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As the surface areas of cities throughout the world become ever more congested/ and the quality of life deteriorates, those in authority are increasingly turning to the engineering use of created space underground. Transportation systems have been located at least partly underground for generations - particularly in London. Dozens of cities throughout the rest of the world are presently engaged in underground construction, not only for rail transportation schemes, but also for communications purposes, water supply, sewerage, roads, car parks, shopping centres, concert halls, museums and art galleries. Outside the cities underground construction continues to be used for hydro-electric purposes, gas storage, inter-city highways and rail systems, and for nuclear waste storage. This international engineering research study looks at the risks involved in underground construction, and in particular the nature of risks to people directly engaged on this work and to other persons who may be affected by the works and also looks at the nature of risks to the built and natural environment. The study brings together many details of past incidents and disasters that have occurred internationally, and from a broad analysis of the types and causes of failures of one type or another, looks to how such incidents may be prevented in the future. The identification and control of risk in underground engineering projects is seen as the duty and responsibility of all the main parties to the project - the client or promoter of the project, the engineering designers, and those chosen to undertake the construction work. Key components of a broad risk control strategy are described which are applicable regardless of the project's location or what the final purpose of the underground construction work might be. Within this study there are two international Case Studies to illustrate good and poor practice in the identification and control of risk in these types of projects.

As a result of tunnel construction, the ground level surface above will tend to collapse downward as the soil seeks to refill the missing tubular cavity. Many infrastructures that were originally built on that surface may also fall slightly or severely depending on the engineering design and execution of the tunneling project. Engineers then must factor in the development of ground subsidence, examining geotechnical and geological issues to construct a model that would otherwise predict the extent of vertical settlements. Their predictions could help to assess potential damages and make corrective actions. In this thesis submission, analytical methods from the classical elasticity were used to estimate surface displacements for a prospective tunnel. The analytical equation tied in the method of virtual images originating from Sagaseta with the classical Kirsch elastic solutions for stress-displacements of an infinite plate with hole in order to establish a solution of half-space. This approach will be similar to what Verruijt-Booker had developed after Sagaseta but will include higher-order terms to simulate an excavation process in a longitudinal direction below ground and thereby obtain a new subsidence equation including ground parameters associated with tunnel shape changes occurring at its base, springline (sideway point) and crown (top). These parameters were not previously reported by the Verruijt-Booker work or from current technical literature. In addition, the prescribed solution could include any Poisson’ ratios in which only the original Verruijt-Booker could be found correct for only incompressibility conditions (υ = 0.5). The Verruijt-Booker equation considered deep tunnels only. An extra term influencing the subsidence was included in the modified solution which is significant for shallow tunnels. The derived equations were applied to calculate surface deflections using data from a tunnel construction project to test its viability. Comparison analysis was made with the three methods to be described- Peck, Sagaseta, and Verruijt-Booker. In addition, a parametric study was made to examine the amount of subsidence changed when deciding to construct a tunnel from a shallow to deeper zone. Finally, a qualitative study of the derived equation and Verruijt-Booker was conducted to assess potential subsidence behaviour between shallow and deep tunnels.

As a result of tunnel construction, the ground level surface above will tend to collapse downward as the soil seeks to refill the missing tubular cavity. Many infrastructures that were originally built on that surface may also fall slightly or severely depending on the engineering design and execution of the tunneling project. Engineers then must factor in the development of ground subsidence, examining geotechnical and geological issues to construct a model that would otherwise predict the extent of vertical settlements. Their predictions could help to assess potential damages and make corrective actions. In this thesis submission, analytical methods from the classical elasticity were used to estimate surface displacements for a prospective tunnel. The analytical equation tied in the method of virtual images originating from Sagaseta with the classical Kirsch elastic solutions for stress-displacements of an infinite plate with hole in order to establish a solution of half-space. This approach will be similar to what Verruijt-Booker had developed after Sagaseta but will include higher-order terms to simulate an excavation process in a longitudinal direction below ground and thereby obtain a new subsidence equation including ground parameters associated with tunnel shape changes occurring at its base, springline (sideway point) and crown (top). These parameters were not previously reported by the Verruijt-Booker work or from current technical literature. In addition, the prescribed solution could include any Poisson’ ratios in which only the original Verruijt-Booker could be found correct for only incompressibility conditions (υ = 0.5). The Verruijt-Booker equation considered deep tunnels only. An extra term influencing the subsidence was included in the modified solution which is significant for shallow tunnels. The derived equations were applied to calculate surface deflections using data from a tunnel construction project to test its viability. Comparison analysis was made with the three methods to be described- Peck, Sagaseta, and Verruijt-Booker. In addition, a parametric study was made to examine the amount of subsidence changed when deciding to construct a tunnel from a shallow to deeper zone. Finally, a qualitative study of the derived equation and Verruijt-Booker was conducted to assess potential subsidence behaviour between shallow and deep tunnels.

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This thesis project was conducted in connection with the project, Stockholm’s future sewer pipeline, which is a planned sewer pipe that will run through a tunnel from western to southern Stockholm. This tunnel will pass under Lake Mälaren between Eolshäll and Smedslätten, where there are two faults indicated on the geological map, that could affect the tunnelling and create risks during the construction. Geophysical- and water-loss measurements along with core drilling have been carried out in the area. The objectives of this thesis are to create a structural and engineering geological understanding of the passage beneath Lake Mälaren based on drill core mapping, field work, data from previous investi-gations and 2D-models of the tunnel excavation both within and outside the indicated fault zone. The core mapping supports the existence of one fault zone, which is indicated on the geological map supported by water-losses at several places along the drill core as well as core losses. Field work indi-cated the existence of a conjugate fracture sets.The 2D-models present plastic behaviour of the rock in the fault zone as the worst case scenario during excavation with the highest deformation displacement. The excavation procedure and the tunnel form also play a significant role. Since this thesis highlights some significant risks and problems that can occur during tunnelling, its findings may be useful during the tunnel construction. / Denna uppsats är skriven med koppling till projektet, Stockholms framtida avloppsledning, vilket inkluderar en ny tunnel för transport av avloppsvatten från västra till södra Stockholm. Tunneln kommer att passera under Mälaren mellan Smedslätten och Eolshäll, där det är två förkastningar indikerade på geologiska kartor som kan orsaka stora risker för byggnationen av tunneln. Geofysiska mätningar, kärnborrning och vattenförlustmätning har tidigare utförts i området. Målen för denna uppsats är att skapa en geologisk- och bergmekanisk förståelse för tunnelpassagen under Mälaren utifrån kärnkartering, fältarbete, data från tidigare undersökningar och 2D-modeller av tunneluttag i den indikerade zonen och utanför. Kärnkarteringen stödjer existensen av en förkastningszon som finns på den geologiska kartan. Flertalet vattenförluster är indikerade längs med hela kärnan tillsammans med en del förekomster av kärnförluster. Fältarbetet indikerar på förekomst av ett konjugerande sprickset. 2D-modeller över tunneln visade att olika egenskaper på berget samt hur uttaget av tunneln sker har betydelse för deformationernas storlek. Den här uppsatsen belyser några viktiga problem och risker som kan uppstå under tunnelbyggnationen, dessa upptäckter kan därför vara användbara och värdefulla under hela byggnationen.

Syftet med detta examensarbete är att studera vilka vattenföroreningar som uppstår i samband med tunnelbyggen, vilka krav som miljömyndigheterna ställer i sammanhanget och vilka reningsåtgärder som har vidtagits för att möta dessa krav samt att föreslå ytterligare reningsåtgärder. Arbetet har utförts som en jämförande litteraturstudie av befintlig dokumentation för tolv olika tunnelbyggen. Vid ett tunnelbygge används stora mängder kylvatten till bergborrningsmaskiner. Detta vatten avleds tillsammans med inläckande grundvatten och släpps efter rening ut till en recipient. Föroreningarna i vattnet från tunneln består i huvudsak av olja, suspenderade partiklar och lösta kväveföreningar. I dagsläget används mekanisk rening för att reducera mängden olja och suspenderade partiklar i vattnet. Kväveutsläppet minskas framförallt genom förebyggande åtgärder för att undvika kvävehaltigt sprängämnesspill. Dagens reningsmetoder ger en betydande minskning av utsläppen. Utsläpp av förorenat vatten från ett tunnelbygge kan ge upphov till temporär miljöpåverkan i recipienten. Miljömyndigheternas krav på begränsningar av utsläpp från tunnelbyggen har i de flesta fall kunnat efterföljas väl. Medianhalten för suspenderat partikulärt material i renat vatten från olika tunnelbyggen varierade mellan 210 mg/l och 485 mg/l. Uppmätta medianvärden för oljehalt varierade mellan 0.28 mg/l och 1.3 mg/l. Medianhalten för olika kväveföreningar i varierade mellan 3.2 mg/l och 100 mg/l. Detta betyder att mellan 0.3 % och 9 % av det kväve som ursprungligen fanns i sprängämnet har hamnat i processvattnet. Enstaka mätvärden för totalkväve, olja och suspenderat material kan visa på upp till 100 ggr högre halt än medianvärdet. l examensarbetet jämförs mängden utsläppta föroreningar till vatten från de olika tunnelbyggena med utsläpp till vatten från vägar, båtar och jordbruk. Ett tunnelbygge leder till utsläpp av samma storlek som det årliga utsläppet från en enstaka bondgård, en motorbåt eller dagvattnet från en kortare motorvägsträcka, med avseende på kväveläckage, oljeutsläpp respektive innehåll av suspenderade partiklar. l examensarbetet beskrivs existerande reningsåtgärder och ges förslag på ytterligare åtgärder som kan vidtas för att minska utsläppen av vattenföroreningar från tunnelbyggen. De föreslagna åtgärderna behandlar optimering av reningsanläggningar, förbättrade kontrollprogram och utsläppsförebyggande insatser. En diskussion förs om möjligheten att förbättra miljöövervakningen vid utsläpp av tunnelvatten genom att ersätta dagens stickprovtagningar med automatiserad kontinuerlig flödesproportionell mätning. / The aim of this thesis is to study which types of water pollution are released during tunnel construction, what demands do the environmental protection authorities have regarding such pollution, what has been done to meet those demands, and finally to suggest additional treatment measures. The work has been performed as a literature study comparing twelve different tunnel projects. When a tunnel is built a lot of water is used to chill the rock-drilling equipment. This water is diverted together with water that originates from an inflow of groundwater, and is released to a recipient after treatment. The water pollution originating from the tunnels consists mainly of oil, suspended material and dissolved nitrogen compounds. Mechanical water treatment measures are used today to reduce the amount of oil and suspended material in the water. Measures are currently taken to limit the accidental release of nitrogen from undetonated explosives to the water. Water treatment today considerably reduces the discharge of pollutants. Discharge of polluted water from tunnel construction can cause temporary environmental effects in the recipient. The demands from the environmental protection authorities for reduction of pollution from tunnel construction have mostly been met. The median content for suspended material in treated water from different tunnel projects varies between 210 mg/l and 485 mg/l. Median content for oil varies between 0.28 mg/l and 1.3 mg/l. The median content for dissolved nitrogen compounds in the water varies between 210 mg/l and 485 mg/l. This means that between 0.3 % and 9 % of the original nitrogen content in the explosives was released in the water. Occasional measurements of nitrogen, oil and suspended material can reach a hundred times higher than the median value. In this thesis, a comparison is made between the amount of pollutants that is discharged into water from tunnel construction and the discharge from roads, boats and agriculture. The total amount of water pollution from a tunnel project is of the same magnitude as the annual discharge from a single farm, a motorboat or the runoff from a short stretch of motorway, regarding nitrogen leakage, oil pollution and content of suspended material respectively. The thesis describes existing water treatment measures and suggestions are made about possible improvements to reduce emissions from tunnel constructions. The suggestions deal with optimisation of water treatment systems, improved surveillance programs and prevention of pollution discharge. A proposal is made about improving environmental surveillance by replacing the currently used random sampling with continuous sampling that is in proportion to discharge.

When a tunnel is built in rock, a type of water is formed as a residual product. This tunnel wateris formed due to construction processes such as drilling requiring water and groundwater thatinfiltrates into the tunnel. The water can cause environmental damage if it is released directlyinto nature and needs to be treated. Usually, therefore, the water is purified regardingconcentrations of suspended matter, oil, metals, nitrogen and basic pH values. In this degree project water analysis data, after a local purification in the tunnel area, has beenobtained from 17 different tunnel projects and processed to look into the water quality in theseprojects. The parameters from the analysis data processed are the concentrations of nitrogen,arsenic, lead, cadmium, chromium, mercury, nickel, zinc, chloride, and suspended matter aswell as pH value and conductivity. The results show a large variation in the average valuesbetween the projects and also that a flocculation step in the purification lowers the averageconcentrations for most metals. An analysis of the suitability of using tunnel water for irrigation and fertilization purposes hasalso been carried out by examining the differences in the characteristics of tunnel watercompared to irrigation and fertilizer sources. The result shows that the average concentrationsof the metals chromium and nickel exceed the average concentrations found in groundwaterand surface water in several projects. This means that the tunnel water with respect to thesetwo metals differs from natural sources of irrigation water. According to FAO's guidelines forirrigation water, the average chloride content and average conductivity of the tunnel water isalso elevated and means that the use of the water for irrigation may need to be partly limited.However, this influence needs to be investigated more for Swedish conditions / När en tunnel byggs i berg uppkommer länshållningsvatten, vilket är en restprodukt som måsteomhändertas. Länshållningsvattnet bildas med anledning av att processer som exempelvisborrning kräver vatten samt att grundvatten tränger in i tunneln. Länshållningsvattnet behöverrenas då det kan påverka miljön negativt om det släpps ut direkt i naturen. Vanligtvis renasdärför vattnet med avseende på suspenderat material, olja, metallhalter, basiska pH-värden ochkvävehalter. I arbetet har vattenanalysdata, efter en lokal rening i tunnelområdet, inhämtats från 17 olikatunnelprojekt och bearbetats för att utreda vattnets innehåll i dessa projekt. De parametrarfrån analysdatan som behandlats är koncentrationerna av kväve, arsenik, bly, kadmium, krom,kvicksilver, nickel, zink, klorid och suspenderat material samt pH-värde och konduktivitet. Iresultatet ses en stor variation i medelvärdena mellan projekten och även att ett flockningssteg ireningen sänker medelhalterna för de flesta metaller. En utredning av lämpligheten att använda länshållningsvatten i bevattnings- och gödslingssyftehar också utförts. Detta gjordes genom att klargöra vilka skillnader som finns i halterna avmetaller, kväve och klorid samt i pH-värdet och konduktiviteten hos länshållningsvatten, jämförtmed befintliga bevattnings- och gödselkällor. Resultatet visar att medelhalterna av metallernakrom och nickel överskrider medelhalterna som finns i grundvatten och ytvatten i flera projekt.Detta innebär att länshållningsvattnet med avseende på dessa två metaller skiljer sig från naturligakällor av bevattningsvatten. Enligt FAO:s riktvärden för bevattningsvatten är länshållningsvattnetsmedelkloridhalt och medelkonduktivitet dessutom förhöjd och innebär att användningen avvattnet till bevattning kan behöva begränsas. Denna påverkan behöver dock utredas mer försvenska förhållanden.