Impact of Foundation Pit Excavation: Real-time Monitoring Required for Subsequent Construction

2013-10-04 578 0人评论
      Suspected cause: piling at an adjacent construction site has led to ground settlement of nearly 200-300 square meters in the Shangnan Yazhu residential community in Sanshui, with the most severe subsidence exceeding 40 centimeters and maximum displacement cracks in the foundation pit reaching about 10 centimeters.

Currently, a parking lot in the community is unusable, multiple water pipes have ruptured, and some owners have complained about concerns that the building structure may be affected, posing a risk to personal safety.

  Owners: Settlement occurred after piling next door

  Shangnan Yazhu Community is located on Nanfeng Avenue in Sanshui and was delivered for use in 2010. It currently has nearly 200 households.

  "The ground had always been fine before. Last month, the construction site next door started piling with great noise and deep piles, and then the ground behind the building began to subside," said owner Xiang Ge in a complaint yesterday. He said the initial settlement and foundation pit displacement were not obvious, but later nearly 200-300 square meters of ground settled. "Cars can't even enter the parking lot; the cracks are wide enough to swallow an adult's foot—it's too dangerous." Xiang Ge measured the settlement with a ruler; the deepest part exceeded 40 centimeters, and the maximum displacement crack in the foundation pit was about 10 centimeters.

  "I'm really worried the ground will continue to sink." Many owners complained that settlement occurred less than three years after moving in, and they fear it will cause huge harm to the structural safety of the buildings and endanger personal safety. They hope the developer and the construction party can provide a solution.

  At the scene, the reporter saw an excavator working at the construction site separated from the community by a wall. The ground of the community near the site had settled overall, the foundation pit had displaced, large gaps had appeared between the walls and the ground, and multiple cracks had appeared on the ground, the longest about 50 meters. As a result, multiple water pipes in the community had ruptured, and some exterior wall tiles had fallen off.

  Developer: No major safety hazards have been caused yet

  In response, the developer of Shangnan Yazhu said that after receiving complaints from owners, it had invited the construction unit, owner representatives, and a third-party monitoring unit to a meeting, and all parties initially reached a consensus: at this stage, the ground settlement and foundation pit displacement at Shangnan Yazhu are within a controllable range and have not yet caused major danger to the structural safety of the community.

  However, the developer promised to continue paying close attention to the settlement issue in the community and to study emergency plans with all parties. It will promptly coordinate with the construction party to address the road sections with relatively large settlement and will regularly publish ground settlement information to the owners. But the developer has not yet clearly stated whether the road settlement and cracking were caused by piling at the adjacent construction site.

  Statements from various parties

  Construction unit

  The community had pre-existing settlement; worsening may be related to heavy rain

  The construction site adjacent to Shangnan Yazhu is located at No. 9 Nanfeng Avenue, Sanshui. Yesterday, the relevant person in charge of the construction unit, Guangdong Wanyuan Construction Engineering Co., Ltd., said that excavation for a one-story basement began on August 7, with a foundation pit area of 2,000 square meters and a maximum excavation depth of about 4.1-5.25 meters. To prevent disputes with Shangnan Yazhu, the company commissioned Foshan Mingzheng Building Testing Co. in advance to conduct monitoring from earthwork excavation to backfilling. On August 3, the testing company conducted on-site inspection and evidence collection. The report showed that the community indeed had pre-existing ground settlement and cracking with old traces, but the deepest subsidence was about 10 centimeters, not as severe as the current 40-centimeter settlement.

  "Before construction started, ground settlement and cracking had already appeared in Shangnan Yazhu Community," the person in charge said. This was due to problems with the community's own underground water pipe installation, which had leaked for a long time. The current ground settlement and cracking in the community are more severe because of frequent heavy rain recently, and are unrelated to construction piling.

  Quality supervision department

  Foundation pit excavation has an impact; real-time monitoring required for subsequent construction

  According to the project's supervision unit, the original data and records of the third-party monitoring party invited by the construction unit were not complete enough, especially lacking objective records of settlement on the roads of the surrounding community. On-site inspections found new cracks near the construction wall of the community.

  In response, the Sanshui quality supervision department also stated that the under-construction project does indeed have varying degrees of impact on the surrounding environment, and that foundation pit excavation and groundwater loss have caused road subsidence in the community. In subsequent construction, the construction party must carry out real-time monitoring and promptly report reliable monitoring data to facilitate problem resolution.

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