不同型式岩栓及預力地錨於砂、泥岩層內之行為特性探討

Study on Characteristics of Applying Different Types of Rock Bolts and Prestressed Anchors in Sandstone and Mudstone Alternation

劉弘祥(H. S. Liu) ； 黃崇仁(C. J. Huang) ； 陳怡名(Y. M. Chen)

《地工技術》 55期 (1996/06) Pp. 89-100

https://doi.org/10.30140/SG.199606.0008

摘要

岩栓及預力地錨之行為及效用受地層性質及施工方式影響極大，且近年來其型式已有多方之發展。台灣西南部麓山地區多含地質年代輕之六雙層膠結鬆散砂泥岩互層，其粉土含量及PH值均高，且含膨脹性粘土礦物，具吸水回脹崩解特性，因此乾燥時強度高，一旦受水浸蝕強度則驟降。由於以往於類似地層之岩栓、預力地錨施工案例較少，為瞭解於此種地層開挖隧道及邊坡穩定工程，使用岩栓及預力地錨之適用性，特將台灣常用之九種不同型式岩栓及六種不同型式預力地錨，於現地施作及辦理現地試驗，並探討下列特性：（1）.鑽孔作業、錨碇段材料、型式、灌漿方法，對岩栓及預力地錨拉力行為之影響；（2）.在砂泥岩互層中岩栓及預力地錨長期潛變效應；（3）.設計安全係數之考慮。試驗結果顯示採用氣壓乾式鑽孔及錨碇段以擴孔錨碇型式之岩栓及預力地錨，可於砂泥岩互層中達到較理想之拉力強度；另考量長期潛變效應，應採適當之鑽孔、安裝方式及安全係數，方能確切掌握砂泥岩互層中岩栓及預力地錨之拉力行為及安全性。

關鍵字

砂泥岩互層 ； 岩栓 ； 預力地錨 ； 擴孔錨碇型 ； 乾式鑽孔 ； 潛變

並列摘要

The effects of using rock bolts and prestressed anchors are highly affected by the geological conditions and the construction processes. In recently years, many types of rock bolts and prestressed anchors have been developed in Taiwan. The young Liushuang Formation of the western foothills geological province in southwestern Taiwan is composed of loosely cemented sandstone and mudstone alternations. Both of their PH value and silt content are high. These alternations also contain expansive clay minerals, and thus show slaking through absorption of water. In consequence, these rocks show high strength when dry, but the strength drops drastically when wet. There is very little case history of engineering application in this rock formation. In order to gain some engineering insights to such rock formations during tunnel excavation and slope protection, in -situ tests were conducted on nine types of rock bolts and six types of prestressed anchors. During these tests, the following engineering characteristics were studied: (1). The effects of drilling operation, materials for the fixing section, type of bolt or anchor, and grouting method on the pulling behavior of rock bolts and prestressed anchors; (2) . Long term creep effects when rock bolts or prestressed anchors are installed in sandstone and mudstone alternations; and (3). Considerations for design safety factor.The test results indicated that applying an expansion end rock bolts and prestressed anchors through dry drilling of boreholes would achieve a more desirable pulling strength in the sandstone and mudstone alternations. Taking long term creep into consideration, appropriate drilling of borehole, adequate installation method and safety factor will enable correct mastering of the pulling behavior of the rock bolts and prestressed anchors in sandstone and mudstone alternations.

並列關鍵字

sandstone and mudstone alternations ； rock bolt ； prestressed anchor ； expansion anchor type ； dry drilling of borehole ； creep