|Table of Contents|

Calculation of safety thickness of underlying filling karst cave roof of bridge pile foundation(PDF)

《建筑科学与工程学报》[ISSN:1673-2049/CN:61-1442/TU]

Issue:
2025年04期
Page:
177-186
Research Field:
岩土工程
Publishing date:

Info

Title:
Calculation of safety thickness of underlying filling karst cave roof of bridge pile foundation
Author(s):
WANG Chengcheng;  ZHANG Shasha;  YANG Xiaohua;  LI Jifu
(School of Highway, Chang'an University, Xi'an 710064, Shaanxi, China)
Keywords:
underlying karst cave;  safety thickness;  bridge pile foundation;  orthogonal test;  multiple regression analysis
PACS:
TU921
DOI:
10.19815/j.jace.2023.05063
Abstract:
When the pile foundation of bridges in mountainous areas has underlying karst cave, the pile foundation should maintain a certain safe thickness with the karst cave to ensure the stability of the pile foundation and bridge. Combined with theoretical analysis and numerical test, the safety thickness of underlying karst cave roof of pile foundation was calculated, and the karst cave roof was simplified into solid supported beam, simple supported beam and cantilever beam respectively. By using FLAC3D software and orthogonal experimental design method, the influence rules and significance of surrounding rock level, karst cave span, height-to-span ratio, pile diameter and rock-socking depth on roof safety thickness were analyzed, and the prediction model of minimum safe roof thickness of underlying karst cave of bridge pile foundation was established. The results show that the safety thickness of underlying karst cave roof of pile foundation is directly proportional to the level of surrounding rock and karst cave span, and inversely proportional to the height-to-span ratio. With the increase of rock-socking depth, the safety thickness of karst cave roof increases first and then decreases, and the influence of pile diameter is not obvious. The overall influence degree from large to small is karst cave span, rock-socking depth, surrounding rock level, pile diameter, height-to-span ratio, and the weight of each factor are 0.679, 0.140, 0.044, 0.018, 0.011, respectively. The test results of engineering cases show that the safety thickness predicted by theoretical analysis is basically consistent with the results of numerical analysis, and the prediction of safety thickness based on mechanical model is conservative, and compared with the mechanical model prediction result, the prediction of safety thickness of two engineering examples by numerical simulation test is reduced by 1.47 m and 0.59 m, respectively. Moreover, the numerical analysis method is feasible when applied to different geological conditions and has certain accuracy and representativeness.

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Last Update: 2025-07-10