超高地热条件下特长引水隧洞钻爆开挖关键技术

在娘拥水电站引水隧洞爆破后岩体表面温度高达75℃,炮孔涌水温度高达86℃的工况下,分析了超高地热对钻爆开挖施工的影响,研究建立了超高地热条件下炮孔冷却循环系统,有效地将炮孔温度降至35℃以下,为超高地热段隧洞的正常建设创造了有利条件。     

就地热再生技术在G319路面养护工程中的应用

为保证就地热再生技术在G319路面养护工程中的应用质量,通过对G319路面养护工程进行详细的现场勘查和室内试验,分析路面结构的完整性和承载能力,完成施工全程施工温度等监控和室内试验,对就地热再生技术方案的确定提供了数据支持。结果表明:就地热再生施工过程关键温度波动幅度较为明显,关键工序的超高温度对混合料的抗水损害能力有不利影响,需要建立温度监控机制,并提出就地热再生施工各工序的建议控制温度,为就地热再生技术施工提供参考。     

闲林水库工程大毛坞施工支洞及正洞通风技术

结合杭州市闲林水库输水隧洞工程实况,提出了大毛坞施工支洞及正洞的通风方案,通过计算洞内工作面所需风量与阻力,确定了洞内通风量,并阐述了通风系统的施工管理措施,改善了隧道的通风环境。     

高地温隧洞温度场数值模拟研究

以新疆某水电站高地温引水发电隧洞为依托,对高地温段引水发电隧洞在有无EPS保温隔热层下的温度场分布进行模拟研究。结果表明,距离隧洞中心越远,在有、无EPS保温隔热层条件下隧洞的温度均越高;EPS保温隔热材料厚度依次取3、5、10cm时,隧洞衬砌支护结构温度梯度明显降低,且在EPS保温隔热层处温度发生突变,突变处温度幅值依次为20.6174、26.7323、39.3442℃;EPS保温隔热层越厚,衬砌支护结构温度梯度越小,与现场实测结果极为吻合。鉴于此,在高地温引水隧洞施工过程中,可在二次衬砌前施做保温隔热层,用于阻断来自围岩深处的高温,从而降低衬砌支护结构与洞内环境温度的温差,减小二次衬砌结构所受到的温度应力,为高地温引水隧洞降温措施的设计与施工提供理论依据。     

高海拔特长公路隧道洞内环境现场试验研究

为应对高海拔、低气温、低含氧量及低气压环境下白茫雪山3号隧道施工难题,开展隧道洞内湿度、温度、氧气及一氧化碳浓度环境现场试验研究。结果表明,洞内湿度能稳定在80%左右,洞内温度多在10℃以上,满足混凝土强度增长要求,但需加强冬季洞内环境温度场监测;隧道掘进400m以后,O2浓度成线性降低,CO浓度急剧增大,均不满足规范规定值,需加大通风量。其结论可为高海拔特长隧道设计施工提供一定参考和借鉴。     

山西引黄隧洞涌水封堵灌浆施工技术

山西省中部引黄工程某隧洞支洞及主洞开挖过程中,渗水、涌水严重,采用抽排方法无法正常开挖施工,需采用灌浆方式进行堵漏。本文以山西引黄隧洞的灌浆堵漏为例,分析了隧洞渗水、涌水的原因,阐述了灌浆施工的设计要点,施工方法、施工要点。采用灌浆堵漏后隧洞内渗水大量减少,灌浆效果良好,为隧洞开挖施工创造了有利的施工条件。     

侧卸装载机在隧洞施工中的使用要点

在现代水利枢纽工程、高速公路、铁路、泄洪工程施工中,经常有隧洞施工项目,根据隧洞尺寸的大小以及施工环境的不同,我们采用的出料装载机械也有所不同。在一些尺寸较大的涵洞施工中,我们常常用侧卸装载机作为装载设备。但隧洞施工有别于露天施工,根据我们在施工中积累的经验,侧卸装载机在使用过程中应注意以下几个方面的问题。1有效的安全防护措施在隧洞施工过程中,洞内的塌方、岩爆、洞顶落石等是经常发生的。如果没有有效的防护措施,势必会造成对设备或人员的伤害。侧卸装载机在洞内出渣过程中遇到危险的可能性较大,因此要特别注意安全防…     

冷龙岭隧洞施工创五项全国第一

铁十八局一处三公司“引硫济金”项目部在担负冷龙岭隧洞施工中,先后攻克了施工中的道道难关,取得了5项国内隧洞施工第一。一是采用常规国产设备钻爆法施工,创造了高原严寒地区小断面长隧洞钻爆法最高月掘进191ｍ、平均月掘进118ｍ、最高月衬砌300ｍ、最高月成洞180ｍ的好成绩;二是采用长吸短压混合式管道通风方案,在国内首次实现了海拔3420ｍ以上高原小断面隧洞独头通风6000ｍ,洞内作业环境达标;三是首创了风压供水技术,成功地解决了严寒地区及外界环境不允许设置高水位的隧洞施工给水技术难题;四是创造性地将膜富氧技术应用于高原隧洞创建…     

测量技术在八十一大坂超长隧洞中的应用

通过测量技术在八十一大坂超长隧洞中的应用,对隧洞施工测量中洞口控制网布设、数据处理及其误差对贯通的影响、洞内基本控制网的布设、平差及检核方法等进行了研究,从而为今后TBM施工测量工作奠定基础。     

双护盾全断面掘进机洞内拆卸重难点分析

结合新疆大坂隧洞工程施工实例,对采用全断面双护盾掘进机（简称TBM）施工的隧洞如何在洞内拆卸的难点与重点送行了分析,并提出了相应的措施,对其他采用TBM施工的工程提供了指导。     

鄂尔多斯盆地地热系统

本文是在前人研究基础上,结合鄂尔多斯盆地地下水勘查获取的地温资料,阐述了鄂尔多斯盆地地热形成的地质条件,大地热流的分布特征。描述了不同埋深的地温场的特征和地热梯度的空间变化规律,圈定了地下热水的分布区,利用最新的地下水资源评价的结果,概略计算了盆地的地热资源。     

高地温隧道地温特征及预测研究

尼格隧道属长大深埋隧道,兼有高水温与高岩温,最高水温达63.4 ℃,最高岩温达88.8 ℃,最高气温达56.4 ℃。为了研究隧道地温特征并进行地温预测,针对性地设计了一系列地温测量方案,研究成果表明:灰岩段表现为高水温,水温＞气温＞岩温,水温与气温随着隧道进深及埋深呈现上升趋势,出水量及水温在接触带附近达到高值,洞内气温受水温、隧道出水量、积水量影响大;花岗岩段表现为高岩温,无水,岩温与气温随隧道进深及埋深呈现上升趋势,两者差值约为25~30 ℃;超前钻孔在孔深＞2 m时岩温达到稳定;一个完整施工循环的施工环境气温呈现4个阶段:气温下降阶段(打钻施工环节),气温骤升阶段(爆破施工环节),气温快速上升阶段(新爆围岩散热),气温缓降阶段(出渣施工环节),出渣环节由于车辆及挖机等机械作业影响,气温出现多处异常高值;施作二衬后,二衬内外壁温差约3.4 ℃;利用热量传递理论、地热成因理论预测的最高地温值与实测值较为吻合。该工程案例颇为典型,本文研究对西南高地热区隧道工程建设具有指导意义。     

Potential hazards to a tunnel caused by adjacent reservoir impoundment

A reservoir impoundment located near a tunnel structure negatively affects groundwater seepage to varying degrees. This can result in water inflow, structural collapse, and other engineering hazards during tunnel excavation. In addition, in cold regions, reservoir impoundment and water seepage can exacerbate frost heave damage during tunnel operations. This paper describes a comprehensive case study on the quantitative evaluation of the seepage effects of the proposed Longsheng Reservoir on the adjacent proposed Kouzi village tunnel (located in Ulanchap, Inner Mongolia, North China). An engineering geology survey was conducted to identify the topography and geological features in the tunnel and reservoir area. A geohydrological survey was conducted to identify groundwater runoff patterns and to assess the possible seepage paths. Pumping and injection tests were conducted to characterize the in-situ permeability of the strata. Based on the detailed field information, the seepage field and stress field of the study area were investigated using COMSOL Multiphysics and ABAQUS software. From these numerical simulations, the evolution of the water inflow and the stress/strain field in the shallow buried section of the tunnel could be predicted quantitatively at different construction and operation stages. This study showed that the seepage influence of the Longsheng Reservoir on the Kouzi village tunnel during the excavation and operational stages will be relatively weak. However, structural collapse of the tunnel and water inflow are likely to occur beneath the two gullies. Mitigation measures such as impervious walls and inverted arch structural elements were proposed to address these potential hazards.

     

Experimental study of the effectiveness of a water system in blocking fire-induced smoke and heat in reduced-scale tunnel tests

A water system, consisting of several water mist nozzles, has been installed in a reduced-scale tunnel. Its effectiveness in blocking fire-induced smoke and heat is tested, with and without longitudinal ventilation. A total of 14 fire tests have been carried out, with 250 ml methanol in an iron tray (25 cm × 20 cm) as fuel. Temperatures have been measured by 30 thermocouples, located upstream and downstream of the fire location. The aim is to assess the effectiveness of the water system in preventing smoke spread and in reducing the temperature in the tunnel. Interaction of the water with the fire is avoided. The impact of water pressure, ventilation velocity and nozzle arrangement on the effectiveness in smoke blocking and temperature reduction is discussed. The result confirms that the water system effectively reduces the temperatures and prevents smoke spreading in the absence of longitudinal ventilation. However, strong longitudinal ventilation (0.8 m/s ventilation velocity in the reduced-scale tunnel, corresponding to critical velocity in full-scale (1:10) tunnel) reduces the effectiveness in blocking the smoke spreading by the water system, although the temperature reduction downstream the water system remains in place. Higher water pressure makes the cooling effect stronger, because more and smaller water droplets are injected into the tunnel. For a given level of water pressure level, the impact of the nozzle row configuration is small in the tests.     

Effects of Ventilation and Water Spray in a Model-Scale Tunnel Fire

At the present time, eight new long tunnels are currently being constructed in Taiwan and plan to utilize sidewall sprinkler nozzles to conduct fire protection. To explore the effect of ventilation and water spray on tunnel fires, this research used a 1/5.5 model scale tunnel to perform experiments, while using a heptane oil pan of 0.45 m diameter as the fire source. Under five different ventilation velocities, the cooling effects of water spray on tunnel fires was discussed while controlling the water density at 2.3 mm/min. The critical velocity without water spray was 1.24 m/s, which fits empirical equations by past research. Under a ventilation velocity of 0.87 m/s, the smoke backlayering would be 2 m without water spray, while none was present with water spray. Overall quantitative analysis shows the significance of water spray in affecting backlayering, and it can be acknowledged that water spray can prevent backlayering from larger fires under the same velocity. This research used visual and temperature measurement methods to determine the location of backlayering, and it is recommended that maximum temperature gradient be used in future research as the basis for smoke backlayering location.     

火灾对原型盾构管片接头防水性能损伤试验研究

通过盾构隧道衬砌管片原型火灾试验和接头防水橡胶条高温耐水压试验,研究了火灾高 温条件下管片接头温度传导以及温度场分布规律;火灾高温条件下管片接头变形规律;火灾高 温条件下盾构管片接头防水性能变化规律。从接头温度分布、变形特性以及防水性能等方面对 盾构隧道管片接头在火灾条件下的损伤研究中得到：（1）火灾发生30min左右是管片受火面混 凝土崩裂和径向裂缝集中发展时期,高温引起管片接头变形较大,火灾持续时间直接影响管片 接头防水性能变化;（2）火灾中,接头处三元乙丙橡胶比遇水膨胀橡胶耐高温性能要好;（3 ）火灾发生时,165℃是管片衬砌接头密封橡胶条是否具有防水性能的临界温度。     

Design of grouting with silica sol in hard rock – New design criteria tested in the field, Part II

An extensive field test was conducted in spring 2005 in the Törnskog Tunnel and consisted of design, execution and evaluation of a grouting campaign for 100 m of tunnel. The field test was part of the normal construction of the tunnel. This paper describes how the design of the grouting was coupled with the actual grouting procedure. A preliminary investigation of the tunnel showed that the location where this field test was conducted had a large fracture zone. A drill-core was taken in this zone and hydraulic tests were performed. From the evaluation of the rock core a fracture aperture distribution was assessed and the grouting design was focused on this part of the tunnel. The evaluation showed that apertures down to 14 μm needed to be sealed to cope with stipulations set for leakage into the tunnel (2 l/min and 100 m of tunnel). A design was made based on silica sol, where a critical penetration length was decided and the layout of the grouting fan could be determined. A new design was chosen, with a specific pumping time of 30 min at a grouting pressure of 1.1 MPa. The design worked well and the water ingress was reduced. A drip characterisation in both tunnel tubes was made. One tube was grouted with silica sol and the other with cement following a more traditional approach. The drips were both larger and more frequent in the cement-grouted tube than in the silica sol-grouted tunnel. Eight out of nine fans grouted with silica sol showed a significant sealing effect. For one fan the design was not followed. Instead, the workers used the more traditional method, i.e. only pumping until the design pressure was reached, which produced a poor result. This paper demonstrates the efficiency of design methodology that takes into account the hydraulic apertures and that the required minimum penetration length can be coupled to the apertures when formulating the grouting criteria.     

Geotechnical considerations in an unlined high pressure tunnel at Lower Kihansi in Tanzania

The Lower Kihansi unlined high-pressure tunnel is the first of its kind to be constructed in Tanzania. The pressure tunnel consists of a 500 m vertical shaft and a 2.195 km inclined headrace tunnel. The cross sectional area of the shaft is 25 m² and that of the headrace tunnel is 30–37.5 m². The headrace tunnel slopes 1:7 towards the powerhouse cavern. The pressure tunnel acts as waterway towards the underground hydroelectric power generation plants with a maximum generating capacity of 180 MW. The Kihansi River has been deviated through the shaft and headrace tunnel from an elevation of 1,146–300 m above sea level. The maximum water pressure created by this deviation is 8.5 MPa.The decision not to steel line the pressure tunnel was reached after the excavation and documentation of the underground rock mass. The hydraulic jacking and hydro-fracturing tests confirmed the rock to have a minimum acceptable confining stress of 9.6 MPa, capable of withstanding the expected water pressure in the tunnel. The permeability of the rock mass is relatively low and any poor zones were sealed by grouting.The discontinuities had a favourable orientation with respect to the tunnel axis such that rock bolts and steel fibre reinforced shotcrete could be used to provide the necessary support. No failures occurred and the decision not to line the Kihansi high-pressure tunnel has proved both technically acceptable and economical.     

高水压富水区隧道限排衬砌注浆圈合理参数研究

海底隧道深埋于海水以下,处于高水压富水区,隧道结构设计时需要考虑外水压力,如果采用"堵水限排"的防排水设计原则,能够以较小的排水量显著降低作用在衬砌上的外水压力,从而使隧道结构设计更加经济。注浆圈合理参数的确定是"堵水限排"的核心问题。基于穿越高水压富水岩溶区的圆梁山隧道工程,通过理论计算和分析,得到了注浆圈参数变化对隧道涌水量和衬砌外水压力的影响规律;提出了隧道排水率的概念,分析了隧道排水率与衬砌外水压力之间的关系。在此基础上提出了确定注浆圈合理参数的方法和程序,给出了圆梁山隧道注浆圈的合理参数值,并在现场得以应用,取得了理想的效果,注浆后实测隧道涌水量与理论计算值基本一致。研究结果表明:衬砌外水压力折减系数取决于隧道排水率,只有当隧道排水系统能够将渗透到衬砌背后的地下水全部排出时,衬砌外水压力才能完全消除;注浆圈的作用不是分担衬砌外水压力,而是通过封堵地下水降低隧道涌水量,从而以较小的排水量可显著降低甚至消除衬砌的外水压力。研究成果对类似高水压富水区以及海底隧道防排水设计具有一定的参考价值和借鉴作用。