【正文】 y軸對(duì)稱；水平位移也隨之增大，但是豎向位移并沒(méi)有明顯變化；其中最大位移出現(xiàn)在頂部。最大應(yīng)力出現(xiàn)在兩側(cè)，隨著尺寸的增加，兩側(cè)由拉應(yīng)力變?yōu)閴簯?yīng)力。③非連續(xù)結(jié)構(gòu)面角度對(duì)巷道穩(wěn)定性的影響當(dāng)發(fā)連續(xù)結(jié)構(gòu)的角度增加時(shí)，對(duì)于巷道位移分布和應(yīng)力分布區(qū)域有顯著的影響，其中最大位移位置會(huì)隨著角度的變化而變化，最大應(yīng)力分布位置始終在巷道的底部。當(dāng)角度由0176。增加到90176。時(shí)位移和應(yīng)力隨之增加，當(dāng)角度繼續(xù)增加到180176。，位移和應(yīng)力反而減小。④巖石性質(zhì)變化非連續(xù)結(jié)構(gòu)面對(duì)巷道穩(wěn)定性的影響 當(dāng)巖性發(fā)生改變時(shí)，應(yīng)力和位移分布區(qū)域并沒(méi)有明顯的變化，但是五種巖性中，砂巖和石英巖最為穩(wěn)定。白云巖和強(qiáng)風(fēng)化碳質(zhì)巖穩(wěn)定性不好?；?guī)r處于四者之間。⑤斷面間摩擦系數(shù)變化對(duì)圍巖穩(wěn)定性的影響 隨著摩擦系數(shù)的變化，應(yīng)力位移分布區(qū)域并沒(méi)有明顯變化，但是隨著摩擦系數(shù)的增加，巷道上的應(yīng)力隨著減小，水平位移也隨之減小，只有豎向位移隨之增大。①裂隙位置對(duì)巷道圍巖穩(wěn)定性的影響隨著裂隙所處徑向夾角的增加，巷道整體的應(yīng)力分布并沒(méi)有明顯的變化。巷道頂部和底部存在最大的水平應(yīng)力。巷道的兩側(cè)存在最大的豎向應(yīng)力。隨著角度增加，裂紋尖端的水平應(yīng)力是增長(zhǎng)趨勢(shì)；裂紋尖端的豎向應(yīng)力整體是減小的趨勢(shì)。②裂隙方位對(duì)巷道圍巖穩(wěn)定性的影響無(wú)論裂隙處于什么位置，由于裂隙和巷道的尺寸比較起來(lái)太小，所以對(duì)巷道的應(yīng)力位移分布區(qū)域沒(méi)有明顯的影響。但是對(duì)于處于拱腳的裂隙，要注意當(dāng)裂隙為90176。時(shí)的情況。這時(shí)豎向應(yīng)力較大，容易發(fā)生錯(cuò)動(dòng)。當(dāng)裂隙處于45176。時(shí)，應(yīng)注意裂隙為15176。和75176。兩種情況，這時(shí)，水平應(yīng)力和豎向應(yīng)力都偏大，容易產(chǎn)生破壞。參考文獻(xiàn)[1] 袁亮，低透氣煤層群無(wú)煤柱煤與瓦斯共采理論與實(shí)踐[M].北京：煤炭工業(yè)出版社，2008[2] 趙玉成，循環(huán)載荷作用下煤的力學(xué)性質(zhì)及聲發(fā)射特征演化規(guī)律，煤，2013(165) 15[3] 張里程，巷道圍巖穩(wěn)定性分析研究的現(xiàn)狀與存在問(wèn)題. 徐州工程學(xué)報(bào)，,33[4] 薛　琳，直墻拱形隧道圍巖粘彈性位移解析解. 巖土工程學(xué)報(bào),1996(5) ：96～101[5] 朱大勇,錢七虎,周早生復(fù)雜形狀硐室圍巖應(yīng)力彈性解析分析. 巖石力學(xué)與工程學(xué)報(bào)， 1999(4) :402～404 [6] 張路青,楊志法,呂愛鐘. 兩平行的任意形狀硐室圍巖位移場(chǎng)解析法研究及其在位移反分析中的應(yīng)用. 巖石力學(xué)與工程學(xué)報(bào),2000(3) :584～589[7] 朱素平,周楚良. 地下圓形隧道圍巖穩(wěn)定性的粘彈性力學(xué)分析. 同濟(jì)大學(xué)學(xué)報(bào),1994(9) :229～233[8] 朱素平,周楚良. 地下圓形隧道圍巖穩(wěn)定性的粘彈性力學(xué)分析. 同濟(jì)大學(xué)學(xué)報(bào),1994(9) :229～233[9] 程　樺,孫　鈞. 軟弱圍巖復(fù)合式隧道襯砌力學(xué)機(jī)理非線性大變形數(shù)值分析. 巖石力學(xué)與工程學(xué)報(bào),1997(4) :327～336[10] 譚云亮,王泳嘉. 巷道圍巖塑性狀態(tài)判定分析方法. 工程地質(zhì)學(xué)報(bào), 1996(2) :63～68[11] Shi GH,Goodman RE. 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This may significantly increase the risk of tunnel instability during excavation. In order to assess the stability of the diversion tunnels laboratory tests were carried out in association with the petrophysical properties, mechanical behaviors and waterweakening properties of chlorite schist. The continuous deformation of surrounding rock mass, the destruction of the support structure and a largescale collapse induced by the weak chlorite schist and high in situ stress were analyzed. The distributions of pressive deformation in the excavation zone with large deformations were also studied. In this regard, two reinforcement schemes for the excavation of diversion tunnel bottom section were proposed accordingly. This study could offer theoretical basis for deep tunnel construction in similar geological conditions.KeywordsDeep tunnel。Soft rock。Waterweakening effect。Large deformation。Stability1. IntroductionThe West ends of diversion (high pressure) tunnels 1 and 2 of Jinping II hydropower station were located in the chlorite schist stratum with the length of about 400m. This stratum is characterized with plex geological conditions, . high in situ stress, and large overburden depth. The main characteristics of chlorite schist are related to the weakness in the mechanical properties, waterweakening effects and significant creep strain of rocks. Extremely large deformation was observed during construction due to the inadequate support measures, such as delayed support and lowstrength support, after excavating the top section of tunnels. The significant interference of primary support with original lining section contributed to the continuously increasing deformation of rocks. This considerably increases the risk of instability of surrounding rock mass when excavating the bottom section of tunnels, resulting to a problem in the power generation capacity due to reduction of the tunnel crosssection.Many definitions and/or concepts regarding soft rocks have been proposed (Fan, 1995,Guo, 1996andLin, 1999). According to the work ofSciotti (1990), soft rocks, . sandstone (Nickmann etal., 2006) and mudstone (Yoshinaka etal., 1997), have the main characteristics such as large deformability, strong dependence of resistance on degree of saturation or temperature, and susceptibility to alteration. For simplicity, soft rocks have been classified into two sets (Clerici, 1992andRusso, 1994): geological soft rock and engineering soft rock. The set of the geological soft rock has the intrinsic properties of weakness, looseness and expansibility, while the engineering soft rock generates significant plastic strain and creep strain subjected to engineered effect. The chlorite schist of Jinping II hydropower station can be viewed as a geological soft rock due to its weakness in mechanical properties, but also as the engineering soft rock due to high in situ stress at depth of approximately 1500m.Excavating tunnel in soft rock stratum usually will cause accident due to the plex geological conditions and mechanical behaviors of soft rocks. Many methods of support techniques have been proposed consequently. For example, the New Austrian Tunneling Method (NATM) (Han, 1987) which is also known as sequential excavation method (SEM) is a popular method in modern tunnel design and (1970)studied the support system in terms of ene