富水松软岩层冻结法凿井井壁结构试验研究

An experimental study on shift lining structure of frozen shaft in water-rich soft rock

为解决我国西北地区富水松软岩层冻结井筒的支护难题，通过结构模型试验，对冻结井壁的力学特性进行了系统研究。首先推导了井壁结构模型试验的相似准则，据此进行了内、外层井壁的模型设计和试件加工；然后通过加载试验，得到了它们在水平荷载作用下的应力和强度特性。结果表明：高强钢筋混凝土内壁结构中的混凝土处于多轴受压应力状态下，变形受到约束作用明显，井壁结构中混凝土抗压强度比单轴抗压强度提高了1.562~1.831倍，使得井壁实际承载力得到了大幅度提高，并根据理论分析和试验结果推导出了这种井壁承载力的计算公式；外层井壁模型试件在加载破坏时，井壁结构中的混凝土极限压应力接近于混凝土单轴轴心抗压强度。建议在富水松软岩层冻结井壁结构强度计算中，应根据内、外壁结构中混凝土所处的受力状态来选用其强度值。

Aiming at the support problems of frozen shaft in water-rich soft rock of northwest China, the mechanical characteristics of inner and outer shift lining was thoroughly studied by model tests. First, models of inner and outer shift lining were designed, and the specimens were manufactured according to the similarity criterion. Through a loading test, the stress and strength characteristics of inner and outer shift lining structures were obtained. The results indicate that the structure of high strength reinforced concrete inner shift lining is under tri-axial compressive stress state; the distor-tion is evidently restricted; the concrete compressive strength of the shaft lining structure increases 1.562~1.831 times higher than the monomial compressive strength;the actual carrying capacity is increased highly. A formula to calculate the ultimate bearing capacity of the shaft lining is given on the basis of theoretical research and the experimental results. When the specimens of the outer shift lining are loading to failure, the concrete utmost compressive stress of the shaft lining structure is close to the uniaxial axial compressive strength of the concrete. When calculating the strength of fro-zen shaft lining in water-rich soft rock, the strength of the concrete used in inner and outer shaft lin-ing structure should be chosen according to its stress state.