昆石高速公路K22滑坡稳定的离散元分析

昆明—石林高速公路(简称昆石公路)松茂滑坡位于K22+900~K23+180段。为确保该路段安全,对K22段滑坡进行抗滑桩处治。为了检验处治方案的合理性,利用离散元元模拟了滑坡处治前后的边坡稳定状况。离散元元分析结果表明,处治前的滑坡情况和现场实际情况比较吻合。对K22+900滑坡段施加抗滑桩的处治后的模拟结果表明,处治后的滑坡安全、稳定。     

斜坡体上路堤抗滑稳定技术研究

结合重庆江津长江公路大桥南引道K7 840～K7 993．5路段滑坡处治工程实例，主要研究在山区斜坡体上修筑高等级公路路堤时，容易产生的工程滑坡灾害现象及相应的处治技术。     

浦合公路红砂岩路堑边坡滑坡处治分析

针对红砂岩地质易风化、崩解,遇水软化的特征,结合浦合公路K12+785～K13+300段滑坡处治工程,分析红砂岩路堑边坡滑坡原因,经过对边坡稳定性进行分析、评价,提出红砂岩边坡滑坡处治方案,并提出红砂岩地质条件下路基边坡设计和施工建议。     

G217线独-库公路K777+518～K777+629段滑坡病害分析

简要介绍了"国道217线独-库公路K777+518～K777+629段滑坡"的自然地理、工程地质条件,对该段滑坡进行了特征研究和稳定性评价,并初步提出了处治措施.     

甬金高速公路滑坡段稳定性分析及治理设计

结合工程地质条件和试验资料,对甬金高速公路K107+300~K107+450滑坡段和滑坡段前后方各100m路段边坡的稳定性进行评价,进而提出滑坡的治理设计,确定了以抗滑桩为主,地表排水、地下排水和边坡防护工程为辅的处治方案。     

临吉高速公路东团滑坡稳定性分析与处治措施研究

在工程地质勘察和数值计算的基础上,分析了临吉高速公路K220+700~K220+960段路堑边坡的工程地质条件、滑坡产生原因,对滑坡进行稳定性分析。研究表明:坡体存在顺层的软弱岩层是该滑坡产生的内因,降雨入渗、路基全断面开挖及支护不及时是该边坡滑坡的诱因。强度折减法计算表明,目前边坡的稳定系数为0.963,处于不稳定状态,需要处治。针对滑坡的特点及工程环境条件,提出了临时反压、抗滑桩等支挡结构为主,排水、坡面防护为辅的综合处治措施,实践证明该处治方案安全可靠,具有一定借鉴意义。     

某高速公路填方路基滑坡成因及稳定性分析

以某高速公路K128+240—K128+633段高填路基滑坡为例，结合工程区地形地貌条件、水文地质条件、人类工程活动等，分析了该滑坡的变形破坏特征和成因机理，认为该滑坡的形成是由多种因素共同作用的结果，地层岩性是滑坡形成的基础，大气降雨及人类工程活动是滑坡形成的诱因。通过稳定性分析与计算，采用锚索+抗滑桩、截排水等措施对滑坡进行了综合处理，目前该滑坡已处于稳定状态，处治措施达到了良好的效果。     

某收费站管理场区边坡滑坡原因分析及处治设计

结合工程的自然地质条件、水文地质条件和人类工程活动等,分析了某高速公路收费站管理场区在边坡开挖时诱发滑坡的变形特征和形成机理,通过稳定性计算分析,最终采用调整场区位置+反压回填+抗滑桩的综合处治方案对滑坡进行处治,该滑坡目前已处于稳定状态,达到了处治目的,取得了较好的工程处治效果。     

某高速公路边坡滑坡分析及处治设计

以某高速公路边坡滑坡处治为依托,结合其工程地质、水文条件及现场实际情况,分析了滑坡的变形特征和滑动机理,并对其进行稳定性计算分析,根据计算分析结果进行处治方案比选设计,最终采用钢花管注浆+预应力锚索的综合处治方法对滑坡进行处治,取得了较好的工程处治效果,可为同类工程提供参考。     

某公路滑坡灾害成因分析与防治对策

吉县至河津高速公路K29+650~K29+900段滑坡对公路建设带来严重影响,对其成因进行分析并提出防治对策具有紧迫性。从地形地貌条件、气象条件、地层岩性条件、地质构造与地震条件和水文地质条件方面分析该滑坡的孕灾环境,通过对滑坡成因的分析,可知该滑坡的运动形式以推移式为主,土体结构、人类工程活动及大气降水是影响滑坡稳定性的主要因素,采用中上部卸载、抗滑桩设计、落水洞回填处治、加强排水、路基裂缝及地表裂缝处治、涵洞加固等对滑坡进行处治。     

水及水蒸气对YBa_2Cu_3O_(7-x)相结构及超导电性的影响

以热重分析(TGA)、X 射线衍射及电阻-温度关系测定等方法,研究了水及水蒸气于285-1223K 间对 YBa_2Cu_3O_(7-x)超导材料的超导电性退化、水解及热重变化等过程的影响.YBa_2Cu_3O_(7-x)试样在水及水蒸气冷凝于试样表面的水膜的作用下,将逐渐水解为 BaCO_3、CuO 及 Y_2O_3等产物.当试样或水蒸气的温度高于373K 时,水蒸气对YBa_2Cu_3O_(7-x)的晶体结构与超导电性无明显影响.在20%H_2O+80%O_2的气体介质中,YBa_2Cu_3O_(7-x)于373-1223K 问的 TGA 曲线与在常压大气中相似,其放-吸氧及相变过程是完全可逆的.自1223K 降温至373K,YBa_2Cu_3O_(7-x)恢复原来结构与性能.     

The influence of Laval nozzle throat size on supersonic molecular beam injection

In this study, finite element analysis （FEA） has been used to investigate the effects of different Laval nozzle throat sizes on supersonic molecular beam. The simulations indicate the Mach numbers of the molecular stream peak at different positions along the center axis of the beam, which correspond to local minimums of the molecular densities. With the increase of the throat diameter, the first peak of the Mach number increases first and then decreases, while that of the molecular number density increases gradually. Moreover, both first peaks shift progressively away from the throat. At the last part, we discuss the possible applications of our FEA approach to solve some crucial problems met in modern transportations.     

换填与降排水措施对寒区沟谷软弱路基冻结特征的影响

基于甘肃南部宕昌-迭部二级公路, 选取了2个典型寒区沟谷软土路基试验段, 监测了2个冻融期内路基温度、含水量、变形以及地下水位, 分析了弃渣换填深度与降排水措施对路基冻结特征的影响。分析结果表明: 在监测的2个冻结期内, 换填深度为2.0m的试验段K18+180的冻结深度比换填深度为1.0m的试验段K18+330的冻结深度大0.12~0.16m, 说明换填深度越大, 冻结深度越大; K18+330段初始地下水位为3.4m, 仅设置地表排水沟时, 冻结期间地下水位稳定在3.4m左右, 距冻结面的最小距离为1.7m, 说明设置排水沟时地下水位在冻结期间基本没有变化; K18+180段初始地下水位是1.3m, 在设置了渗沟降水措施后, 冻结期间地下水位稳定在2.0m左右, 距冻结面的最小距离为0.2m, 地下水位降低了约0.7m, 因此, 渗沟降水可以降低地下水位, 防止路基冻胀; K18+180段路基中心2个周期监测的最大冻胀分别为3.4、4.2mm, 而K18+330段相应位置的最大冻胀分别为10.7、14.0mm, 后者均是前者的3倍多, 说明换填深度越大路基冻胀越小; 《公路路基设计规范》 (JTG D30—2015) 规定的二级公路容许冻胀为50mm, 软土路基容许工后沉降为500mm, K18+180、K18+330段路基的最大沉降分别为1.5、1.8mm, 最大冻胀分别为4.2、14.0mm, 远远小于规范值, 表明试验段路基的稳定性良好, 采用换填与降排水措施能有效控制路基冻胀。      

DC and AC transport properties on La0.8Sr0.2MnO3

Magnetoresistive sensor can be widely used in modem transportation field, such as the vehicle positioning and navigation system, vehicle detection system, and intelligent transportation system. In order to improve the efficiency of magnetoresistive sensor, we synthesized Lao.sSro.2MnO3 polycrystalline bulks at different sintering temperatures and investigated their DC and AC transport properties in this work. As a result, all samples showed insulator-metal （I-M） phase transition, and the transition temperature （TI-M） shifted to higher temperature with the increase of sintering temperature. The TI-M measured at different AC frequencies was smaller than that measured at DC condition, which implied that the I-M phase transition was suppressed at AC frequencies. The resistivity mea- sured at high AC frequencies was larger than that measured at low AC frequencies, which could be attributed to the change of the magnetic penetration depth （6）. However, the room-temperature AC-magnetoresistance （MR） at low frequencies was much larger than that at high frequencies and room-temperature DC-MR. These findings demon- strate that reducing the AC frequency is an effective way for enhancing the room-temperature MR, which can be used to promote the efficiency of magnetoresistive sensor.     

川藏公路田妥—怒江段某滑坡稳定性分析与整治

结合国道318线川藏公路田妥一怒江段K3668+700～K3668+790滑坡的基本状况,对滑坡的成因进行了分析。对K3668+715断面建立了有限元分析模型,利用有限元强度折减法,计算分析了该段滑坡在重力场和地震作用下的稳定性,计算分析求得该滑坡整治前在重力场和地震作用下的稳定安全系数分别为0.99和0.93,滑坡处于不稳定的滑动状态,应及时对该段滑坡进行整治。提出了合理的整治方案并进行了安全性评价,结果表明整治后滑坡的安全系数大于设计安全系。     

A multi-scale point of view on the structure-property relationships of A15 superconductors

Nb3Sn and other A15 members have been widely applied in nuclear power, nuclear magnetic resonance, and high-energy particle accelerators for their high critical current density （Jc） and upper critical field （Bc2）. There have been comprehensive and intensive studies on the applications, the fundamental lattice dynamic and electronic properties, etc., of A15 superconductors. Various reviews on the preparations, structures, and properties have already been written in the last few years. Nevertheless, on account of the large amount of existing facts and views, a coherent view on the relations between the structures and properties has not appeared to unify the facts. This article sketches a multi-scale point of view on the relations between the multi- scale structures and the corresponding properties.     

Examining the effect of speed,roadside features,and roadway geometry on crash experience along a rural corridor

This paper presents a current investigation into crash experience along a 15.7-mile rural corridor in southwest Montana with the aim of better understanding crash causal factors along the corridor. The study utilized ten years of crash data, geometric data, and observed freeflow speed data along the corridor. A systematic approach was used where every tenth of a mile was described in term of the crash experience, speed, alignment, and roadside features. Using bivariate and multivariate statistical anal-yses, the study investigated the crash experience along the corridor as well as some of the underlying relationships which could explain some of the crash causal factors. Results show a strong association between crash rates and horizontal curvatures even for flat curves that can be negotiated at speeds above the posted speed limit, per the highway design equations. Higher crash rates were also found to be associated with the difference between the observed free-flow speeds and the speed dictated by the curve radius or sight distance as per the design equations. Further, results strongly support the safety benefits of guardrails as evidenced by the lower crash rates and severities. The presence of fixed objects and the steepness of side slopes were also found to have an effect on crash rates and severities.     

台阶式格栅加筋挡墙现场试验研究

对广东省河龙(河源至龙川)高速公路K29+307~K29+353段路基挡墙处的分级直立式格栅加筋挡墙进行了现场试验测试分析,分别测试了挡墙从施工到正常使用期间加筋墙的加筋体内筋带拉力、土压力分布、墙面变形以及地基应力等,对测试结果进行了分析研究,探讨了相关的分布规律以及影响因素,并得出了一些新的认识和见解.