本科毕业论文某公路桥梁桥双柱式墩基础设计.doc

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1、基础工程课程设计 题目名称: 某公路桥梁桥双柱式墩基础设计学 院： 专业年级： 09土木2班 学生姓名： 学 号： 指导教师： 课程设计第一部分1.1设计任务本设计对象为某公路桥梁，该桥梁的上部结构设计已经完成，本课程设计的任务是完成桥墩基础与地基的设计与检算。要求同学按给定的条件完成相关的设计和计算工作，具体要求如下：1综合分析设计资料，对三种常用的桥梁基础类型（刚性扩大基础、桩基础和沉井基础）的技术合理性进行比较（限于课时，本次课程设计不考虑造价因素），选择较为合理的基础方案。2对选定的基础方案进行详细设计。3初步决定修筑基础的施工方案。4将以上全部成果整理成设计计算说明书和设计施工图。1

2、.2设计资料1.2.1工程概况该桥梁系某I级公路干线上的中桥（单线），线路位于直线平坡地段。该地区地震烈度较低，不考虑地震设防问题。桥梁及桥墩部分的设计已经完成，桥跨由4孔30m预应力钢筋混凝土梁组成。 1.2.2 工程地质和水文地质 地面标高340.8m，最大冲刷线标高335.6m。地基土为中砂，,内摩擦角38o，地基土比例系数m15 000 kN/m4；地基土极限摩阻力 kPa；地基容许承载力370kPa，土的饱和容重 = 19. 50 kN/m3；土的浮容重 = 10.8 kN/m3。 1.2.3墩柱及桩的尺寸 采用双柱式墩（图1)。墩帽盖梁标高351.4m，墩柱顶标高为350.2m，桩

3、顶（常水位）标高为345.2m，。墩柱直径1.50m；桩的直径1.60 m。桩身用C25混凝土；其受压弹性模量MPa；桩的容重 = 25kN/m31.2.4荷载情况 桥墩为单排双柱式，上部结构为30 m预应力钢筋混凝土T梁，桥面宽度7m+21.5m,设计汽车荷载为公路II级，人群荷载标准值为3.0kN/m2。桥梁处于I类环境，下部结构安全等级为二级，以顺桥向计算。图1 双柱式桥墩计算图（标高单位为m，尺寸单位为cm）每一根桩承受荷载为：两跨恒载反力 N1=1451.78 kN盖梁自重反力 N2=401.5 kN系梁自重反力 N3=141.78 kN一根墩柱（直径1.5m）自重N4=220.28

4、 kN 桩每延米自重两跨活载反力 N5=569.10 kN 单跨活载反力 N6=415.18kN车辆荷载反力已按偏心受压原理考虑横向分布的分配影响。在顺桥向引起的弯矩 M=129.15kNm 制动力T=89.50 kN，作用点在支座中心，距桩顶距离为5.867m。纵向风力：盖梁部分W1=2.95kN，对桩顶力臂5.1m；墩身部分W2=2.25kN，对桩顶力臂2.45m；桩基础采用旋转钻孔灌注桩基础，为摩擦桩。桥墩为单排双柱式，上部结构为30 m预应力钢筋混凝土T梁，桥面净宽7m21.5 m,设计汽车荷载为公路2级，人群荷载标准值为3.0kN/m2。以顺桥向计算，计得至盖梁顶的各作用值见表1。1

5、.3 设计依据1中华人民共和国交通部部标准公路桥涵地基与基础设计规范（JTG D63-2007）.人民交通出版社，20072中华人民共和国铁道部标准铁路桥涵地基基础设计规范，TBJ2993赵明华主编，徐学燕副主编基础工程高等教育出版社，20034李克钏主编，罗书学副主编基础工程中国铁道出版社，20005王晓谋主编，基础工程人民交通出版社，2005第二部分 方案设计2.1方案比选(1)对刚性扩大基础基础在外力（包括基础自重）作用下，基底的地基反力为 ，此时基础的悬出部分a-a断面左端，相当于承受着强度为的均布荷载的悬臂梁，在荷载作用下，a-a断面将产生弯曲拉应力和剪应力。当基础圬工具有足够的截面

6、使材料的容许应力大于由地基反力产生的弯曲拉应力和剪应力时，a-a断面不会出现裂缝，这时，基础内不需配置受力钢筋，这种基础称为刚性基础。刚性扩大基础属于浅基础，其埋置深度一般小于5米，对于本工程若采用刚性扩大基础，其须埋于最大冲刷线下不小于1米，刚最小的进置深度为5.7m因此，尽管持力层土层地质良好，考虑浅基础特点故不适合。(2)沉井基础沉井基础适用以下情况a上部荷载较大，而表层地基土的容许承载力不足，扩大基础开挖工作量大，以及支撑困难,但在一定深度下有好的持力层，采用沉井基础与其它深基础相比较，经济上较为合理时；b在山区河流中，虽然土质较好，但冲刷大或河中有较大卵石不便桩基础施工时；c岩层表面

7、较平坦且覆盖层薄，但河水较深；采用扩大基础施工围堰有困难时。综上所述，本工程不须采用沉井基础。(3)桩基础a当建筑物荷载较大，地基上部土层软弱或适宜的地基持力层位置较深，地下水位较高，采用浅基础或人工地基在技术上、经济上不合理；b河床冲刷较大，河道不稳定或冲刷深度不易计算正确，位于基础或结构物下面的土层有可能被侵蚀、冲刷，如果采用浅基础不能保证基础安全时；c当地基计算沉降过大或结构物对基础沉降变形与水平侧向位移较敏感，采用桩基础穿过松软（高压缩）土层，将荷载传到较坚实（低压缩性）土层，以减少建筑物沉降并使沉降较均匀；d承受较大的水平力，需要减少建筑物的水平位移和倾斜时，对稳定性要求较高； e在

8、地震区，可液化地基中， 采用桩基础可增加建筑物抗震能力，桩基础穿越可液化土层并伸入下部密实稳定土层，可消除或减轻地震对建筑物的危害。本工程对水平位移要求严格，本工程中局部冲刷线集位置较深，采用桩基础具有造价低，强度高，沉降量小而均匀，施工较两者简易，综上所述，本工程采用桩基础比较合理。3.1桩长计算由于地基土土层单一，为中密砂砾土，根据地质情况桩长不可确定，应按单桩轴向容许承载力公式反算桩长。采用短期效应组合，除了考虑永久作用外，还需考虑汽车效应和人群效应。按两跨布载考虑Nh=1.0*(N1+N2+N3+N4+Lq+hq)+1.0*N5+1.0*N7=1.0*(1451.78+401.5+14

9、1.78+220.28+(345.2-335.6)*30.16+h*8.44+1.0*569.10=3073.98+8.44h设桩埋入局部冲刷线下深度为h,埋入一般冲刷线下，则计算时取以下数据：桩的设计桩径1.60m,桩周长 =5.03m，=2.01,=0.7, =0.8, =4.0, =370,=10.80(已考虑浮力)，=50，所以得=*(5.03*50*h)+2.01*0.8*0.7*370+4*10.8*(h+5.23)=Nh=3073.98+8.44h 解得h=15.40m 取h=16.0m 桩底标高为319.60 取h=16.0m桩的轴向承载力满足要求。3.2单桩所受外荷载的分配计

10、算墩柱顶外荷载、（按单跨计算） 3.3 换算到局部冲刷线处计算汽车按一跨布载考虑，按承载能力极限状态下作用基本组合的效应组合计算，除汽车荷载效应外还需考虑人群荷载、汽车制动力、风荷载的可变效应。3.4 桩的各参数确定地基土比例系数计算宽度桩的变形参数3.5局部冲刷线以下深度Z处桩身各截面内力计算计算局部冲刷线以下深度Z处的桩身截面弯矩,计算公式：无量纲系数 有附表3、附表7分别查得,计算如下表：0.00.00.000001.00000661.860.20.610.196960.99806715.700.41.220.377390.98617758.320.61.860.529380.95861

11、782.610.82.440.645610.93817786.691.03.050.723050.91324785.111.23.660.761830.85089765.521.44.220.764980.68694668.741.85.490.684880.49889521.862.26.700.531600.32025360.732.67.930.352580.17546214.803.09.150.193050.07595104.293.510.670.050810.0135423.18局部冲刷线以下深度z处横向土抗力计算：无量纲系数由附表1，附表5查得，的计算列表见下表：0.00.02

12、.440661.621000.000.20.612.117791.2908813.310.41.221.802731.0006431.660.61.861.502680.7498125.280.82.441.22370.5372725.661.03.050.970410.3611923.471.23.660.745880.2190819.511.44.220.551750.1079314.531.85.490.25386-0.035723.922.26.700.06461-0.0994-4.832.67.93-0.03986-0.11136-10.143.09.15-0.08741-0.094

13、71-12.023.510.67-0.10495-0.05698-10.79桩身最大弯矩及最大弯矩位置计算：由得 ，由 ，故 , 故 3.6桩底最大压应力验算：桩端最大和最小压应力应满足下式要求：=+569.91则因 , 故则显然： ，满足要求3.7桩柱水平位移验算按承载能力极限状态作用效应基本组合进行验算，根据以上的计算可知桩的局部冲刷线处受力为；墩柱顶上受力为墩柱顶纵向水平位移：，其中桩在局部冲刷线处的水平位移和转角为：水平位移 ：转 角 ：根据分析，摩擦桩且2.5或支承桩且3.5时，几乎为零，可以认为。因为=5.524所以按=4查公路桥涵地基与基础设计规范（JTG D63-2007）得下

14、表： ，满足要求。3.8桩身强度验算与配筋设计按最大弯矩所在截面的内力进行配筋和强度验算最大弯矩发生在地面以下z=1.94m处，该处，桩内竖向钢筋按含筋率0.9%配置：钢筋面积：现选用30根则实际配筋率，纵向钢筋所在圆周半径。截面有效高度1)在垂直于弯矩作用平面内，长细比则在垂直于弯矩作用平面的承载力为：2)在弯矩作用平面内以下采用试算法列表。（）0.711.8420.64831.18751.40453223201.01由上表可见，当时，（）=322mm与设计的=323mm很接近,故取为计算值。3)在弯矩作用平面内的承载力为计算结果表明截面符合承载力要求。4)配置箍筋现取10R235级钢筋满足

15、规范要求。单肢10箍筋的面积，箍筋根据构造要求取箍筋间距为S=200mm截面复核：检查混凝土保护层是否会剥落满足要求，故混凝土保护层不会脱落。3.9裂缝宽度验算根据公路钢筋混凝土及预应力混凝土桥涵设计规范（JTG D62-2004）截面相对界限受压区高度，则构件为小偏心受压，无需验算裂缝宽度。第四部分 施工方案根据工程地质水文地质资料情况该桩基础采用旋挖钻机成孔的方法，钻孔灌注桩是一种质量要求高，施工工序多，须在短时间内连续完成的一种地下隐蔽工程，所以严格控制工序施工质量，保证桩质量。施工工序：（一）准备工作1、准备场地，施工前应将场地平整好，以便安装钻架进行钻孔。场地位于浅水时，宜采用筑岛法

16、。2、埋置护筒，水中筑岛，护筒宜埋入河床面以下1m。在水中平台上设置护筒，课根据施工最高水位，流速，冲刷及地质条件等因素确定。必要时打入不透水层。3、安装钻机，安装时，底架应垫平，保持稳定，不得产生位移沉陷。钻头好钻杆中心与护筒顶面中心的偏差不得大于5cm。4、制备泥浆（二） 钻孔采用正循环进行旋转钻进成孔。在钻孔过程中，始终保持钻孔水位要高出筒外11.5m的水位差和护壁泥浆的要求，钻孔要一气呵成。钻孔过程中加强对桩位、成孔情况的检察工作。（三）清孔及装吊钢筋骨架（四）灌注水下混凝土混凝土应拌合均匀，灌注时连续作业，随时测量和记录孔内混凝土灌注标高和导管入孔长度。（五） 成桩后拔出护筒（六）回

17、填空孔O(_)O谢谢！Many people have the same mixed feelings when planning a trip during Golden Week. With heaps of time, the seven-day Chinese请您删除一下内容，O(_)O谢谢！National Day holiday could be the best occasion to enjoy a destination. However, it can also be the easiest way to ruin how you feel about a place an

18、d you may become more fatigued after the holiday, due to battling the large crowds. During peak season, a dream about a place can turn to nightmare without careful planning, especially if you travel with children and older people. As most Chinese people will take the holiday to visit domestic touris

19、t destinations, crowds and busy traffic are inevitable at most places. Also to be expected are increasing transport and accommodation prices, with the possibility that there will be no rooms available. It is also common that youllwait in the line for one hour to get a ticket, and another two hours a

20、t the site, to only see a tiny bit of the place due to the crowds. Last year, 428 million tourists traveled in China over the week-long holiday in October. Traveling during this period is a matter that needs thorough preparation. If you are short on time to plan the upcoming Golden Week it may not b

21、e a bad idea to avoid some of the most crowded places for now. There is always a place so fascinating that everyone yearns for. Arxan is a place like this. The beauty of Arxan is everlasting regardless of the changing of four seasons. Bestowed by nature, its spectacular seasonal landscape and mounta

22、ins are just beyond word. Arxan is a crucial destination for the recommended travelling route, China Inner Mongolia Arxan Hailar Manzhouli. It is also the joint of the four prairies across the Sino-Mongolian border, where people gravitate towards the exotic atmosphere mixed with Chinese, Russian, an

23、d Mongolia elements. As a historic site for the Yitian Battle, Arxan still embodies the spirit of Genghis Khan. Walking into Arxan, you will be amazed by a kaleidoscope of gorgeous colors all the year round - the Spring azaleas blooming red in the snow, the Summer sea wavering blue in the breeze, th

24、e Autumn leaves painted in yellow covering volcanic traces, and the Winter woods shining white on the vast alpine snowscape. Hinggan League Arxan city is situated in the far eastern area of Inner Mongolia Autonomous Region. Its full name Haren Arxan means hot holy water in the Mongolian language. Ar

25、xan is a tourism city in the northern frontier with a blend of large forest, grand prairies, vast snowfield, heaven lake cluster, thermium, as well as volcanic cluster. It is a rare and unique ecotourism base filled with healthy sunshine, clean air and unspoiled green. Nestled close to the countrys

26、largest virgin forest, and known for its spring and ecological environment, Arxan is marveled at by many tourists as the purest land on earth. You cannot miss out the Autumn of Arxan. It is definitely the best with brightly-colored scenery full of emotions. Autumn in the northern part of the country

27、 comes earlier than the South. A September rain followed by the footprints of Autumn brings more colors to the once emerald green mountain and blooming grassland. Shutterbugs flock to see for themselves the marvel of splendid colors around the mountains and waters, many of whom have travel a long di

28、stance and even camp here only to capture a moment of the nature wonder. The silver birch turns golden, while the larch is still proudly green. You will find yourself drowned in the intoxicating red of the wild fruits as well as the glamour of flowers in full blown. And your heart will be lingering

29、on the woods as its time for the wild fruits to ripe. The picturesque Arxan in Autumn is indeed a fairyland only exists in a dream that satisfies all your fantasies. If itrains heavily on Saturday night, some elderly Chinese will say it is because Zhinu, or the Weaving Maid, is crying on the day she

30、 met her husband Niulang, or the Cowherd, on the Milky Way. Most Chinese remember being told this romantic tragedy when they were children on Qixi, or the Seventh Night Festival, which falls on the seventh day of the seventh lunar month, which is usually in early August. This year it falls on Saturd

31、ay, August 2. Folklore Story As the story goes, once there was a cowherd, Niulang, who lived with his elder brother and sister-in-law. But she disliked and abused him, and the boy was forced to leave home with only an old cow for company. The cow, however, was a former god who had violated imperial

32、rules and was sent to earth in bovine form. One day the cow led Niulang to a lake where fairies took a bath on earth. Among them was Zhinu, the most beautiful fairy and a skilled seamstress. The two fell in love at first sight and were soon married. They had a son and daughter and their happy life w

33、as held up as an example for hundreds of years in China. Yet in the eyes of the Jade Emperor, the Supreme Deity in Taoism, marriage between a mortal and fairy was strictly forbidden. He ordered the heaven troop to catch Zhinu back. Niulang grew desperate when he discovered Zhinu had been taken back

34、to heaven. Driven by Niulangs misery, the cow told him to turn its hide into a pair of shoes after it died. The magic shoes whisked Niulang, who carried his two children in baskets strung from a shoulder pole, off on a chase after the empress. The pursuit enraged the empress, who took her hairpin an

35、d slashed it across the sky creating the Milky Way which separated husband from wife. But all was not lost as magpies, moved by their love and devotion, formed a bridge across the Milky Way to reunite the family. Even the Jade Emperor was touched, and allowed Niulang and Zhinu to meet once a year on

36、 the seventh night of the seventh month. This is how Qixi came to be. The festival can be traced back to the Han Dynasty (206 BC-AD 220). Traditionally, people would look up at the sky and find a bright star in the constellation Aquila as well as the star Vega, which are identified as Niulang and Zh

37、inu. The two stars shine on opposite sides of the Milky Way. Customs In bygone days, Qixi was not only a special day for lovers, but also for girls. It is also known as the Begging for Skills Festival or Daughters Festival. In this day, girls will throw a sewing needle into a bowl full of water on t

38、he night of Qixi as a test of embroidery skills. If the needle floats on top of the water instead of sinking, it proves the girl is a skilled embroiders. Single women also pray for finding a good husband in the future. And the newly married women pray to become pregnant quickly. Tradition transforme

39、d The love story of Niulang and Zhinu, and the Qixi Festival have been handed down for generations. Yet these ancient traditions and customs are slowly dying out. Many modern Chinese, particularly youngsters, seem to know more about St Valentines Day on February 14, characterized by bouquets of rose

40、s, chocolates and romantic candlelight dinners, than they do about their home-grown day for lovers. Even Qixi is nowadays referred to as the Chinese Valentines Day. More and more young Chinese people begin to celebrate this day in a very similar way as that in western countries. Fewer people than ev

41、er will gaze at the heavens on Saturday to pick out the two stars shining bright on either side of the Milky Way, that is, if people even know on which day Qixi falls. There are ready reminders dotted about, in the form of big ads saying Sales on Chinese Valentines Day! in shops, hotels and restaura

42、nts. But few young women will mark the festival with their boyfriends, or take part in traditional activities to pray for cleverness. A large-scale of exhibition on the Silk Road opened to the public in the National Museum on Thursday. The exhibition displays more than 400 treasures from Shaanxi pro

43、vince, Gansu province and 14 other regions. It is largest scale exhibition that shows the history of the Silk Road in recent years. AsAPECis going on in Beijing, the exhibit aims to show the world this brilliant section of history. The Silk Road is a series of trade and cultural transmission routes

44、that were central to cultural interaction through regions of the Asian continent. It connected the West and East by linking traders, merchants, pilgrims, monks, soldiers, nomads, and urban dwellers from China and India to the Mediterranean Sea during various periods of time. I met my dear hubby in 2

45、009 the second year I was in my school and it was the first year when he came here. We became colleagues. And there was nothing special happening during that year. He was just a kind and humble brother graduated from the same college as me. But we did not know each other till he became my colleague

46、and his office desk was just in front of me. There was only a glass between us. So actually we could see each other when we both look up. But it is not the main reason that really draws us close. How we become close to each other was something seems quite natural. We went out to play badminton with other colleagues and we sometimes cha