Reinforcement method for transmission tower shallow base foundation under composite soft soil foundation

Abstract

The invention relates to a reinforcement method for a transmission tower shallow base foundation under a composite soft soil foundation. A cement-soil mixing pile composite base is adopted for reinforcement, and the foundation reinforcement method comprises the following steps: (1) pile positions are distributed on the soft soil foundation in the form of square or quincunx distribution mode, and the pile diameter, pile length and pile spacing are determined; (2) pile holes are drilled in the base foundation, cement slurry is injected into the pile holes to form cement piles, and anchor bars are arranged in the cement piles within 2 hours after the cement piles are finished; (3) a mattress cushion layer is paved on the treated foundation, and the anchor bars extend out of the mattress cushion layer; (4) a flexible platy foundation is mounted on the mattress cushion layer, the anchor bars in the cement piles are welded with the main bars of the flexible platy foundation, and the flexible platy foundation is used as a bearing layer. Compared with the flexible platy foundation reinforcement or bored pile reinforcement, the reinforcement method not only can meet the design requirements, extend the application range of shallow foundation, but also can reduce the total cost and have remarkable economic benefits.

Description

technical field [0001] The invention relates to a method for strengthening a soft soil foundation, in particular to a method for strengthening the foundation of a shallow buried foundation of a power transmission tower under a composite soft soil foundation. Background technique [0002] With the rapid development of power grid construction, the basic design of transmission lines is related to the safe operation of the line, and more importantly, the investment and comprehensive benefits of the project. At present, the commonly used foundation types are: ① slab foundation; ② bored pile foundation. Among them, the straight column foundation is generally used in areas with good geological conditions, while the cast-in-situ pile foundation is generally used in unfavorable geological areas such as river ponds and soft soils. [0003] In the area of ​​soft soil foundation, the design of the tower foundation in the soft soil foundation area has its particularity because the desig...

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Problems solved by technology

[0005] (1) The bearing capacity of the foundation of the bearing layer is low, and the shallow covering soil layer is thick, which results in a larger area and deeper foundation burial for the general iron tower shallow foundation (slab foundation) compared with other areas. Deep, the excavation volume of earthwork is large, and the amount of concrete and steel bars is also large

[0006] (2) The width of the slab foundation bottom plate is large, and the foundation is greatly affected by external interference. For example, uneven loading near the tower position or excavation of fish ponds and ditches will cause damage to the stability of the foundation foundation

[0007] (3) For iron towers with a large foundation bearing capacity such as four circuits on the same tower and 500kV lines, if the slab foundation is used, the width of the floor will be very large, and even the slab foundation cannot meet the design requirements, so the entire line must use bored pile foundations

The pile foundation is a deep foundation, and the investment cost is large, and its cost is 2 to 4 times that of the slab foundation, which makes the foundation cost of the entire line very high

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