Low headroom construction case | Ningxia-Hunan ± 800 kV UHV line project

Project Name:Ningxia Zhongning converter station to Hunan Hengyang converter station ± 800 kV UHV DC transmission line project (Hunan 2 bid)

Project Location:Yiyang City, Hunan Province

Project Introduction:The "Ningdian into Hunan Province" project is the Ningxia-Hunan ± 800 kV UHV DC project, which is China's first UHV transmission channel focusing on the development of desert photovoltaic bases and the transmission of new energy, and is a national demonstration project to promote the construction of a new power system and a new energy supply and consumption system, as well as a national demonstration project to promote the large-scale development of wind power and photovoltaic power generation in the "Shagehuang" base and accelerate the construction of a new energy system.

Client:Xiangxiang Gucheng Construction Labor Co., Ltd

Construction Geology:Clay, weathered sandstone, limestone

Construction Equipment:Low headroom 12.9m-SR135SCD00618

Construction drill pipe:Standard φ351×4×9 machine lock drill pipe

Bored pile diameter:φ1.2m、φ1.4m、φ1.8m、φ2.2m、φ2.4m

Bored pile depth:15~19m

Construction Drill Bucket:Pick barrel drill and pick sand bucket with corresponding pile diameter

Construction Difficulties and Solutions:

(1) The road conditions in the mountainous areas are complex, our 135SL equipment can not only be transported with a rod, but also the mast can be disassembled into 12.9m and 13.5m according to the on-site construction conditions, and at the same time, the function of flexible adjustment of the lower mast in the construction of large-diameter pile holes is increased to prevent the drill bucket from colliding with the crawler when rotating and unloading;

(2) There is a solitary stone and sandstone interlayer in the upper part of the pile hole, which has a great challenge to the rock entry ability and stability of the equipment during construction, especially for the pile hole above 2m, it is necessary to first adopt the construction technology of picking the tube drill ring cutting, sleeveing, and then picking the sand bucket fishing.

Construction Efficiency:5~6h into holes, large diameter pile holes need 12~15h