巨型溶洞区深厚填筑体长期变形特性试验研究

苏芮; 苏谦; 贺琛方; 董敏琪; 王迅; 郑余朝

doi:10.3969/j.issn.0258-2724.20220642

巨型溶洞区深厚填筑体长期变形特性试验研究

doi: 10.3969/j.issn.0258-2724.20220642

西南交通大学土木工程学院，四川成都，610031

基金项目: 国家自然科学基金项目（51978588）

详细信息

作者简介:
苏芮（1994—），博士研究生，研究方向为交通土建病害治理，E-mail：594122895@qq.com

通讯作者:
苏谦（1972—），教授，博士研究生导师，研究方向为交通土建病害治理，E-mail：suqian@126.com

中图分类号: U25
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- 被引次数: 0
出版历程
- 收稿日期: 2022-09-19
- 修回日期: 2023-07-02
- 网络出版日期: 2024-09-05

Experimental Study on Long-Term Deformation Characteristics of Deep and Thick Fills in Giant Karst Cave

School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China

摘要

摘要:
为探讨不同深度位置溶洞回填体与天然堆积层的沉降和应力随时间的变化规律，以成贵铁路玉京山隧道大型溶洞回填工程为原型，开展1∶100的室内离心模型试验，对溶洞大厅底部不均匀天然软弱堆积层长期变形规律进行分析，采用粒径小于2 mm的河沙模拟废弃洞渣回填体，使用川西黏土模拟溶洞底部软土层，并用现场监测结果验证室内试验可靠性. 研究结果表明：施工结束后1.5年，溶洞回填体变形基本达到稳定状态，且变形量约为总沉降量的86.9%；软土层的变形是隧道底部土体变形的主要组成部分，其变形量约占总沉降的87.5%；隧底沉降量与底部软土层厚度成正相关，并且当软土层厚度小于12.5 cm时，软土层厚度对隧道底部沉降影响较小；模型试验沉降变形与现场监测结果相差为3.83%，表明本文所开展试验能够反映出隧道底部土体长期变形特性.
- 深厚填筑体 /
- 长期变形 /
- 离心模型试验 /
- 软土层不均 /
- 现场监测
Abstract:
In order to explore the variation of settlement and stress of the karst cave backfill and natural accumulation layer at different depths, a giant karst cave backfill project in the Yujingshan tunnel of Chengdu—Guiyang railway was studied. A 1∶100 laboratory centrifugal model test was carried out to analyze the long-term deformation law of the inhomogeneous natural soft accumulation layer at the bottom of the karst cave, in which the river sand with a particle size of less than 2 mm was used to simulate the karst cave backfill, and the western Sichuan clay was used to simulate the soft soil layer at the bottom of the karst cave. The reliability of the laboratory test was verified by field monitoring results. The results show that the deformation of the karst cave backfill basically reaches a stable state within 1.5 years after the termination of construction, and the deformation is about 86.9% of the total settlement; the deformation of the soft soil layer is the main component of the soil deformation at the bottom of the tunnel, and its deformation accounts for about 87.5% of the total settlement. The settlement at the bottom of the tunnel is positively correlated with the thickness of the soft soil layer, and when the thickness of the soft soil layer is less than 12.5 cm, it has less influence on the settlement at the bottom of the tunnel. The difference in settlement deformation between the model test and the on-site monitoring is only 3.83%, indicating that the experiments conducted in this article can reflect the long-term deformation characteristics of the soil at the bottom of the tunnel.
- deep and thick fills /
- long-term deformation /
- centrifugal model test /
- inhomogeneous soft layer /
- on-site monitoring

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图 1 巨型溶洞大厅现场

Figure 1. Scene of giant karst cave

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图 2 隧道与溶洞大厅相对位置平面示意（单位：m）

Figure 2. Relative position of tunnel and karst cave (unit: m)

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图 3 溶洞回填横断面

Figure 3. Backfill section of karst cave

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图 4 特征横断面（单位：m）

Figure 4. Feature section (unit: m)

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图 5 TLJ-2型土工离心机

Figure 5. TLJ-2 geotechnical centrifuge

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图 6 模型断面（单位：m）

Figure 6. Model section (unit: m)

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图 7 沉降与土压力测点分布示意（单位：m）

Figure 7. Settlement and earth pressure measuring point distribution (unit: m)

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图 8 沉降板

Figure 8. Settlement plate

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图 9 插入模型桩

Figure 9. Insertion of model pile

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图 10 位移计固定装置

Figure 10. Displacement meter fixing device

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图 11 累计沉降随时间变化曲线

Figure 11. Changes of cumulative settlement with time

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图 12 土压力随时间变化曲线

Figure 12. Changes of earth pressure with time

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图 13 不同软土层厚度下软土层净沉降曲线

Figure 13. Net settlement curves of soft soil layer with different thicknesses

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图 14 加固后松散堆积体变形曲线

Figure 14. Deformation curves of loose accumulation body after reinforcement

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图 15 不同软土层厚度下各深度测点沉降对比

Figure 15. Comparison of settlement at different depth measuring points under different soft soil thicknesses

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图 16 试验前后模型表面对比

Figure 16. Comparison of model surface before and after test

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图 17 现场实测沉降和室内试验测试值对比

Figure 17. Comparison of measured settlement and laboratory test values

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表 1 离心模型试验相似常数（原型/模型）

Table 1. Similar constants in centrifugal model test (prototype/model)

物理量	相似比	物理量	相似比
长度	100∶1	密度	1∶1
面积	10⁴∶1	孔隙比	1∶1
体积	10⁶∶1	饱和度	1∶1
含水量	1∶1	重度	1∶100
应力	1∶1	应变	100∶1
泊松比	1∶1	弹性模量	1∶1
内摩擦角	1∶1	时间	10⁴∶1

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表 2 工程现场各类土体物理力学参数

Table 2. Physical and mechanical parameters of various soil in site

土层名称	密度/ （g·cm⁻³）	黏聚力/kPa	内摩擦角/（°）	基本承载力/kPa	压缩模量/MPa
废弃洞渣	2.20	0	36.0	280.00	27.0
软塑状黏土	1.86	17.00	7.0	100.00	4.2
碎石土	2.30	0	38.0	400.00	65.0

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表 3 试验河沙物理力学特性参数

Table 3. Physical and mechanical properties of river sand in tests

参数	干密度/（g·cm⁻³）	含水量/%	内摩擦角/（°）	黏聚力/kPa	压缩模量/MPa	最大孔隙比	最小孔隙比
数值	1.79	23.00	35.50	0	27.0	0.67	0.35

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表 4 试验黏土物理力学特性参数

Table 4. Physical and mechanical properties of experimental clay

参数	最大干密度/ （g·cm⁻³）	最优含水量/%	液限/%	塑限/%	内摩擦角/（°）	黏聚力/kPa	干密度/（g·cm⁻³）	含水量/%	压缩模量/MPa
数值	1.80	15.30	31.00	13.00	7.30	16.20	1.46	27.00	4.2

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表 5 试验前后各土层参数比较

Table 5. Comparison of parameters of each soil layer before and after test

土层	试验前后	密度/（g·cm⁻³）	含水量/%	孔隙比
废弃洞渣模拟层	试验前	2.200	23.000	0.410
废弃洞渣模拟层	试验后	1.880	5.000	0.400
软土层	试验前	1.850	27.000	0.780
软土层	试验后	1.610	10.000	0.440

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