A generalized multi-field coupling approach and its application to stability and deformation control of a high slope

Human activities, such as blasting excavation, bolting, grouting and impounding of reservoirs, will lead to disturbances to rock masses and variations in their structural features and material properties. These engineering disturbances are important factors that would alter the natural evolutionary processes or change the multi-field interactions in the rock masses from their initial equilibrium states. The concept of generalized multi-field couplings was proposed by placing particular emphasis on the role of engineering disturbances in traditional multi-field couplings in rock masses. A mathematical model was then developed, in which the effects of engineering disturbances on the coupling-processes were described with changes in boundary conditions and evolutions in thermo-hydro-mechanical （THM） properties of the rocks. A parameter, d, which is similar to damage variables but has a broader physical meaning, was conceptually introduced to represent the degree of engineering disturbances and the couplings among the material properties. The effects of blasting excavation, bolting and grouting in rock engineering were illustrated with various field observations or theoretical results, on which the degree of disturbances and the variations in elastic moduli and permeabilities were particularly focused. The influences of excavation and groundwater drainage on the seepage flow and stability of the slopes were demonstrated with numerical simulations. The proposed approach was further employed to investigate the coupled hydro-mechanical responses of a high rock slope to excavation, bolting and impounding of the reservoir in the dam left abutment of Jinping I hydropower station. The impacts of engineering disturbances on the deformation and stability of the slope during construction and operation were demonstrated.

滑坡治理方案的计算机辅助设计系统(Slope-CAD)的开发与研究

本文简要地介绍了“滑坡治理方案的计算机辅助设计系统 (Slope- CAD version 1.0 )”总体框架、基本思路、基本操作步骤以及其主要功能。滑坡治理方案的计算机辅助设计系统 (Slope- CAD)采用面向对象的程序设计语言和交互式图形处理技术开发。该系统具有交互式建立滑坡体地质模型、对滑坡体进行自动条分、自动采集各条块稳定性计算时所需参数以及智能化配筋等特点。利用 Slope- CAD,可以轻易地完成从滑坡体地质模型的建立→滑坡体稳定性计算→治理方案设计整个工作流程。通过对多个滑坡实例检验结果表明 ,Slope- CAD具有建模简单 ,操作方便 ,集成化程度高 ,自动化和智能化程度高 ,分析计算结果可靠 ,输出设计图纸方便快捷等优点 ,具有较大的推广应用价值。

Non-inverting buck-boost DC-DC converter based on constant inductor current control

The hysteresis control combined with PWM control non-inverting buck-boost was proposed to improve the light load efficiency and power density.The constant inductor current control(CICC)was established to mitigate the dependence on the external components and device variation and make smooth transition between hysteresis control loop and pulse width modulation(PWM)control loop.The small signal model was deduced for the buck and boost operation mode.The inductor current slope control(ICSC)was proposed to implement the automatic mode transition between buck and boost mode in one switching cycle.The results show that the converter prototype has good dynamic response capability,achieving 94%efficiency and 95%peak efficiency at full 10 A load current.

浙江省山区输电线路塔位边坡变形破坏主要类型与防治建议

山区输电线路铁塔基础施工改变了塔位附近原始微地形、覆盖植被等环境地质条件,岩土体内部原有应力状态发生了变化,在各种自然营力作用下,每年在浙江省山区会发生一定数量塔位边坡的变形与破坏。根据影响因素、变形破坏机理分析,结合现场勘查及实际情况,划分为坍塌、滑坡、流坍等边坡变形破坏类型,经研究总结得出其主要发育特征,并提出了防治建议。

Impactless biped walking on a slope

Walking without impacts has been considered in dynamics as a motion/force control problem. In order to avoid impacts, an approach for both the specified motion of the biped and its ground reaction forces was presented yielding a combined motion and force control problem. As an application, a walker on a horizontal plane has been considered. In this paper, it is shown how the control of the ground reaction forces and the energy consumption depend on the gradient of a slope. The biped dynamics and the constraints within the biped system and on the ground are discussed. A motion control synthesis is developed using the inverse dynamics principle proven to be most efficient for human walking research, too. The impactless walking with controlled legs is illustrated by a seven-link biped. The ＂flying＂ biped has nine degrees of freedom, with six control inputs. During locomotion, the standing leg has three scleronomic constraints, and the trunk has three rheonomic constraints. However, there are three rheonomic constraints for the prescribed leg motion or three scleronomic constraints for reaction forces of the trailing leg, respectively. The nominal control action for impactless walking can be precomputed and stored. The model proposed allows the investigation of several problems： uphill and downhill walking, optimization of step length,stiction of the feet on the slope and many more. All these findings are also of interest in biomechanics. C 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi：10.1063/2.1301302]

From the new Austrian tunneling method to the geoengineering condition evaluation and dynamic controlling method

The new Austrian tunneling method （NATM） is widely applied in design and construction of underground engineering projects. When the type and distribution of unfavorable geological bodies （UGBs） associated with their influences on geoengineering are complicated or unfortunately are overlooked, we should pay more attentions to internal features of rocks grades IV and V （even in local but mostly controlling zones）. With increasing attentions to the characteristics, mechanism and influences of engineering construction-triggered geohazards, it is crucial to fully understand the disturbance of these geohazards on project construction. A reasonable determination method in construction procedure, i.e. the shape of working face, the type of engineering support and the choice of feasible procedure, should be considered in order to mitigate the construction-triggered geohazards. Due to their high sensitivity to groundwater and in-situ stress, various UGBs exhibit hysteretic nature and failure modes. To give a complete understanding on the internal causes, the emphasis on advanced comprehensive geological forecasting and overall reinforcement treatment is therefore of more practical significance. Compre- hensive evaluation of influential factors, identification of UGB, and measures of discontinuity dynamic controlling comprises the geoengineering condition evaluation and dynamic controlling method. In a case of a cut slope, the variations of UGBs and the impacts of key environmental factors are presented, where more severe construction-triggered geohazards emerged in construction stage than those predicted in design and field investigation stages. As a result, the weight ratios of different influential factors with respect to field investigation, design and construction are obtained.

Characteristics and Implication of Double-Circular Slope Break

The characteristics of slope break during depression stage in the Songliao Basin of NE China are analyzed. It is indicated that double flexure slope breaks extend in a circle across the basin.One is nominated the inner slope break,and the other is the external slope break. Under different regional stress field,the control

Digital close loop control system for current-programmed mode arc welding inverter

A small-signal model of current programmed mode pulse width modulation converter including the equivalent sampling effect is introduced and analyzed. In this model, an addition pole is brought out by the sampling effect in the current loop gain, and it affects dynamic bandwidth and stability of the inner current loop. By selecting the appropriate stability parameter which determines the additional pole and describes the degree of peaking in closed loop transfer function, a control model of current programmed full bridge arc welding inverter with maximum frequency bandwidth and stability can be obtained. Small and large amplitude pulse current outputs are employed in simulations and experiments and results validate the design method.

断层斜交岩质高边坡开挖变形特征及其治理效果评价--以陕南地区某岩质高边坡为例

为厘清断层斜交岩质高边坡开挖变形特性以及边坡治理后的时变特性,以陕南地区某断层斜交岩质高边坡为例,综合采用现场调查、数值模拟以及多点位移监测等方法分析断层斜交岩质高边坡破坏机制,归纳了断层斜交岩质高边坡的主要致灾因子,分析了边坡开挖过程中的变形特性,并探讨了边坡治理的时效性。结果表明:研究区域地形陡峭,受断层和坡脚开挖影响呈现出典型临空地形地貌,且受地质构造影响,出露岩体破碎程度较高,节理裂隙发育;基于数值仿真论证了断层斜交岩质高边坡采用“上部锚索锁固+中部坡体刷方+下部锚索和抗滑桩加固”方案治理的可行性,现场调查和监测数据结果表明边坡治理效果明显;断层处流土溶蚀效应明显,强降雨诱发岩质高边坡后缘断层附近平台发生塌陷,在断层和坡脚部位增设排水措施后坡体病害得到有效缓解,整体变形速率得到有效控制。研究成果对断层斜交岩质高边坡的治理及破坏机制分析具有参考意义。

塔里木盆地麦盖提斜坡罗探1井奥陶系断控岩溶新类型油气藏勘探突破及意义

塔里木盆地麦盖提斜坡罗探1井在奥陶系碳酸盐岩获得勘探新突破,是麦盖提斜坡奥陶系断控岩溶新类型油气藏的首次勘探突破,标志着斜坡区发现一个重要的战略接替领域。结合区域钻井、测井、地震等资料,开展罗探1等井分析化验资料的综合分析,对麦盖提斜坡奥陶系碳酸盐岩的成藏条件进行再认识。麦盖提斜坡奥陶系碳酸盐岩断控岩溶储层的形成主要与走滑断裂活动相关,是麦盖提斜坡三类主要成储模式之一;麦盖提斜坡目前已发现油气均来自寒武系玉尔吐斯组烃源岩,基底古构造控制了下寒武统的沉积和烃源岩的分布;斜坡区存在加里东期、海西期—印支期和喜马拉雅期3期油气充注成藏过程,烃源岩、古构造演化及通源断裂控制油气复式聚集成藏,断裂活动期次、断穿层系决定了油气富集层系与油气藏性质。麦盖提斜坡奥陶系走滑断裂十分发育,延伸距离累计可达1000km以上,控制了断控岩溶储层和油气藏的分布,平面上具有明显的分区特征,资源规模大、可部署性强,展示出巨大的勘探潜力,是塔西南地区规模油气勘探发现和战略接替的重要现实领域。

水-气耦合下的土质边坡稳定系数场分析

传统边坡稳定性分析方法仅对潜在滑动面进行整体稳定性评估,无法获取各点的安全系数.基于稳定系数场理论,综合考虑水-气耦合作用,对降雨条件下边坡稳定性进行分析.结果表明:1)稳定系数场法能够直观地体现水-气耦合作用下边坡的具体破坏区域,得到各点的安全系数;2)孔隙气压力对边坡降雨入渗有一定阻碍作用,并且随着降雨时间的推移阻渗效果愈明显,相同条件下降雨40 h时,两相流湿润锋深度较单向流减小了28.6%;3)相同条件下,考虑水-气耦合作用将降低边坡稳定性,以降雨40 h为例,两相流边坡失稳面积约为单向流的1.7倍.因此,在实际工程中对边坡稳定性分析时考虑水-气耦合作用,工程偏于安全.

风电机组自适应步进惯量控制策略

若风电机组参与调频时采用步进惯量控制(stepwise inertial control,SIC)策略,其退出调频时有功快速下降可能会引发系统频率二次跌落(frequency second drop,FSD)问题。已有文献中一类改进的SIC策略通过减小风电机组退出调频后有功下降阶段的斜率来应对FSD问题,然而该类改进的SIC策略使得风电机组在退出调频后其有功需要一段时间才会小于风能捕获,在此期间转子转速会继续下降并有可能低于转速下限,危及风电机组运行安全。文章对这一类改进的SIC策略做了进一步完善,提出了一种风电机组自适应SIC策略,根据风电机组退出调频时的转子转速自适应设置风电机组退出调频后有功下降阶段的斜率,在确保风电机组退出调频后转子转速不会低于转速下限的前提下,最小化FSD的幅度。

露天地下楔形转接过渡诱导冒落控制边坡岩移危害技术研究

露天地下楔形转接过渡模式的安全管控是利用崩落法开采挂帮矿形成的塌陷坑阻止边坡岩移威胁露天采场,但地采扰动下的高陡边坡破坏过程不易控制,因而制约了楔形转接过渡模式在大型深凹露天矿山中的应用。针对上述问题,结合极限平衡分析方法,揭示出崩落法开采扰动下的高陡边坡渐进破坏规律,提出了边坡滑移体体积计算方法,以及通过调控回采顺序控制边坡滑移进程以实现塌陷坑完全承接边坡滑移体的边坡岩移危害控制技术。研究表明:边坡岩体不会随挂帮矿向下开采而发生持续破坏,只有当挂帮矿开采至关键分段时,边坡岩体受力状态超过极限平衡状态才发生滑移破坏,可通过滞后回采关键分段上盘三角矿延缓边坡滑移,以及通过滞后回采关键分段下盘矿体和采用下向阶梯状回采工作面增大塌陷坑容积,最终实现塌陷坑有序承接边坡滑移体。研究成果完善了大型深凹露天矿楔形转接过渡的安全管控方法,提高了楔形转接过渡模式的适用性。

昆明长水国际机场T2航站楼结构设计关键问题探讨

昆明长水国际机场T2航站楼面临高填方边坡、高抗震设防烈度、高铁下穿等多项复杂条件,给结构设计带来诸多挑战。在简单介绍T2航站楼结构体系基础上,从场地、隔震、振动控制和钢屋盖等四个方面对结构设计的关键问题进行了探讨,并给出了解决问题的途径。得出如下结论:复杂场地条件下的地震动参数应通过三维建模条件下的场地地震反应分析确定;高填方边坡在地震下的稳定性应结合拟静力法和时程分析法进行分析;不等标高基底隔震时,隔震层层间位移角限值应以控制罕遇地震下的支座变形为目标来确定;超长结构隔震应采取措施缓解混凝土收缩和温度效应对隔震支座变形的影响;混合使用不同竖向频率的隔振支座解决高铁运行导致的结构振动是可行的;树形柱分枝角度对柱的受力效率影响明显;与大跨屋盖相连的单索幕墙结构可通过自平衡方式减小索拉力对屋盖的作用。

较大纵坡浅覆土大断面矩形顶管顶进控制技术

以杭州地铁3号线支线留下站A1-A2出入口连接通道为背景,结合工程地质情况,介绍了始发井及接收井端头加固、较大纵坡及覆土较浅顶进控制等施工技术,对顶管变形和地表沉降监测结果进行了详细分析,阐述了顶管施工引起的周边土体变形特征。现场监测结果表明,采用有效、综合的顶管施工控制措施,避免了顶管下穿范围内的地面沉降问题。

斜坡限制域对脱体火焰宏观形状和燃烧振荡影响实验研究

燃烧振荡是贫油预混火焰中广泛存在的非定常过程,是燃烧室设计中必须避免的。其中,脱体火焰对降低氮氧化物排放有优势,但其燃烧振荡往往更加严重。本文在中心分级燃烧器中,通过实验方法研究了斜坡限制域对脱体火焰燃烧振荡的被动控制效果。本文通过单反相机和高速摄像获取了火焰平均结构和瞬态图像,并通过相平均图像和本征正交分解研究了火焰动态演变过程。结果表明,当台阶高度为0 mm时,不同斜坡张角的斜坡限制域均能对燃烧振荡起到非常显著的抑制效果。而在30°斜坡张角的斜坡限制域中,随着台阶高度的增加,抑制效果变差,但振幅相较突扩限制域发生了明显的降低。

黄河下游多因素耦合作用生态护坡破坏机制研究进展

黄河流域在中国经济社会发展中具有重要的战略地位,其下游河道水少沙多、水沙关系不协调,具有二级悬河、河势演变复杂等特点,岸坡破坏会严重威胁防洪安全和经济社会高质量发展,因此,保障岸坡稳定、开展黄河下游护坡治理与风险管控十分必要。生态护坡破坏涉及水、土、植被、结构等因素,机理复杂,传统河流动力学理论已不能完全适用,需进一步深入研究。本文总结分析了黄河下游岸坡破坏现状、岸坡失稳机理及其主要影响因素、生态护坡结构研究及应用和护坡工程风险评估及管控等方面现有研究成果及存在的不足,在此基础上探讨和梳理了黄河下游生态护坡未来的一些研究方向,包括揭示水-土-植被等多因素耦合作用下的生态护坡破坏机制、研发适用于强冲积特点的刚-柔协同新型生态护坡结构型式、建立考虑多要素多层次的生态护坡工程风险综合评价指标体系、形成岸坡监测-评估-处置/防护一体化的风险管控技术体系等。

高切岭段膨胀性土渠坡勘察与稳定性分析

江淮分水岭高切岭段渠道因特殊的地形地貌条件,且渠坡揭露地层具膨胀性,历年来屡次发生失稳现象。通过分析膨胀土渠道滑坡的特点和成因,选取典型断面,采用连续取样钻探和静力触探进行勘测,分析边坡滑动带或潜在滑动带的分布位置、发育特点和力学特性。考虑滑动带或潜在滑动带,分别对边坡实施阻滑措施,并进行稳定性验算。通过对渠坡的稳定性和阻滑处理措施的研究,为膨胀土边坡的阻滑防治提供参考。

基于BCD工艺的LIN总线收发器设计

针对汽车内部复杂的控制节点与严苛的通讯环境,设计了一款抑制电磁干扰的局域互联网络(Local interconnect network, LIN)总线收发器芯片。基于90 nm BCD高压工艺,采用双向静电放电保护、分段电流驱动、共源级隔离驱动以及总线反馈技术提高系统可靠性。测试结果表明芯片性能符合LIN总线物理层协议规范要求,实现了高低电压域的转换;同时具有良好的抗干扰能力,信号占空比最大变化仅为2.8%,电磁辐射比标准限制值低28 dBμV,达到车用LIN总线通讯相关标准要求。

多弱层顺倾软岩边坡控制开采技术

针对多弱层顺倾软岩边坡下部压煤问题,从边坡变形风险可控以及资源回收最大化角度出发,在分析地质资料和弱层层位的基础上,结合单一弱层的控制开采技术,提出了多弱层顺倾软岩边坡控制开采技术;以扎尼河露天矿北端帮边坡为工程背景,基于极限平衡理论,分析了北端帮边坡的稳定性,对多弱层控制的顺倾软岩边坡控制开采方案进行了研究。研究表明:通过多弱层顺倾软岩边坡控制开采技术的实施,可在采场深部增加内排物料形成“中间桥”工艺,对深部弱层形成“压覆”,对整体边坡形成“支撑”,保证边坡沿各弱层滑动均得以控制,实现多弱层顺倾软岩边坡煤炭高效回收以及蠕动形变的稳定性控制。