| In recent years, with the rapid development of economy and city construction, especially big and middle cities of our country, top and super-tall buildings have developed very fast. At the same time, more and more underground engineering have shown. Normally, the deeper basement is designed in the high buildings whose sizes have extended thousands of squara meters in area,40meters in deepness.The proposed Landscape&kun jade commercial building is located in the interchange of the Renmin middle road and the Zhengfu street in the downtown of Chengdu. The building,102.2m height, is commercial and residential building with the first floor podium,32～33floors and3-layer basement..This paper sums systematically up various methods of supporting foundation pit at home and abroad, and discusses the main factors affecting the stability of foundation pit firstly. Then taking Landscape&kun jade commercial building as a case, the investigation of the hydro-geological and engineering geological conditions of the foundation pit have been carried out. Based on indoor-outdoor tests and investigation, the supporting and dewatering scheme for pit are proposed Finally, according to the monitoring data, the informatization construction and feedback analysis were evaluated. In this paper, the main results are as follows:(1) The geomorphic unit of the build belongs to minjiang river water system level1order, adjacent to the two terrace. Formations form top to bottom are quaternary holocene artificial fillled soil layer(Q4ml), quaternary holocene alluvium(Q4al) of the silty clay, silt, sand and pebble soil. Excavation depth of foundation pit is15.56m and dewatering depth is21m.(2) The dewatering method is12tube wells with600mm well diameter,27.5m the depth,17.5m length of upper part of the well and10m length the lower part of the well.(3) According to the engineering geological conditions, the prestressed anchor piles in two sections was designed for supporting the foundation pit. The No.1-44#are "A" pile and No.45-84#is "B" pile.(4) The section of A-pile:the length of pile is20.65m, spacing between the piles is2.0m, the core diameter of pile is1.2m, the core and wall protection material of the piles are C25and C20concrete separately. Two rows4Φ15.24prestressed anchor cable are designed at stake of-7.0m and-10.0m with14m anchor length. At the position of-1m stake, one row grouting bolt is done with3～6m long and2.0m spacing.(5) The section of B-pile:the length of pile is20.65m, spacing between the piles is2.5m, the core diameter of pile is1.0m, the core and wall protection material of the piles are C25and C20concrete separately. Two rows4Φ15.24prestressed anchor cable are designed at stake of-5.0m and-80.0m with12m or13.5m anchor length.(6) The monitoring scheme of the foundation pit are proposed. It enforces the information construction, furthermore benefits for finding problems, identifying the reasons and formulating corresponding measures to guide the next step of construction in order to ensure the safety of foundation pit and surrounding buildings. According to monitor results of the settlement and horizontal displacement, the dewatering and supporting design scheme in this foundation pit are considered to be feasible. |
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