Construction technology of large-diameter bored piles for underwater piers of deep-water bridges in beaded karst areas

Abstract

The invention discloses a construction technology of large-caliber bored piles for deep-water bridges in deep-water bridges in karst areas. Passing through multiple karst caves successively, including the steps: 1. Numbering of karst caves; 2. Grouping of bored piles: dividing multiple first bored piles into multiple groups according to the numbers of the karst caves crossed from top to bottom, and the same group of bored piles All the first bored piles in the pile pass through the same karst caves from top to bottom for the first time; 3. Determination of the drilling sequence: check the drilling sequence of all the first bored piles in the same group of bored piles in step 2. Definitely; in the same group of bored piles, the farther the first bored pile from the middle part of the first crossing of the karst cave is, the earlier the drilling time will be; 4. Drilling construction. The invention has simple process steps, reasonable design, low investment cost, convenient realization, good construction effect, and can complete the construction process of large-diameter bored piles simply, quickly, at low cost and with high quality.

Description

Technical field [0001] The invention belongs to the technical field of bored pile construction in karst areas, and particularly relates to a large-diameter bored pile construction technology for underwater piers of deep-water bridges in beaded 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 smoothness and high safety. Design and construction units must have new innovations in the settlement control of road and bridge foundations. In the southwest and southeast coastal areas of China, the geological conditions are complex and karsts are widespread. However, this area is the main artery of China’s east, west, south and north channels and the leader of the country’s economic development. In the future, there will be more high-speed rail crossings in this area. A high-speed rail transportation network is formed, so large-diameter, deep-water bridge p...

AI Technical Summary

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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