荣浩宇, 李桂臣, 赵光明, 梁东旭, 梁巨理. 不同应力路径下深部岩石真三轴卸荷特性试验[J]. 煤炭学报, 2020, 45(9): 3140-3149. DOI: 10.13225/j.cnki.jccs.2019.0891
引用本文: 荣浩宇, 李桂臣, 赵光明, 梁东旭, 梁巨理. 不同应力路径下深部岩石真三轴卸荷特性试验[J]. 煤炭学报, 2020, 45(9): 3140-3149. DOI: 10.13225/j.cnki.jccs.2019.0891
RONG Haoyu, LI Guichen, ZHAO Guangming, LIANG Dongxu, LIANG Juli. True triaxial test study on mechanical properties of deep rock mass in different stress paths[J]. Journal of China Coal Society, 2020, 45(9): 3140-3149. DOI: 10.13225/j.cnki.jccs.2019.0891
Citation: RONG Haoyu, LI Guichen, ZHAO Guangming, LIANG Dongxu, LIANG Juli. True triaxial test study on mechanical properties of deep rock mass in different stress paths[J]. Journal of China Coal Society, 2020, 45(9): 3140-3149. DOI: 10.13225/j.cnki.jccs.2019.0891

不同应力路径下深部岩石真三轴卸荷特性试验

True triaxial test study on mechanical properties of deep rock mass in different stress paths

  • 摘要: 为了研究深部地下工程施工过程中,受开挖扰动影响下深部岩石的变形破坏特性,以砂岩为研究对象,采用真三轴扰动卸荷岩石测试系统,分别进行真三轴压缩试验、恒轴压单面卸荷试验、增轴压单面卸荷试验与降轴压单面卸荷试验,分析了深部岩石在不同应力路径下的变形破坏特征及力学参数演化规律。研究结果表明:三轴压缩条件下,岩石变形表现为轴向压缩以及沿最小主应力方向扩容,破坏模式为剪切破坏,破坏原因为外部载荷不断增大超过岩石承载能力。卸荷条件下,变形表现为沿卸荷方向强烈扩容,破坏原因为卸荷面荷载不断减小使岩石承载能力不断降低最终小于所受外部载荷,破坏模式为张剪复合破坏。不同卸荷路径下,最大主应力σ1变化对岩石变形破坏影响显著,增轴压路径下,卸载卸荷面应力的同时增加σ1,加剧岩石应变能的释放,破坏更剧烈。而卸轴压路径下,σ1的减小降低卸荷面应力变化对岩石变形破坏的影响岩石,岩石破坏变形过程相对较平缓,岩石破坏主要是因为卸除卸荷面应力使岩石承载能力降低速率大于外部载荷降低速率。三轴压缩条件下,随σ1增大,岩石变形模量E不断减小,泊松比μ不断增加,且变化速率随σ3增大而降低。卸荷条件下,E随卸荷的进行不断减小,μ不断增大,在临近破坏时变形参数劣化速率迅速增大。在卸荷条件下,岩石承载能力随着卸荷面应力的减小而不断减小,增轴压路径下卸荷的同时增大σ1促进了岩石内部裂隙的萌生扩展,岩石承载强度降幅最大,而卸轴压路径下,σ1的降低在一定程度上抑制了裂隙的扩展,岩石承载强度降幅相对较小。

     

    Abstract: To study the deformation and failure characteristics of deep rock under the influence of excavation disturbance during the construction of deep underground engineering,the true triaxial compression test,constant axial pressure single side unloading test,augmented axial pressure single side unloading test and reduced axial pressure single side unloading test were conducted using the true-triaxial testing system for characteristic of rock disturbance and unloading. The deformation and failure characteristics of deep rock under different stress paths and the evolution law of mechanical parameters are analyzed by load test. The results show that:① Under triaxial compression,rock deformation is characterized by axial compression and dilatation along the direction of minimum principal stress σ3. The failure mode is shear failure. The failure reason is that the external load increases continuously and exceeds the bearing capacity of rock. Under unloading conditions,the deformation shows a strong expansion along the unloading direction. The failure reason is that the load on unloading surface decreases continuously,so that the bearing capacity of rock decreases continuously,and ultimately less than the external load. The failure mode is tension-shear composite failure. ②Under different unloading paths,the change of maximum principal stress σ1 has a significant impact on rock deformation and failure. Under the augmented axial compression path,the stress of unloading and unloading surface increases σ1 at the same time,which intensifies the release of rock strain energy and causes more severe damage. Under the unloading path,the decrease of σ1 reduces the influence of stress change on rock deformation and failure. The process of rock failure and deformation is relatively smooth. The main reason for rock failure is that unloading surface stress reduces rock bearing capacity faster than external load reduction rate. ③ Under triaxial compression,with the increase of σ1 ,rock deformation modulus E decreases,Poisson’ s ratio μ increases,and the change rate decreases with the increase of σ3. Under unloading conditions,E decreases with unloading,while μ increases continuously,and the deterioration rate of deformation parameters increases rapidly near failure. ④ Under unloading conditions,rock bearing capacity decreases with the decrease of stress on unloading surface. While unloading under augmented axial compression path,increasing σ1 promotes the initiation and expansion of cracks in rock,and the decrease of rock bearing strength is the largest. Under unloading axial compression path,the decrease of σ1 inhibits the expansion of cracks to a certain extent. The decrease of bearing strength of stone is relatively small.

     

/

返回文章
返回