平原地区公路路基的合理填土高度

通过对平原地区公路路基最小填土高度、不同等级道路要求路基填土高度、经济和景观协调及行车安全对路基填土高度的影响分析,提出了确定平原地区公路路基合理填上高度的方法,以完善平原地区公路路基设计。     

软土地基上路堤沉降变形特征分析

在软土地基上修筑高速公路 ,不同地基处理方法、不同填土高度下 ,硬壳层和软土层厚度对路基沉降的影响不同。通过对某高速公路采用粉喷桩和砂垫层预压法两种方法加固软基后 ,路基填筑过程中实测路堤沉降资料的深入分析 ,总结出在该地区硬壳层和软土层厚度对路堤沉降变形的影响规律 ,并提出了相应的填土临界高度 (约 2 .5m)。     

基于FLAC 3D的黄土地区路基拓宽变形数值分析

为研究路基加宽时其变形稳定性问题，研究以山西省朔州市南环路改扩建工程为例，通过有限差分数值模拟和理论分析等方法，对黄土地区新老路基拓宽工程的差异沉降特性进行了分析。结果表明：新旧路基的沉降和水平位移与加宽路基的填土高度呈正相关，随着填筑高度的增加，新旧路基坡脚处水平位移也逐渐增大，但水平位移最大值却在地表下2 m处出现。     

高海拔多年冻土地区宽幅沥青路面-路基体系#br# 热效应实测分析

为明确中低纬度高海拔多年冻土区“宽厚黑”路面结构和路面类型对路基路面体系温度场的影响规律,在青藏高原高温多年冻土区分别铺筑了窄幅和宽幅沥青路面-路基温度场监测试验段,对两种尺度路基路面体系不同深度和横向位置处以及天然大地不同深度处温度状况进行3年连续观测和统计分析。结果表明：宽幅路面沥青层年温度波动幅度高于窄幅路面,且波动幅度差异随路面结构层深度增加而减小;新建公路路基填土会经历持续2年以上的初期冻融放吸热不稳定阶段;高填方宽幅沥青路面-路基体系吸热面积与散热面积的同时增加导致宽幅路基路面体系不同横向位置和深度处温度场更为复杂;沥青路面宽度从5m增加到24.5m导致最大融化深度增加量在1.5~2.0m。在中低纬度高海拔多年冻土区设计宽幅公路路基填土高度时应考虑具体路基断面特点,计算极端天气下的宽幅路基路面体系从建设期到稳定期的温度场,保证阳面路肩一侧融化深度始终满足要求     

路堤填筑压实的公式化控制

兰州市北滨河路银(银滩黄河大桥)农(甘肃农业大学)段,长1 650m,Ⅰ级城市主干道,路幅宽度42m,全线土石方工程量:填方47·992万m3,挖方178·75m3。根据工程地质勘察报告,工程沿线地基土的地层结构简单,以素填土、粉土、粉砂、粉质粘土为主。根据施工图设计文件,路基设计标高以设防标准为黄河百年一遇流量6 500m3/s的河堤标高进行控制,平均填土高4~7m,局部地段因挖沙取土形成深沙坑,填土在10~12m。本工程填土量大,平均每公里填方达29·09万m3,路基填土主要取自路基沿线的黄河沿岸,主要类别为素土、砂砾以及砂砾土等。工程的重型击实试验结果如…     

高速公路高填方路基施工关键技术

以某高速公路高填方路基工程施工为例,其填土高度超过20 m(石质),土体压力较大,为避免路基出现沉降过大、纵向开裂等问题,应做好路基施工质量控制。因此,总结该工程高填方路基特征,并将材料控制、路堑开挖、路基压实、沉降监测等作为切入点,对高填方路基施工关键技术进行分析。     

反压护道对填土路基的稳定性影响研究

反压护道是软基上填土路基工程常用的处理方式之一。针对填土路基工程中的软基问题,采用数值分析软件OptumG2对反压护道处理方式进行了数值分析。结果表明:未经处理的路基填土的安全系数为1.242,低于现有的相关规范给出的安全系数1.30,不满足相关规范的要求,路基填土存在潜在的失稳破坏;反压处理后,路基填土的安全系数增加,满足相关规范的要求;考虑路基填土的经济性和安全性,优先选取反压护道的高度为3 m,宽度为4 m,安全系数为1.461,增加17.63%;随着反压护道的高度增加,其安全系数增加,但是反压护道的高度增加到较大时,继续增加高度,其安全系数反而下降;随着反压护道的宽度增加,其安全系数增加,但是反压护道的宽度增加到较大时,继续增加宽度,其安全系数变化不大。     

高速公路路基最小填土高度的计算与探讨

针对平原微丘区高速公路路基多以低填为主、土石方多以借方为主的情况,提出路基填土的高度直接关系到高速公路的安全运营和土石方数量的大小,因此确定路基的最小填土高度显得尤其重要,对路基最小填土高度的计算进行了详细的介绍。     

成都地区深基坑支护的几种主要做法

成都市区地基土主要由岷江水系第四系全新冲洪积层的粉质粘土、粉土、砂、卵石构成,上覆人工填土,下覆白垩系泥岩,由上至下各层土的厚度为: 人工填土:上为杂填土、下为素填土厚度2.5～4.0m。 粉土:厚度1.0～2.5m。 砂土:粉砂、细砂,厚度0.5～3.0m。 卵石:上为稍密,厚0.5～2.0m;局部有细砂透镜体,下为中密及密实,总厚度15～20m,卵石层顶面距地表4～9m。 泥岩:离地表约20～25m。 地下水埋深1～3m。 成都市区高层建筑基础或地下室底板一般放置在中密及密实卵石层上,以此作为     

黄土地区公路路基沉降变形有限元分析

针对黄土地区公路工程特点,将地基、路基作为整体,采用有限元法建立分析模型,计算分析了地基土变形模量、填土高度、填土容重、填土回弹模量各参数对路表最终沉降量和路表不均匀沉降的影响变化规律,以指导黄土地区公路路基设计。     

虹口港、杨浦港地区旱流污水截流工程设计水量的论证

对虹口港、杨浦港地区近几年来产业结构调整 ,污染大户的外迁 ,工业废水量明显减少的情况进行调研 ,通过对现状污水量的采集 ,规划、现状水量的测定等进行了详细的分析和论述 ,比较客观合理确定虹口港、杨浦港地区旱流污水截流工程的设计污水量     

工作流设计案例分析——房产管理系统中的工作流设计

工作流的设计概念应用到软件系统中,将工作过程分解成任务、角色,按照一定的规则来执行这些任务并对它们进行监控,可以提高办事效率、降低房产管理成本,提升企业经营管理水平和企业市场竞争力。房产管理系统中借鉴工作流的概念,可有效地提高管理人员的技术水平。     

变频调速与管网叠压供水系统小流量工况分析与对策探讨

在用水低谷期出现的生活给水系统小流量是造戍水泵运行效率低下、影响变频供水系统节能效果的重要因素之一.通过实测数据分析验证了变频调速供水系统在小流量工况下的高能耗现象;在分析变频调速泵特性曲线的基础上分别推求出满足水泵高效运行和变频可调速的最小流量,为水泵的选取提供理论依据;结合实例阐述了克服小流量不利影响的技术措施.     

水利工程明渠均匀流水力计算探讨

结合工程实例,阐述了水利工程明渠均匀流的计算方法及计算注意事项,对其中的有关水力专业名词及计算作出详细解释.     

An analysis of compartment fire doorway flows

A mathematical study is made to compute the doorway flow behavior due to fire in a room. Two approaches were taken, first a model attempting to include the effect of fire entrainment and vent mixing; second was a model based on an ideal point source plume fire—both in the zone model concept. Limiting analytic results were found for the latter to give insight into the physics. The results were compared to available flow data, and an approximate formula was developed to predict the doorway mass flow rate to within 20% for a wide range of fire conditions. CFD computations were also explored using FDS. Results are compared from FDS and the zone model with experimental data for a wide range of variables.     

供热系统中调节阀的研究与应用

依据调节阀流量特性的数学方程，导出了流量特性分别为直线型和等百分比型调节阀流通截面积的计算公式，指出了现有调节阀阀芯形状设计中存在的问题，分析了供热系统中调节阀的选用原则，认为应根据流通能力来计算选择调节阀的口径，而不是由连接管的管径来确定，并认为调节阀的安装地点不同，其计算公式中的系数有差别。     

Characterization of two-phase flow in a single rock joint

An experimental study using a triaxial apparatus was used to analyze the two-phase flow patterns in jointed rock specimens. Rock specimens having a single natural fracture were tested for two-phase flow of water and air. Triaxial tests were conducted to characterize the two-phase flow through fractured granite specimens at low confining pressures. It was found that for a relatively smooth joint (JRC<6), bubble flow pattern occurred within the rock joint when the gas velocity is below 15 m/s. The average velocity of water usually varied between 0.1 and 0.5 m/s for bubble flow patterns. In this velocity range, air bubbles were able to form along the joint walls or to be randomly displaced within the water phase. When the gas velocity inside the rock joint exceeded 22 m/s, the flow patterns took annular form for non-zero capillary pressures (i.e., injected gas pressure is not equal to injected water pressure). At elevated (>0.25 MPa) gas injection pressures, the gas occupied the main part of the fracture and the liquid was able to flow as an unstable film forming an annular flow along the joint. When the annular flow developed, the mixture flow pattern was independent of the air flow velocity. This was due to the fact that once the injected air velocity reached a critical value (i.e., 20 m/s), water velocity inside the joint was negligible for a given confining pressure and injected water pressure. Further increase in inlet air pressures developed a single-phase air flow with no water flow.     

雨水口的流量计算方法探讨

基于水力学理论以及对美国相关规范的研究,提出雨水口设计流量的计算方法。并以计算示例验证了《雨水口》(05S518)标准图集中规定的泄水能力不准确,建议实际工程中应以道路坡度、箅前设计水深、雨水口型式及尺寸等为条件进行具体的设计流量计算,以确定雨水口的设计与布置。     

Study on performance of horizontal single pass shell and multi-tube heat exchanger with baffles by air bubble injection

ABSTRACT

The single pass shell and multi-tube heat exchanger with double segmental baffles'’ performance improvement were experimentally investigated by two methods of air injection into shell side when an increase in air bubble created an effect in the corresponding values of shell and tube heat exchanger such as the overall heat transfer coefficient, effectiveness, NTU and the pressure loss. In the first method, air bubble injection into shell side was parallel to the cold water flow; also in the second method, air bubble injection into shell side was cross flow to the cold water with different air flow rates to calculate approximately the most favourable performance conditions. 1–6?LPM of air flow rates and 10–20?LPM shell side water flow rates were transformed with constant tube side hot water flow rate.     

The importance of gully flow modelling to urban flood simulation

ABSTRACT

Urban flood simulation often ignores or simplifies the function of underground gully systems due to data and computational limitations. To discover the influence of gullies on urban flooding, a novel approach is proposed in this study, by fully-coupling a 1D gully flow model (GFM), a 1D sewer flow model (SFM), and a 2D overland flow model (OFM) to simultaneously simulate the flow exchanges between surface, gullies and sewer pipes. This fully-coupled approach is compared with a simplified approach which directly introduces surface water into sewer pipes without being via gullies. The validation results show that the fully-coupled approach considerably reduces the underestimation of flood extent by 27% compared with the simplified approach. Without considering the capacity of lateral tubes between gullies and sewer pipes, the simplified approach over-drains the surface water into sewer pipes. The modelling of gully flow is crucial for correctly evaluating the efficiency of drainage systems.