西藏怒江松塔水電站壩址區(qū)中緩傾角裂隙成因機(jī)制分析
發(fā)布時間：2018-12-19 20:43
【摘要】：中緩傾角裂隙是峽谷岸坡巖體中常見的一種結(jié)構(gòu)面，在許多水電工程中均有揭露。這種裂隙若充分發(fā)育，在有側(cè)向結(jié)構(gòu)面存在的情況下，可共同構(gòu)成巖體的控制控制性邊界，進(jìn)而影響壩址區(qū)高邊坡穩(wěn)定性和壩肩巖體抗滑穩(wěn)定性。所以弄清壩址區(qū)中緩傾角裂隙成因機(jī)制就顯得尤為重要。 本文以西藏怒江松塔水電站壩址區(qū)巖體為研究對象，在充分了解國內(nèi)外研究現(xiàn)狀的基礎(chǔ)上，通過現(xiàn)場勘查和室內(nèi)資料整理工作，分析研究了壩址區(qū)中緩傾角裂隙發(fā)育特征以及工程地質(zhì)特征；進(jìn)而通過對中緩傾角裂隙典型現(xiàn)象描述，將壩址區(qū)中緩傾角裂隙進(jìn)行分類，并針對每種裂隙分析其成因機(jī)制；最后通過采用應(yīng)變軟化模型和蠕變模型對怒江河谷進(jìn)行分階段下切模擬，分析了中緩傾角成因機(jī)制和間隔分布現(xiàn)象。具體研究內(nèi)容及成果如下： （1）中緩傾角裂隙總體特征研究 1、松塔壩址區(qū)中緩傾角裂隙右岸以NNE-NEE傾SE為主，左岸以NNE-NEE傾NW為主，呈倒“八”字分布在河谷兩岸�？傮w呈上陡下緩。 2、中緩裂從坡表到山體內(nèi)部的分布可明顯分為多裂隙段和少裂隙段（原巖段），其中在多裂隙段中緩裂也呈間隔分布。 3、中緩傾角在平硐內(nèi)一般延伸長度在10m以內(nèi)，其中又以1～3m裂隙居多。計算得到各平硐連通率基本在30～60%之間，說明中緩傾裂隙尚未構(gòu)成底滑面，仍處于表生改造階段。 4、通過對中緩裂工程性狀分析，可知壩址區(qū)大部分中緩裂為性狀較好的硬性結(jié)構(gòu)面。 （2）中緩傾角裂隙成因機(jī)制分析 1、原生型中緩傾有兩種：1）巖脈侵入基巖時的隱節(jié)理在后期河谷下切中顯現(xiàn)；2）花崗巖冷卻過程中形成的席狀裂隙。 2、構(gòu)造型中緩裂有兩種：1）可能因巖漿活動引發(fā)的低角度正斷緩裂；2）由里德爾切變效應(yīng)產(chǎn)生的與陡裂伴生的中緩裂。 3、表生型中緩裂有三種：1）差異卸荷回彈產(chǎn)生的近水平剪切裂隙；2）谷底水平應(yīng)力集中產(chǎn)生的壓剪裂隙；3）岸坡側(cè)向卸荷形成的張性、張剪性裂隙。 （3）中緩傾角裂隙成因數(shù)值模擬 通過數(shù)值軟件，采用分區(qū)破裂化理論和蠕變理論，利用應(yīng)變軟化模型和黏彈塑性蠕變模型，根據(jù)怒江河谷演化歷史，對其進(jìn)行分期次下切模擬，驗證了河谷在下切過程中，岸坡應(yīng)力場重分布，岸坡表部出現(xiàn)壓制拉裂區(qū)和谷底坡腳的剪應(yīng)力集中區(qū)，是表生型中緩傾角裂隙的主要成因。另外通過觀測剪應(yīng)變增量在不同下切階段隨水平方向的遷移，基本解釋了壩址區(qū)中緩裂間隔分布現(xiàn)象。
[Abstract]:The moderate dip angle fissure is a common structural plane in the slope rock mass of canyons, which has been exposed in many hydropower projects. If this kind of fissure is fully developed, the controlling boundary of rock mass can be formed together under the condition of the existence of lateral structural plane, which will affect the stability of high slope and anti-slide stability of abutment rock mass in the dam site area. So it is very important to make clear the formation mechanism of slow dip crack in dam site. This paper takes the rock mass in the dam area of Songta Hydropower Station of Nujiang River in Tibet as the research object, and on the basis of fully understanding the present research situation at home and abroad, through on-the-spot investigation and indoor data sorting work, The development characteristics and engineering geological characteristics of moderate dip fractures in dam site area are analyzed and studied. Then by describing the typical phenomena of moderate and gentle dip fractures, the fractures in the dam site are classified, and the genetic mechanism of each kind of fractures is analyzed. Finally, by using strain softening model and creep model, the formation mechanism of moderate dip angle and the phenomenon of interval distribution are analyzed. The specific research contents and results are as follows: (1) study on the general characteristics of moderate dip angle fissures. 1. In the Songta dam area, the NNE-NEE tilting SE is dominant on the right bank and the NNE-NEE tilting NW is the main one on the left bank. The word "eight" is distributed on both sides of the river valley. The overall appearance is steep and slow down. 2. The distribution from slope surface to mountain body can be obviously divided into multiple fissures section and little fissure section (original rock segment), in which the distribution of slow crack is also spaced in multi-fissured segment. (3) the average extension length of moderate dip angle is less than 10 m in the adit, in which 1 m crack is the most. The calculation shows that the connectivity rate of each adit is between 30 and 60%, which shows that the moderate slant fissure has not yet formed the bottom slip surface, and is still in the stage of supergene transformation. 4. Through the analysis of the middle slow cracking engineering characters, it can be seen that most of the middle slow cracks in the dam site are hard structural planes with good properties. (2) the genetic mechanism of moderate and gentle dip fractures 1. There are two types of primary gentle dip fractures: 1) the cryptic joints of the vein intruding into the bedrock appear in the later valley, 2) the sheet fractures formed during the granite cooling process. 2. There are two types of slow fracture in the tectonic type: 1) low angle positive fault induced by magmatic activity, 2) moderate slow fracture associated with steep fracture caused by the Rydell shear effect. 3. There are three types of slow fracture in the epigenetic type: 1) the near horizontal shear fissure caused by differential unloading springback; 2) the compressive shear crack caused by horizontal stress concentration at the bottom of the valley; 3) the tensional and tensional fracture formed by lateral unloading on the bank slope. (3) numerical simulation of the causes of moderate and slow dip fractures by numerical software, using the theory of zonal fracture and creep, using strain softening model and viscoelastic-plastic creep model, according to the evolution history of Nujiang River valley, It is verified that the redistribution of slope stress field in the process of down-cutting and the shear stress concentration area in the face of bank slope are the main causes of the moderate dip fractures in the supergene type by stages of down-cutting simulation on the slope surface and the shear stress concentration area at the foot of the bottom slope of the valley slope. The results show that the stress field of the slope is redistributed during the down-cutting process of the valley. In addition, the phenomenon of slow crack interval distribution in dam site is explained by observing the migration of shear strain increment with horizontal direction in different lower shear stages.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TV221.2
本文編號：2387425
[Abstract]:The moderate dip angle fissure is a common structural plane in the slope rock mass of canyons, which has been exposed in many hydropower projects. If this kind of fissure is fully developed, the controlling boundary of rock mass can be formed together under the condition of the existence of lateral structural plane, which will affect the stability of high slope and anti-slide stability of abutment rock mass in the dam site area. So it is very important to make clear the formation mechanism of slow dip crack in dam site. This paper takes the rock mass in the dam area of Songta Hydropower Station of Nujiang River in Tibet as the research object, and on the basis of fully understanding the present research situation at home and abroad, through on-the-spot investigation and indoor data sorting work, The development characteristics and engineering geological characteristics of moderate dip fractures in dam site area are analyzed and studied. Then by describing the typical phenomena of moderate and gentle dip fractures, the fractures in the dam site are classified, and the genetic mechanism of each kind of fractures is analyzed. Finally, by using strain softening model and creep model, the formation mechanism of moderate dip angle and the phenomenon of interval distribution are analyzed. The specific research contents and results are as follows: (1) study on the general characteristics of moderate dip angle fissures. 1. In the Songta dam area, the NNE-NEE tilting SE is dominant on the right bank and the NNE-NEE tilting NW is the main one on the left bank. The word "eight" is distributed on both sides of the river valley. The overall appearance is steep and slow down. 2. The distribution from slope surface to mountain body can be obviously divided into multiple fissures section and little fissure section (original rock segment), in which the distribution of slow crack is also spaced in multi-fissured segment. (3) the average extension length of moderate dip angle is less than 10 m in the adit, in which 1 m crack is the most. The calculation shows that the connectivity rate of each adit is between 30 and 60%, which shows that the moderate slant fissure has not yet formed the bottom slip surface, and is still in the stage of supergene transformation. 4. Through the analysis of the middle slow cracking engineering characters, it can be seen that most of the middle slow cracks in the dam site are hard structural planes with good properties. (2) the genetic mechanism of moderate and gentle dip fractures 1. There are two types of primary gentle dip fractures: 1) the cryptic joints of the vein intruding into the bedrock appear in the later valley, 2) the sheet fractures formed during the granite cooling process. 2. There are two types of slow fracture in the tectonic type: 1) low angle positive fault induced by magmatic activity, 2) moderate slow fracture associated with steep fracture caused by the Rydell shear effect. 3. There are three types of slow fracture in the epigenetic type: 1) the near horizontal shear fissure caused by differential unloading springback; 2) the compressive shear crack caused by horizontal stress concentration at the bottom of the valley; 3) the tensional and tensional fracture formed by lateral unloading on the bank slope. (3) numerical simulation of the causes of moderate and slow dip fractures by numerical software, using the theory of zonal fracture and creep, using strain softening model and viscoelastic-plastic creep model, according to the evolution history of Nujiang River valley, It is verified that the redistribution of slope stress field in the process of down-cutting and the shear stress concentration area in the face of bank slope are the main causes of the moderate dip fractures in the supergene type by stages of down-cutting simulation on the slope surface and the shear stress concentration area at the foot of the bottom slope of the valley slope. The results show that the stress field of the slope is redistributed during the down-cutting process of the valley. In addition, the phenomenon of slow crack interval distribution in dam site is explained by observing the migration of shear strain increment with horizontal direction in different lower shear stages.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TV221.2
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