承压舟浮桥许用V型坡度研究

V型坡度是影响承压舟浮桥安全营运的一个重要因素,本文对第四代承压舟浮桥不同V型坡度引起的轴重变化进行了研究,进行了V型坡实桥试验和V型坡模型试验,得到了六轴大载重挂车在V型坡度分别为1%,2%,3%和4%时轴重变化情况。根据承压舟浮桥长期营运经验,分析并确定了承压舟浮桥安全营运时的许用V型坡度。

城市“W”型中长距离沉管隧道火灾烟气运动规律研究

面对城市内河存有江中岛情况,过江隧道普遍采用“W”型的纵断面形式。揭示城市“W”型过江隧道火灾烟气运动规律具有重要意义。利用火灾动力学软件(FDS),采用数值模拟方法研究了交通正常、拥堵工况下城市“W”型中长距离沉管隧道火灾烟气蔓延范围和隧道顶部温度、流速分布规律。结果表明:交通正常时,临界风速可以较好控制城市“W”型隧道内不同区间发生火灾时的烟气;交通拥堵时,沙岛段发生火灾时危险性最高,1 800 s时烟气还有继续蔓延的趋势。交通正常时隧道顶部最高温度均小于300℃;交通拥堵时,沙岛段隧道顶部最高温度约423℃,沉管段隧道顶部最高温度约387℃,出入口段隧道顶部最高温度约350℃~400℃。交通正常时,火源下游流速明显高于上游流速;交通拥堵时,火源处流速最大,随着距离增加,流速整体呈现衰减趋势,隧道顶部流速会随坡度变化波动。

山区地下车库整体设计研究

本文以"土地节约型"的山区地下停车库的整体设计为主题,以提高土地利用率为主要目标,同时要兼顾停车停车便利性,对山地地下停车库的设计方法及注意事项进行了分类、举例说明计方法和要点——机械停车、坡度型、分段型。整体设计在山区地下车库的设计中起到很大的引导作用,原始地形、地上建筑和景观也都是需要在设计中不断进行相互的调整。

Study on Soil Erosion Model Under Different Slopes in Southwest Karst Mountain Area

The aim was to further research soil erosion characteristics and accurately predict soil erosion amount in karst areas. Based on field surveys and research achievements available, yellow soils, which are widely distributed, were chosen as test soil samples and slope, rain intensity, vegetation coverage and bare-rock ratio were taken as soil erosion factors. Artificial rain simulation instruments （needle-type） were made use of to simulate correlation of rain intensity, vegetation coverage, and bare-rock ratio with soil erosion quantity. Furthermore, multiple-factor linear regression analysis, stepwise regression analysis and multiple-factor non-linear regression analy- sis were made to establish a multiple-factor formula of soil erosion modulus with dif- ferent slopes and select regression models with high correlation coefficients. The re- sults show that a non-linear regression model reached extremely significant level or significant level （0.692〈FF〈0.988） and linear regression model achieved significant lev- el （0.523〈FF〈0.634）. The effects of erosion modulus changed from decreasing to in- creasing and the erosion factors from high to low were rain intensity, vegetation cov- erage and bare-rock ratio when slope gradient was at 6~, 16~, 26~ and 36~. The mod- el is of high accuracy for predicting gentle slope and abtupt slope, which reveals correlation of erosion modulus with erosion factors in karst areas.

Dynamic Change and Simulation and Prediction of the Karst Rocky Desertification Sensitivity in Guizhou Province

Sensitivity evaluation of rocky desertification is to recognize the areas prone to be rock-deserted,so as to assess the sensitivity degree of rocky desertification to human activities.To perform the sensitivity evaluation of rocky desertification,we should be on the basis of the mechanism of rocky desertification formation for analyzing its regional distribution difference in the sensitivity and further for finding out the rocky desertification-susceptive areas and their possible degrees.Employing remote sensing and geological information system techniques,we regarded the 1∶ 50 000 topographic map and the TM image in 2000 of Guizhou Province,together with the hydrologic map,soil map,geologic map,rock formation map,administrative map and other geological information as data sources to generate the degree data of rocky desertification sensitivity of Guizhou Province in 1962 and 2000,based on which we determined the corresponding degree transfer matrix and adopted Markov model to simulate the dynamic change process of rocky desertification sensitivity and its future evolution trend.In various sensitivity types of rocky desertification in Guizhou Province,only the insensitive type showed a declined acreage,from the proportion of total land acreage of 61.35% in 1962 to 55.55% in 2000.Various sensitivity types inter-conversed,resultantly the acreage of mildly sensitive type increased most.The prediction results showed that the acreage of insensitive type of rocky desertification in Guizhou Province will assume a remarkable decline trend,of mildly sensitive type will present a remarkably increasing trend and of slightly sensitive type basically will maintain a stable level in the future tens of years.Acreages of both highly sensitive and extremely sensitive type of rocky desertification expanded to some extent,suggesting that the rocky desertification risk in Guizhou Province is in an aggravating process.

构造稳定时期河控三角洲三元控砂模式

三角洲砂体是含油气盆地勘探的最主要储集体类型之一,湖相三角洲类型基本均为河控型三角洲。明确河控三角洲砂体发育机制、迁移规律、分布特征、组合结构等规律不仅具有科学意义,而且对于油气勘探具有重要的指导意义。影响河控三角洲砂体的因素较多,宏观上构造活动控制了盆地的类型、形成、演化、沉积底型形态、坡度及物源等。在构造相对稳定时期,河控三角洲砂体主要受3种因素控制:物源供屑能力(简称物源),沉积底型坡度(简称坡度)和湖岸线位置(简称岸线)。物源供屑能力控制了砂体规模,体现在粒度、砂体厚度及范围;底型坡度控制了砂体宽厚比,表现在砂体前积层角度大小及三角洲形状;湖岸线河口处是沉积物主要卸载区,其位置及迁移幅度控制了砂体位置及连续性。3种因素不同的变化组合形成了不同特征的三角洲砂体分布模式。

Automatic prediction of time to failure of open pit mine slopes based on radar monitoring and inverse velocity method

Radar slope monitoring is now widely used across the world, for example, the slope stability radar(SSR)and the movement and surveying radar(MSR) are currently in use in many mines around the world.However, to fully realize the effectiveness of this radar in notifying mine personnel of an impending slope failure, a method that can confidently predict the time of failure is necessary. The model developed in this study is based on the inverse velocity method pioneered by Fukuzono in 1985. The model named the slope failure prediction model(SFPM) was validated with the displacement data from two slope failures monitored with the MSR. The model was found to be very effective in predicting the time to failure while providing adequate evacuation time once the progressive displacement stage is reached.

天津地铁积水区段行车组织措施分析

针对积水线路积水没过轨面情况,现有规定“积水没过轨面的停止列车通过”,参考其他地铁行车措施,尝试进行修订。以车辆最大涉水能力作为硬性约束条件,利用线路最大坡度对称形式下作为最差工况,计算此时积水没过轨面的水平距离,取各条线路积水没过轨面的水平距离的最小值作为限速依据阈值。验证积水没过轨面时水平距离的合理性:最差工况下积水没过轨面的水面距离阈值反向求得各条线路积水没过轨面高度,均小于车辆最大涉水能力;考虑到地铁正线车站横截面以梯形形式存在的情况,计算获得出现积水没过轨面深度值刚好达到人为设定列车最大涉水深度时坡底水平距离在各正线中不存在。根据积水距离调整积水区段的限速措施,为提升现场执行,配合设置水位标线综合判断后采取行车措施,以期达到积水区段运营安全与运营效率平衡双优。

Effect of Lithology and Structure on Seismic Response of Steep Slope in a Shaking Table Test

Studies on landslides by the 2008 Wenchuan earthquake showed that topography was of great importance in amplifying the seismic shaking, and among other factors, lithology and slope structure controlled the spatial occurrence of slope failures. The present study carried out experiments on four rock slopes with steep angle of 60° by means of a shaking table. The recorded Wenchuan earthquake waves were scaled to excite the model slopes. Measurements from accelerometers installed on free surface of the model slope were analyzed, with much effort on timedomain acceleration responses to horizontal components of seismic shaking. It was found that the amplification factor of peak horizontal acceleration, RPHA, was increasing with elevation of each model slope, though the upper and lower halves of the slope exhibited different increasing patterns. As excitation intensity was increased, the drastic deterioration of the inner structure of each slope caused the sudden increase of RPHA in the upper slope part. In addition, the model simulating the soft rock slope produced the larger RPHA than the model simulating the hard rock slope by a maximum factor of 2.6. The layered model slope also produced the larger RPHA than the homogeneous model slope by a maximum factor of 2.7. The upper half of a slope was influenced more seriously by the effect of lithology, while the lower half was influenced more seriously by the effect of slope structure.

Composition and structure of species along altitude gradient in Moghan-Sabalan rangelands,Iran

This study provides a checklist of species distributed at the altitude gradient of MoghanSabalan rangelands in Ardabili province, Northwest Iran. We evaluated the changes in species composition, growth types of species, Raunkiaer's life forms, geographical distribution, threat and endemicity status, and palatability of species along two altitudinal gradients in the sampling plots, which were conducted in eleven sites/habitats with 300 meters above sea level(masl) altitude intervals(from 100 to 3300 masl). We assessed the plant species composition with special reference to the gradient analysis, and identified overall 396 species, which was comprising 44 families and 194 genera. Results showed that Asteraceae family is by far the most species-rich family, followed by Poaceae, Fabaceae, Caryophyllaceae and Brassicaceae. Among the genera, Astragalus is the most diverse genus, followed by Allium, Veronica and Bromus, Galium, Silene and Ranunculus. Results indicated that the number of species increased as the altitude increased to 1200-1500 masl, but then starts to decline to 3300 masl. Family-to-genera ratio was 1:4.4, the family-tospecies ratio was 1:9, and the genera-to-species ratio was 1:2.04. Growth type of species analysis shows that the frequency of perennial plants was higher in the study area followed by annual species while the lower group was biennial species. The number of annuals showed a decreasing trend towards higher altitude. Hemicryptophytes and therophytes were the most frequent life forms constituted each with(41.9%). Hemicryptophytes showed an increasing trend with altitude, while therophytes showed a decreasing trend with altitude increase, followed by geophytes, chamaephytes, and phanerophytes. Results showed more than half of the species of the study area belonged to Iran-Turanian region and these species showed an increasing trend with altitude. In contrast, Sahara-Sindian species comprise a minor component of the spectrum, with decreasing trend with altitude. The rare and endangered species out of the surveyed taxonomic groups comprised 53 species in total which 29 of them are considered lower risk(LR), 13 data deficient(DD), 5 vulnerable(Vu) and with 3 rare(R) and identified endemic plants comprised 24 species. Some 56.6% species were identified as class III, 22.6% were class I and 20.8% were class II as the palatability variation. Moghan-Sabalan rangelands require strong conservation management policies in case of species loss and changing natural communities due to the occurrence of conversion into cropland, over-grazing and other anthropogenic effects.

Topographic Characteristics for the Geomorphologic Zones in the Northwestern Edge of the Qinghai-Tibet Plateau

Based on geomorphologic and digital elevation model(DEM) data, the topographic characteristics of the northwestern edge of the Qinghai-Tibet Plateau are analyzed. Five representative peaks are first determined according to the topographic profile maps for the ridge and piedmont lines, and then the topographic gradient characteristics are analyzed according to the representative topographic profile acquisition method.Based on the geomorphologic database data, the regions between the ridge and the piedmont lines are divided into four geomorphologic zones; and the topographic characteristics are finally analyzed for the different geomorphologic zones regions using the DEM data. The research results show that from the piedmont to the ridge, there exist four geomorphologic zones: arid, fluvial, periglacial and glacial. The arid has the lowest elevation, topographic gradient, relief and slope characteristics. The fluvial has lower elevation and the highest topographic gradient, but with lower relief and slope characteristics. With higher elevation, the periglcial has lower topographic gradient, but the highest relief and slope characteristics. The glacial has the highest elevation with higher topographic gradient, relief and slope characteristics.

An Elastic-Plastic Iceberg Material Model Considering Temperature Gradient Effects and its Application to Numerical Study

To simulate the FPSO-iceberg collision process more accurately, an elastic-plastic iceberg material model considering temperature gradient effects is proposed and applied. The model behaves linearly elastic until it reaches the ‘Tsai-Wu’ yield surfaces, which are a series of concentric elliptical curves of different sizes. Decreasing temperature results in a large yield surface. Failure criteria, based on the influence of accumulated plastic strain and hydrostatic pressure, are built into the model. Based on published experimental data on the relationship between depth and temperature in icebergs, three typical iceberg temperature profiles are proposed. According to these, ice elements located at different depths have different temperatures. The model is incorporated into LS-DYNA using a user-defined subroutine and applied to a simulation of FPSO collisions with different types of icebergs. Simulated area-pressure curves are compared with design codes to validate the iceberg model. The influence of iceberg shape and temperature on the collision process is analyzed. It is indicated that FPSO structural damage not only depends on the relative strength between the iceberg and the structure, but also depends on the local shape of the iceberg.

Performance Analysis of Plug-in Hybrid Passenger Vehicles

PHEVs （passenger plug-in hybrid electric vehicles） have shown significant fuel reduction potential. Furthermore, PHEVs can also improve longitudinal vehicle dynamics with respect to acceleration and engine elasticity. The objective of this study is to investigate potential of concurrent optimization of fuel efficiency and driving performance. For the studies, a backward vehicle model for a parallel PHEV was designed, where the power flow is calculated from the wheels to the propulsion units, the conventional ICE （internal combustion engine） and the EMG （electric motor/generator） unit. The hybrid drive train is according to a P2 layout, consequently the EMG is situated between the shifting clutch and the ICE. The implemented operation strategy distributes the power to both propulsion units depending on the vehicle speed, requested driving torque, the battery＇s SOC （state of charge） and SOP （state of power）. Additional information, such as the slope of the road, can be taken into account by the operation strategy. In the paper, the fuel saving potential as well as the longitudinal dynamics change of different PHEV configurations is presented as a function of battery capacity and EMG power. Consequently, applicable hybrid components can be defined. By using additional information of the environment like various sensor data, road slope amongst others, the fuel saving potential can be improved even more. By studying the dynamic model, the overall results of the backward model are confirmed. In conclusion, this study shows that it is possible to concurrently reduce fuel consumption and increase driving performance in PHEVs. The potential depends strongly on the configuration of the electric components and the implemented operation strategy. Consequently, the hybrid system configuration has to be chosen carefully and aligned to the vehicle performance.