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20 <br /> For groups of closely spaced piles, the group capacity may be less than the <br /> sum of the individual pile capacities. Group effects, however, are normally <br /> small for piles that are more than three center to center spacings apart. If the <br /> pile centers are less than three pile diameters apart, consideration should be <br /> given to decreasing the pile capacity because of group effects. <br /> Pile Settlements. Assuming that the piles are spaced more than three pile <br /> diameters apart, are driven at least one pile diameter or 2 ft (whichever is <br /> greater) into the sand, and are loaded to load levels less than shown on Plates <br /> 38 through 40, settlements are anticipated to be less than 1/4 of an inch. <br /> Lateral Pile Capacity. The lateral load capacity is dependent upon the <br /> allowable pile head deflection as well as the type and size of pile, the modulus <br /> of elasticity of the pile, and the lateral modulus of elasticity and strength of <br /> the soil. These factors are interrelated. For example, the soil resistance is a <br /> function of the pile size. Also, the allowable lateral loads may be controlled <br /> by the structural properties of the pile. <br /> Recommended design lateral capacity for several pile types are shown in the <br /> following table. <br /> Allowable Lateral Capacity (kips) <br /> Assuming Pile Head Embedded In <br /> Pile Type Silty Sand Glass <br /> 12-in.-sq precast concrete 5 3 <br /> 14-in.-sq precast concrete 8 5 <br /> 12-3/8-in.-diam steel pipe 7 4 <br /> These capacities assume a pile head deflection of 1/4 inch and a pile spacing <br /> that exceeds three pile diameters. The above capacities include a factor of <br /> safety of 2.5.. The lateral capacities for other sized concrete and steel pipe <br /> piles can be scaled in proportion to the pile width or diameter. <br /> Removal and Replacement <br /> Removal of the glass and uncontrolled fill followed by replacement of the <br /> excavated materials with engineered fill is a second option. Because the glass <br /> is locally as deep as 16 ft below the present ground surface, a relatively thick <br /> layer of compacted fill will underlie portions of the site. Because much of the <br /> 1144A/CC-20 ii McClelland <br />