深埋富水大型溶腔隧道施工技术——宜万铁路野三关隧道“602溶腔”释能降压及安全施工技术

文章以宜万线野三关隧道"602"溶腔为例,对深埋大型富水溶腔隧道的综合施工技术进行了系统的论述,主要包括查找溶腔、判释溶腔、锁定溶腔、打开溶腔、处治溶腔等释能降压技术,以及泄水洞、信息化注浆、开挖支护、长期监测、结构安全评价等过溶腔安全施工关键技术。     

山区隧道突泥处治施工技术

文章以某山区公路隧道施工为背景,针对隧道在开挖过程中出现的塌方、涌泥等现象,采用C6超前钻探技术全面探测前方溶洞溶腔规模、大小、形状以及围岩情况,在初支变形段增设护拱,采用大管棚及小导管对溶腔段进行注浆加固处理,并施作止浆墙,后续对溶腔泵送C25混凝土进行加固,在规定时间内安全有效地处治了突泥病害,无安全事故发生,效果显著,确保隧道顺利实现贯通。     

宜万铁路野三关隧道602溶腔处治

文章主要介绍宜万铁路野三关隧道DK124+602高压富水溶腔的规模与处治技术.602溶腔影响隧道纵向达20 m,向上与3号暗河连通,最大涌水量48万m3/d,实测水压1.0 MPa.该溶腔段施工采取了高位排水降压、帷幕注浆、管棚预支护等技术措施,实现了降压、加固、堵水、肪渗的目的,防止高压渗水直接传递给隧道结构,为隧道开挖通过溶腔及运营结构安全提供了重要保障.     

砂浆回填帷幕注浆在高压富水溶腔处治中的应用

宜万铁路云雾山隧道DK245+260高压富水溶腔,纵向长约13.28m,宽约31.2 m,腔体内充填粘沙土,施工中观测到最大水压为0.56 MPa,最大出水量为1 100 m3/h,腔体内存在大型空腔,施工中多次突泥突水.现场先采用M10砂浆回填溶腔空腔,后采用全断面帷幕注浆构筑截水帷幕,成功完成该溶腔的处理,减少了工程损失,保证了隧道的施工安全.     

公路隧道坍塌治理方案探讨

文章根据福州地区某隧道洞口浅埋段坍塌冒顶处理工程实例,在分析塌方原因的基础上,探讨了隧道洞l::it浅埋段坍塌防治措施,对同类隧道的施工具有一定的参考价值.     

富水岩溶区基坑稳定性影响规律与分析

广州、深圳等城市分布有富水岩溶区，地下水丰富、发育形态复杂，在地铁建设过程中易导致突涌水、坍塌等安全事故。依托广州某地铁车站工程，首先通过现场抽水试验得到场地渗透系数为6.32 m/d，预测了基坑总涌水量，采用数值模拟进行了两次过程试验，得到降水终态误差分别为14.92%和7.08%，结果较为理想。进一步研究了不同形态的富水溶洞对基坑稳定性的影响规律，并基于灰色关联理论对各影响因素进行敏感性分析，其中地下水位和溶腔水压对围护结构水平变形的影响较大，敏感度分别为0.946和0.925；洞距和溶腔水压对地表沉降影响较大，敏感度分别为0.999和0.975；洞距和直径对支护结构最大拉应力和基底孔隙水压影响较大。     

马鹿箐隧道高压富水大体量充填性溶腔处治技术

宜万铁路马鹿箐隧道DK255+978处通过一高压富水隐伏溶腔,先后发生多达19次的突涌水(泥)灾害.在对该高压富水隐伏岩溶的处治中,系统地运用了释能降压原理,释放了溶腔所存储的能量,降低了水土压力对隧道的稳定性影响.释能降压技术主要采取了综合地质预报手段探明溶腔边界、内部充填物特性和分布特征等,并根据溶腔的水压、水量测试结果进行排水系统规划、钻孔泄水,采用控爆措施揭开溶腔,并进行实时预警预报监控.结果表明,运用释能降压技术处治马鹿箐+978溶腔,规避了岩溶溃水的风险,取得了良好的效果.     

明月山特长隧道涌水突泥综合处理措施

明月山隧道为具有多种不良地质的特长公路隧道,施工中发生了特大涌水、突泥灾害,造成严重坍塌事故。通过对隧道涌、突水灾害产生的原因及坍塌形态进行详细的分析研究,采取了一系列行之有效的处理措施,并对地表、洞身及坍塌体进行了固结和加固,快速而有效地完成了突泥及坍方段施工。文章介绍了隧道涌水、突泥灾害的概况和采取的综合处理措施。     

宜万铁路马鹿箐隧道+978溶腔预测预报

马鹿箐隧道先后发生了"1.21"、"4.11"等多次突涌水事故,为探用Ⅱ DK255+978 溶腔岩溶水规模,前期采用出口平导探测,后期进行了补勘与强化预测、预报.施工中通过运用 TSP203、红外探测、地质雷达、超前地质钻孔等多种探测技术,准确锁定了溶腔含水体区域和溶腔边界,准确掌握了溶腔充填物性质,成功地保障了其后...     

碳质板岩隧道塌方处理方案探讨

文章结合十堰—天水高速公路磨河村隧道塌方案例,分析了隧道塌方原因,并从经济性、安全性、可操作性等方面综合比较了三个处理方案。最终选择的处理方案为:利用弃碴回填下台阶;加固上台阶开挖台车,以作为防护棚架;对坍塌前后段及坍塌口进行加固处理,施做喷混凝土支护及二次衬砌;利用混凝土及干砂对塌腔进行回填处理。该处理方案安全、合理、经济、快速、可行,且效果良好。     

钉形桩在市政道路工程中的应用

水泥土深层搅拌桩是用于加固饱和软粘土地基的一种较新的地基处理方法,具有施工简便、工期短、振动小等优点,在软土地基处理工程中得到广泛应用。文章介绍了钉形水泥土双向搅拌桩的优点与施工流程,并对其在武汉四新地区软土地基处理中的应用进行了试验研究。     

Analytical model of traffic delays under bus signal preemption: Theory and application

Major emphasis has been placed in recent years on the improvement of the operations of existing transportation facilities, using Transportation Systems Management strategies. Accordingly, preferential treatment of high occupancy vehicles is playing an increasing role in transportation projects. This paper deals with one of these strategies, the priority treatment of buses at signalized intersections. Such treatment is aimed at improving the capacity of intersections. The paper develops an analytical model of delays at signalized intersections under a bus preemption scheme. The analysis is presented for the simplest case, i.e., two intersecting one-way streets. The results suggests that the benefits of bus preemption can be increased by properly adjusting several design parameters such as cycle and phase duration of the preempted phases as well as the non-preempted parameters. The model outlined in this paper is applicable to any situation in which stochastic variation is introduced into the signal cycle as well as to bus preemption. Consequently, other potential applications of the model include the design/analysis of traffic actuated signals, and pedestrian actuated signals.     

高速公路服务区污水处理信息监控系统方案探究

小型污水处理设施是高速公路服务区配套的污水处理环保设施,由于高速公路服务区远离城市,污水处理设施点多、线长、面广,如沿用传统人力运管方法,受制于管理单位层级多、责任主体多,监管流程复杂且缺乏专业人员等因素,难以保障污水处理设施安全稳定运行。本文针对该问题,分析传统人力监管存在的问题,从系统构成、主要功能方面提出一种服务区污水处理信息监控系统方案。     

The tax treatment of company cars, commuting and optimal congestion taxes

In Europe, the preferential tax treatment of company cars implies that many employees receive a company car as part of their compensation package. In this paper, we consider a model in which wages and the decision whether or not to provide a company car are the result of direct negotiation between employer and employee. Using this framework, we theoretically and numerically study first- and second-best optimal tax policies on labour and transport markets, focusing on the role of the tax treatment of company cars. We obtain the following results. First, higher labour taxes and a more favourable tax treatment of company cars raise the fraction employees that receives a company car; congestion and congestion tolls reduce it. Second, in countries that provide large implicit subsidies to company cars, eliminating the preferential tax treatment of company cars may be an imperfect but quite effective substitute for currently unavailable congestion tolls. The numerical illustration, calibrated using Belgian data, suggests that it yields about half the welfare gain attainable through optimal congestion taxes. Third, the favourable tax treatment of company cars justifies large public transport subsidies; the numerical results are consistent with zero public transport fares. Finally, we find that earlier models that ignored the preferential tax treatment of company cars may have substantially underestimated optimal congestion tolls in Europe. The numerical illustration suggests that about one third of the optimal congestion toll we obtain can be attributed to the current tax treatment of company cars.     

预应力混凝土管桩在上海白龙港污水处理厂升级改造工程中的应用

预应力混凝土管桩是被普遍用于高层建筑地基基础的一种桩基施工工艺，用于市政污水处理工程尚不多见。结合工程实际，对解决工程基坑抗浮和沉降的方法作了比选，并简要阐述了预应力混凝土管桩压桩及其质量控制过程。     

Truck versus pipeline transportation cost analysis of wastewater sludge

Domestic and industrial sludge generated at wastewater treatment facilities is considered a potential biomass source for producing biodiesel. However, transportation of large amounts of sludge from wastewater treatment facilities to a biorefinery is expensive. The objective of this paper is to identify the proper transportation mode to use as a function of the volume shipped and transportation distances. Currently, sludge is mainly shipped by truck and pipeline. We estimated that the fixed and variable cost components of pipeline transportation for a volume such as 480 m³/day and a distance of 100 miles are $0.116/m³ and $0.089/m³/mile, respectively. We estimated the biomass (sludge) transportation cost per gallon of biodiesel, and observed the changes in these costs as a function of distance traveled and volume shipped. The outcomes of this study have the potential to help biofuel plants make better biomass transportation decisions, and consequently reduce the price of biodiesel significantly.     

Predicting asphalt pavement crack initiation following rehabilitation treatments

Prolongation of the service life of pavements requires efficient prediction of the performance of their structural condition and particularly the occurrence and propagation of cracking of the asphalt layer. Although pavement performance prediction has been extensively investigated in the past, models for predicting the cracking probability and for quantifying impacts of associated explanatory factors following pavement treatment, have not been adequately investigated in the past. In this paper the probability of alligator crack initiation following pavement treatments is modeled with the use of genetically optimized Neural Networks, The proposed methodological approach represents the actual (observed) relationships between of probability of crack initiation and the various design, traffic and weather factors as well as the different rehabilitation strategies. Data from the Long Term Pavement Performance (LTPP) Data Base and the Specific Pavement Study 5 (SPS-5) are used for model development. Results indicate that the proposed approach results in accurately predicting the probability of crack initiation following treatment; furthermore it provided information on the relationship between external factors and cracking probability that can help pavement managers in developing appropriate rehabilitation strategies.     

湖南桂武高速公路某路堑边坡稳定性分析

文章以湖南省桂武高速公路K160+800~K160+941右侧路堑边坡为例,分析了上覆土层为高液限红粘土、下覆地层为软弱碳质灰岩路堑边坡失稳的形式与成因,介绍了边坡稳定性计算方法,并提出了该类型边坡失稳的处置方案。稳定性计算表明,在常规下稳定的边坡,在降雨作用下则不稳定,处置该类型边坡应同时做好支护和排水工作。     

化学灌浆处理水泥砼路面板底脱空方法

文章针对广西柳州-王灵高速公路水泥砼路面板底存在脱空问题,分析了病害产生的原因,介绍了应用化学灌浆处理时从灌浆材料、设备的选定,到施工工序,质量检查,处理效果及方法的过程,提出了处理工程中还存在的问题及对策,对处理水泥砼路面板底脱空及改善路面的使用性有一定的参考意义。     

A Methodology for estimating traffic safety improvements at intersections

Intersection accidents represent a significant proportion of overall motor vehicle accidents. More accurate estimates of the actual effectiveness of intersection safety improvements are required. This study develops an improved methodology for post-implementation evaluation of safety countermeasures at intersections. Accidents are random, rarely occurring events. For a given time period, this leads to random fluctuations in accident frequencies, which suggests that statistical analysis employing confidence intervals, rather than point estimates, is required. Two technical problems complicate this treatment of accident occurrence as a random variable. The first problem is that identifying of hazardous locations is generally based on above-average accident frequency during the most recent period(s) for which data is available. The second problem arises from changes in external factors such as traffic volume, motor vehicle safety standards, etc., during the period of analysis, which may also affect traffic safety. A “combined” approach which addresses these technical issues is developed. Empirical Bayesian methodology is combined with regression techniques to derive a more accurate measure of the effect of safety treatments. An important consideration is the derivation of the variance of this measure, so that appropriate confidence intervals may be constructed. The approach is then applied to a sample of locations that underwent treatment by the Massachusetts Department of Public Works (MDPW). We compare our results to those which might be obtained using alternative methodologies that correct for neither or only one of the technical problems. We also illustrate how preliminary conclusions may be drawn regarding the effectiveness of broad categories of treatments, and how individual sites requiring further investigation may be identified.