Chance Technical Design Manual

used in the controlled fills of roadway and railway fills to make improvements to the infrastructure. Helical piles should be capable of penetrating the collapsible soils (such as loess) and poorly cemented granular soils in the southwestern United States. EQUIPMENT Equipment suitability consideration and selection is the do main of the contractor. Certified Chance® Installers are familiar with the various spatial requirements for his equipment and is best able to determine the type of mounted or portable equip ment they can utilize to do the work. The designer may contact the local Chance® Distributor or certified installer for guidance on this matter. A wide variety of equipment can be utilized for projects based on such considerations as interior vs. exterior construction and headroom. Mini-excavators have been used indoors to install helical piles. CONTRACTORS Certified Chance® Installers are available in nearly all areas of North America. These installers should be experienced in the type of work specified. A current project list should be submit ted as evidence of experience. CODES Building codes may have restrictions regarding the founda tion type. Generally, Chance® helical piles and Atlas Resistance® piers fall under the category of deep foundations, such as driven piles or drilled piers. The underpinning shaft series of Chance® helical piles and Atlas Resistance® Models AP 2-3500.165 and AP-2-3500.165 (M) have been evaluated to show compliance with past and also the latest revisions of the International Building Code (IBC). Chance® Type SS5, SS175, RS2875.203, RS2875.276, RS3500.300, SS175/RS3500 Combo, and RS4500.377 helical piles and bracket assemblies have been evaluated per International Code Council Evaluation Services (ICC-ES) Acceptance Criteria AC358 for Helical Systems and Devices. In Canada, CCMC Report 13193-R shows compliance with the latest revisions of the Canadian Building Code (CBC). The current evaluation reports can all be found at www.chancefoundationsolutions.com.

Working tension loads are typically 100 kip or less. The soil is generally the limiting factor as the number and size of he lical piles/anchors can be varied to suit the application. The designer should determine the shaft series of products to use from the information provided in Section 7 – Product Drawings and Ratings. Atlas Resistance® piers have been used in compression to working (design loads) of 70 kip+. The soil conditions, weight of the existing foundation, and type of foundation are gen erally the limiting factors when determining the number and size of Atlas Resistance piers to use in a given application. The designer should determine the shaft series of products to use from the information provided in Section 7 - Product Drawings and Ratings. SOILS Soil may be defined for engineering purposes as the uncon solidated material in the upper mantle of the earth. Soil is vari able by the nature of its weathering and/or deposition. The more accurately one can define the soil at a particular site; the better one can predict the behavior of any deep foundation, such as a Chance® helical pile, Helical Pulldown® Micropile or Atlas Resistance® pier. In the absence of sufficient soil data, assumptions can be made by the designer. The field engineer or responsible person needs to be prepared to make changes in the field based on the soil conditions encountered during construction. As noted earlier, Atlas Resistance® piers will provide the foun dation underpinning support in an end-bearing mode provided N-values are generally above 30 to 35 in cohesionless (sands and gravels) soils and above 35 to 40 in cohesive clay soils. Chance® helical piles can be installed into residual soil and vir gin or undisturbed soils other than rock, herein defined as hav ing a SPT “N-value” less than 80 to 100 blows per foot per ASTM D1586. This implies that the correct shaft series of helical piles must be chosen to match to the soil density. For example, a standard 1-1/2” shaft, Type SS helical pile with a total helix area of 1 square foot may require so much installing torque that it may have difficulty penetrating into the bearing stratum without exceeding the torsional strength of the shaft. Water-deposited soil, marine, riverene (terraces or delta) and lacustrine soil have a high degree of variability. They may be highly sensitive and may regain strength with time. In these conditions, it is good practice to extend helical piles and resis tance piers deeper into more suitable bearing soil. Very soft or very loose natural, virgin or undisturbed soils over lying a very dense soil layer, such as unweathered rock, present an ideal situation for the installation of Atlas Resistance® piers. Similar soil profiles could present a challenge to the installa tion of helical piles depending on the weathered nature of the underlying rock. The helices may not develop enough down ward thrust in upper soils to penetrate into the hard underlying material. Down pressure is often applied to the shaft to assist in penetration of the helices into the hard underlying material. The use of helical piles/anchors in controlled or engineered fill is another good application. For example, helical tiebacks are

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