| 潜孔锤引孔施工技术在含硬岩层预制桩施工中的应用问题探讨（一） | |||
| 广州振宇潜孔锤科技分享~ 风动潜孔锤应用于 含块石、 孤石、中风化和微风化硬岩 或夹层的预制桩沉桩施工 成功解决了复杂地层管桩沉桩难题  大直径风动潜孔锤引孔技术在含硬岩层预制桩施工中的应用讨论 Application of large diameter pneumatic DTH hammer drilling technology in rock hard prefabricated piles construction 大直径风动潜孔锤应用于含块石、 孤石、中风化和微风化硬岩或夹层的预制桩沉桩施工成功解决了复杂地层管桩沉桩难题。 The large diameter pneumatic DTH hammer has applied in rock hardness with pebble, boulder, moderated-weathered layer and micro-weathered layer or prefabricated pile construction, which successfully solved complicated layer pile sinking problems. 风动潜孔锤钻进是以压缩气体为动力介质，并以空气作为循环介质的冲击回转钻机方法。它与其它钻进方法相比，具有以下一些特点： Features of Pneumatic DTH hammerPneumatic DTH hammer is an impacting rotary drilling method that puts compressed air as its power medium, and air as its circulating medium. Compared with other drilling methods, it has the following features. 1. 应用范围广风动潜孔锤能应用于各种地层，特别是破碎、易坍塌难钻进地层；也适用于干旱缺水地区。Wide applicationPneumatic DTH hammer can be applied in various layers, especially in crushing and easily collapsing layer, it also applied in drought and water shortage areas. 2. 钻进效率高由于风动潜孔锤冲击功大，钻进时能形成体积破碎，碎岩效率高，孔底干净，无重复破碎，加上回转的剪切，钻进效率比普通方法高。据生产实践证明，其钻进效率比金刚石回转钻进高3~5倍。High drilling efficiencySince pneumatic DTH hammer has the characteristics of large impact energy, crushing volume, high drilling efficiency, clean bottom hole, non-repeated crushing and rotary cutting, so its drilling efficiency higher than normal methods. According to practice, its drilling efficiency is 3 or 5 times higher than that of diamond rotary drilling 3. 钻孔质量好潜孔锤钻进可以减少钻头上的钻速差，同时，钻进时钻机钻速低，钻具与孔壁碰撞机会少，减少了附加力矩，减少了岩石各项异性的影响，也减少了破碎岩石或倾斜岩层的影响。因此，钻孔垂直度好，孔壁完整，稳定，钻孔质量高。 High quality Pneumatic DTH hammer can reduce drilling speed difference, meanwhile, as the drilling rig has a slow drilling speed, and drilling tool has less chance of colliding with the hole wall, which reduce additional torque and influence of rock isomerism, as well as crushing rock and deviation. Therefore, drilling hole has a good verticality, stable hole wall and qualified drilling. 预应力混凝土管桩是目前应用最广泛的、 较成熟的桩基， 因预应力管桩桩体强度高、 施工管理简单、 施工现场文明、 施工速度快等优点， 而被广泛应用于沿海地区的基础工程中。 随着管桩应用的普及，管桩难以穿越复杂地层尤其是块石、孤石、 中风化和微风化硬岩或夹层地层，成为管桩应用的一大障碍。 Prestressed concrete pipe is the most widely used and mature pile foundation for its high strength, easy construction management, civilized construction site and fast speed, thus widely applied in foundation project in coastal areas. With the popularity of tubular pile, it is difficult to drill through the complicated layers, especially pebble, boulder, moderated-weathered layer and micro-weathered layer or Interlayer layer, which has been a major problem in this field. 目前，国内针对管桩引孔技术主要有两方面的研究： 非取土引孔沉桩技术和取土引孔沉桩技术。 非取土引孔沉桩技术是指通过特殊的方法改变土的物理力学性质，以降低土的侧靡阻力和抗剪强度，满足沉桩需要，该技术包括深层搅拌引孔法、高压旋喷引孔法和射水引孔法等工艺 ：取土引孔沉桩技术是指通过钻孔的方式减少沉桩阻力，以达到沉桩的目的。该方法主要包括常规钻孔引孔法、长螺旋 引孔法、 潜孔锤引孔法等工艺。 Recently, there are two aspects studies tubular pile drilling technology in China: non-borrowing hole digging pile technology and borrowing hole digging pile technology. The non-borrowing hole digging pile technology refers to change Physical and Mechanical Properties of Soil through special method to reduce its lateral resistance and shear strength to meet its demand. It includes deep mixing hole method, high pressure rotary jetting method and water jetting method, etc. The borrowing hole digging pile technology means through rock drilling method to reduce sinking piling resistance to achieve the aim, it includes regular drilling method, long spiral drilling method and DTH hammer drilling method. 预应力混凝土管桩被广泛的应用 近年来，南方省市沿海滩涂和软土地区，高层或小高层建筑的基础多采用预应力管桩基础，以其质量可靠、施工工期短、工程造价低、技术可行性高等优点，在较短的时间内被广泛的应用。 In recent years, PHC has been widely used in coastal beaches and soft soil in southern provinces, as well as high building or low building foundations. It was been widely applied in a short time for its reliable quality, short construction time, low cost and high feasibility. 常见问题 浮桩、偏桩 然而由于沿海地区场地软弱地基情况又十分普遍，一般地下水位较高，地质均匀性较差而且淤泥层广泛分布，深度较深，一些地方，软塑，流塑状淤泥层厚达数米至十几米，较厚的淤泥层极易产生土体侧向位移及隆起，造成大面积浮桩、偏桩质量事故，当在此类土层采用预应力管桩基础时，由于地基土层过软，其对管桩桩身上段的保护作用较弱，严重者甚至失去对桩身的保护，并且管桩属挤土桩，施工速度快，软土地区大量施打后，土体超孔隙水压力较大，当进行土方施工时，如未能采取有效的措施对管桩进行保护，容易产生浮桩和掉桩的现象，影响预应力高强混凝土管桩的一次成桩率，进而影响主体结构的安全性，一旦发生事故就容易造成灾难性后果。 However, because coastal area has normally weak foundation and high groundwater level, uneven geological condition and silt layer is deeply and widely distributed, in some areas, as well as soft plastic and plasticity silt has achieved more than ten meters, so thicker silt layer is easy to cause lateral displacement and uplift of soil, which resulting in large area floating pile and partial pile quality accident. Therefore, when PHC is used in this kind of layer, since foundation layer is too weak, so it has weak protection to pile, even lost protection to the whole pile. Moreover, pile belongs to soil compaction pile, it has a fast speed, but after construction to soft soil, the excess pore water pressure of soil is large. When construction, if effective measures cannot be taken to protect it, well then floating pile and falling pile will happen, thus affecting the primary pile formation rate of PHC, which in turn affects the safety of the main structure. Once an accident occurs, it is easy to cause catastrophic consequences. 通常采用顶推法进行补救  同时，根据以往的工程经验，管桩如果出现偏桩，通常采用顶推法进行补救，处理费用达3000元/根；如果出现浮桩，通常需进场机台重新进行复压，机台机场费约180000元。后期的补救处理费用更高，甚至可能无法补救成为废桩，直接影响工程经济效益。而且如果工程施工中未能一次成桩，造成后期补救返工，将会直接影响节点工期，进而影响工程的主线工期。 Meanwhile, according to experience, if pile happens deviate, incremental launching will be taken to remedy, and processing cost is 3000 yuan; if happen floating pile, then need to enter the machine to re-compress, the fee is about 180,000 yuan. Later remediation costs are higher, even fails to remedy as waste piles, which directly affecting the economic benefits of the project. If fail to formation will cause later remediation, which directly affects construction time, thus further affect major line of project. |
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