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When there are the following situations in the design and construction of foundation pit support engineering, appropriate foundation treatment measures should be taken:
The foundation of the foundation pit can not meet the stability requirements of the side wall of the foundation pit;
The expected impact on the surrounding environment exceeds the relevant standards;
The existing foundation conditions can not meet the normal construction requirements such as excavation, grading, floor construction;
The quality problems exposed in the process of foundation pit excavation seriously affect the foundation pit construction and foundation pit safety.
Where there is a risk of pipe surge and soil erosion, reliable and preventive foundation treatment is required in advance. The location and scope of reinforcement should be selected in the geological or environmental conditions that may cause sudden disasters, including but not limited to the following conditions:
Liquid index greater than 10 thixotropic and rheological clay layer, foundation pit excavation is deep, and the soil in front of the wall may undergo excessive plastic failure;
Loose sandy or silty soil layers with abundant groundwater;
There is a large overload in the heavy load area of the equipment at the edge of the pit or outside the pit, or there is a local loose soil or cavity outside the pit;
There are important protection facilities or construction facilities that are sensitive to settlement near the foundation pit:
There is a large slope or a large water level difference around the pit;
Reinforcement of the partially deepened area in the pit.
The influence of foundation pit soil on foundation pit and environment is a comprehensive factor, which is related to the structure type, scale and excavation depth of foundation pit, environmental protection requirements, and construction technology level. Therefore, these factors need to be comprehensively considered when carrying out the foundation pit soil reinforcement design. In addition, the degree of foundation pit deformation and environmental impact is also related to soil properties and environmental conditions. Due to the great changes in the soil conditions and environment of the foundation pit, the surrounding environment of each foundation pit is also very different. Therefore, the soil reinforcement design in the passive area of the pit should be treated differently according to the specific situation, so as to achieve the social effects of reasonable reinforcement design, economic engineering investment and environmental safety.