酸蚀水致灰岩动态弱化机制及试验方法研究  

Experimental study on the dynamic acid water weakening mechanism of limestone

作　　者：唐红梅[1] 周福川 宋刚 杨健 毛柯洁 苗梦琦 TANG Hongmei;ZHOU Fuchuan;SONG Gang;YANG Jian;MAO Kejie;MIAO Mengqi(Institute of Geotechnical Engineering,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]重庆交通大学岩土工程研究所,重庆400074

出　　处：《岩石力学与工程学报》2023年第6期1312-1324,共13页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51678097,51378521)。

摘　　要：水致弱化函数是岩体长期稳定性分析和失稳预测的重要参数。通过机制分析,提出表征溶蚀型碳酸盐岩强度劣化特征的动态水致弱化函数。岩矿分析和扫描电镜实验揭示:茅口组灰岩的方解石矿物含量达99.6%以上,酸蚀作用难以改变物质组分的占比,但可加剧溶蚀孔、洞、隙增生,进而削弱灰岩强度。由力学试验获取了峰值抗压强度和动态软化系数,酸蚀后的灰岩单轴抗压强度降幅介于50.8%~57.2%,其劣化程度高于其他应力状态;动态软化系数随酸蚀时间增加而降低,其时效性特征对岩体长期稳定性有不利影响。由水理性试验获取了酸蚀率、自由吸酸率、饱和吸水率和动态饱和度等指标,揭示了酸度和酸蚀时间对灰岩溶蚀差异性的影响,酸度起主控作用,但弱酸环境下,酸蚀时间决定灰岩的劣化进程。动态水致弱化函数在强酸环境下(pH=2)的降幅梯度明显大于弱酸环境(pH=6),其拟合公式的预测数据与试验结果的最大误差小于10%。研究成果可为溶蚀型岩体劣化研究和地质灾害防治提供重要支撑。The water weakening function is essential for long-term stability analysis and instability prediction of rock mass.Based on the mechanism analysis,a dynamic water weakening function to characterize the strength deterioration of dissolved carbonate rocks is proposed.X-Ray diffraction(XRD)of the rock mineral and scanning electron microscopy(SEM)experiments reveal that the calcite mineral content of Maokou Formation limestone is more than 99.6%.The acid etching can hardly change the proportion of material components but can aggravate the growth of dissolution pores,holes,and gaps and weaken the strength of limestone.The uniaxial compressive strength and dynamic softening coefficient were obtained from mechanical tests.The uniaxial compressive strength of the acid-etched limestone decreased between 50.8%and 57.2%,and its deterioration degree was higher than that of other stress states.The dynamic softening coefficient decreases with the increased etching time,which negatively affects the long-term stability of rock mass.The acid erosion rate,free acid absorption rate,saturated water absorption rate,and dynamic saturation were obtained from the water physical properties experiment,which revealed the influence of acidity and acid etching time on the difference in limestone dissolution.Acidity plays a primary role,but acid etching time determines the deterioration process of limestone in a weak acid environment.The decrease gradient of the dynamic water weakening function in the strong acid environment(pH=2)is significantly larger than that in the weak acid environment(pH=6),and the maximum error between the predicted data of the fitting formula and the experimental results is less than 10%.The research results can provide critical support for studying dissolution rock mass deterioration and preventing and controlling geological disasters.

关 键 词：岩石力学 灰岩 动态水致弱化函数 抗压强度试验 水理性试验 时间效应 

分 类 号：TU45[建筑科学—岩土工程]