Finite element analysis of slope stability by expanding the mobilized principal stress Mohr's circles-Development, encoding and validation

In recent years,finite element analysis is increasingly being proposed in slope stability problems as a competitive method to traditional limit equilibrium methods(LEMs)which are known for their inherent deficiencies.However,the application of finite element method(FEM)to slope stability as a strength reduction method(SRM)or as finite element limit analysis(FELA)is not always a success for the drawbacks that characterize both methods.To increase the performance of finite element analysis in this problem,a new approach is proposed in this paper.It consists in gradually expanding the mobilized stress Mohr’s circles until the soil failure occurs according to a prescribed non-convergence criterion.The present approach called stress deviator increasing method(SDIM)is considered rigorous for three main reasons.Firstly,it preserves the definition of the factor of safety(FOS)as the ratio of soil shear strength to the mobilized shear stress.Secondly,it maintains the progressive development of shear stress resulting from the increase in the principal stress deviator on the same plane,on which the shear strength takes place.Thirdly,by introducing the concept of equivalent stress loading,the resulting trial stresses are checked against the violation of the actual yield criterion formed with the real strength parameters rather than those reduced by a trial factor.The new numerical procedure was encoded in a Fortran computer code called S^(4)DINA and verified by several examples.Comparisons with other numerical methods such as the SRM,gravity increasing method(GIM)or even FELA by assessing both the FOS and contours of equivalent plastic strains showed promising results.

On the Reconstruction of Teachers’Role of Business English Reading Classroom Teaching Based on Literature Circle

Business English reading teaching under the mode of“literature circles”focuses on cultivating students’autonomy in reading,group cooperation,and the exchange of ideas among group members.In this teaching mode,teachers are no longer the masters of the reading classroom,but the helpers,participants,and researchers in the process of students’reading.The reconstruction of teachers’role can promote the benign development of relationship not only between teachers and students,but also between students and students,inject new impetus and vitality into the classroom,and improve students’reading literacy.

A Procedure for the Squaring of a Circle (of Any Radius)

This paper presents a graphical procedure for the squaring of a circle of any radius. This procedure, which is based on a novel application of the involute profile, when applied to a circle of arbitrary radius (using only an unmarked ruler and a compass), produced a square equal in area to the given circle, which is 50 cm2. This result was a clear demonstration that not only is the construction valid for the squaring of a circle of any radius, but it is also capable of achieving absolute results (independent of the number pi (π), in a finite number of steps), when carried out with precision.

On the Construction of Mohr Stress Circle and a Graphic Method in Representing the Stress Components on Different Oblique Planes

The Mohr stress circle for three-dimensional stress is usually determined by equations,which is lack of intuitionistic meanings and difficult to understand. In this paper, the construction of Mohr stress circle is illustrated directly by numerical method. The shortcoming of Mohr stress circle in representing the stress components on different oblique planes for three-dimensional stress is analyzed. A three-dimensional figure is given to describe the variation of normal and shear stress on different oblique planes at one point for the first time.

Circle of Willis atherosclerosis, Alzheimer's disease and the Dean number

The important role of atherosclerosis in pathophysiology of Alzheimer's Disease has become evident.Mechanisms such as hyperlipidemia,inflammation,abdominal obesity and insulin resistance are important yet they may not fully explain the specific involvement of the Circle of Willis in these pathologies.The Circle of Wills is a complex geometrical structure which has several areas with different curvature as well as various branching angles of vessels composing the circle.The hemodynamics in this region should take into account the Dean number which indicates the influence of curvature on the resistance to blood flow.Thus,areas with various curvature and angles may have different hemodynamics and there are certain areas in the Circle of Willis that are more likely to develop atherosclerotic changes.Therefore,this could suggest the novel pathophysiological pathway resulting from the geometric peculiarities of the Circle of Willis.One of the directions of future research is to examine whether specific areas of the Circle of Willis are more likely to develop atherosclerotic changes compared to other ones.Selective areas of the Circle of Willis affected by atherosclerotic changes could indicate the primary role of atherosclerosis promoting Alzheimer's disease although other pathophysiological mechanisms suggesting the opposite direction should be also examined in prospective studies.

GRAPHICAL COMPUTING METHOD ON FOUR-BAR LINKAGE(1)——Inflexion Circle,Focal Axis,Ball's Point,Centering-point Curve and Circling-point Curve For Four ISPs,Coupler Curves Based on Ball's Points——

By means of programs GTMPAC based- on generalized triangle method,analysis and synthesis of mechanism design in accordance with absolutely graphicalmethod( absolutely germetrical method) are developed.In this paper,we make aspecial study about centering- point curve and circling- point curve and couplercurves based on Ball’s points.

Stability analysis of the simplest Takagi-Sugeno fuzzy control system using circle criterion

A frequency-domain-based sufficient condition is derived to guarantee the globally asymptotic stability of the simplest Takagi-Sugeno （T-S） fuzzy control system by using the circle criterion. The analysis is performed in the frequency domain, and hence the condition is of great significance when the frequency-response method, which is widely used in the linear control theory and practice, is employed to synthesize the simplest T-S fuzzy controller. Besides, this sufficient condition is featured by a graphical interpretation, which makes the condition straightforward to be used. Comparisons are drawn between the performance of the simplest T-S fuzzy controller and that of the linear compensator. Two numerical examples are presented to demonstrate how this sufficient condition can be applied to both stable and unstable plants.

Research on the Contribution of the Chinese People’s Political Consultative Conference in Promoting the Construction of the Chengdu- Chongqing Economic Circle

The influence applied by the Chinese People’s Political Consultative Conference(CPPCC)in promoting the construction of the Chengdu-Chongqing economic circle cannot be ignored.At present,the Sichuan Committee of CPPCC and Chongqing Committee of CPPCC are actively participating in the construction of the Chengdu-Chongqing economic circle by building collaborative platforms,conducting joint consultations,and holding consultations on special issues.From three aspects,namely the unique advantages of the CPPCC,the fact that full consultation between CPPCCs in different regions is conducive to coordinating the interests of local governments of the same level,and that fact that it is also conducive to promoting inter-governmental cooperation,this article elaborates on the necessity of the contribution of the CPPCC in promoting the construction of the Chengdu-Chongqing economic circle and discusses four paths for the CPPCC’s promotion of the construction of the Chengdu-Chongqing economic circle:Strengthening the Communist Party of China’s leadership over the political consultation work of the CPPCC,using the CPPCC to consolidate the consensus of“a Sichuan-Chongqing close family,”innovating the form,content,and objects of democratic supervision,and building the information exchange mechanisms between the CPPCCs of Sichuan and Chongqing.

About Circle’s Measurements——关于圆的度量

石子入水后浑然天成的圆形波纹,天体运行时近似圆形的轨迹,清晨冉冉升起的朝阳,遥远天际悬挂的那轮明月……圆,在生活中无处不在。

A Method for the Squaring of a Circle

This paper presents a Method for the squaring of a circle (i.e., constructing a square having an area equal to that of a given circle). The construction, when applied to a given circle having an area of 12.7 cm2, it produced a square having an area of 12.7 cm2, using only an unmarked ruler and a compass. This result was a clear demonstration that not only is the construction valid for the squaring of a circle but also for achieving absolute results (independent of the number pi (π) and in a finite number of steps) when carried out with precision.

基于小波变换的2018年永清M_(S) 4.3地震前易县地震台形变观测数据分析

2018年2月12日河北省廊坊市永清县发生M_(S) 4.3地震,易县地震台形变观测数据出现异常变化。选取2017年6月—2018年2月易县地震台DSQ型水管仪和VP型宽频带垂直摆EW向数据记录,采用db4小波变换方法进行分析,结果发现:水管仪EW向小波分解的第6和第7阶细节存在周期为64—256 h的信号,垂直摆EW向小波分解的第5、6、7阶细节中存在周期为32—256 h的信号,均偏离正常动态背景,不属于自然环境干扰,应为河西务断裂正断性质的破裂所致。

Fragmentation and Wholeness in Virginia Woolf’s The Waves

Virginia Woolf’s seventh novel,The Waves,first published by the Hogarth Press in 1931,is widely regarded as her most experimental piece of writing.The complex and elusive structure of the work,the least representational among Woolf’s novels,challenges the reader’s assumptions about the inner and the outer world.In the absence of a substantial story,of a convincing plot and well-defined characters,the reader is called upon to search for a deeper coherence and more profound meanings.Indeed,in The Waves the modernist writer strives for a fresh way of expressing a vision of wholeness in a broken world.The present article attempts to reread Woolf’s self-conscious novel in the double perspective of separation and reunion,of dispersal and recomposition.A close reading of selected passages will show how the poetics of fragmentation and the poetics of wholeness coexist in Woolf’s narrative,pervading the imagery and the symbols of the text.In more than one sense,the dialectic between division and unity,fragmentation and wholeness can be identified as the structuring force of the novel;most tellingly,this textual dynamism is reflected in the oscillatory motion of the waves,continuously breaking and merging.

泸州地区深层页岩气水平井套变成因机理探讨

四川盆地南部泸州地区深层页岩气储量丰富,是继长宁、威远等中浅层页岩气之后重要的天然气资源接替领域。但在泸州地区深层页岩气开发过程中水平井套管变形(以下简称套变)频发,对水平井压裂施工产生明显影响,制约了该区深层页岩气的规模建产。业内普遍认为套管变形是地层中的断裂发生滑移并对水平井产生剪切和挤压作用引起的,但基于该理论的套变模型与诸多实测数据不相吻合。为了进一步明确套管变形机理,提高套变的防控效果,以泸203井区18口套管变形水平井为对象,基于多臂井径成像测井,逐个对比套变形态、套变层位以及平面断裂发育情况,建立了断裂滑移和层理面滑移2种地质模型,并分析了2种地质模型下的不同套管变形特征。研究结果表明:(1)断裂滑移诱发的套变具有以下规律,即平面上套变仅出现在水平井与断裂带的交会处;套管的变形长度理论上应在10 m以内;套管的变形程度应呈近似对称关系,中部变形强,向两侧逐渐减弱。(2)该区多数套变不在预测的断裂带内,且部分套变段变形长度与形态不符合断裂滑移的特征。(3)层理面滑移可诱发多个相似的套变,在该机制下套管变形长度等于井筒与滑移面相交的距离,且层理面滑移的垂向分布与地层的页理发育程度一致。(4)层理面滑移与断裂滑移具有相似的力学机理,通过三维莫尔圆可以分析钻井和压裂过程中诱发断裂/层理面滑移的关键参数变化。结论认为,除断裂滑移外,层理面滑移是诱发页岩气水平井套管变形的另一重要机理,该研究成果可为深层页岩气规模效益开发的套变防控提供理论指导。

张量CSAMT数据处理技术初步研究与示范应用

面对大深度和三维探测,标量CSAMT(controlled source audio-frequency magnetotellurics)已显力不从心,而张量CSAMT正逐渐成为研究热点。在前人研究基础上,笔者就张量CSAMT数据处理方面提出Mohr圆分析和传统坐标旋转两种处理技术,并首次创新性地使用我国自主研发的综合电法仪开展了张量CSAMT示范应用。结果表明:Mohr圆分析和传统坐标旋转法相结合应用效果良好,可定性挖掘地下地质体的纵向和横向构造特征,主轴方位的视电阻率和阻抗相位与目标体对应良好,并且电阻率反演结果与钻孔等地质资料综合分析对建立试验区的地质地球物理模型是有益的。

大地电磁阻抗张量不变量及其Mohr圆分析

论述了Ｍｏｈｒ圆及其在大地电磁阻抗张量分析中的应用。并指出，大地电磁阻抗张量不变量由于提供信息的多样性和稳定性，在应用中具有独特的优点，而Ｍｏｈｒ圆又将各种大地电磁阻抗张量不变量有机地联系在一起，使其成为分析研究大地电磁阻抗张量性质的重要图示工具，能直观、清晰、简便地给出构造维数、二维偏离度、各向异性等重要信息，可用来研究测区电性结构沿纵向和横向的变化特征。

区域三维大地电磁阻抗张量畸变效应的Mohr圆分析

根据二维大地电磁阻抗张量分解原理，推导出剪切、扭曲和各向异性因素影响区域性三维响应的关系式。这既适用于任意复杂的三维构造，也包含了二维和一维情况。并用Ｍｏｈｒ圆分析了受畸变因素影响时的三维响应及其在微弱畸变与强烈畸变影响下不同的性质和特征。

基于S变换的新型波阻抗方向继电器

为提高行波保护的灵敏性与可靠性,提出一种基于S变换的新型波阻抗方向继电器。通过对正方向线路故障后初始行波特征的分析,定义方向继电器的背侧母线波阻抗。依据该阻抗及继电器正方线路波阻抗分别设置正、反方向阻抗圆,构成双阻抗圆的方向判据。利用S变换提取单频率的电压、电流初始行波,并计算出波阻抗,根据该阻抗在正、反方向阻抗圆内的位置判别故障方向。PSCAD/EMTDC仿真结果表明:该继电器能可靠、灵敏、超高速识别正反方向故障,其性能受故障初始角、故障距离、故障电阻等因素的影响小,能适应母线结构的变化。以该继电器构成的超高速方向纵联保护具有良好的工程应用前景。

基于岩石力学的井周裂缝流体疏导性分析与产能评价

电成像测井技术与偶极横波远探测技术可以有效识别井周裂缝。对于裂缝性油气藏,由于裂缝作为油气主要的储集空间与渗流通道,因此对识别的井周裂缝进行流体疏导性能评价对于油田实际生产具有重要意义。利用岩石力学中的三维应力莫尔圆对地应力作用下从井壁延伸至储层的裂缝进行应力状态分析,并结合莫尔库仑破裂准则进行裂缝临界应力状态判别,进而评价整体的流体疏导性能。数值模拟结果表明,除地应力大小外,不同断层类型的地应力状态和孔隙压力大小也决定着裂缝的临界应力状态。根据裂缝面应力状态求取裂缝的摩擦系数并进行校正可以定量反映裂缝的流体疏导性能,将裂缝发育层段内校正后的裂缝摩擦系数加权于裂缝密度,可实现目标井段流体疏导性能定量评价并为产能评价提供可靠依据。在渤中19-6裂缝性潜山凝析气田的应用实例表明,该方法可以有效地分析井周裂缝的流体疏导性能,实现不同裂缝对于产能贡献的定量评价,评价结果与地层实际测试产能结果有较好的相关性,为现场试油与开采方案的制定提供有效指导。

三向应力Mohr圆的真实构成及剪应力作用方向的确定

三向应力Mohr圆的构成在传统上是借助公式推证而得,并以平面图形来表示,缺乏三维的真实感和直观性。在应力应变分析中,对于平面应力问题,可以通过平面应力摩尔圆确定过一点不同斜面上的应力分量及其作用方向。对于三维问题,利用摩尔圆图解法可以确定某一斜面上的正应力和剪应力的数值,但不能表示剪应力的作用方向。剪应力的作用方向需要通过另外的图解方法来确定。本文分别从坐标系旋转和数值计算的角度解释了三向应力Mohr圆的构成过程,形象地说明了Mohr圆的物理本质。针对三向应力Mohr国不能表示剪应力作用方向的问题,通过矢量运算,给出了剪应力作用方向的确定公式。