With the development of economy and society, urban building land tends to be tight, especially for the first and second tier cities, urban building land presents a high plot ratio, complex building surrounding conditions, narrow plots, etc.
Therefore, many development projects need to build multi-storey basements, in order to ensure the safety of the underground structure construction and the surrounding environment of the foundation pit, it is necessary to use the support, reinforcement and protection of the side wall of the deep foundation pit and the surrounding environment, which is the deep foundation pit support.
There are many ways to support deep foundation pits, which need to be selected according to the actual situation of the site and the comprehensive comparison of economy.
01 Commonly used foundation pit support form
02 Focus on foundation pit support
03 Selection of foundation pit support form
04 Economic analysis of foundation pit support
Commonly used foundation pit support form
There are many ways to support deep foundation pits, and the common forms are as follows.
Focus on foundation pit support
1.Basic information is important
The following information is required for the support design.
In particular, the following information needs to be paid attention to, which is very important for the safety and economy of deep foundation pit support.
1.1 Geological data
Preliminary survey, detailed survey or special survey of foundation pit.
1.2 Information on the surrounding environment
Topographic map: 1:500, 3 times the depth of the foundation pit beyond the red line;
Underground pipelines: 20-30m beyond the red line
Surrounding buildings: basement, structural form, basic information.
Subway (if any): general plan, cross-section.
1.3. Main design data
General plan: coordinates, main layout, basement extent, outdoor elevation.
Basement drawings: basement dimensions, sections, bottom plate thickness, core tube.
Foundation: Foundation form, depth, layout.
2.Focus on what's important
2.1. Foundation pit safety - design and construction quality.
It is necessary to repeatedly demonstrate the enclosure structure, the anchor structure and the waterproof curtain.
2.2. Surrounding environment safety - design, information construction, monitoring.
Underground pipelines: pressure pipes, high-voltage electricity, military optical cables, communications.
Surrounding buildings: overall settlement, uneven settlement, inclination, cracks.
Metro (if any): automatic monitoring, settlement monitoring of municipal roads.
2.3. Project schedule - design, process arrangement and construction organizationPoke me, the progress can be known and controlled, and the delay in delivery will be eliminatedFoundation pit support and earthwork: convenient for the support form of earthwork and unearthed lane.
Foundation pit support and pile foundation: construction sequence, pile foundation construction elevation, pile foundation detection.
2.4 Engineering economy - the key is the scheme.
Heavy plan: consider whether the plan is safe from the whole, which is conducive to unearthing, the main body rushing the construction period, and conducive to approval.
Geotechnical integration: survey, design, construction.
Selection of foundation pit support form
The selection of the form of deep foundation pit support is greatly affected by geological conditions, so it needs to be judged according to the actual situation of the project location.
1.The main forms of support that can be selected by various geologies
According to the geological characteristics of the area where the project is located, it is classified according to the influence of the stratum on the foundation pit support, and the support mode is selected, such as the Shenzhen area is divided into coastal soft soil area, alluvial plain valley area, and hilly weathered stratum area.
Statistics on the characteristics and support forms of different regions:
2.The influence of rock and soil mass on foundation pit support
3.Selection of support forms with different depths and geological conditions
Economic analysis of foundation pit support
1.Special attention is paid to the cost of different support shapes
2.Comparison of the cost of each support formPoke here, so that the cost is accurate, fully managed, and controllable.
*:China Southwest Construction Survey and Design Research Institute***
Author: Peng Yong
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