Sweden's population is increasing every year, which means that cities must adapt their infrastructure to be able to follow the demographic trend. In the current situation, Stockholm plans a major expansion of its metro network where evaluating the bedrock quality is of paramount importance. For the new SL metro connection project Gula linjen that stretches between Odenplan and Arenastaden in Solna, the company WSP has previously done quality surveys of the bedrock in the area and dimensioning of the reinforcements in the planned tunnels. Previous survey of the lineaments and weakness zones in the area has been done by means of core drilling and observations in the field. This study examines if the lineaments in the area are associated to any structures below ground surface in the bedrock by examining rock samples from drill cores. A digital presentation tool called Astrock hyperdata report is evaluated in this study by comparing manual measurements of the orientation of the joints in drill cores and the software´s measurements. The studied bedrock in the drill cores varies in quality from very poor to very good. Further examinations of zones of particularly poor rock quality done in this study suggest that the two identified lineaments have different characteristics. The north-west/south-east lineament which runs parallel to the planned metro route is indicated to represent the surface trace of a water-bearing fracture zone in the bedrock. The lineament with the E/W direction is dominated by structures and fault rocks, such as fault gouge and crushed rock in the drill cores, which indicates a brittle deformation zone. For the Gula linjen project, this information becomes useful as the underground reinforcements such as bolting and grouting have to / Sveriges befolkning ökar varje år, vilket gör att städer måste anpassas och expandera för att kunna följa den demografiska utvecklingen. I Stockholm planeras i dagsläget en stor utbyggnad av dess tunnelbanenätverk där det sker mycket arbete kring utvärdering av berggrunden för att göra detta möjligt. För Stockholms lokaltrafiks (SL) tunnelbaneprojektet Gula linjen som ska gå mellan Odenplan och Solna har företaget WSP tidigare gjort kvalitetsundersökningar av berggrunden i området samt dimensioneringar av förstärkningar i de planerade tunnlarna. Studier av svaghetzoner och lineamenten i området har gjorts med hjälp av kärnborrning och fältobservationer. Denna studie undersöker om lineamenten som finns i området är kopplade till strukturer längre ner i berggrunden genom att undersöka bergprov i form av borrkärnor. Som komplement har det digitala redovisningsverktyget Astrock hyperdata report använts för att kunna jämföra strukturer i berget med de egna mätningarna i studien. Programmet kommer även att utvärderas i studien. De erhållna värdena från undersökningen på borrkärnorna varierar i kvalitet från väldigt dålig till väldigt bra. Närmare studier på zoner av särskilt dålig kvalitet tyder på att de båda lineamenten karaktäriseras av olika typer av strukturer. Det nordväst-/sydöstliga lineamentet, som går parallellt med den planerade tunnelbanesträckan, domineras av strukturer som tyder på att lineamentet representerar en vattenförande sprickzon under markytan. I lineamentet med öst-västlig riktning dominerar strukturer som tyder på förekomsten av en förkastningszon. För projektet Gula linjen blir denna information användbar då den vattenförande sprickzonen kan innebära att tunnelförstärkning med injektering måste göras för ytterligare skydd mot vatteninträngning.

Characterization of rock masses and evaluation of their mechanical properties are important and challenging tasks in rock mechanics and rock engineering. Since in many cases rock quality designation (RQD) is the only rock mass classification index available, this paper outlines the key aspects on determination of RQD and evaluates the empirical methods based on RQD for determining the deformation modulus and unconfined compressive strength of rock masses. First, various methods for determining RQD are presented and the effects of different factors on determination of RQD are highlighted. Then, the empirical methods based on RQD for determining the deformation modulus and unconfined compressive strength of rock masses are briefly reviewed. Finally, the empirical methods based on RQD are used to determine the deformation modulus and unconfined compressive strength of rock masses at five different sites including 13 cases, and the results are compared with those obtained by other empirical methods based on rock mass classification indices such as rock mass rating (RMR), Q-system (Q) and geological strength index (GSI). It is shown that the empirical methods based on RQD tend to give deformation modulus values close to the lower bound (conservative) and unconfined compressive strength values in the middle of the corresponding values from different empirical methods based on RMR, Q and GSI. The empirical methods based on RQD provide a convenient way for estimating the mechanical properties of rock masses but, whenever possible, they should be used together with other empirical methods based on RMR, Q and GSI. (C) 2016 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V.