【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、擴展、連接及貫通特性一直是研究的熱點與難點。對于三維裂隙巖體問題的研究,以往通常進(jìn)行了二維簡化,并在試驗與數(shù)值模擬等方面都取得了較為系統(tǒng)的研究成果。但通過二維簡化模型并不能全面描述多裂紋擴展與貫通過程的三維信息。為此,本文旨在通過三維裂紋相似模型試驗,研究三維裂紋擴展、連接、貫通的機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、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展、連接和貫通現(xiàn)象,選擇了透明性良好的有機玻璃材料(PMMA)。另外,PMMA在-50℃低溫下具有類似于巖石的脆性特征。為更好描述試驗現(xiàn)象,對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)、花瓣狀裂紋、貝殼狀裂紋等。本文依次設(shè)計了一根、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實驗過程中主要觀察到了三類裂紋: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,裂紋啟裂方向垂直于預(yù)制裂紋面;傾角較大時,啟裂方向逐漸向豎直方向靠近。③裂紋的擴展形態(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°布置時呈包裹式擴展,45°、60°及90°布置時呈劈裂式擴展。④隨著傾角增大,試件的峰值強度逐漸降低;45°布置下,最容易出現(xiàn)啟裂與擴展現(xiàn)象;裂紋傾角為0°時,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)律與類似二維裂紋試驗所得規(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、擴展、連接過程的簡要模擬,其擴展規(guī)律與試驗現(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中觀測到。
[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：2343809