Key Construction Technology Of Bored Pile In Railway Subgrade

Taking the construction of pile foundation in Suzhou east station canopy in Beijing-Shanghai high speed railway as the engineering background, aiming at requirements of the existed high speed railway subgrade soil and complex construction environment such as the tubular pile in subgrade in the construction area,as well as the subgrade during the pre settlement construction, the different construction technique measures need be adopted according to different conditions.Taking into account the construction condition limit, easy hole collapse under the traditional construction, high measurement precision requirement, higher mud processing requirements and so on unfavorable factors, the method of the piles bored in railway subgrade bed surface is researched.The construction projects which can be selected were compared, so as to determine the construction scheme is safe and feasible. three kinds of methods with the reverse circulation drilling construction, rotary drill and hole wall protected by artificial slurry, excavation by the machine were contrasted with technology and economy, then the selected project is as follow: the hole to the upper part of pile in subgrade filled with AB group is bored by the rotary drilling rig, and to the lower part of it consisted of silt soil by combining reverse circulation drill with pile casing, in order to ensure the upper AB group filler is not polluted by the mud, then significantly improving the construction efficiency.By making use of the object internal force interaction theory, according to the actual engineering feature, the internal force effect of collapse hole during the pile bored was analyzed, obtaining to mud weight influence on the collapse hole, and how to reduce the risks of the collapse hole, and to avoid the impact on the roadbed.The internal force analysis of the soil layer is used for the construction of bored piles, and the harm degree of hole collapse during construction was analyzed.According to the different soil, different containing layer, and different position, the possible collapse hole of pile after hole bored was discussed separately, and subgradepollution due to leakage of mud and settlement were predicted, and it was given to verify by combining with the engineering example.