南北地震带的构造特色

南北地震带是以青藏高原地壳为主体和兼并了扬子地块西部而成的新生构造实体,具弥漫性边界。构成其基本格架的巨型反S形或缓弧形构造带,分布在中部的弧顶朝南的弧形构造以及发育在东界附近的旋卷构造,成为南北地震带的三大构造特色,它们都是塑性伸展流动的产物。据弧形构造形态实际数据分析表明,地壳物质向南移动的规模,由北往南逐渐加大,从西到东渐逐减小;自北纬31.5°往南,青藏高原物质东移量逐渐加大。     

Problems in the determination of plastic and liquid limits of remoulded soils using a drop-cone penetrometer

This short communication describes difficulties of sample preparation associated with the determination of plastic and liquid limits using a drop-cone penetrometer. Problems of sample packing, soil moisture distribution and degree of remoulding are identified. These problems are particularly relevant in influencing liquid limit values whilst the effects on plastic limits are less marked. It is concluded that if the need is for the quick determination of liquid and plastic limits for general classification purposes, then the traditional Casagrande and thread methods are adequate. If these limits require to be measured with greater precision using the drop-cone technique, then careful consideration must be given to sample preparation.     

The mechanics of spall fracture in rock and concrete

Spalling is a wave-induced dynamic fracture phenomenon. The waves can be either one: elastic, elasto-plastic, or shock waves. From a continuum mechanics point of view, fracture mechanics and wave propagation form the main ingredients in the formation of spalls. Recently, however, micro-structural effects have become important in the initial stages of spall formation in a variety of engineering materials ranging from metals to rock and concrete. From a structural geology point of view, the rock mass cannot be modelled as a continuum. In this case, a discontinuum approach has to be taken where the individual features of the rock mass such as joints and faults need to be taken into account. From an application point of view, spallation is important where rapid loading by explosives, impact, or energy deposition, occurs. The range of applications stretches from blasting in mining engineering to damage prevention to structures under explosive excitation.

This contribution offers a multi-faceted and multi-disciplinary approach to the study of spalling with special attention to analytical and experimental work. The reader is assumed to be somewhat familiar with the basics of continuum mechanics, fracture mechanics, and propagation of elastic, plastic and shock waves. The application to rock and concrete will show the effects of structural geological discontinuities such as open and closed joints - and to some degree also faulting - in rock, as well as the micro-structure of concrete on the (shock) wave field.

Extensive use will be made of time-space diagrams which proved very useful in practical applications to blasting problems [Rossmanith, H.P., 2002, The use of Lagrange diagrams in precise initiation blasting. Part I: two interacting blastholes, Fragblast 6, 104-136].     

The urban political ecology of plastic bag waste problem in Nairobi, Kenya

Over 24 million plastic bags are consumed in Kenya monthly. More than half of the bags end up in the solid waste stream. Plastic bags now constitute the biggest challenge to solid waste management in Nairobi, the capital of Kenya and home to three million people. As a result, plastic bag waste has attracted great political and public attention, especially because the waste has myriad unique environmental problems. This paper seeks to unravel the problem of plastic bag waste in Nairobi through an urban political ecological perspective. Urban political ecology has done much to excavate economic, political, and cultural processes, as well as ecological dynamics that create and re-create urban environments. Little has been done in this context with respect to urban solid waste problems, with the exception of urban political ecology of environmental justice. However, research done within the context of urban political ecology of environmental justice has mainly focused on solid waste problems in the Western World, particularly USA. Drawing on research conducted in Nairobi, as well literature on business and politics, and solid waste management in Kenya, this paper examines the nature of plastic bag waste problem, its political–economic roots and implications for environmental justice.     

The effect of plastic fines on the pore pressure generation characteristics of saturated sands

Pore water pressure generation during earthquake shaking initiates liquefaction and affects the shear strength, shear stiffness, deformation, and settlement characteristics of soil deposits. The effect of plastic fines (kaolinite) on pore pressure generation in saturated sands was studied through strain-controlled cyclic triaxial tests. In addition to pore pressure generation, this experimental study also focused on evaluating the threshold shear strain for pore pressure generation and the volumetric compressibility of specimens during pore pressure dissipation. The results reveal that specimens having up to 20% plastic fines content generated larger values of pore water pressure than clean sand specimens. At 30% fines content, the excess pore water pressure decreased below that of clean sand. The threshold shear strain, which indicates the strain level above which pore pressures begin to generate, was assessed for different kaolinite–sand mixtures. The threshold shear strain was similar for 0–20% fines (γ_t0.006–0.008%), but increased to about 0.025% for 30% fines. The volumetric compressibility, measured after pore pressure generation, was similar for all specimens. The transition of behavior at fines contents between 20% and 30% can be attributed to a change in the soil structure from one dominated by sand grains to one dominated by fines.     

Mechanism of accelerated dissolution of mineral crystals by cavitation erosion

Cavitation,a phenomenon produced by a moving fluid,is ubiquitous in the water environment of the Earth's surface and its related mechanical action in the process of cavitation leads to the widespread erosion of rock in nature.Although the mechanical action of flowing water body that accelerates the rock mass loss and fragmentation of rock(abrasion,erosion,and etching)and other phenomena have been much studied,its acceleration of mineral crystal dissolution is rarely reported.The physical mechanism of effect is not yet clear.The cavitation bubble produced in the cavitation process is at the micron level,and its related mechanical action leading to the accumulation of rock mineral dissolution is manifested in time and space in the process of the chemical element's migration between water and rock minerals.Cavitation erosion may be one of the important driving forces for the migration of geochemical elements within the lithosphere and hydrosphere.In this paper,based on the crystal dissolution stepwave dynamic theory and the theoretical derivation and calculation of Gibbs free energy change of the mineral crystals plastic deformation which caused by the mechanical action of cavitation erosion,we give the possible mechanism of accelerating the transient dissolution of mineral crystals by cavitation erosion—the cavitation bubbles on the surface of the near crystal release the high speed micro-jet and shock wave perpendicular to the surface during the collapsing,in which the water hammer pressure produced by micro-jet at the solid–liquid interface causes instantaneous plastic deformation on the crystal surface under the condition that it is larger than the yield stress of the crystal.Under the influence of the thermal effect of the plastic deformation process and the change of Gibbs free energy(the dislocation elastic strain energy of plastic deformation on the crystal surface may be included),the local instantaneous dissolution rate of the mineral surface is accelerated.The continuous cavitation erosion eventually causes fracture and breaking of the mineral crystal,meanwhile,the Gibbs–Thomson effect may enhance the dissolution of mineral crystals more prominently.At the same time,the correctness of the mechanism is verified qualitatively by the acoustic cavitation experiment with the same erosion mechanism.     

浅析塑料废物的处理与再利用

从我国塑料废物的处理现状及存在的问题出发,介绍了塑料废物回收再利用的方法,并提出了塑料废物污染的防治对策。     

石化企业工业设备震害经验分析

在国内外的大地震中，石油化工企业的震害经验是比较少的，过去的记载只是笼统地描述各类设备和构筑物的地震损坏情况，而与地震烈度相联系的定量说明却很少，看不出在各种地震烈度作用下震害的规律，因此整理并归纳内外七，八度地震烈度作用下石油化工设备和构筑物的震害情况，给出与地震烈度相联系的定量说明，使震害预测更有科学的依据。     

干旱地区春小麦耗水量和节水措施的探讨

本文研究了春小麦耗水量与产量的关系及其耗水规律，分析了土壤湿度、耗水量对春小麦生长发育的影响。结果表明：拔节至抽穗是春小麦的水分临界期，抽穗至成熟期耗水量最多，耗水模系数最大；产量与耗水量呈二次曲线关系，适宜土壤水分下限为：出苗至拔节期为田间持水量的70％-75％，拔节至抽穗期为60％-65％、抽穗至灌浆初期为55％-60％．灌浆初期至成熟期为50％-55％，本文还对春小麦覆盖地膜的节水增产原因及效果进行了探讨，提出了黑河流域春小麦节水增产的技术措施及进一步研究的意见。     

基于公众天气预报预测塑料大棚逐日极端气温

利用浙江省慈溪市的公众天气预报和草莓大棚内极端气温的观测数据,构建一个以室外日最高气温、最低气温、相对湿度、最大风级、白天和夜间天空状况作为输入变量,棚内日最高气温和日最低气温作为输出变量的BP神经网络预测模型。用以预测草莓大棚室内日最高气温和日最低气温。结果表明,该模型对大棚内日最高气温、日最低气温的训练值和实测值之间的均方根误差分别为4.0℃和1.3℃,绝对误差则分别为3.2℃和1.0℃;日最高气温和日最低气温的预测值和实测值之间的均方根误差分别为3.6℃和1.2℃,绝对误差为3.0℃和1.0℃。该模型数据获取方便,实用性强,模拟精度较高,可以较准确的预测未来温室内的极端气温,为温室管理和调控提供依据。