Sensitivity Analysis of Seepage Control Effect and Drainage Measures in the Water Conveyance System of Pumped Storage Power Stations

doi:10.11988/ckyyb.20231373

Abstract

Abstract:

The water conveyance and power generation system of pumped storage power stations is generally buried deeply,and the three-dimensional seepage field distribution of the plant’s chamber group is complex due to external seepage in the water diversion system. Drainage measures are crucial in controlling the seepage field of water transmission and power generation system. Using the three-dimensional seepage field finite element method, we constructed a numerical calculation model of Zhangye pumped storage power station’s water delivery and power generation system, integrating the water conveyance system, underground plant system, and seepage prevention and drainage systems. Based on the distribution law of seepage field within the power generation system, we analyzed the impact of the drainage system beneath the pressure pipeline and the plant’s drainage system on the seepage field. Results indicate that under normal operating conditions, most of the underground plant is above the wetting line, and seepage flow is maintained within a reasonable range under the designed seepage control plan. Seepage overflows occur near the bottom of the plant chamber group, the pipeline exhibits characteristics of internal water seepage, and the seepage flow of the tailwater system is relatively large. The lower drainage gallery of the pressure pipe significantly influences the seepage field of the pressure pipe and the upstream side of the plant. A smaller drainage hole spacing results in a lower wetting line and larger seepage flow in the corresponding area, with a drainage hole spacing of 3 m proving more reasonable. The drainage system in the plant area significantly affects the seepage field of the underground plant. As the drainage hole spacing increases, the drainage effect diminishes, the flow into the collection well decreases, the wetting line rises slightly, and a drainage hole spacing of 3 m is deemed more reasonable.

Key words: pumped storage power station, water transmission and power generation system, underground powerhouse, water conveyance system, drainage system, seepage analysis

CLC Number:

TV223.4水工建筑物的渗流和防渗

LI Feng, YANG Yu, WEN Li-feng, LI Yan-long. Sensitivity Analysis of Seepage Control Effect and Drainage Measures in the Water Conveyance System of Pumped Storage Power Stations[J]. Journal of Changjiang River Scientific Research Institute, 2024, 41(12): 109-116.

Figures/Tables 13

Fig.1 Plane layout of water transmission and power generation system

Fig.2 Three-dimensional finite element calculation model

Fig.3 Longitudinal profile of water transmission and power generation system

Fig.4 Comparison between borehole-measured average water level and calculated water level

Table 1 Inversion results of permeability coefficients fordifferent strata and faults

岩层	产状	渗透系数建议范围值/ (m·s^-1)	渗透系数取值/ (m·s^-1)
岩层	产状	渗透系数建议范围值/ (m·s^-1)	K_//	K_⊥
覆盖层	各向同性	3.85×10^-5~ 3.0×10^-4	6.0×10^-5	6.0×10^-5
强风化层	各向同性	≥8×10^-7	1.5×10^-5	1.5×10^-5
弱风化层	各向同性	6.5×10^-7~ 7.9×10^-6	2.3×10^-6	2.3×10^-6
微新岩层	各向同性	7×10^-9~ 4×10^-7	2.4×10^-7	2.4×10^-7
断裂层	NW320°~ 350°SW∠60°~75°	4.48×10^-7~ 1.24×10^-6	1.1×10^-6	6.0×10^-7

Fig.5 Contours of different cross-sectional positions

Table 2 Calculation conditions

计算工况	编号	工况条件
运行期	1	上库库水位为正常蓄水位,下库库水位为死水位,防渗排水系统正常工作,排水孔间隔为3 m
压力管道下层排水系统敏感性分析	2	厂房区防渗排水系统正常工作,压力管道下层排水孔间隔2 m
	3	厂房区防渗排水系统正常工作,压力管道下层排水孔间隔5 m
	4	厂房区防渗排水系统正常工作,压力管道下层排水孔完全失效
厂房区排水系统敏感性分析	5	下层排水廊道排水系统正常工作,厂房区排水孔间隔为2 m
	6	下层排水廊道排水系统正常工作,厂房区排水孔间隔为5 m
	7	下层排水廊道排水系统正常工作,厂房区排水孔间隔为7m

Fig.6 Infiltration line and water head distribution in the powerplant area during operation

Fig.7 Infiltration flow quantity of various parts during operation

Fig.8 Influence of the spacing of lower drainage holes in the pressure pipeline on the infiltration line of longitudinal section of the plant area

Fig.9 Infiltration flow quantity in different parts of the plant area with varied spacing of lower drainage holes in the pressure pipeline

Fig.10 Vertical profile distribution of infiltration lines in the plant area with varied spacing of drainage holes

Fig.11 Infiltration flow quantity in different parts of the plant area with varied spacing of drainage holes

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