Accurate reconstruction of complex pavement surface textures is essential for reliable texture characterization and skid resistance evaluation. In this study, a three-dimensional point cloud correction method based on a quaternion rotation matrix was proposed to eliminate point cloud tilting and displacement caused by pavement slope and the initial orientation of the scanning equipment. A unified spatial rotation model was established to align the point cloud normal vector with the Z-axis while preserving the geometric rela-tionships among points. The method was validated using a pavement model with regular sharp textures and then applied to distressed pavements containing cracks, raveling, and rutting. The results showed that the proposed method more accurately reconstructed the original elevation features and effectively avoided the peak–valley blunting and texture smoothing associated with conventional profile-fitting correction. Compared with the conventional method, the average error of mean texture depth (MTD) was reduced by 48.3%, while the error of maximum texture elevation difference (Δh) remained within 39.9%. Statistical analysis indicated that the observed differences mainly resulted from the correction strategy rather than measurement uncertainty. The proposed method improves the accuracy of pavement texture reconstruction and texture parameter calculation and provides a reference for pavement evaluation and digital pavement modeling.

The crushed-rock interlayer highway embankment is widely used in cold regions to protect permafrost from degradation. However, current numerical calculation and indoor experiment methods have limitations in determining the convective cooling effect of the crushed rock structure. To address this, this study used the discrete element method to generate the model geometry and established a two-population Lattice Boltzmann Model. By analyzing the air velocity field and temperature field, it was determined that the factors such as porosity, block shape, void connectivity, block size, block arrangement form, and block thermal conductivity can influence the convective cooling effect. The study found that the convective cooling effect is highly dependent on the averaged air convection velocity inside the structure, and a large porosity should be maintained during the crushed rock interlayer construction. These findings provide a theoretical basis for future construction of crushed-rock interlayer embankments.

In low-temperature stable permafrost regions, both active and passive cooling measures are commonly employed to ensure the long-term stability of highway structures. However, despite adopting these measures, various types of structural issues caused by permafrost degradation remain prevalent in high-grade highways. This indicates that in addition to preventing permafrost melting, structural reinforcement of the foundation is still necessary. Based on the analysis of the long-term foundation temperature field and settlement using the finite element method, which was validated through an indoor top-down freeze–thaw cycle test, this paper explores, for the first time, the feasibility of applying geosynthetic-encased gravel pile composite highway foundations—previously commonly used for permafrost destruction—in low-temperature stable permafrost areas where permafrost protection is the primary principle. By analyzing the long-term temperature field, settlement behavior, and pile–soil stress ratios of permafrost foundations influenced by both the highway structure and composite foundation, it was found that when the pile diameter is 0.5 m, pile spacing is 2 m, and pile length is 11 m, the mean monthly ground temperature of the permafrost foundation will not be significantly affected. Therefore, the properly designed geosynthetic-encased gravel pile composite highway foundation can be adopted in low-temperature stable permafrost regions where permafrost protection, rather than destruction, is required.

A new method, the notched specimen cracking test (NSCT), is presented to directly measure the thermal stress and critical temperature of asphalt binders at low temperatures. The NSCT contains a notched specimen that contraction deformation is limited by special invar steel fixtures exposed to a continuous cooling temperature field provided by a programable environmental chamber. To simulate the actual thermal contraction state-strain level of asphalt pavement in the laboratory, the geometry of the binder specimen was carefully designed by theoretical computation based on the superposition principle. The preliminary test result shows that NSCT for evaluation of the potential cracking risk of modified or non-modified binders at low temperatures is reliable and easy to operate. The coefficient of variations of thermal stress results is at least 50% smaller than the traditional thermal cracking measurement method.

为研究风沙区公路护栏类型对积沙分布的影响,参照《公路交通安全设施设计细则》(JTG/T D81-2017)进行护栏建模,将沙粒看作流体中的流动粒子进行追踪,通过COMSOL Multiphysics 6.0软件进行模拟计算,以流体动力学理论为基础,以实测风速数据为计算参数,选择合适的曳力模型,研究三种常见护栏类型附近的流场分布状态和沙粒运动轨迹与沉积特性.结果表明:2021年5月15日至2022年5月15日之间,主导风向为SSW和SW,平均风速7.8m/s,5～10m/s风速占比79.23%;路基迎风侧坡脚处风速流场具有类似分布,迎风侧路肩形成风速加速区,背风侧均出现涡流区,风速低于2m/s;气流经路基边坡与混凝土护栏出现上扬,对沙粒具有抬升作用,抬升高度最高为15m;缆索护栏附近沙粒做类抛物线运动,在路基背风侧由于气流回流出现反方向运动;沙粒在波形梁钢护栏的气流影响下贴地滑动,在路面后半段沉积,且仅有波形梁钢护栏路面出现沙粒沉积,混凝土护栏与缆索护栏在路基背风侧坡脚出现沙粒沉积;依据缆索护栏附近沙粒抛物线运动高度推断,若风速减弱,沙粒仍会在路面沉积.

冻融循环和水损害侵蚀导致路面出现的大量裂纹成为目前西藏地区路面的主要病害,严重破坏了沥青路面的路用性能.玄武岩纤维沥青混合料是将沥青混合料和玄武岩纤维按一定配合比充分混合来增强沥青路面使用性能的复合型材料.其特点是根据玄武岩纤维的纤维增粘特性以及良好的阻裂性能.文章用玄武岩纤维沥青混合料来代替西藏地区常用AC-13沥青混合料,以玄武岩纤维掺量为研究对象进行冻融劈裂实验研究,以沥青混合料冻融强度比大小为衡量指标来探究玄武岩纤维在AC-13沥青混合料中最佳掺量.结果表明玄武岩纤维最佳掺量在0.2%～0.3%之间,在四种连续级配中0.3%的玄武岩纤维掺量的沥青混合料空隙率最小、冻融劈裂强度比最大,有利于阻止沥青路面裂缝的扩大、减少冻融循环劈裂现象的出现、对延长沥青路面的使用寿命和改善路用水平具有明显作用.

In southwest China,a large amount of solid waste such as tailings,coal gangue,waste rock,coal ash and so on is formed when mining minerals,which not only easily causes geological disasters in mines,but also causes great waste of mineral resources.In response to the national policy of accelerating the construction of ecological civilization and promoting the conser-vation and efficient utilization of mineral resources in the autonomous region,this paper takes Tanggula Mountain section of G109 National Highway as the research site,replaces the original base material with coal gangue and other waste slag,designs different mix ratios,and passes unrestricted compressive strength test,freeze-thaw compressive strength ratio test and erosion resistance test.To explore the feasibility of applying coal gangue to road base in Xizang area.The results show that the com-pressive strength of the base material can be increased and the cumulative brush amount of the specimen can be reduced by re-placing the natural stone with the appropriate amount of coal gangue.With the increase of coal gangue content,the ratio of freeze-thaw strength of the specimens increases on the whole.According to the analysis of the experimental results,the optimal mix ratio is m(cement)∶m(lime)∶m(fly ash)∶m(coal gangue)∶m(crushed stone)=2∶10∶38∶35∶15.

In order to investigate the contact behaviours of tire-pavement under dry condition, the finite element method was applied to establish the numerical model of the tire Bridgestone 205-55-R16 and textured asphalt pavement model . Based on the contact mechanics for elastic pavement, the contact model of three-dimensional tire-asphalt pavement was established according to Lagrangian algorithm. By considering the influence of pavement texture, the friction subroutine was compiled to calculate the tire-pavement adhesion coefficient. The influence of internal inflation pressure and wheel load on contact characteristics of tire-asphalt pavement were discussed respectively under static load and antilock braking system (ABS) state. The results show that when the slip rate is around 15%, the longitudinal adhesion coefficient of the tire reaches the maximum, which is in accordance with the setting of tire adhesion coefficient in tire science. When the tire is in emergency braking, the tire shoulder position and tread centre area are more susceptible to wear, and the contact pressure in centre area is biggest. Under the same wheel load and internal inflation pressure, the mean contact pressure increases by 8.4% and the contact area reduces by 7.7% when tire is at ABS state compared with the condition of static load.

To clarify the intrinsic relationship between the mechanical properties of asphalt and its fraction composition, the SARA fraction composition and six macroscopic mechanical properties (critical cracking temperature (TCR), fatigue life (Nf), non-recoverable creep (Jnr3.2), penetration, ductility, and softening point) were investigated for 16 asphalt samples. Fraction contents of asphaltene and aromatic are strongly correlated with TCR and ductility (R2 > 0.92) that characterize the ability of asphalt to adapt to deformation at low and medium temperatures. Heavy fraction (asphaltene and resins) content is also strongly correlated with (R2 > 0.90) penetration and Jnr3.2 that characterize the resistance of the asphalt to overall deformation at medium and high temperatures. To express the changes in the four fractions simultaneously with one indicator, a statistic, average deviation of the fractions between the given asphalt and its original (marked σ), is introduced in this study to characterize the degree of asphalt aging based on the fraction changes. It normalizes the four simultaneous change indicators (percentage of SARA fractions) during asphalt aging into one indicator. This new indicator has a strong correlation with several mechanical performance indicators of asphalt, where it is strongly correlated with TCR (R2 > 0.90), ductility, and penetration, which are also well correlated with Jnr3.2 (R2 > 0.85), Nf (R2 > 0.75), and softening point (R2 > 0.75).

西藏地区灾害类型多,高山深谷区断裂活动强,河床侵蚀和淤积作用强,崩塌及山体滑坡等现象频繁出现,成灾率高、影响范围广.西藏的公路较长,若一处受灾则可能造成运输中断,甚至导致交通瘫痪.这些灾害严重威胁着当地居民和外来游客的生命安全.基于以上情况,以信息共享为切入点,设计并实现了基于Windows的安全出行软件.文章首先对西藏境内各国道、省道及公路沿线的边坡进行地质勘察与评估,从而设计出以灾害防治为核心,服务于驾驶人员、路政部门、政府及沿线居民的多功能安全服务软件.该平台以较低的成本获取灾害信息并及时反馈给路政交通部门和沿线政府,使其提前做好公路沿线的灾害防治工作,切实保证村民及驾驶人员的生命财产安全.

多年冻土区的沥青公路病害类型与沥青面层温度场密切相关.为探究路面温度场的分布规律,在国道G109安多-唐古拉山段K3357处(海拔5 231 m)建立观测点,包括在沥青路面面层不同深度埋设ZDR系列温度记录仪,在路旁架设TRM-ZS2气象站,对路面不同深度的温度、环境温度、太阳辐射、相对湿度、风速等进行连续跟踪,采用多元回归法分析路面温度场与气象因素之间的关系.结果 表明:随着路面深度的增加,温度波动范围逐渐变小;温度场与气温和太阳辐射皆呈正相关、与相对湿度和风速相关性较低;气温是影响温度场的最主要因素,太阳辐射仅在9～21时对温度场具有影响作用;气温与太阳辐射对温度场的影响分别具有1.5小时和2.5小时的滞后性.

波密县地处西藏东南部,地貌地质环境特殊,滑坡灾害频发。本文选取地层岩性、边坡高度、边坡角度、坡面走向、水系距离和植被覆盖度作为评价因子,通过Arc GIS提取滑坡灾害评价因子相关数据,并利用C4.5算法建立的决策树分类模型对研究区域滑坡灾害的风险性进行了定量评估。结果表明:该模型总体预测精度达到89.7%,有效预测精度高达96.2%。表明该模型具有较高的精度和置信度,为波密县滑坡灾害的预测性分析提供参考。

Sand slide slope are sudden, unpredictable and has great harm.Through field investigations around Lhasa, 12 representative data sets of sand slide slope disaster points were collected. By combining Bayesian network and Particle Swarm Optimization algorithm, and using algorithm update formula to make up for the short comings of the single algorithm, information entropy was introduced to analyze the weight of rainfall, slope, slope height and vegetation coverage in the algorithm.Then, the influence of various factors on the stability of sand-pass slope is analyzed and the stability of sand-pass slope is graded. Experiments proved that the method is effective and has certain reference value for the stability evaluation of sand slide slope.

"新工科"建设背景下,西藏自治区传统工科如何适应快速发展的社会需求,培养出更多的工科创新应用型人才成为亟待解决的问题.以西藏大学土木工程专业为例,总结了该专业的现状及存在的问题,在论述"新工科"带来的挑战与机遇的基础上,提出了适应"新工科"建设要求的土木工程专业发展策略,旨在提高西藏大学土木工程专业的人才培养质量,并为西藏自治区高校的土木工程专业改革提供借鉴.

In this study, the underlying causes of the performance degradation of three typical waste-oil rejuvenated asphalts (i.e., asphalts rejuvenated by waste cooking oil (WCO), waste bio-oil (WBO), and waste engine oil (WEO)) after secondary aging are explored via SARA fractions analysis. The rejuvenation provided by WCO is found to be mainly based on supplementing aged asphalt with saturates, which causes the newly formed colloids to easily lose light components and exhibit low stability. Further, WEO contains some metal residues that catalyze the oxidation and polycondensation process of asphalt. Consequently, the performance of the asphalts rejuvenated separately by WCO and WEO is severely degraded during aging. By contrast, WBO has a stable colloidal structure and lacks ashes; thus, WBOrejuvenated asphalt exhibits the most stable and reasonable performance degradation in the aging process. Our research suggests that the effect of rejuvenation on aged asphalt cannot be judged only by the difference between the performances of the rejuvenated asphalt and the original asphalt. The performance maintenance of the rejuvenated asphalt during the secondary aging process requires further investigation. (c) 2021 Elsevier Ltd. All rights reserved.

建设大学生开放实验室是提高本科教育质量的重要途径.对目前国内开放实验室常见的问题进行了总结,将其统一归纳为弱约束现象.在对弱约束现象产生的原因进行分析后,针对性地提出了一种改进模式——弱约束下的强管理教育模式,对实验室运行过程中的管理模式、制度、考核办法等多个方面提出了具体措施.该模式在应用于西藏大学工学院某实验室后,该实验室的学科竞赛获奖数、大创项目立项数和论文发表数等均有显著增加.实践表明,对大学生开放实验室弱约束强管理,可充分发挥大学生开放实验室的功效.

The traditional method for determining mixing and compaction temperatures of asphalt binders, such as Brookfield viscosity test, often yields excessively high temperatures when used in many modified asphalts, and underestimates the temperature decreasing effect of the additives when used in warm-mixing asphalts. This study proposed a new viscosity measurement method, namely rotational plate viscosity (RPV) testing, to overcome these issues. The new method uses a Dynamic Shear Rheometer (DSR) with a 25-mm-diameter parallel plate geometry and a fixed shear rate 40 s-1 to measure the viscosity-temperature curve of modified asphalts, which minimizes the effect of the shear-thinning behavior. In addition, there are two main advantages of this new method. First, it can be carried out using an existing standard DSR machine typically used in most asphalt binder laboratories. Second, it can greatly improve the accuracy and efficiency of testing with sophisticated sensors and programmed settings.

西藏经济发展离不开各行各业人才的不断输入,特别是适应当地人文环境和自然环境的应用型人才,高质量人才需求的不断增加促使西藏本地的工程教育需要快速发展.文章在分析西藏现有工程教育的基础上,提出通过加强高校与高校、政府、研究院所、企业之间的联系解决制约西藏工程教育发展的相关问题,特别是如何充分发挥社会和学校资源,组建利益共同体,协同各方面人才培养要素,以及充分利用信息技术建立跨单位协同育人的桥梁,促进西藏工程教育的健康、可持续发展.

沥青的紫外线老化问题一直是西藏各地沥青道路老化开裂的主要原因之一.紫外线会促使沥青发生氧化聚合反应,使沥青质增加胶质减少,从而导致沥青老化变脆,在车载下开裂.为了解决沥青的紫外线老化问题,文章提出通过掺如蒙脱土来提高沥青的抗氧化性.根据不同掺量SBS沥青的三大指标可知,蒙脱土可以改善沥青的内部黏性,维持内部物质均衡.在不同紫外线照射时长下各组沥青三大指标变化可知,蒙脱土掺量越高,抗紫外线老化越好,掺量为2％时,沥青的抗紫外线老化效果变化最明显.

落石是西藏山区公路周边最常见的地质灾害之一,严重威胁人们的出行安全.落石具有冲击力大、运动范围广的特点.针对落石的冲击破坏特性,文章介绍了一种导向式落石防护装置.根据落石自由落体运动及冲击力模型得出落石冲击力大小的影响因素,并以导向作用模型阐释冲击碰撞过程中落石、闸板的运动转换以及装置的受力情况.最后以模型推论为基础,实例说明该装置针对不同大小的落石的导向运动方式.