In this study, dynamic pressure response of base structure of Fu Yingzi tunnel along Zhangjiakou to Tangshan was simulated through field large-scale excitation test under the class V rock conditions when the heavy haul trains with axle weights of 250 kN, 270 kN, and 300 kN passed. Dynamic pressure attenuation values at measuring points were presented when axle weight was reduced. According to the earth pressure time history chart of field measurement, horizontal and vertical distributions of dynamic pressure of the measuring points in each structural plane were analyzed. The results indicate that dynamic pressure of each measuring point in heavy haul line of double line tunnel is greater than passenger train line, and the dynamic pressure of the corresponding measuring points below the railway track under different axle load of heavy haul trains is greater than other measuring points. Stress concentration is found to appear in the structure and surrounding rock at corresponding heave haul position, which is more likely to cause the structure to crack or hole generation in wall rock under the condition of broken rock compared with the test results on the surface of class IV grade surrounding rock. Train load attenuates drastically due to cushioning of the bed structure and inverted arch filling as it vertically transfers, but there is only small attenuation in inverted arch. Current designed basement structure thickness cannot meet the demand of lifting axle load.

For studying the effect of enomously great train load acting on the basement structure of heavy haul railway tunnel,a large-scale site vibration test was carried out on the Fuyingzi tunnel with a dynamic and long-term loading of 27t axle load of heavy haul train.Comparing with the remote measured dynamic data,the objectivity and accuracy of the test was verfied.The dynamic contact pressure responses and long-term changes of a double line heavy haul railway tunnel basement structure,including the ballast,invert filling,inverted arch structure and rock contact surface,were instigated in the environment of heavy axle load and high density transportation.The results show that the vibration excitation test can well test the dynamic characteristics of the basement structure under 27 t axle load.The dynamic responses and long-term effects on each component structure are most obvious at the position just under the heavy load track and gradually weakened from top to bottom along the vertical depth.The long-term effect and dynamic pressure at each positon are influenced by the dynamic load of train.The greater the dynamic response,the more obvious the longterm effect.The experimental results provide a theoretical basis for the stability evaluation and parameters design of the base structure of double track heavy-haul railway tunnels.

The oxygen supply and ventilation of high altitude tunnel in low pressure and low oxygen environment are very important.The field test and monitoring methods are adopted;the hypoxia situation of construction personnel, oxygen supply effect and mechanical pollution of high altitude tunnel are studied;and theoretical reduction and numerical calculation are carried out.Some conclusions are as follows: 1) The hypoxia of construction personnel can be divided into 4 grades, i.e.serious hypoxia (Grade Ⅰ), ordinary hypoxia (Grade Ⅱ), potential hypoxia (Grade Ⅲ) and non hypoxia (Grade Ⅳ).2) The CO volume fraction models in different altitudes are obtained.3) The calculation formula for air duct leakage rate based on altitude correction coefficient are deduced by air flow theory at air duct opening.4) The altitude correction coefficient formula for air pressure and power of fan is obtained.5) The labor intensity index and grade in different altitudes considering average energy metabolism rate based altitude correction coefficient are obtained.

During tunnel construction at high altitudes, construction crews often encounter an oxygen deficit and their labor intensity is different than when they are working in normal-altitude (plain area) tunnels. In this paper, us-ing the Queershan tunnel as an engineering case, the labor intensity classification standard for tunnel construction procedures in a plain area is obtained according to the national physical labor intensity classification standards and actual research results. Based on the principle of alveolar ventilation, the correction coefficient of the average meta-bolic rate changing with altitude is obtained. Considering the correction coefficient of the average energy metabolic rate changing with altitude for physical labor, the labor intensity indexes and classifications of critical tunnel con-struction procedures under different altitudes and the labor intensity classification of critical construction proce-dures in the Queershan tunnel are calculated. By comparative analysis, it is found that the labor intensity classifica-tion of critical construction procedures in the Queershan tunnel is generally one level higher than the labor intensity of tunnel construction in plain areas (normal altitudes).

With the increase of single tunnel length, traditional tunnel construction method can't meet the requirements of the construction environment. In this paper, the control values of temperature, humidity and wind speed are gained by statistics and analysis. Based on the field test of the TBM tunnel construction environment, this paper puts forward the problems existing in the construction of the tunnel, and puts forward the corresponding improvement suggestions.

The variation process of temperature field in rock and support structure is a significant and fundamen-tal issue in the area of study for high rock temperature tunnel.The temperature change laws of surrounding rock,primary support and secondary lining during the construction of high rock temperature railway tunnels were studied by the three-dimensional thermal analysis and in-situ test.The results showed that the influence scope of tunnel excavation on rock temperature field was in positive correlation with the initial rock tempera-ture.The quadratic functional relation existed between the temperature influence scope of rock above the vault, beside the wall or under the inverted arch and the initial rock temperature.The temperature decreasing modes of rock around the tunnel can be divided into sudden change and gradual change types.The former refers to the sharp drop of the rock temperature in the first 0~5 d and gradual decrease in the next 5~60 d.The latter refers to even and gradual decrease of the rock temperature in 0~60 d.The temperature decreasing range of rock a-round the tunnel was related to the initial temperature and position of the rock.The temperature decreasing mode of primary support and secondary lining was characterized by sudden change.Their temperatures fell sharply in the first 5~7 d until they remained constant and were equal to the air temperature in the tunnel.

在隧道施工过程中,层状围岩是极为常见的一类岩体。这类岩体的工程稳定性一般较差,容易造成安全事故,其中尤以水平层状围岩的稳定性最差。水平层状围岩隧道拱顶岩层常常分层剥落,不仅易形成平拱,使超欠挖严重及成型很困难,而且拱顶掉块也会严重威胁现场施工人员安全。针对这一问题,利用离散元方法研究了水平层状围岩的变形和破坏特征,获得了一些有益的成果,同时根据现场实际情况,提出了一些操作性较强的应对措施,可作为水平层状围岩设计和施工的参考依据。

In the tunnel construction process, the displacement monitoring data are usually used as the most important basis for identifying the stability of the surrounding rock, and sometimes even the only one. However, in the tunnel design process, no displacement criterion is established for identifying the stability of the surrounding rock, for the large differences among surrounding rocks with different lithology and geological environments. Furthermore, shape, span and burial depth of the tunnel would probably also effect the displacement of the surrounding rock. On the other hand, statistical analysis of the on-site displacement data indicate that under general conditions of surrounding rock, the relative displacement value of the same grade rock has obvious cohesion compared with obvious differences between the relative displacements values of the different grades. With this characteristic, an identifying rule of stability can be setup for all grades of surrounding rocks with statistical analysis of the on-site displacement data; and then the rule can be used for classification of surrounding rocks. With the wide application of mining method based on the main thought of the new Austrian tunneling method(NATM) and controlling displacement of surrounding rocks in the construction of high-speed railway and expressway tunnels; the above identifying rule of stability and classification method of surrounding rocks will more in line with current technological level of tunnel construction.

The classification methods of special surrounding rocks of tunnels in loess,swelling soil and fault and fracture zones in China and abroad are summarized.Parameters that can reflect the characteristics of the special surrounding rocks of tunnels are obtained.The study shows that loess can by classified by considering the geologic age,natural water content and dry density,swelling soils can by classified by considering the plastic index,free swelling rate and normal water content and fault and fracture zones can be classified by considering the geological and mechanical characteristics.