AASHTO MSI-88 pdf free download
AASHTO MSI-88 pdf free download.MANUAL ON SUBSUR FACE INVI ESTIGATIONS.
Subsurface explorations for a transportation-related project typically have the objectives of providing: (1) general information on subsurface soil, rock and water conditions on the site or route, and (2) specific information on the subsurface conditions or soil or rock properties that are important to the various stages of project planning. An understanding of basic site geology is necessary throughout the planning process for any project that has major components supported on, or in the earth and underlying rock. In many cases, general geologic information, and in some cases specific information on subsurface conditions in the project area, will be available from technical references and reports, and previous subsurface explorations on and near the site or route.
Whatever the extent of available information on a particular project or site, there may become a need at some stage in the planning process for additional subsurface investigation. This investigation will usually have to be accomplished within budgetary and time constraints that will limit the level of effort that can be applied. It is therefore important that subsurface investigations be carefully planned, and coordinated between those who will obtain and those who will use the information.
The geotechnical data that are necessary for planning a particular type of project will vary from project to project. In the early stages, it may be sufficient to obtain only preliminary geotechnical information for alternative sites or routes to enable planners to evaluate project feasibility and identify major constraints and premium costs. However, these early data must be extensive enough and have sufficient accuracy to be appropriate for these objectives, so that correct planning decisions can be made before intensive design effort is initiated.
In many cases relating to roadways, standard practice for the agency will apply unless unforeseen conditions arise that require special attention. For many states, this means logged borings at 100—175 rn-spacing, with variations providing concentrated data at cut sections, borrow areas, or where geologically-related problems are expected. Structure foundations commonly have individually-planned explorations.
When a project is under construction there is not normally further subsurface investigation, except to resolve questions or problems that have arisen during construction. Design-phase explorations would have provided adequate subsurface information for design and, in most cases, for contractor bidding for construction. However, in some instance there may be a need for limited or local explorations to confirm design evaluations, particularly when there have been design changes subsequent to the main exploration program. There may also be a need for explorations and geotechnical data in connection with construction-phase instrumentation and monitoring.
As previously noted, the geotechnical data that are required for a project can be broadly categorized as general or specific. The first category encompasses identification and delineation of various soil and rock strata and ground water levels. The second category will provide both qualitative and quantitative information on the character and engineering properties of all or part of one or more of the various strata. Data for the first category will normally be derived from one or more of the various methods of subsurface explorations, while data for the second category will quite often require field or laboratory testing.AASHTO MSI-88 pdf download.
