二元結構地層基坑深井降水工法.pdf

  隨著城市高層建筑的發展，深基坑工程越來越多。由于深基坑設計和施工受到地質、水文、環境、季節、荷載等諸多因素的影響，在二元結構地層條件下，深基坑的主要矛盾是治理地下水的問題，特別是在地下水位高、承壓含水層厚度大、水量豐富的水文地質條件下，如果對地下水治理不當，在開挖過程中極易產生流砂和管涌，影響場區周圍建筑物和市政公用設施的安全。很明顯，一般的降水技術很難達到要求。中建三局建筑技術研究設計院經過幾個工程的實踐、探索，逐步形成了一整套深井降水新技術。在地質巖性構成具有明顯的二元結構沉積韻律，承壓水位距地表僅l~2米，層厚達30米的武漢國際貿易大廈采用了此項新技術獲得成功。并獲中建三局1995年度科技進步一等獎，同時作為武漢國貿主體綜合施工技術的一部分獲1995年中建總公司科技進步一等獎。
1  工法原理
    深井降水是在基坑開挖前，根據基坑面積大小、涌水量等因素，預先在坑內、坑外或坑內外結合，布設一定數量的管井，在管井內安裝深井泵，抽取地下水，達到降低基坑內的地下水位，以利于地下室在干燥條件下順利施工的工藝方法。
2  工法特點
    2．l  降水效果顯著。
    2．2  施工機具簡單多樣，便于選擇。
    2．3  耗資少。
3  適用范圍
    3．l  本工法適用于涌水量較大，滲透系數較大，長江流域一級階地上二元結構地層的基坑降水。
3．2  本工法對大面積、深基坑尤為適用。
4  設計要點
4．l  降水井
4．1．l  管井結構
合理的管井結構，要求達到能使地下水暢通地流入井內，同時
With the development of urban high-rise buildings, more and more deep excavation. As the deep foundation design and construction by the geology, hydrology, environment, season, load, and many other factors, geological conditions in the dual structure, the deep excavation of the main contradiction is the issue of groundwater management, especially in the high water table, thick confined aquifer, water-rich hydrogeological conditions, groundwater treatment if properly produced in the excavation process is extremely easy flow of sand and piping, influence field area around the buildings and the safety of public utilities. Obviously, the general precipitation are difficult to meet the requirements. Building technology in the construction of three Research and Design Institute Board through several projects the practice, exploration, and gradually formed a set of deep well dewatering technology. Lithologic composition in geological structures with significant deposition of binary rhythm, Pressure Water Jude Biao only l ~ 2 meters, 30 meters thick Wuhan International Trade Building, using the success of this new technology. And was in the construction of the Third Bureau of Science and Technology Progress Award for the year 1995, while the main body of Wuhan International Trade as part of an integrated construction technology by 1995, China State Science and Technology Progress Award.
Engineering Principle 1
    Deep well in the excavation before the pit area according to size, discharge and other factors, in advance of the pit, pit pit outside or inside and outside the combination of laid a number of tube wells, tube wells installed in the deep well, pumping of underground water, to reduce groundwater within the excavation, in order to facilitate the smooth basement construction in dry conditions, the process method.
2 Characteristics of Workers Act
    2. l precipitation effect is remarkable.
    2.2 Construction of simple machine and diverse, easy to choose.
    2.3 cost less.
3 Scope
    3. l The construction method applies to discharge large hydraulic conductivity is high, the Yangtze River basin level terraces dual structure of the foundation pit formation.
3.2 The construction method for large area, especially for deep excavation.
4 design points
4. l dewatering well
4.1. l tube well structure
Rational structure of tube-wells, required to enable the smooth flow of groundwater into the wells, while

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