随着深埋隧洞在我国工程建设中数量的日益增加，以及西北地区的特殊地质地貌环境，开挖卸荷和渗流作用两个因素对隧洞围岩岩体稳定性的影响已经成为重点研究问题之一。开挖卸荷作用会促使岩体裂隙扩展，导致岩体被渗流作用侵蚀，高渗水压力在隧洞岩体的开挖卸荷过程中，又会促使岩石内部裂纹的扩展，加剧卸荷岩体的劣化，从而诱发围岩失稳破坏。因此，本文以某水电站上游引水隧洞为背景，综合采用理论分析与试验研究相结合的方法，针对富水区卸荷扰动区围岩体失稳破坏问题，开展了室内物理力学试验，研究了花岗岩在开挖卸荷及渗流作用下的力学特性和渗流特性，阐述了卸荷-渗流作用下花岗岩的破坏机理，结合花岗岩在卸荷−渗流作用下破坏规律，对某水电站上游引水隧洞进行数值模拟，分析引水隧洞围岩在考虑开挖卸荷及渗流作用下的应力场、位移场及渗流场的分布规律，检验了工程的合理性。论文的主要研究内容及成果如下： 
（1）开展不同围压、卸荷量级及渗压下花岗岩的三轴卸荷渗流试验。卸荷花岗岩在峰后阶段大都出现了脆性跌落的特征，破坏岩样基本不再具有残余强度。卸荷岩样由于渗压的增大及轴压的增加，侧向应变和体积应变较大，扩容明显。渗压梯度增大使得卸荷试件出现明显侧向扩容，且岩石在高渗压条件下的破坏更加剧烈，渗压的存在，加快了岩石的破裂进程。岩石裂纹闭合时的环向应变随渗压的增大而增大，渗压促进岩石裂纹的张开扩展，渗压越大，劣化作用越明显。 
（2）岩石裂纹闭合时的应变随渗透压力的增大而增大，说明渗压的存在，抑制了岩石裂纹的压缩闭合。随着渗压的增加，岩石裂纹稳定扩展阶段变短，由于渗压的存在，促进裂纹的进一步扩展所致。岩石起裂应力随渗压的增大而逐渐降低，在低渗压下，围压对岩石的抑制作用较为明显。岩石损伤应力随渗压的增大呈现降低趋势，随着渗压的增长，渗压对岩石的损伤强度影响开始变小。花岗岩在卸荷渗流的作用下，损伤强度受渗压作用降低，而围压在一定程度上延缓了裂纹的扩展，使裂纹非稳定扩展阶段延长。 

（3）当渗压和卸荷量级条件相同时，岩样受高围压应力比低围压应力时岩样渗透系数降低，各级渗透系数随围压增大均呈递减关系。围压的卸荷使得侧向形变进一步加剧，促进了内部裂隙扩展、贯通，从而渗透系数发生突增。在恒定围压下，岩样渗透系数随渗透压力的增大而增大，且渗透压力越大，渗透系数增长越明显。随着岩样侧向压力的减小，岩样产生一定的变形，使得岩样内部裂纹随偏应力的增大而逐步扩展，岩样内部渗流 通道增加，致使岩样渗透系数随之增长。渗透率变化与 岩样 体应变呈正相关，岩样 被受力挤压体缩时，体应变降低，内部渗流通道闭合，渗透率随之降低，在卸荷作用下， 岩样 内部裂纹逐渐张开，体应变增长，渗透率随之增长。

（4 ）基于岩体卸荷分区的划分以及卸荷渗流模型的假定，建立开挖卸荷岩体渗流模型，分析了复杂地质条件下引水隧洞开挖卸荷围岩应力场、位移场、塑性区和渗流场。在隧洞中心两侧衬砌外部区域有较大的应力集中现象，在引水隧洞开挖卸荷影响区域以外，竖直总 应力随岩层深度增大而增大。因为总应力场由岩体自重应力与渗压组成，因此总应力场分布大致相同，但是由于隧洞围岩开挖卸荷与渗流作用导致卸荷带区域岩体参数发生变化，导致开挖卸荷区域应力产生变化，从而岩体内部应力场发生重新分布。开挖卸荷以及渗压作用均会使围岩位移变形增长，且卸荷 渗流作用下，会加剧引水隧洞围岩的变形。由于卸荷带渗流系数受开挖影响而增大，渗流场随之改变，隧洞两侧和底部区域受其影响较大，孔隙水压里呈现出明显增大；引水隧洞周围孔隙水压力随埋深增大而增大，且因为卸荷带渗流系数的增大，隧洞附近水压呈现降低趋势。

With the increasing number of deep buried tunnels in China's engineering construction and the special geological and geomorphic environment in the northwest region, the impact of excavation unloading and seepage on the stability of tunnel surrounding rock has become one of the key research issues. The excavation unloading effect will promote the expansion of rock fractures, leading to the erosion of the rock mass by seepage. During the excavation unloading process of the tunnel rock mass, high seepage water pressure will also promote the expansion of internal cracks in the rock, exacerbating the deterioration of the unloading rock mass, and thus inducing the instability and failure of the surrounding rock. Therefore, this article takes the upstream diversion tunnel of a hydropower station in the northwest as the background, and adopts a combination of theoretical analysis and experimental research methods to conduct indoor physical and mechanical tests on the instability and failure of the surrounding rock mass in the unloading and disturbance area of the rich water area. It studies the mechanical and seepage characteristics of granite under excavation unloading and seepage, and elaborates on the failure mechanism of granite under unloading seepage, Based on the failure law of granite under unloading seepage, numerical simulation was conducted on the upstream diversion tunnel of a hydropower station in northwest China. The stress field, displacement field, and seepage field distribution of the surrounding rock of the diversion tunnel were analyzed considering excavation unloading and seepage, and the rationality of the project was tested. The main research content and achievements of the paper are as follows: 

(1) Conduct triaxial unloading seepage tests on granite under different confining pressures, unloading magnitudes, and seepage pressures. The unloading granite mostly exhibits brittle drop characteristics in the post peak stage, and the damaged rock samples no longer have residual strength. Due to the increase in osmotic pressure and axial pressure, the unloading rock sample exhibits significant lateral and volumetric strains, resulting in significant expansion. The increase in seepage pressure gradient results in significant lateral expansion of the unloaded specimen, and the rock failure becomes more severe under high seepage pressure conditions. The presence of seepage pressure accelerates the process of rock fracture. The circumferential strain during the closure of rock cracks increases with the increase of seepage pressure, which promotes the opening and propagation of rock cracks. The greater the seepage pressure, the more obvious the degradation effect. 
(2) The strain of rock crack closure increases with the increase of seepage pressure, indicating that the existence of seepage pressure inhibits the compression closure of rock cracks. With the increase of seepage pressure, the stable propagation stage of rock cracks becomes shorter, which is caused by the presence of seepage pressure promoting further crack propagation. The rock cracking stress gradually decreases with the increase of seepage pressure, and under low seepage pressure, the restraining effect of confining pressure on the rock is more obvious. The rock damage stress shows a decreasing trend with the increase of seepage pressure, and as the seepage pressure increases, the impact of seepage pressure on the rock damage strength begins to decrease. Under the action of unloading and seepage, the damage strength of granite is reduced by seepage pressure, and the confining pressure to a certain extent delays the propagation of cracks, prolonging the unstable propagation stage of cracks. 
(3) When the conditions of seepage pressure and unloading are the same, the permeability coefficient of the rock sample decreases when subjected to high confining pressure stress compared to low confining pressure stress, and the permeability coefficients at all levels show a decreasing relationship with increasing confining pressure. The unloading of confining pressure further intensifies lateral deformation, promotes the expansion and connection of internal cracks, and leads to a sudden increase in permeability coefficient. Under constant confining pressure, the permeability coefficient of rock sample increases with the increase of seepage pressure, and the larger the seepage pressure, the more obvious the permeability coefficient growth. As the lateral pressure of the rock sample decreases, the rock sample undergoes certain deformation, causing internal cracks to gradually expand with the increase of deviatoric stress. The internal seepage channels of the rock sample increase, resulting in an increase in the permeability coefficient of the rock sample. The change in permeability is positively correlated with the volume strain of the sample. When the sample is compressed by force, the volume strain decreases, and the internal seepage channel closes, resulting in a decrease in permeability. Under unloading, the internal cracks of the sample gradually open, and the volume strain increases, leading to an increase in permeability .

(4) Based on the division of rock mass unloading zones and the assumption of unloading seepage model, a excavation unloading rock mass seepage model was established. The stress field, displacement field, plastic zone, and seepage field of the unloading surrounding rock of the diversion tunnel excavation under complex geological conditions were analyzed. There is a significant concentration of stress in the external area of the lining on both sides of the tunnel center. Outside the area affected by the excavation and unloading of the headrace tunnel, the total vertical stress increases with the depth of the rock layer. Because the total stress field is composed of the self weight stress and seepage pressure of the rock mass, the distribution of the total stress field is roughly the same. However, due to the unloading and seepage effects of tunnel surrounding rock excavation, the rock mass parameters in the unloading zone change, resulting in changes in the stress in the excavation unloading area, and thus the stress field inside the rock mass undergoes redistribution. Both excavation unloading and seepage pressure can increase the displacement and deformation of the surrounding rock, and under the unloading seepage effect, it will intensify the deformation of the surrounding rock of the diversion tunnel. Due to the influence of excavation on the seepage coefficient of the unloading zone, the seepage field changes accordingly, and the areas on both sides and bottom of the tunnel are greatly affected, resulting in a significant increase in pore water pressure; The pore water pressure around the diversion tunnel increases with the increase of burial depth, and due to the increase in the seepage coefficient of the unloading zone, the water pressure near the tunnel shows a decreasing trend.