Secant Pile Wall Installation Method: When properly constructed, secant pile wall offer soil support plus full water tightness. They are applied in liquid state, forming a high strength foam on contact that rapidly cures to give a reliable and robust surface. There are three distinct bored pile wall options in current use: Contiguous wall, Secant wall and tangent wall. unreinforced weak concrete mix constructed to a depth just below Contiguous Pile Wall Contiguous piles are suitable where the groundwater table is below excavation level. Piling. When properly constructed, secant pile wall offer soil support plus full water tightness. bored pile method, except the gap between the primary piles is According to the pile layout the pile wall is divided into a secant/tangent or contiguous pile wall.. Cantilever pile wall The use The use of low-cost augers and, more particularly, Contiguous Flight Auger (CFA) rigs to drill Pile walls can be either closely-spaced contiguous piles walls or secant pile walls. The secant piles are reinforced with either steel rebar or with steel beams and are constructed by augering. 5. A sequence of secondary piles They may be constructed either by using segmental temporary casing and conventional heavy duty rotary drilling tools or by continuous flight auger (CFA) techniques. Of all the methods of piling it is typically the most cost effective and least time consuming. Construction, Use, Advantages and Disadvantages. Secant Pile Walls are formed by constructing intersecting reinforced concrete piles. The wall consists of individual piles typically installed at centres 150mm greater than their diameter. In the final basement wall condition, the contiguous piles would normally be shotcreted to prevent any loss of retained soil between the piles over the life of the structure. A reinforced concrete guide wall is constructed at piling platform level to aid positional and verticality tolerances for the auger / casing. installed at pile centres of between 500 and 1000mm respectively Age (days) Rig Weight (T) Power (KW) Torque (KNm) Max. The piles may be constructed so that they virtually touch each other (contiguous). Underpinning. CFA piles; Driven precast piles; Bored piles; Minipiles; Restricted access piles; Pali Radice; Driven cast in-situ piles; Helical piles; Earth retention. Wooden piles are made from the trunks of tall trees. Alternatively (secant piles) every other pile may be constructed, with their centres less than two diameters apart. The diameter of each pile in a contiguous piled wall is usually not less than 300mm diameter. Bored cast in-situ piles are often used as an efficient and However, while they avoid excessive excavation and assist in the control of ground movement, the risk of groundwater ingress between the piles can be significant. A secant pile wall consists of overlapping (secant) piles to form structural or cutoff walls and achieve the required water tightness. They’re normally the fastest and most efficient piled wall option. sprayed concrete or cladding. The most common use of sprayed concrete in the civil engineering industry is the facing of piled walls. substructures in close proximity to existing structures requiring current use: Contiguous wall, Secant wall and tangent wall. The commonly used retaining walls include soldier piles and lagging, sheet piles (commonly Z and U sections), diaphragm walls (commonly 0.6 to 1.0 m thick), contiguous bored piles (commonly 0.8 to 1.0 m) and secant piles. 19 The secant piles wall consists of two types of piles: 20 Piling - Contiguous, Interlocking and Secant Bored cast in-situ piles are often used as an efficient and cost effective means of constructing temporary or permanent retaining walls. Secant pile walls are formed by constructing intersecting reinforced concrete piles. Contiguous pile walls; King post wall; Secant pile walls; Anchors - single bond length; SBMA ; Soil nails; Slurry cut-off walls; … cost effective means of constructing temporary or permanent retaining secant pile wall (Hard / soft) This wall is used where considerations of retained height and water retention are less critical. Filling of pile … The piles may be constructed so that they virtually touch each other (contiguous). Of all the methods of piling it is typically the most cost effective and least time consuming. The system eliminates the need to use support fluid or casings in cohesive soils, non-cohesive or water bearing soils. the depth of final excavation. Secant piles are reinforced with either steel rebar or steel beams. It is a vibration-free and low noise drilling procedure used for installation of single piles, as well as contiguous, tangential or secant pile walls. Typically there are three types of bored pile in current use. Cast the male piles with full reinforcement cage (and withdraw the casing, if used) to allow the concrete in the male piles to flow and bond with the existing concrete of the previously cast female piles. Secant Wall Piling – hard/soft or hard/firm. The piles are reinforced with either steel rebar or with steel beams and are constructed by drilling under mud. Secant pile walls are constructed when resistance to groundwater is required using the CFA technique or the cased CFA technology. From soil mixing to drilled shafts, Keller draws on its complete suite of techniques to optimize the design and construction of these walls. Alternatively (secant piles) every other pile may be constructed, with their centres less than two diameters apart. The wall consists of individual piles typically installed at centres 150mm greater than their diameter. Pile Diameter (m) Max.Pile A secant pile wall when completed is a cost effective alternative Secant pile walls rely on the interlocking or overlapping arrangement of piles to achieve a higher level of soil retention than contiguous or soldier pile systems. Performance advantages: A contiguous bored pile wall is formed by installing closely spaced bored piles, with a gap between adjacent piles of typically 75 to 150mm. thereby leaving gaps between the piles between 15 and 100mm. Secant piling is when there is no gap between piles as a wall is made of interlocking bored piles. Primary piles are installed first with secondary piles constructed in between primary piles once the latter gain sufficient strength. • Contiguous pile wall • Secant pile wall – hard/soft or hard/firm • Secant pile wall – hard/hard The choice of system depends on a number of factors. The drainage is usually made of perfored plastic tubes. Typically used in the construction of new build basements, Contiguous pile walls retained by anchors or strutting systems are often supported by a waler beam to distribute the loads (and prevent anchors/struts from punching through the infill) and as a mitigation measure for the unlikely event of an anchor/strut not carrying the load. This form of construction ensures The piles may be constructed so that they virtually touch each other (contiguous). The piles may be constructed so that they virtually touch each other (contiguous). This type of construction is in many ways similar to the contiguous Secant pile walls are formed by constructing reinforced concrete piles that interlock, and are often used as a cost-effective solution when short-term water retention is required. Soldier Pile Walls With soldier pile walls, the piles are fitted wider apart (up to 5 - 8 pile diameters), with the soil between piles subsequently retained. Secant pile walls retained by anchors or strutting system are often supported by a waler beam to distribute the loads (prevent punching of anchor/strut through the pile) and as a mitigation measure for the unlikely event of an anchor/strut not carrying the load. The process can offer a number of facing options depending on the requirement of the lining wall. fashion to the primary pile. The options include: 1. Alternatively (secant piles) every other pile may be constructed, with their centres less than two diameters apart. Depending on geotechnical characteristics of the location and project requirements, we differentiate several types of pile wall. rotary cutting heads. A series of adjacent piles constructed to form an earth retaining structure as a cantilever or a propped cantilever wall. Piling Contractors. Contiguous piles are an efficient and cost-effective means of creating retaining structures. The gaps between the piles can be grouted to form a watertight retaining wall. First, the primary piles are cast with a weaker, unreinforced concrete that can be cut in the second stage, when the secondary piles are bored. According to the type of resistance, the pile wall is divided into a cantilever or a supported structure. Secant Piling; Contiguous Piling; Sheet Piling; Silent and Vibrationless Sheet Piling; King Post Walls; Load Bearing Piles; Close Proximity Piling; Vibro Displacement Piling; Basements; Sheet Pile Sales; Steelwork. In contiguous pile walls, the axial distance of piles is bigger than their diameter. of concrete similar to the primary pile and reinforced in a similar If the piles are constructed so that they are touching they are called contiguous piles, and they can then be grouted to form a watertight wall. Pile overlap is typically in the order of 3 inches (8 cm). Closely spaced bored piles can be used to form a retaining wall, perhaps for the construction of a deep basement or a cut and cover tunnel. Bored cast in-situ piles are often used as an efficient and cost effective means of constructing temporary or permanent retaining walls. For a contiguous pile wall i.e. Closely spaced bored piles can be used to form a retaining wall, perhaps for the construction of a deep basement or a cut and cover tunnel. filled with a secondary ‘soft pile’ consisting an Because the piles are discreet the retaining function of the wall relies upon the soil between the piles arching. A secant pile wall is a cost effective alternative to diaphragm wall construction. First, the primary piles are cast with a weaker, unreinforced concrete that can be cut in the second stage, when the secondary piles are bored. Secant Piled Retaining Walls The wall consists of bored piles typically installed at centres 150mm greater than their diameter. Contiguous pile wall. are constructed followed by a sequence of primary piles constructed In situ pile retaining walls are very popular due to their availability and practicability. Contiguous pile walls are also suitable for a variety of soils, where groundwater lies below the maximum excavation depth. Pile overlap is typically in the order… The secant piles are reinforced with either steel rebar or with steel beams and are constructed by either drilling under mud or augering. These include soil type, ground water profile, retained heights, available construction time, propping arrangement, cost and design life. The secant piles are reinforced with either steel rebar or with steel beams and are constructed by either drilling under mud or augering. avoids excessive excavation and assists in the control of ground The piles may be constructed so that they virtually touch each other (contiguous). secant piles generally comprises a heavy duty CFA auger with Diameter and spacing of the piles The gaps between the piles can be grouted to form a watertight retaining wall. The wall is formed by constructing alternating primary (female) and secondary (male) piles where the secondary piles partially cut into either side of the primary piles in order to form a continuous impervious structure. Primary piles are installed first with secondary (male) piles constructed in between primary (female) piles once the latter gain sufficient strength. To aid construction, the first sets of piles may be cast with a lower grade of concrete. Secant Pile Walls –Soft mix BNZ Auckland •Strength of “soft” mix –Fit for purpose •Infill between piles •Unreinforced •Strength & Batching variance of small quantities 0 2 … The wall consists of bored piles typically installed at centres 150mm greater than their diameter. When waterproofing contiguous or secant piling, the Vandex Super waterproofing layer is typically sandwiched between a layer of shotcrete and a poured concrete internal wall (see Figure 2) This method of waterproofing is dependent on the strength of the underlying piles and the tolerances between them than the Oldroyd method (see Figure 1 ). Continuous Flight Auger (CFA) piles offer an economic, quick, low noise and vibration solution to constructing retaining walls or bearing piles for medium to highly loaded structures. The wall consists of discrete piles typically installed at centres 150mm greater than their diameter, leaving gaps … Contiguous Piled Walls are used where the groundwater table is below the desired excavation level and can be installed using rotary bored or CFA techniques. Contiguous piles are suitable where the groundwater table is below excavation level. The procedure for constructing secant piles is similar to interlocking Primary piles are installed first with secondary (male) piles constructed in between primary (female) piles once the latter gain sufficient strength. The equipment used to construct The design can incorporate steel bar or beams for reinforcement and anchors can provide additional lateral support, if needed. As the piles interlock, this form of construction leads to a more efficient form of structure. Piling. A method of drainage will generally be required between the piles and any inner wall. Testing a secant pile wall A secant pile wall (Figure 1) consists of two series of piles: primary and secondary. The CSP method can be used to construct deep secant or contiguous piled walls depending on the actual ground conditions and water table. depth of excavation. Concrete Bookshop - Members receive 40% discount on Concrete Society publications. Primary (female) piles are constructed first using a ‘firm’ concrete / bentonite (commonly 10N/mm2). By providing specialist underpinning we can repair subsiding or sinking buildings. Piling - Contiguous, Interlocking and Secant . Contiguous pile wall is executed with a spacing between piles. The guide ensures that piles are accurately located to achieve an interlock (or ‘secant’) cut into the adjacent pile. Secant Pile Walls –Soft mix BNZ Auckland •Strength of “soft” mix –Fit for purpose •Infill between piles •Unreinforced •Strength & Batching variance of small quantities 0 2 4 6 8 10 12 0 7 14 21 28 35 42 49 56 63. There is, however, a relatively large increase in cost for this system in comparison with concrete soldier piles. Contiguous piles are particularly suited to sites with restricted access. When waterproofing contiguous or secant piling, the Vandex Super waterproofing layer is typically sandwiched between a layer of shotcrete and a poured concrete internal wall (see Figure 2) This method of waterproofing is dependent on the strength of the underlying piles and the tolerances between them than the Oldroyd method (see Figure 1 ). Sheet piled walls are a wall made of sheet piles usually using a U or Z profile and interlocking clutches that minimise water flow through them. Contiguous Bored Piles/Secant Piles Closely spaced bored piles can be used to form a retaining wall, perhaps for the construction of a deep basement or a cut and cover tunnel. The piles may be constructed so that they virtually touch each ot (contiguous). The gaps between the piles can be grouted to form a watertight retaining wall. It is normally the most economic and rapid option. A contiguous pile wall is simply a row of concrete soldier piles installed so that each pile is in contact, or near contact, with piles on either side of it. Piles can be … Secant pile walls are formed by constructing intersecting circular reinforced concrete piles. A contiguous bored pile wall is formed by constructing a series of individual vertical RC piles. to the full design depth, cutting into the secondary piles and The design can incorporate steel bar or beams for reinforcement and anchors can provide additional lateral support, if needed. Contiguous pile walls are cons tructed with small gaps betw een adjacent piles. Typically, primary (female) piles are cast in situ, leaving space in between them. For excavations in soft soils, rigid walls such as diaphragm walls and contiguous bored pile walls are commonly used as they are more effective than the more flexible walls such as sheet pile walls, in limiting soil movements to an acceptable level. If it is necessary, the shotcrete layer can be installed on the pile wall to stabilize the material. Contiguous bored pile wall (gap between piles) – no water seal / permanent works Secant piled walls – this includes hard/firm and hard/hard secant pile walls, – watertight / temporary works In order to ensure the high verticality tolerances and maximum water tightness; we recommend that secant walls be constructed through concrete guide walls cast ahead of piling works. Contiguous pile walls are constructed with small gaps between adjacent piles. S = Pile Spacing (c/c) D = Pile Diameter piles, save that the secondary pile is not soft but constructed Because of the form of construction, the exposed piles will be fairly rough in appearance. Pile overlap is typically in the order of 8 cm. CFA piles; Driven precast piles; Bored piles; Minipiles; Restricted access piles; Pali Radice; Driven cast in-situ piles; Helical piles; Earth retention. This space must be correctly drained, so that rainwater does not stay behind the concrete. Contiguous Pile Walls Used in locations where water retention is not a consideration and soils are cohesive, contiguous bored male piles through the previously cast female piles with the required design intersect utilising the casing to cut the required secant 4. Contiguous Pile Wall. This is common when constructing basements, underpasses or cut and cover tunnels. Contiguous Piled Walls are used where the groundwater table is below the desired excavation level and can be installed using rotary bored or CFA techniques. to diaphragm wall construction. Our specialist piling contractors offer comprehensive building foundation packages, installing piles for both commercial and domestic clients across the midlands and southern England. In-fill piles are then bored, cutting into the adjacent piles to form a continuous structure. Both types of walls are a type of retaining wall used when you want to go below ground. Thus, in most cases, an inner wall, which may or may not be structural, will be built or some decorative surface applied, e.g. The gaps between the piles can be grouted to form a watertight retaining wall. Contiguous bored pile walls consist of a line of individual piles positioned at close centres and are formed by conventional continuous flight auger or rotary auger bored pile techniques. The gaps between the piles can be grouted to form a watertight retaining wall. subsoils and where ground water levels are below the eventual The space between them is usually filled with shotcrete and reinforcing mesh. 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