基于灌注桩试验的多年冻土区桩–土传热过程分析

doi:10.13722/j.cnki.jrme.2019.0903

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摘要为了解多年冻土区灌注桩浇筑后的桩体温度分布特性、变化规律和桩–土传热过程，基于青藏高原北麓河钻孔灌注桩现场实体试验观测结果和理论分析开展系统研究。结果表明：随着混凝土的灌注完成，首先在桩体与周围土体传热过程方面，桩体表现为较为明显的分层现象，多年冻土上限附近以上部分桩体放热热流相对较弱，而以下部分相对较强；其中热流矢量方向以水平为主，深度垂向方向相对很小、且也主要集中于多年冻土上限附近。其次，在温度变化方面，桩体上、下部分表现为不同的温度变化过程。上部经历了快速升温和缓慢的降温过程，而下部表现为较为稳定的降温过程，并由此导致桩体深度方向温度较大的差异性，最大温度梯度达到约11 ℃/m，其中热量主要聚集在桩体上部、并形成高温核。因此，桩底可能存在因温度过低引起的强度不足问题；以及大温差可能导致的沿深度方向混凝土温度裂缝和开裂的产生。工程中建议合理控制入模温度或使用低温早强混凝土，以提高混凝土的养护温度并减少温度裂缝的产生。

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	陈坤1
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	俞祁浩1
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	罗晓晓1
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	陈继3

关键词 ：桩基础, 灌注桩试验, 温度分布, 传热过程, 热流, 高温核

Abstract：In order to study the temperature distribution and variation of piles and the pile-soil heat transfer process after concrete pouring in permafrost regions，a systematic study was carried out based on the observation results of in-situ test and theoretical analysis of cast-in-place piles in Beiluhe of Qinghai—Tibet Plateau. The results show that，with the completion of concrete pouring，the pile body presents an obvious stratification phenomenon in terms of heat transfer between the pile and the surrounding soil. The exothermic heat flow of the pile above the upper limit of permafrost is relatively weak，while the lower part is relatively strong. The direction of the heat flow vector is mainly horizontal and heat flow mainly concentrates near the upper limit of permafrost. In terms of temperature change，the upper and lower parts of the pile body show different temperature change processes. The upper part experiences a rapid heating and slow cooling process while the lower part shows a relatively stable cooling process，which results in a large temperature difference in the depth direction of the pile with a maximum temperature gradient of about 11℃/m. The heat mainly concentrates in the upper part of the pile，forming a high temperature core. Therefore，there may be a problem of insufficient strength due to low temperature at the pile bottom，and large temperature difference along the depth of the pile may lead to temperature cracks in the concrete. In order to raise the curing temperature of concrete and to reduce the generation of temperature cracks in concrete，it is suggested to control the molding temperature reasonably or to use low-temperature early-strength concrete.

Key words： pile foundation')" href="#">

pile foundation cast-in-place pile test temperature distribution process of heat transfer heat flux ')" href="#">high temperature zone

引用本文:

陈坤1，2，俞祁浩1，郭磊1，罗晓晓1，2，陈继3. 基于灌注桩试验的多年冻土区桩–土传热过程分析[J]. 岩石力学与工程学报, 2020, 39(7): 1483-1492.
CHEN Kun1，2，YU Qihao1，GUO Lei1，LUO Xiaoxiao1，2，CHEN Ji3. Analysis of pile-soil heat transfer process based on field test in permafrost regions#br#. , 2020, 39(7): 1483-1492.

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http://rockmech.whrsm.ac.cn/CN/10.13722/j.cnki.jrme.2019.0903 或 http://rockmech.whrsm.ac.cn/CN/Y2020/V39/I7/1483

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