DEVELOPMENT OF NEW METHOD BY IMP ACT ELAS TIC WAVE FOR INS - - PowerPoint PPT Presentation

▶

Jul 12, 2023 557 likes •680 views

Third National Dam Safety Conference 18-19 February 2017, Roorkee, India DEVELOPMENT OF NEW METHOD BY IMP ACT ELAS TIC WAVE FOR INS PECTION OF CONCRETE DAM BODY Shigeki Ichikawa, JWA Toshiro Kamada, Osaka Univ. Tomonobu Sugiura, JWA

SLIDE 1

DEVELOPMENT OF NEW METHOD BY IMP ACT ELAS TIC WAVE FOR INS PECTION OF CONCRETE DAM BODY

Shigeki Ichikawa, JWA Toshiro Kamada, Osaka Univ. Tomonobu Sugiura, JWA Naoyoshi Hayashi, JWA Kentaro Kido, JWA

Third National Dam Safety Conference 18-19 February 2017, Roorkee, India

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency

Japan Water Agency (JWA)

SLIDE 2

Introduction

Degradation of the horizontal construction joint faces of a dam body

Negative affects the stability of the body
Deterioration of a concrete dam that arises due to aging

Boring survey

High cost
Damage inflicted to the dam body
Single point inspection
Insufficient for investigating the total extent of degradation

2 Nondestructive inspection technique for surveying a dam body by using reflection of impact elastic waves

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency

SLIDE 3

S urvey Target Dam

Survey target dam;

JWA‘s concrete gravity dam
height of 42 m, crest length of 138 m
completed in 1975 (41 years ago)

3

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency

Jan. 1977

(Possible leakage path in dam body)

Mar. 2008

Waterstop Horizontal Construction Joint Transverse Joint Reservoir Crack

SLIDE 4

The Impact Elastic Wave Method (IEWM)

4

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency

Impact is applied to each point on the dam crest

SLIDE 5

Categorizing the Measured Waveforms

5

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency

Pattern A

Construction Joint

Single Impact

Bottom

Passing through No reflection was

bserved at the

evaluation depth Longitudinal wave (Compressional wave) Reflection definitely

bserved at a depth

deeper than the evaluation depth No cracks (separation)

M easured Waveform

SLIDE 6

Categorizing the Measured Waveforms

6

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency

Pattern B M ixture of passing through and reflection Reflection definitely

bserved at a depth

deeper than the evaluation depth Reflection observed at the evaluation depth but elastic wave passing through (propagating) deeper than the evaluation depth Partial cracks (separation)

Construction Joint Bottom M easured Waveform

SLIDE 7

Categorizing the Measured Waveforms

7

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency

Pattern C Only reflection and no passing through Continuous cracks (separation) Reflection observed at the evaluation depth and no reflection found deeper than the evaluation depth No waveform

M easured Waveform Construction Joint Bottom

SLIDE 8

Associating Measurement Results with the S tate of the Construction Joint Face

8

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency

Category Assumed State of the Joint Face around a M easuring Point Type I

 No separation or separation has been

completely sealed with filling etc., leaving no gaps.

 The waveform is classified into Pattern A.

Type II

 The major parts are the same as Type I, but

partly separated, which generates gaps.

 The waveform is classified into Pattern B.

Type III

 Parts are the same as Type I, but the rest is

separated, which generates gaps.

 The waveform is classified into Pattern B.

Type IV

 M ajor parts are separated, which generates

continuous gaps.

 The waveform is classified into Pattern C.

SLIDE 9

Relevancy Indices for Estimation of the S tate

f Construction Joint

9

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency

Category Rate of Waveform Patterns Type I 80% < A and C = 0% Type II

0 < A ≤ 80% and C = 0%, or 0 < C ≤ 20%

Type III

20 < C ≤ 80%, or 0 < A ≤ 20% and 80% ≤ C

Type IV

A = 0% and 80% ≤ C Ten or more waveforms were collected at each point, and the state

f each point was categorized based on the percentage of
ccurrence of each waveform pattern (A – C).

Based on the results of the IEWM of the 62 points for which the

actual state had been confirmed in the boring survey, relevancy indices for estimating the type of construction joint face (I - IV) from the rate of each pattern was determined.

SLIDE 10

Estimation of Horizontal Construction Joint Faces from Measurement Results

10

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency

Type I Type IV Type III Type II

 It is possible to estimate the state of each point on the grid

regarding the target faces using the rate of each waveform pattern

f the target construction joint face and the relevancy indices for

estimating the state of construction joint.

Sample Estimation of the State of a Horizontal Construction Joint Face

SLIDE 11

Conclusions

IEWM can reveal a range of degradation with regard to the

horizontal construction joint faces of a concrete dam body.

IEWM is expected to be an effective method for quantitative

evaluation of the state of horizontal joint and utilization to review the soundness of concrete dam body. For further improvement;

Laboratory tests of large specimens with artificial defects such as

inside cracks

Surveying from the inspection gallery inside the dam body
M easurements of other dam bodies

11 Thank you for your attention.

Incorporated Administrative Agency

Japan Water Agency

Incorporated Administrative Agency

Japan Water Agency