Experiment Research Of Construction Technique And Technology Of The Plateau Tunnels In Permafrost Soil

The Kunlun-Tunnel and the Fenghuo-Mountain-tunnel in the Gela-section of Qinghai-Tibet railway lie in the permafrost area of Qinghai-Tibet plateau, at an elevation of more than 4500m. These are the only two tunnels constructed in the 550km long permafrost area of Qinghai-Tibet plateau, and they are the only highest tunnels built under such condition in the world. This area has the particular dry-cold climate. Because building tunnel under this condition is first in the history of the world tunnel construction, which we meet are all the new technique subject. This paper mainly discusses the tunnel construction technique in permafrost Soil on the plateau.1. With the use of differential equation, the paper studies the temperature field of the tunnel country-rock in permafrost soil, deals with practice temperature data, finds out and catches hold of the variable regularity of the temperature field. These provide theory supply of tunnel construction measure to reduce the construction effect to the permafrost soil around tunnel. This research is first developed in our country, and it fills up the blank of our country.2. Building physical model of the temperature field in the tunnel or in the ventilating hole to calculate, analyses and study the regularity of the temperature field inside the tunnel and the ventilating hole in simulation. And it also finds out the relation of the air temperature in the ventilating hole. These provide theory supply of choosing tunnel ventilating mode and measure. This research result has directive significance to the similar project. Meanwhile, shoulder oxygen-supply in Kunlun-Tunnel and pervading-in-the-tunnel oxygen-supply in Fenghuo-Mountain-tunnel are all domestic initiation.3. With a lot of tests, such as mix ratio test, the amount mixed with mineral admixture test, the proper temperature of shotcrete technology system test, the shotcrete technology process and engineering factor test, concrete strength and antifreeze-thaw tests, and tests of bond strength between shotcrete and rock, it proves that through adopting special construction craft, wet-shotcrete can be a mean of tunnel protecting in permafrost soil of plateau, and also unifies the understanding of the circle of domestic tunnel on this question. At the same time, it establishes thetunnel construction technics in permafrost soil on plateau, accumulating the experience of adopting wet-shotcrete in permafrost soil of plateau and filling up the domestic blank.4. The assorted construct mechanization has been researched combining projects. And the author forms a complete set research of effective assorted construct mechanization for permafrost soil of plateau. Through which the face upward work bridge which is anti-interfere get the national patent in 2003.5. With stock option and the engineering test of heat-protecting layer and waterproof layer in tunnel, with the select of primary material, mix ratio, with the select of concrete mix, transportation, maintenance and stripping conditions, the select of assorted equipments and organization of human resource, with quality control and evaluating, the paper studies the construction craft of tunnel lining and waterproof and heat-protecting layer of tunnel in plateau and very-cold conditions. Successful experiences are use for reference to similar tunnels construction.6. In the course of excavation of the mountain tunnel of the Kunlun, the temperature on the country rock surface have been surveyed according to different point, such as on vault, joining the waist , joining the foot, in the wall; or according to different time, such as at zero hour, eight o'clock and sixteen o'clock. And the result has been analyzed and researched. This fills up the domestic blank.7. Aim at season-freeze at part sections of heat-preservation drain in the built Kunlun-tunnel, because of this the drain cannot drain throughout year and part area of it appear leaking water, the paper studies on it. With connectivity tests, the paper analyses and studies on the leaking causation, then establishes corresponding father measure. The measure is validated by spot-engineering testing. After actualizing it, the father measure reached anticipated aim through intuition-observation and geologic radar means. With the administration of the water-leaking of Kunlun-mountain tunnel, this paper has further investigated and analyzed the mechanism of the water-leaking, and has proposed author's original opinion to the question that should notice to similar engineering design.