CONSOLIDATION AND CREEP COUPLING MODEL FOR SOFT SOIL CONSIDERING TEMPERATURE EFFECT
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摘要: 软土的固结蠕变是软土地基及构筑物长期变形和稳定性的重要影响因素。在涉热岩土工程兴起和逐渐发展的背景下,研究软土在热力耦合作用下的固结蠕变特性并建立力学模型,对于评估涉热工程软土场地长期变形及稳定性具有重要意义。对此,针对典型滨海软土开展热固结蠕变试验,得到热固结蠕变特性及相关参数取值,建立考虑温度效应的固结蠕变经验公式。结合弹黏塑性理论和热固结理论,推导考虑温度效应的固结蠕变耦合力学模型。在合理性验证基础之上开展算例分析,结果表明:新型热固结蠕变耦合模型能反映土体变形的弹性、塑性、黏性和热胀冷缩属性,能描述土体的热孔压、热回弹和热沉降现象,还能分析软土长期变形的温度效应和时间效应;该成果为软土场地涉热岩土工程问题分析提供了可供参考的理论基础。Abstract: Consolidation and creep of soft soil determine the long-term deformation and stability of soft soil ground and structures on it. With the rise and gradual development of thermal geotechnical engineering, studying the consolidation and creep characteristics of soft soil with thermal-mechanical coupling effect into account and establishing a mechanical model are of great significance for evaluating the long-term deformation and stability of soft soil sites in heat-related engineering. In this regard, combing the existing research results on thermal consolidation and creep of soft soils, some empirical formulas considering the temperature effect are presented. A series of tests about thermal consolidation creep for local soft soils are conducted, and the consolidation creep characteristics of typical soft soils and related parameter values are obtained. On this basis, combined with elasto-visco-plastic theory and thermal consolidation theory, a consolidation-creep coupled mechanical model considering temperature effect is derived and established. The calculation results of examples show that the model can reflect the deformation of elasticity, plasticity, viscosity and thermal expansion. It can describe the thermal excess pore water pressure, thermal rebound and thermal deformation of soil, and it can also analyze the temperature effect and time effect of long-term soil deformation. This research can provide a theoretical basis for the analysis of thermal geotechnical engineering problems in soft soil areas.
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Key words:
- soft soil /
- consolidation /
- creep /
- temperature effect /
- long-term deformation
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图 4 加热温度对软土固结压缩的影响[24]
Figure 4. The influence of heating temperature on the consolidation of soft soil
表 1 试验土样基本物理指标
Table 1. Basic physical properties of test soil
比重 密度
/(g/cm3)含水率
/(%)塑限
/(%)液限
/(%)孔隙比 2.71 1.785 38.4 24.0 39.5 1.10 表 2 土样试验方案
Table 2. Soil sample test program
系列号 土样号 OCR 温度/(℃) 荷载 /kPa 系列1 1-1 1 26(室温) 25~200 1-2 1 36 25~200 1-3 1 46 25~200 1-4 1 56 25~200 系列2 2-1 1 26~56 25~400 2-2 2 26~56 25~400 2-3 4 26~56 25~400 2-4 10 26~56 25~400 表 3 计算参数及其取值
Table 3. Parameters and their values
参数 取值 参数 取值 T0/(℃) 26 αT100/(℃−1) 1.5×10−5 OCR 1 a 0.105 e0 1.10 b 0.15 pc/kPa 95 c 1.0 cv/(×10−4 cm2/s) 6.58 αf/(℃−1) 4.5×10−4 Cc 0.345 αs/(℃−1) 3.0×10−5 Ce 0.045 αst/(℃−1) 3.0×10−5 γ 0.382 nv 0.55 Α 0.0021 mv/MPa−1 0.50 Β 0.0032 ΔT/(℃) 0~30 -
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