NB/T 11171-2023
Design specifications for masonry dams (English Version)

Standard No.

NB/T 11171-2023

Language

Chinese, Available in English version

Release Date

2023

Published By

Professional Standard - Energy

Latest

NB/T 11171-2023

Introduction

Standard Framework and Technological Evolution

Technical Dimension	1990 Edition of the Standard	2023 Edition of the Standard	Technological Evolution
Dam Height Classification	Unclear Classification	Low Dam (＜30m)/Medium Dam (30-70m)/High Dam (＞70m)	Introduction of Quantitative Classification System
Seismic Design	General Requirements	High Dams Above Grade VII Require Finite Element Analysis	Special Requirements for Enhanced Seismic Resistance
Material standards	Stone strength level 4	6 levels of classification (30-100MPa)	Refined material control

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Analysis of core design parameters

4.1 Requirements for dam construction materials

The specification proposes three-level classification requirements for stone:

• Rough stone: thickness ≥0.15m, unit weight ≥25kg
• Block stone: thickness ≥0.2m, aspect ratio ≤3
• Coarse stone: flatness error ≤3%

Strength standard of cementing material:

Case study: A 70m medium dam was built with M12.5 cement mortar to construct stone blocks. The measured value of the deformation modulus of the masonry reached 12GPa, which met the requirements of Appendix B of the specification.

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Key points of load combination innovation

5.1 Load system of gravity dam

The 2023 version of the specification optimizes the load combination logic:

1. Basic combination: 8 types of conventional loads
2. Special combination: Add drainage failure conditions
3. Earthquake conditions: clarify finite element analysis requirements

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Implementation suggestions

Precautions for high dam design

In response to Article 1.0.3 of the specification:

• Dam body temperature field simulation analysis should be carried out
• Waterstop system should be set at the joints of the anti-seepage panel
• It is recommended to use distributed optical fiber for temperature monitoring

Engineering practice: A hydropower station in the southwest adopted the thrust pier calculation method in Appendix E of the specification during the construction of a stone arch dam. After optimization, the amount of concrete was reduced by 18%.

NB/T 11171-2023 Referenced Document

• DL/T 5207 Technical specifications for anti-scouring and anti-cavitation concrete for hydraulic structures
• NB 35047 Code for seismic design of hydraulic structures of hydropower project
• NB/T 10857 Design specifications for reasonable service life and durability of hydropower projects
• NB/T 10870 Specifications for design of concrete arch dams
• NB/T 10966 Technical guidelines for emptying reservoirs
• NB/T 11011 Code for Design of Hydraulic Concrete Structures

NB/T 11171-2023 history

• 2023 NB/T 11171-2023 Design specifications for masonry dams

Standard and Specification