發(fā)布時(shí)間：2018-11-20 04:55

【摘要】：在巖石力學(xué)的研究中,關(guān)于巖體內(nèi)原生裂隙的啟裂、擴(kuò)展、連接及貫通特性一直是研究的熱點(diǎn)與難點(diǎn)。對(duì)于三維裂隙巖體問(wèn)題的研究,以往通常進(jìn)行了二維簡(jiǎn)化,并在試驗(yàn)與數(shù)值模擬等方面都取得了較為系統(tǒng)的研究成果。但通過(guò)二維簡(jiǎn)化模型并不能全面描述多裂紋擴(kuò)展與貫通過(guò)程的三維信息。為此,本文旨在通過(guò)三維裂紋相似模型試驗(yàn),研究三維裂紋擴(kuò)展、連接、貫通的機(jī)理及裂隙巖體的損傷斷裂特性,研究結(jié)果可在巖體工程的設(shè)計(jì)、施工和穩(wěn)定性分析等方面作為一定參考。為直觀、清晰地觀察三維裂紋的擴(kuò)展、連接和貫通現(xiàn)象,選擇了透明性良好的有機(jī)玻璃材料(PMMA)。另外,PMMA在-50℃低溫下具有類(lèi)似于巖石的脆性特征。為更好描述試驗(yàn)現(xiàn)象,對(duì)單軸壓縮條件下幾種新生裂紋的相關(guān)特征進(jìn)行了統(tǒng)一定義,包括:翼裂紋(包裹式與劈裂式)、花瓣?duì)盍鸭y、貝殼狀裂紋等。本文依次設(shè)計(jì)了一根、兩根、四根裂紋布置方式,且裂紋按不同角度及外端距進(jìn)行布置,本文的主要結(jié)論如下:①實(shí)驗(yàn)過(guò)程中主要觀察到了三類(lèi)裂紋:翼裂紋(包裹式與劈裂式)、花斑狀裂紋、貝殼狀裂紋。②三維裂紋的啟裂基本都出現(xiàn)在預(yù)制裂紋尖端,首先出現(xiàn)翼型裂紋,傾角較小時(shí),裂紋啟裂方向垂直于預(yù)制裂紋面;傾角較大時(shí),啟裂方向逐漸向豎直方向靠近。③裂紋的擴(kuò)展形態(tài)主要受預(yù)制裂紋傾角大小的控制,A、B、C三組試樣都呈現(xiàn)這一規(guī)律,30°布置時(shí)呈包裹式擴(kuò)展,45°、60°及90°布置時(shí)呈劈裂式擴(kuò)展。④隨著傾角增大,試件的峰值強(qiáng)度逐漸降低;45°布置下,最容易出現(xiàn)啟裂與擴(kuò)展現(xiàn)象;裂紋傾角為0°時(shí),出現(xiàn)的現(xiàn)象并不明顯。⑤隨著傾角與外端距的變化,峰值應(yīng)力、啟裂應(yīng)力、啟裂應(yīng)力水平都呈現(xiàn)一定規(guī)律性變化,這種規(guī)律與類(lèi)似二維裂紋試驗(yàn)所得規(guī)律基本吻合。⑥利用SPH程序進(jìn)行了4根裂紋45°布置下三維裂紋啟裂、擴(kuò)展、連接過(guò)程的簡(jiǎn)要模擬,其擴(kuò)展規(guī)律與試驗(yàn)現(xiàn)象具有一定的吻合度,但模擬得到的反翼型裂紋未能在試驗(yàn)中觀測(cè)到。
[Abstract]:In the study of rock mechanics, the characteristics of initiation, expansion, connection and penetration of primary fractures in rock are always hot and difficult. For the study of three-dimensional fractured rock mass, two-dimensional simplification is usually carried out in the past, and more systematic research results have been obtained in the aspects of experiment and numerical simulation. However, the two-dimensional simplified model can not fully describe the three-dimensional information of the process of multi-crack propagation and penetration. Therefore, this paper aims to study the mechanism of crack propagation, connection, penetration and damage and fracture characteristics of fractured rock mass through three-dimensional crack similarity model test. The results can be used in the design of rock mass engineering. Construction and stability analysis as a certain reference. In order to observe the phenomenon of crack propagation, connection and penetration clearly and intuitively, (PMMA). With good transparency was selected. In addition, PMMA has a brittleness similar to that of rock at-50 鈩，

本文編號(hào)：2343809