高烈度地震设防区巨厚堆积体锚碇深基坑稳定性研究

杜兆萌; 刘天翔; 伍运霖; 雷航; 李超; 袁文

doi:10.20265/j.cnki.issn.1007-2993.2024-0092

高烈度地震设防区巨厚堆积体锚碇深基坑稳定性研究

doi: 10.20265/j.cnki.issn.1007-2993.2024-0092

杜兆萌^1,,
刘天翔^1, ,,
伍运霖¹,
雷航¹,
李超²,
袁文²

1.
四川省公路规划勘察设计研究院有限公司，四川成都　610041
2.
四川省交通建设集团股份有限公司，四川成都　610041

基金项目: 四川省交通运输科技项目（2024-A-04；2023-A-02）；四川省科技计划（2022YFG0141）；四川省公路规划勘察设计研究院有限公司科研项目（KYXM2021000049；KYXM2022000038；KYXM2024000109）

详细信息

作者简介:
杜兆萌，女，1995年生，硕士，工程师。研究方向：特殊支挡结构设计。E-mail：473453892@qq.com

通讯作者:
刘天翔，男，1980年生，硕士，正高级工程师。研究方向：公路地质灾害防治设计与监测预警。E-mail：411495191@qq.com

中图分类号: TU473
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出版历程
- 收稿日期: 2024-03-01
- 录用日期: 2024-05-09
- 刊出日期: 2025-10-10

Stability of deep foundation pit anchored by thick accumulation in high intensity earthquake area

1.
Sichuan Highway Planning, Survey, Design and Research Institute Ltd., Chengdu 610041, Sichuan, China
2.
Sichuan Transportation Construction Group Co., Ltd., Chengdu 610041, Sichuan, China

摘要

摘要: 锚碇基坑的稳定性是影响悬索桥工程安全的主要控制因素。四川某特大悬索桥位于高烈度地震设防区，其锚碇基坑位于巨厚堆积体中，基坑边坡最大坡高达110 m。以该锚碇基坑工程为例，针对巨厚层堆积体上超百米深基坑的长期稳定性问题开展研究。采用原位密度试验、现场剪切试验及变形试验，研究基坑土体强度及变形特性，得出了基坑土体物理力学参数。应用有限差分软件对锚碇基坑进行地震三维模拟计算，结果表明在强震下深厚堆积体基坑极易诱发变形甚至滑移失稳破坏，坡体最大位移约20 m，坡体失稳范围厚度约15～23 m。据此，提出桥梁基坑防护两水准要求以及开挖预加固、分步开挖、分区防护的综合治理措施，在此基础上采用动力时程分析法进行基坑稳定性验算。结果表明，在输入30 s汶川地震波后加固后的坡体最大位移仅为0.223 m。基坑开挖支护完成后连续36个月的监测数据显示坡体最大位移量小于9.05 mm，与数值计算结果基本吻合，验证了加固措施和数值计算方法的有效性。
- 边坡稳定性 /
- 动力时程分析 /
- 数值计算 /
- 基坑 /
- 堆积体
Abstract: The stability of anchor foundation pit is the main control factor affecting the safety of suspension-bridge engineering. A suspension-bridge in Sichuan is located in a high-intensity earthquake area, which anchorage foundation pit is located in thick accumulation. The maximum slope height of the foundation pit slope is 110 meters. Taking the anchorage foundation pit project as an example, research is conducted on the long-term stability of a foundation pit over 100 meters deep on a thick accumulation. By conducting in-situ density tests, on-site shear tests, and deformation tests, the strength and deformation characteristics of the foundation pit soil were studied, and the physical and mechanical parameters of the foundation pit soil were obtained. The application of finite difference software for seismic simulation calculation of anchor foundation pit shows that deep accumulation foundation pit is prone to deformation and even sliding instability and failure under strong earthquakes. The maximum displacement of the slope is about 20 m, and the thickness of the slope instability range is about 15~23 m. Based on this, the two-level requirements for bridge foundation pit protection and comprehensive treatment measures of excavation pre-reinforcement, step-by-step excavation, and zoning protection are proposed. The dynamic and time-historical analysis method was used to verify the stability of the foundation pit under this treatment measure. The results show that the maximum displacement of the reinforced slope after 30 seconds of Wenchuan earthquake wave input was only 0.223 m. The monitoring data for 36 consecutive months after the excavation and support of the foundation pit show that the maximum displacement of the slope was less than 9.05 mm, which was basically consistent with the numerical calculation results, verifying the effectiveness of the reinforcement measures and numerical calculation methods.
- slope stability /
- dynamic time history analysis method /
- numerical calculation /
- foundation pit /
- accumulation

HTML全文

图 1 锚碇基坑开挖边坡典型剖面

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图 2 剪切试验装置

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图 3 计算模型

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图 4 基坑开挖完成时位移及其矢量图

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图 5 基坑开挖完成时塑性区分布

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图 6 基坑开挖完成后剪应变增量及稳定系数

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图 7 动力时程分析三维模型

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图 8 深基坑支护措施模型

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图 9 震后基坑位移及其矢量图

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图 10 基坑及边坡防护全景图

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图 11 第11级边坡后缘位移–时间曲线

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表 1 剪切试验结果^[19]

试点编号	含水状态	σ/MPa	τ/MPa	tan φ	c/kPa
1	天然	0.75	0.49	0.47	128
2	天然	1.00	0.57
3	天然	0.25	0.24
4	天然	0.51	0.42
5	泡水10 h	0.73	0.50	0.44	88
6	泡水10 h	1.01	0.57
7	浸水	0.25	0.19
8	浸水	0.50	0.30

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表 2 变形试验结果^[19]

试点编号	距洞口位置/m	最大应力 /MPa	变形模量 /MPa	弹性模量 /MPa	备注
1	15.8	1.0	149.76	338.15	天然
2	19	1.0	328.16	579.69	浸水湿润
3	23	1.0	696.39	886.58	天然

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表 3 各区域土层的物理力学参数

区域	弹性模量 /MPa	泊松比	黏聚力 /kPa	内摩擦角 /(°)	重度 /(kN·m⁻³)
Q₄^col+dl含砾黏土	300	0.35	125	24	23
Q₄^col+dl碎石土	500	0.33	100	28	23
Q₃^h碎石土	600	0.31	115	33	24
Q₃^h块石土	800	0.3	110	35	24

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