生态敏感区道路建设的生态效应量化评估是平衡基础设施发展与生态保护的主要挑战,但现有研究在揭示线性工程复杂生态效应的时空异质性及其定量表征方面仍存在不足。首次基于“关键指标+动态参照系”提出路域生态指数(Road Area Ecologic...生态敏感区道路建设的生态效应量化评估是平衡基础设施发展与生态保护的主要挑战,但现有研究在揭示线性工程复杂生态效应的时空异质性及其定量表征方面仍存在不足。首次基于“关键指标+动态参照系”提出路域生态指数(Road Area Ecological Index,RAEI),通过整合生态系统“结构-质量-功能”三维度,创新性引入“历史条件”(时间维度演变)与“极小干扰”(空间基准状态)双尺度动态参照系,构建适用于生态敏感区的道路生态效应评估框架,融合道路施工资料与多模态遥感数据,选取青藏高原同赛高速,进行生态效应的定量评估。研究发现:(1)RAEI通过纳入景观格局指标(斑块内聚力、景观多样性)提升了对线性路域生态效应的综合表征能力,定量揭示了绿色道路段(技术措施实施区)较传统道路段在降低负面生态效应上的差异性;(2)不同路域影响区生态效应呈现显著空间分异:在0—100m核心影响区,绿色道路1段表现出0.025的正面效应,而绿色道路2段和传统道路段的负面效应量分别为0.084和0.074;在100—1000m缓冲带,绿色道路2段的负面效应量始终小于传统道路段;(3)不同区域道路生态效应存在空间异质性:生态本底较为脆弱的绿色道路1段,在实施生态护坡与植被快速恢复等技术后呈现正向保护效应,而绿色道路2段灌丛集群区和高海拔区域及传统道路段等关键敏感点位表现为负面效应,且效应量集中于0.08值域内,表明高寒区植被恢复措施具有周期滞后响应特征。本研究提出的多维评估框架,为生态敏感区道路修建提供了可移植的生态风险评估工具,为道路优化施工、生态保护修复和区域高质量发展提供重要的科学支撑。展开更多
In the evaluation of road roughness and its effects on vehicles response in terms of ride quality, loads induced on pavement, drivers＇ comfort, etc., it is very common to generate road profles based on the equation p...In the evaluation of road roughness and its effects on vehicles response in terms of ride quality, loads induced on pavement, drivers＇ comfort, etc., it is very common to generate road profles based on the equation provided by ISO 8608 standard, according to which it is possible to group road surface profiles into eight different classes. However, real profiles are significantly different from the artificial ones because of the non-stationary fea- ture of the first ones and the not full capability of the ISO 8608 equation to correctly describe the frequency content of real road profiles. In this paper, the international roughness index, the frequency-weighted vertical acceleration awz according to ISO 2631, and the dynamic load index are applied both on artificial and real profiles, highlighting the different results obtained. The analysis carried out in this work has highlighted some limitation of the ISO 8608 approach in the description of performance and conditions of real pavement profiles. Furthermore, the different sensitivity of the various indices to the fitted power spectral density parameters is shown, which should be taken into account when performing analysis using artificial profiles.展开更多
Generally, mine roads are located in the mountain areas, as its complex topography, mostly along the river near the cliffs, steep bend anxious, the mine road design has to adopt lower technical standards relatively an...Generally, mine roads are located in the mountain areas, as its complex topography, mostly along the river near the cliffs, steep bend anxious, the mine road design has to adopt lower technical standards relatively and usually is lack of traffic safety facilities. Especially, there are mainly medium-sized vehicles on mine road, under the heavy traffic vehicles affect repeatedly, high frequency of traffic accidents more easily happen in mine road area and cause serious effects on life or property. Combining with the particularity of mine road safety environment, this paper studies the basic theory of safety evaluation, analyses the factors of traffic safety design and special mine terrain conditions, and then establishes mine road safety index system and evaluation model based on the principles such as systematicness, independent indexes, qualitative and quantitative analysis, feasibility, scientificity and reliability. At last, the paper successfully evaluates the safety of road in Huang Mailing phosphate rock area with fuzzy AHP method based on engineering project.展开更多
The native soil behavior of unpaved low volume roads and their mode of failure were studied to establish proper method of stabilizing native soils using local available materials. The use of lime and its positive effe...The native soil behavior of unpaved low volume roads and their mode of failure were studied to establish proper method of stabilizing native soils using local available materials. The use of lime and its positive effect to modify and stabilize Ngara soil in Tanzania is presented in this paper. There are many methods of stabilizing soil to gain required engineering specifications. These methods range from mechanical to chemical stabilization. Most of these methods are relatively expensive to be implemeted by slowly developing nations and the best way is to use locally available materials with relatively cheap costs affordable by their internal funds. Tanzania is a country having abundantly amount of Lime. Ngara native soil roads (unpaved rural roads) was studied under preliminary investigation and found to have higher plasticity, tendency of swelling and shrinking, low bearing capacity when wet, compressive strength of soil to have higher sensitivity to moisture and lower shear strength when wet. These soil behaviors deny road access to about 32 million people in Tanzania (80% of population) during rainy season. The detailed investigations is still going on at China university of Geosciences but other results from similar researches show that Ngara soils can be stabilized by lime and gain the required engineering properties.展开更多
The objective of this work is to obtain a composite of clay-cement-metakaolin having good mechanical properties and geotechnical. To do this, a lateritic clay from Burkina Faso referenced ALK was characterized by vari...The objective of this work is to obtain a composite of clay-cement-metakaolin having good mechanical properties and geotechnical. To do this, a lateritic clay from Burkina Faso referenced ALK was characterized by various methods (X-ray diffraction, infrared spectrometry, thermal analysis and Inductively Coupled Plasma, Atomic Emission Spectrometry) in order to be used as a base course after adding cement and metakaolin. The results of the mineralogical characterization of this clay showed that it is composed of kaolinite (65.7 wt.%), quartz (19.3 wt.%) and goethite (10.8 wt.%). The geotechnical tests carried out showed that ALK is moderately plastic with a plasticity index Ip = 22%. The optimum moisture content and the maximum dry density are respectively 15.9% and 1.76 g∙cm<sup>-3</sup>. Simple compressive strength and splitting tensile strength are Rc = 1.59 MPa and ft = 0.149 MPa respectively. The California Bearing Ratio (CBR) index at 95% is 40% and above the minimum value of 30% shows that ALK can be used as a sub-base course in road construction. The addition of cement and metakaolin in various proportions improved the CBR index and the mechanical strength of the composites produced. This improvement is due to the formation of hydrated calcium silicate (CSH) resulting from the pozzolanic reaction between the portlandite of the cement and the amorphous silica of the metakaolin. Thus the 2 wt.% metakaolin and 6 wt.% cement formulation with a 95%CBR index of 81% is suitable for the development of a base course in road construction.展开更多
The phenomenological equations of motion for the international roughness index (IRI) have been reviewed and discussed in terms of Lagrangian method in physics. The current paper proposes a practical, two-dimensional m...The phenomenological equations of motion for the international roughness index (IRI) have been reviewed and discussed in terms of Lagrangian method in physics. The current paper proposes a practical, two-dimensional model for studying essentially three-dimensional, vibrating,?and?mechanical systems (vehicles). The purpose is to provide a new profiling method for IRI, which is practical in computations and compatible with traditional profiling for roughness of a road-surface. The modern technology employs elaborated sensors such as gyro sensor, Global Positioning System (GPS), magnetometer sensor,?and?accelerometer to measure high-speed longitudinal motions, resulting in time series of big-data expressed as compressed longitudinal spikes. The time series of longitudinal spikes obtained from high-speed longitudinal motions are traditionally considered as a background noise for constructing a profile. The conventional IRI is calculated from big-data of the road profile by employing statistical method, but the Lagrangian model dynamically determines the road profile. The useful concept and relation among the road-roughness function?, associated roughness index (ARI), acceleration and position are introduced and examined in the present paper. The associated roughness index (ARI) defined by the current dynamical approach is examined by applying virtual simulations which represent roughness of a road-surface. The current theoretical model supports and compensates information of interpreting a profile of IRI and elucidates physical meanings for the roughness index of a road-surface.展开更多
近年来,基于位置服务的技术迅猛发展,产生了海量的路网轨迹数据。而路径范围查询作为一种路网轨迹查询类型,是支持其他查询类型的基础。为了实现对海量路网轨迹数据的高效索引,同时提供精确的路径范围查询服务,提出了一种基于道格拉斯-...近年来,基于位置服务的技术迅猛发展,产生了海量的路网轨迹数据。而路径范围查询作为一种路网轨迹查询类型,是支持其他查询类型的基础。为了实现对海量路网轨迹数据的高效索引,同时提供精确的路径范围查询服务,提出了一种基于道格拉斯-普克算法的学习型索引结构(Douglas-Peuker Based Learned Index Structure,DPLI)。首先将轨迹数据分为多个轨迹段,然后取轨迹段中的点作为轨迹数据的表征,利用映射函数将其映射为一维映射值序列,而后根据键值数量将其划分为多个数据分片。在分片内将首尾数据组成一条线段,然后计算其余数据点距离线段的拟合误差,将超过误差阈值的数据点作为新的线段端点,递归分割原有的直线段,直到所有数据点的拟合误差小于阈值,从而拟合分段线性函数。采用多个路网数据和轨迹数据进行了充分的实验,实验结果表明:与传统索引方法相比,DPLI具有更快的构建效率和磁盘访问效率;与学习索引方法相比,DPLI保持了构建效率的优势,并且达到了100%查询召回率。展开更多
文摘生态敏感区道路建设的生态效应量化评估是平衡基础设施发展与生态保护的主要挑战,但现有研究在揭示线性工程复杂生态效应的时空异质性及其定量表征方面仍存在不足。首次基于“关键指标+动态参照系”提出路域生态指数(Road Area Ecological Index,RAEI),通过整合生态系统“结构-质量-功能”三维度,创新性引入“历史条件”(时间维度演变)与“极小干扰”(空间基准状态)双尺度动态参照系,构建适用于生态敏感区的道路生态效应评估框架,融合道路施工资料与多模态遥感数据,选取青藏高原同赛高速,进行生态效应的定量评估。研究发现:(1)RAEI通过纳入景观格局指标(斑块内聚力、景观多样性)提升了对线性路域生态效应的综合表征能力,定量揭示了绿色道路段(技术措施实施区)较传统道路段在降低负面生态效应上的差异性;(2)不同路域影响区生态效应呈现显著空间分异:在0—100m核心影响区,绿色道路1段表现出0.025的正面效应,而绿色道路2段和传统道路段的负面效应量分别为0.084和0.074;在100—1000m缓冲带,绿色道路2段的负面效应量始终小于传统道路段;(3)不同区域道路生态效应存在空间异质性:生态本底较为脆弱的绿色道路1段,在实施生态护坡与植被快速恢复等技术后呈现正向保护效应,而绿色道路2段灌丛集群区和高海拔区域及传统道路段等关键敏感点位表现为负面效应,且效应量集中于0.08值域内,表明高寒区植被恢复措施具有周期滞后响应特征。本研究提出的多维评估框架,为生态敏感区道路修建提供了可移植的生态风险评估工具,为道路优化施工、生态保护修复和区域高质量发展提供重要的科学支撑。
文摘In the evaluation of road roughness and its effects on vehicles response in terms of ride quality, loads induced on pavement, drivers＇ comfort, etc., it is very common to generate road profles based on the equation provided by ISO 8608 standard, according to which it is possible to group road surface profiles into eight different classes. However, real profiles are significantly different from the artificial ones because of the non-stationary fea- ture of the first ones and the not full capability of the ISO 8608 equation to correctly describe the frequency content of real road profiles. In this paper, the international roughness index, the frequency-weighted vertical acceleration awz according to ISO 2631, and the dynamic load index are applied both on artificial and real profiles, highlighting the different results obtained. The analysis carried out in this work has highlighted some limitation of the ISO 8608 approach in the description of performance and conditions of real pavement profiles. Furthermore, the different sensitivity of the various indices to the fitted power spectral density parameters is shown, which should be taken into account when performing analysis using artificial profiles.
文摘Generally, mine roads are located in the mountain areas, as its complex topography, mostly along the river near the cliffs, steep bend anxious, the mine road design has to adopt lower technical standards relatively and usually is lack of traffic safety facilities. Especially, there are mainly medium-sized vehicles on mine road, under the heavy traffic vehicles affect repeatedly, high frequency of traffic accidents more easily happen in mine road area and cause serious effects on life or property. Combining with the particularity of mine road safety environment, this paper studies the basic theory of safety evaluation, analyses the factors of traffic safety design and special mine terrain conditions, and then establishes mine road safety index system and evaluation model based on the principles such as systematicness, independent indexes, qualitative and quantitative analysis, feasibility, scientificity and reliability. At last, the paper successfully evaluates the safety of road in Huang Mailing phosphate rock area with fuzzy AHP method based on engineering project.
文摘The native soil behavior of unpaved low volume roads and their mode of failure were studied to establish proper method of stabilizing native soils using local available materials. The use of lime and its positive effect to modify and stabilize Ngara soil in Tanzania is presented in this paper. There are many methods of stabilizing soil to gain required engineering specifications. These methods range from mechanical to chemical stabilization. Most of these methods are relatively expensive to be implemeted by slowly developing nations and the best way is to use locally available materials with relatively cheap costs affordable by their internal funds. Tanzania is a country having abundantly amount of Lime. Ngara native soil roads (unpaved rural roads) was studied under preliminary investigation and found to have higher plasticity, tendency of swelling and shrinking, low bearing capacity when wet, compressive strength of soil to have higher sensitivity to moisture and lower shear strength when wet. These soil behaviors deny road access to about 32 million people in Tanzania (80% of population) during rainy season. The detailed investigations is still going on at China university of Geosciences but other results from similar researches show that Ngara soils can be stabilized by lime and gain the required engineering properties.
文摘The objective of this work is to obtain a composite of clay-cement-metakaolin having good mechanical properties and geotechnical. To do this, a lateritic clay from Burkina Faso referenced ALK was characterized by various methods (X-ray diffraction, infrared spectrometry, thermal analysis and Inductively Coupled Plasma, Atomic Emission Spectrometry) in order to be used as a base course after adding cement and metakaolin. The results of the mineralogical characterization of this clay showed that it is composed of kaolinite (65.7 wt.%), quartz (19.3 wt.%) and goethite (10.8 wt.%). The geotechnical tests carried out showed that ALK is moderately plastic with a plasticity index Ip = 22%. The optimum moisture content and the maximum dry density are respectively 15.9% and 1.76 g∙cm<sup>-3</sup>. Simple compressive strength and splitting tensile strength are Rc = 1.59 MPa and ft = 0.149 MPa respectively. The California Bearing Ratio (CBR) index at 95% is 40% and above the minimum value of 30% shows that ALK can be used as a sub-base course in road construction. The addition of cement and metakaolin in various proportions improved the CBR index and the mechanical strength of the composites produced. This improvement is due to the formation of hydrated calcium silicate (CSH) resulting from the pozzolanic reaction between the portlandite of the cement and the amorphous silica of the metakaolin. Thus the 2 wt.% metakaolin and 6 wt.% cement formulation with a 95%CBR index of 81% is suitable for the development of a base course in road construction.
文摘The phenomenological equations of motion for the international roughness index (IRI) have been reviewed and discussed in terms of Lagrangian method in physics. The current paper proposes a practical, two-dimensional model for studying essentially three-dimensional, vibrating,?and?mechanical systems (vehicles). The purpose is to provide a new profiling method for IRI, which is practical in computations and compatible with traditional profiling for roughness of a road-surface. The modern technology employs elaborated sensors such as gyro sensor, Global Positioning System (GPS), magnetometer sensor,?and?accelerometer to measure high-speed longitudinal motions, resulting in time series of big-data expressed as compressed longitudinal spikes. The time series of longitudinal spikes obtained from high-speed longitudinal motions are traditionally considered as a background noise for constructing a profile. The conventional IRI is calculated from big-data of the road profile by employing statistical method, but the Lagrangian model dynamically determines the road profile. The useful concept and relation among the road-roughness function?, associated roughness index (ARI), acceleration and position are introduced and examined in the present paper. The associated roughness index (ARI) defined by the current dynamical approach is examined by applying virtual simulations which represent roughness of a road-surface. The current theoretical model supports and compensates information of interpreting a profile of IRI and elucidates physical meanings for the roughness index of a road-surface.
文摘近年来,基于位置服务的技术迅猛发展,产生了海量的路网轨迹数据。而路径范围查询作为一种路网轨迹查询类型,是支持其他查询类型的基础。为了实现对海量路网轨迹数据的高效索引,同时提供精确的路径范围查询服务,提出了一种基于道格拉斯-普克算法的学习型索引结构(Douglas-Peuker Based Learned Index Structure,DPLI)。首先将轨迹数据分为多个轨迹段,然后取轨迹段中的点作为轨迹数据的表征,利用映射函数将其映射为一维映射值序列,而后根据键值数量将其划分为多个数据分片。在分片内将首尾数据组成一条线段,然后计算其余数据点距离线段的拟合误差,将超过误差阈值的数据点作为新的线段端点,递归分割原有的直线段,直到所有数据点的拟合误差小于阈值,从而拟合分段线性函数。采用多个路网数据和轨迹数据进行了充分的实验,实验结果表明:与传统索引方法相比,DPLI具有更快的构建效率和磁盘访问效率;与学习索引方法相比,DPLI保持了构建效率的优势,并且达到了100%查询召回率。
