【摘要】：巖石在其成巖及后期次生演化過(guò)程中，形成了諸如層理、片理、節(jié)理及斷層等原生或次生結(jié)構(gòu)面，正是由于這些成巖缺陷和構(gòu)造損傷的存在，使得巖石或巖體呈現(xiàn)明顯的各向異性特征。石英云母片巖具有片狀構(gòu)造，它所表現(xiàn)出的力學(xué)各向異性特征主要受控于巖石的礦物組成和排列組合方式，此特征對(duì)地下洞室穩(wěn)定性具有顯著影響。本文以丹巴水電站石英云母片巖為研究對(duì)象，通過(guò)微觀(guān)結(jié)構(gòu)及宏觀(guān)物理力學(xué)特性試驗(yàn)，并結(jié)合大量的現(xiàn)場(chǎng)調(diào)查和分析，以工程地質(zhì)分析評(píng)價(jià)為主線(xiàn)，運(yùn)用構(gòu)造地質(zhì)學(xué)、礦物巖石學(xué)、巖體力學(xué)、斷裂力學(xué)、各向異性理論等多種理論方法，準(zhǔn)確地把握了石英云母片巖的各向異性及其對(duì)圍巖穩(wěn)定性的影響。通過(guò)上述研究本文主要取得以下成果： （1）現(xiàn)場(chǎng)地質(zhì)調(diào)查表明：研究區(qū)在印支、燕山和喜山期經(jīng)歷了多期次變質(zhì)活動(dòng)的疊加改造，構(gòu)造作用極為復(fù)雜，區(qū)內(nèi)以剝蝕中-高山地貌為主，最大地應(yīng)力近水平且其值處于中等偏高級(jí)應(yīng)力量級(jí)，地下水不發(fā)育且以具一定的埋深基巖裂隙水為主。CPD1平洞圍巖（石英云母片巖）片理密集發(fā)育，強(qiáng)度較低，為軟質(zhì)巖，平洞自開(kāi)挖至今未支護(hù)，整體穩(wěn)定性較好。 （2）通過(guò)鑄體磨片試驗(yàn)和掃描電鏡試驗(yàn)對(duì)石英云母片巖礦物組成及微觀(guān)結(jié)構(gòu)進(jìn)行研究，揭示了石英云母片巖呈現(xiàn)各向異性的微觀(guān)機(jī)理。首先，通過(guò)對(duì)CPD1平洞42組磨片試驗(yàn)統(tǒng)計(jì)分析可得，平洞圍巖礦物以片狀云母、粒狀石英為主，礦物組成隨洞深呈現(xiàn)規(guī)律性變化。其次，采用電鏡掃描對(duì)石英云母片巖進(jìn)行鑒測(cè)表明，片狀和粒狀礦物呈現(xiàn)定向排列，且晶粒間或其內(nèi)部存在晶粒邊界、晶格斷裂、微裂隙等多種定向性微弱面。最后，結(jié)合地質(zhì)成因分析可知，石英云母片巖組構(gòu)單元經(jīng)歷了漫長(zhǎng)的地質(zhì)年代，這使得其內(nèi)部礦物顆粒及微弱面具有礦物晶格和形狀優(yōu)勢(shì)取向，從而使得石英云母片巖從宏觀(guān)和微觀(guān)均呈現(xiàn)出各向異性的特征。 （3）結(jié)合巖體各向異性理論，并采用單軸抗壓強(qiáng)度試驗(yàn)、三軸卸載試驗(yàn)、原位直剪試驗(yàn)及現(xiàn)場(chǎng)聲波測(cè)試對(duì)石英云母片巖宏觀(guān)物理力學(xué)各向異性進(jìn)行研究。單軸壓縮試驗(yàn)表明：隨著β值的增大，石英云母片巖的單軸抗壓強(qiáng)度與彈性模量均有先減少后增大的趨勢(shì)，呈“U”型，約在β=30°時(shí)，兩者均達(dá)到最小值；試樣的破壞模式主要為張拉破壞，并且破壞特征受控于片理與加載方向。三軸卸荷試驗(yàn)結(jié)果表明：石英云母片巖在卸荷作用下其強(qiáng)度及變形均存在各向異性特性，且隨著圍壓的增大石英云母片巖各向異性逐漸減弱；巖樣破壞模式均為穿層剪切破壞。現(xiàn)場(chǎng)聲波測(cè)試表明：石英云母片巖波速具有各向異性特征，沿順片理方向波速最高，沿垂直片理方向波速最低，其他方向的波速介于此兩者之間；巖樣從上部到下部波速明顯增高，且各向異性指數(shù)呈逐漸減少的趨勢(shì)�，F(xiàn)場(chǎng)巖石直剪試驗(yàn)表明：石英云母片巖剪切參數(shù)及巖樣變形特征均具有顯著的各向異性；平行片理的抗剪斷峰值強(qiáng)度參數(shù)f=0.61，C=0.84MPa，抗剪強(qiáng)度參數(shù)f′=0.45，C′=0.30MPa，試樣幾乎都有切層破壞現(xiàn)象；垂直片理的抗剪斷峰值強(qiáng)度參數(shù)f=0.76，C=2.75MPa，抗剪強(qiáng)度參數(shù)f′=0.69，C′=0.23MPa，試樣大多數(shù)剪切面都有1~3cm的起伏。 （4）通過(guò)現(xiàn)場(chǎng)地質(zhì)調(diào)查收集CPD1平洞相關(guān)地質(zhì)資料，并基于斷裂力學(xué)理論從微觀(guān)和宏觀(guān)角度對(duì)圍巖穩(wěn)定性的影響因素進(jìn)行分析。從微觀(guān)角度來(lái)說(shuō)，石英云母片巖的礦物組成對(duì)圍巖穩(wěn)定性具有較明顯的影響，對(duì)于圍巖石英礦物含量越高，圍巖力學(xué)性能越好，則圍巖穩(wěn)定性也就越好；除此平洞開(kāi)挖后沿片理方向上易產(chǎn)生應(yīng)力集中，該方向上的微裂紋易發(fā)生擴(kuò)展或產(chǎn)生沿顆粒間的滑移。從宏觀(guān)角度來(lái)說(shuō)，影響圍巖穩(wěn)定的因素可以分為地質(zhì)因素（巖體強(qiáng)度、巖體完整性、巖體結(jié)構(gòu)、地應(yīng)力、地下水等）和工程因素（開(kāi)挖方式方法、洞室形狀及尺寸等）。其中，巖體強(qiáng)度、地應(yīng)力及開(kāi)挖方式對(duì)圍巖穩(wěn)定性影響顯著，為平洞圍巖穩(wěn)定性控制性因素。 （5）通過(guò)現(xiàn)場(chǎng)地質(zhì)調(diào)查，結(jié)合大量室內(nèi)及現(xiàn)場(chǎng)試驗(yàn)數(shù)據(jù)統(tǒng)計(jì)分析。首先，作者認(rèn)為石英云母片巖的片理是一種特殊的結(jié)構(gòu)面，其各方面的性質(zhì)已經(jīng)在巖石縱波速度、巖石單軸飽和抗壓強(qiáng)度等參數(shù)中得到了比較充分的反映，故片理不應(yīng)與節(jié)理、斷層破碎帶等其他結(jié)構(gòu)面一起參與巖體參數(shù)的劃分或評(píng)定，并將平洞圍巖的巖體結(jié)構(gòu)類(lèi)型定名為“似塊狀結(jié)構(gòu)”；其次，，以水電工程圍巖工程地質(zhì)分類(lèi)和圍巖初步分類(lèi)標(biāo)準(zhǔn)為基礎(chǔ)，針對(duì)高地應(yīng)力、巖體結(jié)構(gòu)及片理產(chǎn)狀進(jìn)行修正，建立丹巴水電站地下洞室圍巖初判標(biāo)準(zhǔn)；最后，根據(jù)圍巖工程地質(zhì)分類(lèi)以及實(shí)際圍巖類(lèi)別、巖體變形與圍巖類(lèi)別分類(lèi)標(biāo)準(zhǔn)，依據(jù)丹巴軟巖巖質(zhì)類(lèi)型、巖體結(jié)構(gòu)類(lèi)型和巖體完整程度，并結(jié)合現(xiàn)場(chǎng)地質(zhì)調(diào)查及監(jiān)測(cè)資料，建立了適合丹巴地下洞室的軟弱圍巖分類(lèi)體系—SRCS體系（Soft Rock Classification System）
[Abstract]:Primary or secondary structural planes such as bedding, schistosity, joints and faults are formed in the process of rock diagenesis and later secondary evolution. It is precisely because of these diagenetic defects and structural damage that the rock or rock mass exhibits obvious anisotropic characteristics. In this paper, the quartz mica schist of Danba Hydropower Station is taken as the research object, through the test of microstructure and macroscopic physical and mechanical properties, and combined with a large number of field investigation and analysis, the engineering geological analysis and evaluation are carried out. As the main line, the anisotropy of quartz-mica schist and its influence on the stability of surrounding rock are accurately grasped by many theoretical methods, such as tectonic geology, mineral petrology, rock mass mechanics, fracture mechanics and anisotropy theory.
(1) Field geological survey shows that the study area underwent multi-stage metamorphic superimposition in Indosinian, Yanshan and Himalayan periods, and the tectonic process was extremely complex. The area was dominated by denuded middle-alpine landforms, the maximum geostress was near the level and its value was in medium-to-high-grade stress magnitude, and the groundwater was undeveloped and the bedrock fissures with certain buried depth were found. The surrounding rock (quartz mica schist) of CPD1 flat cave is densely developed and has low strength. It is soft rock. The flat cave has not been supported since excavation, and the overall stability is good.
(2) The mineral composition and microstructure of quartz-mica schist were studied by casting grinding test and scanning electron microscope test, and the mechanism of anisotropy of quartz-mica schist was revealed. Firstly, through the statistical analysis of 42 groups of grinding test of CPD1 flat cave, it was found that the surrounding rock minerals of flat cave were mainly lamellar mica, granular quartz and mineral composition was mainly granular quartz. Secondly, the quartz-mica schist is characterized by directional alignment of schist and granular minerals, and there are grain boundaries, lattice fractures, micro-cracks and other orientational facets between or within the grains. Finally, combined with the analysis of geological genesis, the fabric unit of quartz-mica schist is known. After a long geological age, the mineral grains and faint faces in the quartz-mica schist have the predominant orientation of mineral lattice and shape, which makes the quartz-mica schist exhibit anisotropic characteristics both macroscopically and microscopically.
(3) The macroscopic physical and mechanical anisotropy of quartz-mica schist is studied by uniaxial compressive strength test, triaxial unloading test, in-situ direct shear test and in-situ acoustic wave test. Uniaxial compressive test shows that the uniaxial compressive strength and elastic modulus of quartz-mica schist increase with the value of beta. The results of triaxial unloading test show that the strength and deformation of quartz-mica schist are anisotropic under unloading, and the failure mode is mainly tensile failure, and the failure characteristics are controlled by the direction of sheeting and loading. With the increase of confining pressure, the anisotropy of quartz-mica schist gradually weakens, and the failure modes of rock samples are shear failure through layers. The in-situ direct shear tests show that the shear parameters and deformation characteristics of quartz-mica schist have significant anisotropy, and the peak shear strength parameters of parallel schist f = 0.61, C = 0.84MPa, shear strength parameters f'= 0.45, C'= 0.30MPa. The peak shear strength parameter f = 0.76, C = 2.75 MPa, shear strength parameter f'= 0.69, C'= 0.23 MPa, and most of the shear planes of the specimens fluctuate from 1 cm to 3 cm.
(4) Based on the fracture mechanics theory, the factors influencing the stability of surrounding rocks are analyzed from the micro and macro aspects. From the micro point of view, the mineral composition of quartz-mica schist has obvious influence on the stability of surrounding rocks. The higher the content of quartz minerals in surrounding rocks, the higher the content of quartz minerals in surrounding rocks. The better the mechanical properties of rock, the better the stability of surrounding rock; besides, the stress concentration along the cleavage direction is easy to occur after excavation of the flat tunnel, and the micro-cracks in this direction are easy to expand or slip along the grain. From a macroscopic point of view, the factors affecting the stability of surrounding rock can be divided into geological factors (rock strength, rock integrity, rock mass consolidation). Structure, in-situ stress, groundwater, etc.) and engineering factors (excavation method, cavern shape and size, etc.). Among them, rock mass strength, in-situ stress and excavation method have significant influence on the stability of surrounding rock, and are the controlling factors of the stability of surrounding rock of flat cavern.
(5) Through on-site geological survey and statistical analysis of a large number of laboratory and field test data, the author considers that the schistosity of quartz-mica schist is a special structural plane whose properties have been fully reflected in the parameters of P-wave velocity and uniaxial saturated compressive strength of rock, so schistosity should not be associated with joints. Other structural planes, such as fault fracture zones, participate in the division or evaluation of rock mass parameters, and name the rock mass structure type of the surrounding rock of Pingdong Tunnel as "block-like structure"; secondly, based on the engineering geological classification of surrounding rock of hydropower engineering and the preliminary classification standard of surrounding rock, the high geostress, rock mass structure and schistosity occurrence are modified and constructed. Initial criteria for surrounding rock of underground cavern of Lidanba Hydropower Station; Finally, according to engineering geological classification of surrounding rock, actual surrounding rock classification, rock mass deformation and classification criteria of surrounding rock, according to soft rock type, rock mass structure type and rock mass integrity of Danba Hydropower Station, combined with on-site geological survey and monitoring data, an underground cavern suitable for Danba Hydropower Station is established. Classification system of weak surrounding rock in the room -- SRCS system (Soft Rock Classification System)
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TU45

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