Gustiness and coherent structure under weak wind period in atmospheric boundary layer

Statistical analysis of turbulent and gusty characteristics in the atmospheric boundary layer under weak wind period has been carried out.The data used in the analysis were from the multilevel ultrasonic anemometer-thermometers at 47 m,120 m,and 280 m levels on Beijing 325 m meteorological tower.The time series of 3D atmospheric velocity were analyzed by using conventional Fourier spectral analysis and decompose into three parts:basic mean flow(period > 10 min),gusty disturbances(1 min < period < 10 min)and turbulence fluctuations(period < 1 min).The results show that under weak mean wind condition:1)the gusty disturbances are the most strong fluctuations,contribute about 60% kinetic energy of eddy kinetic energy and 80% downward flux of momentum,although both the eddy kinetic energy and momentum transport are small in comparison with those in strong mean wind condition;2)the gusty wind disturbances are anisotropic;3)the gusty wind disturbances have obviously coherent structure,and their horizontal and vertical component are negatively correlated and make downward transport of momentum more effectively;4)the friction velocities related to turbulence and gusty wind are approximately constant with height in the surface layer.

Weak Interactions and 2D Layer Structure of a New Ion-pair Complex Bis(1-benzyl-4-methylquinolinium)-bis(maleonitriledithiolato)nickel(Ⅱ)

A new ion-pair complex, [BzMeQ1]2[Ni（nmt）2]1（[BzMeQ1]^＋ = 1-benzyl-4-ntethylquino- linium, mnta- -- maleonitriledithiolate） has been synthesized and structurally characterized by IR, ESI-MS and X-ray diffraction methods. Complex 1 is of triclinic, space group PI, with a = 9.079（2）, b = 10.154（2）, c = 11.243（2）A, α= 81.58（1）, β= 69.63（1）, γ = 68.02（1）°, V= 940.1（3）A3, Dc = 1.427 g/cm^3, Z = 1, F（000） = 418 and R = 0.0442. A 2D layer structure is formed via the cation-cation π…π and C-H…π interactions observed in the solid state of the complex.

Single-borehole measuring method for broken rock zone in gently inclined thin layer weakness structure

According to the structural characteristics of gently inclined thin layer rock mass in which lots of weak interlayer existed,the concept of gently inclined thin layer weakness structure was proposed.If single-borehole measuring method of the acoustic along the conventional arrangement mode was used in measuring the broken rock zone in this structure,the change of the relationship curves (Vp-L) between acoustic p-wave velocity (Vp) and borehole depth (L) would present the irregular feature due to the mechanical characteristics of layered rock mass and harmful effects of weak interlayers,and the scope of broken rock zone couldn't be defined quickly.Based on the analysis of the me- chanical characteristics of layered rock mass,the propagation rule of acoustic and distri- butions characteristics of plastic zone and slip zone in layered rock mass,new arrange- ment mode of acoustic measuring boreholes for broken rock zone in gently inclined thin layer weakness structure was proposed.Namely,the measuring boreholes in two sides were parallel to the strata,the measuring boreholes in the roof and floor perpendicular to the strata.Besides the controlling depth of the measuring boreholes in the scope of the large plastic zones or the large slip zones should be increased.Engineering example showed that new acoustic measuring boreholes arrangement mode had the better appli- cability and could determine the scope of the broken rock zone in the gently inclined thin layer weakness structure quickly.

ON THE EVOLUTION OF LARGE SCALE STRUCTURES IN THREE-DIMENSIONAL MIXING LAYERS

In this paper, several mathematical models for the large scale structures in some special kinds of mixing layers, which might be practically useful for enhancing the mixing, are proposed. First, the linear growth rate of the large scale structures in the mixing layers was calculated. Then, using the much improved weakly non-linear theory, combined with the energy method, the non-linear evolution of large scale structures in two special mixing layer configurations is calculated. One of the mixing lavers has equal magnitudes of the upstream velocity vectors, while the angles between the velocity vectors and the trailing edge were pi /2 - phi and pi /2 + phi, respectively. The other mixing layer was generated by a splitter-plate with a 45-degree-sweep trailing edge.

Numerical Analysis on the Seismic Performance of Plane Irregular Structure Based on ABAQUS

Rod element and shell element were used in finite element software ABAQUS to establish dynamic elastic-plastic analysis model of the structure,the seismic performance of an irregular plane complex overrun structure numerical simulation,the structure was calculated under different input level and displacement response of the acceleration response,and analyses the force of the wear layer column and the floor of the open hole stress level.The results were compared with the shaking table test to verify the accuracy of the numerical simulation results.The results of numerical calculation were basically consistent with the experimental results,and the finite element model basically reflected the response of the structure under the simulated earthquake.

A simple model for approximate bandgap structure calculation of all-solid photonic bandgap fibre based on an array of rings

A simple model for approximate bandgap structure calculation of all-solid photonic bandgap fibre based on an array of rings is proposed. In this model calculated are only the potential modes of a unit cell, which is a high-index ring in the low-index background for this fibre, rather than the whole cladding periodic structure based on Bloch＇s theorem to find the bandgap. Its accuracy is proved by comparing its results with the results obtained by using the accurate full-vector plane-wave method. High speed in computation is its great advantage over the other exact methods, because it only needs to find the roots of one-dimensional analytical expressions. And the results of this model, mode plots, offer an ideal environment to explore the basic properties of photonie bandgap clearly.

软弱结构面参数对顺层岩质边坡动力响应的影响研究

为了探究地震作用下软弱结构面对岩质边坡动力响应特征的影响。以云南省某露天矿山边坡为研究背景,利用有限差分软件中的非线性动力分析法对顺层岩质边坡进行动力计算,通过控制变量法设计了一系列的数值实验,探究了软弱结构面参数的改变对岩质边坡动力响应的影响规律,再基于正交试验以及极差分析法对影响岩质边坡动力响应的结构面参数进行了敏感性分析。结果表明:结构面参数的改变对于顺层边坡的动力响应有较大影响;各影响因子对顺层岩质边坡动力响应影响程度大小排序为结构面黏聚力>结构面倾角>结构面内摩擦角>结构面厚度。动力响应的研究可为地处地震频发区域的顺层岩质边坡提供抗震依据。

高应力断层构造区巷道冲击破坏特征研究

断层构造区静动载应力耦合作用加剧了井下断层区围岩冲击危险性,断层构造区巷道围岩应力分布规律及冲击动载响应特征存在显著特殊性。目前对于断层构造区的冲击研究主要集中于工作面采场附近,但对于断层构造区巷道冲击破坏鲜有研究。以陕西某矿深埋高应力断层构造区巷道为工程背景,分析了断层构造区巷道围岩变形破坏力学特征:①断层面存在明显应力阻隔效应,正断层附近存在上盘应力集中区和下盘应力降低区2个特殊应力区。巷道由于断层面影响,巷帮静载集中应力呈现非对称分布特征,远离断层面侧应力集中程度大于靠近断层面侧,该侧巷道围岩冲击破坏危险程度增大。②断层面对于应力波传递产生明显阻隔作用,正断层上盘动载响应大于下盘动载响应,由于巷道两帮应力非对称分布特征,右帮动载响应明显大于左帮。基于上述特征,提出了断层构造区巷道围岩“卸(大直径钻孔卸压)−支(梯次加固成层式吸能防冲支护)”协同防冲控制技术,工程试验结果表明:①巷道围岩采取“卸−支”协同防冲处理措施后,巷道两帮应力集中区往围岩深部转移3~5 m,应力峰值降低18.5%~20.3%,巷道帮部围岩应力集中程度显著降低。②采用“卸−支”协同防冲处理措施前,巷道顶底板及两帮变形量分别为856,334,325,567 mm,巷道围岩变形破坏严重,采用“卸−支”协同防冲处理措施后,巷道围岩变形量降低35.69%~62.03%,巷道围岩稳定性增强。③钻孔煤粉量显著低于临界粉煤量,巷道围岩动力显现降低。

厚胶层复合材料弱粘接结构的超声反射特性

开展了复合材料粘接结构粘接质量的非接触式超声反射特性的仿真与实验研究。首先,建立了水浸环境下纤维增强复合材料(FRP)单层板时域仿真模型,数值分析了不同入射角度下声反射系数频率谱的变化规律,并与已有理论方法进行了对比验证。基于此,建立了含厚胶层的复合材料粘接结构反射特性时域仿真模型,分析了粘接界面弱化程度对超声反射系数频谱特征点的影响规律。基于水浸超声反射特性测量系统,实验萃取了完好粘接状态的FRP粘接结构的超声反射系数频谱,与仿真结果吻合良好。随后,制备了具有不同粘接界面状态特征的FRP粘接结构试样,从实验角度揭示了单/双粘接界面弱化状态与超声反射特性间规律性的偏移特征。基于不同粘接状态与超声反射特性间的规律性分布特征,可为厚胶层复合材料粘接结构的粘接质量评估提供新的研究思路。

考虑割理面时煤层造斜段坍塌压力变化规律研究

在武威盆地太原组水平井钻进作业时,依据井史数据调研发现,煤层段卡钻、井径扩大、钻具掉落等井壁坍塌导致的井下复杂事故发生,严重制约了煤层气勘探开发的进程。由于煤岩交错割理性(面割理、端割理)弱结构面发育,使煤岩在造斜钻进时井壁破坏在力学上呈现为非连续性和非均质性。建立了考虑弱面的井壁坍塌数学模型。通过分析煤岩矿物成分、微宏观结构,确定煤岩井壁坍塌为力学机制占主导因素,得出割理导致的煤岩碎裂成块是井壁失稳的根本原因,建议在后续煤层钻井中优化井眼轨迹、优化钻井液性能进行井壁防塌,并引入煤岩井壁坍塌实时监测系统。

基于沉降控制和成本节约的CFG桩设计研究--以长白山紫玉漫江湾5号地建设项目一期酒店为例

临江漫滩场地条件下,地基土分布极其不均,地层物理力学性质差异较大,在此地基土上建造异型建筑,控制建筑的差异沉降是地基处理设计的重难点。文中结合“长白山紫玉漫江湾5号地建设项目一期酒店”项目,详细介绍了在漫滩地质条件下,设计采用CFG桩复合地基处理地基土,实现承载力、沉降满足设计要求,并节约大量造价的工程设计实例,对类似地层及结构荷载条件下进行CFG桩复合地基设计有很好的借鉴意义。

某平面不规则砌体建筑的加固设计与分析

某砌体办公楼建于20世纪80年代,存在明显缺陷:层数、高度超限;平面不规则;抗震措施多方面不足。该砌体结构整体性及抗震能力差,改造为幼儿园后设防类别调整为乙类,文章分析加固后整体结构的抗震性能。采用钢筋混凝土面层加固砌体墙,研究墙体受压、抗震、楼层综合抗震能力指数等指标,确保竖向构件在多遇地震下的安全性,提高整体结构抗震能力。综合考虑周围环境、施工周期、投入成本等因素,针对建筑改造内容与结构抗震措施缺陷,整理归纳一套加固对策。针对建筑的平面不规则缺陷,将加固后墙体换算等效成混凝土剪力墙,进行大震下静、动力弹塑性计算,以满足罕遇地震下的承载能力与变形要求,确保“三个水准”的抗震设防目标。

某堆填土欠稳定高边坡抗剪强度参数取值研究

梧州市某楼盘在建筑安全影响范围内有一削坡形成的高度20~45 m的堆填土高边坡,存在较大滑塌安全隐患,需对该欠稳定高边坡综合整治处理。为取得符合实际的、经济合理的边坡设计抗剪强度参数,采用了综合法确定抗剪强度参数,即采用现场原位直剪试验、室内重塑土样试验、多元线性回归法等,综合分析确定欠稳定高边坡的抗剪强度参数。结果表明:采用综合法参数取值能优化边坡设计、缩短治理工期、节约治理费用,治理效果显著。

某项目顺层边坡的稳定性计算分析与失稳预防处置

顺层边坡是山区公路建设中常见的一种不良地质,而且由于软弱结构层的存在,其具有比普通边坡更复杂的地质破坏模式,施工过程中在外力的扰动下极易发生失稳。因此,为了减少顺层边坡施工过程中的失稳破坏,提前对边坡采取了有效的预防措施,即:通过对已滑移段顺层边坡进行反演,计算得到了滑体结构面的相关参数;再根据计算所得结构面参数,模拟分析未滑移段顺层边坡的稳定性,确定了边坡支护所需的剩余下滑力;最后提出了针对性预防措施并加以实施,最终提高了边坡的稳定性。该方法能够在边坡发生较小范围破坏时,模拟获得稳定性参数,并对顺层边坡进行处理;同时可为相同地质条件的边坡防护提供参考,以避免更大范围的边坡失稳破坏,达到防患于未然的目的。

受控于软弱结构面的矿山软岩边坡稳定性

为了解决沉积岩体露天开采时的边坡稳定问题,根据岩体中软弱结构面的力学特性,分析总结了受软弱结构面控制的矿山软岩边坡稳定性的研究方法。探究了受控于软弱结构面的边坡的滑坡模式、计算方法以及强度指标的选取原则。对伊敏煤电公司露天矿南帮边坡稳定情况进行了实例分析,变形区边坡稳定性主要受四个泥岩弱层控制,采取内排压脚等控制开采的方法是有效的。

弱面控制蠕动边坡变形机制及滑坡控制技术

为寻求含软弱结构面的蠕动边坡稳定性控制因素及边坡失稳判据,为滑坡控制技术研究提供理论依据。对此类蠕动边坡变形力学系统模型进行了分析与讨论,结合各段的受力分析,得出此类边坡变形破坏的模式,为上部追踪节理、裂隙面形成准圆弧面,坡体在自重应力作用下,沿赋存有水平顺坡向或反坡向的缓倾软弱岩层蠕滑形成滑坡。此类滑坡控制应优先采用上部减重、下部压脚与边坡防排水工程相结合的综合治理方案。将此方案应用到安家岭露天矿北帮滑坡实例中,取得了良好的效果。

软弱结构面剪切蠕变特性与含水率关系研究

软弱结构面往往控制着岩体的蠕变变形,含水率又是影响软弱结构面蠕变特性的重要因素,通过开展不同含水率条件下砂岩软弱结构面剪切蠕变试验,得到了不同含水率条件下剪切蠕变曲线,并考虑加载历史对试验曲线进行了修正。在此基础上,通过模型辨识选取Burgers模型描述砂岩软弱结构面蠕变的黏弹性特性。分析了含水率对砂岩软弱结构面剪切蠕变特性的影响,并对含水率影响软弱结构面剪切蠕变特性的机制进行了探讨。

分配层分层结构对核爆炸荷载的防护效果试验研究

由于受经费和地质条件的限制,人防工程不可能无限制地增加防护层厚度,因此利用分层结构对爆炸波的衰减和弥散效应,通过试验研究分配层分层结构对核爆炸荷载的防护效果是十分必要的.利用平面装药爆炸模拟核爆炸的加载技术,进行了分配层分层结构对核爆炸荷载防护效果的大比尺相似模拟野外化爆试验,通过4个精心设计的不同分层结构的平面装药加载试验,证明了分配层分层结构对核爆炸的防护效果明显优于单层结构.

软弱结构面粒度成分与抗剪强度参数的关系探讨

软弱结构面一直是水电工程建设中的一个重要工程地质问题 ,选取合理的力学参数对大坝建基面的选取及未来坝基抗滑稳定性具有重大意义。本文在大量试验资料基础上 ,研究了沉积岩地区某重力坝电站坝址区软弱夹层粒度成分和抗剪强度参数之间的相关关系 ,建立了不同稠度状态下的相关方程。并结合《混凝土重力坝设计规范》中提出的用粒度成分定量指标选取软弱结构面抗剪强度参数 ,对软弱结构面抗剪强度参数取值问题进行了探讨。

堆积层-基岩接触面滑坡的形成机理——以祖师庙滑坡为例

为了研究堆积层-基岩接触面滑坡的形成机理,以陕西省岚皋县广泛分布的堆积层-基岩接触面滑坡为研究对象,采用野外调查和数理统计的方法,总结了该类型滑坡的基本特征,并以祖师庙滑坡为例,借助室内试验和数值模拟手段,研究了堆积层-基岩接触面滑坡的形成机理。结果表明:1)堆积层-基岩接触面滑坡主要发育在坡度为20°~40°、下伏基岩为碎裂状结构的斜坡,多为浅表层滑坡;2)碎石土和堆积层-基岩接触面的内摩擦角随含水量增大而降低,堆积层-基岩接触面是斜坡变形破坏的软弱结构面;3)细颗粒物质的增加降低了堆积层-基岩接触面的内摩擦角,且细颗粒粒径越小,内摩擦角也越小,在饱和状态下降幅度越大;4)因细颗粒物质在堆积层-基岩接触面处聚集造成的强度降低和因水文地质条件改变造成的滑带土饱和是祖师庙滑坡主要的诱发因素。研究结果对揭示堆积层-基岩接触面滑坡的形成机理和地质灾害防治具有一定的指导意义。