黑河水庫壩肩邊坡云母石英片巖三軸蠕變機(jī)理及蠕變模型研究

1、黑河水庫壩肩邊坡云母石英片巖三軸蠕變機(jī)理及蠕變模型研究        本文以黑河水庫左壩肩的云母石英片巖為研究對(duì)象，采用試驗(yàn)研究、理論分析相結(jié)合，宏、微觀研究相結(jié)合的研究方法，基于三軸蠕變?cè)囼?yàn)結(jié)果，電子顯微鏡和偏光顯微鏡掃描測(cè)試結(jié)果，對(duì)云母石英片巖的蠕變特性、蠕變機(jī)理進(jìn)行了分析，并建立了云母石英片巖的蠕變模型，為邊坡變形破壞預(yù)測(cè)奠定理論基礎(chǔ)。首先，對(duì)片理發(fā)育的軟弱變質(zhì)巖云母石英片巖，在軸向力與片理垂直的條件下，采用巖石全自動(dòng)流變伺服儀進(jìn)行了三軸壓縮蠕變?cè)囼?yàn)，對(duì)軸向蠕變和徑向蠕變進(jìn)行了對(duì)比分析，提出徑向蠕變比軸向蠕變

2、敏感，以徑向蠕變長(zhǎng)期強(qiáng)度作為長(zhǎng)期強(qiáng)度更合理。研究了圍壓對(duì)云母石英片巖三軸蠕變的影響，進(jìn)一步指出圍壓越大，對(duì)徑向變形的約束能力越強(qiáng)，徑向蠕變長(zhǎng)期強(qiáng)度和軸向蠕變長(zhǎng)期強(qiáng)度均增加，徑向蠕變長(zhǎng)期強(qiáng)度與軸向蠕變長(zhǎng)期強(qiáng)度的比值減小。在單軸蠕變時(shí)，軸向蠕變長(zhǎng)期強(qiáng)度可以作為軟巖的長(zhǎng)期強(qiáng)度?？偨Y(jié)出軸向、徑向等時(shí)應(yīng)力應(yīng)變曲線的特點(diǎn)，表明云母石英片巖的蠕變具有明顯的非線形特征?？偨Y(jié)出三種類型的軸向、徑向蠕變速率時(shí)間曲線和對(duì)應(yīng)的三種類型粘滯系數(shù)時(shí)間關(guān)系曲線。指出現(xiàn)有的蠕變?cè)M合模型無法描述加速蠕變階段的根本原因是模型中的粘滯系數(shù)沒有反映出其實(shí)際變化規(guī)律。然后，通過偏光顯微鏡和電子顯微鏡測(cè)試不同蠕變階段云母石英片巖徑軸

3、向的微觀結(jié)構(gòu)變化，將云母石英片巖內(nèi)部分為空隙、裂隙等缺陷、堅(jiān)硬部分和軟弱部分共三部分，提出了張開裂隙的閉合、軟弱部分的位置調(diào)整、微破裂和堅(jiān)硬部分的位置調(diào)整四種微結(jié)構(gòu)變化，在此基礎(chǔ)上，探討了云母石英片巖的微觀蠕變機(jī)理，對(duì)衰減蠕變階段、等速蠕變階段和加速蠕變階段的微觀機(jī)理進(jìn)行了合理解釋，并將微觀結(jié)構(gòu)變化引起的效應(yīng)歸結(jié)為空隙率的變化和損傷效應(yīng)，通過建立空隙率、損傷變量和宏觀應(yīng)力、應(yīng)變的關(guān)系，間接地建立了宏觀力學(xué)變量和微觀結(jié)構(gòu)變化的關(guān)系。接著，建立了云母石英片巖的七元件線性粘彈塑性蠕變模型和非線性粘彈塑性蠕變模型，對(duì)軸向蠕變和徑向蠕變曲線采用同一模型分別進(jìn)行了擬合，確定了模型參數(shù)，根據(jù)試驗(yàn)曲線和擬合曲

4、線的吻合情況，驗(yàn)證了模型的正確性；用各模型參數(shù)的平均值作為代表值研究了圍壓對(duì)模型參數(shù)的影響，軸向和徑向模型參數(shù)的區(qū)別?？偨Y(jié)出由試驗(yàn)曲線擬合求模型參數(shù)過程中的影響因素，提出用參數(shù)綜合辯識(shí)法來進(jìn)行模型參數(shù)選擇。最后，定義了蠕變損傷變量，該蠕變損傷變量只有2個(gè)模型參數(shù)，能全面地反映蠕變過程中的四種微結(jié)構(gòu)變化和蠕變機(jī)理，簡(jiǎn)化分解后的蠕變損傷變量能描述在破壞應(yīng)力下和中高應(yīng)力下的粘滯系數(shù)_3和時(shí)間關(guān)系。采用全解耦合的方法來考慮云母石英片巖損傷和蠕變的耦合作用，得到了能反映蠕變機(jī)理的云母石英片巖蠕變損傷本構(gòu)方程，對(duì)模型進(jìn)行了驗(yàn)證，確定了模型參數(shù)，并進(jìn)行了參數(shù)敏感性分析In this paper, aimed

5、 at mica-quartzose schist at left dam abutment of heihe reservoir, by using the study method that test study combined with theoretical analysis, macro-scope study combined with micro-scope study, the creep characteristics and creep mechanism of mica-quartzose sschist are analyzed, the creep constitu

6、tion models are alse established on the basis of triaxial creep tests, polarization microscope analysis and scanning electron microscope analysis.Firstly, triaxial compression creep tests with mica-quartzose schist which is a kind of soft metamorphic rock with lots of schistosity surfaces were carri

7、ed out on the rock servo-controlling rheology testing machine under the condition of the axial stress vertical to the direction of the schistosity surface. Axial creep characteristics of mica-quartzose schist were analyzed by comparing with radial creep characteristics. It was proposed that, for the

8、 mica-quartzose schist, taking the long-term strength of radial creep as the long-term strength was more reasonable since the radial creep is more sensitive than the axial creep. Besides, the higher confining compression is, the stronger the restrain of compression was to radial deformation, which r

9、esulted in increase of both the long-term strength of radial creep and the long-term strength axial creep. However, the ratio of the long-term strength of radial creep to the long-term strength axial creep reduces with increased confining compression, therefore, the long-term strength of axial creep

10、 can be taken as the long-term strength when studying the uniaxial creep characteristics. The test results alse show that the schistosity surfaces have little influence on the creep characteristic of mica-quartzose schist and it can not control the creep of mica-quartzose. The characteristics of rad

11、ial isochrounous stress-strain curve and axial isochrounous stress-strain curve are concluded, which shows that the creep of mica-quartzose schist has apparent nonlinesrity. Three kinds of axial creep rate-time surves and radial creep rate-time curves with the related three kinds of viscous coeffici

12、ent-time curves have been summarized as well, furthermore, it proposes that the radical reasons of the component-combined creep model can not describe the speedup creep phase are that they can not reflect the true variation regularity of viscosity coefficient.Secondly, mica-quartzose schist is separ

13、ated as defaults such as pores and cracks, relative rigid part and relative rigid soft which are altogether three parts on the basis of polarization microscope analysis and scanning electron microscope analysis of both axial and radial strip of mica-quartzose schist at different creep stage, at the

14、same time, four kinds of microstructure change which are the close of open crack, the situation change of relative rigid part, the situation change of relative soft part and micro-cracking are put forward. Micro-creep mechanism of mica-quartzose schist is investigated, the reasonable interpretations

15、 of micro-mechanism on the initial attenuation creep phase , the stabilization creep phase and the speedup creep phase are put forward. The influence of microstructure change on mica-quartzose schist are summarized as the damage effect and the change of porosity, the relation between the macro-mecha

16、nics variable and microstructure change is established indirectly through establishing the relation of macro-stress and macro-strain with porosity and damage variable.Thirdly, seven-component linear viscoelastoplastic creep model and nonlinear viscoelastoplastic creep model of mica-quartzose schist

17、are established. By using a same model, the model parameters of axial creep and radial creep are fitted in accordance with test curves and the comparison between the test curves and fitted curves shows that the creep model is right and reasonable. The influence of compression to model parameters and

18、 the different between axial model parameters and radial model parameters are also studied by comparing the average of every model parameters. The factors which influence the model parameters during in the course of fitting are summarized, and a comprehensive identification method to select model parameters is put forward.Finally, a creep damage variable which has two model parameters and can reflect both the creep mechani