岩溶陡坡地区公路桥梁桩基极限承载力研究

摘要:

岩溶和陡坡是影响桩基础极限承载力的关键因素。为研究在不良地质条件下桩基础极限承载力影响因素和防治措施，利用有限元软件建立了桩基础模型并依据相关规范验证了其有效性，针对5种不同坡度和4种岩溶顶板厚度进行了正交模拟试验，分析了不同工况下桩基承载力的变化和桩体承载形式。结果表明：溶洞会造成更大的沉降，地基沉降与岩溶顶板厚度呈反比，3倍桩径为岩溶地质对桩基的最大影响范围。大于45°的陡坡会造成更大的地基沉降进而减少桩基的极限承载力，应极力避免坡度45°以上的陡坡在实际工程中的使用，无法避免时，应重点考虑其对桩基承载力的影响。溶洞和陡坡降低桩体极限承载力的方式主要表现为降低桩体侧摩效应，桩体承载形式由摩擦桩转变成端承桩。

Abstract:

Lava and steep slopes are the key factors affecting the ultimate bearing capacity of pile foundations. In order to study the influencing factors and prevention measures of the ultimate bearing capacity of the pile foundation under adverse geological conditions, the pile foundation model was established by using finite element software and its effectiveness was verified according to the relevant specifications. Orthogonal simulation test is carried out to analyze the change of the bearing capacity of the pile foundation and the bearing form of the pile under different working conditions. The results show that the karst cave will cause greater settlement, the foundation settlement is inversely proportional to the thickness of the lava roof, and 3 times the pile diameter is the largest influence range of the lava geology on the pile foundation. The steep slope greater than 45 °will cause greater foundation settlement and reduce the ultimate bearing capacity of pile foundation. We should try our best to avoid the use of steep slope above 45 °in practical engineering. When it is unavoidable, we should focus on considering its influence on the bearing capacity of pile foundation. Karst caves and steep slopes reduce the ultimate bearing capacity of piles mainly by reducing the lateral friction effect of piles, and the bearing form of piles is changed from friction piles to end-bearing piles.