解材料破坏机制和建立剪切带本构模型具有重要意义。为了研究单轴压缩黏性土样的剪切带损伤演化规律,根据纵向应变较高时清晰剪切带位置布置切向测线,对数字图像相关方法获得的结果进行双三次样条插值,从而获得光滑性较好的各种应变场。将土样整体的损伤变量-纵向应变曲线与各条剪切带的损伤演化曲线进行了对比。研究发现：（1）总体上,土样整体的损伤变量演化曲线呈线性,而各条剪切带的损伤变量演化曲线均上凹,这表明随着纵向应变的增加,各条剪切带的损伤发展越来越快;（2）各条剪切带的损伤变量演化曲线的轮廓线呈马尾形,这说明随着剪切带的逐渐发育,各条剪切带的相互影响和作用规律变强;（3）对于含水率较低的土样,平行或共线剪切带的损伤变量变化基本同步,特别是在剪切带充分发育之后,但两条剪切带的距离应较小;在一定时期,共轭或交叉剪切带中剪切带的损伤占优,这与剪切带的相互竞争有关,但若两条剪切带达到独立发展的程度,则二者的损伤变量变化可以同步;对于含水率较高的土样,各条平行或共轭剪切带的损伤变量变化基本同步,剪切带的相互作用不明显。     

含水状态下软岩蠕变试验及损伤模型研究

为考虑时效劣化和含水弱化对岩石蠕变参数的劣化效应,提出了蠕变损伤模型,即对西原模型进行参数修正与完善,开展了不同含水状态的软岩三轴蠕变试验。首先,对不同含水率的岩石蠕变规律进行了对比分析,初步揭示了含水状态对岩石蠕变过程影响规律的机理。其次,为了能够较好地描述岩石蠕变过程,引入时效劣化效应和含水弱化效应,并通过试验数据拟合了损伤变量和蠕变参数。最后,将模型的计算值与试验值进行对比分析。结果表明,岩石随着含水率的增大,初始蠕变值和稳态蠕变值有所增大。通过FLAC3D验证了该模型的数值计算值与试验值具有很好的吻合性,提出的岩石时效蠕变损伤模型将为岩石流变特性的研究提供一定的理论基础。     

沁水盆地柿庄南区块煤层气井储层压降类型及排采控制分析

为了充分认识柿庄南区块煤层气井储层压力变化特征及其对煤层气井产量的影响,基于对柿庄南区块储层地质参数的分析及实际生产数据的剖析,对不同类型生产井的储层压降类型进行分析归类,并结合排采异常井对气井低产原因、排采控制方法及储层敏感效应进行具体分析。结果表明：柿庄南区块煤层气井储层压降可分为快速下降型、中期稳定型及缓慢下降型3种类型,其中快速下降型井更有利于煤层气高产稳产,但若降压速率超过快速下降型井的最大降压速率反而会使储层受到压敏、速敏效应,降低储层渗透率,同时导致压降漏斗扩展受限,最终抑制煤层气井达到高产稳产。     

冻融循环条件下片麻岩蠕变特性试验研究

为探讨寒冷地区隧道围岩的长期稳定性,选取吉林省辉白隧道中的片麻岩进行冻融循环条件下的三轴蠕变试验,分析了冻融循环作用对片麻岩蠕变特性的影响机制。试验结果表明：随着冻融次数的增加,片麻岩的蠕变变形量逐渐增加,而蠕变破坏应力、蠕变时长、长期强度均有明显降低的趋势。同时冻融循环温度的幅度对片麻岩的各蠕变参数也有一定影响,表现为冻融循环次数相同时,温度越低,岩样的初始瞬时蠕变越大,而蠕变时长与长期强度越小。同时基于试验结果,利用1stOpt优化软件对Burgers模型参数进行辨识,可得模型理论曲线与试验曲线在蠕变减速段和稳定段吻合较好。最后通过SEM扫描和能谱EDS分析了冻融循环对片麻岩微细观结构的影响机制。岩样在长期荷载作用下的破坏模式均为剪切破坏,随着冻融次数的增加,岩石的破裂程度越来越严重、破坏块度越来越小。研究结果为寒区岩石工程的支护设计和防冻害设计提供了参考和依据。     

花岗岩热损伤特性研究

通过对花岗岩在20 ℃～600 ℃范围内基本力学性质的研究,探讨了弹性模量、单轴抗压强度以及泊松比随温度的变化规律,发现75 ℃和200 ℃分别为花岗岩弹性模量和单轴抗压强度的门槛温度。以弹性模量为研究对象,提出了热损伤的概念,并给出了热损伤本构方程的一般表达式;在Lemaitre损伤模型的基础上,推导了一维TM耦合弹脆性损伤本构方程和损伤能量释放率的表达式;参照经典塑性力学的屈服面理论,引入了温度作用下应力空间中脆性岩石的损伤面模型,定性地讨论了荷载和温度影响下损伤面时的演化规律。     

不同围压下砂岩的变形力学特性与损伤机制

开展不同围压下砂岩的强度、变形和损伤演化研究,对岩体工程的结构设计和稳定性评价具有重要意义。对赵固一矿二1煤层顶板砂岩进行试验获得其力学参数,并采用颗粒流程序获得砂岩细观力学参数,结合编制的fish语言程序进行试验,研究砂岩在不同围压的强度、变形和损伤演化机制,得到如下结论:随着围压增加砂岩的屈服段变长,围压小于40 MPa时峰值强度随围压变化敏感,大于40 MPa时敏感性降低,随着围压增加砂岩由脆性破坏逐步转变为延性破坏;砂岩的扩容经历线性体缩、线性扩容和非线性扩容3个阶段,围压增大线性扩容阶段缩短而非线性扩容阶段增加,扩容指数和扩容起始点轴向应变与围压存在指数变化规律;砂岩的损伤破坏经历损伤弥散分布、聚集成核、形成局部裂隙和主控破裂面形成4个阶段,低围压下砂岩沿单一主控破裂面发生压剪破坏,高围压下主控破裂面呈X型交叉破坏岩体,为X型共轭斜面剪切破坏形式。     

Integration of a continuum damage model for shale with the cutting plane algorithm

The stability of integration is essential to numerical simulations especially when solving nonlinear problems. In this work, a continuum damage mechanics model proposed by the first author is implemented with an integration method named cutting plane algorithm (CPA) to improve the robustness of the simulation. This integration method is one type of return mapping algorithm that bypasses the need for computing the gradients. We compare the current integration method with the previous direct method, and the result shows that the cutting plane algorithm exhibits excellent performance under large loading rate conditions. To enhance accuracy of the new method, a control procedure is utilized in the implementation of the algorithm based on error analysis. Thereafter, the theory of poromechanics is utilized with the damage model to account for the effects of fluid diffusion. Laboratory tests simulated with finite element method illustrate distinct behaviors of shale with different loading rates and indicate the development of microcrack propagation under triaxial compression. Copyright © 2016 John Wiley & Sons, Ltd.     

Hazard Assessment of Cold and Hot Damage for Double-Season Early Rice (DSER) in Lower-Middle Reaches of the Yangtze River Basin

Cold and hot damages which are both common disasters occurring in DSER growth time in lower-middle reaches of the Yangtze River Basin harm early rice. The two disasters occurrence should be deeply studied to protect the DSER yield. This study was based on meteorological data of 48 agricultural meteorological stations during 1961-2010 period and agricultural meteorological data during 1981-2010 for DSER in lower-middle reaches of the Yangtze River Basin. In this study, the growth time was divided into several phases according to the growth stage, including tillering stage, booting stage, flowering stage and filling stage. The disasters taking place at some stages was identified by building new judging standard and their intensity value was calculated by harm accumulated temperature calculation model. Fisher optimal division method was used to classify the disasters and H-P filter was used to consider the reduction of the yield. It was conducted to analize the disasters’ characteristics in growing season, the intensity of hazard and the weight of hazard at each stage by judging and quantifying cold and hot damage and developing hazard assessment model of disasters. All findings were displayed in maps by GIS technology. The results showed that: ①New disaster judging standard was more suitable for DSER and the hazard assessment model could reveal the disaster situation in lower-middle reaches of the Yangtze River Basin. ②Cold damage was severe at tillering stage while hot damage was severe at filling stage. In the view of the distribution of the decadal disaster intensity, cold damage became to be weak and hot damage became to be strong. Compared with the plains, mountainous region and hilly ground were attacked by cold damage frequently and hot damage rarely from the perspective of spatial distribution of disasters. Distinctly, plains near large areas of water were often harmed by cold damage at booting and flowering stage. ③The area of high hazard value and high disasters value at each stage were overlapped by each other roughly. Studying the hazard of the whole growth season showed that the highest hazard value was in Zhejiang province, and the next in Hubei Province. So Hu’nan and Jiangxi Provinces were quite suitable to grow DSER. ④In contrast with the hazard weight at each stage, the vulnerable phases of the whole growth time were in sequence of filling stage> tillering stage> flowering stage > booting stage. What’s more, aiming at defensing and fending off risk, some special stages in special province should be paid close attention including booting and filling stages in Hubei Province, tillering and flowering and filling stages in Hu’nan Province, tillering and filling stages in Jiangxi Province, flowering and filling stages in Zhejiang Province. The conclusion can be taken as theoretical basis for the government management of agricultural production, disaster prevention and mitigation.