本文選題：卸荷破壞 + 能量　； 參考：《青島理工大學(xué)》2014年博士論文

【摘要】：本論文包含兩個(gè)部分：一是針對(duì)地下工程開挖的復(fù)雜加、卸荷過程，尤其是卸荷過程，弄清卸荷路徑下的巖石破壞機(jī)理，重點(diǎn)研究不同卸荷路徑下巖石宏細(xì)觀破壞機(jī)理，包括：不同卸荷條件破壞過程中能量演化規(guī)律；巖石卸荷破壞過程中聲發(fā)射特征演化規(guī)律與量化分析；基于顆粒流方法巖石卸荷破壞過程數(shù)值模擬等。二是針對(duì)巖石地鐵工程設(shè)計(jì)計(jì)算的實(shí)際問題，應(yīng)用數(shù)值極限分析方法，開展對(duì)巖石地鐵工程的圍巖分級(jí)與設(shè)計(jì)計(jì)算方法的研究，包括：改進(jìn)巖石地鐵工程圍巖分級(jí)的基本質(zhì)量指標(biāo)；考慮跨度對(duì)圍巖分級(jí)的影響；初襯混凝土的抗剪強(qiáng)度；巖石地鐵工程設(shè)計(jì)計(jì)算方法等。 論文的研究成果如下： （1）采用能量原理自編程序，研究不同卸荷條件下大理巖卸荷破壞過程中的能量演化規(guī)律，取得以下主要研究成果：巖樣卸荷破壞過程的軸向吸收能量曲線非線性變化，經(jīng)歷了緩慢增長-快速增長-緩慢增長-釋放的演化過程�？偰芰壳�經(jīng)歷了緩慢增長-快速增長-緩慢減小-釋放等階段。不同卸荷應(yīng)力路徑對(duì)破壞過程中能量演化規(guī)律的影響主要表現(xiàn)在屈服弱化階段。圍壓高的巖樣消耗更多的能量，軸向能量曲線增長速率增加；卸荷速率越低，軸向能量增長速率升高，卸荷點(diǎn)處軸向能量曲線轉(zhuǎn)折更明顯；卸荷水平接近巖樣承載能力峰值時(shí)，軸向能量增長速率增大，總能量曲線負(fù)向增長速率高，巖樣破壞越劇烈。 （2）研究不同卸荷條件下巖樣破壞過程中的聲發(fā)射特征演化規(guī)律，采用分形的方法自編程序進(jìn)一步量化聲發(fā)射特征，取得以下主要研究成果：不同卸荷路徑試驗(yàn)過程中，聲發(fā)射事件計(jì)數(shù)率最大值都出現(xiàn)在巖樣破壞處，達(dá)到最大值前，巖樣均會(huì)出現(xiàn)一段聲發(fā)射相對(duì)平靜期。圍壓越高，巖樣的聲發(fā)射活動(dòng)水平越高，聲發(fā)射相對(duì)平靜期會(huì)縮短，聲發(fā)射事件最大值也增加；卸荷速率越高，相對(duì)平靜期的振鈴計(jì)數(shù)率越高，持續(xù)時(shí)間越短；越接近巖樣承載力峰值卸荷，巖樣破壞前的聲發(fā)射事件相對(duì)平靜期持續(xù)時(shí)間越短。巖樣破壞前存在聲發(fā)射分維值較低區(qū)域，破壞處附近的分維值，加軸壓、卸圍壓路徑＞恒軸壓、卸圍壓路徑＞常規(guī)三軸路徑。 （3）基于顆粒流方法，利用FISH語言實(shí)現(xiàn)大理巖加、卸荷破壞過程數(shù)值模擬，從細(xì)觀角度有利地補(bǔ)充宏觀的室內(nèi)試驗(yàn)分析，其創(chuàng)新點(diǎn)為：通過FISH語言設(shè)計(jì)不同的卸荷應(yīng)力路徑方案，有效實(shí)現(xiàn)巖樣復(fù)雜卸荷試驗(yàn)的數(shù)值模擬，研究卸荷破壞過程中摩擦能、動(dòng)能、黏結(jié)能與應(yīng)變能等細(xì)觀能量與應(yīng)力路徑之間的聯(lián)系，，破壞過程中細(xì)觀裂紋數(shù)與巖石破壞前兆的關(guān)系，以及巖石微觀裂紋產(chǎn)生、發(fā)展與貫通的過程。通過不同卸荷應(yīng)力路徑試驗(yàn)?zāi)M分析，給出細(xì)觀參數(shù)與巖樣宏觀強(qiáng)度參數(shù)之間的非線性關(guān)系；圍壓主要影響顆粒間摩擦滑動(dòng)引起的摩擦能，進(jìn)而改變?cè)嚇拥钠茐男问�。卸荷速率越高，試樣�?nèi)部裂紋發(fā)展越不充分，黏結(jié)能越少；試樣破壞時(shí)顆粒運(yùn)動(dòng)引起的動(dòng)能越大。卸荷破壞過程是由壓破壞形成貫通剪切面，與拉剪破壞共同作用引起試樣破壞。壓破壞剪切面都是由破壞面兩端向中間發(fā)展，逐漸貫通，試樣內(nèi)部主要破壞形式都表征為壓力引起的損傷破壞，拉剪破壞伴隨壓破壞，在壓破壞裂紋尖端有集中的趨勢。 （4）從細(xì)觀角度分析卸荷破壞過程，并通過實(shí)例驗(yàn)證圍巖卸荷分析的可行性，其主要結(jié)論：經(jīng)典強(qiáng)度準(zhǔn)則中Mogi-Coulomb準(zhǔn)則相對(duì)適合加軸壓、卸圍壓路徑下的試驗(yàn)分析；將裂紋考慮成橢圓形，從細(xì)觀力學(xué)和單連通域的解析函數(shù)出發(fā)分析卸荷路徑下的強(qiáng)度準(zhǔn)則；從單元體裂紋生成的復(fù)合應(yīng)力狀態(tài)出發(fā)，建立卸荷過程中的應(yīng)力-應(yīng)變關(guān)系。 （5）在國標(biāo)《工程巖體分級(jí)標(biāo)準(zhǔn)》和《地下工程圍巖穩(wěn)定分析與設(shè)計(jì)理論》一書對(duì)國標(biāo)改進(jìn)意見的基礎(chǔ)上，提出巖石地鐵工程圍巖分級(jí)設(shè)想，其主要結(jié)論：一是對(duì)圍巖分級(jí)表中圍巖定性特征進(jìn)行了改進(jìn)和調(diào)整，改進(jìn)了各級(jí)圍巖基本質(zhì)量BQ值，使定性分級(jí)和定量分級(jí)協(xié)調(diào)一致，發(fā)展與完善了圍巖巖體基本質(zhì)量標(biāo)準(zhǔn)。二是在圍巖分級(jí)中反映了地下工程跨度對(duì)圍巖穩(wěn)定性的影響，提出按巖體質(zhì)量和工程跨度為基準(zhǔn)的圍巖分級(jí)思想，結(jié)合地鐵工程特點(diǎn)，給出區(qū)間隧道與車站隧道的亞級(jí)分級(jí)，量化了亞級(jí)的基本質(zhì)量指標(biāo)。采用了由安全系數(shù)反映圍巖自穩(wěn)性的量化指標(biāo)和通過反算得到各級(jí)圍巖物理力學(xué)參數(shù)。對(duì)重慶軌道1#、6#線的巖體物理力學(xué)參數(shù)和圍巖分級(jí)進(jìn)行了調(diào)研，采用本文提出的分級(jí)方法與國標(biāo)相比：區(qū)間隧道砂巖由III、IV級(jí)圍巖提升為II、III級(jí)圍巖；區(qū)間隧道砂質(zhì)泥巖有1/3的Ⅳ級(jí)圍巖提升為Ⅲ級(jí)圍巖；車站隧道砂巖約有80%的IV級(jí)圍巖提升為III級(jí)圍巖。 （6）采用數(shù)值極限分析新方法發(fā)展與完善了地鐵隧道的設(shè)計(jì)計(jì)算方法，提出了合理的設(shè)計(jì)計(jì)算參數(shù)和初襯二襯的計(jì)算方法。其主要結(jié)論是：一是依據(jù)現(xiàn)有試驗(yàn)設(shè)備條件，提出了將直剪試驗(yàn)與單軸抗壓試驗(yàn)相結(jié)合的混凝土剪切試驗(yàn)方法，從而確定不同強(qiáng)度等級(jí)混凝土剪切強(qiáng)度指標(biāo)c、φ值；二是依據(jù)摩爾庫倫公式和數(shù)值方法，提出混凝土剪切強(qiáng)度和抗壓強(qiáng)度之間的關(guān)系，驗(yàn)證了混凝土剪切強(qiáng)度試驗(yàn)結(jié)果的可靠性，并將混凝土強(qiáng)度的標(biāo)準(zhǔn)值與設(shè)計(jì)值換算成剪切強(qiáng)度的標(biāo)準(zhǔn)值與設(shè)計(jì)值。結(jié)合實(shí)例，討論了荷載釋放量的確定、不同深淺埋分界標(biāo)準(zhǔn)的適用范圍、應(yīng)力釋放后的圍巖安全系數(shù)、初襯圍巖與二襯結(jié)構(gòu)的安全系數(shù)計(jì)算過程。最后對(duì)重慶地鐵、青島地鐵車站進(jìn)行的計(jì)算分析表明，Ⅲ級(jí)圍巖以上可比現(xiàn)行襯砌厚度約減少30%，而Ⅳ、Ⅴ級(jí)圍巖初襯厚度或強(qiáng)度尚需適當(dāng)增加，以確保施工安全。
[Abstract]:This paper consists of two parts : one is the complex loading and unloading process for the underground engineering excavation , especially the unloading process , the rock failure mechanism under the unloading path is clarified , and the damage mechanism of the rock macro - meso - view under different unloading paths is emphatically studied , including : the energy evolution law during the destruction of different unloading conditions ;
Evolution law and quantitative analysis of acoustic emission characteristics during rock unloading and destruction
Based on the numerical simulation of the rock unloading damage process in rock metro engineering , the study on the calculation methods of surrounding rock classification and design of rock metro engineering is carried out by using numerical limit analysis method , including the improvement of the basic quality index of rock classification of rock metro engineering .
Considering the influence of span on the grading of surrounding rock ;
Shear strength of initial lining concrete
Calculation methods of rock subway engineering design and so on .

The research results are as follows :

( 1 ) The energy evolution law in the process of unloading the marble under different loading conditions is studied by using the self - compiled program of energy principle , and the following main research results are obtained : the nonlinear change of the axial absorption energy curve of the rock sample unloading damage process , and the evolution process of slow growth - fast growth - slow growth - release is experienced .
The lower the unloading speed , the increasing rate of axial energy increase , the turning of the axial energy curve at the unloading point is more obvious ;
When the unloading level is close to the peak load carrying capacity , the increasing rate of axial energy increases , the negative growth rate of the total energy curve is high , and the more severe the rock sample damage .

( 2 ) To study the evolution of acoustic emission characteristics during rock sample destruction under different loading conditions , and further quantify the acoustic emission characteristics by fractal method .
The higher the unloading rate , the higher the ringing count rate of the relative calm period , the shorter the duration ;
The closer to the peak unloading of rock - like bearing capacity , the shorter the relative calm period of the acoustic emission events before the rock sample destruction . There is a lower area of the sound emission fractal dimension before the rock sample damage , the fractal dimension near the destruction point , the adding shaft pressure , the pressure relief path of the pressure relief , the constant axial pressure , the pressure relief path of the pressure relief and the conventional three - axis path .

( 3 ) Based on the particle flow method , the numerical simulation of loading and unloading damage process of marble is realized by FISH language .
The confining pressure mainly affects the friction energy caused by the friction sliding between the particles , and then changes the damage form of the sample . The higher the unloading rate , the less the internal crack development of the sample is , the less the binding energy is ;
The larger the kinetic energy caused by the movement of the particles , the more kinetic energy caused by the movement of the particles when the specimen is damaged . The damage of the specimen is caused by the failure of the breaking surface . The damage of the specimen is caused by the failure of the breaking surface to the middle . The main damage form inside the sample is characterized by the damage caused by the pressure , the shear failure is accompanied by the pressure damage , and there is a concentration trend in the crack tip .

( 4 ) To analyze the unloading damage process from the viewpoint of view angle , and verify the feasibility of surrounding rock unloading analysis by examples . The main conclusions are as follows : the Mogi - Coulomb criterion in the classical strength criterion is relatively suitable for the test analysis under the axial pressure and the pressure relief path ;
taking the crack into an ellipse , analyzing the strength criterion under the unloading path from the analytic function of the meso - mechanics and the single - connected domain ;
The stress - strain relationship in unloading process is established based on the composite stress state generated by unit crack .

( 5 ) Based on the improvement of the surrounding rock mass , the paper puts forward the improvement and adjustment of the surrounding rock stability in the rock mass classification table . The main conclusions are as follows : 1 . The influence of underground engineering span on the stability of surrounding rock is proposed .
Grade 鈪

本文編號(hào)：1899095