Combined Excavation Method of Layered Stairs for Deep Foundation Pit in Wide Shallow Valley and Deep Foundation Pit with Thick Covering Layer of Sand and Pebble

Abstract

The invention relates to a deep foundation pit layered ladder section combined excavation method of a wide shallow river valley with a sand gravel thickness coverage layer. The method is characterizedin that a drainage ditch, a water collecting well and a water precipitation well are arranged at an inner part of a foundation pit before a sand gravel layer is excavated, and an elevation adjustingbody and an energy dissipation groove are arranged at a joint of the drainage ditch and the water collecting well; layered thickness and a partition position of the sand gravel layer are determined firstly, then layered partition excavation is carried out, and then a mortar protective layer is sprayed on a slope surface; layered loose blasting is sprayed on a rock stratum from top to bottom, and pre-crack blasting is adopted on the side slope part, a blasting working groove is arranged inside the protective layer, a horizontal main blasting hole and a horizontal auxiliary blasting hole are synchronously drilled, and then smooth blasting is carried out; a concrete cushion layer is immediately applied after the rock stratum is excavated; and finally a transverse reinforcement body, a transverse drainage body and a plain concrete layer are arranged on the slope of the foundation pit. According to the method, the cost of drainage of the foundation pit and a construction channel can be saved. the field construction efficiency and quality can be improved as well, and the influence on the surrounding environment can be further reduced.

Description

technical field [0001] The present invention relates to a large-scale deep foundation pit excavation construction method, in particular to a layered step combination excavation construction of a large deep foundation pit with a thick covering layer of sand and pebbles on the upper part and a thick covering layer of sand and pebbles on the lower part of a shallow river valley. The method belongs to the field of civil engineering and is suitable for large-scale deep foundation pit excavation projects with large foundation pit depth and complex geological conditions. Background technique [0002] For the construction of large-scale deep foundation pits in rainy areas, it is often necessary to take various measures to improve the stability of the foundation pit, such as rationally setting the foundation pit slope support structure, dewatering the engineering foundation pit according to local conditions, and adjusting the slope ratio of the foundation pit, etc. The implementation...

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Problems solved by technology

[0003] At present, the deep foundation pit construction technology carried out by engineering circles under the geological conditions of thick sandy pebbles and weakly weathered siltstone has achieved good engineering construction results under suitable working conditions, but how to systematically strengthen the division and block, There are few researches on construction techniques such as rapid drainage of water inside the foundation pit and directional micro-blasting, especially in terms of systematically considering the connection between various construction techniques, reducing the impact of blasting construction on foundation pits and cofferdams, and quickly closing the excavation surface of foundation pits. technology is not yet mature

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