Technology for constructing deepwater bridge underwater pier large-diameter bored piles in bead-stringed type karst areas

Abstract

The invention discloses a technology for constructing deepwater bridge underwater pier large-diameter bored piles in bead-stringed type karst areas. A pile foundation of a constructed underwater pier comprises the multiple first bored piles, and the first bored piles all penetrate through a plurality of karst caves successively from top to bottom. The technology includes the steps of (1) numbering the karst caves, (2) grouping the bored piles: dividing the multiple first bored piles into multiple groups according to serial numbers of the karst caves which are penetrated from top to bottom, and enabling the karst caves which are penetrated by all first bored piles in the same groups from top to bottom for the first time to be the same, (3) determining the drilling starting sequence: determining the drilling starting sequence of all first bored piles in the same group in the step (2), and enabling the drilling starting time of the first bored piles, farther away from the middle of the karst cave penetrated for the first time, in the same group to be earlier, and (4) carrying out drilling construction. The technology is simple in step, reasonable in design, low in investment cost, convenient to achieve and good in construction effect, and large-diameter bored pile construction processes can be easily, conveniently and rapidly completed with low cost and high quality.

Description

technical field [0001] The invention belongs to the technical field of bored pile construction in karst areas, and in particular relates to a construction technique for large-caliber bored piles in water piers of deep-water bridges in karst areas. Background technique [0002] With the construction and development of high-speed railways in my country, railway operations have put forward higher requirements for high ride comfort and high safety. Design and construction units must have new innovations in road and bridge foundation settlement control. In the southwestern and southeastern coastal areas of my country, the geological conditions are complex and karst is widespread, but this area is also the main artery of my country's east-west, north-south passage, and the leader of national economic development. In the future, there will be more high-speed railways passing through this area. To form a high-speed rail traffic network from east to west, north to south, so the constr...

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Problems solved by technology

[0003] Nowadays, there are mainly the following defects and deficiencies in the construction of large-diameter and deep-water bridge pile foundations in karst areas: First, in the construction of bridge pile foundations passing through relatively complex karst areas, the design unit did not provide the construction unit with a relatively complete The theoretical basis and construction technical documents are grounded and systematic, and the construction unit crosses the river by feeling the stones. There are many difficult problems and difficulties encountered in the construction; Comprehensiveness and operability; third, for construction projects with high requirements for construction technology and strict standards for bridge foundation settlement, bearing capacity, and stability, the basic theoretical research on pile foundation construction in lava-covered areas is difficult to meet actual construction needs; The provincial boundary Pingshui Super Bridge and Liling Super Bridge in the Hangzhou-Changsha South Section with a design speed of 350km / h are located in areas with strong karst development. The two bridges are only separated by the 274m-long Xiangyun Tunnel. In the karst area of ​​the dark river, the scope is large and the number is large. It is the first case in the history of bridge construction for passenger dedicated lines in China. In the karst-covered area, karst caves and karst fissures, the groundwater is developed, the water permeability is good, the water volume is large, and the geological structure Complex, especially the Liling Super Bridge across the Pingshui River, the river is 180 meters wide, the water depth is 4 to 6 meters, the long-term navigation plan is level Ⅶ, some piles are 90 meters long, and some pile foundations pass through 10 overlapping karst caves. The strength is high and the rock formation is inclined, and the construction is difficult and dangerous when crossing the underground river at the same time. It is very easy to cause the cave to be unstable, collapse and deform, and a little carelessness will cause the drill to be stuck or buried, which will affect the progress of the project; Fourth, to ensure the construction During the construction period, multiple drilling rigs need to be used for simultaneous construction on the same pier. However, since the construction area is a karst area with complex geological structures and underground rivers, there is no domestic precedent for using multiple drilling rigs to construct bored piles on the same pier.

The static pressure chemical grouting method is also not applicable. Although the extra-large karst caves are filled with wet plastic and flow plastic fillings, the effect of this method is better, but because the karst caves are too large and the number is too large, the total amount of grouting cannot be estimated

In summary, although the above two construction methods of bored piles are simple, convenient, safe and easy to control, the economic benefits of input and output are not proportional

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