Pile & Foundation Testing
As the UK’s largest and most experienced independent ground engineering contractor, it is important to Van Elle that ‘best practice’ is promoted rather than just typical testing regimes which can often lead to more expense for the client or a less sustainable solution being implemented.
Load testing of piles represents an estimated 5% of the value of the UK piling market and can typically account for up to 10% of the cost of the piling works. Fulfilling its traditional role of design validation and quality control, the testing also provides an opportunity for continuous improvement in foundation design and construction practices, playing an important role in value engineering.
Pile testing can be carried out at various stages of the pile installation dependant upon the agreed design method. Often, the piling can be designed based upon the site investigation data either on a re-measure, or a lump sum basis if the available data is adequate. Sometimes, however, test piles can be installed, tested and the results analysed to ensure that the proposed solution is suitable before continuing with installing the working piles.
The 3 most common pile testing techniques are integrity, dynamic and static load testing, details of which are set out below.
Integrity Testing using sonic pulse echo or transient dynamic response methods is a low cost quality control tool used to detect defects along the pile shaft and, in some cases, give an estimation of the pile length.
Dynamic Load Testing consists of striking the pile with a drop hammer and measuring force and velocity at the pile top. Using stress wave theory the pile top measurements are analyzed to predict the pile bearing capacity. Further computer analysis using the CAPWAP software yields a variety of pile performance data including shaft resistance distribution, toe bearing and static load v deflection data. This test method is an economic alternative or supplement to traditional static load testing and can be applied to all pile types.
Static Load Testing involves the measurement of load and deflection at the pile top. The load is applied by jacking against a reaction provided either by a grillage and kentledge system or a reaction beam restrained by anchorage piles. Pile top measurements from the load cell and deflection gauges are recorded on a data logger from which information on load v deflection and load and deflection v time can be produced.
Other specialist test methods are also available including integrity testing using Sonic Logging, Parallel Seismic testing to determine pile length and Pile Instrumentation to measure various parameters including strain, temperature and inclination.
With the broadest portfolio of products and services in the sector and working for clients, and on projects, of all sizes you can be guaranteed of the quality service, latest innovative equipment, fully trained site teams and professional attitude you would expect from a company of our experience, success and reputation. For more information on our testing or site investigation services, please contact Andy Johnston on 01773 580580 or at andy.johnston@van-elle.co.uk.
