Geotechnical monitoring during complex reconstruction on weak soils

Abstract

General recommendations are presented for geotechnicai monitoring, and an example of monitoring during construction of a transportation-commercial complex in the center of Saint Petersburg is given.Geotechnical monitoring is one of the most important components of the geotechnical accompaniment of urban reconstruction [1]. Monitoring attaches special urgency under conditions where weak clayey soils prevail, and is conducted to ensure the reliability of structures being raised, and preservation of the surrounding setting and utilities. It is a tool for the on-going correction of work production during site development and substructure installation.The existence of a well-founded structural solution and a flexible procedure for performing work is a necessary, but insufficient condition for successful construction. A multitude of additional factors affect the production process: the qualification of personnel, the condition of the equipment, observance of rules, etc., as well as noncorrespondence between the computational schemes employed for geotechnical substantiation of the contractor design and plan for work production, and the actual geotechnical situation.The geological and hydrogeological media, capital development, and critical utilities located in the zone of risk associated with the construction or reconstruction of an entity should fall within the sphere of monitoring, in addition to the construction site.Monitoring consists of two stages -preparatory and operating. The following work is performed during the preparatory stage: 9 analysis of initial information on results of inspection of the surrounding setting; 9 examination of the technical status of the surrounding setting in the zone where monitoring is being conducted, and recording of defects. 9 determination of background parameters of the oscillation of building structures due to on-going influences (transport, work in progress nearby, etc.); 9 the installation of crack-opening beacons and sensors; 9 determination of the tilt of building walls, and the nonuniformity of settlements; 9 the installation of inspection wells for monitoring the ground-water table, and the installation of geodesic marks; and, 9 more precise definition of design criteria with respect to permissible effects.