Numerical simulation of influence of the anomalies of theCentral-eastern Equatorial Pacific SST and Arctic seaice cover in summer on the atmospheric circulation

A series of numerical experiments have been conducted with a perpetual July, nine-level general circulation spectral model to determine the effect of variation of the Arctic sea ice cover extent and the joint effect of anomalies of both the Arctic sea ice cover and the Central-eastern Equatorial Pacific sea surface temperature on the summer general circulation. Results show that the two factors,anomalously large extent of the Arctic sea ice cover and anomalously warm sea surface temperature over the Central-eastern Equatorial Pacific Ocean, play substantially the equal role in the effect on the summer general circulation, and either of them can notably induce the atmospheric anomalies. The main dynamical processes determining the effect of the Arctic sea ice and the equatorial SST anomalies are associated with two leading teleconnection patterns, i. e. the Asia North/American and Eurasian patterns observed in atmosphere. The results presented in this paper again prove that the general circulation is fundamentally motivated by the non-uniform heating between the equator and the pole on the rotating earth.

Numerical simulation of enhancing coalbed methane recovery by injecting CO_2 with heat injection

The technology used to enhance coalbed methane(CBM) recovery by injecting CO_2(CO_2-ECBM) with heat, combining heat injection with CO_2 injection, is still in its infancy; therefore, theoretical studies of this CO_2-ECBM technology should be perused. First, the coupling equations of the di usion–adsorption–seepage–heat transfer fields of gas are established. The displacement processes under di erent pressures and temperatures are simulated by COMSOL. Finally, the displacement effects, a comparison of the CO_2 storage capacity with the CH_4 output and the e ective influencing radius of CO_2 injection are analyzed and discussed. The results show that(1) the displacement pressure and temperature are two key factors influencing the CH_4 output and the CO_2 storage capacity, and the increase in the CO_2 storage capacity is more sensitive to temperature and pressure than the CH_4 output.(2) The gas flow direction is from the injection hole to the discharge hole during the displacement process, and the regions with high velocity are concentrated at the injection hole and the discharge hole.(3) A reduction in the CH_4 concentration and an increase in the CO_2 concentration are obvious during the displacement process.(4) The e ective influencing radius of injecting CO_2 with heat increases with the increase in time and pressure. The relationship between the e ective influencing radius and the injection time of CO_2 has a power exponential function, and there is a linear relationship between the functional coe cient and the injection pressure of CO_2. This numerical simulation study on enhancing CBM recovery by injecting CO_2 with heat can further promote the implementation of CO_2-ECBM project in deep coal seams.

Sensitivity of warm-sector heavy precipitation to the impact of anthropogenic heating in South China

Previous studies have mostly focused on the effect of anthropogenic heating（AH） on air pollution events. However, few studies have investigated the impact of AH on the warm-sector precipitation over South China. By using the Weather Research and Forecasting model（WRF）coupled with an urban canopy model with appropriate AH release values, the warm-sector heavy rainfall event that occurred over the Pearl River Delta（PRD） during 8 May 2014 was investigated.The results show that the warm-sector precipitation of the PRD is sensitive to the impact of AH.By affecting the convection in the initiation of precipitation, AH can reduce the total precipitation of urban areas by approximately 10%. The possible mechanism by which AH influences the warm-sector heavy precipitation is described as follows： AH induced local convergence shifts towards the border of the PRD and intensified the convection and precipitation therein, by rearranging the thermal distributions of the flow field. In addition, AH changed the local convergence within the urban PRD areas, which was weakened by the homogenous urban thermal environment, and thereby decreased the total urban precipitation.

Comparison Between Computer Simulation of Transport and Diffusion of Cloud Seeding Material Within Stratiform Cloud and the NOAA-14 Satellite Cloud Track

A precipitation enhancement operation using an aircraft was conducted from 1415 to 1549 LST 14 March 2000 in Shaanxi Province. The NOAA-14 satellite data received at 1535 LST soon after the cloud seeding shows that a vivid cloud track appears on the satellite image. The length, average width and maximum width of the cloud track are 301 km, 8.3 and 11 km, respectively. Using a three-dimensional numerical model of transport and diffusion of seeding material within stratiform clouds, the spatial concentration distribution characteristics of seeding material at different times, especially at the satellite receiving time, are simulated. The model results at the satellite receiving time are compared with the features of the cloud track. The transported position of the cloud seeding material coincides with the position of the track. The width, shape and extent of diffusion of the cloud seeding material are similar to that of the cloud track. The spatial variation of width is consistent with that of the track. The simulated length of each segment of the seeding line accords with the length of every segment of the track. Each segment of the cloud track corresponds to the transport and diffusion of each segment of the seeding line. These results suggest that the cloud track is the direct physical reflection of cloud seeding at the cloud top. The comparison demonstrates that the numerical model of transport and diffusion can simulate the main characteristics of transport and diffusion of seeding material, and the simulated results are sound and trustworthy. The area, volume, vidth, depth, and lateral diffusive rate corresponding to concentrations 1, 4, and 10 L-1are simulated in order to understand the variations of influencing range.

Influence factors on the ground surface rupture zone induced by buried normal fault dislocation

The seismic disaster presents a zonal distribution along the fault strike.In this paper,rupture zone of ground surface soil caused by the uniform dislocation,inclined dislocation and warped dislocation of buried normal fault are studied by constituting a three-dimensional finite element model in Automatic Dynamic Incremental Nonlinear Analysis(ADINA).According to the critical value of surface rupture,the variational features and influencing factors of width and starting position of the"avoiding zone"in engineering construction are analyzed by using 96 model calculations.The main results are as follows:(1)Since the rupture zone of the ground surface soil from the point of mechanics is different from the"avoidance zone"from the point of engineering safety,the equivalent plastic strain and the total displacement ratio should be considered to evaluate the effect of the seismic ground movement on buildings.(2)During fault dislocation,plastic failure firstly occurred on the ground surface soil of the footwall side,and then the larger deformation gradually moved to the side of the hanging wall of the fault with the increase of fault displacement.(3)When the vertical displacement of buried fault reaches 3 m,the width of"avoiding zone"in engineering construction varies within the range of 10-90 m,which is most affected by the thickness of overlying soil and the dip angle of the fault.

Influence of Reservoir on Groundwater Environment in the Ecologically Fragile Area, Northwest of China

As the research proposed reservoirs after impact on the surrounding ecological fragile areas of groundwater level and scope, through the proposed reservoir area and its surrounding data collecting, hydrogeology survey and related test, for Modflow system simulation platform, through to the boundary conditions, initial conditions and source sink term and related hydrogeological parameters, the model identification and verification, The model of hydrogeological parameters in the study area is constructed. The simulation results show that the groundwater depth near the reservoir area will be higher than the critical value (1.8 m) of secondary salinization of soil. At the same time, according to the investigation and experiment, if the reservoir does not do seepage treatment, the water infiltration in the reservoir will aggravate the environmental hydrogeological problems in the ecologically fragile area.

Analysis on the Influence Factors of Directional Controlled Blasting Assisted by Water Jet

Directional expansion of blast-induced crack is always the common purpose for directional controlled blasting. As it has been demonstrated that slot which located at the side of blasthole can function as a guidance for blast energy, let the stress concentration at the direction of water jet slot. Therefore, it is meaningful to investigate the influence factors of directional controlled blasting with water jet assistance. In this paper, the influence on the guiding characteristics of the water jet slot during the propagation of blast-induced crack by the change of length-width of slot was simulated by ANSYS/LS-DYNA. The results indicate that if the distance from blasthole exceeds the limit, the influence on the guiding characteristics by the change length-width of the slot will get smaller and smaller, and when the width of water jet slot remains the same, the stress shows a monotonic increasing trend with the increase of the length of water jet slot, and the stress reaches its maximum value when the length-width of water jet slot is 0.075m×0.0070m. Moreover, based on stress wave theory and rock fracture theory, the influential mechanism for both the law of transmission of stress wave and of crack propagation by natural fracture and water jet slot were analyzed. The criteria for blast-induced crack propagation were established.

采动诱发断层活化响应机制特征研究

在煤矿开采过程中,采动引起的应力扰动是导致断层活化的关键因素,这种断层活化是煤矿安全开采面临的主要挑战之一。断层活化不仅易于诱发煤矿冲击地压、底板突水等地质灾害,而且对开采安全构成重大威胁。为分析采动效应下断层构造带的演化机制,通过Flac^(3D)数值模拟软件及相似材料模拟试验,建立采动条件下断层的应力-位移响应模型,进行相关研究。结果表明:开采过程中,扰动对于应力的影响作用要先比位移产生,且应力会出现峰值;当应力出现峰值,达到屈服极限后,扰动对于位移的影响作用逐渐显现;随着工作面不断推进,采动导致上覆岩层大面积垮落,致使上覆岩层与断层带贯通,并逐渐诱发断层带的活化现象;采动影响下,断层活化并不是一次性全阶段活化,而是由上部到下部的逐渐活化,其具有明显的空间性、阶段性特征。明确了断层活化的发生特征,能够有效提高对于断层活化间接引起的冲击地压、底板突水等一系列地质灾害事故的预警预防,对于煤矿安全高效开采生产具有重要意义。

稠油自乳化水驱开发规律

受原油性质的影响,稠油自乳化水驱开发与常规水驱开发不同,传统的稀油水驱理论不适用于稠油水驱开发。以中国某稠油自乳化水驱油藏流体参数为基础,通过室内实验和数值模拟,研究自乳化水驱开发规律,揭示自乳化水驱机理和主要影响因素。采用新的数值模拟方法揭示自乳化水驱的稳定驱替阶段为类“活塞式”驱油模式,开发全过程可分为4个阶段,即纯油阶段、过渡阶段、平台阶段和水油比快速上升阶段。渗透率级差和原油黏度是影响自乳化水驱含水率的主要因素,其次是渗透率和注水速度。

动态热条件下原油罐储维温过程主要影响因素分析

掌握原油罐储维温过程主要影响因素,对原油库实现节能降耗目的起重要作用。在建立动态热条件下含蜡原油罐储维温过程三维理论模型的基础上,提出了加热盘管空间结构、周向效应对罐内对流传热的影响,划分了内、外因素影响区以及过渡区域;采用多元非线性回归的方法,建立不同季节边界位置主控影响因素模型,定量表征了罐边界油温与内、外因素之间的作用机制。结果表明:罐内大涡结构受无加热盘管区域局部湍涡影响,导致大涡结构向无盘管区域发生偏移。罐底低温区域受盘管周向效应影响较大,罐顶边界油品受内外因素影响大,形成最大厚度1.79 m的外界环境影响区;罐壁受保温层影响,只形成了内部维温热流影响区;冬季罐底形成了0.13 m的外界土壤影响区。

Helmholtz型空化射流喷嘴结构优化数值模拟研究

目前Helmholtz型空化射流喷嘴结构尺寸偏大,不适用于空化射流洗井解堵作业,且与其相关研究缺乏对射流脉冲特性的评价。为此,利用CFD数值模拟方法探讨了结构参数对Helmholtz型空化射流喷嘴脉冲性能的影响规律,对该类型喷嘴的结构进行了优化。研究结果表明:在入口长度为5~15 mm时,空化射流脉冲特性和入口长度呈反比关系;在出口长度为5~10 mm时,空化射流的脉冲峰值和脉冲幅度与出口长度呈正比关系,脉冲频率基本不受影响;所得喷嘴最优结构尺寸为喷嘴入口直径2.5 mm,入口长度5.0 mm,谐振腔入口圆角1.0 mm,谐振腔直径10.0 mm,谐振腔长度2.0 mm,碰撞壁夹角60°,出口长度10.0 mm,出口直径3.0 mm。研究结果可为空化射流解堵技术中空化射流喷嘴结构优化设计提供理论参考。

基于数值的鲫鱼游泳能力影响参数分析

鱼类游泳行为机理及游泳能力的影响因素是目前鱼类仿生学研究的热点问题。本文选取鲹科游动模式(carangiform)的典型—鲫鱼(crucian carp)作为研究对象,采用数值模拟的方法,利用动网格技术结合用户自定义函数(UDF),围绕运动参数、鱼体体型及游泳环境(壁面边界),以仿生鲫鱼到达动态稳定的巡游速度这一过程衡量鲫鱼游泳能力,对鲫鱼游泳能力的影响开展研究。结果表明:当摆动频率在0.07~5.50 Hz之间,摆幅系数在0.03~0.06之间,随着鱼体摆动频率和摆动幅度的增大,仿生鲫鱼获得动态稳定巡游速度的时间逐渐缩短,且巡航游速相应增加。将不同厚长比、体长的鲫鱼经过量化处理后进行数值计算,研究结果表明:以相同的摆幅和摆频向前游动,厚长比与游泳速度呈负相关,当厚长比小于0.166,仿生鲫鱼可获得更快的游泳速度;体长方面,将仿生鱼的体长设置为L,仿生稚鱼可更快速地到达巡游阶段,但到达动态稳定的巡航游速较低,约为0.6L s^(–1),仿生幼鱼在加速阶段速度较快,巡游阶段与仿生成鱼的动态稳定巡航游速基本一致,约为1L s^(–1);鱼体在壁面附近游动所产生的壁面效应会导致游泳速度降低,且双侧壁面对仿生鲫鱼游泳速度的影响较单侧壁面更为显著,当鱼体距单侧壁面0.5L,距双侧壁面0.8L时将不受壁面的影响。本文的研究结果可为鱼类仿生学研究提供有益参考。

跳台雪板仿生点阵结构优化设计

通过借鉴自然界中毛竹的截面微观结构特征,设计了一种应用于跳台雪板内的仿生点阵结构,并基于响应面方法进行了优化设计。通过数值仿真模拟准静态压缩和三点弯曲实验,探究了仿生点阵结构的承载与抗弯性能。研究仿生点阵结构的单胞胞体壁厚、柱状结构的半径和壁厚3个几何参数对其力学性能的影响规律,并运用主次影响分析方法探究不同几何参数对力学性能的影响程度。建立了以比刚度、比弯曲刚度最大为目标,以单胞几何尺寸为约束的优化模型,并采用非支配排序遗传算法进行计算求解,得到Pareto前沿最优解,经数值仿真验证仿生点阵结构抗弯承载性能显著优于雪板内原始点阵格栅结构以及其余2种点阵格栅结构。研究结果对于跳台雪板内填充点阵格栅结构的仿生设计以及雪板整体力学性能的提升具有重要意义。

窄条带状背斜油藏边部注水开发产能影响因素

JY油田Y油藏为典型窄条带状背斜油藏,其储集层注入水极易沿河道中心方向突进,导致油井快速水淹,产量递减快;由于对水体大小、构造幅度、储集层物性等产能影响因素认识不清,此类油藏开发难度较大。针对上述问题,建立了窄条带状背斜油藏精细数值模型,通过对比论证提出了“边部注水+逐步转注”开发,并在此基础上开展了水体大小、构造幅度、储集层物性等参数对产能的影响研究。结果表明:“边部注水+逐步转注”开发不仅可以增大边水能量,使得井网双向受效,还可以有效延缓构造高部位油井的见水时间,大幅度降低油井含水率。另一方面,在考虑油藏构造特征的前提下,量化了不同影响因素下的产能特征,明确了水体大小、构造幅度、垂向渗透率与水平渗透率之比等参数的合理界限,论证了不同储集层物性下油藏面积的适应性。可为同类型油藏改善注水开发效果提供借鉴。

不同地层与平立面关系下盾构下穿对高铁的影响及地层分区

盾构下穿高铁基础设施工程出现地愈加频繁,但针对盾构下穿高铁基础设施工程引起的变形的规律研究仍较少且不系统,同时,盾构下穿对高铁基础设施影响的分区也缺少较为精细、成熟、实用的成果。依托下穿高铁路基、隧道案例,利用数值模拟开展系统性参数研究,结合正交试验与单因素变量分析,对盾构下穿高铁基础设施工程影响规律以及影响范围分区进行了研究。研究认为,设计下穿角度时,应充分考虑对高铁水平不平顺对主要影响区范围的影响,且将角度最好控制在40°以上;随着盾构与待穿隧道间净距增大,影响范围逐渐扩大,最大沉降、轨道高低不平顺、水平不平顺逐渐减小;随着地层越来越软弱,最大沉降逐渐增长,影响范围逐渐扩大;针对不同地层条件的高铁隧道、路基,分别给出了盾构与高铁基础设施之间的合理净距建议。为了便于工程中判断盾构下穿对高铁的影响范围,基于大量模拟结果,进行相近土层、埋深归并,提出了7种地层在5种埋深下的影响区划分,可为盾构下穿高铁工程提供参考。

硬岩顶板切顶留巷围岩变形分区补强控制研究

【目的】森达源煤矿传统的宽煤柱开采方式导致采掘接续紧张,并引发严重的围岩变形问题。切顶留巷技术可优化巷道支护条件,提高采煤效率,促进煤矿高效安全生产。【方法】以1号煤层的10101工作面为研究对象,运用FLAC 3D数值模拟软件,深入探究了切顶高度、切顶角度、注浆加固深度对巷道掘进、预裂切顶和切顶留巷过程中煤帮内部、采空区及顶板应力变形特性的影响。确定出最佳切顶留巷方案。在此基础上,进一步模拟分析工作面前后不同区域的围岩受力变形情况。提出回采工作面前方0~30 m内为超前补强区,采取“高预应力锚索+单体配合铰接顶梁”的联合支护。后方0~100 m内为滞后补强区,采用“工字钢+单体支柱”联合支护,同时对矸石帮实施注浆加固。通过工程应用验证了区分补强控制变形措施的有效性。【结果】结果显示:最佳切顶留巷方案为切顶高度6 m,切顶角度15°,矸石帮注浆深度1 m。此方案下,10101工作面的巷道顶底板的最终变形量为155 mm,两帮的为84 mm,均符合矿井使用要求,验证了切顶留巷技术具有良好效果。【结论】结果表明:切顶留巷技术能有效解决传统宽煤柱开采方式中存在的围岩变形问题。然而,该技术的实施受切顶高度、切顶角度和矸石帮注浆深度等因素的影响较大,需结合数值模拟和现场状况进行具体确定。总体上,切顶留巷技术和分区补强控制措施对围岩变形的控制效果显著,为类似条件下的煤矿开采提供了宝贵的经验借鉴,因而具有广阔的应用前景。

影响流量管流量系数的因素分析

对某航空发动机整机试验装置的流量管三维流场进行数值模拟,通过布置虚拟测点,建立流量管虚拟试验校准和测量的仿真方法,研究流量管流量系数获取方法、校准试验测试布局,分析来流雷诺数、壁面粗糙度、流量管圆度对流量系数的影响。结果表明,附面层位移厚度法和校准试验法获取的流量系数接近。在同一流向布置测量截面,流量系数随流量管内雷诺数的减小而减小,随流量管壁面粗糙度的增大而减小;低雷诺数工况下,流量系数对粗糙度变化不敏感。对于低雷诺数工况或者在流量管壁面粗糙度较大时,应采用附面层位移厚度法或校准试验法获取流量系数。流量系数对流量管圆度的变化不敏感,建议采用校准试验方法获得有变形的流量管的流量系数。尽量采用校准试验法获取流量管宽雷诺数范围的流量系数,采用实际测量工况下的雷诺数对应的流量系数,修正流量管测量数据,才可保证流量管测量精度。

页岩气井间压裂窜扰机理及影响规律

四川盆地南部地区(以下简称川南地区)页岩气水平井体积压裂改造过程中,受地质及工程等因素影响,水力裂缝易与单一方向大尺度天然裂缝沟通并过度扩展,从而诱导邻井压力快速上涨,最终导致压裂窜扰、套管变形等问题,直接影响页岩气单井产量。为此,针对川南地区页岩气储层压裂窜扰模式多样、机制认识不清以及防控效果有限等问题,建立了全耦合页岩气水平井压裂多簇同步扩展数值模拟模型,并阐明了不同类型压裂窜扰的影响规律,最后提出了有效治理压裂窜扰的方法。研究结果表明:①天然裂缝发育的储层中,水平井裂缝易沿单一方向大尺度天然裂缝优势条带扩展,直接或间接对邻井产生影响,造成其压力涨幅异常;②页岩气水平井通过避免在风险段压裂或降低改造强度在一定程度上可减轻压裂窜扰的影响;③压裂井附近存在衰竭邻井时,裂缝更易往邻井低应力区扩展产生压裂窜扰,窜扰程度与岩石孔隙弹性密切相关。结论认为,合理避开风险段射孔、控制压裂改造强度可有效降低页岩气水平井压裂窜扰的风险,该研究成果可为同类国内外页岩气区块页岩气水平井压裂开发提供技术指导。

南昌地铁地下多管线近邻地铁人行通道的施工影响分区

针对地下地铁人行通道暗挖施工对近邻多管线扰动影响问题,依托南昌地铁3号线邓埠站1号出入口人行通道暗挖工程,采用数值计算与理论分析相结合的方法,系统研究了通道暗挖施工扰动作用下近邻多管线的力学特性,总结关键因素对管线力学行为的影响规律,提出了通道暗挖下近邻密集管线影响分区计算方法与控制措施。结果表明:结合Peck曲线分布规律确定出以控制值的60%与20%作为强影响分区、弱影响分区、无影响分区的阈值;采用多元非线性函数进行拟合得出的线竖向位移与多因素的关系函数,对影响分区划分效果较好;建立的地铁隧道暗挖对近邻密集管线强弱影响分区方法,可通过有效的措施将密集管线强影响区转变为弱影响区和无影响区,进而保障施工安全。

盾构法施工近距离下穿既有隧道变形影响分析

为了解盾构法施工近距离下穿对既有隧道影响,依托于实际工程,通过midasGTSNX三维有限元软件仿真模拟新建隧道穿越既有隧道的施工过程,分析既有隧道和土层的变形规律、采用“上小下大”的注浆模式研究注浆压力以及管片环宽对地层变形的影响。研究结果表明:当盾构机开挖掌子面不断靠近既有隧道时,施工对既有隧道的影响不断增大,在下穿时影响最大,此区间的隧道沉降值最大,是穿越过程中最危险的地方,在背离后隧道沉降值逐渐减小;地层随注浆压力的增大,施工造成的周围地层变形减少,在地层沉降没有稳定之前,根据地面的沉降情况,可进行二次注浆;环宽设置值的过大或过小都会增大地表沉降值,选取管片环宽时,要综合具体工程条件、施工成本和施工技术等方面考虑。盾构法施工下穿时,上下重叠区间内既有隧道的变形量最大,需提前做出安全施工的预案,确保施工安全。