金沙江某水電站岸坡深部變形破裂成因分析
發(fā)布時(shí)間：2018-07-16 23:50
【摘要】：金沙江某水電站壩址區(qū)岸坡常規(guī)風(fēng)化卸荷帶以里的深部新鮮巖體內(nèi)發(fā)育有一系列的變形破裂現(xiàn)象，與西南地區(qū)其他水電站岸坡已揭露的深部裂縫現(xiàn)象存在明顯的差異，成為制約工程勘察、設(shè)計(jì)、施工和運(yùn)營(yíng)的重大工程地質(zhì)問(wèn)題。研究壩址區(qū)深部變形破裂的基本特征、揭示其成因機(jī)制，具有十分重要的理論價(jià)值和現(xiàn)實(shí)意義。 本文以壩址區(qū)岸坡深部變形破裂為研究對(duì)象，在查明深部變形破裂所處的地質(zhì)環(huán)境背景及河谷演化模式的基礎(chǔ)上，結(jié)合現(xiàn)場(chǎng)的地應(yīng)力實(shí)測(cè)資料，通過(guò)對(duì)河谷應(yīng)力場(chǎng)進(jìn)行三維數(shù)值模擬反演，研究壩址區(qū)河谷應(yīng)力場(chǎng)的演化特征，探討深部變形破裂形成演化的宏觀地應(yīng)力背景。忠實(shí)于地質(zhì)原型，詳細(xì)分析深部變形破裂的現(xiàn)場(chǎng)地質(zhì)描述，提取共性特征，進(jìn)而將深部變形破裂分為三類�？偨Y(jié)歸納深部變形破裂的發(fā)育分布規(guī)律和變形破壞特征，建立深部變形破裂的地質(zhì)力學(xué)“概念模型”。在此基礎(chǔ)上，以淺生時(shí)效改造理論為基礎(chǔ)，采用地質(zhì)過(guò)程機(jī)制分析方法，結(jié)合巖石力學(xué)、構(gòu)造地質(zhì)學(xué)等知識(shí)，初步揭示深部變形破裂的成因機(jī)制。本文主要取得的研究成果如下： （1）深入分析歸納深部變形破裂的地質(zhì)描述，提取表觀特征間的共性，將壩址區(qū)出露的深部變形破裂分為三類：微張型、中度松弛型和強(qiáng)烈松弛型。 （2）岸坡淺表部巖體在左岸傾NW向結(jié)構(gòu)面發(fā)育，右岸傾SE向結(jié)構(gòu)面發(fā)育，且均以中等傾角產(chǎn)出。岸坡淺表部結(jié)構(gòu)面發(fā)育受河谷下切側(cè)向卸荷回彈作用明顯，平行于岸坡傾向坡外的結(jié)構(gòu)面發(fā)育，結(jié)構(gòu)面傾角與坡面傾角基本一致。深部巖體結(jié)構(gòu)面除了具備淺部巖體結(jié)構(gòu)面特征外，還發(fā)育有NE/NW和NE/SE向陡傾角結(jié)構(gòu)面，形成一對(duì)陡傾角的共軛結(jié)構(gòu)面體系。 （3）深部變形破裂除PD29、PD01、PD10均有出露�？傮w上高程越大，深部變形破裂發(fā)育程度越高。微張型深部變形破裂在左岸出露的平硐較右岸多，但兩岸發(fā)育的數(shù)量相差不大，兩岸發(fā)育數(shù)量隨高程增高而增加。中度松弛型深部變形破裂在左岸10個(gè)平硐出露，在右岸只在2個(gè)平硐中出露，左岸總共68條，右岸發(fā)育10條，中高程最多，高程程最少。強(qiáng)烈松弛型深部變形破裂左岸在3個(gè)平硐內(nèi)出露，發(fā)育20條；右岸在7個(gè)平硐中出露，發(fā)育48條，總體發(fā)育在高高程，低、中高程發(fā)育較少。兩岸深部變形破裂集中發(fā)育的空間位置大致相同，主要集中在水平深度60-150m、垂直深度60-180m的空間范圍內(nèi)。 （4）兩岸深部變形破裂總體上為NNE/NW方向，其中一組為中等傾角，另一組為陡傾角。其中，左岸優(yōu)勢(shì)方向?yàn)镹NE/NW，大致與坡面平行，一組為中等傾角，另一組為陡傾角，83°傾角最為發(fā)育。右岸優(yōu)勢(shì)方向在NS/E~NNE/SE之間，以中陡傾角為主，大致平行與坡面。 （5）根據(jù)深部變形破裂的基本特征建立每類深部變形破裂的概念模型，結(jié)合壩址區(qū)的地應(yīng)力演化特征，初步推斷深部變形破裂形成的宏觀機(jī)制為： 在NEE向最大主應(yīng)力以及河谷下切岸坡巖體卸荷回彈變形的共同作用下，岸坡巖體能量劇烈釋放，當(dāng)釋放的能量高于岸坡深部巖體中發(fā)育的NE向的兩組共軛節(jié)理裂隙的強(qiáng)度時(shí)，節(jié)理裂隙賦存的深部微新巖體在近于軸向壓力的作用下，發(fā)生繼承性的張性破裂，，破裂面優(yōu)勢(shì)方向在最大主應(yīng)力和河谷走向之間，共軛節(jié)理在兩岸分別發(fā)育傾坡外的一組（左岸NE/NW發(fā)育，右岸NE/SE發(fā)育），其中： ①微張型：深部巖體在張破裂形成后，由于壩址區(qū)岸坡為山脊-沖溝相間地貌，而沖溝具有匯水的作用，匯聚的地表水沿著節(jié)理利裂隙深入坡體內(nèi)。位于沖溝下方坡體內(nèi)的深部變形破裂最易遭受下滲的地下水的風(fēng)化侵蝕，故巖體風(fēng)化銹染程度較大。分析表明，微張型深部變形破裂均位于沖溝下方的破體內(nèi)。 根據(jù)格里菲斯裂紋擴(kuò)展準(zhǔn)則，坡體內(nèi)NEE向的結(jié)構(gòu)面與最大主應(yīng)力方向近于平行或夾角很小，遠(yuǎn)小于裂紋的破裂角，故NEE向的結(jié)構(gòu)面并不處于最有利于裂紋擴(kuò)展的環(huán)境，所以微張型深部變形破裂的張開(kāi)寬度很小。 ②中度松弛性：對(duì)于與最大主應(yīng)力方向斜交的NE向節(jié)理裂隙，除了受到壓致張破裂外，由于局部應(yīng)力場(chǎng)及微地貌臨空卸荷條件的差異，還會(huì)發(fā)生相對(duì)錯(cuò)動(dòng)，產(chǎn)生剪切破壞。對(duì)于閉合較緊密或充填較密實(shí)巖塊的結(jié)構(gòu)面，充填的花崗巖巖塊在剪切作用下破碎成“砂糖狀”花崗巖巖屑，形成中度松弛型深部變形破裂。 根據(jù)格里菲斯裂紋擴(kuò)展準(zhǔn)則，坡體內(nèi)NNE向的結(jié)構(gòu)面以及四條僅EW向小斷層與最大主應(yīng)力方向夾角在30°左右，近似等于裂紋的破裂角，故NNE向的結(jié)構(gòu)面處于最有利于裂紋擴(kuò)展的方向，所以中度松弛型的張開(kāi)寬度比微張型大。 ③強(qiáng)烈松弛型：斷層或長(zhǎng)達(dá)結(jié)構(gòu)面附近巖體變形破壞程度更高，巖體塊裂、碎裂化，結(jié)構(gòu)面充填物松散，甚至局部架空，結(jié)構(gòu)面受到擠壓發(fā)生張性破壞后充填物大部分脫落，在剪切作用下結(jié)構(gòu)面附近巖體進(jìn)一步破壞脫落，形成強(qiáng)烈松弛型深部變形破裂。右岸高高程PD44、PD24所處的卸荷拉裂體最為發(fā)育。 （6）岸坡深部變形破裂是在河谷地貌形成演化過(guò)程中，伴隨區(qū)域性剝蝕和河谷下切過(guò)程，岸坡構(gòu)造應(yīng)力場(chǎng)向自重應(yīng)力場(chǎng)轉(zhuǎn)化，深部節(jié)理裂隙優(yōu)勢(shì)方向與最大主應(yīng)力以一定角度斜交時(shí)，在張剪應(yīng)力環(huán)境下，產(chǎn)生的不同破壞程度的繼生性的變形破裂。
[Abstract]:There are a series of deformation and rupture phenomena in the deep fresh rock mass in the slope of the dam site of a hydropower station in Jinsha River . There is a significant difference between the deep fractures exposed to the bank slope of other hydropower stations in Southwest China . It is a major engineering geological problem that restricts the investigation , design , construction and operation of the project . The basic characteristics of deep deformation and rupture in the dam site area are studied , the cause mechanism is revealed , and the important theoretical value and practical significance are disclosed .
Based on the analysis of the geological environment background and the river valley evolution model in the dam site area , based on the investigation of the geological environment background and the valley evolution model in the deep deformation fracture , the authors study the evolution characteristics of the stress field in the river valley area and discuss the macroscopic geostress background of the evolution of deep deformation rupture .
( 1 ) In - depth analysis of the geological description of deep deformation fracture , and extracting the commonness between apparent features , the deep deformation and rupture of the exposed deep deformation in the dam site area are divided into three types : microtension type , moderate relaxation type and intensive relaxation type .
( 2 ) The rock mass on the bank slope is developed on the left bank from the NW to the structural plane , and the right bank slope SE is developed on the structural plane . The structure surface developed by the lower cut side of the bank slope is obviously developed , and the inclination of the structural plane is basically the same as that of the slope surface .
( 3 ) Except PD29 , PD01 and PD10 in deep deformation , the higher the overall elevation , the higher the fracture development degree of deep deformation .
On the right bank , there are 48 out of seven flat chambers , 48 are developed , the overall development is at high elevation , low and medium elevation is less . The spatial position of the development of deep deformation and rupture of both sides is about the same , and is mainly concentrated in the space range of 60 - 150 m and vertical depth of 60 - 180m .
( 4 ) The fracture of deep deformation on both sides of the two sides is in the direction of NE / NW , one of which is medium dip and the other is steep .
( 5 ) Based on the basic features of deep deformation fracture , a conceptual model of deep deformation rupture is established . Combined with the geostress evolution characteristics of the dam site area , the macroscopic mechanism of deep deformation rupture is preliminarily deduced .
Under the joint action of the maximum principal stress and the unloading rebound deformation of the lower slope rock mass in the valley , the energy of the rock mass in the bank slope is strongly released . When the released energy is higher than the strength of the NE - directional two groups of conjugate joints developed in the deep rock mass in the bank slope , the deep micro - new rock mass with joint fissure is fractured , the dominant direction of the fracture surface is between the maximum main stress and the valley direction , and the conjugate joint is developed on the left bank NE / NW development and the right bank NE / SE respectively .
The results show that the deep deformation breakdown in the lower slope of the gully is the most vulnerable to the weathering erosion of the underground water . The analysis indicates that the deep deformation and rupture of the rock mass are located in the broken body under the gully .
According to the Griffiths crack propagation criterion , the structural plane in the direction of the slope body and the maximum principal stress direction are close to the parallel or included angle so as to be far smaller than the crack angle of the crack , so the circumferential structural plane is not in the environment which is favorable for crack propagation , so that the opening width of the micro - tension deep deformation fracture is small .
( 2 ) moderate relaxation : for NE - joints with oblique intersection with the maximum principal stress direction , in addition to being subjected to compression - induced rupture , relative error can occur due to the difference between local stress field and micro - geomorphic near - air unloading condition , and shear failure is generated .
According to the Griffiths crack propagation criterion , the structural plane in the longitudinal direction of the slope and four EW - trending small faults and the maximum principal stress direction are approximately equal to or less than 30 degrees , which is approximately equal to the crack angle of the crack , so that the structural plane in the trending direction is in the direction which is favorable for crack propagation , so that the opening width of the moderate relaxation type is larger than that of the microtension type .
( 3 ) The strong relaxation type : the deformation degree of the rock mass near the fault or the length of the structural plane is higher , the mass of the rock mass is cracked , fragmented , the structural plane filling is loose , and even the local overhead , the structural plane is subjected to the compressive deformation and the filling material mostly falls off , and the rock mass in the vicinity of the structural surface is further damaged and falls off under the shearing action , thereby forming a strong relaxation type deep deformation rupture .
( 6 ) The deep deformation and rupture of the bank slope is accompanied by regional erosion and valley cutting , along with the regional erosion and the valley cutting process , the stress field of the bank slope tectonic stress field is transformed to the dead weight , and the dominant direction of the deep joint fissure and the maximum principal stress are inclined at a certain angle .
【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
【分類號(hào)】：TV223
[Abstract]:There are a series of deformation and rupture phenomena in the deep fresh rock mass in the slope of the dam site of a hydropower station in Jinsha River . There is a significant difference between the deep fractures exposed to the bank slope of other hydropower stations in Southwest China . It is a major engineering geological problem that restricts the investigation , design , construction and operation of the project . The basic characteristics of deep deformation and rupture in the dam site area are studied , the cause mechanism is revealed , and the important theoretical value and practical significance are disclosed .
Based on the analysis of the geological environment background and the river valley evolution model in the dam site area , based on the investigation of the geological environment background and the valley evolution model in the deep deformation fracture , the authors study the evolution characteristics of the stress field in the river valley area and discuss the macroscopic geostress background of the evolution of deep deformation rupture .
( 1 ) In - depth analysis of the geological description of deep deformation fracture , and extracting the commonness between apparent features , the deep deformation and rupture of the exposed deep deformation in the dam site area are divided into three types : microtension type , moderate relaxation type and intensive relaxation type .
( 2 ) The rock mass on the bank slope is developed on the left bank from the NW to the structural plane , and the right bank slope SE is developed on the structural plane . The structure surface developed by the lower cut side of the bank slope is obviously developed , and the inclination of the structural plane is basically the same as that of the slope surface .
( 3 ) Except PD29 , PD01 and PD10 in deep deformation , the higher the overall elevation , the higher the fracture development degree of deep deformation .
On the right bank , there are 48 out of seven flat chambers , 48 are developed , the overall development is at high elevation , low and medium elevation is less . The spatial position of the development of deep deformation and rupture of both sides is about the same , and is mainly concentrated in the space range of 60 - 150 m and vertical depth of 60 - 180m .
( 4 ) The fracture of deep deformation on both sides of the two sides is in the direction of NE / NW , one of which is medium dip and the other is steep .
( 5 ) Based on the basic features of deep deformation fracture , a conceptual model of deep deformation rupture is established . Combined with the geostress evolution characteristics of the dam site area , the macroscopic mechanism of deep deformation rupture is preliminarily deduced .
Under the joint action of the maximum principal stress and the unloading rebound deformation of the lower slope rock mass in the valley , the energy of the rock mass in the bank slope is strongly released . When the released energy is higher than the strength of the NE - directional two groups of conjugate joints developed in the deep rock mass in the bank slope , the deep micro - new rock mass with joint fissure is fractured , the dominant direction of the fracture surface is between the maximum main stress and the valley direction , and the conjugate joint is developed on the left bank NE / NW development and the right bank NE / SE respectively .
The results show that the deep deformation breakdown in the lower slope of the gully is the most vulnerable to the weathering erosion of the underground water . The analysis indicates that the deep deformation and rupture of the rock mass are located in the broken body under the gully .
According to the Griffiths crack propagation criterion , the structural plane in the direction of the slope body and the maximum principal stress direction are close to the parallel or included angle so as to be far smaller than the crack angle of the crack , so the circumferential structural plane is not in the environment which is favorable for crack propagation , so that the opening width of the micro - tension deep deformation fracture is small .
( 2 ) moderate relaxation : for NE - joints with oblique intersection with the maximum principal stress direction , in addition to being subjected to compression - induced rupture , relative error can occur due to the difference between local stress field and micro - geomorphic near - air unloading condition , and shear failure is generated .
According to the Griffiths crack propagation criterion , the structural plane in the longitudinal direction of the slope and four EW - trending small faults and the maximum principal stress direction are approximately equal to or less than 30 degrees , which is approximately equal to the crack angle of the crack , so that the structural plane in the trending direction is in the direction which is favorable for crack propagation , so that the opening width of the moderate relaxation type is larger than that of the microtension type .
( 3 ) The strong relaxation type : the deformation degree of the rock mass near the fault or the length of the structural plane is higher , the mass of the rock mass is cracked , fragmented , the structural plane filling is loose , and even the local overhead , the structural plane is subjected to the compressive deformation and the filling material mostly falls off , and the rock mass in the vicinity of the structural surface is further damaged and falls off under the shearing action , thereby forming a strong relaxation type deep deformation rupture .
( 6 ) The deep deformation and rupture of the bank slope is accompanied by regional erosion and valley cutting , along with the regional erosion and the valley cutting process , the stress field of the bank slope tectonic stress field is transformed to the dead weight , and the dominant direction of the deep joint fissure and the maximum principal stress are inclined at a certain angle .
【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
【分類號(hào)】：TV223
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