超低温作用下花岗岩力学特性及地下LNG储库稳定性研究  

Mechanical properties of granite under ultra-low temperature and stability of underground LNG storage facilities

作　　者：李纯纯 熊峰 张国华 华东杰 曹伟腾 唐志成 LI Chunchun;XIONG Feng;ZHANG Guohua;HUA Dongjie;CAO Weiteng;TANG Zhicheng(China University of Geosciences(Wuhan),Engineering of Faculty,Wuhan 430074,China;Chang'an University,Key Laboratory of Highway Bridge and Tunnel Engineering,Xi'an 710064,China;China University of Geosciences(Wuhan),Key Laboratory of Geological Survey and Evaluation of Ministry of Education,Wuhan 430074,China)

机构地区：[1]中国地质大学(武汉)工程学院,湖北武汉430074 [2]长安大学陕西省公路桥梁与隧道重点室验室,陕西西安710064 [3]中国地质大学(武汉)地质探测与评估教育部重点实验室,湖北武汉430074

出　　处：《岩土工程学报》2025年第4期840-848,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金面上项目(52209148);国家重点研发计划项目课题(2021YFB2600402)。

摘　　要：花岗岩分布广泛、强度高,是低温液化天然气(LNG)地下存储的理想介质。然而LNG形成的极端低温(-162℃)使得花岗岩岩体性质发生改变,影响储库安全。为了探究超低温下花岗岩力学特性,开展了-90℃~-165℃低温环境下干燥和饱和花岗岩单轴压缩试验、热膨胀测试以及微观观察。试验结果表明,当温度从-90℃降低到-165℃时,饱和花岗岩的抗压强度和弹性模量分别提高31.1%,24%,干燥状态花岗岩的弹性模量提高了12.8%,而抗压强度变化不明显。力学强度提升主要原因在于随着温度的降低,干燥花岗岩因为自身矿物结构低温收缩导致内部颗粒胶结作用增强;饱和花岗岩由于含有孔隙水,遇低温冻结成冰,使岩石空隙与裂纹黏结得更加紧密,岩石内部结构更为致密。通过试验数据建立了岩石线膨胀系数与温度的负相关经验关系式,嵌入到COMSOL的热-力耦合模型中,实现了低温LNG储库长期稳定性分析。随着运营年限增加和温度降低,岩石产生冻胀效应,岩层间发生挤压变形,导致地表出现隆起风险,同时这项研究也对地下岩体空间工程发展具有重要意义。The granite is widely distributed and has high strength,making it an ideal medium for underground storage of low-temperature liquefied natural gas(LNG).The LNG exhibits extremely low temperatures(-162℃),which causes changes in the properties of the granite and affects storage safety.This study aims to investigate the mechanical properties of dry and saturated granite at ultra-low temperatures(-90°C to-165°C)through uniaxial compression,thermal expansion,and microscopic tests.The results show that when the temperature decreases from-90°C to-165°C,the compressive strength and elastic modulus of saturated granite increase by 31.1%and 24%,respectively,while the elastic modulus of dry granite increases by 12.8%without a significant change in the compressive strength.This is attributed to the decrease in temperature,resulting in shrinkage of minerals in the dry granite,which enhances the bonding of internal particles.The presence of pore water in the saturated granite causes it to freeze into ice at low temperatures,resulting in the tighter adhesion of the rock voids and cracks.Consequently,the internal structure of granite becomes denser.Using the test data an empirical formula showing a negative correlation between the rock linear expansion coefficient and the temperature was established.This formula is integrated into the thermal-mechanical coupling model in COMSOL for conducting long-term stability analysis of low-temperature LNG storage.As operating years increase,the surrounding rock of the underground storage will undergo frost heave effects due to temperatures decreases.This can lead to compression deformation between rock layers and risk of surface uplift,while this research is of great significance for the development of underground space engineering.

关 键 词：超低温 花岗岩 单轴压缩试验 微裂纹 冻胀 储库稳定性 

分 类 号：TU43[建筑科学—岩土工程]