Preliminary assessment of site investigation contractors with regard to the determination of physical and mechanical properties of soils and rocks

Site investigation (engineering-geological survey) is a very important source of initial data for making design decisions. Based on the investigation data, designers obtain information on the engineering-geological conditions of a construction site, primarily on the structure of its ground base, the properties of the constituent soils and rocks, hazardous engineering-geological processes, as well as other data necessary for making design decisions. As a source of quantitative initial data for geotechnical calculations, field and laboratory testing of soils and rocks should be emphasized within the framework of site investigations. For soil and rock classification and property determination, the "final word" usually belongs to laboratory testing. In modern engineering practice, a common problem is the poor quality of site investigations for construction, resulting in designers receiving insufficient or unreliable initial data. The main reasons for the decline in the investigation quality are cost-cutting, incompetence of contractors, and tight deadlines for site investigations combined with limited instrumentation. To save money and complete investigations on time, questionable labor optimization methods are often used on the basis of fabricated drilling or test results. Poor quality investigations can lead to increased construction costs or decreased stability of buildings and structures caused by the negative impact of the geological environment. Laboratory testing is the primary and most common source of qualitative data on physical and mechanical properties of soils and rocks. So, based on an analysis of regulatory documents and personal experience, the authors have developed an algorithm for a preliminary assessment of the compliance of a potential site investigation contractor with selection criteria regarding laboratory testing of samples. This algorithm is presented in the current article. Some key aspects of the customer-laboratory interaction during the testing are also discussed.