A method for constructing a continuous bearing layer of ultra-long rock-socketed piles in beaded karst areas

Abstract

The invention discloses a constructing method for a continuous bearing layer of a super long socketed pile in a bead-like karst area. The constructing method comprises the following steps that S1, thedesign elevation of each pile is optimized and determined through detailed exploration of one pile with multiple holes; S2, a plurality of vertical steel pipes is evenly pre-embedded on each pile body along the pile circumference; S3, the bottom of each pile is subjected to core-taking and additional exploration by using steel pipe passages, and whether soft layers are at the bottom of each pileor not and the specific distribution of the soft layers are determined combined with the detailed exploration; S4, cutting, broaching and cleaning of the soft layers are completed in the force bearingrange of the bottoms of the piles; S5, the soft layers in the force bearing range of the bottoms of the piles are replaced; S6, orifice slurry supplying is performed; and S7, orifice shut-off pressure grouting is performed. By the thought and method that the continuous bearing layer is actively introduced and constructed at the bottoms of the piles in the design process, the selection range of the elevation of the bearing layer of the pile ends is expanded, the design is effectively optimized, and the designed pile length is shortened; and through the integrated process such as high pressurecutting, cleaning and double fluid grouting, the continuous bearing layer is formed, and the potential quality safety hazards of the socketed pile bottom are actively eliminated.

Description

technical field [0001] The invention relates to the technical fields of municipal road and bridge engineering and geotechnical engineering, in particular to a method for constructing a continuous bearing layer of ultra-long rock-socketed piles in beaded karst areas. Background technique [0002] 1. The distribution of karst caves in the beaded karst area is extremely complex and the selection of pile lengths for long-span bridge piles: [0003] The geological conditions in many areas in the south of China are complex, with severe rock surface undulation, strong and weak inclusions, and karst development. In addition to the development of joints and fissures in the bedrock, there are also many broken or weak interlayers; the development of karst is mainly manifested as dissolution, tooth shoots, stalactites, karst ditches, karst troughs, karst caves, underground rivers, etc., and the plane of karst caves can be dotted , reticular, sheet-like, and can develop into a continuou...

AI Technical Summary

Problems solved by technology

A multi-hole survey is necessary first, but it can only be done to find out the general trend and range of the karst caves in the pile foundation in terms of plane and vertical distribution.

[0006] 2. The construction of long-span and super-long bridge piles in the beaded karst area is extremely risky and complicated, and there are uncertainties such as construction delays:

The above methods are cumbersome, difficult and cost more people, money, materials and construction period in construction operation.

In practice, the final number of survey holes for some engineering single piles has even been intensified from 2 to 4 holes in the design stage to 8 to 9 holes; more importantly, the length of bridge piles in areas where beaded karst is strongly developed generally reaches about 40m, and can even be Up to 70-100m, long reconnaissance holes or advanced drilling are not only difficult and time-consuming to construct, but also prone to plane deviation and string holes due to excessive slenderness ratio of drill pipes; There are disputes over the subject of implementation, identification of pile foundation quality grades, and the subject of responsibility for problems. Moreover, if the supervisory inspection is passively carried out by the competent department or an independent third party, affected by the inspection frequency, root number restrictions, and random selection methods, overall still There is a possibility that some pile foundations with problems in the bearing layer at the bottom of the pile are missed and have not been tested

Images