Study on flow and sediment dynamics and deposition characteristics of hollow block
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摘要: 空心块体具有良好的阻水和促淤功能，近年来被广泛用于生态修复工程。本文结合水槽试验及Flow-3D数值模拟，分析了开敞型和半封闭型空心块体的阻水效应和泥沙淤积特性。结果表明：空心块体的开孔率对内部水流流速、紊动强度起主导作用，开孔率较小的半开敞型空心块体减速、制紊效果更强；开敞型和半封闭型空心块体近底层悬沙浓度分别增大56%和75%，两者均有利于促进泥沙在块体内部淤积，近底层水流紊动越强，泥沙淤积形态差异越大；空心块体所营造的低流速、泥沙微淤、内外连通的水沙环境是大型底栖生物的生境需求，半封闭型空心块体内部的低紊动水流结构更有利于大型底栖生物的栖息、繁衍。Abstract: Hollow blocks have good water blocking and siltation promotion functions, and have been widely used in ecological restoration projects in recent years. In this paper, combined with flume experiment and Flow-3D numerical simulation, the water blocking effect and sedimentation characteristics of open and semi-closed hollow blocks are analyzed. The results show that the permeability of the hollow block plays a leading role in the internal flow velocity and turbulence intensity, and the semi-open hollow block with small permeability has a better effect in slowing down and turbulence control. The suspended sediment concentration near the bottom of open and semi-closed hollow blocks increases by 56% and 75%, respectively. Both of them can promote the deposition of sediment in the block. The environment of low flow velocity, sediment micro-deposition and water and sediment connected inside and outside by hollow blocks is the habitat requirement of macrobenthos, the structure of low turbulent flow inside the semi-enclosed hollow block is more favorable for the habitat and reproduction of macrobenthos.
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Key words:
- hollow block /
- flume experiment /
- Flow-3D /
- flow and sediment dynamic /
- deposition
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图 1 空心块体三视图及模型图（单位: mm）
Fig. 1 Three views and model diagram of the hollow block (unit: mm)
图 3 空心块体水槽试验测点布置（单位：mm）
Fig. 3 Layout of measuring points for hollow block flume experiment (unit: mm)
图 5 部分点位垂线方向流速（
${u} $ ）验证Fig. 5 Verification of vertical flow velocity (
${u} $ ) at some points
图 6 空心块体部分点位流速、紊动强度垂线分布
Fig. 6 Vertical distribution of velocity and turbulence intensity at some points in the hollow block
图 7 空心块体部分点位悬沙浓度垂线分布
Fig. 7 Vertical distribution of suspended sediment concentration at some points of the hollow block
图 9 半封闭型空心块体内部泥沙淤积分布
Fig. 9 Distribution of sediment deposition in semi-closed hollow block
图 10 空心块体近底层水流流速、紊动强度分布（截面z=5 cm）
Fig. 10 The distribution diagram of velocity and turbulence intensity near the bottom of the hollow block (Section z=5 cm)
图 11 空心块体侧视面流场分布（截面y=0 cm）
Fig. 11 The flow field distribution diagram of the hollow block in side view (Section y=0 cm)
图 12 空心块体近底层紊动能分布（截面z=5 cm）
Fig. 12 Distribution diagram of turbulent kinetic energy near the bottom of the hollow block (Section z=5 cm)
表 1 空心块体透水能力参数
Tab. 1 Hollow block water permeability parameter
结构型式 透水截面面积/cm2 总透水面积S0/cm2 开孔率S0/S x轴方向 y轴方向 z轴方向 开敞型 100 100 196 792 33% 半封闭型 19.6 19.2 顶面64
底面196337.6 14% 注：S为包含结构体外轮廓总面积S=20$ \text{×} $20$ \text{×} $6=2 400 （cm²）。 
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表 2 长江口目标生物生境需求指标[20]
Tab. 2 Target biological habitat demand indicators for the Changjiang River Estuary[20]
生物类别 代表性物种 生境需求指标 双壳类 河蚬、黑龙江河篮蛤、
彩虹明樱蛤等河蚬、黑龙江河篮蛤一般栖息在底质0～5 cm深度；彩虹明樱蛤栖息深度一般在4～15 cm 甲壳类 中华绒螯蟹等 中华绒螯蟹在南槽水域主要为抱卵蟹和蚤状幼体，抱卵蟹适应流速不大于1.5 m/s，
蚤状幼体适应流速不大于0.7 m/s，幼蟹介于两者之间多毛类 沙蚕 沙蚕栖息深度在0～30 cm，基本生活在沉积底质内，
受水流作用影响相对较小
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