武汉地铁及长江隧道沿线地下管线现状分析     

李黎 《现代测绘》2004,27(2):43-44

本文论述了利用城市地下管线信息系统对武汉地铁和长江隧道沿线进行地下管线现状调查的过程和方法，结果表明利用该系统所完成的分析和成果资料满足了武汉及长江隧道沿线工程可行性研究的需要。  相似文献   

视电阻率观察中一种抗介质干扰的尝试     

唐宇雄  张茂军  夏坤涛  龙明友  李绍坤  颜晓晔 《四川地震》2005,(4):40-46

埋地金属管线对视电阻率的观测危害甚大。造成观测值大幅改变，跳动，无规律可循。严重时，甚至台站报废，被迫搬迁。通过一些突发事件的启发，结合现场实验，并引证了一些理论计算，笔者摸索出了只须对金属管道作局部微小的改造，就能基本克服其对观测的干扰的方法。该方法在红格台试验半年多来，取得了明显的效果。观测值恢复到安装的水管以前的水平，再无大幅度的跳动。该方法节约经费，简单易行，大大提高了台站在复杂环境中的生存能力。  相似文献   

Channel adjustments of the lower Trinity River,Texas, downstream of Livingston Dam     

Jonathan D. Phillips  Michael C. Slattery  Zachary A. Musselman 《地球表面变化过程与地形》2005,30(11):1419-1439

Channel cross‐sectional changes since construction of Livingston Dam and Lake Livingston in 1968 were studied in the lower Trinity River, Texas, to test theoretical models of channel adjustment, and to determine controls on the spatial extent of channel response. High and average flows were not significantly modified by the dam, but sediment transport is greatly reduced. The study is treated as an opportunistic experiment to examine the effects of a reduction in sediment supply when discharge regime is unchanged. Channel scour is evident for about 60 km downstream, and the general phenomena of incision, widening, coarsening of channel sediment and a decrease in channel slope are successfully predicted, in a qualitative sense, by standard models of channel response. However, there is no consistent channel response within this reach, as various qualitatively different combinations of increases, decreases or no change in width, depth, slope and roughness occur. These multiple modes of adjustment are predicted by the unstable hydraulic geometry model. Between about 60 km and the Trinity delta 175 km downstream of the dam, no morphological response to the dam is observed. Rather than a diminution of the dam's effects on fluvial processes, this is due to a fundamental change in controls of the fluvial system. The downstream end of the scour zone corresponds to the upstream extent of channel response to Holocene sea level rise. Beyond 60 km downstream, the Trinity River is characterized by extensive sediment storage and reduced conveyance capacity, so that even after dam construction sediment supply still exceeds transport capacity. The channel bed of much of this reach is near or below sea level, so that sea level rise and backwater effects from the estuary are more important controls on the fluvial system than upstream inputs. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Channel geometry of mountain streams in New Zealand     

Ellen E. Wohl  Andrew Wilcox 《Journal of Hydrology》2005,300(1-4):252-266

A dataset of 21 study reaches in the Porter and Kowai rivers (eastern side of the South Island), and 13 study reaches in Camp Creek and adjacent catchments (western side of the South Island) was used to examine downstream hydraulic geometry of mountain streams in New Zealand. Streams in the eastern and western regions both exhibit well-developed downstream hydraulic geometry, as indicated by strong correlations between channel top width, bankfull depth, mean velocity, and bankfull discharge. Exponents for the hydraulic geometry relations are similar to average values for rivers worldwide. Factors such as colluvial sediment input to the channels, colluvial processes along the channels, tectonic uplift, and discontinuous bedrock exposure along the channels might be expected to complicate adjustment of channel geometry to downstream increases in discharge. The presence of well-developed downstream hydraulic geometry relations despite these complicating factors is interpreted to indicate that the ratio of hydraulic driving forces to substrate resisting forces is sufficiently large to permit channel adjustment to relatively frequent discharges.  相似文献   

岩土钻掘设备的液压步履机构          下载免费PDF全文

王世玉  薛军 《探矿工程》2005,32(6):41-43

因液压步履移位最方便，辅助时间短，换向灵活，移位对孔准确，大型岩土钻掘设备施工的群孔现场实现近距离的自行迁移多采用液压步履机构。详细叙述了双向移动和单向移动加转向步履机构的结构和特点。  相似文献   

The effect of conservation practices in sloped croplands on soil hydraulic properties and root‐zone moisture dynamics          下载免费PDF全文

Lirong Lin  Jiazhou Chen 《水文研究》2015,29(9):2079-2088

Rain‐induced erosion and short‐term drought are the two factors that limit the productivity of croplands in the red soil region of subtropical China. The objective of this study was to estimate the effects of conservation practices on hydraulic properties and root‐zone water dynamics of the soil. A 3‐year experiment was performed on a slope at Xianning. Four treatments were evaluated for their ability to reduce soil erosion and improve soil water conditions. Compared with no practices (CK) and living grass strips (GS), the application of polyacrylamide (PAM) significantly reduced soil crust formation during intense rainfall, whereas rice straw mulching (SM) completely abolished soil crust formation. The SM and PAM treatments improved soil water‐stable aggregates, with a redistribution of micro‐aggregates into macro‐aggregates. PAM and SM significantly increased the soil water‐holding capacity. These practices mitigated the degradation of the soil saturated hydraulic conductivity (Ks) during intense rainfalls. These methods increased soil water storage but with limited effects during heavy rainfalls in the wet period. In contrast, during the dry period, SM had the highest soil water storage, followed by PAM and CK. Grass strips had the lowest soil water storage because of the water uptake during the vigorous grass growth. A slight decline in the soil moisture resulted in a significant decrease in the unsaturated hydraulic conductivity (Ku) of the topsoil. Therefore, the hydraulic conductivity in the field is governed by soil moisture, and the remaining soil moisture is more important than improving soil properties to resist short‐term droughts. As a result, SM is the most effective management practice when compared with PAM and GS, although they all protect the soil hydraulic properties during wet periods. These results suggest that mulching is the best strategy for water management in erosion‐threatened and drought‐threatened red soils. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Synthesis of soil‐hydraulic properties and infiltration timescales in wildfire‐affected soils          下载免费PDF全文

Brian A. Ebel  John A. Moody 《水文研究》2017,31(2):324-340

We collected soil‐hydraulic property data from the literature for wildfire‐affected soils, ash, and unburned soils. These data were used to calculate metrics and timescales of hydrologic response related to infiltration and surface runoff generation. Sorptivity (S) and wetting front potential (Ψ_f) were significantly different (lower) in burned soils compared with unburned soils, whereas field‐saturated hydraulic conductivity (K_fs) was not significantly different. The magnitude and duration of the influence of capillarity during infiltration was greatly reduced in burned soils, causing faster ponding times in response to rainfall. Ash had large values of S and K_fs but moderate values of Ψ_f, compared with unburned and burned soils, indicating ash has long ponding times in response to rainfall. The ratio of S²/K_fs was nearly constant (~100 mm) for unburned soils but more variable in burned soils, suggesting that unburned soils have a balance between gravity and capillarity contributions to infiltration that may depend on soil organic matter, whereas in burned soils the gravity contribution to infiltration is greater. Changes in S and K_fs in burned soils act synergistically to reduce infiltration and accelerate and amplify surface runoff generation. Synthesis of these findings identifies three key areas for future research. First, short timescales of capillary influences on infiltration indicate the need for better measurements of infiltration at times less than 1 min to accurately characterize S in burned soils. Second, using parameter values, such as Ψ_f, from unburned areas could produce substantial errors in hydrologic modeling when used without adjustment for wildfire effects, causing parameter compensation and resulting underestimation of K_fs. Third, more thorough measurement campaigns that capture soil‐structural changes, organic matter impacts, quantitative water repellency trends, and soil‐water content along with soil‐hydraulic properties could drive the development of better techniques for numerically simulating infiltration in burned areas.  相似文献   

A hydraulic invariance‐based methodology for the implementation of storm‐water release restrictions in urban land use master plans          下载免费PDF全文

Viviana Pappalardo  Alberto Campisano  Francesco Martinico  Carlo Modica  Luca Barbarossa 《水文研究》2017,31(23):4046-4055

A hydraulic invariance (HI)‐based methodology was developed as a tool to support implementation of storm flow control measures into land use master plans (LUMPs) for urban catchments. The methodology is based on the use of simple hydrologic analysis to compare predevelopment and postdevelopment catchment flow release scenarios. Differently from previous literature examples, for which the parcel scale is usually considered for the analysis, HI was pursued assuming the LUMP areas of transformation as the basic units for assigning storm water control measures in the form of flow release restrictions. The methodology was applied to a case study catchment in the southern part of the City of Catania (Italy), for which the LUMP re‐design has been recently proposed. Simulations were run based on the use of the EPA‐Storm Water Management Model and allowed deriving flow release restrictions in order to achieve HI at the subcatchment level for design events of different return period.  相似文献   

Hydrologic response of engineered media in living roofs and bioretention to large rainfalls: experiments and modeling          下载免费PDF全文

Ruifen Liu  Elizabeth Fassman‐Beck 《水文研究》2017,31(3):556-572

The hydrologic response of engineered media plays an important role in determining a stormwater control measure's ability to reduce runoff volume, flow rate, timing, and pollutant loads. Five engineered media, typical of living roof and bioretention stormwater control measures, were investigated in laboratory column experiments for their hydrologic responses to steady, large inflow rates. The inflow, medium water content response, and outflow were all measured. The water flow mechanism (uniform flow vs. preferential flow) was investigated by analyzing medium water content response in terms of timing, magnitude, and sequence with depth. Modeling the hydrologic process was conducted in the HYDRUS‐1D software, applying the Richards equation for uniform flow modeling, and a mobile–immobile model for preferential flow modeling. Uniform flow existed in most cases, including all initially dry living roof media with bimodal pore size distributions and one bioretention medium with unimodal pore size distribution. The Richards equation can predict the outflow hydrograph reasonably well for uniform flow conditions when medium hydraulic properties are adequately represented by appropriate functions. Preferential flow was found in two media with bimodal pore size distributions. The occurrence of preferential flow is more likely due to the interaction between the bimodal pore structure and the initial water content rather than the large inflow rate.  相似文献   

On the dependence of the saturated hydraulic conductivity upon the effective porosity through a power law model at different scales          下载免费PDF全文

Carmine Fallico  Samuele De Bartolo  Massimo Veltri  Gerardo Severino 《水文研究》2016,30(13):2366-2372

We study the scale dependence of the saturated hydraulic conductivity K_s through the effective porosity n_e by means of a newly developed power‐law model (PLM) which allows to use simultaneously measurements at different scales. The model is expressed as product between a single PLM (capturing the impact of the dominating scale) and a characteristic function κ^? accounting for the correction because of the other scale(s). The simple (closed form) expression of the κ^?‐function enables one to easily identify the scales which are relevant for K_s. The proposed model is then applied to a set of real data taken at the experimental site of Montalto Uffugo (Italy), and we show that in this case two (i.e. laboratory and field) scales appear to be the main ones. The implications toward an important application (solute transport) in Hydrology are finally discussed. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献