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岩体冻融损伤机制为温度降低使岩体中的水发生相变、体积膨胀、产生冻胀力的作用,岩体中的微裂隙在冻胀力的作用下扩展延伸,温度升高时,融化的水进入新的裂隙,冻结成冰再次产生冻胀作用,反复循环使裂隙网络扩展,最终造成岩体的损伤。基于此,从弹塑性力学、断裂力学的角度出发,研究了在冻胀力的作用下单裂隙扩展特性,推导了冻胀力与裂纹扩展长度之间的关系,利用Mori-Tanaka方法建立了岩体宏观损伤量与冻胀力及冻融次数之间的关系式,讨论了岩体弹性模量与冻融次数、冻胀应力以及渗透系数的变化规律,并与试验结果进行了比较分析。结果表明,岩体在冻融循环条件下的弹性模量随冻融次数的增加呈非线性减小;冻胀应力越大,岩体弹性模量衰减越快;岩体的渗透系数越大,弹性模量衰减越慢。
The freezing and thawing mechanism of the rock mass is that the temperature decreases to make the water in the rock mass undergo phase change and volume expansion to produce the frost heaving force. The micro-cracks in the rock mass expand and extend under the frost heaving force. When the temperature rises, Melted water into the new cracks, frozen ice again produce frost heaving effect, repeated cycles to expand the network of cracks, eventually resulting in rock mass damage. Based on this, from the point of view of elasto-plasticity and fracture mechanics, the effect of frost heave on the propagation of single fracture was studied, and the relation between the frost heaving force and the crack propagation length was deduced. The Mori-Tanaka method was used to establish the rock The relationship between macro damage quantity, frost heaving force and the number of frost heaving and thawing, the variation of elastic modulus, number of freeze-thaw cycles, frost heaving stress and permeability coefficient of rock mass are discussed and compared with the experimental results. The results show that the elastic modulus of rock mass decreases nonlinearly with the increase of the number of freeze-thaw cycles. The larger the frost heaving stress is, the faster the elastic modulus of rock mass decays. The larger the permeability coefficient of rock mass, The slower the modulus of elasticity decays.