pile driving hammer energy calculation

The successful use of these hammers led to more widespread use, particularly in Europe. 326 0 obj <>/Filter/FlateDecode/ID[<2A84DAB0928AC74EB2312F9B49A745B4><96E3DD0E2FEE8D4D9EA5AB2195EC0CE5>]/Index[312 25]/Info 311 0 R/Length 76/Prev 69020/Root 313 0 R/Size 337/Type/XRef/W[1 2 1]>>stream 867 0 obj <> endobj The helmet is a temporary steel cap placed on top of the pile used to, as much as possible, protect the head during driving. Calculate drivability: this is done by using the wave equation program. GRLWEAP14s user-friendly interface includes more than 1000 preprogrammed hammers, extensive help, and numerous automatic features. of energy as well as many other popular models for more typical piling projects. 0000006496 00000 n H-piles were used as a way to address problems that occurred with the use of I-piles. As a construction method, pile driving has existed since before humankind was literate. In order to maintain a comparable energy rating, the ram was accelerated during its down stroke using active pressure. Each part has a role in transferring energy to the pile which in turn impacts hammer performance. P. ILES . In addition to advances with the piles themselves, the rigs that drove them also evolved. 0000004296 00000 n Already a member? necting the LMI during pile driving. The design chart is given in Fig.1. Vibrating Weight Without Clamp: 3060 kg Helmet Wooden piles would continue to be used until the end of the nineteenth century. Using wave equation analysis, dynamic monitoring of the pile driving process, and static load testing can all assist in achieving these objectives. 0000011989 00000 n The VU-1.6 could drive the same size of pipe to depths up to 30 meters. 2482 0 obj <>stream Forget it. Dynamic Force: 182 tons There are two key reasons for a lower-than-anticipated blow count. Hammer coefficient is given in Table 1. The piles were installed by driving (hammering and vibration) and boring techniques. Evaluate hammer performance and make adjustments, if needed. Higher rate of blows per minute than drop hammers. GRLWEAP Offshore Wave Version includes exclusive features designed for challenging situations (free riding hammers, nonuniform and battered piles) and special analysis options such as fatigue output tables. The impact block separates from the ram within a very short time and the pressure of the combusting air-fuel mixture will cause further separation as the ram is forced upward. In this article we discuss pile driving basics, the common problems encountered, and potential solutions. When the hammer is lifted and thrown down, with some energy lose while driving the pile, potential energy is transferred into dynamic energy. Want to receive the digital edition of Pile Buck magazine for free? The Hiley formula can be used to determine the failure load, Qu, and then the peak driving resistance, Pd is given by: Janbu suggests that the driving energy (WH)c, needed to avoid damage is limited by: Various Other article related to piled foundation posted in bestengineeringprojects.com, you may like. & 1I`w@h>Ql3*ca:z+^K_eoL*[6[k`Rf~)T_D->2[LhsW{=n8h# ~/-sI+&N_{5[yM2ev$lkQdg;Eh17|5NzuxM;vO9:d,Fxt7L%o]wXwoe{}c~n'{bvJ='bQj'x0. Further advantages of the ABI Mobilram include optimal stability with high working loads, self-propelled carrier with high engine power, low manpower requirements, and a variety of attachments. If you are not able to do an internal inspection you will need to evaluate the problem using dynamic measurements. These early steam hammers relied solely on the drop of the ram for the energy used to drive the pile. As a result, intense strains near the piles often occur. Inspect the inside of the pile for damage to the pile toe. endstream endobj 68 0 obj <>stream If there is no indication of a weathered profile above the bedrock, the pile toe is probably damaged. h\k - hdif&aYL\LG83,a8Isc?t0,T0bx+K}xayVhZF= r Outer diameter of impact block: 1189 mm (4 ft) Preparation and contingency planning are the key to keeping a pile driving project on track and on budget. Width: 590 mm 23 in A hydraulic hammer incorporates the use of an external energy source to lift the hammer to the top of its stroke. Stroke with MRZV 30VV attachment: 69 ft. Energy at fuel setting 3 280275 ft-lbs . 0000002455 00000 n For the single acting hydraulic hammer, the free-falling piston develops the actual energy induced into the pile, much the same power stroke as a drop hammer or a single acting air/steam hammer. Eccentric Moment: 50.2 kgm 4357 in.lbs Pile Clamp Force: 200 tons Click Here to join Eng-Tips and talk with other members! For example, pile penetration =24.9m, final 10 blow set reading = 38mm, design ultimate capacity 120Kn,factor of safety 2.0,hammer efficiency 0.8,weight of hammer 5 tonne, weight of pile 3.54 tonne( dia 300mm spun pile),coefficient of restitution 0.55,assume compression 0.016m and drop of hammer 0.55m. The diesel hammers are the only constituent of this class, although other types of fuel are being used. Keep in mind that driving the piles alters how the soil around it will behave. High Strain Dynamic Load Tests, also called PDA tests, assess the capacity of several piles in a single day. (1930) Pile-driving calculations with notes on driving forces, and ground resistance. You have almost the same situation that I have. A) The hammer energy is converted as = 40 12 = 480 kip-in. Upon impact, the ram pushes the impact block, hammer cushion, helmet, and pile head rapidly downward, allowing the cylinder to fall under gravity. The self-regulating characteristics of a diesel hammer are remarkable. When using a wave analysis software program to predict pile behavior, you may run into data issues. Sounds like we all pretty much agree. Join your peers on the Internet's largest technical engineering professional community.It's easy to join and it's free. We doesn't provide crosshole pile testing system products or service, please contact them directly and verify their companies info carefully. Carrier: Sennebogen SR 35 series F ADOT must implement pile driving soft-starts whereby hammer energy is gradually ramped-up ADOT must employ at least three PSOs to monitor the harassment zones; ADOT must submit a draft report detailing all monitoring within ninety calendar days of the completion of marine mammal monitoring or sixty days prior to the issuance of any subsequent . Max: 935.9 kNm/ 688,145 ft lbs If there is no indication of soft layers, the pile may be damaged below the grade. Many of todays pile driving hammers are powered by diesel or hydraulic systems. Dividing the pile into a series of springs and masses; Integrating the model using a first order finite difference technique; Modeling the hammer and pile cushions using a static hysteresis technique; Modeling the soil as a combination of velocity-dependent dampers and displacement-dependent dampers; and. Calculates soil resistance, dynamic pile stresses, and estimated capacities based on field observed blow count, for a given hammer and pile system. While pile-driving may seem like a simple process driving a pile into the ground using force successful pile-driving actually requires knowledge of multiple types of engineering. Advantages of Double, Differential and Compound Acting Air/Steam Hammers, Disadvantages Double, Differential and Compound Acting Air/Steam Hammers. 0000009574 00000 n The projects risk mitigation plan can consider likely issues to be encountered. If previously installed piles move laterally when new piles are driven, soil displacement is the likely culprit. Reduced fuel should only limit how "hard" the hammer hits at practical refusal. In the Roman world, driven piles were commonly used to provide a stable foundation in the various soils around the Mediterranean Sea. Diesel hammers were first introduced in the United States after the Second World War. Note that cracks discovered early may be repaired with epoxy. Increasing strokes in hard driving provide increasing energies. First, it used steel coils springs to provide dampening for the crane boom and hook; modern machines typically use rubber springs. The helmet is the heavy and rigid steel block between hammer and pile. Amplitude: 1 in (25.4 mm) The dynamic formula was the first attempt to create an equation that would model the dynamics of pile driving and make it useful for contractors. It transfers a large portion of the kinetic energy of the ram into the pile. This is a com-mon practice allowed by OSHA. : 14,065 lbs Why don't you do a quick manual check calculaton using the Gates Formula? Maximum energy: 9,000 ft. lb. Excavations are often not a viable solution where the obstructions are located beyond three feet or below the water table. Unanticipated movement of piles is another indication of a problem that needs to be resolved before work continues. Stroke dependent on hammer-pile-soil system. Concrete fill pipes were used in other applications, and were driven with mandrels. ): 1409 kN 159 tons 0000005436 00000 n Title 24 Calcs is a service provider of the California Title 24 energy compliance, we provide Title 24 compliance services for residential and commercial buildings-Submit your Project 657-234-0134 projects@title24calcs.com Where the blow count is much lower than anticipated, review the soil borings. An optional sheet pile adapter makes the 36-3000 an effective way to drive sheet piles in soil conditions where a vibratory hammer cannot achieve the required depth. 867 49 High eccentric moment and vibration amplitude. For pressing, the . (216) 831-6131 0000011637 00000 n Sometimes the pile driving hammer is the cause of problems. 0000010501 00000 n Amplitude: 24 mm 0.9 in They are categorized by how they attach to the pile driver hanging, fixed, or swinging. Many attempts have been made in the past to determine the relationship between the dynamic resistance of a pile during driving and static load carrying capacity of the pile. The cylinder is open at its upper end, thus allowing the ram to partially emerge from the cylinder. 0000003604 00000 n The ram is raised then released and allowed to free-fall. It will keep going until it runs out of fuel or is manually stopped. 0000105795 00000 n GRLWEAP14 is the pile driving simulation software of choice worldwide for pile driving professionals: Have a technical question? Deep foundation: decide between driven piles and a deep foundation system. Hammer Length: 8832 mm (29 ft) As a result, fewer piles and smaller footings could be used for the same load when using concrete piles (as compared to timber piles). PILE BUCKS TOP RECOMMENDED IMPACT HAMMERS AND VIBRATORY DRIVERS. In the 1960s, the WEAP program added another element: the combustion complexities of diesel hammers. The vertical advance of a pile under a given hammer blow is used as a measure of the piles bearing capacity. Later, the stress wave theory was used to compare the pile force and velocity at a given time. A. PPENDIX . Unlike structural design, the design of pile foundation is not neat and precise. The ultimate capacity of the piles are suppose to be 225kips. It is based on the soil and the driving system. High quality German materials and workmanship ensures near indestructible reliability. Thanks for your reply, Riggly. Blow counts are calculated in advance. Check for toe damage. endstream endobj startxref Overall length: 4300 mm 0000000016 00000 n 0000001276 00000 n St. Louis, MO 63042, Web Design by Captiva Marketing | Privacy Policy | Site Map, Cookies are used to enhance your viewing experience. Instead of attempting to broadly characterize pile behavior, it makes more sense to work to understand the factors that influence the successful design of pile foundations. Our range of vibrodriver H/HD with standard frequency and fixed eccentric moment. The first machines are in the 30 to 40 Hz range that are designed primarily to minimize vibration of neighboring structures. 0000124205 00000 n Promoting, selling, recruiting, coursework and thesis posting is forbidden. Most impact hammers have some type of cushion under the end of the ram to protect the hammers striking parts from damage. Hammer Length w/starter guides: 9449 mm (31 ft) Pile driving is a critical part of the construction process. (Something that should be done before the work is started.) The comparison of these two results demonstrated that impact-vibration driving is substantially more efficient in terms of maximum driving depth and pile installation speed. Agree? Min. Max Width: 0.910 m Thank you for helping keep Eng-Tips Forums free from inappropriate posts.The Eng-Tips staff will check this out and take appropriate action. The timer allows for flexible control of the output energy. In addition to bi-monthly magazine subscription, get weekly emails with our latest articles. 616%*\Hp9TKEy{, H= qvU o\nkLdRJ%Un{)\+sVzO?DeeW#D^q{UFR. Concrete piles are subject to various kinds of cracking. Tripping device approx. If the specific hammer you are using is not listed when you are entering wave analysis data, use a hammer of the same type. Others use a purely hydraulic system to control the valve and thus the cycling of the ram. <<2ED5FEA555CE804986B1E7470E81176F>]>> E -2 . Diesel hammer has a more exact shape compared to other hammers. Pile Driving Equipment Selection and Penetration Limitations, Types of Drilling Systems, Tools, and Mounts. There are several problems that can arise in the field. Total Weight W/O Clamp: 6150 kg 13559 lbs This condition meets the workload that more. A hydraulic hammer incorporates the use of an external energy source to lift the hammer to the top of its stroke. GRLWEAP14 simulates motions and forces in a foundation pile when driven by either an impact or a vibratory hammer. Our DE-30 did not have an adjustable fuel supply. Send us your drawings, using our e-mail: energy@title24ez.com. When Wave Equation Analysis is used instead of Dynamic Formulae, several codes and standards of practice allow a leaner foundation design translating to lower factor of safety or higher resistance factor. It is necessary to have driving accessories of various types and sizes inserted between the bottom of the hammer and the pile to both mate the two geometrically and transmit the impact hammer force to the pile. This type of hammer involves a vibratory pile driver that imparts both vibrations and impacts while driving the pile. The need to use pile penetration rate as the means to end driving. Cleveland, OH 44139 USA This includes an understanding of how the pile will interact with the soils (geotechnical engineering), the dynamics of moving bodies (engineer mechanics) and the stresses during driving and after installation (structural engineering). The ram of rod-type diesel hammers runs on columns that are similar to those in air/steam hammers. If the observed blow count is less than calculated, soil resistance is likely lower than originally estimated. M. ANUAL . The impact-vibration hammers used on this project were able to outperform conventional vibratory, air/steam and diesel hammers. This includes interaction between engineers during the design state, consulting with experts, and talking directly to drill crews and laboratory personnel. In the twentieth century, greater driving force was achieved by using air- or steam-powered machines to accelerate the rams downward action. = 3.0) simple and relatively reliable s Qu EWRh 25 Develop and execute subsurface exploration program: make decisions about what information must be obtained at the site. 0000005665 00000 n endstream endobj 65 0 obj <> endobj 66 0 obj <> endobj 67 0 obj <>stream The energy moves the ram upward, and in some hammers, downward as well. Sign up here. startxref There were two types of these kinds of hammers. Energy output is very sensitive to proper valve timing, and to pressure and volume of the motive fluid. Each blow is more difficult to inspect and verify. I'm just perplexed that anyone would call for a driving criteria of 10 blows per foot and that the project engineer would agree. Originally BSP designed and developed the DX hydraulic hammer range to meet the technical and equipment requirements of contractors engaged in installing equipment and maintaining the UKs rail network. They drive piles faster and their operation is (comparatively) quieter. For the single acting hydraulic hammer, the free-falling piston develops the actual energy induced into the pilemuch the same power stroke as a drop hammer or a single acting air/steam hammer. Since 1980,HPSI has been designing and manufacturing the highest quality, most dependable, and longest-lasting vibratory hammers and hydraulic systems on the market. To successfully translate the pile design into construction, the engineers must rate the requirements of the static analysis methods, the dynamic methods of field installation and construction control. Please let us know here why this post is inappropriate. Height w/o Clamp: 81 (207 cm) Be aware of reductions in actual hammer energy. As per the Engineering News formula the allowable load of driven pile is given by: Where, Q a = Allowable load in kg W = Weight of hammer h = Height of fall in cms s = Final settlement per blow known as set c = Empirical constant (c = 2.5 cm for drop hammer and 0.25 cm for single acting and double acting hammer) 0000007185 00000 n Another possible cause is a combined tension and bending that is too high. Find out which version of GRLWEAP is right for you. The resulting formula could then be applied to the work at hand. Relatively heavy hammer that requires higher crane and handling equipment capacities. : 113,538 lbs However, you may need to choose a different hammer even a different pile type. The cylinder is closed at its upper end, thus causing the ram to compress the air trapped between ram and cylinder top. It may be that the calculated stresses and blow counts are too high. Traditional pile driving machines work by using a weight placed above a pile that releases, slides down vertically and hits the pile, hammering it into the ground. Learning about the history and future of driven pile construction can help to inform your choices as you undertake a construction project. Driving Force: 53 tons (472kN) Max Line Pull: 133 tons (1,183 kN) Two types of steel piles were used at this time: H-piles and pipe. Vertical columns made of various materials (wood, concrete, steel, or a combination) are driven into un-excavated soil. In the twentieth century, engineers in the former Soviet Union developed the first vibratory pile driver. A follower is a steel member placed between the pile hammer and pile that allows the pile to be driven below the reach of the leads. endstream endobj startxref Damage to the pile due to overdriving must be avoided, both when penetrating an overlying hard layer and when driving into the bearing stratum to develop the full healing capacity. In soft driving conditions the fuel would ignite before being reaching optimum compression. From the dawn of human history, driven piles were used to raise a shelter above the water or land. Throughout construction, knowledgable engineers should supervise and inspect the installation of the piles. Hydraulic impact hammers can be single acting, double acting, differential acting, or other variations. Care should be taken to avoid excessive driving, which can lead to pile damage and/or foundation cost overruns. New constructions, Additions, Alterations, Secondary units: ADU, ADQ, in-law unit, granny flat, studio, etc. 1o 6,9X7hMgDpND^qo3:lC_Qt %{#H,HjclL{e+u1CE2^yVlUmB W)7?q2.Z,1]y>v%=Dv]27S|Iu`n YDk8{7SzMd@&b'9x4FHgPzj}j3p>Q x}xw);{Y|n9i[\o3eU'!QvyOmD3=@K>5=.Tx ~/`ytikh,;} [ The majority of diesel hammers manufactured today are the tubular, air-cooled type. This engineer can assist in selecting the pile type, estimating pile length, and choosing the best method to determine pile capacity. Amplitude: 1.12 in The lead, also called the set of leads, sometimes including a brace that allows for the adjustment of the lead angle. hbbd```b``"/H q1dqN`5`6XL_`,`v5T\`[X@$CdI@=J&FN!zF~N|` b{ The dynamic formula used Newtonian impact mechanics as a way of modeling the motion of the pile. *Bearing capacity based on the basic Engineering News formula: Bearing capactiy (tons) = [2e/ (s+0.1)]/2000 where e = Hammer energy (ft lbs), s = Pile set (inches per blow). In 1969, the Americans introduced their first hydraulic vibratory hammer, the MKT V-10. Buildings close to the ground treated by the resonance- free vibratory hammer method are often vulnerable to excessive vibrations. 0000002646 00000 n First, 10 to 12 blows per inch is really outlandish even though the criteria has been around quite some time. The relation suggested by Janbu for ultimate capacity of the pile is: E = Modulus of elasticity of pile material. Concrete-filled steel pipes may include caissons, bulb piles, Monotube piles and shell piles. trailer Thanks for responding. Using fiber optic sensors for pile monitoring allow you to measure stresses along the entire length of the pile during driving. During the Roman era, piles were made of wood. crosshole pile testing system. 2435 0 obj <> endobj Identify the broadest possible selection of hammers for the job. The results of influence of installation methods, show load-carrying capacity increments of 10% in bored piles, 20-22% in hammered driven piles, and 20-30% in vibrated driven piles [14]. hXmo(+| "[n]OMcGW6J'f`f`P"cb(I C!I$Q3(ar@&UDT"cU)I a11c`TUJ`c{Ya`VqV-M& seCh0 u]SN`p8 qn}&? \G]5$3i7!C=jl!VZ\Hh!!7<>N0K3;y}(+tUDcUo__FnUU/4"mfE>? Most of the load capacity is generated from skin friction. The helmet, which aligns the pile head and hammer. But it is a complex process that requires extensive testing and accurate calculation. 0 This Soviet technology was licensed to the Japanese, who then developed their own vibratory hammers. This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. If they are matched, make sure the driving system operation conforms to the equipment manufacturers guidelines. 0000008418 00000 n The challenging aspect of dealing with soil presents a variety of problems that can be anticipated. Smiths technique consisted of five primary elements: The soil model that Smith proposed is still standard in many wave equations in use today, including the Texas Transportation Institute program, which was developed using Smiths model. hb```nng^e`0p,`d`x2CS{&b4qCtuj \6@1 I74Ebx^>Z!pCbc5=*d$ iF@ZCf G While timber piles were typically driven to less than 50 kips allowable capacity, concrete piles could be driven to 60 kips or greater. 100 0 obj <>stream One option is to increase material strength or make design changes. Each rotating eccentric produces forces acting in a single plane and directed toward the centerline of the shaft. The helmet weight (more properly mass) must be known to evaluate the drivability of a pile using the wave equation. 0000003471 00000 n It is guided by columns or inside guiding enclosure. 2. OMS vibro hammer is a world brand in the production of vibratory pile driving equipment, with its products performing in all conditions around the globe. Over time, Americans have developed a unique type of vibratory hammer with slim throat hammers for sheet pile driving, hydraulic drive, and high power engines, pumps and motors. Impact Block approx. Drop hammers are typically used on very small projects and for small piling. You should also evaluate tensile stresses along the pile and compressive stresses at the toe. First, they could operate without an external power source. The hammer is connected to a cable that is attached to a winch on the crane. For a given hammer, varying the drop height can vary the energy per blow. The direction, location, and severity of the cracks provide clues to the cause. *Eng-Tips's functionality depends on members receiving e-mail. 0000008195 00000 n Otherwise, they may end up in the pile heap. One cause for damage near the head of a concrete pile is insufficient pile cushioning. (I know that some agencies require all piles to be driven to refusal at 20 blows per inch). It should not allow more than approximately 2 inches (50 mm) of lateral movement. In 1887, Vulcan Iron Works developed the first #1 hammer. Pile Type Hammer Energy Rating (ft-lbs) Number of Piles Strikes per Pile. Construction control: supervise and review pile driving as it occurs. 0000011503 00000 n A stone block would be lifted by ropes, which were stretched taught by humans and arranged in a star pattern around the pile head. In addition, pile drivability should be considered during design, as large costs may be generated if the piles that have been selected and planned for cannot be driven. Hn6s)zn ]^t]Y2(EAYE.|w?. Developed for deep underwater pile driving up to a depth of 2000m, they can be used for all offshore piling jobs, including driving pipeline initiation pile, piles for jackets, conductors and mooring systems. Low strokes in easy driving protect concrete piles. Uncertain energy when combustion prevents ram-anvil impact. When the weight reaches its highest point, it is released. I'm not saying you are wrong, just that you are in the minority so far. Pile driving is the process of installing a pile a braced, structural column into the ground without first excavating the area. A crane hoists the weight, which acts as a large piston. %%EOF Sonic or Resonant Hammers. In a class by itself is the resonant pile driver, first introduced in the early 1960's. The central principle of the resonant driver is to induce resonant response in the pile. Raymond founded the Raymond Concrete Pile Company, which became one of the largest and most successful pile driving business in the world. The recommendation was drive to 25bpf, which was within the range of the WEAP analysis. Fast delivery and professional after sales team. The operating rate of single acting air/steam hammers range between 35 and 60 blows per minute. The development of the steam hammer, use of concrete piles, and the creation of the first dynamic pile driving formula permitted even more efficient installation of piles. CAT C18 tier 4F diesel engine Through the utilization of diesel fuel, the hammer acts like a very large engine. C. ALTRANS F. OUNDATION . 2.1 Hammer energy The minimum pile wall thickness recommended by the American Petroleum Institute (API, 2007) for offshore piles subjected to hard driving (250 blows/300 mm) is given as: t = 6.35 + d/100 (1) 0 Rifle-bored top plate delivers oil to motors without using hoses, Patented one piece helical gear/eccentric eliminates gearbox failures caused by broken pins, keys, bolts or splines found in all other vibro gearboxes, Giant double roller spherical bearings for super long life, Center safety pin shows the line load on pile and cranes. It should have a similar energy rating and ram weight. Advantages of Single Acting Air/Steam Hammers, Disadvantages of Single Acting Air/Steam Hammers. Geotechnical engineering principles that account for the uncertainty created by the use of soil and rock advanced the formulas used for pile-driving. Trip assembly includes safety mechanism to prevent unintended engagement during operation. When I-piles were driven in compact sand and gravel for bridge piers and abutments, scour undermining often occurred. This is best demonstrated through an examination of pile dynamics. We have received your request and will respond promptly. Among these the Hiley Formula and Janbu Formula are convenient to use and give reasonable predictions of ultimate bearing capacity of driven piles in granular soils. The process of designing and constructing a pile-driven foundation is unique to other types of structural design and construction. Shipping Weight w/ 200 Bundle: 23,700 lbs (10,751 kg) If the hammer is not aligned properly with the pile head, eccentric loading can cause excessive stresses that result in structural damage of the pile. Perform restrike or static load testing to confirm capacity. Login. These include hammer performance and alignment issues, as well as poor pile quality. Since the ram falls only under gravity, the OED is also called single acting. The Pile Driving Analyzer (PDA) system is the most widely employed system for Dynamic Load Testing and Pile Driving Monitoring in the world. These relationships are called pile driving formula and have been established theoretically and empirically. Appealing to the ENR formula, we have Applying the factor of safety gives B) The weight of the pile + cap ensemble is = 9 + 2.4 = 11.4 kip. Learn More, - Learn about career opportunities at Hammer & Steel, Operating Weights - Hammer w/ drive cap (lbs). The analysis of battered (driven at an angle) piles has been enhanced in GRLWEAP14. Driving system problems can be related to low hammer efficiency or cushion that is too soft. In this situation, pre-drilling of pile locations can be employed. Pile Driving Acceptance Criteria, or 2006 SS, Section 49-1.08, Pile Driving Acceptance Criteria. A restrike test is needed to determine changes in the soil strength.