应力历史对饱和软土固结系数的影响

王江锋; 袁威; 何况; 郑培信

doi:10.3799/dqkx.2020.184

应力历史对饱和软土固结系数的影响

doi: 10.3799/dqkx.2020.184

王江锋^1, ,,
袁威¹,
何况²,
郑培信³

1.
华北水利水电大学地球科学与工程学院, 河南郑州, 450045
2.
郑州地铁集团有限公司, 河南郑州, 450046
3.
河南省尧栾西高速公路建设有限公司, 河南郑州, 450046

基金项目:

国家自然科学基金资助项目 U1704243

详细信息

作者简介:
王江锋(1976-), 男, 博士, 副教授, 从事隧道与地下工程、岩土加固与测试等方面的科研与教学工作.ORCID:0000-0003-0029-9324.E-mail:398909366@qq.com

中图分类号: P642
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出版历程
- 收稿日期: 2020-05-27
- 刊出日期: 2020-12-15

Influence of Stress History on Consolidation Coefficient of Saturated Soft Soil

1.
College of Earth Sciences and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
2.
Zhengzhou Metro Group Co., Ltd., Zhengzhou 450046, China
3.
Henan yaoluanxi Expressway Construction Co., Ltd., Zhengzhou 450046, China

摘要

摘要: 为了探究不同固结状态下的饱和软土固结系数的变化规律，在太沙基固结理论的基础上，利用渗透系数和孔隙比的关系、孔隙比和固结应力的关系，分别推导出了在正常固结和超固结状态下固结系数（C_v）随固结应力变化的关系式，将关系式代入Terzaghi方程，进而获得考虑应力历史和固结应力影响的修正Terzaghi一维固结方程；通过室内固结试验和工程应用分析对固结系数关系式和修正的Terzaghi一维固结方程的准确性进行验证.结果表明，对于正常固结的软土，当固结应力小于前期固结应力时，固结系数随应力的增大而增大；当固结应力大于前期固结应力时，固结系数随应力的增大而减小.对于超固结状态的软土，固结系数随应力的增大而增大，最后趋于平缓.当上覆荷载较小时，修正前后的Terzaghi一维固结方程计算结果相近；但当上覆荷载较大时，修正后的Terzaghi一维固结方程计算的固结度明显滞后于修正前的计算结果.前期的应力历史和后期的固结应力对软土固结系数的影响是不容忽视的，修正后的Terzaghi一维固结方程更能真实反映土体的固结性状.
- 饱和软土 /
- 固结系数 /
- 前期固结应力 /
- 应力历史 /
- 超固结比 /
- 工程地质
Abstract: To explore the changing law of the consolidation coefficient of saturated soft soil under different consolidation states, based on Terzaghi's consolidation theory, using the relationship between permeability coefficient and void ratio, void ratio, and consolidation stress, the relationship between consolidation coefficient (C_v) and consolidation stress under normal consolidation and over consolidation is derived. The modified Terzaghi one-dimensional consolidation equation considering the influence of stress history and consolidation stress is obtained by substituting the relationship into the Terzaghi equation; The accuracy of the consolidation coefficient relation and the modified Terzaghi one-dimensional consolidation equation were verified by laboratory consolidation test and engineering application analysis. When the consolidation stress is larger, the results show that for normally consolidated soft soil when the consolidation stress is less than the previous consolidation stress, the consolidation coefficient increases with the increase of stress. When the consolidation stress is larger than the previous consolidation stress, the consolidation coefficient decreases with the increase of the stress. For over consolidated soft soil, the coefficient of consolidation increases with the increase of stress and finally tends to be gentle. When the load is small, the calculation results of the Terzaghi one-dimensional consolidation equation before and after the modification are similar; but when the load is large, the consolidation degree of the corrected Terzaghi one-dimensional consolidation equation lags significantly behind the calculation result before the modification. The influence of the previous stress history and the later consolidation stress on the consolidation coefficient of soft soil can not be ignored. The modified Terzaghi one-dimensional consolidation equation can more truly reflect the consolidation behavior of soil.
- saturated soft soil /
- consolidation coefficient /
- preconsolidation stress /
- stress history /
- over consolidation ratio(OCR) /
- engineering geology

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图 1 正常固结土孔隙比与固结应力之间的关系

Fig. 1. Relationship between porosity ratio of normal consolidated soil and vertical stress

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图 2 超固结土孔隙比与固结应力之间的关系

a.σ₀≤σ₀+Δσ≤σ_c; b.σ₀+Δσ≥σ_c

Fig. 2. Relationships between porosity ratio of over consolidated soil and vertical stress

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图 3 本文试样正常固结时C_v-σ’关系

Fig. 3. C_v-σ' diagram for normal consolidation of samples in this paper

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图 4 本文试样超固结时C_v-σ’关系

Fig. 4. C_v - σ' diagram for over consolidation of samples in this paper

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图 5 林鹏等(2003)试样正常固结时C_v-σ’关系

Fig. 5. C_v-σ' diagram for normal consolidation of samples by Lin et al.(2003)

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图 6 林鹏等(2003)试样超固结时C_v-σ’关系

Fig. 6. C_v- σ' diagram for over consolidation of samples by Lin et al.(2003)

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图 7 模型简化图

Fig. 7. Simplified diagram of model

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图 8 不同荷载下固结度与时间关系曲线

a.正常固结; b.超固结

Fig. 8. Relationships between degree of consolidation and time under different loadings

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图 9 不同荷载下沉降与时间关系曲线

a.正常固结; b.超固结

Fig. 9. Relationship between settlement and time under different loadings

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表 1 土的物理力学性质指标

Table 1. Physical and mechanical properties of soil

天然重度(kn/m³)	含水率(%)	塑性指数(%)	液限(%)	黏粒含量(%)	孔隙比	压缩指数	回弹指数
16.95	46.42	25.27	58.38	70.7	1.19	0.46	0.06

下载: 导出CSV

表 2 试验方案

Table 2. Testing plans for consolidation test

固结状态	试样编号	加载路径(kPa)及持续时间
正常固结	1，2	25(1 d)→50(1 d)→100(1 d)→150(1 d)→0→50(60 min)
	3，4	25(1 d)→50(1 d)→100(1 d)→150(1 d)→0→100(60 min)
	5，6	25(1 d)→50(1 d)→100(1 d)→150(1 d)→0→150(60 min)
	7，8	25(1 d)→50(1 d)→100(1 d)→150(1 d)→0→200(60 min)
	9，10	25(1 d)→50(1 d)→100(1 d)→150(1 d)→0→400(60 min)
	11，12	25(1 d)→50(1 d)→100(1 d)→150(1 d)→0→800(60 min)
超固结	13，14	25(1 d)→50(1 d)→100(1 d)→200(1 d)→400(1 d)→800(1 d)→0→50(60 min)
	15，16	25(1 d)→50(1 d)→100(1 d)→200(1 d)→400(1 d)→800(1 d)→0→100(60 min)
	17，18	25(1 d)→50(1 d)→100(1 d)→200(1 d)→400(1 d)→800(1 d)→0→150(60 min)
	19，20	25(1 d)→50(1 d)→100(1 d)→200(1 d)→400(1 d)→800(1 d)→0→200(60 min)
	21，22	25(1 d)→50(1 d)→100(1 d)→200(1 d)→400(1 d)→800(1 d)→0→400(60 min)
	23，24	25(1 d)→50(1 d)→100(1 d)→200(1 d)→400(1 d)→800(1 d)→0→800(60 min)

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