# Field Pull-Out Tests of Percussion Driven Earth Anchors (PDEAs)
## 1 Introduction  
State Departments of Transportation in the USA, including TxDOT, continuously battle with unforeseen slope failures associated with their infrastructure. Slopes are generally used as a part of roadside safety elements along roadways, bridge abutments, and channel banks. Several methods have been used to treat slopes associated with critical structures to minimize slope stability failures that may cause a safety hazard to the traveling public. TxDOT [1] recommends upper limits on the plasticity index (PI) for exposed side slopes based on different slope conditions to reduce the probability of slides. The agency does not recommend exposed slopes of less than 2.5 to 1. Bridge abutment slopes have been historically treated by concrete riprap. Rock irprap and gabion mattresses have been prevalent slope treatments for channel bank slopes. Rock irprap and gabion mattresses have successfully been used on slopes of 3:1 and flatter. Soil anchors and nails have been widely used to achieve stability of critical steep slopes by providing counter forces to the driving forces that tend to destabilize the slope mass. Channel slopes stabilized by soil anchors have the advantage of maintaining channel flow capability compared to retaining walls such as gabion walls. The uplift capacity of a vertical buried anchor, also known as the breakout factor, typically comprises the weight of soil within the failure zone and frictional and/or cohesive resistance along the realized failure surface. The required uplift capacity of these systemscan be enhanced by increasing the size and embedment depth of the anchor or improving backfill strength and density [2; 3; 4; 5; 6; 7; 8]. According to [PERSON] [9], an anchor design depends upon a dimensionless critical depth value of H/B, where H is the depth of the anchor and B is the anchor base width or diameter, depending on the type of anchor. Critical depth defines the depth at which an anchor is classified as deep or shallow. Extensive research has been performed to improve the assessment of anchor uplift behavior within unreinforced soil, comprising experimental, analytical, and numerical studies. Early research on anchor uplift capacity was conducted under 1 g conditions in stabilizing transmission towers. It was primarily limited to scaled laboratory experiments to demonstrate the effects of shape, embedment, soil conditions, and soil types on anchor resistance [10; 11; 12; 13; 14; 15]. Centrifuge-based laboratory experiments have been employed to capture better realistic, scaled gravitational conditions assessing uplift capacity [16; 17; 18]. Theoretical uplift solutions have been developed by using cavity expansion theory [19], limit equilibrium theory [20; 21; 22; 23], reverse hopper theory [24], and elastoplastic continuum analyses [18; 25]. Three different experimental studies conducted on anchors' performance by [PERSON] [26] produced three critical depths of 6, 3, and 1.5, respectively. [PERSON] and [PERSON] [27] conducted experiments on sands with circular anchors and inferred that anchors with H/B of above 6 are deep. They found the critical depth based on the shape of the failure surface suggested by Balla [28]. They observed that the pull-out strength of anchors below the critical depth of 6 was very close to the ones calculated by the Balla equation. They also observed, for shallow anchors with a H/B value less than 6, that an upheaval of the ground surface above the anchor was preceded by a curvilinear failure plane. For deep anchors with H/B values over 6, [PERSON] and [PERSON] observed neither a curvilinear failure pattern nor upheaval of the ground surface until the anchors were pulled far enough [9]. [PERSON] et al. [29] also looked at the failure modes of the sand soil during pull-outs of plate anchors and found that when anchors are sufficiently deep, i.e., H/B = 8, the soil exhibits local failure and moves clockwise around the anchor.