海底峡谷浊流汇流后含沙量与速度变化研究

张子涵; 任宇鹏; 陶威; 许国辉; 靳梓堃

doi:10.16562/j.cnki.0256-1492.2023032301

海底峡谷浊流汇流后含沙量与速度变化研究

1.
中国海洋大学海洋环境与生态教育部重点实验室，青岛 266100

2.
山东省海洋环境地质工程重点实验室，青岛 266100

基金项目: 国家自然科学基金“海底峡谷弱稳定沉积物推动式剪切破坏传播及其对沉积地层的影响”（42206055）， “风暴浪作用下海底高浓度含沙层形成过程的观测研究”（41976049）

详细信息

作者简介: 张子涵（1998—），女，硕士研究生，从事海洋工程地质研究，E-mail：zihanzhang513@163.com

通讯作者: 许国辉（1972—），男，博士，教授，主要从事海洋工程地质研究，E-mail：xuguohui@ouc.edu.cn

中图分类号: P736

收稿日期: 2023-03-23

修回日期: 2023-11-27

刊出日期: 2024-08-28

Variations in sediment concentration and velocity after turbidity current confluence in submarine canyon

1.
Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China

2.
Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Qingdao 266100, China

More Information

Corresponding author: XU Guohui, xuguohui@ouc.edu.cn

Received Date: 23 March 2023

Revised Date: 27 November 2023

Publish Date: 28 August 2024

摘要

摘要:
高速的浊流具有强大的破坏力，威胁着海底结构物的安全。海底峡谷是浊流向深海运动的重要通道，其中许多海底峡谷具有多条分支峡谷，而分支峡谷与主干峡谷浊流发生汇流后，含沙量、速度可能会增加，进而破坏力增强。本文通过室内水槽试验和数值模拟，研究了分支峡谷中的浊流汇流到主干峡谷中含沙量和速度的变化，并与仅有主干峡谷浊流的情景进行了对比。研究发现，发生汇流时，浊流的高度、含沙量和速度在头部均有增加，在汇流发生过后会有所减小，但含沙量和速度仍大于不发生汇流时的情况。本文试验结果可为有分支峡谷发生浊流汇流的现场监测位置及项目、速度推算提供指引。
- 海底峡谷 /
- 浊流 /
- 汇流 /
- 速度 /
- 含沙量
Abstract:
High-speed turbidity currents are very destructive and threaten the safety of seabed constructions. An important channel for turbidity currents to move to the deep sea is submarine canyons, of which many have multiple branches. Once a branch meets the canyon with turbidity currents, the sand content and the velocity of turbidity currents could be increased, and so the destructive power. We studied the changes in sand content and movement velocity of turbidity currents in branch canyons converging into the main canyon, to which the scenario of turbidity currents in main-canyon-only was compared. Result show that the height, sand content and velocity of turbidity currents were increased at the head when confluence occurred, and decreased after the confluence occurred. However, the sand content and the velocity were still larger than those without confluence. This study provided guidelines for site selection and velocity calculation for field monitoring when turbidity currents confluence occurs in branch canyons.
- submarine canyons /
- turbidity currents /
- confluence /
- velocity /
- sediment concentration

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图 1 海底峡谷汇流模型概况图

Figure 1.

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图 2 取样盒示意图

Figure 2.

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图 3 试验土样的粒度级配曲线

Figure 3.

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图 4 总含沙量随初始配置浊流含沙量的变化

Figure 4.

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图 5 主流和汇流情景下浊流各层含沙量随初始浊流含沙量的变化

Figure 5.

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图 6 数值模拟模型构建

Figure 6.

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图 7 初始含沙量为200 g/L的浊流模拟流速与实测流速对比

Figure 7.

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图 8 浊流在取样点S₁、S₂处的垂向速度剖面

Figure 8.

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图 9 200 g/L的浊流在主流情景时的模拟结果

Figure 9.

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图 10 浊流运动中的头部流场（x方向）图

Figure 10.

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表 1 试验浊流初始含沙量配置表

Table 1. Configuration in initial sand content in the turbidity current experiment

序号	试验情景	浊流含沙量/(g/L)
序号	试验情景	主流	支流
1	主流	100	0
2	汇流	100	100
3	主流	200	0
4	汇流	200	200
5	主流	300	0
6	汇流	300	300
7	主流	400	0
8	汇流	400	400
9	主流	500	0
10	汇流	500	500

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表 2 含沙量样品编号与取样盒层位对应关系

Table 2. Correspondence between sand content sample serial number and sampling box layer

取样盒分层名称	距底高度范围/cm	S₁处各层样品编号	S₂处各层样品编号
上层	8～12	S1-3	S2-3
中层	4～8	S1-2	S2-2
底层	0～4	S1-1	S2-1

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表 3 初始含沙量为200 g/L的浊流模拟流速最大值与试验流速最大值对比

Table 3. Comparison between the maximum simulated currents velocity and the maximum experimental flow velocity for turbidity flow with initial sand content of 200 g/L

项目	主流情景 v_A点	主流情景 v_B点	汇流情景 v_A点	汇流情景 v_B点
试验值/(m/s)	0.275	0.304	0.306	0.356
模拟值/(m/s）	0.270	0.291	0.305	0.351
绝对误差/(m/s)	0.005	0.013	0.001	0.006
相对误差/%	1.91	4.42	0.42	1.63
注：相对误差的计算方法为相对误差=$ \dfrac{\|{\text{模拟值}}-{\text{试验值}}\|}{\text{试验值}}$。

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