Experimental Study On The Friction Moment Between The Screw Of The Self-walking Tunnel Boring Machhine And The Soil

At present, the construction of underground engineering will be a lot of trouble when constructing in the ground based buildings or underground tunnel between buildings and structures. Trenchless construction technique is now widely used, but such as shield construction method and long distance pipe jacking method is difficult to meet the construction requirements of the underground space of turning, which makes the urban underground pipe network construction and development of underground space limited. Aiming at the shortage of the shield and pipe jacking method in construction, making the screw pull self-propelled tunnel boring machine is born.This paper introduces the application 、 research status and the jacking force calculation theory of existing construction technology which has the same using but principle is different, shield method, pipe jacking method, the earth self-walking tunnel boring machine and so on, also analyses and introduces the working mechanism of the screw anchor which principle similar but uses different and its mounting torque experimental study. The screw transmission principle and the working mechanism of the screw propeller are also analyzed. The main content of this paper is to analyze and study the friction moment between the screw and the soil when the boring machine is moving, through simplifying the process of the pull screw structure, then deduce the formulas of the pull screw friction moment. Through comparing the field test results with the theoretical value and the analysis of the test data, the main draw the following conclusions:(1) Two pull screw synchronous counter rotating is the key to make the boring machine walks by itself;(2) As to the soil of the test site, the screw with a shaft can provide greater traction force;(3) In a certain range, with the increase of the length of the screw is screwed into the soil, the pull screw friction moment is increasing;(4) While the boring machine is walking, the change tendency of the two pull screw friction moment is consistent;(5) The extrusion compacting effect of the soil increased the pull screw friction;(6) The test values of the pull screw friction moment and the theoretical values the pull screw friction moment are consistent;(7) The results of theoretical analysis and experiment show that spiral transmission principle pull themselves forward is feasible in the construction of the underground tunnel.