路堤下现浇薄壁管桩复合地基工作特性分析   总被引：15，自引：7，他引：15  

费康  刘汉龙  高玉峰 《岩土力学》2004,25(9):1390-1396

现浇薄壁管桩和土工格栅加筋碎石垫层所组成的复合地基加固软弱路基具有经济合理，施工时间短，承载力高，沉降减小明显等优点。采用非线性有限元对路堤荷载作用下的现浇薄壁管桩复合地基的工作特性进行了分析，结果表明：在路堤荷载作用下，路堤填土材料中的拱效应、土工格栅的拉膜效应或加筋垫层的刚性垫层效应、桩土间刚度差异引起的应力集中效应保证了大部分荷载由桩承担，有效地减小了总沉降和不均匀沉降。同时对荷载传递机理的影响因素做了分析.  相似文献   

水泥搅拌桩与锚杆组合支护结构的力学参数研究   总被引：1，自引：0，他引：1  

赵剑豪  陈振建  方家强 《岩土力学》2004,25(Z2):265-270

水泥搅拌桩--锚杆组合支护结构是一种新型的组合支护结构,笔者采用有限元方法进行各相关力学参数研究,分析了该组合支护结构的受力特性及变形性态.通过计算结果与实测数据的比较,表明本文所得结论对该组合支护结构的应用有一定的指导价值.  相似文献   

基于RS和GIS的农业土地利用污染分析   总被引：1，自引：0，他引：1  

姜馨  吴健平  石纯 《现代测绘》2004,27(3):12-14

农业已被确认为地表和地下水最主要的非点源污染源，而土地利用方式又是影响非点源污染的关键性因素。大规模的土地利用与开发、化肥与农药用量的增加、规模养殖业的发展、生活垃圾的增加等，这些非点污染源严重威胁水体质量，进而影响到人们的生活。为了更好地预测和控制、管理非点源污染，必须研究其负荷定量化问题。本文从以上几方面入手，讨论了非点源污染与农业土地利用方式之间的关系，利用组件GIS技术，以网格为评价单元，实现非点源污染负荷的定量计算及可视化分析。文章最后以上海市松江区作为研究区域，对该区的污染情况进行了分析。  相似文献   

华北活动地块区南缘阜南-霍邱地区地壳活动习性初探     

姚大全  刘加灿 《中国地震》2005,21(2):216-223

阜南-霍邱地区地处华北和华南活动地块区边缘构造带，通过对其进行地震地质调查和综合分析研究，发现晚更新世以来该区存在强度较弱的构造变形现象，即：小震沿着主要断裂呈线性条带状分布；研究区南部及断裂近侧的上更新统中发育共轭剪节理；1970年代，研究区固始、霍邱和阜南等地陆续发生过长度不一、宽窄不等、方向不同的地裂缝，展布与肥中断裂或王老人集断裂近乎一致。本文认为，研究区局部小震丛集、上更新统中赋存共轭剪节理、裂面充填物显微揉皱变形和现代地裂缝的生成等现象，反映出地壳能量被缓慢释放和相应断裂发生微弱活动；研究区曾发生过一次破坏性地震(江口集Ms43/4地震)。综上所述，研究区地壳晚第四纪以来具有微弱活动性，且主要表现为蠕滑活动方式。  相似文献   

A complex, Subplinian-type eruption from low-viscosity, phonolitic to tephri-phonolitic magma: the AD 472 (Pollena) eruption of Somma-Vesuvius, Italy     

Roberto Sulpizio  Daniela Mele  Pierfrancesco Dellino  Luigi La Volpe 《Bulletin of Volcanology》2005,67(8):743-767

The combined use of field investigation and laboratory analyses allowed the detailed stratigraphic reconstruction of the Pollena eruption (472 AD) of Somma-Vesuvius. Three main eruptive phases were recognized, related either to changes in the eruptive processes and/or to relative changes of melt composition. The eruption shows a pulsating behavior with deposition of pyroclastic fall beds and generation of dilute and dense pyroclastic density currents (PDC). The eruptive mechanisms and transportation dynamics were reconstructed for the whole eruption. Column heights were between 12 and 20 km, corresponding to mass discharge rates (MDR) of 7×10⁶ kg/s and 3.4×10⁷ kg/s. Eruptive dynamics were driven by magmatic fragmentation of a phono-tephritic to tephri-phonolitic magma during Phases I and II, whereas phreatomagmatic fragmentation dominated Phase III. Magma composition varies between phonolitic and tephritic-phonolitic, with melt viscosity likely not in excess of 10³ Pa s. The volume of the pyroclastic fall deposits, calculated by using of proximal isopachs, is 0.44 km³. This increases to 1.38 km³ if ash volumes are extrapolated on a log thickness vs. square root area diagram using one distal isopach and column height.Editorial responsibility: R Cioni  相似文献   

在卸荷产生拉剪情况下裂隙岩体的力学行为     

吴汉辉  杨转运  刘会 《岩土工程技术》2005,19(5):237-240

据岩体在卸荷情况下的拉剪应力状态,确定了节理岩体的线弹性断裂力学模型。依照此模型,可以得到相对远离裂隙(该位置的点到裂隙中心的距离比裂缝长度大)且受裂隙影响区域内应力、应变和变形方程。这些对评估裂隙岩石变形有重要的参考意义。通过用理论方程的计算结果和卸荷情况下试验观测所得的数据对比,证明该模型应用于实际工程中具有可行性。  相似文献   

The Effect of Machine Behaviour and Mechanical Properties of Intact Sandstone Under Static and Dynamic Uniaxial Cyclic Loading   总被引：5，自引：0，他引：5  

M. N. Bagde  V. Petroš 《Rock Mechanics and Rock Engineering》2005,38(1):59-67

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GPS monitoring of vertical ground motion in northern Ardenne–Eifel: five campaigns (1999–2003) of the HARD project     

A. Demoulin  J. Campbell  A. De. Wulf  A. Muls  R. Arnould  B. Görres  D. Fischer  T. Kötter  M. Brondeel  D. Van. Damme  J. M. Jacqmotte 《International Journal of Earth Sciences》2005,94(4):515-524

We present the HARD project of GPS monitoring of vertical ground motion in NE Ardenne and Eifel (western Europe). Its main purposes are to get a better insight into the present-day rates of vertical ground motion in intraplate settings and to identify the various causes of these motions. Since 1999, we have carried out yearly campaigns of simultaneous GPS measurements at 12 sites situated so as to sample the different tectonic subunits of the study area and especially to record potential displacements across the seismogenic Hockai fault zone. Five campaigns (1999–2003) have been processed currently. Key issues of the data processing with the Gamit software are discussed and first results are presented. Though temporally consistent in many cases, the obtained vertical motion rates are spatially highly variable. They are also much too high (several mm/year) to support a tectonic interpretation, and a long-term influence of groundwater level variations is proposed to account for the observed motions. This influence should be distinguished from seasonal variations and from inter-survey variations linked to the varying degree of soil and subsoil drying off during the successive spring surveys.  相似文献   

An approach to model the mechanical behavior of transversely isotropic materials          下载免费PDF全文

M. Mahjoub  A. Rouabhi  M. Tijani  S. Granet 《国际地质力学数值与分析法杂志》2016,40(6):942-961

The present work proposes an approach to adapt existing isotropic models to transversely isotropic materials. The main idea is to introduce equivalence relations between the real material and a fictitious isotropic one on which one can take all the advantages of the well‐established isotropic theory. Two applications of this approach are presented here: a failure criterion and a damage model that takes into account the load‐induced anisotropy. In both cases, theoretical predictions are in agreement with the experimental data. In the present paper, the developed approach is applied to sedimentary rock materials; nevertheless, it can be generalized to any material that exhibits transverse isotropy. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Semi‐analytical solution to one‐dimensional consolidation for unsaturated soils with semi‐permeable drainage boundary under time‐dependent loading          下载免费PDF全文

L. Wang  D. A. Sun  A. F. Qin  Y. F. Xu 《国际地质力学数值与分析法杂志》2017,41(16):1636-1655

This paper presents semi‐analytical solutions to Fredlund and Hasan's one‐dimensional consolidation of unsaturated soils with semi‐permeable drainage boundary under time‐dependent loadings. Two variables are introduced to transform two coupled governing equations of pore‐water and pore‐air pressures into an equivalent set of partial differential equations, which are easily solved by the Laplace transform. The pore‐water pressure, pore‐air pressure and settlement are obtained in the Laplace domain. Crump's method is adopted to perform the inverse Laplace transform in order to obtain semi‐analytical solutions in time domain. It is shown that the present solutions are more general and have a good agreement with the existing solutions from literatures. Furthermore, the current solutions can also be degenerated into conventional solutions to one‐dimensional consolidation of unsaturated soils with homogeneous boundaries. Finally, several numerical examples are provided to illustrate consolidation behavior of unsaturated soils under four types of time‐dependent loadings, including instantaneous loading, ramp loading, exponential loading and sinusoidal loading. Parametric studies are illustrated by variations of pore‐air pressure, pore‐water pressure and settlement at different values of the ratio of air–water permeability coefficient, depth and loading parameters. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献