Flow:The Sliding Crack
2021年7月4日Download here: http://gg.gg/v8zau
The composites with 2.5, 5.0, 7.5 and 10.0 vol.% reinforcement were fabricated by spark plasma sintering (SPS). Dry wear tests of the composites were performed against a 10 mm-diameter high-carbon-chromium steel ball under 23 N normal load, at a sliding speed of 100 mm/s and a sliding distance of 500 m using a ball-on-disk configuration. Investigation on the assessment of energy dissipation during non-sliding contacts is followed by the theoretical work of Hanson et al. , who model an actual fretting fatigue experimental situation and estimate the energy dissipation under cyclic tangential loading.They estimate the energy dissipation by taking into account the hysteresis loop of tangential force versus tangential displacement.
*Flow:the Sliding Crack Lock
*Flow:the Sliding Crack Windows
*Flow:the Sliding Crack Glass
*Flow:the Sliding Crack Filler
THIS PROJECT HAS BEEN COMPLETED AND IS BEING ARCHIVED IN ITS FINAL CONFIGURATION
The Kelly Barnes Dam, located above the Toccoa Falls Bible College near Toccoa, Georgia, failed in the early morning hours of November 6, 1977. Thirty-nine people died in the resulting flood, which inundated part of the campus including a trailer park. These Web pages make available two historical reports on the flood and an album of photos of the disaster.Additional information or other mentions of the Toccoa flood:
*NOAA Photo Library:
*Brief description of the flood in Summary of Significant Floods in the United States, Puerto Rico, and the Virgin Islands, 1970 Through 1989: USGS Water Supply Paper 2502
*The book Dam Break in Georgia: Sadness and Joy at Toccoa Falls by K. Neill Foster with Eric Mills (1978, Horizon House Publishers, 159 p.) tells the stories of many of the flood victims.
by Federal Investigative Board
Robert L. Crisp, Jr., Chairman
William E. Fox
Robert C. Robison
Vernon B. Sauer
December 21, 1977 ABSTRACT
The Kelly Barnes Dam failed about 1:30 a.m., on November 6, 1977. The dam went through various stages of development. First as a rock crib dam and then with subsequent stages as an earth dam. The rock crib dam was completed about 1899 to back up water which would be used to power a small hydroelectric plant located near the foot of the Falls. About 1937, the Toccoa Falls Bible Institute was interested in developing a more dependable power source and decided to build an earth dam over the rock crib dam. This construction was performed with equipment provided by a local manufacturer. After World War II, the earth fill was raised to a point where an earth spillway on the left side of the valley could be utilized, and a low point on the rim on the right side away from the dam would serve as an secondary spillway in case high flows occurred.
The final height of the dam was approximately 42 feet above the rock foundation. This installation served as a power source until 1957 for the Toccoa Falls Bible Institute, which later became the Toccoa Falls College. At this time, the development of power was stopped but the dam continued to be used as a recreation lake.
The Board could not determine a sole cause of the November 6, failure. It does conclude that a combination of factors caused the failure. The most probable causes are a local slide on the steep downstream slope probably associated with piping, an attendant localized breach in the crest followed by progressive erosion, saturation of the downstream embankment, and subsequently a total collapse of the structure. ACKNOWLEDGMENTS
The Board wishes to acknowledge its grateful appreciation to all the individuals, organizations, and groups that supplied information and assistance of any kind to this effort. This includes the following contributors:
*Office of the Governor of Georgia
*Toccoa Falls College and Staff
*Citizens of Toccoa Falls
*Citizens of Toccoa
*Citizens of Stephens County
*Stephens County Board of Commissioners - Mack Dalrymple, Chairman
*Georgia Baptist Assembly - Harold L. Sangster, Manager
*Toccca Falls College Students - past and present
*Sheraton Motor Inn, Toccoa, Georgia
*Governor’s Task Force on Dam Safety
*Georgia Department of Natural Resources
*Georgia Department of Transportation
*U.S. Army Corps of Engineers - South Atlantic Division, Savannah
*District, CERL, and Waterways Experiment Station
*U.S. Geological Survey
*National Weather Service - Southeast River Forecast Center, Weather Service
*Forecast Office (Atlanta)
*Soil Conservation Service
*Agricultural Stabilization and Conservation Service
*Federal Disaster Assistance Administration
*U.S. Army Forces Command Flight Detachment
*Professor George F. Sowers - Georgia Institute of Technology
*Dr. Timothy Long - Georgia Institute of Technology
*Dr. Pradeep Talwani - University of South Carolina
*Local, State and National Press AUTHORITY
On Sunday, November 6, 1977, at approximately 1:30 a.m., the Kelly Barnes Dam near Toccoa in Stephens County, Georgia, failed during a period of intensive rains. The resulting flood took 39 lives and did extensive damage to the Toccoa area and especially to the campus of the Toccoa Falls College.
Immediately following the disaster, the Honorable George Busbee, Governor of Georgia, asked the President of the United States for Federal technical assistance in assessing engineering, hydrologic, and other issues related to the failure of the Kelly Barnes Dam. On November 7, 1977, Governor Busbee appointed a ’Task Force on Dam Safety’ to, among other things, immediately initiate a responsible, coordinated inquiry into the circumstances surrounding this incident and causes thereof. He charged the Task Force with the preparation of an interim report to the Governor which will identify and inventory available Federal, State, local, and private investigatory resources and expertise and recommend the most appropriate and efficient means of examining the underlying causes of the disaster involving the Kelly Barnes Dam. On November 8, 1977, during a meeting with Governor Busbee, his newly appointed Task Force on Dam Safety, and others, it was publicly announced that President Carter had assured Governor Busbee that Federal assistance would be provided in connection with determining the cause of failure of the Kelly Barnes Dam. Thumbnail of White House memorandumDr. Phillip Smith of the President’s Office of Science and Technology Policy, representing the administration, announced that the Corps of Engineers had been assigned the mission of organizing and leading a Federal technical investigation. Subsequently, a memorandum from the White House to Secretary of the Army Clifford L. Alexander, Jr., (Exhibit 1) requested the Secretary: ’To authorize the Corps to provide necessary assistance over the next month or six weeks that will make possible a technical assessment of the Kelly Barnes Dam failure. Please do not hesitate to seek the assistance of other Federal agencies having useful expertise in this problem.’
The Corps requested and received assurances of assistance from the U.S. Geological Survey (Department of the Interior), the Soil Conservation Service (Department of Agriculture), and the National Weather Service (Department of Commerce). Accordingly, a technical Federal Investigative Board was formed consisting of:
Mr. Robert L. Crisp, Jr., Chairman, U.S. Army Corps of Engineers Mr. William E. Fox, National Weather Service
Mr. Robert C. Robison, Soil Conservation Service
Mr. Vernon B. Sauer, U.S. Geological Survey PURPOSE
The purpose of this report is to present the results of a Federal investigation into the failure of the Kelly Barnes Dam aimed at determining the probable cause(s) of failure.SCOPE
At the request of Governor Busbee, the Board restricted its attention to determining the probable cause(s) of failure of the dam and the technical details relating to the failure. Therefore, no attempt was made to assess downstream damage or to determine liability for the failure. The Board recognized that it might be virtually impossible to determine the exact cause of failure because the failure removed a major portion of the dam and masonry structures. Also, the age of the dam, the lack of design, construction, and maintenance records, further handicapped the investigation. The Board elected to examine all possibilities and then to offer its judgement as to the most likely occurrence.
Field investigations and data gathering were accomplished by personnel from each of the agencies on the Federal Investigative Board and various State agencies. The investigations made were:
*Detailed measurements, sketches, and plane table surveys.
*Core drilling for soil samples.
*Debris logging and sampling.
*Review of old records, including newspapers.
*Personal interviews with individuals having knowledge of the dam or its history.
*Public meeting to solicit information about the dam and conditions or incidents that may be related to its failure.
*Meteorological studies.
*Hydrologic and hydraulic studies.
*Laboratory testing.
*Stability analyses.
*Studies of old maps and photographs.
*Excavation of remaining portions of the dam. DESCRIPTION OF KELLY BARNES DAM
The Board was able to piece together a general picture of the dam prior to failure. The Kelly Barnes Lake was located near Toccoa, Georgia (Exhibit 2).
Click on image to view a larger version.
The dam was approximately 400 feet long with a crest width of approximately 20 feet and about 38 feet high at its maximum section. The dam was concave upstream filling a narrow portion of the gorge formed by Toccoa Creek. The dam impounded a lake at normal pool elevation of approximately 40 acres.
The dam and surrounding areas were covered by a heavy growth of bushes and trees. On the left abutment (looking downstream) an earth spillway (main earth spillway) had been excavated to the left of the dam. This spillway apparently carried all normal flow of water around the dam. Two masonry intake structures had been constructed on the left central upstream face of the dam and were partially or totally obscurred from view by the brush and trees. On the right rim (looking downstream) a low area in the approach road acted as a secondary earth spillway. The slopes of the dam, approximately one vertical (1V) on one horizontal (1H) were steep compared to today’s standards. A slide on the downstream slope had occurred in this area and had not been repaired.PUBLIC INPUT
Immediately after the Federal Investigative Board was formed on November 8, 1977, efforts were undertaken to obtain maximum public involvement. On November 10, a news release announced formation of the Board and solicited old photographs and first-hand knowledge about the dam and its construction history.
On November 14, a second news release was issued by the Board setting up a two-day public meeting at the Georgia Baptist Assembly on November 17-18 in an effort to encourage local people to provide any first-hand knowledge about the incidents leading up to the failure, copies of old photos, details about earlier construction features of the dam, observations on visits to the dam site, or any other knowledge which may provide a broad-based background. Copies of a public notice were sent by mail to every household and business firm in Toccoa and Toccoa Falls.
Attendance at the public meeting was sparse, except for news media, and limited information was produced by the public meeting.
Interviews were conducted by the Investigative Board following the public meeting with a number of local citizens who indicated various degrees of knowledge about the structure. Telephone interviews were conducted with people as far away as California and Texas in an effort to locate historical data about the dam. HISTORY
The history of the Kelly Barnes Dam as reconstructed, based on review of old records, maps, college albums, newspaper accounts, photographs, and interviews with historical witnesses, is as follows:
1. In 1899 a rock crib dam, constructed by Mr. E. P. Simpson, was completed at the present dam site. This dam furnished water to a small power plant known as the Toccoa Falls Light and Power Company (Photo 1). This plant is still located on what is now the Toccoa Falls College campus. Water for the power plant was delivered from the dam through a spiral riveted pipe (penstock) approximately 30-inches in diameter.
2. In the early 1930’s, Mr. Kelly Barnes, then the Business Manager for Toccoa Falls Institute (forerunner of the Toccoa Falls College), acquired the land for the school which included the E. P. Simpson Power Dam and another dam further upstream. An inspection of the upstream dam during the investigation revealed that it had been inoperative for a number of years and had no effect on the Kelly Barnes Dam. Records indicate it was destroyed by a runoff event in 1929. An earth fill dam was constructed at the site of the E. P. Simpson Dam in the period of 1939-1940. This earth dam incorporated all, or part of, the old crib dam into its downstream toe. Construction was accomplished using equipment reportedly furnished by the LeTourneau Company of Toccoa, manufacturer of self-powered earth scrapers. Conflicting information has been received, but the machinery apparently was operated by local persons, some of whom may have been students trained at the school. Prior to placing the earth fill, attempts may have been made to remove sediments that had accumulated behind the old crib dam. However, comments by historical witnesses, and evidence visible at the site after the recent failure, indicate that this removal was not extensive or complete. The fill was reportedly placed in layers and rolled by the movement of rubber-tired scrapers and a track-mounted dozer. According to witnesses, a low-level spillway outlet, consisting of a 30-inch metal pipe, was placed through the dam along the streambed with its inlet located on the upstream slope. The exact location, elevation, and configuration of this low-level spillway has not been established. There is also some question as to whether or not the spiral riveted penstock in the vicinity of the dam was replaced during this period. This dam became known as the Kelly Barnes Dam.
3. The March, 1946 issue of the Toccoa Falls News, the school newspaper, carries the story of a dam bursting approximately one mile above the school. This dam, said to be the McNeely Dam by a historical witness, was located on Dead Man’s Branch and would not have affected the Kelly Barnes Dam.
4. The June, 1948 issue of the Toccoa Falls News contains a reference to a new dam being constructed about one-half mile above the Falls. This is the location of the Kelly Barnes Dam. It may not have been a new dam but an addition or repair to the existing dam (Photo 2). Photographs were taken by a construction worker who welded the outlet pipes and who was also a student at Toccoa Falls College. These photographs, developed in 1949 (Photo 3) show the crest of the dam as construction progressed with separate inlets for a low-level spillway and a welded steel penstock to the power plant. The low-level spillway had a rectangular shaped masonry inlet which could be shut off with stop logs or flashboards. The inlet for the welded steel penstock was also masonry and controlled with a slide gate at the upstream toe of the dam. The approximate location of these inlets are shown on Figure 1.
Some historical witnesses remember the penstock slide gate but do not recall the masonry structure. After the failure, this gate was retrieved from below the dam site and found to be closed. The conduits for the spillway outlet and new penstock were both welded plate pipes approximately 30-inches in diameter. A historical witness stated that during placement of fill over the spillway conduit, the pipe began to cave in and had to be reinforced with metal struts. Descriptions of the earth fill construction and equipment are similar to the construction which occurred in the 1930’s (Photo 2). At this time or during previous construction, the old spiral riveted penstock pipe had been abandoned but not removed. Conflicting information suggests the possibility of a series of construction events during the 1940’s. A 1954 Survey of Buildings, Roads, Streams, and Lakes of the Toccoa Falls Institute (Figure 2) locates the overflow pipe (low-level spillway), a 24-inch conduit (welded steel penstock), and the intake structures.
5. Information available indicates that the fill was constructed to its final height in the late forties. However, a study of stereo-pairs of aerial photographs taken on January 17, 1955 shows the reservoir to be essentially empty at that time. The inlet structures, two earth spillways, and the pipe leading to the powerhouse are clearly visible. In later years a heavy growth of vegetation became established on both the upstream and downstream face and apparently obliterated the masonry intakes from view. Again, information received from historical witnesses conflicts as to whether or not two structures existed at the time of failure. Judging from the debris found downstream and the remains of the welded steel penstock, it is the Board’s opinion that both existed at the time of failure.
6. A number of observers informed the Board of seeing almost continual seepage on the downstream slope of the dam near the point of exit of the spillway pipe. Photographs obtained from one source taken in 1973 show that a large embankment slide had occurred on the downstream face of the dam (Photos 12 and 13). This 12-foot high, 30-foot wide slide of unknown depth, was observed on the lower one-third of the downstream slope in the area of the current failure section, which was the highest point of the dam. The slide left a two-foot, vertical, scarp face and partially exposed the end of a pipe. The slide, at the time of the photograph, was apparently not recent because of the existance of established vegetation on the slide area. The picture shows the pipe to be essentially clogged with silt and trash, but a very slight seepage was observed coming from the pipe. The area near the pipe contained water that was discolored by iron oxide, sulfur, or some oth er matter indicating little or no flow. The area adjacent to the recent dam failure was wet and spongy a week after the failure and seepage water was still coming from the toe near the right abutment (looking downstream) at that time.
7. In May, 1976, Toccoa Creek flooded below the Falls. Many other small rivers in the region also flooded, doing considerable damage to roads, bridges, and farm lands. The area was declared eligible for Federal Disaster Relief. Federal agencies examined the area and authorized $30,000 for repairs to roads of Toccoa Falls College. There was no reported inspection of the dam at that time. It is likely that the flooding was from local inflow of tributaries below Toccoa Falls as well as from the Toccoa Creek above the dam. SITE INSPECTIONS AND INVESTIGATIONS
1. General. Site investigations
https://diarynote.indered.space
The composites with 2.5, 5.0, 7.5 and 10.0 vol.% reinforcement were fabricated by spark plasma sintering (SPS). Dry wear tests of the composites were performed against a 10 mm-diameter high-carbon-chromium steel ball under 23 N normal load, at a sliding speed of 100 mm/s and a sliding distance of 500 m using a ball-on-disk configuration. Investigation on the assessment of energy dissipation during non-sliding contacts is followed by the theoretical work of Hanson et al. , who model an actual fretting fatigue experimental situation and estimate the energy dissipation under cyclic tangential loading.They estimate the energy dissipation by taking into account the hysteresis loop of tangential force versus tangential displacement.
*Flow:the Sliding Crack Lock
*Flow:the Sliding Crack Windows
*Flow:the Sliding Crack Glass
*Flow:the Sliding Crack Filler
THIS PROJECT HAS BEEN COMPLETED AND IS BEING ARCHIVED IN ITS FINAL CONFIGURATION
The Kelly Barnes Dam, located above the Toccoa Falls Bible College near Toccoa, Georgia, failed in the early morning hours of November 6, 1977. Thirty-nine people died in the resulting flood, which inundated part of the campus including a trailer park. These Web pages make available two historical reports on the flood and an album of photos of the disaster.Additional information or other mentions of the Toccoa flood:
*NOAA Photo Library:
*Brief description of the flood in Summary of Significant Floods in the United States, Puerto Rico, and the Virgin Islands, 1970 Through 1989: USGS Water Supply Paper 2502
*The book Dam Break in Georgia: Sadness and Joy at Toccoa Falls by K. Neill Foster with Eric Mills (1978, Horizon House Publishers, 159 p.) tells the stories of many of the flood victims.
by Federal Investigative Board
Robert L. Crisp, Jr., Chairman
William E. Fox
Robert C. Robison
Vernon B. Sauer
December 21, 1977 ABSTRACT
The Kelly Barnes Dam failed about 1:30 a.m., on November 6, 1977. The dam went through various stages of development. First as a rock crib dam and then with subsequent stages as an earth dam. The rock crib dam was completed about 1899 to back up water which would be used to power a small hydroelectric plant located near the foot of the Falls. About 1937, the Toccoa Falls Bible Institute was interested in developing a more dependable power source and decided to build an earth dam over the rock crib dam. This construction was performed with equipment provided by a local manufacturer. After World War II, the earth fill was raised to a point where an earth spillway on the left side of the valley could be utilized, and a low point on the rim on the right side away from the dam would serve as an secondary spillway in case high flows occurred.
The final height of the dam was approximately 42 feet above the rock foundation. This installation served as a power source until 1957 for the Toccoa Falls Bible Institute, which later became the Toccoa Falls College. At this time, the development of power was stopped but the dam continued to be used as a recreation lake.
The Board could not determine a sole cause of the November 6, failure. It does conclude that a combination of factors caused the failure. The most probable causes are a local slide on the steep downstream slope probably associated with piping, an attendant localized breach in the crest followed by progressive erosion, saturation of the downstream embankment, and subsequently a total collapse of the structure. ACKNOWLEDGMENTS
The Board wishes to acknowledge its grateful appreciation to all the individuals, organizations, and groups that supplied information and assistance of any kind to this effort. This includes the following contributors:
*Office of the Governor of Georgia
*Toccoa Falls College and Staff
*Citizens of Toccoa Falls
*Citizens of Toccoa
*Citizens of Stephens County
*Stephens County Board of Commissioners - Mack Dalrymple, Chairman
*Georgia Baptist Assembly - Harold L. Sangster, Manager
*Toccca Falls College Students - past and present
*Sheraton Motor Inn, Toccoa, Georgia
*Governor’s Task Force on Dam Safety
*Georgia Department of Natural Resources
*Georgia Department of Transportation
*U.S. Army Corps of Engineers - South Atlantic Division, Savannah
*District, CERL, and Waterways Experiment Station
*U.S. Geological Survey
*National Weather Service - Southeast River Forecast Center, Weather Service
*Forecast Office (Atlanta)
*Soil Conservation Service
*Agricultural Stabilization and Conservation Service
*Federal Disaster Assistance Administration
*U.S. Army Forces Command Flight Detachment
*Professor George F. Sowers - Georgia Institute of Technology
*Dr. Timothy Long - Georgia Institute of Technology
*Dr. Pradeep Talwani - University of South Carolina
*Local, State and National Press AUTHORITY
On Sunday, November 6, 1977, at approximately 1:30 a.m., the Kelly Barnes Dam near Toccoa in Stephens County, Georgia, failed during a period of intensive rains. The resulting flood took 39 lives and did extensive damage to the Toccoa area and especially to the campus of the Toccoa Falls College.
Immediately following the disaster, the Honorable George Busbee, Governor of Georgia, asked the President of the United States for Federal technical assistance in assessing engineering, hydrologic, and other issues related to the failure of the Kelly Barnes Dam. On November 7, 1977, Governor Busbee appointed a ’Task Force on Dam Safety’ to, among other things, immediately initiate a responsible, coordinated inquiry into the circumstances surrounding this incident and causes thereof. He charged the Task Force with the preparation of an interim report to the Governor which will identify and inventory available Federal, State, local, and private investigatory resources and expertise and recommend the most appropriate and efficient means of examining the underlying causes of the disaster involving the Kelly Barnes Dam. On November 8, 1977, during a meeting with Governor Busbee, his newly appointed Task Force on Dam Safety, and others, it was publicly announced that President Carter had assured Governor Busbee that Federal assistance would be provided in connection with determining the cause of failure of the Kelly Barnes Dam. Thumbnail of White House memorandumDr. Phillip Smith of the President’s Office of Science and Technology Policy, representing the administration, announced that the Corps of Engineers had been assigned the mission of organizing and leading a Federal technical investigation. Subsequently, a memorandum from the White House to Secretary of the Army Clifford L. Alexander, Jr., (Exhibit 1) requested the Secretary: ’To authorize the Corps to provide necessary assistance over the next month or six weeks that will make possible a technical assessment of the Kelly Barnes Dam failure. Please do not hesitate to seek the assistance of other Federal agencies having useful expertise in this problem.’
The Corps requested and received assurances of assistance from the U.S. Geological Survey (Department of the Interior), the Soil Conservation Service (Department of Agriculture), and the National Weather Service (Department of Commerce). Accordingly, a technical Federal Investigative Board was formed consisting of:
Mr. Robert L. Crisp, Jr., Chairman, U.S. Army Corps of Engineers Mr. William E. Fox, National Weather Service
Mr. Robert C. Robison, Soil Conservation Service
Mr. Vernon B. Sauer, U.S. Geological Survey PURPOSE
The purpose of this report is to present the results of a Federal investigation into the failure of the Kelly Barnes Dam aimed at determining the probable cause(s) of failure.SCOPE
At the request of Governor Busbee, the Board restricted its attention to determining the probable cause(s) of failure of the dam and the technical details relating to the failure. Therefore, no attempt was made to assess downstream damage or to determine liability for the failure. The Board recognized that it might be virtually impossible to determine the exact cause of failure because the failure removed a major portion of the dam and masonry structures. Also, the age of the dam, the lack of design, construction, and maintenance records, further handicapped the investigation. The Board elected to examine all possibilities and then to offer its judgement as to the most likely occurrence.
Field investigations and data gathering were accomplished by personnel from each of the agencies on the Federal Investigative Board and various State agencies. The investigations made were:
*Detailed measurements, sketches, and plane table surveys.
*Core drilling for soil samples.
*Debris logging and sampling.
*Review of old records, including newspapers.
*Personal interviews with individuals having knowledge of the dam or its history.
*Public meeting to solicit information about the dam and conditions or incidents that may be related to its failure.
*Meteorological studies.
*Hydrologic and hydraulic studies.
*Laboratory testing.
*Stability analyses.
*Studies of old maps and photographs.
*Excavation of remaining portions of the dam. DESCRIPTION OF KELLY BARNES DAM
The Board was able to piece together a general picture of the dam prior to failure. The Kelly Barnes Lake was located near Toccoa, Georgia (Exhibit 2).
Click on image to view a larger version.
The dam was approximately 400 feet long with a crest width of approximately 20 feet and about 38 feet high at its maximum section. The dam was concave upstream filling a narrow portion of the gorge formed by Toccoa Creek. The dam impounded a lake at normal pool elevation of approximately 40 acres.
The dam and surrounding areas were covered by a heavy growth of bushes and trees. On the left abutment (looking downstream) an earth spillway (main earth spillway) had been excavated to the left of the dam. This spillway apparently carried all normal flow of water around the dam. Two masonry intake structures had been constructed on the left central upstream face of the dam and were partially or totally obscurred from view by the brush and trees. On the right rim (looking downstream) a low area in the approach road acted as a secondary earth spillway. The slopes of the dam, approximately one vertical (1V) on one horizontal (1H) were steep compared to today’s standards. A slide on the downstream slope had occurred in this area and had not been repaired.PUBLIC INPUT
Immediately after the Federal Investigative Board was formed on November 8, 1977, efforts were undertaken to obtain maximum public involvement. On November 10, a news release announced formation of the Board and solicited old photographs and first-hand knowledge about the dam and its construction history.
On November 14, a second news release was issued by the Board setting up a two-day public meeting at the Georgia Baptist Assembly on November 17-18 in an effort to encourage local people to provide any first-hand knowledge about the incidents leading up to the failure, copies of old photos, details about earlier construction features of the dam, observations on visits to the dam site, or any other knowledge which may provide a broad-based background. Copies of a public notice were sent by mail to every household and business firm in Toccoa and Toccoa Falls.
Attendance at the public meeting was sparse, except for news media, and limited information was produced by the public meeting.
Interviews were conducted by the Investigative Board following the public meeting with a number of local citizens who indicated various degrees of knowledge about the structure. Telephone interviews were conducted with people as far away as California and Texas in an effort to locate historical data about the dam. HISTORY
The history of the Kelly Barnes Dam as reconstructed, based on review of old records, maps, college albums, newspaper accounts, photographs, and interviews with historical witnesses, is as follows:
1. In 1899 a rock crib dam, constructed by Mr. E. P. Simpson, was completed at the present dam site. This dam furnished water to a small power plant known as the Toccoa Falls Light and Power Company (Photo 1). This plant is still located on what is now the Toccoa Falls College campus. Water for the power plant was delivered from the dam through a spiral riveted pipe (penstock) approximately 30-inches in diameter.
2. In the early 1930’s, Mr. Kelly Barnes, then the Business Manager for Toccoa Falls Institute (forerunner of the Toccoa Falls College), acquired the land for the school which included the E. P. Simpson Power Dam and another dam further upstream. An inspection of the upstream dam during the investigation revealed that it had been inoperative for a number of years and had no effect on the Kelly Barnes Dam. Records indicate it was destroyed by a runoff event in 1929. An earth fill dam was constructed at the site of the E. P. Simpson Dam in the period of 1939-1940. This earth dam incorporated all, or part of, the old crib dam into its downstream toe. Construction was accomplished using equipment reportedly furnished by the LeTourneau Company of Toccoa, manufacturer of self-powered earth scrapers. Conflicting information has been received, but the machinery apparently was operated by local persons, some of whom may have been students trained at the school. Prior to placing the earth fill, attempts may have been made to remove sediments that had accumulated behind the old crib dam. However, comments by historical witnesses, and evidence visible at the site after the recent failure, indicate that this removal was not extensive or complete. The fill was reportedly placed in layers and rolled by the movement of rubber-tired scrapers and a track-mounted dozer. According to witnesses, a low-level spillway outlet, consisting of a 30-inch metal pipe, was placed through the dam along the streambed with its inlet located on the upstream slope. The exact location, elevation, and configuration of this low-level spillway has not been established. There is also some question as to whether or not the spiral riveted penstock in the vicinity of the dam was replaced during this period. This dam became known as the Kelly Barnes Dam.
3. The March, 1946 issue of the Toccoa Falls News, the school newspaper, carries the story of a dam bursting approximately one mile above the school. This dam, said to be the McNeely Dam by a historical witness, was located on Dead Man’s Branch and would not have affected the Kelly Barnes Dam.
4. The June, 1948 issue of the Toccoa Falls News contains a reference to a new dam being constructed about one-half mile above the Falls. This is the location of the Kelly Barnes Dam. It may not have been a new dam but an addition or repair to the existing dam (Photo 2). Photographs were taken by a construction worker who welded the outlet pipes and who was also a student at Toccoa Falls College. These photographs, developed in 1949 (Photo 3) show the crest of the dam as construction progressed with separate inlets for a low-level spillway and a welded steel penstock to the power plant. The low-level spillway had a rectangular shaped masonry inlet which could be shut off with stop logs or flashboards. The inlet for the welded steel penstock was also masonry and controlled with a slide gate at the upstream toe of the dam. The approximate location of these inlets are shown on Figure 1.
Some historical witnesses remember the penstock slide gate but do not recall the masonry structure. After the failure, this gate was retrieved from below the dam site and found to be closed. The conduits for the spillway outlet and new penstock were both welded plate pipes approximately 30-inches in diameter. A historical witness stated that during placement of fill over the spillway conduit, the pipe began to cave in and had to be reinforced with metal struts. Descriptions of the earth fill construction and equipment are similar to the construction which occurred in the 1930’s (Photo 2). At this time or during previous construction, the old spiral riveted penstock pipe had been abandoned but not removed. Conflicting information suggests the possibility of a series of construction events during the 1940’s. A 1954 Survey of Buildings, Roads, Streams, and Lakes of the Toccoa Falls Institute (Figure 2) locates the overflow pipe (low-level spillway), a 24-inch conduit (welded steel penstock), and the intake structures.
5. Information available indicates that the fill was constructed to its final height in the late forties. However, a study of stereo-pairs of aerial photographs taken on January 17, 1955 shows the reservoir to be essentially empty at that time. The inlet structures, two earth spillways, and the pipe leading to the powerhouse are clearly visible. In later years a heavy growth of vegetation became established on both the upstream and downstream face and apparently obliterated the masonry intakes from view. Again, information received from historical witnesses conflicts as to whether or not two structures existed at the time of failure. Judging from the debris found downstream and the remains of the welded steel penstock, it is the Board’s opinion that both existed at the time of failure.
6. A number of observers informed the Board of seeing almost continual seepage on the downstream slope of the dam near the point of exit of the spillway pipe. Photographs obtained from one source taken in 1973 show that a large embankment slide had occurred on the downstream face of the dam (Photos 12 and 13). This 12-foot high, 30-foot wide slide of unknown depth, was observed on the lower one-third of the downstream slope in the area of the current failure section, which was the highest point of the dam. The slide left a two-foot, vertical, scarp face and partially exposed the end of a pipe. The slide, at the time of the photograph, was apparently not recent because of the existance of established vegetation on the slide area. The picture shows the pipe to be essentially clogged with silt and trash, but a very slight seepage was observed coming from the pipe. The area near the pipe contained water that was discolored by iron oxide, sulfur, or some oth er matter indicating little or no flow. The area adjacent to the recent dam failure was wet and spongy a week after the failure and seepage water was still coming from the toe near the right abutment (looking downstream) at that time.
7. In May, 1976, Toccoa Creek flooded below the Falls. Many other small rivers in the region also flooded, doing considerable damage to roads, bridges, and farm lands. The area was declared eligible for Federal Disaster Relief. Federal agencies examined the area and authorized $30,000 for repairs to roads of Toccoa Falls College. There was no reported inspection of the dam at that time. It is likely that the flooding was from local inflow of tributaries below Toccoa Falls as well as from the Toccoa Creek above the dam. SITE INSPECTIONS AND INVESTIGATIONS
1. General. Site investigations
https://diarynote.indered.space
コメント