考虑冻胀特性的多冷媒非均质人工冻结壁弹塑性分析

ELASTOPLASTIC ANALYSIS OF MULTI-REFRIGERANT HETEROGENEOUS FROZEN WALL CONSIDERING FROST HEAVE CHARACTERISTICS

  • 摘要: 为了合理分析多冷媒非均质人工冻结壁的力学特性,将冻结壁视为弹性模量和黏聚力随半径呈线性变化的功能梯度材料,并通过引入冻胀系数n来反映冻结壁的冻胀特性,基于不同屈服准则分别推导得出考虑冻胀特性的多冷媒非均质人工冻结壁弹塑性状态下的应力、位移以及塑性区相对半径的隐式方程。计算结果表明:在考虑非均质特性后,基于M-C、D-P、广义Tresca以及双剪统一强度准则计算得出冻结壁的弹性极限承载力分别降低4.01%、4.02%、3.19%、2.57%,而塑性极限承载力分别提高8.13%、8.13%、8.04%、7.95%;进一步考虑冻胀特性后,基于四种屈服准则计算得出非均质冻结壁的弹性极限承载力分别提高6.91%、6.92%、5.93%、5.19%。以M-C准则为例,考虑冻胀特性后,当冻结壁处于弹性极限状态(rc=1)时,非均质冻结壁内、外缘位移分别增加3.850 cm和17.159 cm;当冻结壁处于弹塑性状态(rc=1.2)时,非均质冻结壁内、外缘位移分别增加5.544 cm和16.024 cm;当塑性区相对半径1≤rc≤1.2时,内缘位移随着塑性区的增大而增大,外缘位移则是先减小后增大。相较于均质冻结壁,非均质冻结壁在相同的塑性区扩展半径下展现出更高的承载力,并且这种差异随着塑性区半径的增加以及冻胀特性的影响变得更加突出。该研究对于富水地层多冷媒冻结壁的设计具有重要的参考意义。

     

    Abstract: In order to reasonably analyze the mechanical properties of the multi-refrigerant heterogeneous artificial frozen wall, the frozen wall is regarded as functionally graded material whose elastic modulus and cohesion change linearly with the radius, and the frost heave coefficient n is introduced to reflect the frost heave characteristics of the frozen wall. Based on different yield criteria, the implicit equations of stress, displacement and relative radius of plastic zone of multi-refrigerant heterogeneous artificial frozen wall in elastoplastic state are derived respectively. The calculation results show that after considering the heterogeneity characteristics, the elastic ultimate bearing capacity of frozen wall calculated based on M-C, D-P, generalized Tresca and twin shear unified strength criterion is reduced by 4.01%, 4.02%, 3.19% and 2.57%, respectively, while the plastic ultimate bearing capacity is increased by 8.13%, 8.13%, 8.04% and 7.95%, respectively. After further considering the frost heave characteristics, the elastic ultimate bearing capacity of the heterogeneous frozen wall is calculated based on the four yield criteria, which is increased by 6.91%, 6.92%, 5.93% and 5.19%, respectively. Taking the M-C criterion as an example, considering the frost heave characteristics, when the frozen wall is in the elastic limit state (rc = 1), the displacement of the inner and outer edges of the heterogeneous frozen wall increases by 3.850 cm and 17.159 cm, respectively. When the frozen wall is in the elastoplastic state (rc = 1.2), the displacement of the inner and outer edges of the heterogeneous frozen wall increases by 5.544 cm and 16.024 cm, respectively. When the relative radius of the plastic zone is 1 ≤ rc ≤ 1.2, the displacement of the inner edge increases with the increase of the plastic zone, and the displacement of the outer edge decreases first and then increases. Compared with homogeneous frozen wall, the heterogeneous frozen wall exhibits higher bearing capacity at the same plastic zone expansion radius, and this difference becomes more prominent with the increase of plastic zone radius and the influence of frost heave characteristics. This study has important reference significance for the design of multi-refrigerant frozen wall in water-rich strata.

     

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