深部冻结井壁早期温度应力计算方法研究

Study on the Calculation Method of Early Temperature Stress of Deep Frozen Shaft Wal

为了研究不同时间节点深部冻结井壁早期温度应力变化规律,基于热传导原理与热弹性力学理论,推导了考虑冻结井壁温度演化过程与混凝土弹性模量变化的冻结井筒内壁早期温度应力解析解。以红庆河煤矿一号风井1.7 m厚壁座为例,分析了冻结井筒内壁早期温度应力的分布规律,确定了造成早期温度应力导致井壁裂缝高风险区的主要原因。研究表明:①早期径向应力σr整体表现为压应力,σr最大可达-2.2 MPa,且总体沿冻结壁向井壁内缘方向逐渐减小;在井壁任一位置处,σr随着龄期的发展呈现先减小后增大的规律;②早期环向应力σθ整体表现为压应力,σθ最大可达-8.98 MPa,趋向冻结壁时,σθ先迅速减小;趋向内壁缘时,σθ先增大后减小;③早期竖向应力σz表现为压应力,σz最大可达-19.64 MPa,且整体随着龄期发展呈现先快速增大而后缓慢减小的规律;④建议未来进行冻结井壁温度应力理论计算时,应根据工程类比法,拟合出同类井壁温度演化过程公式进行求解。在上述分析的基础上,提出了降低冻结井壁破裂风险的相关措施:①减小井壁外缘侧与中心、内缘之间的温差;②制备适用于冻结井筒的抗裂型混凝土。

In order to study the early temperature stress variation law of deep frozen shaft wall at different time nodes,an analytical solution of early temperature stress of frozen shaft wall was derived based on the heat conduction principle and thermoelastic mechanics theory,considering the temperature history of frozen shaft wall and the change of concrete elastic modulus.Taking the 1.7 m thick wall seat of No.1 air shaft in Hongqinghe Coal Mine as the study example,the distribution law of early temperature stress in the inner wall of frozen shaft was obtained,and the main reason of early temperature stress leading to high risk area of shaft fracture was determined.The study results show that:①In the early stage,the radial stressσr is compressive stress as a whole,and the maximumσr can reach-2.2 MPa,and decreases gradually along the frozen wall to the inner edge of the shaft wall.At any position of the borehole wall,σr decreases first and then increases with the development of age.②In the early stage,the annular stressσθis compressive stress as a whole,and the maximumσθcan reach-8.98 MPa.When it tends to the frozen wall,σθdecreases rapidly first.When tending to the inner wall edge,σθincreases first and then decreases.③In the early stage,the vertical stressσz is compressive stress,which can reach the maximum of-19.64 MPa,and increases rapidly at first and then decreases slowly with the development of age.④It is suggested that the temperature history formula of the same kind of shaft wall should be fitted according to the engineering analogy method for the theoretical calculation of temperature stress of frozen shaft wall in the future.On this basis,the measures to reduce the risk of rupture of frozen borehole wall are put forward,including two ideas:①Reduce the temperature difference between the outer edge of borehole wall and the center and the inner edge.②Prepare crack resistant concrete suitable for freezing wellbore.