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1、外文出处Knight M A, Mitchell R J. Modeling of light non-aqueous phase liquid (LNAPL) releases into unsaturated sand .Canadian Geotechnical Journal, 1996,33, 33 :913-925 . Bored pileSummary Drill ( flushing, dig ) pile from the nineteen sixties, beginning in Henan province Nanyang region since the develo

2、pment application, because of its many advantages, has been widely used in soft soil, loess, including soil, expansive soil and other special types of foundation and industrial, civil, municipal, railway, highway, port and other types of Engineering practice. And precast pile, bored pile constructio

3、n of no noise, no vibration, on the surrounding buildings and small environmental impact, pile diameter, buried deep, large bearing capacity. Chinas drilling pile maximum diameter of pile has reached 4000mm, maximum deep pile has reached 104m, and the steel pipe pile maximum diameter of 1200mm, the

4、largest pile of prestressed concrete pipe pile with deep 83m, maximum diameter of 1300mm, the biggest pile depth 40m. Along with our country socialist construction is booming, with high-rise buildings, large span bridges on the rise, the bearing capacity of pile foundation with higher requirements.

5、Large diameter bored pile therefore gets rapid development, pile length and pile diameter also do bigger more. However, in the existing various methods of pile, bored pile has many advantages and is widely used in construction, but it is hard to avoid the impact of mud, which not only reduces the be

6、aring capacity of pile expectations, but also caused a serious waste of materials. Manual hole digging pile is difficult to achieve greater depth, its bearing capacity is also difficult to just as one wishes. In view of bored pile in this situation, how to improve the pile construction technology le

7、vel, make the input material to be more reasonable to use, so as to greatly increase the bearing capacity of single pile in engineering field, have become hot issues in recent years.The introduction of bored cast-in-place pile Perfusion pile refers to the construction site by mechanical drilling, st

8、eel pipe soil compaction or human mining method in the foundation pile hole in form, and on its inner placed reinforcement cage, concrete made with different pile, drilling method, grouting pile can be divided again for cast-in-place pile, bored pile and digging several types of piles. Bored pile by

9、 pile into the definition and classification of a kind of pile.The characteristics of bored cast-in-place pile1、And sinking pile of hammering method, construction noise and vibration is smaller2、To construct than the precast pile of large diameter of pile3、In all kinds of ground can be used4、The con

10、struction quality of the pile bearing capacity influence5、Because the concrete is in the mud perfusion is difficult to control, so the quality of concreteBored pile construction method Percussion drilling, punching grabbing drilling and rotary drilling hole can adopt slurry wall construction method.

11、 The construction process is: site formation, slurry preparation, buried tube and laying work platform rig and positioning, drilling, hole cleaning and inspection of hole quality and lower steel cage, underwater concrete perfusion to pull out the barrel to check quality. Construction sequence： (1) t

12、he construction preparation Construction preparation comprise: selecting drill, drill, layout. Construction of bored pile drilling rig is the main equipment, according to the geological conditions and various drilling machine applied to select conditions (2) drilling machine installation and positio

13、ning Istallation of drilling machine based if not stable, easy to produce in the drilling machine construction, pile and pile inclined inclined eccentric and other adverse effects, therefore requires the installation of foundation stability. On the formation of softer, sloping ground, be bulldozed,

14、the pad plate or tie reinforcement. In order to prevent the pile position allowed, construction is very important to the set the center position and the correct installation of drilling machine, the rig drilling machine, first use of the power drill and near the cage with the drill pipe, moving roug

15、hly position, and then Jack rack jacking, accurate positioning, so that the lifting pulley, drill bit or fixed drill hole cards and casing center in a vertical line, in order to ensure the verticality of the drilling rig. Drilling position deviation is not more than 2cm. Aligned with the pile locati

16、on, with sleeper flat drill beam at the top of the tower, and symmetrical to the drill axis pulling cable wind rope. (3) buried tube Underground water level below the Kong Bitu under the hydrostatic pressure to the hole collapse, and even the phenomenon of flow of sand. If you can keep the borehole

17、wall high underground water head, increase the hole hydrostatic pressure, to prevent collapse hole, hole wall. Casing in addition to play this role, at the same time, good isolation of surface water, ground, protecting the orifice pile hole drill guide fixed (4) slurry preparation Drilling mud is co

18、mposed of water, clay ( bentonite ) and an additive composition. A floating drilling waste slag cooling the drill bit, drill, lubrication, increasing hydrostatic pressure, and in the hole wall to form a slurry, partition within the bore to prevent seepage, the hole collapse effect. Modulation of the

19、 drilling mud and circulating purifying mud, should be based on the drilling method and formation conditions to determine the slurry consistency, slurry consistency should be considered stratigraphic changes or operational requirements of motor control, the mud is too thin, small, poor effect of eli

20、mination of slag wall; slurry is too thick will weaken bit impact function, reduce drilling speed. (5) drilling The borehole is a key working procedure, in construction must strictly according to the operating requirements, in order to ensure drilling quality, attention must be given to the hole qua

21、lity, must be opposite for this good midline and verticality, and pressed well casing. Must pay attention in the construction are continuously added and pumping the slurry slag ( impact type ), but also at any time to check whether there is deviation phenomenon into hole. Using the impulse or clamsh

22、ell type drilling machine construction, soil due to vibration and impact near the adjacent hole stability. So the drilled hole should be timely cleaning hole, decentralization and pouring underwater concrete reinforcing cage. Drill order should also be practical to plan, should not only guarantee a

23、pile hole construction does not affect the last pile hole drill, and the moving distance of not too far and mutual interference. (6) the hole cleaning The drilling depth, diameter, location and shape of hole is directly related to the quality of pile and pile body black. Therefore, in addition to dr

24、illing process close observation supervision, to meet the design requirements in drilling hole depth, with deep, hole, pore shape, pore size and other inspections. In the end hole inspection in full compliance with the design requirements, shall immediately proceed to bottom hole cleaning, avoid it

25、too long that mud settling, caused by borehole collapse. For friction pile when the hole wall is easy to collapse, in underwater concrete perfusion before the sediment thickness of not more than 30cm; when the hole wall is not easy to collapse, not more than 20cm. For the post, in water or shoot the

26、 breeze, sediment thickness less than 5cm. Hole cleaning method is to use different and flexible application of drilling rig. Usually you can use normal circulation rotary drilling rig, reverse circulation rotary machine vacuum suction machine and slag pumping cylinder hole cleaning. The mud suction

27、 machine hole cleaning, required equipment, convenient operation, hole cleaning is thorough, but unstable in the soil should be used cautiously. Its principle is to use compressor generates high pressure air into a suction dredge pipeline will mud blowing. (7) pouring underwater concrete After finis

28、hing hole, can be prefabricated reinforcement cage hanging vertically into the hole, positioning to be fixed, and then using a perfusion catheter concrete, pouring concrete dont interrupt, or prone to the phenomenon of broken pile.Effect of bored pile bearing performance factors In the construction

29、process, construction machinery, due to geological effects, often caused by pile soil ( weak layers ), the thickness of 0.2 0.5m, thick and up to 1m. Especially in soft soil with mud, drilling, hole bottom sediment is inevitable; even after careful cleaning hole, the hole cleaning after and before c

30、oncrete, will precipitate some sediment, and in drilling process, widespread presence on the hole wall and the hole bottom soil disturbance. All of these affect the bearing capacity of bored pile play. Pile static load test show that, bored pile end bearing capacity of only the ultimate load of the

31、15% 35%, the side resistance and tip resistance of the existing synchronization phenomenon. Give full play to the role of lateral friction resistance is only a few millimeters of the displacement of pile top, to give full play to the role of tip resistance of pile diameter, needed to reach 10% - 30%

32、 of the displacement of pile top. Such a large displacement in engineering is not allowed. Pile side friction resistance to damage, and the damage limit is reached, and the end resistance cannot get sufficient play, its potential is great. This is the ultimate bearing capacity of bored pile is not t

33、o cause. Research shows that, at the bottom of pile soil exists, not only affects the tip resistance of the play, also make the side friction resistance loss. The existence of weak interlayer of pile, the pile body and the soil friction between the nature of the change, the friction between pile and

34、 soil by load transfer, is very bad. This is the bored pile bearing not tall benefit is another reason.Improve the bearing capacity of Bored Piles According to the bearing capacity of bored pile is not to cause analysis, engineering and some improving bearing capacity of pile foundation of the metho

35、d, mostly around the elimination of pile bottom sediment, a pile of weak interlayer. (1)pre loading method in advance of the pile bottom for preloading, the pile soil compaction, improve the bearing capacity of piles. But time-consuming, costly, and not easy to implement. (2) extending end bearing a

36、rea. The belled pile, in the past used in engineering is more, but on the bottom of pile soil are still incapable of action. (3) sand lining pile technology : the method for cast-in-place pile, construction, use double sleeve around the pile in sand filling, become sand set of about 3 10cm, sand set

37、 can improve the lateral wall of the friction resistance of pile. (4)Grouting technology:routing technology grouting method can be divided into the first grouting and grouting method. The first method of grouting is drilled in the Kong Zhuangcheng hole and before concrete grouting, the nozzle pipe i

38、nto the hole bottom is inserted into the soil, spraying slurry, so that at the bottom of pile soil mixed with cement, then pile concrete. Pile cap Cap refers to bear, distribution from pier to carry the load on pile top, set to connect all the top of the pile of reinforced concrete platform. Cap is

39、piles and columns or piers contact part. The root cap, even ten piles are linked with the formation of the pile foundation. Cap for high pile cap and pile caps: low pile cap generally buried or partially buried in the earth, high pile cap generally above the ground or water. High rise pile cap havin

40、g a free length, the surrounding supporting body to withstand horizontal load. Pile stress situation is extremely unfavorable. Pile internal force and displacement under the action of external force than the same level of low pile cap to be big, the stability is poor because of low pile cap. High ri

41、se pile cap is generally used for port, wharf, marine engineering and bridge engineering. Low pile cap is generally used in industrial and civil buildings. Pile head generally into platform 0.1 meters, and a reinforced anchor into the cap. Platform to build on the columns or piers, forming a complet

42、e power transmission system. In recent years due to the large diameter bored pile, pile rigidity, strength is big, so high pile in bridge foundation construction has been widely used.灌注桩概述钻（冲、挖）孔灌注桩，从20世纪60年代初在河南省南阳地区研制应用以来，因其具有众多的优点，已广泛应用于包括软土、黄土、膨胀土等特殊土在内的各类地基和工业、民用、市政、铁路、公路、港口等各类工程实践中。和预制桩相比，钻孔桩施

43、工时无噪声、无振动，对周围建筑及环境影响小，桩径大，入土深，承载力大。据文献1统计，我国钻（冲）孔桩最大桩径已达到4000mm，最大桩深已达104m，而钢管桩最大桩径为1200mm，最大桩深为83m，预应力混凝土管桩最大桩径为1300mm，最大桩深为40m。随着我国社会主义建设事业的迅速发展，伴随着高层建筑，大跨度桥梁的兴起，对桩基础的承载力有了更高的要求。大直径灌注桩因此得到快速发展，桩长和桩径也越做越大。然而，在现有的各种成桩方法中，钻孔桩虽有许多优点而被广泛采用，但在施工中却难以避免泥浆的影响，这不仅降低桩承载力的期望值，而且造成材料的严重浪费。人工挖孔桩因难以达到更大的深度，其承载力也

44、难尽如人意。鉴于灌注桩的这种现状，如何提高桩的施工工艺水平，使投入的材料得到更为合理的利用，以大幅度提高单桩承载力，就成为工程界备受关注的热点问题。 钻孔灌注桩的简介灌注桩是指在工程现场通过机械钻孔、钢管挤土或人力挖掘等手段在地基土 中形成桩孔，并在其内放置钢筋笼、灌注混凝土而做成的桩，依照成孔方法不同，灌注桩又可分为沉管灌注桩、钻孔灌注桩和挖孔灌注桩等几类。钻孔灌注桩是按成桩方法分类而定义的一种桩型。钻孔灌注桩的特点1、与沉入桩中的锤击法相比，施工噪声和震动要小的多； 2、能建造比预制桩的直径大的多的桩； 3、在各种地基上均可使用； 4、施工质量的好坏对桩的承载力影响很大； 5、因混凝土是在

45、泥水中灌注的，因此混凝土质量较难控制。钻孔灌注桩施工方法 冲击钻孔，冲抓钻孔和回转钻削成孔等均可采用泥浆护壁施工法。该施工法的过程是：平整场地泥浆制备埋设护筒铺设工作平台安装钻机并定位钻进成孔清孔并检查成孔质量下放钢筋笼灌注水下混凝土拔出护筒检查质量。施工顺序： （1）施工准备施工准备包括：选择钻机、钻具、场地布置等。钻机是钻孔灌注桩施工的主要设备，可根据地质情况和各种钻孔机的应用条件来选择。 （2）钻孔机的安装与定位 安装钻孔机的基础如果不稳定，施工中易产生钻孔机倾斜、桩倾斜和桩偏心等不良影响，因此要求安装地基稳固。对地层较软和有坡度的地基，可用推土机推平，在垫上钢板或枕木加固。 为防止桩位

46、不准，施工中很重要的是定好中心位置和正确的安装钻孔机，对有钻塔的钻孔机，先利用钻机的动力与附近的地笼配合，将钻杆移动大致定位，再用千斤顶将机架顶起，准确定位，使起重滑轮、钻头或固定钻杆的卡孔与护筒中心在一垂线上，以保证钻机的垂直度。钻机位置的偏差不大于2cm。对准桩位后，用枕木垫平钻机横梁，并在塔顶对称于钻机轴线上拉上缆风绳。 （3）埋设护筒 钻孔成败的关键是防止孔壁坍塌。当钻孔较深时，在地下水位以下的孔壁土在静水压力下会向孔内坍塌、甚至发生流砂现象。钻孔内若能保持壁地下水位高的水头，增加孔内静水压力，能为孔壁、防止坍孔。护筒除起到这个作用外，同时好有隔离地表水、保护孔口地面、固定桩孔位置和钻

47、头导向作用等。 (4)泥浆制备 钻孔泥浆由水、粘土(膨润土)和添加剂组成。具有浮悬钻渣、冷却钻头、润滑钻具，增大静水压力，并在孔壁形成泥皮，隔断孔内外渗流，防止坍孔的作用。调制的钻孔泥浆及经过循环净化的泥浆，应根据钻孔方法和地层情况来确定泥浆稠度，泥浆稠度应视地层变化或操作要求机动掌握，泥浆太稀，排渣能力小、护壁效果差；泥浆太稠会削弱钻头冲击功能，降低钻进速度。 (5)钻孔 钻孔是一道关键工序，在施工中必须严格按照操作要求进行，才能保证成孔质量，首先要注意开孔质量，为此必须对好中线及垂直度，并压好护筒。在施工中要注意不断添加泥浆和抽渣(冲击式用)，还要随时检查成孔是否有偏斜现象。采用冲击式或冲

48、抓式钻机施工时，附近土层因受到震动而影响邻孔的稳固。所以钻好的孔应及时清孔，下放钢筋笼和灌注水下混凝土。钻孔的顺序也应实事先规划好，既要保证下一个桩孔的施工不影响上一个桩孔，又要使钻机的移动距离不要过远和相互干扰。 (6)清孔 钻孔的深度、直径、位置和孔形直接关系到成桩质量与桩身曲直。为此，除了钻孔过程中密切观测监督外，在钻孔达到设计要求深度后，应对孔深、孔位、孔形、孔径等进行检查。在终孔检查完全符合设计要求时，应立即进行孔底清理，避免隔时过长以致泥浆沉淀，引起钻孔坍塌。对于摩擦桩当孔壁容易坍塌时，要求在灌注水下混凝土前沉渣厚度不大于30cm；当孔壁不易坍塌时，不大于20cm。对于柱桩，要求在射水或射风前，沉渣厚度不大于5cm。清孔方法是使用的钻机不同而灵活应用。通常可采用正循环旋转钻机、反循环旋转机真空吸泥机以及抽渣筒等清孔。其中用吸泥机清孔，所需设备不多，操作方便，清孔也较彻底，但在不稳定土层中应慎重使用。其原理就是用压缩机产生的高压空气吹入吸泥机管道内将泥渣吹出。 (7)灌注水下混凝土 完孔之后，就可将预制的钢筋笼垂直吊放到孔内，定位后要加以固定，然后用导管灌注混凝土，灌注时混凝土不要中断，否则易出现断桩现象。影响钻孔灌注桩承载性能的因素在施工过程中，由于地质、施工机械的影响，常造成桩底虚土（软弱层