Deep foundation pit excavation construction method adopted under pebble bed red sandstone geological condition

Abstract

The invention relates to a deep foundation pit excavation construction method adopted under the pebble bed red sandstone geological condition. The method includes the specific steps that pre-rainfall is performed before foundation pit excavation, after an assigned depth is achieved through pre-rainfall, block separation and grooving excavation are performed till the elevation that the distance from the current position to the bottom of a capping beam is 1m is achieved, and the capping beam is constructed; while the capping beam is maintained, earthwork in a foundation pit is excavated downwards in sequence in a smashing mode from a first concrete circuit purlin bottom to a last concrete circuit purlin, each concrete circuit purlin bottom is supported by a supporting rod piece after being excavated, after the last concrete circuit purlin and the corresponding rod piece are completed, basin type excavation is performed till the foundation base elevation is achieved, and communicating cushion layers are poured in time. The method can meet the deep foundation pit excavation requirement under the pebble bed red sandstone geological condition, the technical problems that deep foundation pit excavation construction under the existing pebble bed red sandstone geological condition is difficult, cost is high and the construction period is long are solved, the foundation pit excavation speed is increased, safety in the excavation process is guaranteed, and the method has practical guiding significance.

Description

technical field [0001] The invention relates to a construction method for excavating a foundation pit, in particular to a construction method for excavating a deep foundation pit under the geological condition of pebble layer red sandstone. Background technique [0002] A certain project in Lanzhou is a landmark building in Lanzhou and even the entire northwest region. The main building is 250m high, making it the tallest building in the northwest region. The project is located in the bustling area of ​​the city center, adjacent to the city's main road and many residential buildings, and there are many municipal pipelines under the road, so the surrounding environmental protection requirements are relatively high. The area of ​​the foundation pit in the first phase of the project is about 20,100m2, the extension of the surrounding area of ​​the foundation pit is 558m, there are four underground floors, and the deepest excavation depth is 23.6m, which is the deepest foundatio...

AI Technical Summary

Problems solved by technology

In addition, dry and undisturbed red sandstone has high hardness, which is not conducive to excavation. If the dry and undisturbed red sandstone is forcibly excavated, it needs to be broken first before excavation, which will greatly slow down the construction efficiency, prolong the construction period and Increase engineering cost, which also needs to take practical and effective measures to solve this problem

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