【作者】 徐湘涛；

【导师】 黄润秋；

【作者基本信息】 成都理工大学 ， 岩土工程， 2012， 博士

【摘要】 论文以金沙江白鹤滩水电站高边坡的岩体力学特性及长期稳定性为主题,对研究区的工程地质环境条件和岩体结构特征进行了详细调研和描述,对控制性结构面进行了分级和分类；针对玄武岩岩体开展了加载和卸荷三轴力学试验,获得了玄武岩的三轴力学参数,研究了玄武岩在不同应力条件下的变形破坏规律,建议了玄武岩的本构模型；针对层间、层内错动带开展了压缩剪切流变试验,获得了错动带的流变力学参数,研究了错动带在压缩剪切条件下的变形规律,建立了错动带的黏弹性流变模型；最后在研究白鹤滩水电站高边坡赋存的地应力场规律基础之上,通过数值模拟研究了该高边坡在自然和蓄水条件下的变形和长期稳定性。取得了以下研究成果：(1)地应力Kaiser效应测试、水压致裂法和应力解除法原位测试成果表明：研究区地应力场较为复杂,两岸岸坡的竖直应力大于自重应力、最大水平应力普遍大于竖直应力,研究区岩体地应力是自重应力与构造应力联合作用的结果,且构造应力起控制作用。(2)系统分析了研究区玄武岩的原生建造、构造改造和表生改造形迹,进行了结构面分级、结构面性状分类,建立了相应的分级、分类标准,依据上述标准对研究区的层间、层内错动带、断层、节理裂隙、深部裂缝等结构面进行了分级分类,明确了边坡的控制性结构面。(3)采用恒围增轴、恒轴卸围、卸轴卸围、增轴卸围4种应力路径开展了玄武岩岩体三轴力学试验,获得了玄武岩在加载和卸荷条件下的强度参数、弹性模量和泊松比。分析了玄武岩在加载和卸荷模式下的全过程应力应变曲线,分析了卸围速率和应力路径对力学特性和破坏方式的影响,分析了恒围和卸围模式的能量特征,研究表明高卸围速率和卸围模式下玄武岩表现出更为明显张性破裂特征。(4)采用Mohr-Coulomb强度准则和Hoek-Brown强度准则对玄武岩进行了评价,在低围压下两个准则均对玄武岩的破坏应力状态和破坏机理均具有较好的适宜性。基于全过程应力应变曲线,建立了玄武岩加载模式下的3段式弹脆塑性模型,卸荷模式下的4段式弹屈脆塑型模型,并建议了相应的本构模型。(5)开展了岩块岩屑型和岩屑夹泥型错动带室内无侧限压缩剪切流变试验及相应的残余剪切试验,获得了错动带的长期强度、残余强度等强度参数及剪变模量、黏滞系数等流变参数,并分析了各流变参数的特征和规律,提出了相应的建议值。(6)在分析错动带正应变、剪应变变化规律的基础上,建立了对数型经验本构模型,分析了各经验模型参数的规律。经模型辨识确定错动带在压缩剪切流变条件下呈现黏弹性特征,在高、低应力水平下可分别采用Cvisc、Burgers黏弹性流变模型描述。针对低应力水平下的错动带流变试验,采用Burgers模型进行了非线性回归分析,获得了组合流变本构模型参数,分析了模型参数的变化规律。依据模型参数的回归分析成果,获取了研究区不同类型、不同位置错动带的流变参数。(7)在地质模型概化的基础上建立了白鹤滩水电站高边坡三维数值模型,选用Flac3D软件采用Mohr-Coulomb模型进行了地应力场模拟,经模型验证获得了应力边界条件,分析了地应力场的分布规律。研究区水平应力分量大致以高程700m为界分为上下两段,上段表现为以自重应力为主、同时表现出驼峰应力向岸坡深部转移的现象,下段表现为以构造应力和自重应力为主。(8)选用Flac3D软件对白鹤滩水电站高边坡在自然条件下的流变特性开展了数值模拟研究,分析了岸坡岩体和错动带的应力、塑性区和变形的分布规律。岸坡岩体和错动带的应力一般在流变历时3月后趋于恒定,变形一般在流变历时6月后进入低速率蠕变阶段。左岸岩体变形主要发育于岸坡表部、最大水平位移约为5.15cm,右岸岩体变形主要沿层间错动带C3和C3-1出露部位由表及里逐渐发育、最大水平位移约为-5.20cm,断层F14对岸坡岩体和错动带的变形发育具有显著的约束效应。(9)选用Flac3D软件对白鹤滩水电站高边坡在蓄水条件下的流变特性开展了数值模型研究,分析了岸坡岩体、错动带和拱肩槽边坡的应力、塑性区和变形的分布规律。岸坡岩体和错动带的应力一般在3月后趋于恒定,变形一般在6月后进入低速率蠕变阶段。研究区左岸岩体最大变形域位于勘Ⅸ～Ⅹ2线、断层F14下游岸坡表部,最大水平位移约为6.4cm,断层F14对该变形域的发育有一定的约束作用；右岸岩体变形域基本沿层间错动带C3和C3-1出露部位由表及里发育,最大变形域位于断层F20上游、层间错动带C3和C3-1出露部位,最大水平位移约为-6.9cm。在蓄水流变过程中,拱肩槽边坡逐步进行着应力调整和变形协调,在流变历时6月后基本趋于恒定,左岸坝肩边坡岩体水平位移最大值位于拱坝顶部834m高程,右岸坝肩边坡岩体水平位移最大值位于680m高程。更多还原

【Abstract】 Relying on the project of Jinsha River Baihetan hydropower station, scientific researches were as the topic of the dissertation about rock mass mechanical characteristics and long term stability of the high slope. Based on the field investigation, engineering geological environmental conditions and rock mass structure characteristics were surveyed and described in detail, and controlling discontinuities were graded and classified. Tiaxial mechanical experiments of basalt structures were conducted under loading and unloading. According to the tiaxial mechanical experiments, mechanics parameters of basalt structures were obtained, deformation and failure rules of basalt structures were researched under different stress conditions, and then constitutive models of basalt structures were advised. Rheological behaviors of controlling shear zones were experimented under compressive shear conditions. Based on rheological experiments, Rheological mechanical parameters of shear zones were acquired, deformation rules of shear zones were researched under compressive shear conditions, and then rheological model was analyzed and rheological model parameters were identified. Geostress of the high slope was simulated numerically by Flac3D. Stress field distribution rules were analyzed widely. By Flac3D, deformation and long term stability of the high slope were researched under natural conditions and reservoir operation conditions.After systematic research, the dissertation has made the following achievements.(1) Results of indoor and in-situ test have shown that the research area’s geostress is more complicated. The vertical stress is more than the gravity stress. The maximum horizontal stress is generally greater than vertical stress. Geostress is controlled by the gravitational stress and the tectonic stress, and the tectonic stress is dominated. (2) The research area’s geologic evidences was analyzed systematically in terms of original construction, tectonic reworking supergene modification. Discontinuities’ grading and classification criteria were established. On the basis of the grading and classification criteria, shear zones and faults and joint fissures and deep fractures were graded and classified. Then controlling discontinuities of high slope were identified.(3) Tiaxial mechanical experiments of basalt mass structures were carried out. Based on tiaxial mechanical experiments, mechanics parameters of basalt structures were obtained, which consist of strength parameters and elastic modulus and Poisson’s ratio. The stress-strain full curves of basalt mass structures were analyzed under loading and unloading. Effects on mechanical properties and failure modes were analyzed from unloading lateral stress rate and stress path. Energy characteristics of basalt mass structures were analyzed under loading and unloading. Results have shown that basalts show more obvious brittleness under unloading.(4) Basalt mass structures were assessed by Mohr-Coulomb strength criterion and Hoek-Brown strength criterion. Under low lateral stress, the above strength criterions are suitable for basalt mass structures in terms of failure stress state and failure mechanism. On the basis of the stress-strain full curves, constitutive models of basalt mass structures were advised. Basalt mass structures show elastic-brittle-plastic characteristics under loading. Basalt mass structures show elastic-yield-brittle-plastic characteristics under unloading.(5) Compressive shear rheological experiments of shear zones were implemented, which aimed at the types of rock with debris and debris with clay. Then residual shear experiments of shear zones were carried out as well. According to the rheological experiments, rheological mechanics parameters of shear zones were procured, which consists of long term strength and residual strength and shear modulus and viscosity coefficient. Characteristics and rules of rheological mechanics parameters were researched. Then suggested rheological parameters of shear zones were obtained.(6) Based on strain rules of shear zones, a logarithmically experience constitutive model was set up, and then model parameters’ rules were analyzed. By model identification, shear zones show viscoelastic characteristics under compressive shear stress conditions. Under high stress condition, shear zones could be described by Cvisc model. Under low stress condition, shear zones could be described by Burgers model. Most rheological experiments were carried out under low stress condition, and then shear zones were regression analyzed by Burgers model. After model parameters were obtained, their evolutional rules were analyzed. On the basis of the regression analysis results, rheological parameters of Baihetan hydropower station were obtained. (7) Based on generalized geological model, the three-dimensional numerical simulation model of high slope was set up by Ansys. Using Mohr-Coulomb model, Geostress was simulated by Flac3D. After model validation, geostress boundary conditions were obtained and geostress distribution rules were analyzed. Horizontal stress of research area is divided into upper and lower segments bounded by700meters elevation. The upper slope’s geostress come from gravitational stress, and the lower slope’s geostress is comprised of the gravitational stress and the tectonic stress.(8) Under natural conditions, the high slope of Baihetan hydropower station was simulated in rheology by Flac3D. Distributive rules of stress and plastic zone and deformation referring to rock mass and shear zones of the high slope were analyzed. Rock mass and shear zones’stresses would be in stable gradually in3months, and their deformation would be in low speed creep stage in6months. Rock mass’s maximum deformation of the left bank slope would develop gradually in superficial slope. Maximum deformation of the right bank slope would develop gradually along the shear zones C3and C3-1from outside to inside. Faults F14have obviously restraint effects on deformation of rock mass and shear zones.(9) Under reservoir operation conditions, the high slope of Baihetan hydropower station was simulated in rheology by Flac3D. Distributive rules of stress and plastic zone and deformation referring to rock mass and shear zones of the high slope were analyzed. Rock mass and shear zones’stresses would be in stable gradually in3months, and their deformation would be in low speed creep stage in6months. Rock mass’s maximum deformation of the left bank slope would develop gradually in superficial slope, which located at prospecting line IX to X2and downstream faults F14. Faults F14have obviously restraint effects on deformation of rock mass and shear zones. Deformation of the right bank slope would develop gradually along the shear zones C3and C3-1from outside to inside. Maximum deformation of the right bank slope would locate at exposed shear zones C3and C3-1upstream faults F20. Under reservoir operation conditions, stress and deformation of the spandrel groove slope would adjust gradually, and would be in stable gradually in6months. Maximum deformation of the left spandrel groove slope would locate at the arch dam top,834meters elevation. Maximum deformation of the right spandrel groove slope would locate at680meters elevation.更多还原