Bisson, Alberto

Murzyn, Ryszard

English

BISSON, ALBERTO

Archivio istituzionale della ricerca - Università di Padova

MSc Ryszard Murzyn (Geo-Inz-Bud, Poland)Dr Eng Alberto Bisson (Dept. ICEA, University of Padova, Italy)ZABEZPIECZENIE OSUWISK PRZY POMOCY KOTEW SIRIVE®LANDSLIDE PROTECTION USING SIRIVE® ANCHORSUNIVERSITY OF PADOVA (ITALY)DEPT. OF CIVIL, ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING, DICEADALLA GASSA SRLGeotechnical Engineering, Cornedo Vicentino (Vicenza, Italy)DALLA GASSA SRLCOMPANY PROFILEMain activities: Excavation support systems: Soil Nailing, Micropiles Landslide stabilization, rockfall protection Foundations engineeringDALLA GASSA SRLSIRIVE® PRODUCTION PRODUCTIONDalla Gassa is the first Italianproducer of self-drilling bars(since 2001) CERTIFICATIONSRINA Certificatein accordance withUNI EN ISO 9001:2008Internal certificateof the completeBar-Nut-Coupling systemDALLA GASSA SRLSIRIVE® QUALIFICATION Qualification as Official Producer of Sirive® Self Drilling Bars in accordance with the Italian Ministerial Decree 14/01/2008 Certificate of qualificationnr. 002/14-AM for the production of “Self-drilling hollow bars S460J0 with continuous threading, nominal diameter 28 to 38 mm, for passive anchors for geotechnical use” Date: September 9, 2014 Internal laboratoryDALLA GASSA SRLRESEARCH & DEVELOPMENT DIVISION Advanced landslide monitoring Sirive®-1 technical validation: a «green» Soil Nailing PhD on Sirive® Floating Anchor for landslide stabilization Research & Development of Sirive® Special Composite Anchor Partnership with University of Padua (Italy), PolytechnicUniversity of Turin (Italy) and University of Agricolture in Krakow (Poland)Production Control Tutorfor Sirive® Self-Drilling BarsDALLA GASSA SRLAWARDS AND PRIZES Bisson A., Dalla Gassa G. (2013)SIRIVE® FLOATING ANCHOR: PATENT AND RESEARCH PROJECTGalileo Innovactors’ Festival 2013 - European exhibition on innovation and technology transferSpecial mention at the Micro-Innovation Marathon (2013) Bisson A., Cola S. (2014)FLOATING ANCHORS FOR THE STABILIZATION OF SLOW-MOVING LANDSLIDESCNG 2014: The geotechnical engineering in the defense of land and infrastructure from natural disasters, XXV National Geotechnical Congress, Baveno (Italy), Vol. 2, pp. 327-334ISBN: 9788897517054Italian Geotechnical Association Award: best paper for technical-scientific content (2014)DALLA GASSA SRLEUROPEAN PATENTS SIRIVE® FLOATING ANCHOREuropean PatentEP 2354323 B1Date of publication and mention of the grant of the patent: April 1, 2015 SIRIVE® COMPOSITE ANCHOREuropean Patent applicationEP 20130157515.1Date of application: March 1,2013The opposition process is still ongoing (2015)CREEPING SLOPEmobreduced mobConfiguration after slopemoving for creepDeformed floatingreinforcementsANCORAGGIO FLOTTANTE SIRIVE®PATENT VI2010A000020Sirive® Floating AnchorEuropean Patent EP 2354323 B1SIRIVE® SPECIAL COMPOSITE ANCHORSIRIVE® SELF-DRILLING BARS Self-drilling hollow bars cemented along the entire profile (nails) Passive reinforcements (not pretensioned) Advantages: Simple and fast execution Increasing of the diameter of the cemented bulb Low costSELF-DRILLING BARSPRODUCTION PROCESS• Mild steel• Large ultimate elongation(Agt=25-30%)• ft/fy=1.4-1.6• Cold rolling• Increase in tensile strength• Increase in yieldstrength• Increase in stiffness• Reduction of plastic strength reserve(ft/fy=1.2)• Reduction ofAgt (5-8%)STRANDSPRODUCTION PROCESS• Harmonic silicon steel with high carbon content (0.8-0.9%)• Annealing• Normalizing• Hardening• High strenght• Large deformability in the elastic range• High yield strength• ft/fy lower than mildsteel(1.05-1.25)• Low relaxationSIRIVE® SPECIAL COMPOSITE ANCHORBASIC IDEA Goals: Serviceability limit state: increase of the admissible load at constant elongation in the elastic domain; Ultimate limit state: decrease of the plastic deformations at constant elongation. Basic idea:SELF-DRILLING BAR + STRANDS = SIRIVE® COMPOSITE ANCHORSIRIVE® SPECIAL COMPOSITE ANCHORANALYTICAL MODEL Main hypotheses: Congruence of the coupled system Equilibrium of the coupled system Negligible thermal variations Axial stiffness and elastic modulus equivalence: 𝐹𝑏(𝜎𝐸𝑏 𝜎 ∙ 𝐴𝑏= 𝐹𝑡(𝜎𝐸𝑡 𝜎 ∙ 𝐴𝑡= 𝐹(𝜎𝐸𝐴 𝑒𝑞 𝜎𝑑𝑜𝑣𝑒: 𝐴 = 𝐴𝑏 + 𝐴𝑡𝐹𝑏 𝜎 + 𝐹𝑡 𝜎 = 𝐹 𝜎 = 𝐸𝐴 𝑒𝑞 𝜎 ∙∆𝑙 𝜎𝑙0𝐸𝐴 𝑒𝑞 𝜎 = 𝐸𝑏 𝜎 ∙ 𝐴𝑏 + 𝐸𝑡 𝜎 ∙ 𝐴𝑡 𝐸𝑒𝑞 𝜎 =𝐸𝑏 𝜎 ∙ 𝐴𝑏 + 𝐸𝑡 𝜎 ∙ 𝐴𝑡𝐴𝑏 + 𝐴𝑡SIRIVE® SPECIAL COMPOSITE ANCHOREXPERIMENTAL TESTSMechanical behaviour of R32L Sirive® Self-drilling traditional bar (blue), a 0,6” strand (red) and Sirive® Special R32S Composite Anchor (violet).Force [kN]Agt [%]SIRIVE® SPECIAL COMPOSITE ANCHORINSTALLATION STEPS FOR ROCK SLOPE STABILIZATION STEP 1: Installation of the self-drilling barDrill BitRod SpacerCouplingGroutingSirive®Self-Drilling BarSIRIVE® SPECIAL COMPOSITE ANCHORINSTALLATION STEPS FOR ROCK SLOPE STABILIZATION STEP 2: Installation of strands and washing tubeDrill BitRod SpacerCouplingWashing tubeSirive®Self-Drilling BarStrandsGroutingSIRIVE® SPECIAL COMPOSITE ANCHORINSTALLATION STEPS FOR ROCK SLOPE STABILIZATION STEP 3: The anchor active zone is washed (with water) and the inner cementation removed (only in the active/unstable part of the anchor)Drill BitRod SpacerCouplingStrand cementationin the stable zoneSirive®Self-Drilling BarWashing tubeGroutingSIRIVE® SPECIAL COMPOSITE ANCHORINSTALLATION STEPS FOR ROCK SLOPE STABILIZATION STEP 4: After the grout full maturity, the strands are tensioned at the design loadDrill BitRod SpacerCouplingStrand cementationin the stable zoneSirive®Self-Drilling BarWashing tubeGroutingNutBlockingheadSIRIVE® SPECIAL COMPOSITE ANCHORINSTALLATION STEPS FOR ROCK SLOPE STABILIZATION STEP 5: Injection of cement mixture and complete cementation of the strands within the bar to restorethe full protection of the strandsDrill BitRod SpacerCouplingStrand cementationin the stable zoneSirive®Self-Drilling BarGroutingProtective capNutBlockingheadWashing/Grouting tubeSIRIVE® SPECIAL COMPOSITE ANCHORPROTECTIONSIRIVE® SPECIAL COMPOSITE ANCHORULTIMATE TENSILE LOADSAnchor bartypeUltimatetensile load (*)[kN]R32 Special 550R38 Special 700R51 Special 1100S60 Special 2000S76 Special 3000S90/A Special 4000S90/B Special 5000(*) Minimum warranted loadSirive® Special Composite Anchor S76CROSS SECTIONSIRIVE® SPECIAL COMPOSITE ANCHORACCESSORIES Sirive® Special Head Blocks(custom-made for both active and passive anchor configuration)Sirive® Special Composite Anchor S76SIRIVE® SPECIAL COMPOSITE ANCHORCOST ANALYSISComparison of the cost of 3 alternative anchoring systems for a ultimate tensile strength of 3000 kNDESCRIPTIONCOST [€/meter]Self-drilling barAnchor with 12 0,6”strandsComposite bar 76 8mm thick+8 0,6”strandsBar, Fe55, steel section 1800 mm2 21.06Nr. 8 strands, diameter 0.6” 8.00Bar, Fe55, steel section 5455 mm2 63.83Nr. 12 strands, diameter 0.6” 12.00Accessories and installation 67.00 69.00 42.85Subtotal production costs 130.83 81.00 71.91General costs: 8% 10.47 6.48 5.75Subtotal 141.30 87.48 77.66Profit for the enterprise: 30% 42.39 26.24 23.30TOTAL COST 183.69 113.72 100.96Saving with composite anchor % 45.0 11.2 -SIRIVE® SPECIAL COMPOSITE ANCHORADVANTAGES Minor cost at constant mechanical properties; High ultimate tensile streghtand low elongation(serviceability); Durability (minor cracking, better protection from corrosion); Easy transport and quickinstallation; Anchorage length is adaptable to different geological and geotechnical conditions found in situ; Increased flexural inertia and continuity given by strand to the full reinforcement (improved if compared to simple coupling sleeve).SIRIVE® FLOATING ANCHORSIRIVE® FLOATING ANCHORSEARCH FOR NEW SOLUTIONS Lack of economic resources available to meet the emergency. Search for new types of intervention: Low cost; Quick installation; Environmental care. «Floating Anchor» project: partnership between University of Padova, Province of Vicenza and Dalla Gassa s.r.l. Stabilization of slopes subject to landslides with low to medium depth (up to 25 m deep). SUMMARY: Technical/economical comparison between most commonly used strengthening intervention works; The «floating anchor» tecnique; Advantages.SIRIVE® FLOATING ANCHORTHE BASIC IDEA What type of landslides? Slow/Very slowCruden & Varnes(1996)SIRIVE® FLOATING ANCHORTHE BASIC IDEA Slope stabilization with reinforcement provides for increasing shear strength or reducing the sliding actions along the slip surface with various types of structures: Retaining walls Dowels Micropiles Anchors Soil nailingExisting or possible slidingsurfaceBedrockMax water tableSIRIVE® FLOATING ANCHORTHE BASIC IDEAFillMicropiles structures Retaining walls Alternative to rigid techniques normally used, which have some disadvantages: Need for an accurate assessment of the acting forces (collapse); High stiffness, poor adaptability to any movement of the slope; High internal stresses; Lack of modularity; High costs ...TRADITIONAL REMEDIATION WORKSA COST-EFFECTIVENESS COMPARISON Stabilization of a generic slope with a limited height. Design of the intervention according to Italian NTC 2008. Limit equilibrium (LE) analysis. Assessment of the global safety factor for the rotational instability. Assessment of the intervention cost per linear meter.Formation Type of soilγ[kN/m3]c’[kPa]φ[°]ColluviumSilty clayeysand18 0 28Bedrock Gravel 19 0 38ColluviumResistentsoilTRADITIONAL REMEDIATION WORKSA COST-EFFECTIVENESS COMPARISONN. Type of intervention Characteristics of intervention FSPrice(1)(Euro/m)Price/ΔFS(1)(Euro/m)a Cantilever wallHeight = 5,0 m; Width = 3,5 m; Depth of tooth = 0,7 m1.29 1694 5841b Gabion wall Height = 5,0 m; Width = 4,5 m; base dip = 6° 1.30 2614 8713c Reinforced earth wall Height = 5,0 m; Width = 3,5 m 1.39 1360 3487d DowelsHeight = 2,0 m; Depth = 7,0 m; 1 lines of piles with 0,4 pile/m; D=60 cm; reinforcement rods 16Ø261.58 1781 3071eWall founded on micropilesHeight = 2,8 m; Depth = 4,0 m; 2 micropile lines with spacing i=0,2; 0,66 micropile/m; Dex=114,3 mm; s=6,3 mm; passive anchor R38 spacing 1,5 m; L = 10 m; a = 25°1.60 1420 2367fAnchored micropilesheet-wallHeight = 2,5 m; Depth = 4,2 m; 2 micropile lines with spacing i=0,5; 2 micropile/m; Dex=127 mm; s=8 mm; passive anchor R38 spacing 2,5 m; L = 12 m; a = 30°1.46 1584 3443g Passive nailsL = 6, 6, 6, 9 m; ix= iz =1,6 m; a = 15°; facing with steel net1.39 883 2264“Reinforcement works for the slope stabilization: standard and new approaches for the use of micropiles and anchors”S. Cola, A. Bisson, C. Pilati, S. Frasson, G. Stevan, G. Tessari, ISM 2012: International Workshop on Micropiles, Milan, 2012 Nails are designed to absorb significant horizontal stresses,thus reducing the stresses that induce the viscous motion,in order to slow down the evolution process of the landslides As opposed to active anchors, the floating anchor absorbs a part of the shear stresses induced by the landslide movement by mean of the friction forces activated along its profile  In this way, it transfersto the external platea small tension: it doesnot require a continuousfacing, but only asmall head plateSIRIVE® FLOATING ANCHORA BRIEF INTRODUCTIONCREEPING SLOPEmobreduced mobConfiguration after slopemoving for creepDeformed floatingreinforcementsANCORAGGIO FLOTTANTE SIRIVE®PATENT VI2010A000020Sirive® loating AnchorEuropean Patent EP 2354323 B1SIRIVE® FLOATING ANCHORA BRIEF INTRODUCTION External concrete plate (floating element) + nail (passive) The set is an “energy dissipator” that activates by friction within the moving slope (viscous medium) If the slope deforms and the ground moves, the plate may be englobed into the soilSIRIVE® FLOATING ANCHORA BRIEF INTRODUCTION Single reinforcing elements, each of them designed to absorb a fraction of the shear stress Total ultimate pullout resistance for one element: L upa dxDQQ Head force (external plate)Lateral friction(passive bar)SIRIVE® FLOATING ANCHORA BRIEF INTRODUCTION The system activation occurs with relative displacements at the soil-concrete interface. It may produce: Complete stabilization of the slope: the axial force remains less than the maximum available axial strength; Only deceleration of the slope: activation of the maximum available axial strength; In any case: no structural failure of reinforcements.SIRIVE® FLOATING ANCHORADVANTAGES Flexible, not rigid Modularity, calibration of the intervention work in progress Easy and quick to install Good protection against  corrosion of the bars Low environmental impact (facing ratio about 5-6%) Low costGISBENTI LANDSLIDESIRIVE® SPECIAL COMPOSITE ANCHORS/SIRIVE® FLOATING ANCHORS Location Gisbenti, district of Valli del Pasubio (Vicenza, Italy). Stabilization work placed at the foot of a landslide (autumn 2010), replacing a retaining wall collapsed by slippage due to the landslide. 3 rows of floating anchors (Sirive® Special Composite Anchor S60, ultimate strength 2000 kN), 3 m horizontal spacing, 20 to 40 m long.Formation Soilγ[kN/m3]c'[kPa]φ[°]Colluvium Sandy clay 18 13 20Bed-rock Phyllites 24 150 35Rear rock mass Dolomite 22 300 36Bed-rock(Bisson A. & Cola S., 2014)GISBENTI LANDSLIDESIRIVE® SPECIAL COMPOSITE ANCHORS/SIRIVE® FLOATING ANCHORS Maximum traction forcemobilized at the sliding surface to resist to destabilizing actions. Low axial force behind the plates, due to the balance of tangential shear stresses developed along the soil-grout interface along the bar.VAL MASO LANDSLIDESIRIVE® SPECIAL COMPOSITE ANCHORS/SIRIVE® FLOATING ANCHORS Location Val Maso, district of Valli del Pasubio (Vicenza, Italy). Landslide reactivated in 2010 due to an extreme rainfall Roto-translational collapse of about 200,000 m3 that threatened the stability of a road and produced a small earth-flow that damaged some houses Eluvial/colluvial deposits and past landslide debris Slope mean inclination angle of about 40° Landslide retrogression by multiple rotational slides, with a sliding surface 20 m deepVAL MASO LANDSLIDESIRIVE® SPECIAL COMPOSITE ANCHORS/SIRIVE® FLOATING ANCHORS Adopting Sirive® Special S60 Composite anchor bars(60 mm diameter bars with 3x0.6” diameter strands and a minimum tensile strength of 2000 kN) anchored to the bedrock, 3 rows of floating anchors spaced 6.0 m and 6.0 m respectively in horizontal and vertical direction were built.VAL MASO LANDSLIDESIRIVE® SPECIAL COMPOSITE ANCHORS/SIRIVE® FLOATING ANCHORS Adopting Sirive® Special S60 Composite anchor bars(60 mm diameter bars with 3x0.6” diameter strands and a minimum tensile strength of 2000 kN) anchored to the bedrock, 3 rows of floating anchors spaced 6.0 m and 6.0 m respectively in horizontal and vertical direction were built.VAL MASO LANDSLIDEMONITORING SYSTEM: DISPLACEMENTSLeica TCRA1101Total StationPrecision in distance measurements = ±2 mmTopographical survey: Determine displacements of 10 points selected on the slope and 30 on the plate of each anchor Landslide medium displ. rate = 2.6 cm/year (post) vs 160 cm/year (pre)Anchor medium displ. rate = 1.6 cm/yearVAL MASO LANDSLIDEMONITORING SYSTEM: HEAD FORCEThe load cells indicate a small decrease of the head-forces in time (14.5-18.9%), which may denote a sort of asymptotic adjustment of the soil close to the concrete plates.050100150200250300350400050100150200250Head force [kN]Daily rainfall [mm]Time [month-year]Daily rainfall Load cell #25 (left) Load cell #13 (right)CISCHELE LANDSLIDESIRIVE® SPECIAL COMPOSITE ANCHORS/SIRIVE® FLOATING ANCHORS Cross and longitudinalextent: 120 and 180 m Medium slope gradient: 24° Houses cracked and damagedCISCHELE LANDSLIDESIRIVE® SPECIAL COMPOSITE ANCHORS/SIRIVE® FLOATING ANCHORS Slow-moving translational landslide Displacements are strongly correlated with the change in pore pressure 2 inclinometers: slip surface 18-20 m deep 33 floating anchors (Sirive® Special S76 Composite Anchors), 40 to 50 m long, 3000 kN ultimate tensile strength, 5 m horizontal spacing, frusto-conical concrete plates (1.5 m diameter)CISCHELE LANDSLIDESIRIVE® SPECIAL COMPOSITE ANCHORS/SIRIVE® FLOATING ANCHORSTHANK YOUUniversity of PadovaDepartment of Civil, Environmental and Architectural Engineeringwww.dallagassa.comwww.sirive.itwww.ancoraggioflottantesirive.comDalla Gassa s.r.l.Geotechnical EngineeringCornedo Vicentino (Vicenza, Italy)

Zabezpieczenie osuwisk przy pomocy kotew Sirive® (Landslide protection using Sirive® anchors)

https://www.research.unipd.it/bitstream/11577/3195075/1/%5bAlberto%20Bisson%5d%20Landslide%20protection%20using%20Sirive%20anchors.pdf

Zabezpieczenie osuwisk przy pomocy kotew Sirive\uae (Landslide protection using Sirive\uae anchors)

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Archivio istituzionale della ricerca - Università di Padova