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Is cement soil pile reliable as a foundation pit support method?

Cement soil wall is a non mainstream form of support structure, suitable for narrow soil conditions, and not widely used in practical engineering applications.Cement earth walls are generally used in soft soil foundation pits with small depths.Under these conditions, the anchor rod does not have a suitable anchoring soil layer, which cannot provide sufficient anchoring force, and internal support will increase the difficulty of constructing the main underground structure.At this point, when the comprehensive comparison of economy, construction period, technical feasibility, etc. is relatively optimal, cement soil walls are generally chosen as a support method.Cement soil walls generally use mixing piles, and the wall material is cement soil, which has low tensile and shear strength.When designed with a beam structure, the performance is poor and cannot be compared to concrete materials.Therefore, only when designed according to a gravity based structure can it have certain advantages.

sinovo group

When cement retaining walls are used for silt soil and silt foundation pits, the depth of the pit should not exceed 7m.Due to the gravity based design, a larger wall width is required. When the depth of the foundation pit is greater than 7m, as the depth of the pit increases, the width and depth of the wall become too large, which is not suitable economically, in terms of construction cost and schedule. Insufficient depth of the wall will cause displacement and settlement, while insufficient width will cause cracking or even overturning of the wall. Although cement soil walls with mixing piles can also be used for foundation pits in soil types such as cohesive soil, silt, and sandy soil, it is generally better to choose other forms of support. In special circumstances, cement soil walls with mixing piles can still be used for these soil types.

sinovo

Compared with the retaining structure, there are still some unresolved issues or a lack of mature and unified understanding in the design of soil nail walls. For example, as a structural form, there is no complete practical structural analysis method for soil nail walls, and the problems of soil nail tension and surface layer stress under working conditions have not been solved. The design of the surface layer can only be solved through structural requirements. Relevant regulations stipulate the requirements for surface layer construction, but are limited to foundation pits with non soft soil and no groundwater conditions within a depth of 12m The displacement calculation problem of soil nail walls has not been fundamentally solved. Due to the common practice of soil nail walls in China, which does not apply prestress to the soil nails, the soil nails will only reach their working stress level after a certain deformation of the foundation pit. Therefore, theoretically, the displacement and settlement of soil nail walls are relatively large. When there are buildings or other structures within the deformation affected range around the foundation pit, it is not suitable to use soil nail wall support.

 


Post time: Jan-26-2025