Ground
Engineering
Datasheets
Anchors
Grouting
Minipiles
Soil Nails
Ground
              Anchors




              Technical Data

                     Applications
Typical examples of where...
Ground
                 Anchors




          Further information

               Cementation Skanska
                  Ma...
Ground
  anchors at
Rosyth Royal
   Dockyard



    Technical Data

                   Client
     Ministry of Defence

  ...
Ground
         anchors at
       Rosyth Royal
          Dockyard



          Further information           The platforms...
Grouting                                                                                           Grouting




          ...
Grouting                                                                                                                  ...
Jet Grouting




                Technical Data

                         Application

                        Structural
...
Jet Grouting




          Further information           Ground improvement - Columns are installed         Tunnelling - B...
Teesport Tank
   Af8b Stabilisation




                     Technical data
                                 Client
      ...
Teesport Tank
Af8b Stabilisation




          Further information           Cementation Foundations Skanska (see         ...
Minipiles




               Technical Data

                      Application
 Can be used in most types of soil.

      ...
Minipiles




          Further information           •   Provision of high capacity small
                               ...
Large
         Diameter
        Bored Piles




              Technical Data

                     Application
           ...
Large
            Diameter
           Bored Piles




          Further information

               Cementation Skanska
  ...
Slope
Stabilisation




    Technical Data




                     With a wide range of experience,               Infrast...
Slope
        Stabilisation




          Further information           Excavations                                   In-s...
Soil Nails




               Technical Data

                      Applications
                 Slope stabilisation

   ...
Soil Nails




          Further information           The process is designed to improve the
                            ...
Soil Nails at
            Ebbsfleet




                Technical Data

                               Client
            ...
Cementation Skanska
Maple Cross House
Denham Way
Maple Cross
Rickmansworth
Hertfordshire
WD3 9SW
Tel: 01923 423100
www.ska...
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Ground Engineering Datasheets

  1. 1. Ground Engineering Datasheets Anchors Grouting Minipiles Soil Nails
  2. 2. Ground Anchors Technical Data Applications Typical examples of where ground anchors may be used include: Supports to bored pile walls Stabilising marine structures Cofferdams Anti-flotation for deep structures Tie backs to river and canal walls Dam upgrading Rock face stabilization Strengthening of dock structures Advantages • Cost effective and practical alternative to propping • Provides open excavation – removes obstacles for bottom up construction • Versatile form of earth retention • High loads can be obtained in relatively poor ground Ground anchors can be used for many factory conditions. Various types of anchor are • Can be used in a wide applications in civil engineering and available to suit a particular application. variety of soil conditions building projects in a wide variety of Permanent anchors incorporate full double • Used to install ‘active’ ground conditions. corrosion protection via two concentric forces into structures Cementation Skanska has extensive corrugated UPVC ducts. Depending on the experience in the use of ground anchor design life, temporary anchors may systems and can provide a full in-house incorporate a single duct, or no corrosion service, from design and installation to protection at all. Removable anchors can be testing. used where there are wayleave issues beneath Anchor capacities generally range adjacent properties. from 100kN to over 3,150kN, with Cementation Skanska have a lengths of up to 70m. The capacity comprehensive fleet of ground engineering achievable depends upon the quality of drill rigs ranging in weight from 1.5 to 12.0 the anchored ground and the number of tonnes. Anchor holes can be bored using a tendons used. variety of drilling techniques including rotary, A recent development has been the top-drive rotary percussive, down-the-hole introduction of multistage anchors. These hammer, and augering. The type of drill rig are used to improve efficiency and used will depend on the access, working room achieve high loads in poor ground through and ground conditions. the use of multiple discrete unit bond In difficult ground conditions simultaneous lengths. drilling and casing systems can be employed Tendons can be made of steel bar, wire to temporarily support the boreholes prior to strand or GRP and are fabricated under installation of the anchors. 08/07/08 Rev 1
  3. 3. Ground Anchors Further information Cementation Skanska Maple Cross House Denham Way Maple Cross Rickmansworth Hertfordshire WD3 9SW United Kingdom Tel: +44 (0)1923 423100 Fax: +44 (0)1923 423681 cementation@skanska.co.uk www.skanska.co.uk Offices Head Office +44 (0)1923 423100 North +44 (0)1302 821100 South West, Midlands & Wales +44 (0)1454 453200 Scotland +44 (0)1698 735899 Northern Ireland +44 (0)28 9024 2746 Republic of Ireland +353 (0)1296 0790 When the borehole is complete, the anchor is either lowered into a pre-grouted hole or post-grouted after installation using an integral primary grout tube. When the grout has achieved a compressive strength of 30MPa the anchor is stressed using a portable hydraulic jack and locked off against a head plate in accordance with BS8081. Restressable head blocks with load cells can also be provided for long term monitoring and adjustment if required. † 08/07/08 Rev 1
  4. 4. Ground anchors at Rosyth Royal Dockyard Technical Data Client Ministry of Defence Main contractor Cementation Skanska Skanska Construction Engineer Schal Cementation Skanska together with However, due to the size and complexity of this Skanska Construction were involved in project, Cementation, in ‘partnership’with the design and installation of over 1,200 Dywidag Systems International (DSI), set up a high capacity rock anchors to strengthen dedicated fabrication yard at Cementation’s the entrance lock at the Royal Rosyth plant depot in Bentley Works, Doncaster. Dockyard. Associated civils works were This gave greater control over the programming carried out to replace the quayside subway and manufacture as well as significant cost roofs and side walls. The aim of the savings for the client. project was to bring the lock structure up All anchors incorporated full double corrosion to the required seismic loading standards. protection in accordance with BS 8081. Inclined anchors were installed at five Holes up to 30m deep were bored using six different levels through the dock walls, Casagrande C6 rigs. The holes were along with vertical anchors either side of constructed using down-the-hole hammer air an existing subway at ground level. The flushed drilling techniques. Typical hole sizes working load was generally 2,250kN (15 were 200mm nominal diameter for the 2,250kN no. strands), with a smaller number anchors and 130mm nominal diameter for the of450kN (3 no. strands anchors.) Ground 450kN anchors. anchor tendons would normally be made at an anchor manufacturer’s own facility A vital component of the construction process and transported to site. were the temporary works platforms used to access the holes along the dock walls. These platforms consisted of portal towers supporting Bailey Bridgedecks, allowing up to five different levels to be utilised simultaneously. 11/07/08 Rev 2
  5. 5. Ground anchors at Rosyth Royal Dockyard Further information The platforms were moved by the use of a wide range of mobile cranes. The Cementation Skanska programming involved in moving these Maple Cross House supports whilst maintaining a high level Denham Way Maple Cross of production was key to the success of Rickmansworth the project. Hertfordshire WD3 9SW The vertical anchors were drilled prior to United Kingdom Tel: +44 (0)1923 423100 removal of the subway roof. After Fax: +44 (0)1923 423681 drilling, these were plugged to allow the roof to be removed in advance of the cementation@skanska.co.uk www.skanska.co.uk anchor installation. Offices The anchors were lifted into the boreholes Head Office +44 (0)1923 423100 using mobile cranes. A neat O.P.C grout North +44 (0)1302 821100 was batched on site using high shear The project was completed within the agreed South West, Midlands & Wales +44 (0)1454 453200 colloidal mixer/pump units. The grout was programme and budget, with successful Scotland +44 (0)1698 735899 injected into the base of the bore using an installation and stressing of all of the anchors. Northern Ireland +44 (0)28 9024 2746 integral primary grout tube within the This would not have been possible without the Republic of Ireland +353 (0)1296 0790 anchor body. In accordance with BS8081, close co-operation of all parties on site. the anchors were stressed after the grout strength had reached 30MPa. Access for stressing the dock wall anchors was achieved using a purpose built stressing platform suspended from a dock running rail. Along with other operations on this project extensive craneage was used to move the jacking equipment into position. All stressing was carried out using DSI jacks which incorporated an innovative locking off stool within the jack itself. This enabled test cycles and locking off to be undertaken without jack removal thus allowing a much quicker stressing process. Project logistics were complex and required the interfacing of all operations on site and liaison with other facets of the dockyard activity. This continued throughout the contract, including the docking of a nuclear submarine during a testing programme. 11/07/08 Rev 2
  6. 6. Grouting Grouting Further information Awards Technical Data Cementation Skanska’s proactive approach to Cementation Skanska safety, quality and production has received Techniques Maple Cross House recognition from within the industry in recent Bulk Infill Grouting Denham Way years. Permeation Grouting Maple Cross Compaction Grouting Rickmansworth Specifically, the Company has proven Compensation Grouting Hertfordshire capability to design and carry out complex WD3 9SW geotechnical projects and deliver them on time Applications United Kingdom Bulk Infill Tel: +44 (0)1923 423100 and within budget to their client’s satisfaction. † Old Coal Workings Fax: +44 (0)1923 423681 Void Filling cementation@skanska.co.uk Permeation Grouting www.skanska.co.uk Shafts Tunnels Offices Excavations Head Office +44 (0)1923 423100 Ground Stabilisation North +44 (0)1302 821100 Compaction Grouting South West, Midlands & Wales Underpinning +44 (0)1454 453200 Ground Stabilisation Scotland +44 (0)1698 735899 Northern Ireland +44 (0)28 9024 2746 Compensation Grouting Tunnelling Republic of Ireland +353 (0)1296 0790 Settlement Prevention Advantages Bulk Infill • Economic development of land previously considered unsafe. Permeation Grouting • Ground improvement to ease construction of basements. • Eliminates unwanted ground water. Application of Grouting Techniques Bulk Infill/Ground Stabilisation Cementation Skanska’s grouting Developers now seek to build new projects in techniques can be used to provide a cost areas once deemed uneconomic due to their effective solution to both temporary and poor ground conditions. In order to provide permanent geotechnical problems. Voids, economic foundation solutions, ground soft ground, settlement and water inflow stabilisation has become widely used for are just a few obstacles encountered turning unsuitable soils into useful founding where grouting solutions can be employed strata. The technique is often used in areas to mitigate their effects during which have been heavily mined. Old workings construction. Since the Company was are now in various states of distress and pose a founded in 1920 Cementation Skanska has potential risk of collapse – with or without any played a leading role in the development application of load from the surface. of grouting solutions to stem water flow, Expensive mass blanket treatments may be stabilise soils, improve ground bearing avoided by the effective use of detailed site pressures and negate settlement. investigation and knowledge of the workings. Effective grouting requires an Cementation Skanska can provide a value- understanding of theoretical principles, engineered solution to enable further accurate interpretation of ground development of the site. characteristics, skilled application and careful monitoring. Cementation Skanska Permeation Grouting can draw on a wealth of experience and Basement construction, shaft sinking, dam cut- resources to provide an effective grouting offs and tunnel excavations are all prime solution tailored to the client’s needs. examples where the need for ground water control is necessary. 08/07/08 08/07/08 Rev 1 Rev 1 4
  7. 7. Grouting Grouting Permeation grouting relies upon the liquid most appropriate grout and delivery system. Coefficient of permeability (m/s) grout flowing through the soil, displacing Choice of grout Compensation Grouting -1 -2 water and gases by forcing them out as the 10 10 10-3 10-4 10-5 10-6 10-7 grout steadily advances. The grout must The excavation of tunnels produces settlement Cement be pumped steadily, taking care not to which can propagate to the surface and cause disturb the soil structure. This is a critical structural damage to those structures which lie Grout with filler (PFA/sand) operation and one which needs to be on or near their path. The philosophy of Bentonite (or clay)/cement controlled and monitored appropriately. compensation grouting is to reduce, or even Cementation Skanska has custom prevent settlement by injecting relatively small Grout with improved penetrability made computer-controlled grouting units quantities of grout between the source of the to monitor and control flow and pressure Microfine cements settlement, (the tunnel) and the foundations of during specialist grouting operations. the structures that require protection. Silicate gel (high resistant gel) Specific instructions can be set to control Typically, horizontal arrays of Tube a each injection, and in turn each injection Manchettes are installed over the treatment Silicate gel (low resistant gel) is recorded and downloaded immediately area which allow repeat injections at any one Resins for the engineer to analyse. Grouting location. This allows multiple injections to be demands full application of the made in areas where settlement is predicted or Ground conditions Coarse ground/scree/ Coarse pre-treated alluvial/fine observational method, and electronic data has occurred. coarse alluvial/highly alluvial (sand & gravel, sands, silty management of the grouting data fissured rock sands)/finely fissured rock improves this iterative approach. Cost effective grouting requires comprehensive knowledge of the ground and ground water conditions in order to select the An essential component of compensation grouting is the monitoring of movements. Precise levelling and electrolevel monitoring of the ground and structures overlying the tunnel provide key data to designing the daily grouting instructions. The data is collated and analysed using our award winning software CemSMART (formerly known as Surpoint +). Close coordination and cooperation is essential to the success of the works. Plant and Resources The Company’s plant depot and workshops are centrally located in the UK to provide first class support to sites and projects throughout the UK. Bentley Works is the traditional home of Cementation Skanska and has grown into the premier plant depot within the industry. It houses and maintains the largest fleet of specialist plant in the UK. From the development of the Cementation pump during the early 1920’s to the latest computerised grouting units, Bentley Works. 08/07/08 08/07/08 Rev 1 Rev 1 2 3
  8. 8. Jet Grouting Technical Data Application Structural Ground improvement Basement slabs Excavation support Underpinning Tunnelling Groundwater control Dam cutoffs Contaminated ground Advantages • Vibration free • Applicable to a wide range of ground conditions • Slabs and supporting struts can be formed below the water table and before bulk excavation • Single process allows programme advantages compared to other techniques Jet grouting is a versatile and effective the ground and the placement and mixing of grout • Predictability of in-situ strength technique which can be used across a wide in the soil. This method produces the most and permeability range of ground conditions. It involves the in- homogeneous soil-cement element with the highest situ mixing of soils with cement grout to form strength and the least amount of grout-spoil return, a predetermined strength / permeability matrix. but can cause heave problems in certain ground The inclusions formed by this process may be conditions. used for structural support, or for the control of groundwater. Double system - A two-phase internal system is employed for the separate supply of grout and air Process down to different, concentric nozzles. Grout is used Cementation developed Jet Grouting in the for eroding and mixing with the soil. The air 1960's for ground water control applications in shrouds the grout jet and increases erosion the Middle East and Africa. The process efficiency. The double system is more effective in involves the insertion of a special drilling tool cohesive soils than the single system. However, the to the required depth using a rotary drilling presence of the air reduces the strength of the technique, followed by carefully controlled column as compared to the single system, and the grout injection whilst rotating and air produces greater spoil returns. withdrawing. The column is formed by the action of the high pressure grout eroding the Triple system - Grout, air and water are pumped in-situ ground perpendicular to the angle of through three different lines to the tool. High insertion to a predetermined radius around the velocity coaxial air and water form the erosion tool. The eroded material is mixed with the medium. Grout emerges at a lower velocity from grout to form a soil-grout matrix. separate nozzles below the erosion jet. This The strength and permeability of the somewhat separates the erosion process from the columns can be controlled by the water / grouting process and yields a higher quality cement ratio and the addition of admixtures to inclusion. The triple system is the most effective the grout. The diameter of the columns is system for cohesive soils, and because the grout controlled by the rotation and lift speed of the replaces a substantial portion of the eroded soil, it is drill tool. less likely to cause heaving of the ground. Jet grouting systems are traditionally divided into three categories, depending on the Applications number of injection nozzles and the medium Groundwater control - Often used for the control of used to erode the soil: groundwater around dams or areas of contaminated ground, the jet grouted columns are overlapped to Single system - Grout is pumped down through form a continuous barrier of known thickness. the drilling rods and exits horizontal nozzles in Ground permeabilites can be reduced to the order of 10-9 m/s. 08/07/08 the tool at high velocity. This causes erosion of Rev 1
  9. 9. Jet Grouting Further information Ground improvement - Columns are installed Tunnelling - Break out zones for tunnelling on a regular grid to improved the global machines may be formed using overlapping Cementation Skanska stiffness and bearing capacity of the soil mass. columns adjacent to launching chambers. This Maple Cross House locally stabilises the ground, enabling the tunnelling Denham Way Underpinning - The technique is extensively machine to complete the initial ring construction in Maple Cross used for the improvement of existing shallow conditions of controlled water ingress and ground Rickmansworth Hertfordshire foundations. It is possible to drill through movement. The technique is also used to stabilise WD3 9SW existing footings, forming a new jet grouted tunnel crowns during open face tunnelling methods. United Kingdom column underneath. The small size of the plant Tel: +44 (0)1923 423100 required means that it is ideally suited to Plant Fax: +44 (0)1923 423681 congested city centre locations. Cementation Foundations Skanska's plant depot and cementation@skanska.co.uk workshops are centrally located in the UK and www.skanska.co.uk provide first class support to sites and projects worldwide. Bentley Works is the traditional home Offices Head Office +44 (0)1923 423100 of the Company and has grown into the premier North +44 (0)1302 821100 plant depot within the industry. It houses and maintains the largest fleet of specialist plant in the South West, Midlands & Wales +44 (0)1454 453200 UK. Scotland +44 (0)1698 735899 From the development of the Cementation pump Northern Ireland +44 (0)28 9024 2746 during the early 1920's to the latest computerised grouting units, Bentley Works ensures that contracts Republic of Ireland +353 (0)1296 0790 are carried out with the best plant available. Excavation support - Jet grouting can be used to construct basement slabs and supporting struts for deep excavations. Overlapping columns can be formed below the water table and before bulk excavation minimising access constraints. Primary A typical slab arrangement Secondary 1 2 3 4 5 08/07/08 Rev 1
  10. 10. Teesport Tank Af8b Stabilisation Technical data Client Huntsman Petrochemicals Limited Main Contractor Cementation Foundations Skanska Limited Engineer ABB Eutech Contract Value £0.25m Commencement Date August 2001 Construction Period 10 weeks Site Address Huntsman Petrochemical Teesport The tanks were constructed circa 1960 and risk the integrity of containment. However Contact in July 2000 ground settlement was noticed of greater concern was that the settlement Philip Ball in the concrete floor and drainage channel might develop to impair the stability of tank of the containment bund, just to the west of Af8b. In view of the concerns expressed tank Af8b. Precise-level monitoring carried Huntsman approached specialist contractors out revealed that further settlement was including Cementation Foundations continuing to occur reaching a maximum of Skanska to design and price ground 46mm by mid-February 2001. stabilisation schemes with the objective of Investigations conducted by Huntsman achieving long term stability of tank Af8b and their consultants ABB Eutech revealed and the containment bund by grouting voids that the settlement appeared to be the result in the rubble fill. Included in the contract of movements within brick and concrete would also be the repair/replacement of the rubbble used to infill a large hole in the damaged concrete elements of the bund to ground which existed some time prior to the achieve integrity of containment. construction of the tanks. The hole was It was not considered necessary or present within the approximately 6m thick economic to grout the rubble fill over the layer of generally slag fill, derived from the whole of it’s plan area and the specialist nearby steel works, which had been used to contractors were invited to propose means reclaim the site in the early 20th century. of limiting the spread of grout within the The hole itself was believed possibly to rubble fill while still attempting to have been created by a bomb dropped on adequately fill the voids present within the the area during the Second World War. The rubble. Further requirements were that the hole was believed to have been back-filled spread of grout within the surrounding with materials arising from the demolition general slag fill should also be limited and of nearby buildings in 1948. that the cost of the project should be The settlements experienced appeared to minimised. be limited to the concrete bund but put at The successful design prepared by 08/70/08 Rev 1
  11. 11. Teesport Tank Af8b Stabilisation Further information Cementation Foundations Skanska (see assess the effectiveness of the grouting as inset picture) was based on the construction work proceeded. Test holes were also Cementation Foundations Skanska PO Box 293 of a grout curtain around the treatment area, successfully drilled and grouted. Bentley Works The grouting works were completed in where it was practical to do so, in order to Pipering Lane Doncaster minimise the spread of grout beyond the November 2001 ahead of programme and South Yorkshire DN5 9RX designated treatment areas, followed by within the budgets set. This permitted the Tel: 01302 820888 bulk infill grouting to minimise the removal of the previously distressed areas Fax: 01302 793203 subsequent grout takes during tube-a- of concrete slab and reconstruction, along cementations@skanska.co.uk manchette (TaM) grouting conducted in with additional works instructed during the www.skanska.co.uk grout holes raked directly beneath the tank. course of the contract, to be completed Offices The drilling of the grout injection holes within the 14 week tender programme. Head Office +44 (0)1923 423100 and the installation of the TaMs were In August 2001 Cementation North +44 (0)1302 821100 carried out using a Casagrande C6 drilling Foundations Skanska were awarded a South West, Midlands & Wales +44 (0)1454 453200 rig employing rotary and rotary percussive ground stabilisation contract by Huntsman Scotland +44 (0)1698 735899 water flush open hole and cased drilling Petrochemicals Limited at their Teesport Northern Ireland +44 (0)28 9024 2746 techniques. The grout curtain construction Storage Site. This Storage Site is situated Republic of Ireland +353 (0)1296 0790 and bulk grouting works were completed within the extensive Teesport Docks using one of Cementation’s modular bulk complex on the south bank of the River grouting stations and the TaM grouting Tees near Middlesborough, Cleveland. using one of the Company's containerised Within the site are two large hydrocarbon TaM grouting units. Throughout the storage tanks used for storing cyclohexane. grouting the injection pressures and Each tank is approximately 24.6m in volumes were carefully controlled to diameter and 14.4m high with a storage 3 minimise unnecessary grout travel, grout capacity of approximately 6,00 m per tank. wastage and possible damage to the tank, Each of the tanks is surrounded by, and bund or other facilities structures. contained within, a reinforced concrete Before, during and after the drilling and bund with the bund wall approximately grouting works a network of precise level 1.5m high. points and electrolevel beams installed in conjunction with Cementation's Field Data Acquisition Department (FDAD) were also directly and remotely monitored to ensure that distress was not caused to the structures. Altogether over 1200 tonnes of PFA, cement, sand and bentonite were injected during a nine week site works period in order to stabilise the designated areas. As work proceeded the respective grout takes of the primary, secondary and tertiary holes and the phases of TaM injections were monitored and compared to 08/70/08 Rev 1 2
  12. 12. Minipiles Technical Data Application Can be used in most types of soil. Ideal for underpinning or strengthening of existing structures, internally and externally. Used to construct retaining walls, high capacity small diameter piles, slope stabilization, high capacity small diameter tension piles. Advantages • Can work within low headroom in restricted working conditions • Virtually vibration free • Ability to bore through masonry or concrete foundations • Permanent liners can be incorporated as steel reinforcement or through very soft strata Cementation Skanska is one of the world leaders in piling and ground engineering. Since it was founded in 1920 the company has continually pioneered the research, development and implementation of numerous geotechnical solutions. One of these techniques is the grouted minipile which has been used successfully for over 25 years. Cementation Skanska offers a full in- house service, from advice through to detailed design and construction of complex foundation packages. Mini piling can also be used in conjunction with many of our other processes. Process A mini pile generally has a diameter of between 100 and 450mm and can extend to depths of over 50m. Either a reinforcing cage, circular hollow section or a centralised re-bar may be used. The Company can offer high capacity mini piles with SWLs of up to 1,200 kN. Some typical situations where mini piles may be used include: 02/07/08 Rev 2
  13. 13. Minipiles Further information • Provision of high capacity small diameter piles. Cementation Skanska • Underpinning or strengthening of Maple Cross House existing structures both externally Denham Way Maple Cross and/or internally. Rickmansworth • Slope stabilisation works. Hertfordshire • Construction of propped or WD3 9SW United Kingdom unpropped retaining walls. Tel: +44 (0)1923 423100 • To resist hydrostatic uplift pressures. Fax: +44 (0)1923 423681 cementation@skanska.co.uk www.skanska.co.uk Offices Head Office +44 (0)1923 423100 North +44 (0)1302 821100 • Construction within restricted working South West, Midlands & Wales areas and/or low headroom. +44 (0)1454 453200 • Working within existing premises with Scotland +44 (0)1698 735899 minimal disruption to other operations. Northern Ireland +44 (0)28 9024 2746 • Low vibration. Republic of Ireland +353 (0)1296 0790 • Remote power packs can be used to further reduce noise and fumes within enclosed areas. • Permanent liners can be incorporated through very soft ground conditions. † Equipment Cementation Skanska has a fleet of mini pile drill rigs ranging in size from 1.5 to 12 tonnes. This plant is extremely versatile and the smaller rigs can travel through internal doorways. Piles may be vertical or raked and can also be pressure grouted for increased capacity if required. Drilling techniques include case and auger, rotary duplex and top or bottom driven rotary percussive. Some advantages of the grouted mini pile are: • Ability to bore through variable and difficult ground conditions. 02/07/08 Rev 2
  14. 14. Large Diameter Bored Piles Technical Data Application Can be used in a wide range of strata. Where non-cohesive or water bearing soils exist temporary casings and/or bentonite or polymer suspension can be used to progress the bores. Diameters range from 600mm to 3000mm with pile depths up to 70 metres and maximum working loads of 20,000kN for straight-shafted piles or 30,000kN for under-reamed piles. Advantages • High load capacity • Can be used with CEMLOC® to plunge structural steel columns • In stiff clays under-reamed bases can be formed to increase pile capacity • Depending on ground conditions, pile concrete can be terminated below piling platform level. Patents UK Serial No. 2138033 Class 7, 37 UK Patent No. 2373801 US Patent No. 6739412 UK Patent No. 2362665 Trade Mark Cementation Skanska has a wide range of can impart a vertical load on to the kelly bar to CEMLOC® piling rigs within the plant fleet, including improve production in difficult strata. crane-based units, and all-hydraulic In addition to installing vertical piles, rigs purpose-built mast machines. Both are can install raking piles, up to 1:4 rake, without suitable for the construction of large modification. diameter cast-in-situ piles. Mast machines are self-erecting. Depths Establishment time on site is shorter than Kelly bars can be of single or telescopic for crane-mounts and for contracts with construction. Standard triple telescopic kelly small sites and/or few piles, this can be an bars allow for depths of up to 55m. advantage. The crane-mounts are more Exceptionally, when required, extended triple suitable for the larger diameter and deeper telescopic kelly bars can reach to 70m below pile range. ground. All of the rigs are fitted with a rotary boring unit which operates a kelly bar. Boring Tools The boring tools are fitted to the kelly bar. Boring tools are available to cope with This equipment has been used to construct different strata. The range includes general large diameter piles in a wide range of purpose augers, rock augers, boring bucket and strata, including very soft silty clays, non- coring barrels amongst others. cohesive soils and weak rocks. The rigs 02/07/08 Rev 2
  15. 15. Large Diameter Bored Piles Further information Cementation Skanska Maple Cross House Denham Way Maple Cross Rickmansworth Hertfordshire WD3 9SW United Kingdom Tel: +44 (0)1923 423100 Fax: +44 (0)1923 423681 cementation@skanska.co.uk www.skanska.co.uk Offices Head Office +44 (0)1923 423100 North +44 (0)1302 821100 South West, Midlands & Wales +44 (0)1454 453200 Scotland +44 (0)1698 735899 Northern Ireland +44 (0)28 9024 2746 Republic of Ireland +353 (0)1296 0790 Standard sizes of boring tools range from In both situations it is often practical to 600mm to 1800mm in increments of terminate the concrete at a low level. This is 150mm, and thereafter in increments of typically used for top-down construction of 300mm up to 3000mm. deep basements. In this situation it is possible In suitable strata it is possible to for a steel column to be plunged into the head construct a dry bore; in water-bearing of the concrete. Our unique CEMLOC® strata it is often necessary to progress the equipment can be used to position the columns bore under flooded conditions, i.e water, to structural steel tolerances. bentonite or polymer. Pile Load Bearing Capacity Concrete Depending on ground conditions pile loads of Concrete grades up to 40N/mm2 are 20,000kN or greater can be safely carried on common, and higher grades can be used straight-shafted piles. where necessary. Special tools are available to form enlarged Where the pile bore is dry, a hopper bases or "under-reamed" piles in suitable with a short tube is used to direct the strata, typically stiff clays. Under-ream concrete down the centre of the diameters are usually specified in increments reinforcement. Under flooded conditions a of 150mm, and diameters of 5400mm or full-length tremmie pipe is used. greater can be provided. Piles of 30,000kN capacity have been formed in London clays using under-reamers. † 02/07/08 Rev 2
  16. 16. Slope Stabilisation Technical Data With a wide range of experience, Infrastructure Embankments and expertise and foundation techniques at its Cuttings disposal, Cementation Skanska is able to offer a solution to nearly all slope The constantly increasing demands upon stabilisation problems. railway and highway infrastructure are necessitating renewal and remediation The term "slope stabilisation" is relevant works to both cuttings and embankments. to the stabilisation of both existing slopes Remediation processes implemented by and new excavations, in either natural or Cementation Skanska have comprised man-made ground conditions. both hard (or mechanical) stabilisation solutions, such as bored and mini-pile Examples of situations requiring walls and ground anchors, and soft stabilisation include: solutions such as lime stabilisation, gabions, drainage, mix-in-place grout • infrastructure embankments and logs, reinforced soil and regrading of cuttings slopes in combination with revegetation. • excavations • existing retaining walls • tunnel portals • natural slopes • cliff faces. The range of techniques that can be applied is as necessarily diverse as the range of problems and includes ground anchors, soil nails, minipiles, bored piles, lime stabilisation, drainage, earthworks and vegetation. 08/07/08
  17. 17. Slope Stabilisation Further information Excavations In-situ retaining walls (e.g. reticulated minipiles & contiguous bored piles), soil Cementation Skanska Excavations for new developments often nails and ground anchors can be used to Maple Cross House require support in the temporary stabilise slopes in this situation. Drainage Denham Way condition, before a permanent retaining Maple Cross measures assist with the stabilisation Rickmansworth structure is constructed. Where process by reducing the disturbing forces. Hertfordshire appropriate the temporary support can be WD3 9SW incorporated within the permanent works United Kingdom Cliff Faces Tel: +44 (0)1923 423100 leading to cost savings. Cementation Fax: +44 (0)1923 423681 Skanska can offer a range of methods to There is a significant number of cliff faces support excavations. These include soil in the UK that border on an unstable cementation@skanska.co.uk www.skanska.co.uk nailing, anchoring, mini-piling and condition and their failure could be guniting. Such methods often produce not detrimental or dangerous to adjacent Offices only cost effective solutions but clear and properties. The stabilisation of cliff faces Head Office +44 (0)1923 423100 open excavations. can be effected by a variety of methods; North +44 (0)1302 821100 however, access is usually the prime South West, Midlands & Wales +44 (0)1454 453200 consideration in proposing the most Existing Retaining Walls appropriate method. Scotland +44 (0)1698 735899 Northern Ireland +44 (0)28 9024 2746 Existing retaining walls, which are in an Cementation Skanska Republic of Ireland +353 (0)1296 0790 unstable condition can be stabilised by the use of ground anchors or soil nails, where With an extensive range of foundation ground conditions are appropriate. These techniques and technical support at its methods of renovation are generally less disposal, Cementation Skanska is equally disruptive than demolition and able to tackle minor stabilisation works, or subsequently more cost effective. major design and construct packages, with Cementation Foundations Skanska has the degree of quality, safety and reliability carried out the remediation of several expected of the UK’s leading foundation existing reatining walls ranging in height and ground engineering contractor. from 3m to 6m. Tunnel Portals Access for tunnel headings often require excavation into an existing slope. Where a portal is being constructed in soil it is usually necessary to stabilise the surrounding soil either by soil nailing and/or some form of retaining wall and anchoring. Anchored or reticulated mini pile walls have successfully been used in this situation by Cementation Foundations Skanska for retained heights of up to 15m. Natural Slopes Natural slopes can often creep due to changes in ground water conditions, the existence of residual shear surfaces, or a combination of both. 08/07/08
  18. 18. Soil Nails Technical Data Applications Slope stabilisation Vertical or battered cuttings Embankments Support to existing or new gravity walls Can be used for both permanent and temporary applications Advantages • Cost effective • Quicker than alternative retention methods • Small rigs can achieve access to difficult and tight locations • Working space requirements are less than for normal piling rigs • Excavation and construction of wall progresses concurrently • Provides open excavation • Can be used in a variety of soil conditions Soil nailing forms part of the The nails are installed using a variety of comprehensive range of ground processes, including driving or drilling and engineering processes designed and grouting. Access requirements often dictate the constructed by Cementation Skanska. method and plant used. The most frequently Developed in the late 1960’s, nailing has used method is that of drilling and grouting, as since been widely used throughout the it copes with a large variety of ground world. It is a slope stabilisation process conditions. It also has the advantage of that utilises arrays of fully bonded passive mobilising high bond stresses between the soil ties installed in the ground. These are and nail, and facilitates the installation of usually grouted bars, made from steel, corrosion protection measures. stainless steel or glass fibre. For shallower slopes, vegetation is often The technique can be cost effectively adequate to stabilise the face. As the angle employed to create both temporary and becomes progressively steeper, the use of a permanent cuttings. It can also be used to geogrid in combination with seeded mats or support slopes or to repair slipping ultimately reinforced sprayed concrete is used. embankments and gravity walls. The facing is held in place by plates bolted Soil nails tend to work best when onto the threaded ends of nails. installed in granular materials, but are also Drainage measures are also provided if commonly employed in soft rocks and deemed necessary to maintain long term stiff clays. stability and to reduce the potential for sloughing of the surfaces. 08/07/08 Rev 1
  19. 19. Soil Nails Further information The process is designed to improve the strength and deformation characteristics Cementation Skanska of the existing ground. It is similar to Maple Cross House reinforced fill techniques in that the soil Denham Way nails generate tensile forces in response to Maple Cross Rickmansworth slope deformation. This is in contrast to Hertfordshire ground anchors that are intentionally WD3 9SW stressed to minimise ground deformations. United Kingdom Tel: +44 (0)1923 423100 Soil nails are normally designed to Fax: +44 (0)1923 423681 operate with working loads in the range 25kN to 100kN. cementation@skanska.co.uk www.skanska.co.uk Long term monitoring of full-scale structures has increased Cementation Offices Skanska’s fundamental understanding of Head Office +44 (0)1923 423100 soil nail design. Load testing of soil nails North +44 (0)1302 821100 is often a design requirement and the South West, Midlands & Wales +44 (0)1454 453200 Company has the capability to carry out Scotland +44 (0)1698 735899 both manual and fully automated soil nail Northern Ireland +44 (0)28 9024 2746 pullout tests. † Republic of Ireland +353 (0)1296 0790 08/07/08 Rev 1
  20. 20. Soil Nails at Ebbsfleet Technical Data Client Union Rail Main Contractor Hochtief/Norwest Holst JV Engineer Rail Link Engineering Further information Cementation Skanska Maple Cross House Denham Way Maple Cross Rickmansworth Hertfordshire WD3 9SW United Kingdom Tel: +44 (0)1923 423100 Fax: +44 (0)1923 423681 cementation@skanska.co.uk www.skanska.co.uk Offices Head Office +44 (0)1923 423100 North +44 (0)1302 821100 South West, Midlands & Wales Soil nailing was used at two locations on The second location where soil nails were used +44 (0)1454 453200 the Ebbsfleet project. was at the Pepper Hill junction of the A2 Scotland +44 (0)1698 735899 The first application was to allow where improvement works were carried out for Northern Ireland +44 (0)28 9024 2746 construction of a wing wall to bridge the Highways Agency. Permanent corrosion Republic of Ireland +353 (0)1296 0790 3590. This involved installation of 11m protected nails of 3-6m in length were long fully corrosion protected nails installed through embankment fill and chalk. through rock fill, made ground and chalk The face of the cutting was at 50° to the to form a near vertical triangular shaped vertical and was stabilised using a flexible cut. Sprayed concrete was used to facing (comprising double twist galvanised provide temporary face stability, followed wire mesh). For both sites comprehensive later by permanent cast-in-situ concrete testing was carried out. † wing wall to provide a compatible architectural appearance to other wing walls for the bridge. 08/07/08 Rev 1
  21. 21. Cementation Skanska Maple Cross House Denham Way Maple Cross Rickmansworth Hertfordshire WD3 9SW Tel: 01923 423100 www.skanska.co.uk

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