Study on the mechanical properties and fracture mechanism of hollow?cylinder sandstone under lateral unloading conditions
LI Kesheng1，LIU Chuanxiao2，ZHANG Minzhen3
(1. State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering，China University of Mining and Technology，Xuzhou，Jiangsu 221116，China；2. College of Water Conservancy and Civil Engineering，Shandong Agricultural University，Tai'an，Shandong 271018，China；3. Civil and Resource Engineering School，University of Science and Technology Beijing，Beijing 100083，China)
Abstract：To analyze the impact of excavation unloading on the stability of the surrounding rock in existing deeply buried tunnels，the study utilized conventional triaxial compression tests and lateral unloading tests on hollow-cylinder sandstone specimens，simulating the mechanical behavior and fracture mechanisms of circular tunnels under complex stress conditions. Initially，stress-strain curves of hollow-cylinder sandstone under various confining pressures obtained from indoor mechanical tests were analyzed to assess the impact of confining pressure on mechanical properties. Subsequently，the effects of unloading rate and stress level on the strength deformation characteristics and energy evolution laws of hollow-cylinder sandstone were detailed，based on the stress-strain curves of rock samples under lateral unloading. Finally，the multi-scale fracture mechanisms of hollow-cylinder sandstone under lateral unloading were discussed through observations using cameras and micron-scale industrial CT on the failed specimens. The results showed that both the peak strength and elastic modulus of hollow-cylinder sandstone increased with confining pressure，with peak strength being more sensitive to confining pressure than the elastic modulus. As the unloading rate increased，the peak strength and damage threshold of hollow-cylinder sandstone showed a non-linear decreasing trend，while the Young?s modulus remained essentially unchanged，and the elastic energy and dissipated energy at the peak stress decreased. With increasing unloading stress levels，the peak strength and damage threshold of hollow-cylinder sandstone showed non-linear and linear growth，respectively，with no significant change in Young?s modulus，but an increase in elastic energy and dissipated energy at the peak stress. Under conventional triaxial compression，hollow-cylinder sandstone exhibited shear failure，and with increased confining pressure，the fracture angle decreased while the degree of fracturing for internal wall increased. Under the same confining pressure，as the unloading rate increased or the unloading stress level decreased，the surface fracturing of the hollow-cylinder sandstone was severe while the fracturing damage of internal wall weakened. The crack rate in the failed hollow-cylinder sandstone was directly proportional to both the unloading rate and the stress level. The study’s conclusions provide insights into the failure and instability mechanisms of the surrounding rock in deeply buried tunnels/roadways under lateral unloading conditions.
李克升1，刘传孝2，张敏真3. 侧向卸荷条件下砂岩孔道试样的力学特性及破坏机制研究[J]. 岩石力学与工程学报, 2025, 44(4): 881-897.
LI Kesheng1，LIU Chuanxiao2，ZHANG Minzhen3. Study on the mechanical properties and fracture mechanism of hollow?cylinder sandstone under lateral unloading conditions. , 2025, 44(4): 881-897.
[1] 贾 伟，李 尧，郭张龙，等. 洛川隧道围岩变形规律模型试验研究[J]. 岩土工程学报，2024，46(增1)：164–169.(JIA Wei，LI Yao，GUO Zhanglong，et al. Model tests on soil deformation of surrounding soil of Luochuan tunnel[J]. Chinese Journal of Geotechnical Engineering，2024，46(Supp.1)：164–169.(in Chinese))
[2] 苏国韶，胡李华，冯夏庭，等. 低频周期扰动荷载与静载联合作用下岩爆过程的真三轴试验研究[J]. 岩石力学与工程学报，2016，35(7)：1 309–1 322.(SU Guoshao，HU Lihua，FENG Xiating，et al. True triaxial experimental study of rockburst process under low frequency cyclic disturbance load combined with static load[J]. Chinese Journal of Rock Mechanics and Engineering，2016，35(7)：1 309– 1 322.(in Chinese))
[3] KANG HP，LI WZ，GAO FQ，et al. Grouting theories and technologies for the reinforcement of fractured rocks surrounding deep roadways[J]. Deep Underground Science and Engineering，2023，2(1)：2–19.
[4] 胡 辉，田浩晟，杨文波，等. 高地应力挤压性围岩隧道交叉段变形及结构力学特性研究[J]. 岩石力学与工程学报，2024，43(8)：1 952–1 965.(HU Hui，TIAN Haosheng，YANG Wenbo，et al. Study on deformation and structural mechanics characteristics of intersection sections in high stress ground squeezing surrounding rock tunnels[J]. Chinese Journal of Rock Mechanics and Engineering，2024，43(8)：1 952–1 965.(in Chinese))
[5] 贾 宁，刘 顺，王洪播. 压缩空气储能人工硐库热力耦合解析方法研究[J]. 岩土力学，2024，45(8)：2 263–2 278.(JIA Ning，LIU Shun，WANG Hongbo. Analytical methods for thermo-mechanical coupling of artificial caverns of the compressed air energy storage[J]. Rock and Soil Mechanics，2024，45(8)：2 263–2 278.(in Chinese))
[6] 伍武星，宫凤强，高明忠，等. 冲击扰动下断面形状对深部隧洞岩爆的影响研究[J]. 岩石力学与工程学报，2024，43(9)：2 257–2 272. (WU Wuxing，GONG Fengqiang，GAO Mingzhong，et al. Study on the influence of cross-section shape on rockburst of deep tunnels under impact disturbance[J]. Chinese Journal of Rock Mechanics and Engineering，2024，43(9)：2 257–2 272.(in Chinese))
[7] 康红普. 我国煤矿巷道围岩控制技术发展70年及展望[J]. 岩石力学与工程学报，2021，40(1)：1–30.(KANG Hongpu. Seventy years development and prospects of strata control technologies for coal mine roadways in China[J]. Chinese Journal of Rock Mechanics and Engineering，2021，40(1)：1–30.(in Chinese))
[8] 董西好，刘 帅，刘 平. 卸荷条件下冻结砂岩力学性质及损伤本构模型研究[J]. 岩石力学与工程学报，2024，43(2)：495–509. (DONG Xihao，LIU Shuai，LIU Ping. Study on mechanical properties and damage constitutive model of frozen sandstone under unloading condition[J]. Chinese Journal of Rock Mechanics and Engineering，2024，43(2)：495–509.(in Chinese))
[9] 马德鹏，周 岩，刘传孝，等. 不同卸围压速率下煤样卸荷破坏能量演化特征[J]. 岩土力学，2019，40(7)：2 645–2 652.(MA Depeng， ZHOU Yan，LIU Chuanxiao，et al. Energy evolution characteristics of coal failure in triaxial tests under different unloading confining pressure rates[J]. Rock and Soil Mechanics，2019，40(7)：2 645–2 652.(in Chinese))
[10] 王 宇，艾 芊，李建林，等. 考虑不同影响因素的砂岩损伤特征及其卸荷破坏细观特性研究[J]. 岩土力学，2019，40(4)：1 341–1 350.(WANG Yu， AI Qian， LI Jianlin，et al. Damage characteristics of sandstone under different influence factors and its unloading failure meso-morphology properties[J]. Rock and Soil Mechanics，2019，40(4)：1 341–1 350.(in Chinese))
[11] 丛 宇，王在泉，郑颖人，等. 不同卸荷路径下大理岩破坏过程能量演化规律[J]. 中南大学学报：自然科学版，2016，47(9)：3 140–3 147.(CONG Yu，WANG Zaiquan，ZHENG Yingren，et al. Energy evolution principle of fracture propagation of marble with different unloading stress paths[J]. Journal of Central South University：Science and Technology，2016，47(9)：3 140–3 147.(in Chinese))
[12] 陈国庆，刘 辉，秦昌安，等. 中部锁固岩桥三轴加卸荷力学特性及裂纹扩展研究[J]. 岩石力学与工程学报，2017，36(5)：1 162–1 173. (CHEN Guoqing，LIU Hui，QIN Chang?an，et al. Mechanical properties and crack model of central rock bridge in triaxial unloading test[J]. Chinese Journal of Rock Mechanics and Engineering，2017，36(5)：1 162–1 173.(in Chinese))
[13] 王瑞红，蒋昱州，李建林，等. 卸荷损伤对节理岩体变形特性影响研究[J]. 岩石力学与工程学报，2016，35(增2)：3 747–3 755. (WANG Ruihong，JIANG Yuzhou，LI Jianlin，et al. Effect of unloading damage on deformation characteristics of jointed rock mass[J]. Chinese Journal of Rock Mechanics and Engineering，2016，35(Supp.2)：3 747–3 755. (in Chinese))
[14] HUANG YH，WU SY，YANG C. Experimental study on the failure behaviors of sandstone specimens with two fissures under triaxial loading and unloading conditions[J]. Engineering Fracture Mechanics，2024，298：109933.
[15] YIN PF，YANG SQ，GAO F，et al. Experimental and DEM simulation study on the mechanical characteristic and strain energy evolution of Longmaxi shale under a confining pressure unloading path[J]. Energies，2023，16(16)：5 960.
[16] 范 浩，王 磊，王连国. 不同应力路径下层理煤体力学特性试验研究[J]. 岩土力学，2024，45(2)：385–395.(FAN Hao， WANG Lei， WANG Lianguo. Experimental study on mechanical properties of bedding coal under different stress paths[J]. Rock and Soil Mechanics，2024，45(2)：385–395.(in Chinese))
[17] 程建龙，杨圣奇，殷鹏飞，等. 复合岩层变形及强度特性卸围压试验研究[J]. 中国矿业大学学报，2018，47(6)：1 233–1 242.(CHENG Jianlong，YANG Shengqi，YIN Pengfei，et al. Experimental study of the deformation and strength behavior of composite rock specimens in unloading confining pressure test[J]. Journal of China University of Mining and Technology，2018，47(6)：1 233–1 242.(in Chinese))
[18] 刘泉声，黄 兴，刘建平，等. 深部复合地层围岩与TBM的相互作用及安全控制[J]. 煤炭学报，2015，40(6)：1 213–1 224.(LIU Quansheng，HUANG Xing，LIU Jianping，et al. Interaction and safety control between TBM and deep mixed ground[J]. Journal of China Coal Society，2015，40(6)：1 213–1 224.(in Chinese))
[19] 刘 帅，杨更社. 冻结砂岩侧向卸荷声发射信号及损伤特性研究[J]. 岩石力学与工程学报，2023，42(增2)：4 237–4 247.(LIU Shuai，YANG Gengshe. Study on acoustic emission signal and damage characteristics of frozen sandstone under lateral unloading[J]. Chinese Journal of Rock Mechanics and Engineering，2023，42(Supp.2)：4 237–4 247.(in Chinese))
[20] 徐鼎平，郭广涛，夏跃林，等. 高应力强卸荷下双江口花岗岩岩爆中间主应力效应宏细观试验研究[J]. 岩土力学，2021，42(9)： 2 375–2 386.(XU Dingping，GUO Guangtao，XIA Yuelin，et al. Macro-meso experimental study of intermediate principal stress effect on rockburst of Shuangjiangkou granite under high stress and strong unloading[J]. Rock and Soil Mechanics，2021，42(9)：2 375–2 386.(in Chinese))
[21] 朱子涵，蔚立元，李景龙，等. 峰前卸荷大理岩变形演化规律及破坏耗能特征[J]. 煤炭学报，2020，45(增1)：181–190.(ZHU Zihan，YU Yiyuan，LI Jinglong，et al. Deformation evolution and dissipated energy characteristics of marble under pre-peak unloading conditions[J]. Journal of China Coal Society，2020，45(Supp.1)：181–190.(in Chinese))
[22] 尤明庆，苏承东. 层理倾角不同的砂岩变形破坏和强度的研究[J]. 河南理工大学学报：自然科学版，2009，28(5)：626–635.(YOU Mingqing，SU Chengdong. Study on the deformation failure and strength of sandstone with various declined bedding[J]. Journal of Henan Polytechnic University：Natural Science，2009，28(5)：626–635.(in Chinese)
[23] 缑 勇，苏承东，秦莞臻. 含孔道大理岩圆柱试样的尺寸效应[J]. 采矿与安全工程学报，2007，24(3)：302–305.(GOU Yong，SU Chengdong，QIN Guanzhen. Size effect of hollowed marble cylinder specimen[J]. Journal of Mining and Safety Engineering，2007，24(3)：302–305.(in Chinese))
[24] 尤明庆，苏承东，缑 勇. 大理岩孔道试样的强度及变形特性的试验研究[J]. 岩石力学与工程学报，2007，26(12)：2 420–2 429.(YOU Mingqing，SU Chengdong，GOU Yong. Experimental study on strength and deformation properties of hollow cylindrical specimens of marbles[J]. Chinese Journal of Rock Mechanics and Engineering，2007，26(12)：2 420–2 429.(in Chinese))
[25] 尤明庆，苏承东. 砂岩孔道试样压拉应力下强度和破坏的研究[J]. 岩石力学与工程学报，2010，29(6)：1 096–1 105.(YOU Mingqing， SU Chengdong. Study of strength and failure of hollow cylinders and rings of sandstone under compression-tension stresses[J]. Chinese Journal of Rock Mechanics and Engineering，2010，29(6)：1 096–1 105.(in Chinese))
[26] YANG S Q. Experimental study on deformation，peak strength and crack damage behavior of hollow sandstone under conventional triaxial compression[J]. Engineering Geology，2016，213：11–24.
[27] 苏承东，李冰洋，吴秋红. 石灰岩孔道试样压缩条件下变形与强度特征的试验研究[J]. 岩石力学与工程学报，2016，35(增1)：2 739–2 748.(SU Chengdong，LI Bingyang，WU Qiuhong. Experimental study on deformation and strength properties of hollow cylindrical specimens of limestone under compression[J]. Chinese Journal of Rock Mechanics and Engineering，2016，35(Supp.1)：2 739–2 748.(in Chinese))
[28] 连帅龙. 厚壁圆筒花岗岩力学特性研究[硕士学位论文][D]. 湘潭：湖南科技大学，2019.(LIAN Shuailong. Study on mechanical properties of thick-walled cylinder granite[M. S. Thesis][D]. Xiangtan：Hunan University of Science and Technology，2019.(in Chinese))
[29] YANG S Q. Fracturing mechanism of compressed hollow?cylinder sandstone evaluated by X?ray Micro?CT scanning[J]. Rock Mechanics and Rock Engineering，2018，51(7)：2 033–2 053.
[30] YANG S Q，YANG Z，JING H W，et al. Fracture evolution mechanism of hollow sandstone under conventional triaxial compression by X-ray micro-CT observations and three-dimensional numerical simulations[J]. International Journal of Solids and Structures，2020，190：156–180.
[31] 李夕兵，吴秋红，董陇军，等. 含充填物的厚壁圆筒砂岩的力学性质研究[J]. 岩土工程学报，2015，37(12)：2 149–2 156.(LI Xibing，WU Qiuhong，DONG Longjun，et al. Mechanical property of thick-walled hollow cylinders of sandstone with filling[J]. Chinese Journal of Geotechnical Engineering，2015，37(12)：2 149–2 156.(in Chinese))
[32] 吴秋红，李夕兵，赵伏军，等. 石灰岩孔道试样孔内卸压条件下破坏特征的研究[J]. 岩石力学与工程学报，2017，36(6)：1 424–1 433. (WU Qiuhong，LI Xibing，ZHAO Fujun，et al. Failure characteristics of hollow cylindrical specimens of limestone under hole pressure unloading[J]. Chinese Journal of Rock Mechanics and Engineering，2017，36(6)：1 424–1 433.(in Chinese))
[33] 王 宇，杨浩男，易雪枫，等. 增幅疲劳荷载作用下含双裂隙花岗岩空心圆柱破裂演化试验研究[J]. 岩石力学与工程学报，2022，41(7)：1 325–1 337.(WANG Yu，YANG Haonan，YI Xuefeng，et al. Investigation on fracture evolution of pre-flawed hollow-cylinder granite under increasing-amplitude cyclic loads[J]. Chinese Journal of Rock Mechanics and Engineering，2022，41(7)：1 325–1 337.(in Chinese))
[34] WANG Y，YANG H N，HAN J Q，et al. Insight into the fracture evolution behavior of pre-flawed hollow-cylinder granite under multi-stage increasing-amplitude cyclic loads：A lab-scale testing[J]. Fatigue Fract Eng Mater Struct，2022，45(1)：285–301.
[35] WANG Y，HAN J Q，XIA Y J，et al. New insights into the fracture evolution and instability warning predication for fissure-contained hollow-cylinder granite with different hole diameter under multi-stage cyclic loads[J]. Theoretical and Applied Fracture Mechanics，2022，119：103363.
[36] 姜 玥，周 辉，卢景景，等. 空心圆柱砂岩真三轴试验研究[J]. 岩土力学，2022，43(4)：932–944.(JIANG Yue，ZHOU Hui，LU Jingjing，et al. True triaxial test on hollow cylindrical sandstone[J]. Rock and Soil Mechanics，2022，43(4)：932–944.(in Chinese))
[37] 姜 玥，周 辉，卢景景，等. 不同应力路径下灰砂岩力学特性与强度参数研究[J]. 岩石力学与工程学报，2019，38(4)：815–824.(JIANG Yue，ZHOU Hui， LU Jingjing，et al. Study on mechanical properties and strength parameters of gray sandstone under different stress paths[J]. Chinese Journal of Rock Mechanics and Engineering，2019，38(4)：815–824.(in Chinese))
[38] 周 辉，姜 玥，卢景景，等. 岩石空心圆柱扭剪试验系统研制[J]. 岩土力学，2018，39(4)：1 535–1 542.(ZHOU Hui，JIANG Yue，LU Jingjing，et al. Development of hollow cylinder torsional apparatus for rock[J]. Rock and Soil Mechanics，2018，39(4)：1 535–1 542.(in Chinese))
[39] JIANG Y，ZHOU H，LU J J，et al. Strength，deformation，and failure characteristics of hollow cylinder sandstone under axial-torsional tests[J]. Bull Eng Geol Environ，2023，82(8)：296.
[40] 姜 玥，邹文栋. 基于PFC3D的空心圆柱灰砂岩宏细观参数相关性研究[J]. 煤炭科学技术，2024，52(10)：78–89.(JIANG Yue，ZOU Wendong. A study on the correlation of macro and microstructural parameters of hollow cylindrical grey sandstone based on PFC3D[J]. Coal Science and Technology，2024，52(10)：78–89.(in Chinese))
[41] YANG S Q，XU S B，LIU Z，et al. Experimental investigation on the triaxial unloading mechanical characteristics of sandstone immersed in different brines[J]. Geomechanics and Geophysics for Geo-Energy and Geo-Resources，2023，9(1)：71.
2025, Vol. 44 
