【摘要】：砂性隧道圍巖具有松散、破碎、低粘聚力等特性。其破壞往往具有突發(fā)性、持續(xù)性、階段性、對擾動敏感性等特點。目前普遍采用的基于連續(xù)性假定的研究方法在砂性隧道圍巖中的適用性受到限制,因此有必要從圍巖細(xì)觀結(jié)構(gòu)出發(fā),對其穩(wěn)定性進行深入研究,在此基礎(chǔ)上再進一步對圍巖宏觀結(jié)構(gòu)特性和安全性進行評價。 首先,通過對砂性隧道圍巖細(xì)觀結(jié)構(gòu)的研究,提出了圍巖顆粒體系失穩(wěn)破壞的細(xì)觀結(jié)構(gòu)模型,得到了圍巖細(xì)觀結(jié)構(gòu)參數(shù)與宏觀強度參數(shù)之間的量化關(guān)系。建立了基于細(xì)觀結(jié)構(gòu)失穩(wěn)層面的砂性圍巖破壞準(zhǔn)則。其次,從細(xì)觀顆粒接觸力穩(wěn)定性方面對圍巖松動區(qū)產(chǎn)生機理和范圍進行了研究,得到了隧道圍巖松動區(qū)范圍分析過程和方法,對各影響因素進行了詳細(xì)分析。然后,在以上兩階段工作基礎(chǔ)上,對圍巖結(jié)構(gòu)特性進行了深入研究,提出了復(fù)合拱結(jié)構(gòu)的思想,并對其形成機理、發(fā)展演化規(guī)律、穩(wěn)定性判別及其影響因素進行了分析。最后,針對砂性圍巖穩(wěn)定性控制原則和措施進行研究,得到砂性圍巖的加固原則,并重點對注漿加固、鎖腳錨桿、自適應(yīng)支護結(jié)構(gòu)三個方面進行論證。主要工作和結(jié)論如下： 1.砂性圍巖宏觀上表現(xiàn)出的破壞特性與其細(xì)觀結(jié)構(gòu)密切相關(guān),通過對顆粒細(xì)觀結(jié)構(gòu)在荷載作用下的演化規(guī)律進行研究,創(chuàng)造性地提出了顆粒體系抗剪承載系數(shù)的概念。這一參數(shù)可以構(gòu)建起細(xì)觀結(jié)構(gòu)參數(shù)與宏觀強度參數(shù)之間的聯(lián)系,在此基礎(chǔ)上建立了兩種細(xì)觀結(jié)構(gòu)模型—“楔塊-滾動模型”和“塑性鉸-楔塊模型”。細(xì)觀模型反映出砂性圍巖的剪切破壞是應(yīng)力重分布和顆粒重排列的過程,該過程中部分顆粒摩擦角不斷弱化,而承載顆粒數(shù)量逐漸增多,土體內(nèi)部應(yīng)力分布逐漸均勻,剪切面承載力呈現(xiàn)先增大后減小的漸進變化過程。 2.砂性隧道圍巖破壞除傳統(tǒng)意義上的剪切破壞之外,還會發(fā)生顆粒局部失穩(wěn),在粘聚力較小的情況下,顆粒力鏈的局部失穩(wěn)相對剪切破壞更容易發(fā)生。影響松動區(qū)范圍和形態(tài)的因素主要有圍巖的粘聚力、內(nèi)摩擦角,側(cè)壓力系數(shù),以及圍巖所處荷載環(huán)境等因素。其中側(cè)壓力系數(shù)對松動區(qū)形態(tài)影響顯著,其他參數(shù)則主要影響松動區(qū)范圍,對基本形狀改變不明顯。 3.砂性圍巖結(jié)構(gòu)特性可用復(fù)合拱進行描述,復(fù)合拱的形成以及發(fā)展演化規(guī)律與圍巖的三種破壞模式相對應(yīng)：上部垮落-拱結(jié)構(gòu)承載主體向上移動；拱腳失穩(wěn)-拱跨度會向兩側(cè)移動,后續(xù)再發(fā)生高度的向上移動；下部滑移-拱結(jié)構(gòu)同時在跨度和高度上向外擴展。在此過程中,設(shè)計了一種基于鏈?zhǔn)椒磻?yīng)原理的破壞面搜索算法,可以對隧道下部滑移區(qū)進行全局搜索判斷。該算法通過發(fā)散點數(shù)量、發(fā)散方位、傳播距離等進行計算控制,可以有效的對潛在滑移區(qū)域進行高效搜索。 4.砂性隧道圍巖的失穩(wěn)破壞特征與其碎散的細(xì)觀結(jié)構(gòu)密切相關(guān),在進行穩(wěn)定性控制措施的制定過程中,也應(yīng)針對這一特點進行相應(yīng)設(shè)計。其中注漿加固、鎖腳錨桿、自適應(yīng)支護是比較有效的控制措施。針對性地提出了一種自適應(yīng)支護結(jié)構(gòu)設(shè)計構(gòu)想,該結(jié)構(gòu)對圍巖變形具有自適應(yīng)性,對施做時機不敏感,能夠保證較高的前期支護剛度和穩(wěn)定的后期自身受力特性。
[Abstract]:The surrounding rock of sandy tunnel has the characteristics of loose, broken, low viscosity and cohesive force. Its failure tends to have characteristics such as bursty, persistent, stage, disturbance sensitivity and so on. At present, the applicability of the research method based on continuity assumption is limited in the surrounding rock of sandy tunnel. Therefore, it is necessary to conduct deep research on the stability of surrounding rock from the meso-structure of surrounding rock, and then evaluate the macro-structure characteristics and safety of surrounding rock. First, by studying the meso-structure of surrounding rock of sandy tunnel, the meso-structure model of the failure of surrounding rock particle system is put forward, and the quantification of meso-structural parameters and macro-intensity parameters of surrounding rock is obtained. The damage of surrounding rock is established based on meso-structure instability. Secondly, the mechanism and scope of the surrounding rock loosening zone are studied from the aspect of the stability of the micro-particle contact force, and the process and method of the range analysis of the surrounding rock of the tunnel are obtained, and the influencing factors are discussed in detail. Then, on the basis of the above two stages, the characteristics of surrounding rock structure are studied deeply, the idea of compound arch structure is put forward, and its forming mechanism, evolution rule, stability discrimination and its influencing factors are analyzed. Finally, the paper studies the stability control principles and measures of sand rock surrounding rock, and obtains the reinforcement principle of sand rock surrounding rock, and puts emphasis on the three aspects of grouting reinforcement, locking foot anchor rod and self-adaptive supporting structure. Demonstration. Main work and conclusions The damage characteristics of sand-like surrounding rocks are closely related to their meso-structure, and through the study of the evolution law of the micro-structure of the particles under load, the authors creatively put forward the anti-shear bearing of the particle system. In this paper, the relation between microstructure parameters and macro-intensity parameters can be constructed. Based on these parameters, two kinds of meso-structural models, such as 鈥渨edge block-rolling model鈥，

本文編號：2305570