This phase of the survey consists in detailing the survey. The Design Institute arranges 91 boreholes, including 46 technical holes and 45 identification holes, and proposes the following survey contents and requirements:
(1) To identify the type, depth, distribution and engineering properties of rocks and soils in various layers within the scope of engineering, thus to establish their physical and mechanical property design parameters, and analyze and evaluate the stability, uniformity and bearing capacity of the foundation.
(2) To identify the type, factor, distribution range and development tendency of the unfavorable geological effect and the severity of its damage to the foundation in order to propose suggestions for rectification.
(3) To identify the actual soil depth of on-site fills (including the newly-leveled fills), and to analyze the feasibility of filling for the project.
(4) To provide foundation deformation calculation parameters to predict the deformation characteristics of buildings.
(5) To provide the design calculation parameters of the retaining wall.
(6) To identify buried objects which could hinder the project, such as watercourses, channels and ditches, tombs, air-raid shelters and isolated stones.
(7) To identify the occurrence mode of underground water so as to establish the underground water level and its range of change, and to determine the influence of water and soil for pile foundation design & construction as well as the corrosion of construction materials.
(8) On the basis of understanding of local practice, to make suggestions for the foundation type and foundation treatment methods.
(9) To provide pile foundation calculation parameters to evaluate the piling possibility and demonstrate construction conditions of the pile and its impact on the environment.
(10) To present recommendations for foundation pit excavation plans of foundation and underground structures and buildings, and to provide foundation pit supporting design calculation parameters.