高等级公路沥青路面抗滑性能研究

在分析高等级公路沥青路面抗滑机理的基础上，通过研究影响抗滑性能的主要因素，结合国内外研究成果和工程经验，提出了高等级公路沥青路面提高抗滑性能的技术要点。     

黑龙江省高等级公路沥青路面抗滑表层初探

随着公路等级的不断提高 ,车辆的行驶速度也在加快 ,这对高等级公路路面的要求也就越来越高 ,因此 ,沥青路面表面的抗滑性能显得很重要。为此提出了调整沥青混合料级配 ,从而提高路面抗滑能力 ,并对验证级配的全过程进行了论述 ,在理论上为下一步的研究打下了坚实的基础。     

超粘精罩面在沥青路面预防性养护中的应用

沥青薄层罩面在沥青路面养护中被广泛应用,具有改善路面抗滑性能、防治路面早期病害、降噪等优点。提出一种超粘精罩面,通过在试验路段中的应用,阐述其技术要点、工艺流程。通过施工前与施工后的路面抗滑性能、平整度、渗水性能检测结果分析论证超粘精罩面对路面性能的影响。结果表明：超粘精罩面可以明显改善沥青路面的抗滑性能和平整度,同时采用半开级配结构使超粘精罩面比常规薄层罩面具有更高的空隙率,具有良好的疏水性能,能有效防止路面在雨天形成水膜,提高行车安全性。沥青薄层罩面种类较多,使用寿命和经济效益是决定养护方案选取的关键,根据研究结果,超粘精罩面具有很大优势,可在工程项目中进一步推广应用。     

水泥基木质碎料复合材料路用性能试验研究

以木质碎料、砂以及水泥为原料,采用振捣工艺制备了水泥基木质碎料复合材料,并对其力学性能及路用性能开展了试验研究。试验结果表明:所制备的试件抗折强度在1.5 MPa左右,抗压强度大于3.5 MPa;经过20次干湿循环后,抗压强度、抗折强度仍达28 d标准养护条件下试件力学强度的80%以上,并具有良好的抗滑性能和抗冲击性能。     

OGFC型降噪路面在我国的发展趋势

OGFC型降噪路面是在普通的沥青砼或水泥砼路面上铺筑一层大孔隙的沥青混合料.这种大孔隙能有效的降低车辆的行驶噪声,并在雨天可以减少水雾的产生,增大路面的抗滑性能,保证了行车的安全舒适.本文介绍了OGFC型降噪路面的技术特点、在我国的应用现状及发展前景.     

防滑降噪沥青路面磨耗层抗滑性能研究

为了研究防滑降噪沥青路面磨耗层的抗滑性能,跟踪实测了试验路段OGFC-13抗滑磨耗层的构造深度与横向摩擦系数,并与相邻密级配沥青路面试验路段面层的测量结果进行了对比,结果表明:防滑降噪沥青路面的构造深度随时间而出现衰减,但还是要比密级配沥青路面的构造深度大得多;防滑降噪沥青路面磨耗层横向摩擦系数出现持续增大的规律,与密级配沥青路面的变化规律不一致,防滑降噪沥青路面后期表现出抗滑特性优势。     

沥青路面抗滑技术

沥青路面抗滑技术该技术是以沥青路面微观构造（选用抗滑石料）、宏观构造（选用合适级配和工艺）和采取防止滑溜性污染的措施（封闭粘性土路肩），来达到提高路面高速和低速下抗滑性的成套技术。采用该套技术后，在雨天可减少汽车的制动距离降低汽车的侧滑危险，消除汽车...     

高速公路沥青路面薄层罩面养护技术与施工方法分析

结合某高速公路工程案例,对高速公路沥青路面薄层罩面养护技术与施工方法要点进行分析,同时利用平整度、抗滑性能等指标对施工质量进行检验。结果表明:利用该技术可以有效提升高速公路路面施工质量以及高速公路使用寿命。     

路面含砂雾封层养护施工技术研究

近年来，公路建设规模持续扩大，公路养护任务越来越重要。含砂雾封层是预防性养护施工技术之一，具有延缓沥青路面老化、提高路面抗滑能力、改善路面使用性能、降低养护成本等特点。在全面了解含砂雾封层性能特点的基础上，依托某具体案例，对路面含砂雾封层养护施工技术要点和施工效果进行了分析与探讨，以期提高路面行车舒适性和安全性。     

水泥混凝土路面抗滑问题的探讨

本文主要分析了影响路面抗滑的主要因素，以及水泥混凝土路面的抗滑措施。     

路面养护中微表处技术探究

微表处技术以其较好的密封性、抗滑性、耐磨性,及防止公路沥青路面的老化与松散,有效地延长公路路面的使用寿命,从而得到广泛的应用。本文分析沥青路面养护和处治技术中微表处技术的材料性能和油石比的确定,并对旧沥青路面微表处施工技术进行初步的探究。     

钻孔孔壁粗糙度对钻孔灌注桩桩侧阻力的初步认识

本文给出孔壁粗糙度的描述方法及其与桩侧阻力之间的关系。通过分析试验结果，研究了孔壁粗糙度对钻孔灌注桩桩侧阻力的影响。表明孔壁粗糙度越大，相应的桩侧阻力就越大，从而提高钻孔灌注桩的承载力。     

Soil disturbance and post-logging forest recovery on bulldozer paths in Sabah, Malaysia

We examined the extent of soil disturbance associated with bulldozer yarding and the regrowth of woody vegetation on bulldozer paths (skid trails) in selectively logged dipterocarp forest. In an area logged in 1993, using conventional, i.e., uncontrolled, harvesting methods, about 17% of the area was covered by roads and skid trails. In contrast, in a 450-ha experimental area where reduced-impact logging guidelines were implemented, 6% of the area was similarly disturbed. Skid trails in the reduced-impact logging areas were less severely disturbed than those in conventional logging areas; the proportion of skid trails with subsoil disturbance was less than half that in conventional logging areas. Four years after logging, woody plant recovery on skid trails was greater in areas logged by reduced-impact than by conventional methods. Skid trails where topsoil had been bladed off had less woody vegetation than skid trails with intact topsoil. In a chronosequence of logging areas (3, 6, and 18 years after logging), species richness and stem densities of woody plants (>1 m tall, <5 cm dbh) were lower on skid trail tracks than on skid trail edges or in adjacent forest. Both richness and density increased with time since logging, but even 18 years after logging, abandoned skid trails were impoverished in small woody stems compared with adjacent forest. Minimizing soil and stand disturbance during logging appears to allow a more rapid recovery of vegetation on bulldozed soils, but the long-term fate of trees growing on compacted soils remains uncertain.     

冷轧工作辊的热处理试验

冷轧工作辊在工作过程中受力复杂，合理热处理后的机械性能可以在强度指标相当的情况下提高冷轧辊的抗断裂性、抗剥皮性、抗疲劳性能提高其工作质量。     

Long-term assessment of soil physicochemical properties and seedlings establishment after skidding operations in mountainous mixed hardwoods

One of the basic requirements for sustainable forest management in mixed broadleaved stands is to provide suitable conditions for natural regeneration of trees. These conditions include, but are not limited to, the frequency, quality and the composition of seedling species. Compacted soil layers caused by forest machinery traffic are the most common problem affecting seedling establishment and growth after skidding operations. In this study, we evaluated the frequency, quality, diversity of seedling species and physicochemical properties of soil on 10-, 20- and 30-year-old abandoned skid trails. Further comparison to the values of the mentioned above parameters in control areas allowed for the evaluation in terms of natural recovery processes, under varying traffic intensity and the longitudinal slope of the skid trails in a mixed broadleaved forest. Results showed that there is a significant positive trend of recovery for soil physicochemical properties and ecological characteristics (density and quality) of seedling growing on the skid trails. The time required to recover soil properties and ecological attributes of seedlings increased with increasing traffic intensity and slope of the skid trail. Our results showed that it takes 20 and 30 years to fully recover the chemical and physical properties of the soil, respectively. On the 30-year-old skid trails, density and species diversity indices were fully recovered, but the quality of the seedlings was not restored to the control conditions. The results suggest the importance of a proper planning of the skid trail network, avoiding in particular skid trails with a slope gradient higher than 20%.

     

Mitigating effects of slash on soil disturbance in ground-based skidding operations

Reinforcement of skid trails with slash has been shown to reduce soil disturbances, but there have not been any studies documenting the mitigating effects following traffic of harvest equipment traffic on steep mountainous skid trails. The objective of this study was to quantify potentially mitigating effects of slash cover on soil compaction and rutting on skid trails in mountainous hardwood forests. The effects of the placement of no slash (bare soil), light density slash (7.5 kg m^?2) and heavy density slash (17.5 kg m^?2) in a skid trail following one, five, and nine machine passes on both gentle slopes <20% and steep slopes >20% in a downhill skidding operation by a steel-tracked skidder were studied. Bulk density and rut depth increased following harvest equipment traffic on both slope gradients. Compared to bare soils, soil bulk density was not significantly reduced by light slash density; however, soil bulk density was significantly reduced by heavy slash up to five machine passes on steep slopes. Light and heavy slash significantly reduced rut depth in both slope classes. The study revealed a high protective role of slash, particularly on steep skid trails. However, benefits of slash to mitigate soil compaction were limited to five passes, after which the slash deteriorated and only provided benefits against rutting.     

Factors affecting soil-based natural regeneration of <Emphasis Type="Italic">Abies sachalinensis</Emphasis> following timber harvesting in a sub-boreal forest in Japan

Natural regeneration of Abies sachalinensis on soil was studied in a natural sub-boreal forest managed by single tree selection cutting located within the Hokkaido Tokyo University Forest. First, seedlings of A. sachalinensis on skid trails, soil mounds, soil pits, and undisturbed soil were counted, and their areas were measured. Most seedlings were found on skid trails. Seedling densities of A. sachalinensis on sites with soil disturbance, with the exception of soil pits, were significantly greater than that on undisturbed soil. Second, densities of Sasa senanensis, heights of S. senanensis, and seedling densities of A. sachalinensis on skid trails and undisturbed soil in both a closed-canopy stand and in a canopy gap were compared. Seedling density of A. sachalinensis on skid trails in the closed-canopy stand was significantly greater than that in the canopy gap. Average density and average height of S. senanensis, which is known to interfere with regeneration of many woody species, were significantly greater on skid trails and undisturbed soil in the canopy gap than those in the closed-canopy stand. It could be concluded from this study that both crown closure and soil disturbance are essential for natural regeneration of A. sachalinensis on soil in sub-boreal forests.     

Sugar maple (Acer saccharum Marsh.) growth is influenced by close conspecifics and skid trail proximity following selection harvest

In this study, we quantified the effects of local neighbourhood competition, light availability, and proximity to skid trails on the growth of sugar maple (Acer saccharum Marsh.) trees following selection harvest. We hypothesized that growth would increase with decreasing competition and increasing light availability, but that proximity to skid trails would negatively affect growth. A total of 300 sugar maples were sampled ∼10 years after selection harvesting in 18 stands in Témiscamingue (Québec, Canada). Detailed tree and skid trail maps were obtained in one 0.4 ha plot per stand. Square-root transformed radial growth data were fitted to a linear mixed model that included tree diameter, crown position, a neighbourhood competition index, light availability (estimated using the SORTIE light model), and distance to the nearest skid trail as explanatory variables. We considered various distance-dependent or -independent indices based on neighbourhood radii ranging from 6 to 12 m. The competition index that provided the best fit to the data was a distance-dependent index computed in a 6 m search radius, but a distance-independent version of the competition index provided an almost equivalent fit to data. Models corresponding to all combinations of main effects were fit to data using maximum likelihood, and weighted averages of parameter estimates were obtained using multimodel inference. All predictors had an influence on growth, with the exception of light. Radial growth decreased with increasing tree diameter, level of competition and proximity to skid trails, and varied among crown positions with trees in suppressed and intermediate positions having lower growth rates than codominants and dominants. Our results indicate that in selection managed stands, the radial growth of sugar maple trees depends on competition from close (≤6 m) conspecific neighbours, and is still affected by proximity to skid trails ∼10 years after harvesting. Such results underscore the importance of minimizing the extent of skid trail networks by careful pre-harvest planning of trail layout. We also conclude that the impact of heterogeneity among individual-tree neighbourhoods, such as those resulting from alternative spatial patterns of harvest, can usefully be integrated into models of post-harvest tree growth.     

Spatial impacts of soil disturbance and residual overstory on density and growth of regenerating aspen

We examined spatial aspects of harvesting impacts on aspen regeneration at 25 sites in northern Minnesota. These sites had been clearcut or partially harvested 4–11 years ago. At each site, residual overstory, which was composed of trees other than aspen, soil disturbance, and tree regeneration were determined along transects leading away from skid trails into the neighboring stand. We characterized spatial extent of soil disturbance as soil strength using an Eijkelkamp soil cone penetrometer. Soil disturbance dropped off very quickly at the edge of skid trails, suggesting that the impact of harvesting traffic on areas adjacent to skid trails is minor. On skid trails, disturbance levels were higher on sites harvested in summer than on sites harvested in winter. Even after adjustment for differences in soil disturbance, stands harvested in winter had higher regeneration densities and greater aspen height growth than stands harvested in summer, suggesting that aspen regeneration was more sensitive to a given level of soil disturbance on summer-harvested sites versus on winter-harvested sites. Soil disturbance and residual overstory interactively reduced aspen regeneration densities and height growth, indicating that avoidance of soil disturbance is even more critical in partially harvested stands. Predictions based in the spatial patterns of impact found in this study indicated that harvesting conditions may have a great impact in future productivity of a site.     

Enhancing the regeneration of compacted forest soils by planting black alder in skid lane tracks

Soil compaction due to the use of heavy machinery for timber harvesting has become a widespread problem in forestry. However, only few studies deal with the regeneration of compacted forest soils. In the present study, we examined the potential of accelerating soil regeneration by planting black alder trees (Alnus glutinosa (L.) Gaertn.) in skid lane tracks. In 2003, seedlings were planted into the rut beds of severely compacted skid lanes in two Swiss forest sites. In addition, some of the ruts were filled with compost. In 2009 and 2010, we assessed the success of these measures by analysing physical parameters of soil structure (bulk density, total and coarse porosity and air permeability), root densities and tree growth. Tree growth was exceptionally strong on the skid lanes. Total and coarse soil porosity and air permeability showed significant increase in planted skid lanes as compared to untreated control subplots, approaching values found for untrafficked soil in the immediate vicinity. All soil physical parameters were closely correlated to root mass density. Compost application enhanced tree growth and soil structure regeneration on one site, but had a retarding effect on the other site. Planting black alders has great potential as an environmentally friendly measure to accelerate the structural regeneration of compacted forest soils in temperate humid climates.