A Construction Method for Reinforced Bridgehead Subgrade of Expressway in Collapsible Loess Area

Abstract

The invention discloses a reinforced bridge head subgrade of highways in collapsible loess areas and a construction method thereof. The subgrade sequentially comprises a sand-mixed lime soil pile composite foundation, a reinforced sand-mixed lime soil cushion, and a reinforced sand-mixed lime soil modified loess from bottom to top. Backfill, composite geomembrane, graded crushed stone bedding and bridgehead strapping. Sand-mixed lime-soil pile composite foundation uses sand-mixed lime-soil as the pile body material to be filled in layers into the pile holes. The reinforced sand-mixed-lime-soil cushion layer is composed of river sand, lime and loess in proportion. Two-way geogrids are evenly laid at a distance of 0.2m for reinforcement, and the reinforced loess backfill layer mixed with sand and lime is composed of river sand, lime and loess mixed in proportion to fill, and two-way geogrids are evenly laid at a vertical distance of 0.6m during filling. grid. The compressive, tensile, shear strength and stability of the subgrade at the bridge head are good, which can eliminate the problem of "jumping at the bridge head" caused by the uneven settlement and deformation of the subgrade at the bridge head, and at the same time enhance the water stability and frost resistance of the subgrade at the bridge head performance.

Description

technical field [0001] The invention relates to the technical field of special expressway subgrades, in particular to a construction method for reinforced bridgehead subgrades of expressways in collapsible loess areas. Background technique [0002] With the rapid economic development and increasing traffic volume in western my country, the scale and quantity of high-grade highways in the collapsible loess areas of Northwest China are increasing day by day. In Northwest China, most of the newly accumulated loess and the Neo-Pleistocene loess and paleosol are collapsible loess. The thickness of collapsible loess in some areas is relatively thick, and the collapsibility grade is severe to very serious. The collapsible loess is a kind of porous Quaternary sediment with columnar joints formed under dry climate conditions, and it will produce large subsidence after soaking in water. At the same time, the bridge abutment of the expressway is generally high, and the backfill soil ...

AI Technical Summary

Problems solved by technology

[0005] The present invention provides a construction method for expressway reinforced bridgehead roadbed in collapsible loess area, which is used to solve the problem of "jumping at the bridgehead" caused by uneven settlement of expressway bridgehead roadbed in collapsible loess area. At the same time, improve the water stability and frost resistance of the subgrade at the bridge head in the collapsible loess area of ​​Northwest China

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