中文摘要：

目的研究高寒地区工程砂岩在冻融循环作用下的破坏机理,解决冷热循环所引起的冻土工程问题.方法通过冻融循环试验,利用超声波检测技术,从岩样的构造特征、矿物组成的角度,对饱和砂岩在冻融循环作用下的破坏机理进行了分析.结果未经冻融的砂岩孔隙率增加了0.9%,表明冻融初期水对砂岩胶结物有溶蚀作用.经过5次左右冻融循环的砂岩孔隙率增加了8.3%,占总增加量的80%,纵波幅值下降73 m V,占总下降量的64%,弹性模量下降576 MPa,占总下降量的76%.表明冻融初期,主要是水结冰的冻胀作用产生周期性荷载,使得孔隙联通,形成大的裂隙;而冻融后期,冻胀作用产生的变形大部分为弹性变形,冻胀的作用效果减弱.结论工程环境中的水通常具有一定的化学成分,会与砂岩发生化学作用,促进损伤的发展.砂岩的损伤主要是孔隙水结冰的冻胀力引起的,当冻胀力超过砂岩抗拉强度时,新的裂隙会产生,只有当下次冻融时冻胀力大于前次冻胀力时,裂隙才会继续发展.

英文摘要：

In order to solve problems of engineering frozen soil caused by freeze-thaw cycles,this paper studied the failure mechanism of the engineering sandstone under effects of freeze-thaw cycles in the alpine region. Based on the structural characteristic of the rock sample and the mineral composition,the failure mechanism of saturated sandstone under freezing and thaw ing cycles were analyzed through freeze-thaw cycle tests with the ultrasonic technology. Results show that the porosity of the sandstone without thaw ing is increased by 0. 9%,which means that in the freeze-thaw cycles,water can corrode the sandstone cements at the beginning of the freezing thaw ing. After five freeze-thaw cycles,the porosity of the sandstone is increased by 8. 3% which takes 80% of the to-tal increased amount,and the vertical amplitude value decreases 73 m V which takes 64% of the total decreased amount,and elastic modulus decreases 576 MPa which is 76% of the total decreased amount. It show s that in the early freeze-thaw,the pores are mainly unicomed,because the periodic load produced by the water frost frozen that leads to forming large fissures; while at the late period,the majority of deformation produced by the frost heaving action is elastic,which can weaken the role of the frost. The damage of the sandstone is mainly caused by the sandstone pore water freezing frost heave force,when the frost heaving force exceeds the tensile strength of the sandstone,new cracks will be generated,and only when the next freezing frost heaving force is greater than the previous force,the cracks can be further developed. Conclusion is that the water in the engineering environment generally has a certain amount of chemical components,which can react with the sandstone and lead developing of its injury.