Analysis of deep excavation project design and construction coordination and management

[Abstract] how to do a good job in construction management of deep excavation for the structure of the main construction can be smooth, high quality, which in the current urgent need to resolve an issue.

[Keywords] construction, deep excavation, design and construction; Management

The current construction of deep foundation pit design and construction, there are still many places is not perfect, is for the construction of deep foundation pit design and construction of the status quo, then presents a deep excavation works, many problems exist, in the design of the foundation pit design, design plan submission, the slope term preloading, construction of temporary structures such as building layout requirements for a clear description of the construction works on the programming and issued, the construction process control, groundwater control, etc. described in detail.

A deep excavation design and construction status
The current construction, which because of its deep excavation highly specialized, are generally subcontracted to specialized geotechnical construction company, large companies generally design and construction unit of the local survey, in addition, there are some scale and stronger professional company, the current market, there are some individuals geotechnical company from design and construction quality point of view: large geotechnical construction quality professional construction company have both design qualification, and some small rock construction quality professional construction company only, and no design qualification, in the current situation in the relatively large number geotechnical engineering.

The last two years, some owners start to advance a variety of factors, routine changes in the tender, the underground structure of the main geotechnical engineering part of the tender before the tender, followed by the emergence of some new phenomenon: the total number of large construction contractors in order to seize the market, have participated in the bidding, some large construction general contractors into geotechnical engineering, however, whether the owners or supervision units, they are ignoring the construction general contractors are generally not qualified geotechnical design problem, which gives a lot of future risks caused by the construction from the contract model to see: foundation pit construction subcontracting generally, some owners directly subcontracted to a professional excavation company, and then into the general contracting unit of management , while the other model is that the owners will be assigned the task of excavation general contractors, and sub-units by the general contractor, former owners of a model for direct sub-tasks, so the total package in the management of easy to occur when management difficult problem, and then a model prone to quality problems.

Features from the deep excavation to see: deep excavation depth, a lot of deep excavation adjacent to other buildings (or structures, construction difficult, in addition to rational design, construction management must be strengthened to ensure strict accordance with design specifications and related construction, the need for pit slope and surrounding buildings (or structures to strengthen the monitoring and implementation of information technology construction.

2 problems encountered in the construction
2.1 Pit Slope collapse.

This situation generally occurs in the pit and excavation construction phase just shortly after the end of construction in Beijing's Chaoyang District, Wali of a site, excavation has just completed less than two days, the overall collapse of the slope from top to bottom, length of up to 50 meters. The reason for supporting the construction unit without a reasonable design, there is no strict accordance with the design and construction, from the collapse of the slope, despite the soil nailing, but not by soil nailing specification the Most grouting of soil nails is not just to play some holes to insert steel, although some note the slurry of soil nails, but the hole is not filled with slurry, and some did not soil nail hole punch, but the soil hit the nail directly buried rod body.

2.2 slope greater horizontal displacement.

Horizontal displacement of a large number of pit slope, reaching more than 4cm, and by monitoring the level of displacement continues to increase. Faced with this situation, the structure of the main body construction units to stop the underground construction, the owners had immediately called excavation protection design, construction units and experts on the stability of re-excavation analysis, and to propose measures to deal with problems.

2.3 near the building deformation.

In urban construction, many pit adjacent to the building, slightly improper handling, nearby buildings on the easily deformed. In general, buildings are the deformation caused by foundation settlement. Building a larger deformation, not only endanger the upstairs residents or staff safety, but also a threat in the facilities of the project, the project was difficult to continue.

3 deep excavation design and construction Suggestions
For the construction of deep foundation pit of the situation in order to follow the structure of the main construction of a smooth, safe and orderly manner, especially for deep excavation design and construction make the following recommendations.

3.1 clear foundation pit design unit.

More and more deep excavation, and deep pit collapse incidents also occurred frequently, preventing deep excavation for the accident, local authorities introduced a number of mandatory documents of the deep pit, all of which illustrate the deep base pit construction accident severity and the importance of good deep excavation in the deep excavation, including geotechnical engineering, including construction units, design units are generally the same time. Only a clear design of deep excavation units, submitted a design of deep excavation unit of qualification, which in the future when problems arise, such as the construction can easily find the responsible units and persons responsible, traceability strong. Links to free download http://www.hi138.com
3.2 submit bids and construction of foundation pit design.

Deep foundation pit construction is based on the design of deep excavation, so strengthening the deep excavation design review and supervision is necessary. Both in the foundation pit tender or excavation prior to construction, excavation should be submitted separately design, design, and design on the cover should have a designer, review and approval signature so that the base supporting the construction of pit problems such as design changes to be done before we can quickly find the designer, but also easy to quickly solve the problem, but also to facilitate accountability.

4.3 special construction plan preparation and issued.

In the foundation pit construction, special construction plan should be prepared. Taking into account the reporting, review and return period, special construction plan should be prepared in a few days before construction, supervision and timely reporting. Supervision should seize the approval, to return promptly after the approval of construction flat for onward transport of the construction units to timely and accurate relevant departments and personnel. the construction units in the program received formal approval before the construction works may not be in the current foundation pit construction, construction program is not approved before the start of construction situations have occurred, which, as the standardization of construction of deep foundation pit should be avoided.

4.4 Construction process control.

Deep foundation pit construction, process control should be strengthened. The construction must be designed in strict accordance with excavation, foundation pit construction design, technical tests, and related norms for construction. Construction, such as unusual circumstances, should be on-site technical person in charge according to the nature and size of the excavation report designer, the designer should be promptly carried out according to the situation on the design changes, the problem is nipped in the bud.

4 Conclusion
For deep excavation design and construction to strengthen the management, to do deep excavation design and construction, the need to address the following aspects.

4.1 Design should take into account the design of deep excavation basis and conditions, it's a good deep excavation project prerequisite.

4.2 deep excavation should pay attention to design, enhance the overall management of the design, bidding should be individually designed to provide foundation pit.

4.3 is the foundation pit construction projects to ensure the safe, ensure the smooth conduct, should strengthen the construction process control.

4.4 "4" Water is the enemy of deep excavation, should pay attention to the control of groundwater while groundwater as a valuable resource, should be limited to the blind, over-pumping down.

4.5 deep excavation design and construction management has not been the people's full attention and do deep excavation design and construction management for small excavation projects to reduce or even eliminate accidents, construction norms will play a positive role. Links to free download http://www.hi138.com