b'Effects of Water Table Fluctuations and Freeze Thaw CycleWhen designing helical anchors, the amount of uppermost plate.Inmostcasesthisisusuallywaterpresentinthesoilatthetimeof means installing the helical plates three to fourinstallation, and possible moisture changes in the feet below the lowest expected frost depth.Thefuture,mustbeconsidered.Iftheanchoris reasoning here is that when the soil thaws andinstalled near the water table, the capacity of the theicechangestowater,thesoilcanbecomeanchorcandramaticallychangewiththe saturated.Fromthediscussionaboveaboutchanging level of the water table. installations made near the water table, a similarCohesionless soil is buoyed by the water when situationexistswiththawingfrost.Loadthesoilaroundthehelicalpileoranchor capacitycouldreducebecausesaturatedsoilbecomessaturated.Thisbuoyancyofthesoil cannot support as much load as damp to dry soil.particles in the soil reduces the load capacity of Claysoilisespeciallyvulnerableandcantheanchor.Adifferentsituationexistsifthe becomeplasticwhen saturated.Asaturatedanchorisjustbelowthewatertableanddry cohesivesoilmightsimplyflowaroundtheconditions cause the water table to drop.As the helical plates causing anchor creep or failure. Inwater drains from between the soil particles, the addition, when the plates are terminated withinsoilaroundthehelicalplatescouldbeginto the freeze-thaw zone, freezing water within theconsolidate.This soil consolidation may cause pores of the soil can lead to upward pressure onthe anchor to creep and require adjustment. the helical plates resulting in movement and/orloss of strength.It is also important to know the maximum frost Monitoringtheinstallationtorsionontheshaftdepth along with the range of depth for the water can predict the performance of the anchor at thetable at the job site to insure a solid and stable timeofinstallation,butchangesinthesoilinstallation. Anchors should always be installed moisturecanaffectthe productslongtermbelowthelowestrecordedfrostdepthplusa holding ability.minimumdepthofthreediametersoftheBudgetary Capacity Estimates by Quick-Solve Design MethodMany installers and engineers are familiar with classification. The graphs are not intended tothe SoilClassificationTablethatother be a substitute for engineering judgement andmanufacturersuseforbudgetaryhelicalanchor design calculations presented earlier that relydesigns.Thistableclassifiessoilintoeight upon specific soil data relative to the project.soil groups ranging from solid rock down to very Table9andGraphs2through5representsoftclays,organicsandpeat.TheseSoil generaltrendsofcapacitythroughdifferentClassificationTablesare recommendedtobe homogeneoussoilclassifications.Thegraphsused only forreferenceto roughly estimate are based upon conservative estimates.expected pile capacities on the graphs or tables.Table 9 below reproduces the Soil Classification Graphs2through5representtheultimateTable showingtheclassificationlevelsoffered capacity of the helical plate configuration in thebyothermanufacturersalongwithanticipated soil, and one must always apply a suitable factorvaluesforStandardPenetrationTests,N, of safety to the service load before using theselikely to be found within each classification.The tables to insure reliability of any tieback or pileHoldingCapacityGraphs2through5that installation.followweredevelopedtoproviderough In very dense soil or rock stratum when rotationestimates of holding capacities for various sizes of the helical anchor shaft does not advance theandcombinationsofhelicalplatesattachedto productintothesoil,thehelicalplatesarenotTorque Anchor shafts when installed into these abletofullyembedandcannotachievethesoil classifications. capacitylevelpredictedbyTerzaghisbearingItmustbeclearlyunderstoodthatGraphs2 capacityformula(Equation1).The soilthrough 5 are provided to offer general estimated classificationgraphs disregard Class0throughClass 2 because these soils are usually too denseload capacities for piles or anchor configuration for the Torque Anchors to advance without pre-installed into a soil that fits within a certain soil drilling,ECP Helical Torque Anchors Technical Service Manual2021 Earth Contact Products, L.L.C.2021-09 Chapter 1 - Page 22 All rights reserve'