温度与粗糙度对能量桩承载特性的影响  

Impact of Temperature and Roughness on Energy Pile Bearing Characteristics

作　　者：冯义[1] FENG Yi(China Railway First Survey and Design Institute Group Co.Ltd,Xi'an,Shaanxi 710043,China)

机构地区：[1]中铁第一勘察设计院集团有限公司,西安710043

出　　处：《铁道工程学报》2024年第12期45-52,共8页Journal of Railway Engineering Society

基　　金：国家自然科学基金面上项目(51679072,51879090,52179101)。

摘　　要：研究目的:浅层地热资源因其清洁和低温特点,受到能源开发的广泛关注。能量桩作为地源热泵技术的关键载体,其开发应用日益受到重视。鉴于温度对桩土界面力学特性的潜在影响,本研究通过不同温度和粗糙度条件下的桩土环剪试验,探讨界面摩擦特性。基于环剪试验结果,提取数值模拟所需参数,并通过接触面模型对能量桩单桩在饱和粉土中的承载力进行数值分析。研究结论:(1)温度升高使桩土界面和粉土的抗剪强度略有下降,且温度对抗剪强度的影响随法向应力增加而递减;(2)通过4种不同法向应力条件下界面抗剪强度的拟合分析,发现内摩擦角在温度升高的情况下会有所减小,但其变化率小于10%;(3)增加接触面粗糙度显著提高抗剪强度,法向应力大于150 kPa时,抗剪强度提升约5%;(4)数值分析显示,温度较低时桩顶应力变化较小,且温度越高越早达到极限承载力,单桩极限承载力随温度升高而下降;接触面粗糙度越大,比例界限荷载越高,粗糙度为100μm相比60μm,提升幅度可达15%;(5)本文研究可为能量桩的应用提供参考。Research purposes:Shallow geothermal resources have attracted widespread attention due to their clean and low-temperature characteristics.As a key carrier of ground source heat pump technology,the development and application of energy piles are increasingly valued.Considering the potential impact of temperature on the mechanical properties of the pile-soil interface,this study investigates interface friction characteristics through ring shear tests under different temperature and roughness conditions.Interface strength parameters were extracted from the test results and used to establish a contact model for numerical analysis of energy pile bearing capacity in saturated silt.Research conclusions:(1)The shear strength of the pile-soil interface and silt slightly decreases with increasing temperature,and the effect of temperature on shear strength reduces as normal stress increases.(2)Through the fitting analysis of the interfacial shear strength under four different normal stress conditions,it is found that the internal friction Angle will decrease under the condition of increasing temperature,but its change rate is less than 10%.(3)Increasing interface roughness significantly improves shear strength,with an enhancement of about 5%under normal stress exceeding 150 kPa.(4)Numerical analysis shows that under lower temperatures,the pile head stress changes less with increasing settlement,and higher temperatures lead to earlier achievement of ultimate bearing capacity,which decreases as temperature rises.Higher roughness results in greater proportional limit load,with a maximum improvement of about 15%when roughness is 100μm compared to 60μm.(5)The research in this paper can provide reference for the application of energy pile.

关 键 词：温度效应 桩-土界面 环剪试验 能量桩 粗糙度 桩土模型 数值分析 

分 类 号：TU4[建筑科学—土工工程]