Comparison and Selection of Ventilation Schemes for Zhagaliang Extra long Highway Tunnel（扎尕梁特长公路隧道通风方案比选研究）

In order to select a suitable ventilation scheme for a single tube extra long highway tunnel with two way traffic, as well as to solve problems in smoke exhaust and personnel evacuation in such tunnel, 3 ventilation schemes are proposed. According to the characteristics of Zhagaliang extra long highway tunnel, the 3 ventilation schemes include confluent ventilation with exhaust shaft and longitudinal ventilation with jet fans, parallel pilot tunnel forced ventilation network, and longitudinal ventilation with jet fans and sectional smoke exhaust by inclined shaft. The ventilation schemes are compared from several aspects, i.e. civil construction cost, initial investment of mechanical and electrical equipment, electricity cost during tunnel operation, ventilation control, stability of ventilation network, applicability, management and maintenance. Finally, the most suitable ventilation scheme is selected by comparing the advantages and disadvantages of each scheme, i.e. longitudinal ventilation with jet fans and sectional smoke exhaust by inclined shaft. Under the normal operation condition of the tunnel, longitudinal ventilation with jet fans is adopted in the main tunnel, and on demand ventilation can be realized. Smoke can be exhausted by inclined shaft in case of fire, which can solve the problem of smoke exhaust only in two sections by the parallel pilot tunnel. The parallel pilot tunnel can also be used for personnel evacuation and rescue.     

Some Key Technical Issues on Construction of Ultra long Deep buried Water Conveyance Tunnel under Complex Geological Conditions（复杂地质条件下跨流域调水超长深埋隧洞建设需研究的关键技术问题）

For the water conveyance tunnels in the long distance water diversion projects constructed or planned in China, most of them have to pass through mountain areas with complex geological conditions, due to the constraints of route selection. These tunnels might face engineering problems such as harsh natural environment, high seismic intensity and steep terrain, leading to difficulties in construction and high operational risks. In this paper, some key technical issues on the construction of ultra long deep buried water conveyance tunnels under complex geological conditions are summarized into 5 aspects, namely, (1) exploration and testing techniques for deep buried tunnels, (2) prediction and prevention for large deformation and rock burst in the surrounding rock masses, (3) failure mechanism and anti faulting techniques of the surrounding rock masses and lining for tunnels crossing active faults, (4) synergistic load bearing mechanism and life cycle design theory for rock support system of deep buried tunnels, (5) disaster treatment for deep and long tunnels such as prevention of high pressure water inrush. The scientific and technical problems to be solved and their development directions are pointed out, which can provide some reference for engineering construction of ultra long deep buried tunnels.     

Analysis of Adaptability of TBM in Trial Boring Stage of Super long Tunnel（超特长隧洞TBM集群试掘进阶段适应性分析）

The total length of the 2nd stage water transfer project in the northern area of Xinjiang of China is 540 km. The project consists of three tunnels, namely Xi Er (XE) Tunnel, Ka Shuang (KS) Tunnel and Shuang San (SS)〖HJ6.5mm〗 Tunnel, with lengths of 139.04 km, 283.27 km and 92.15 km respectively. All of these three tunnels have deep cover and are super long tunnels, and 95.6% of the total length of these three tunnels is constructed by TBMs. KS Tunnel is the longest water tunnel built or under construction in the world. In the paper, the trial TBM boring scheme and schedule of the water transfer project are introduced; the geological conditions revealed are statistically analyzed; and main project difficulties, i.e. durability of key equipment in long distance driving, passing through fault and fracture zones, water inrush, single head ventilation and transportation in long distance tunneling, anti slope drainage, and rock breaking efficiency and boring efficiency, are put forward. The adaptability of the TBMs used is analyzed from the aspects of adaptability to different surrounding rocks, adaptability to bad geological conditions and countermeasures, long distance ventilation and belt conveyor mucking and countermeasures, and TBM boring stability (such as equipment availability, boring time proportion, system malfunction and operation time). The following conclusions are obtained: (1) Accurate geological survey is the precondition of efficient tunneling. (2) The open type TBM can better adapt to Grade Ⅱ and Ⅲ of surrounding rocks, jointed and fractured zones and small faults; the adaptability of the TBMs used to the large scale fault fracture zones and water rich strata in this project is poor, and it needs to be improved in aspects of TBM equipment, supporting and construction technology. (3) The average availability of the TBM equipment in the trial boring stage is 89.9%, however, the malfunction rate of some ancillary equipment is high, particularly oil leakages occur to the main bearing seals; in order to achieve long distance tunneling, it is necessary to further improve the reliability and durability of the TBM equipment. (4) The average net boring efficiency in the trial boring stage is 296%, and TBM1 in Section Ⅱ of SS Tunnel achieves up to 45.2 % net boring efficiency; and highest monthly progress rate is 1 280 m, which created the highest record of the open type TBM boring in China. (5) TBM need to make great efforts to achieve 90% of the equipment system′s availability and over 40% of the tunneling efficiency.