三排管非均质冻结壁弹塑性分析

Elastic and Plastic Analysis of Heterogeneous Frozen Soil Wall of Triple-row Piped Freezing

为了分析深厚冲积层三排管冻结壁的力学特性,根据冻土弹性模量E、黏聚力c与冻结温度之间的函数关系以及三排管冻结壁的梯形-抛物弓等效温度场模型,将冻结壁视为材料性质沿着径向呈分段函数变化规律的厚壁圆筒,推导出了三排管非均质冻结壁的弹性区与塑性区应力的解析表达式,并给出了冻结壁承载力与塑性区相对半径之间的关系。根据淮南某矿区冻土的力学参数,利用提出的三排管非均质冻结壁计算方法对该矿区进风井冻结壁进行了力学特性分析,计算结果表明:三排管非均质冻结壁的径向应力随着相对半径r的增大而增加,而环向应力在冻结区间Ⅰ,Ⅱ,Ⅲ呈现不同的变化规律。对比分析三排管均质与非均质冻结壁的承载力计算结果可知,利用均质冻结壁计算方法得出的弹性极限承载力计算结果偏大,因此基于该结果的冻结壁设计方法存在一定的风险性,而非均质冻结壁的计算结果更加符合冻结壁实际的受力情况。研究成果可为深厚冲积层多排管冻结壁的设计提供一定的理论参考。

In the light of the functional relationship between freezing temperature and elastic modulus E and cohesion c and by the aid of the trapezoid-parabola equivalent temperature field model,the analytical expressions of stress in elastic and plastic zones of triple-row-piped heterogeneous frozen soil wall were derived based on the assumption that the frozen wall is a thick cylinder with its material properties varying in segmented function along radial direction.The relationship between the bearing capacity of frozen wall and the relative radius of plastic zone was also given.Such calculation theories were applied to the mechanical property analysis for a frozen soil wall in a mine area of Huainan City.Results unveiled that the radial stress of the heterogeneous triple-row-piped frozen soil wall increased with the expansion of relative radius r,while circumferential stress in theⅠ,ⅡandⅢintervals changed in different laws.Calculation results also demonstrated that the elastic ultimate bearing capacity of homogeneous frozen soil wall was too large,which is risky in design.Therefore,the calculation result of heterogeneous frozen soil wall was more consistent with the actual stress condition of frozen wall.The research findings offer important theoretical reference for the design of multi-row freezing in deep alluvium.