特厚表土层双层钢板高强高性能混凝土钻井井壁试验研究

EXPERIMENTAL STUDY ON SHIFT-BORING LINING OF HIGH PERFORMANCE CONCRETE AND DOUBLE STEEL CYLINDER IN SUPER-DEEP ALLUVIUM

针对500～700m特厚表土中钻井井筒的支护难题,认为合理的解决途径是采用双层钢板高强高性能混凝土复合井壁结构。首先,给出钻井井壁C60～C75高强高性能混凝土的优化配合比;然后,根据相似理论,进行双层钢板高强高性能混凝土复合井壁结构的模型设计。通过模型试验,对这种井壁结构的应力、变形特性和强度特征进行研究,研究结果表明:由于内、外钢板筒的约束作用,井壁结构中的混凝土完全处于三轴受压应力状态下,其抗压强度得到较大程度的提高,且井壁破坏时混凝土的极限压应变达到-4600με,表现出较好的延性特性,得到了该种井壁结构承载力的试验值,从而为该种高强井壁结构的工程应用提供了设计依据。目前,该研究成果已应用于3个特厚表土层的钻井井筒工程实践中。

Aiming at the supporting problem of the shaft-boring in the deep alluvium of 500700 m,the composite shaft lining of high strength and high performance concrete and double steel cylinder is presented. Firstly,the optimized mixture ratio of the shaft-boring lining C60C75 high strength and high performance concrete is given. Then,according to similarity theory,the model design of the composite shaft lining of high and strength high performance concrete and double steel cylinder is done. Through model experiments,the characteristics of stress and strength of the composite shaft lining of and high strength high performance concrete and double steel cylinder are studied. The results indicate that the concrete bearing strength increases greatly under triaxial compressive stresses states between inner and outer steel plate cylinders. The concrete utmost compressive strain achieves -4 600 με and the shaft lining is fairly ductility when it is damaged. Thus,the results can provide a design basis for engineering practice of this shaft lining structure. Now the study results have been applied to three shaft-borings in the alluvium.