3 Common Problems and Countermeasures in Deep Foundation Support

There are many successful cases of deep foundation support design and construction in geotechnical engineering. However, from the perspective of implementation effect, there are some problems in some foundation support projects that have not met the relevant technical standards and quality requirements. Therefore, it is necessary to analyze the problems and deficiencies exposed in previous projects in order to improve the design and construction level of deep foundation support.


Common Failures of Deep Foundation Support


geological conditions

1. Insufficient surveying and research of the terrain

In order to ensure the stable performance of the support structure, it is necessary to fully understand the engineering geological conditions and hydrogeological conditions of the site, and fully analyze the physical and mechanical properties of the rock and soil mass of the foundation slope.

Hydrogeological conditions are the focus of survey work. Especially in sites with complex topography and geomorphology, not only the rock and soil structure features are more complicated, but also the hydrological conditions change with the seasons resulting in uneven spatial distribution. Special hydrogeological surveys should be carried out to meet engineering needs.


2. The overall function of the support system and the support environment have not been fully analyzed

In the design and construction of deep foundation support, if the conditions of the entire excavation were not considered, it would inevitably have a certain impact on subsequent construction. In the construction process, the deformation of the foundation support structure and the surrounding soil will develop to a certain extent with the passage of time, and it is also closely related to the shape, size, and depth of the excavation of the foundation.

In the design of deep foundation support, if the designer fails to fully consider the ability of the support structure to resist deformation and the influence of the surrounding environment, the support system will not be effectively integrated into the entire engineering environment and cannot fully work.


3. The construction management and quality of foundation support do not meet the requirements

During the foundation excavation and support process, there were problems such as excavation and support not being in accordance with the design conditions, over-excavation, support not in time, and construction operations not being carried out in accordance with the designed construction sequence, which affected the stability and safety of the foundation.


Construction Strategy for Deep Foundation Support

foundation support with self drilling anchor bolt

1.    From Design Aspects

l  Soil Nailing Wall Support

Soil nailing wall support is a relatively traditional construction technology, generally used for foundations below 12m with a simple surrounding environment and low deformation requirements. As a temporary support method, the service period of the soil nailing wall shall not exceed 1 year.


l  Anchor-Pile Support

Anchor-pile support can effectively strengthen the rock mass, control the deformation of the foundation, and reduce the probability of foundation collapse. The anchor rod can effectively control the deformation by applying the prestress. Through grouting, the cement slurry penetrates into the soil around the anchorage section to improve the shear strength and friction of the soil. The self-drilling anchor bolt integrates drilling, grouting, and anchoring to improve drilling efficiency and anchoring effect. It has been widely used in foundation support projects.

After drilling the anchor rod, the tension test and the creep test in soft soil should be carried out in time, and adjust the parameters accordingly.


2.    From Construction Aspects

Pay attention to the detection of foundation deformation to avoid the impact of excessive deformation on subsequent construction. The construction shall be carried out in accordance with the design regulations, and the exposure time of the slope after the excavation of the foundation shall be shortened as much as possible. During the construction process, a corresponding drainage system should be set up to prevent domestic water and rainwater from eroding the slope, and antifreeze measures should be taken in winter.


When carrying out the design and construction of deep foundation support, it is necessary to fully understand the engineering geological conditions, hydrogeological conditions, and surrounding environmental factors of the site, and combine engineering experience to choose an economical and reasonable deep foundation support form and construction plan. If you have any questions about self-drilling anchor bolts or foundation slope support, please contact sinorock@sinorockco.com.





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