Theoretical investigation of large-amplitude waves in granular soils

A theoretical investigation of plane waves in granular soils is presented. Dynamic equations are derived with the use of the hypoplasticity theory for granular materials. For numerical calculations the material parameters of Karlsruhe sand are used. Wave speeds as slopes of characteristics of the dynamic equations are calculated for various stresses and densities. It is shown that under certain conditions the dynamic equations lose hyperbolicity and the initial boundary value problem thus becomes ill-posed. Two types of ill-posedness are found, known as flutter ill-posedness and stationary discontinuity. The latter is shown to arise at higher shear stress than the former. A comparison is made between dynamic ill-posedness and stability of static equilibrium. With the use of the second-order work stability criterion it is found that the dynamic equations lose hyperbolicity when the static equilibrium under a dead load is still stable. Numerical solutions to the problem of propagation of boundary disturbance in a half-space are obtained. Owing to dilatancy and contractancy of the granular material, a purely transverse disturbance induces a longitudinal component of velocity in the wave, and vice versa.     

武汉白沙洲长江大桥百米长桩成孔技术与施工实践

介绍了百米长桩的施工方法、施工设备、护孔技术,并就深孔实施泵吸反循环的可行性、主要技术措施以及强风化岩层的糊钻问题进行了分析。     

基坑支护结构施工技术要点与工程实例分析(下)

４地下连续墙施工技术方法４．１要点（１）导墙的修筑精度（宽度、平直度、垂直度和标高等）和强度对成槽施工质量有直接影响,高质量的导墙是高质量槽段的基础,常用的导墙形式如图２所示。图２导墙断面形式示意图（ａ）板型;（ｂ）Ｌ型;（ｃ）倒Ｌ型;（ｄ）槽型导墙...     

软土层施工桩基的新方法滚压法

介绍软土层用新型孔底工具－滚压器施工桩基的工作原理、施工工艺,滚压器基本结构及不同直径滚压器的技术特征。     

反射波法检测桩身完整性的一种数据处理方法

本文以纵波在杆中传播的理论为根据,介绍一种用于确定反射波往返时及视反射系数等参数的方法。将视反射系数经过一定的校正后,可定量分析反射界面的波阻抗差异的大小,进而确定桩身缺陷的严重程度;反射波往返时则用来推算桩身缺陷的位置。     

滁州市会峰大厦桩基垂直静荷载试验研究

本文根据滁州市会峰大厦人工挖孔扩底桩的垂直静荷载试验成果,分析研究了滁州市红砂岩地基嵌岩桩的荷载有受力特征。     

深基坑锚杆护坡桩支护结构稳定性评价

锚杆护坡桩是深基坑工程常用的一种支护结构。文中对设计中所涉及到的结构稳定性评价问题进行了探讨,利用Ｋｒａｎｚ理论一些假设和条分法原理,提出了深基坑锚杆抗护坡桩稳定性评价的方法。该方法克服了Ｋｒａｎｚ理论中的一些不足,简化了条分法的计算并通过支护工程验证,具有一定的实用价值。     

Magma traps: Part II,application

A model of the lithostatic control of the ascent of magma, described in Part I (this volume), is tested against data from the Upper Cretaceous-Lower Tertiary sedimentary and volcanic region of central West Greeland: the thickness of sedimentary rock; the thickness of the pillow breccias; the total thickness of the lava pile; the depth of the post volcanic paleosurface. The local development is largely determined by a single parameter, the proportion of crustal thinning, and requires a magma source at 75 km depth with differentiation at 11 km depth. The model is applied in outline to the development of continental and orogenic volcanism in New Zealand.     

涡旋诱发磁重联模型的解析研究

在磁流体中涡旋诱发重联的线性过程的解析研究过程中,主要运用了渐近匹配展开方法．结果表明,如果流体粘性远大于磁粘性,流场马赫数Ma～1,重联的线性增长率正比于Vv为无量纲化流体粘性,这与数值模拟结果一致．此结论表明,流体粘性能够促进磁场重联,在理论上支持涡旋诱发重联模式．本文还研究了周期分布多电流片系统中涡旋诱发重联的线性增长率;随电流片之间距离的减小,反对称和对称情形的增长率分别增大和减小．     

Lateral translocation of soil plasma through a small valley basin in the Northaw Great Wood,Hertfordshire

The paper looks at the process of lateral translocation in a small valley basin from the Northaw Great Wood, Hertfordshire. The valley basin comprises four lithostratigraphic units (London Clay and Pebble Gravel, and the others a mixture of these two), which were initially established in the field by a rough assessment of texture. Particle size analysis validated the lithostratigraphic units as delineated in the field; it was found unnecessary to alter the boundaries of the units. Patterns of lateral translocation of silt and clay (measured by the hydrometer method) and the amorphous colloidal hydrous oxides and hydroxides of Al, Fe, Mn and Si (measured in oxalate solution by atomic absorption spectrophotometry) are inferred from balance sheets of the relative gains and losses of the materials. Materials from horizons formed in lithostratigraphic units derived from London Clay are balanced against a clay dilution factor; those from the lithostratigraphic unit of Pebble Gravel against the dilution of sand on a clay-free basis. The results lead to the following conclusions about the process of lateral translocation: it has been a significant contributor to soil development; larger amounts of material have moved down-slope towards the hollow than over the nose because there has, theoretically, been more throughflow in the hollow; for some materials there has been less down-slope transport in lower horizons owing to less throughflow in them.