Case study on the influence of soft clay addressing continuously retaining wall in deep excavation

Deep excavations in soft-clay layer on sloped bedrock often leads to lateral displacement on retaining structures and uneven settlement due to unbalanced pressure generated from excavation. A construction project for which an excavation was complete in soft clay layer on sloped bedrock in Taipei City was adopted in the study. It is learned from the observation logs of the studied case that a significant difference exists in the lateral displacement of diaphragm wall and settlement between up and down-slope sides of sloped bedrock. Deep excavation is in fact profoundly complicated interaction between excavation strutting and soil. In general practice, the design of excavation is frequently simplified as a 2D strain behavior. However, the actual excavation on sloped bedrock is quite different from 1D or 2D simulation in a symmetric manner. Therefore, 2D finite element analysis program, PLAXIS, is introduced for the analysis on the behaviors of soil clay layer on sloped bedrock in excavation. The result is compared with onsite observation data, including displacement of retaining wall, settlement, axial loads of struts and others. The result of retaining wall displacement analysis is found consistent with the trend derived from onsite observation, which is possible for reference of similar engineering analyses and designs in the future.

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Penggunaan Dinding Silang Pada Galian Dalam Di Tanah Sangat Lunak: Studi Kasus Proyek Apartemen DI Jalan Kebun Sirih Jakarta

Jurnal Muara Sains, Teknologi, Kedokteran dan Ilmu Kesehatan ◽

10.24912/jmstkik.v4i2.7090 ◽

2020 ◽

Vol 4 (2) ◽

pp. 257

Author(s):

Oktaffian Widjaja ◽

Chaidir Anwar Makarim

Keyword(s):

Retaining Wall ◽

Soft Soil ◽

Soft Clay ◽

Good Choice ◽

Cross Wall ◽

Deep Excavation ◽

Top Down ◽

Adjacent Buildings ◽

Clay Deposits ◽

Lateral Resistance

Deep excavation in areas with very soft clay deposits need a good soil retaining system and excavation method. Using a diapraghm wall as a soil retaining system for deep excavation is a good choice can be done. Diapraghm wall is expected to limit the movement that occurs in the retaining walls and avoid leaks that occur in walls, this is needed to minimize damage to adjacent buildings. The top down excavation method by utilizing the basement floor as lateral resistance can be carried out to reduce the movement that occurs on the ground. In very soft soil areas with excavation distances to neighbors very close, the movement on the ground must be limited to minimize damage to adjacent buildings. Cross walls can be used to reduce the movement that occurs on the ground. Analysis of finite element with using the Plaxis program was carried out to investigate the performance of the retaining wall. From the results of the analysis conducted shows that using a cross wall at a location below the raft pile can be reduced the movement that occurs in the retaining wall and the excavation stages can be reduced. Keywords: cross wall; deep excavation; diapraghm wall; very soft soil ABSTRAKGalian dalam pada daerah dengan endapan tanah liat sangat lunak yang cukup dalam diperlukan sistem penahan tanah dan metode galian yang direncanakan dengan baik. Menggunakan dinding dipraghm sebagai sistem penahan tanah untuk galian dalam merupakan pilihan yang dapat dilakukan. Penggunaan dinding diapraghm diharapkan dapat membatasi pergerakan yang terjadi pada dinding dan menghindari kebocoran yang yang terjadi pada dinding penahan tanah karena sistem pengecoran yang saling mengunci dan pertemuan antara panel dinding dapat dipasang waterstop, hal ini diperlukan untuk menghindari kerusakan pada bangunan yang berdekatan dengan daerah galian. Metode galian top down yaitu galian bertahap dengan memanfaatkan lantai besmen sebagai tahanan lateral dapat dilakukan untuk mengurangi pergerakan yang terjadi pada tanah. Pada daerah tanah sangat lunak dengan jarak galian dengan tetangga sangat berdekatan pergerakan pada tanah harus dibatasi untuk meminimalkan kerusakan pada bangunan yang berdekatan. Dinding silang merupakan sistem tahanan lateral yang dapat dipergunakan untuk mengurangi pergerakan yang terjadi pada tanah. Analisis elemen hingga menggunakan program Plaxis 2D dilakukan untuk mengetahui kinerja dinding penahan tanah dan pergerakan yang terjadi. Dari hasil analisis yang dilakukan diperoleh hasil bahwa dengan menggunakan dinding silang yang terletak pada di bawah raft pile dapat menurunkan pergerakan yang terjadi pada dinding penahan tanah dan tahapan galian dapat dikurangi.

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