On a Saturday morning of late June, 2009, a 13-story apartment building collapsed. Lotus Riverside Block 7 lay next to a river, and the foundation structure consisted of Precast Concrete Piles. When excavating sub-grade parking garage, construction workers dumped the removed soil adjacent to Block 7, on the side of the building opposite the river. During a heavy rain, the soil became dense and fluid with water. This caused a sideward pressure on the piles and soil below the structure. The piles snapped and the building toppled over. Unfortunately, the collapse killed one worker and affected nearby citizens. After investigation, it was concluded that the collapse was caused by the excess soil storage during construction.
Figure 1: The Lotus Riverside Block 7 apartment building collapsed on the morning of June 27, 2009, killing one worker (Photo can be found at the following URL: http://www.bloomberg.com/bw/articles/2012-09-27/the-cracks-in-chinas-shiny-buildings)
Construction Concerns in China
China tends to be known for its inconsistency in construction standards. Many Chinese infrastructure and building projects, when driven by schedule, are not build as designed. When economic progress is in mind, projects are often built ahead of schedule and quality an even tradeoff with time. Politicians push schedule to increase their image appeal.
A lack in construction leadership qualifications leads to sloppy workmanship. Contractors prefer to use cheap building materials in place of durable and sustainable products. When approaching the urban areas, enforcement and quality control becomes more stringent. However, poor construction habits continue to endanger rural and suburban life.
(Bristow 2007)
Illegal Practice
Nine people connected to the collapse had been apprehended. Board members of the developer, Shanghai Meidu Real Estate Development, were also employed by the local government- a practice illegitimate according to law. In addition, the developer’s construction license had expired five years prior.
(Li 2009)
Events Leading Up to the Collapse
Lotus Riverside Block 7 was part of an 11 block project in the Minhang District of Shanghai, China. The building had almost been finished and the construction of supporting parking spaces began. The project design included a below grade parking garage adjacent to the structure. Workers piled soil on the opposite side of the structure.
Heavy rain fell on days prior to the collapse. One day before the collapse, a large section of the contiguous river’s floodwall had been compromised. The site contained substantial amounts of wet soil located in an inconvenient manor.
(Fact behind Building Collapse in Shanghai)
Causes of the Failure
The Collapse
On June 27, 2009, 5:30am, the newly built and apartment building collapsed in Shanghai, China. The 13 story structure was part
of a larger building complex, with continuous construction taking place. While storing soil on the North side of the building, the contractor excavated for the subterranean garage on the South side of the building. The garage was 15 feet deep while the soil stacked to 33 feet high.
The heavy rainfall that occurred on days leading up to the collapse, added to observation from images taken after the collapse, proved that the site soil was saturated with water. The massive soil mound created a large soil pressure on the North side of the building. The garage excavation reduced the soil pressure on the South side of the building. This differentiation caused a net soil pressure flowing in the South direction, towards the unbuilt garage.
The apartment complex used prestressed precast concrete piles as a foundation system. A flow of soil reduced stability in the deep foundation. When the precast piles snapped and the building began to tilt. The building fell, sideways, directly onto the excavated garage.
(Li 2009)
Figure 2: Leading up to the collapse, workers piled a large mound of soil on the side of the building opposite the garage (Photo can be found at the following URL: http://www.vegvesen.no/_attachment/220503/binary/419425)
Figure 3: Heavy rain and excess soil adjacent to the structure caused the piles to snap (Photo can be found at the following URL: http://www.vegvesen.no/_attachment/220503/binary/419425)
Prestressed Precast Concrete Piles
Prestressed Precast Concrete Piles are a common alternative to steel piles. Benefits include durability, adaptability, and high load capacity. Concrete pile design offers a wide variety of shapes including the hollow cylindrical configuration used in Lotus Riverside Block 7. Hollow piles, in comparison to solid piles, have a reduction in bearing and flexural load capacity. Net directional soil pressure could cause shear and flexural loads on the piles not originally designed for.
Unlike columns, piles are continuously braced by soil. When the soil moved due to pressure differential, it was not stable enough to brace the pile. The lack of bracing on the pile increased the pile’s effective length, thus magnifying newly combined compressive and bending loads on the specimen. The combination of gravity loads, flexural loads, and a lack of bracing caused the piles to fail catastrophically.
(Dick 2005)
Figure 4: The foundation system used circular hollow precast prestressed concrete piles (Photo can be found at the following URL: http://www.vegvesen.no/_attachment/220503/binary/419425)
Figure 5: The concrete piles were overstressed due to combined loadings, not originally designed for, causing catastrophic failure (Photo can be found at the following URL: http://www.vegvesen.no/_attachment/220503/binary/419425)
Soil Properties
The weight of soil varies greatly with the amount of water it retains. Dry soil does not weigh nearly as much as wet soil. The retention of water also changes the mechanics of soil’s properties. As saturation in soil increase, it becomes more viscous and, consequently, acts more fluid-like. As the earth gets deeper, this fluidity causes higher lateral pressure on nearby soil. When the top surface is level, and all soil conditions are the identical, similar lateral pressures allow the soil to be in equilibrium, and there is no flow or movement. Variable heights in top surface break that equilibrium and can cause erosion. Thus there exists the need for retaining walls when designing multi-level landscapes.
A large mound of soil will cause the soil below to compress or push outwards. Rain, producing soil saturation and fluidity, increases these affects. The soil pushed towards the river, leading to the failure of its floodwall; and pushed towards the excavated garage, leading to a flow below the building.
Effects of the Failure
Damages
Unfortunately, the life of one worker was lost on the Saturday morning of the collapse. The collapse also caused significant monetary damage. 120 families initially had to move from their homes and stay in hotels that were paid for by the local government. Cost of materials, administration, and labor had been wasted due to destruction of the almost finished building. A new structure had to be rebuilt on Block 7. Many homebuyers claimed compensation for the damages to their investment. Prices of the apartments estimated approximately $209 per square foot.
(Li 2009)
Effect on the Community
Surrounding buildings had been evacuated immediately following the collapse. Nearby residents described the collapse as an earthquake, and had to stay in hotels paid for by the government. Those who bought homes in the fallen condominium and apart of the 11 block complex demanded for the return of their investment. Because of rising property values, home buyers also demanded for compensation for the difference in housing costs. Chinese law states property owners of collapsed structure shall be compensated, but owners of apartments in surrounding buildings are not required by law to receive compensation.
(Li 2009)
Concluding Statements
Prevention and Lessons Learned
With better practice of construction sequence and planning, the collapse of Lotus Riverside Block 7 could have been prevented. For most areas, large mounds of soil are not a danger, even in wet conditions. The soil became a danger in this case because the site lay immediately between a river and excavation. The heavy, saturated soil cause large lateral pressures possibly leading to a break in the river’s floodwall. It was not determined whether the break had added to the soil loads, but the lateral pressure in the wet soil caused by the mound initiated a movement of earth below the building, towards the excavation.
It had been determined by the investigation team, that the earth below the building could withstand a mound of saturated soil up to 16½ feet. Therefore, the collapse could have been avoided if the contractor did not stack the soil higher than the previously described load limit. If the soil laydown had been distributed evenly throughout the site, the mound could have remained below the 16½ foot requirement. If the contractor were running low on space, the soil could have been removed from the site entirely.
The collapse was an uncommon type of collapse, buildings do not often tip over. An expert on the investigation team, Gu Guorong, stated, “I have never seen or heard of such an accident in my whole 46 years in the industry.” Through research, it is not easy to find a failure similar to Lotus Riverside Block 7, following its collapse. The importance of construction sequencing and site planning can be learned from this collapse. All building components failed due to reasons other than design. Site planning should not only consider cost and schedule, but also safety. When considering safety, it of upmost importance to consider the secondary effects of each action. This involves the use of engineers, along with construction managers, to ensure safety during the execution of construction.
Closing
Lotus Riverside Block 7 had been designed properly. The precast prestressed concrete piles failed due to a differentiation in soil pressures caused by inadequate construction site planning and sequencing. A large soil mound, created from excavation compact, provided high lateral pressures in the saturated soil beneath. Due to a garage excavation, the soil on the opposite side of the building could not provide equilibrium in lateral pressure; thus causing the soil to flow from under the mound, through the foundation system, towards the garage.
Flow of the soil left the concrete piles unbraced. Combined loads from the building gravity system and lateral soil caused a compression and bending condition. This condition, paired with the lack of bracing, led to failure of the piles and ultimately the collapse of the building.
The collapse caused damages of monetary value and loss of life. The failure could have been avoided by distributing the project’s excess soil evenly throughout the site or removing the soil entirely. The fact that this catastrophic collapse could have been avoided very easily, leads to the importance of how construction planning should be engineered, rather than simply created.
Shanghai Meidu Real Estate Development had been conducting business illegally. Although there were no large shortcuts taken in design, material selection, and building construction, Shanghai Meidu’s construction license had expired. This has a direct correlation with the insufficient construction practices leading to the collapse. Fortunately, China’s construction practices have been improving and no collapses similar to the Lotus Riverside Block 7 have occurred since.
The ‘BBC’ news article was written before the collapse. It describes the corruption, shortage of skills, and shoddy workmanship that takes place in the construction industry of China.
China experiences many collapses due to quality control issues. This article relates the Block 7 collapse to building failures in similar conditions.
Dick, John (2005). Precast Concrete Piles Provide Durability, Versatility, Precast/Prestressed Concrete Institute, Chicago, IL
This pamphlet on precast prestressed concrete piles describes the uses and types of prestressed concrete piles. It explains the advantages, as well as limitations, of the foundation system.
This article is a comprehensive explanation of how the building failed. It contains descriptive diagrams, referring to how load transfer of soil caused the collapse. Pictures, providing evidence of a failed foundation system, are shown at the end of this article.
The ‘Bloomberg’ article describes the challenges China faces in its construction industry, that relate to the collapse. It also explains that the cause of the collapse is a common issue that leads to many deaths in China.
Li, Cao (June 29, 2009). “Anger and tears over collapse of building”, China Daily
This article was published two days after the collapse. It contains witness accounts of the building failure and references the initial investigative report.
Li, Cao (July 4, 2009). “Cost-cutting not cause of tower’s fall”, China Daily
This article introduces reasons as to why Block 7 failed. It references a news conference held by Shanghai authorities. This article is an update to “Anger and tears over collapse of building.”
Li, Cao (July 8, 2009). “Fatal collapse rings alarm bells for developers”, China Daily
In this article, Shanghai experts in construction and real estate are quoted. They explain how the Chinese construction industry and economy may have affected the quality and workmanship of the building during the construction process. It also contains a site plan of the building complex.
Shanghai, China - June 2009
Zachary Tauber, BAE/MAE, The Pennsylvania State University, 2016
Table of Contents
Key Words
Lotus, Riverside, Block 7, Prestressed, Precast, Piles, Soil, Construction, Site, Collapse
Introduction
On a Saturday morning of late June, 2009, a 13-story apartment building collapsed. Lotus Riverside Block 7 lay next to a river, and the foundation structure consisted of Precast Concrete Piles. When excavating sub-grade parking garage, construction workers dumped the removed soil adjacent to Block 7, on the side of the building opposite the river. During a heavy rain, the soil became dense and fluid with water. This caused a sideward pressure on the piles and soil below the structure. The piles snapped and the building toppled over. Unfortunately, the collapse killed one worker and affected nearby citizens. After investigation, it was concluded that the collapse was caused by the excess soil storage during construction.
Construction Concerns in China
China tends to be known for its inconsistency in construction standards. Many Chinese infrastructure and building projects, when driven by schedule, are not build as designed. When economic progress is in mind, projects are often built ahead of schedule and quality an even tradeoff with time. Politicians push schedule to increase their image appeal.
A lack in construction leadership qualifications leads to sloppy workmanship. Contractors prefer to use cheap building materials in place of durable and sustainable products. When approaching the urban areas, enforcement and quality control becomes more stringent. However, poor construction habits continue to endanger rural and suburban life.
(Bristow 2007)
Illegal Practice
Nine people connected to the collapse had been apprehended. Board members of the developer, Shanghai Meidu Real Estate Development, were also employed by the local government- a practice illegitimate according to law. In addition, the developer’s construction license had expired five years prior.
(Li 2009)
Events Leading Up to the Collapse
Lotus Riverside Block 7 was part of an 11 block project in the Minhang District of Shanghai, China. The building had almost been finished and the construction of supporting parking spaces began. The project design included a below grade parking garage adjacent to the structure. Workers piled soil on the opposite side of the structure.
Heavy rain fell on days prior to the collapse. One day before the collapse, a large section of the contiguous river’s floodwall had been compromised. The site contained substantial amounts of wet soil located in an inconvenient manor.
(Fact behind Building Collapse in Shanghai)
Causes of the Failure
The Collapse
On June 27, 2009, 5:30am, the newly built and apartment building collapsed in Shanghai, China. The 13 story structure was part
of a larger building complex, with continuous construction taking place. While storing soil on the North side of the building, the contractor excavated for the subterranean garage on the South side of the building. The garage was 15 feet deep while the soil stacked to 33 feet high.
The heavy rainfall that occurred on days leading up to the collapse, added to observation from images taken after the collapse, proved that the site soil was saturated with water. The massive soil mound created a large soil pressure on the North side of the building. The garage excavation reduced the soil pressure on the South side of the building. This differentiation caused a net soil pressure flowing in the South direction, towards the unbuilt garage.
The apartment complex used prestressed precast concrete piles as a foundation system. A flow of soil reduced stability in the deep foundation. When the precast piles snapped and the building began to tilt. The building fell, sideways, directly onto the excavated garage.
(Li 2009)
Prestressed Precast Concrete Piles
Prestressed Precast Concrete Piles are a common alternative to steel piles. Benefits include durability, adaptability, and high load capacity. Concrete pile design offers a wide variety of shapes including the hollow cylindrical configuration used in Lotus Riverside Block 7. Hollow piles, in comparison to solid piles, have a reduction in bearing and flexural load capacity. Net directional soil pressure could cause shear and flexural loads on the piles not originally designed for.
Unlike columns, piles are continuously braced by soil. When the soil moved due to pressure differential, it was not stable enough to brace the pile. The lack of bracing on the pile increased the pile’s effective length, thus magnifying newly combined compressive and bending loads on the specimen. The combination of gravity loads, flexural loads, and a lack of bracing caused the piles to fail catastrophically.
(Dick 2005)
Soil Properties
The weight of soil varies greatly with the amount of water it retains. Dry soil does not weigh nearly as much as wet soil. The retention of water also changes the mechanics of soil’s properties. As saturation in soil increase, it becomes more viscous and, consequently, acts more fluid-like. As the earth gets deeper, this fluidity causes higher lateral pressure on nearby soil. When the top surface is level, and all soil conditions are the identical, similar lateral pressures allow the soil to be in equilibrium, and there is no flow or movement. Variable heights in top surface break that equilibrium and can cause erosion. Thus there exists the need for retaining walls when designing multi-level landscapes.
A large mound of soil will cause the soil below to compress or push outwards. Rain, producing soil saturation and fluidity, increases these affects. The soil pushed towards the river, leading to the failure of its floodwall; and pushed towards the excavated garage, leading to a flow below the building.
Effects of the Failure
Damages
Unfortunately, the life of one worker was lost on the Saturday morning of the collapse. The collapse also caused significant monetary damage. 120 families initially had to move from their homes and stay in hotels that were paid for by the local government. Cost of materials, administration, and labor had been wasted due to destruction of the almost finished building. A new structure had to be rebuilt on Block 7. Many homebuyers claimed compensation for the damages to their investment. Prices of the apartments estimated approximately $209 per square foot.
(Li 2009)
Effect on the Community
Surrounding buildings had been evacuated immediately following the collapse. Nearby residents described the collapse as an earthquake, and had to stay in hotels paid for by the government. Those who bought homes in the fallen condominium and apart of the 11 block complex demanded for the return of their investment. Because of rising property values, home buyers also demanded for compensation for the difference in housing costs. Chinese law states property owners of collapsed structure shall be compensated, but owners of apartments in surrounding buildings are not required by law to receive compensation.
(Li 2009)
Concluding Statements
Prevention and Lessons Learned
With better practice of construction sequence and planning, the collapse of Lotus Riverside Block 7 could have been prevented. For most areas, large mounds of soil are not a danger, even in wet conditions. The soil became a danger in this case because the site lay immediately between a river and excavation. The heavy, saturated soil cause large lateral pressures possibly leading to a break in the river’s floodwall. It was not determined whether the break had added to the soil loads, but the lateral pressure in the wet soil caused by the mound initiated a movement of earth below the building, towards the excavation.
It had been determined by the investigation team, that the earth below the building could withstand a mound of saturated soil up to 16½ feet. Therefore, the collapse could have been avoided if the contractor did not stack the soil higher than the previously described load limit. If the soil laydown had been distributed evenly throughout the site, the mound could have remained below the 16½ foot requirement. If the contractor were running low on space, the soil could have been removed from the site entirely.
The collapse was an uncommon type of collapse, buildings do not often tip over. An expert on the investigation team, Gu Guorong, stated, “I have never seen or heard of such an accident in my whole 46 years in the industry.” Through research, it is not easy to find a failure similar to Lotus Riverside Block 7, following its collapse. The importance of construction sequencing and site planning can be learned from this collapse. All building components failed due to reasons other than design. Site planning should not only consider cost and schedule, but also safety. When considering safety, it of upmost importance to consider the secondary effects of each action. This involves the use of engineers, along with construction managers, to ensure safety during the execution of construction.
Closing
Lotus Riverside Block 7 had been designed properly. The precast prestressed concrete piles failed due to a differentiation in soil pressures caused by inadequate construction site planning and sequencing. A large soil mound, created from excavation compact, provided high lateral pressures in the saturated soil beneath. Due to a garage excavation, the soil on the opposite side of the building could not provide equilibrium in lateral pressure; thus causing the soil to flow from under the mound, through the foundation system, towards the garage.
Flow of the soil left the concrete piles unbraced. Combined loads from the building gravity system and lateral soil caused a compression and bending condition. This condition, paired with the lack of bracing, led to failure of the piles and ultimately the collapse of the building.
The collapse caused damages of monetary value and loss of life. The failure could have been avoided by distributing the project’s excess soil evenly throughout the site or removing the soil entirely. The fact that this catastrophic collapse could have been avoided very easily, leads to the importance of how construction planning should be engineered, rather than simply created.
Shanghai Meidu Real Estate Development had been conducting business illegally. Although there were no large shortcuts taken in design, material selection, and building construction, Shanghai Meidu’s construction license had expired. This has a direct correlation with the insufficient construction practices leading to the collapse. Fortunately, China’s construction practices have been improving and no collapses similar to the Lotus Riverside Block 7 have occurred since.
Bibliography
Bristow, Michael (August 14, 2007), “China’s construction projects ‘rushed’”, BBC News, Beijing, <http://news.bbc.co.uk/2/hi/asia-pacific/6945972.stm> (November 5, 2015)
Canaves, Sky (June 29, 2009). “Shanghai Building Collapse, Nearly Intact”, China Real Time, <**http://blogs.wsj.com/chinarealtime/2009/06/29/shanghai-building-collapses-nearly-intact/**> (October 6, 2015)
Dick, John (2005). Precast Concrete Piles Provide Durability, Versatility, Precast/Prestressed Concrete Institute, Chicago, IL
“Fact behind Building Collapse in Shanghai”, NPRA, <**http://www.vegvesen.no/_attachment/220503/binary/419425**> (Sept. 30, 2015)
Foster, Peter (June 29, 2009). “Nine held over Shanhai building collapse”, The Telegraph, <**http://www.telegraph.co.uk/news/worldnews/asia/china/5685963/Nine-held-over-Shanghai-building-collapse.html**> (October 6, 2015)
(July 3, 2009) “Cause of fatal collapse in Shanghai”, The Star Online, <**https://www.youtube.com/watch?v=TGHqXM5OGtY**> (October 6, 2015)
Larson, Christina (September 27, 2012), “The Cracks in China’s Shiny Buildings”, Bloomberg Business, <**http://www.bloomberg.com/bw/articles/2012-09-27/the-cracks-in-chinas-shiny-buildings**> (October 6, 2015)
Li, Cao (June 29, 2009). “Anger and tears over collapse of building”, China Daily
Li, Cao (July 4, 2009). “Cost-cutting not cause of tower’s fall”, China Daily
Li, Cao (July 8, 2009). “Fatal collapse rings alarm bells for developers”, China Daily
Nosowitz, Dan (June 30, 2009) “Entire New 13-Story Building Tips Over in Shanghai”, Gizmodo, <**http://gizmodo.com/5304233/entire-new-13-story-building-tips-over-in-shanghai/**> (October 6, 2015)
Xinran, Li; Chen, Lydia; and Shen, Wu (June 29, 2009). “Authorities put 9 under control over fatal building collapse”, ShanghaiDaily.com <**http://www.shanghaidaily.com/sp/article/2009/200906/20090629/article_405753.htm**> (October 6, 2015)