水利毕业设计渡槽设计

广东水利电力职业技术学院11届毕业设计渡槽设计渡槽设计专业与班级： 学 生 姓 名： 完 全 学 号： 指导教师姓名： 设计提交日期： 目 录一、基本资料4二、槽身的水力设计41.槽身过水断面尺寸的确定4渡槽纵坡i的确定4槽身净宽B0和净深H0的确定4安全超高52.进出口渐变段的型式和长度计算5渐变段的型式5渐变段长度计算53.水头损失的计算6进口水面降落Z16槽身沿程水头损失7出口水面回升7渡槽总水头损失74.渡槽进出口底部高程的确定7三、槽身的结构设计81.槽身横断面形式82.槽身尺寸的确定83.槽身纵向内力计算及配筋计算9荷载计算9内力计算10配筋计算10底部小梁抗裂验算11底部小梁裂缝宽度验算124.槽身横向内力计算及配筋计算12荷载计算12内力计算12底板配筋计算14底板横向抗裂验算15侧墙配筋计算16侧墙抗裂验算17四、槽架的结构设计181.槽架尺寸拟定182.风荷载计算19作用于槽身的横向风压力19作用于排架的横向风压力193.作用于排架节点上得荷载计算20槽身传递给排架顶部的荷载20作用于排架节点上得横向风压力214.横向风压力作用下的排架内力计算21计算固端弯矩21计算抗变劲度21计算分配系数和查取传递系数22计算杆端弯矩22计算剪力和轴向力225.横杆配筋计算23正截面承载力计算23斜截面承载力计算236.立柱配筋计算24正截面承载力计算24斜截面承载力计算25一、基本资料 某灌溉工程干渠需跨越一个山谷，山谷两岸地形对称。按规划，在山谷处修建钢筋混凝土梁式渡槽。山谷谷底与渠底间最大高差8m，岩石坚硬。渡槽混凝土槽壁表面较光滑（n=0.014），设计流量1m3/s，加大流量1.1m3/s，渡槽长度为80m，每跨长度取为10m，共8跨。渡槽上游渠道为矩形断面，宽1.2m，设计水深h1=0.98m，上游渠底高程25.00m。渡槽下游渠道为矩形断面，宽1.2m，渠道糙率n=0.025，设计水深h2=0.92m。二、槽身的水力设计（一）槽身过水断面尺寸的确定 1.渡槽纵坡i的确定在相同的流量下，纵坡i大，过水断面就小，渡槽造价低；但i大，水头损失大，减少了下游自流灌溉面积，满足不了渠系规划要求，同时由于流速大可能引起出口渠道的冲刷。因此，确定一个适宜的底坡，使其既满足渠系规划允许的水头损失，又能降低工程造价，常常需要试算。一般常采用底坡i=1/5001/1500,槽内的经济流速12m/s。初定取底坡i=1/800。 2.槽身净宽B0和净深H0的确定因L=80m15h1，即按明渠均匀流计算：式中 A槽身的过水断面；R槽身的水力半径n槽身的粗糙系数i槽身纵坡。首先根据通过加大流量槽中为满槽水情况拟定B0和H0值。净深H0净宽B0过水断面A湿周x水力半径R纵坡i流量Qm深宽比h/b0.7600 1.2000 0.9120 2.7200 0.3353 0.00125 1.1116 0.63 0.8000 1.1000 0.8800 2.7000 0.3259 0.001251.0525 0.73 0.8400 1.1000 0.9240 2.7800 0.3324 0.00125 1.1197 0.76 0.8300 1.1000 0.9130 2.7600 0.3308 0.00125 1.1028 0.75 0.8200 1.1000 0.9020 2.7400 0.3292 0.00125 1.0860 0.75 由Qm=1.1m3/s，n=0.014，H0/ B0 =0.75，i=1/800，试算得出B0=1.1m，H0=0.83m。计算所得流量稍大于加大流量，故满足要求。再由B0=1.1m，试算正常水深。净深h0净宽B过水断面A湿周x水力半径R纵坡i流量Qm深宽比h/b0.7000 1.1000 0.7700 2.5000 0.3080 0.00125 0.8869 0.64 0.7500 1.1000 0.8250 2.6000 0.3173 0.001250.9692 0.68 0.7600 1.1000 0.8360 2.6200 0.3191 0.00125 0.9858 0.69 0.7700 1.1000 0.8470 2.6400 0.3208 0.00125 1.0025 0.70 0.7800 1.1000 0.8580 2.6600 0.3226 0.00125 1.0191 0.71 由Qm=1m3/s，n=0.014，H0/ B0=0.70，i=1/800，试算得出h0=0.77m。计算所得流量稍大于设计流量，故满足要求。 3.安全超高 为了防止因风浪或其他原因而引起侧墙顶溢水，侧墙应有一定的超高。按建筑物的级别和过水流量不同，超高可选用0.20.6m。 本渡槽安全超高取=0.2m。（二）进出口渐变段的型式和长度计算 1.渐变段的型式 本渡槽选用圆弧直墙渐变段。 2.渐变段长度计算 渠道与渡槽的过水断面，在形状和尺寸均不相同，为使水流平顺衔接渡槽进出口均需设置渐变段。本渡槽采用圆弧直墙式，渐变段的长度Lj通常采用经验公式计算。 Lj=C（B1 B2）式中 C系数，进口取C=1.542.57；出口取C=2.573.56；B1渠道水面宽度；B2渡槽水面宽度。进口渐变段长度L1=C（B1 B2）=2.0（1.21.1）=0.2m出口渐变段长度L2=C（B1 B2）=3.0（1.21.1）=0.3m进口渐变段长度取L1=0.2m；出口渐变段长度取L2=0.3m。（三）水头损失的计算水流经过渡槽进口段时，随着过水断面减少，流速逐渐加大，水流位能一部分转化为动能，另一部分因水流收缩而产生水头损失，因此进口段将产生水面降落Z1；水流进入槽身后，基本保持均匀流，沿程水头损失Z2=iL；水流经过出口段时，随着过水断面增大，流速逐渐减小，水流动能因扩散而损失一部分，另一部分则转化为动能，而使出口水面回升Z2，从而与下游渠道相衔接（如图所示）。1.进口水面降落Z1进口段水面降落 式中 v1、v分别为上游渠道及渡槽内的平均流速； 进口段局部水头损失系数，与渐变段形式有关。圆弧直墙为0.2，门槽损失系数为0.05。上游渠道流速 v1=Q/A1=1/(1.20.98)=0.850m/s槽内的流速 v=Q/A=1/(1.10.77)=1.1806m/s进口水面降落 =（1+0.25）（）/（29.81）=0.0428m 2.槽身沿程水头损失 Z2=iL式中i、L槽身纵坡和长度。槽身沿程水头损失 =iL=80/800=0.1m 3.出口水面回升式中 v2、v分别为上游渠道及渡槽内的平均流速； 出口段局部水头损失系数，与渐变段形式有关。圆弧直墙为0.5。下游渠道流速V2=Q/A2=1/(1.20.92)=0.9058m/s出口水面回升 =（1-0.5）（）/（29.81）=0.0146m4.渡槽总水头损失=0.028+0.10.0146=0.1134m（四）渡槽进出口底部高程的确定 已知渡槽上游渠道出口断面高程=25.00m，通过设计流量时水深=0.98m,槽中水深h=0.77m，进口渐变段水面降落0.0428m，槽身沿程水面降落=0.1m，出口渐变段水面回升=0.0146m，下游渠道水深。将以上各值代入，可求得：进口槽底高程： =25.00+0.98-0.0428-0.77=25.1672m进口槽底抬高： =25.1672-25=0.1672m出口槽底高程： =25.1672-0.1=25.0672m出口渠底降低： =0.92-0.0146-0.77=0.1354m出口渠底高程： =25.0672-0.1354=24.9318m三、槽身的结构设计（一）槽身横断面形式本渡槽采用矩形断面。（二）槽身尺寸的确定根据前面计算结果，槽内净宽B1.1m，加大水深H=0.83m,安全超高=0.2m，设底板厚0.12m，侧墙厚0.10m，底部小梁高0.10m. 侧墙高H1=0.830.20.12+0.10=1.25m。矩形槽身的侧墙兼做纵梁用，但其薄而高，且需承受侧向水压力作用，因此，设计时除考虑强度外，还考虑了侧向稳定要求。以侧墙厚度t与墙高的比值作为衡量指标，其经验数据为（对于设拉杆的矩形槽）：1/121/16。因本渡槽不设拉杆，侧墙适当加厚，侧墙厚度t取0.10m。贴角45，边长0.10m。槽身基本尺寸（三）槽身纵向内力计算及配筋计算根据设计流量0.7m3/s5 m3/s，工程级别为5级，渡槽的设计标准为5级，所以渡槽的安全级别级，则安全系数为0=0.9，钢筋混凝土重度为=25kN/m3，正常运行期为持久状况，其设计状况系数为=1.0，荷载分项系数为：永久荷载分项系数G=1.05，可变荷载分项系数Q=1.20，结构系数为d=1.2。纵向计算中的荷载一般按匀布荷载考虑，包括槽身重力/槽中水体的重力。1.荷载计算槽身的自重标准值gk1 =252（0.101.25)0.121+2*0.10.1/2=9.5kN/m槽中水体的重力标准值 gk21 =0.8319.81=8.14 kN/m永久标准荷载标准值gk=9.58.14=17.64 kN/m永久标准荷载设计值g=Ggk=1.0517.64=18.52 kN/m 2.内力计算 纵向内力计算简图 梁式渡槽的单跨长L=10m，槽高B=1.1m，则跨宽比L/B=10/1.1=9.094.0故可按梁理论计算，沿渡槽水流方向按简支梁计算应力及内力：结构安全级别为级，则安全系数为0=0.9；正常工作时，设计状况系数=1.0跨中截面弯矩设计值 M=0gl2=0.91.018.52102 =208.35 KNm支座边缘截面剪力设计值V=0gl =0.91.018.5210 =83.34kN 3.配筋计算对于简支梁式槽身的跨中部分底板处于受拉区，故在强度计算中不考虑底板的作用。渡槽处于露天（二类环境条件），则根据规范查得混凝土保护层厚c=25mm，所以受拉钢筋合力点至截面受拉边缘的距离，则截面的有效高度。 d结构系数，d=1.20； fc混凝土轴心抗压强度设计值，混凝土选用C25，则fc=12.5N/mm； b矩形截面宽度； x混凝土受压区计算高度； h0截面有效高度； fy钢筋抗拉强度设计值，取fy=310N/m； As受拉区纵向钢筋截面面积； = 选416 AS=804（mm2）4.底部小梁抗裂验算荷载效应的长期组合，取底部小梁不满足抗裂要求。5. 底部小梁裂缝宽度验算长期荷载组合时，受弯构件，变形钢筋，荷载长期组合，c=25mm有效配筋率按长期组合验算最大裂缝宽度满足要求。（四）槽身横向内力计算及配筋计算 1.荷载计算按沿水流方向与垂直水流方向取单位长度来计算。 永久荷载设计值=永久荷载分项系数rG永久荷载标准值Gk（其中rG1.05）， 沿槽身纵向取1.0m常的脱离体，按平面问题进行横向计算。作用在脱离体上的荷载两侧的剪力差（QQ2Q1）平衡，侧墙与底板交结处可视为铰接。2.内力计算 横向内力计算简图当水深h=0.76m侧墙下部及底板上部最大负弯矩设计值： （r为水的重度）底板跨中正弯矩设计值： 轴向拉力设计值 当水深h为一半计算跨度时，底板跨中最大正弯矩设计值： 3.底板配筋计算渡槽处于露天（二类环境条件），则根据规范查得混凝土保护层厚c=25mm，排两排钢筋，所以受拉钢筋合力点至截面受拉边缘的距离，则截面的有效高度。 d结构系数，d=1.20； fc混凝土轴心抗压强度设计值，混凝土选用C25，则fc=12.5N/mm； b矩形截面宽度； h0截面有效高度； fy钢筋抗拉强度设计值，取fy=310N/m； As受拉区钢筋截面面积；（1）底板上部配筋 = 选受拉钢筋为8150 AS=335（mm2）选分布钢筋6150 AS=188（mm2）在板的常用配筋率0.4%0.8%的范围内，钢筋选定合理。 （2）底板上部配筋底板下部所受到的最大弯矩比上部受到的最大弯矩略小，故配筋与上部相同，选受拉钢筋为8150 AS=335（mm2）选分布钢筋6150 AS=188（mm2）。 4.底板横向抗裂验算荷载效应的长期组合，取底板满足抗裂要求。 5.侧墙配筋计算渡槽处于露天（二类环境条件），则根据规范查得混凝土保护层厚c=25mm，排两排钢筋，所以受拉钢筋合力点至截面受拉边缘的距离，则截面的有效高度。 d结构系数，d=1.20； fc混凝土轴心抗压强度设计值，混凝土选用C25，则fc=12.5N/mm； b矩形截面宽度； h0截面有效高度； fy钢筋抗拉强度设计值，取fy=310N/m； As受拉区钢筋截面面积； = 选受拉钢筋为8150 AS=335（mm2）选分布钢筋6150 AS=188（mm2） 在板的常用配筋率0.4%0.8%的范围内，钢筋选定合理。6.侧墙抗裂验算荷载效应的长期组合，取侧墙满足抗裂要求。 槽身剖面图四、槽架的结构设计（一）槽架尺寸拟定 排架及板基结构布置图单排架两立柱中心距取决于槽身的宽度，由槽身传过来的荷载P应与柱中心线一致，以使立柱为中心受压构件。立柱断面尺寸：长边（顺槽向）为排架总高的（1/201/30），所以取为（0.270.4m），取0.4m；短边（横槽向）=（0.50.8），所以取为（0.20.32m），取0.25m。取立柱间距为1.35m，净距为1.1m.排架立柱间设横梁，横梁间距可等于或略大于立柱间距。横梁高可为跨度（即立柱间距）的1/61/8，取0.3m，梁宽为（0.50.7），所以取为（0.150.21），取0.2m。横梁与立柱连接处设承托，以改善交角处的应力状况，承托高10cm，其中布置斜筋。为支承槽身，排架顶部在顺水流方向设短悬臂梁式牛腿，悬臂长度，高度h=0.2，倾角（二）风荷载计算1.作用于槽身的横向风压力作用于槽身的风荷载强度按下式计算： 式中：；为风载体形系数，对于矩形槽身高宽比为1，取=1.97；为风压高度变化系数，因槽身迎风面形心距地面高度约为8m，近似取=0.92；为地形、地理条件系数，去=1；为风振系数，由于渡槽高度不大，可不计风振影响，取=1。作用于槽身的风荷载强度为：已知槽身高度1.18m，一节槽身长10m，则作用于槽身上得横向风压力为：2.作用于排架的横向风压力考虑前柱对后柱的挡风作用，排架的风荷载强度按下式计算： 。式中：风载体形系数取1.3；风压高度变化系数按排架迎风面积形心距地面高度（约4m）选取，近似取=0.8；及的取值与槽身相同。的大小与两立柱净距和立柱迎风面宽度之比1.1/0.4=2.7510，值在0.21.0之间变化。从安全角度出发，不考虑前柱对后柱的挡风作用，取=1。作用于排架的风荷载强度为：（三）作用于排架节点上得荷载计算1.槽身传递给排架顶部的荷载作用于槽身的横向风压力通过支座的摩阻作用，以水平力形式传到排架顶部；同时，距排架顶高度1.25/2+0.1=0.725m(支座高度0.1m),对排架顶高程所产生的力矩将转化为一对方向相反的集中力，分别作用于两立柱顶部，迎风面力的方向向上背风面力的方向向下。槽身自重及槽中水重也通过支座传到排架顶部。 一跨槽身自重满槽水重 1）满槽水+横向风压力情况 2）空槽+横向风压力情况 62.作用于排架节点上得横向风压力（即与结点相邻的上半柱与下半柱的横向风压力之和）（四）横向风压力作用下的排架内力计算排架的内力可以分解为竖向荷载作用及横向荷载作用两种情况进行计算，然后再叠加。竖向荷载作用下，只在排架立柱中产生轴向力。横向风压力作用下的内力，可采用“无切力分配法”按下述步骤计算。1.计算固端弯矩（下述计算中，弯矩以顺时针为正）2.计算抗变劲度对于立柱 对于横梁 取相对劲度 则横梁各杆端的相对劲度为3.计算分配系数和由结构力学书中查取传递系数4.计算杆端弯矩计算过程见下表。杆端弯矩（Knm）计算表结点123杆端111221222332相对劲度分配系数5.0790.83510.16510.1415.0790.71710.141传递系数-1-1-1固端弯矩-8.79-8.79-9.36-9.36分配与传递7.3402.3080.0221.450-2.7640.456-0.0260.004-1.4502.764-0.4560.064-0.0040.00114.0530.3270.0022.7640.0640.001-2.764-0.064-0.0019.67-9.67-7.87114.382-6.531-12.1895.计算剪力和轴向力由上表的计算成果中横杆的杆端弯矩为： 取各横杆为脱离体，根据力矩平衡条件，可得各横杆的剪力为：按以上方法，即可求得横向荷载P和Q作用下左半部分排架各个位置的内力。右半部分排架各相应位置的内力，可以根据反对称关系求得。（五）横杆配筋计算 1.正截面承载力计算 横杆弯矩较大，按进行配筋计算。 d结构系数，d=1.20； fc混凝土轴心抗压强度设计值，混凝土选用C25，则fc=12.5N/mm； b矩形截面宽度； h0截面有效高度； fy钢筋抗拉强度设计值，取fy=310N/m； As受拉区钢筋截面面积； 受压区钢筋截面面积； 保护层厚度。设受压、受拉钢筋为一层；取 ,则选受拉钢筋为310（AS=236mm2），选受压钢筋为28 （AS=101mm2） 2.斜截面承载力计算1）截面尺寸复核 故截面尺寸满足抗剪要求。2）验算是否需要按计算配置腹筋 故不需按计算配置箍筋。 按构造要求配置箍筋，选用双肢箍筋， 故所选箍筋满足要求。 横梁剖面（六）立柱配筋计算 1.正截面承载力计算立柱采用对称配筋1）判别偏心受压类型 属大偏心受压构件。2)配筋计算 x=23.63mm ,取选用310（） 2.斜截面承载力计算 1)截面尺寸复核 故截面尺寸满足抗剪要求。2) 验算立柱是否需要按计算配置腹筋立柱承受均布荷载，=1.4，轴向压力对抗剪有利，故取空槽时N=37.47kN 故不需按计算配置箍筋。按构造要求配置箍筋，选用双肢箍筋， 故所选箍筋满足要求。 立柱剖面g an employment tribunal claimEmployment tribunals sort out disagreements between employers and employees.You may need to make a claim to an employment tribunal if: you dont agree with the disciplinary action your employer has taken against you your employer dismisses you and you think that you have been dismissed unfairly.For more information about dismissal and unfair dismissal, seeDismissal.You can make a claim to an employment tribunal, even if you haventappealedagainst the disciplinary action your employer has taken against you. However, if you win your case, the tribunal may reduce any compensation awarded to you as a result of your failure to appeal.Remember that in most cases you must make an application to an employment tribunal within three months of the date when the event you are complaining about happened. If your application is received after this time limit, the tribunal will not usually accept it.If you are worried about how the time limits apply to you, take advice from one of the organisations listed underFurther help.Employment tribunals are less formal than some other courts, but it is still a legal process and you will need to give evidence under an oath or affirmation.Most people find making a claim to an employment tribunal challenging. If you are thinking about making a claim to an employment tribunal, you should get help straight away from one of the organisations listed underFurther help.If you are being represented by a solicitor at the tribunal, they may ask you to sign an agreement where you pay their fee out of your compensation if you win the case. This is known as adamages-based agreement. In England and Wales, your solicitor cant charge you more than 35% of your compensation if you win the case.If you are thinking about signing up for a damages-based agreement, you should make sure youre clear about the terms of the agreement. It might be best to get advice from an experienced adviser, for example, at a Citizens Advice Bureau. To find your nearest CAB, including those that give advice by e-mail, click onnearest CAB.For more information about making a claim to an employment tribunal, seeEmployment tribunals.The (lack of) air up there Watch mCayman Islands-based Webb, the head of Fifas anti-racism taskforce, is in London for the Football Associations 150th anniversary celebrations and will attend Citys Premier League match at Chelsea on Sunday.I am going to be at the match tomorrow and I have asked to meet Yaya Toure, he told BBC Sport.For me its about how he felt and I would like to speak to him first to find out what his experience was.Uefa hasopened disciplinary proceedings against CSKAfor the racist behaviour of their fans duringCitys 2-1 win.Michel Platini, president of European footballs governing body, has also ordered an immediate investigation into the referees actions.CSKA said they were surprised and disappointed by Toures complaint. In a statement the Russian side added: We found no racist insults from fans of CSKA.Age has reached the end of the beginning of a word. May be guilty in his seems to passing a lot of different life became the appearance of the same day; May be back in the past, to oneself the paranoid weird belief disillusionment, these days, my mind has been very messy, in my mind constantly. Always feel oneself should go to do something, or write something. Twenty years of life trajectory deeply shallow, suddenly feel something, do it.一字开头的年龄已经到了尾声。或许是愧疚于自己似乎把转瞬即逝的很多个不同的日子过成了同一天的样子；或许是追溯过去，对自己那些近乎偏执的怪异信念的醒悟，这些天以来，思绪一直很凌乱，在脑海中不断纠缠。总觉得自己自己似乎应该去做点什么，或者写点什么。二十年的人生轨迹深深浅浅，突然就感觉到有些事情，非做不可了。The end of our life, and can meet many things really do?而穷尽我们的一生，又能遇到多少事情是真正地非做不可？During my childhood, think lucky money and new clothes are necessary for New Year, but as the advance of the age, will be more and more found that those things are optional; Junior high school, thought to have a crush on just means that the real growth, but over the past three years later, his writing of alumni in peace, suddenly found that isnt really grow up, it seems is not so important; Then in high school, think dont want to give vent to out your inner voice can be in the high school children of the feelings in a period, but was eventually infarction when graduation party in the throat, later again stood on the pitch he has sweat profusely, looked at his thrown a basketball hoops, suddenly found himself has already cant remember his appearance.童年时，觉得压岁钱和新衣服是过年必备，但是随着年龄的推进，会越来越发现，那些东西根本就可有可无；初中时，以为要有一场暗恋才意味着真正的成长，但三年过去后，自己心平气和的写同学录的时候，突然就发现是不是真正的成长了，好像并没有那么重要了；然后到了高中，觉得非要吐露出自己的心声才能为高中生涯里的懵懂情愫划上一个句点，但毕业晚会的时候最终还是被梗塞在了咽喉，后来再次站在他曾经挥汗如雨的球场，看着他投过篮球的球框时，突然间发现自己已经想不起他的容颜。Originally, this world, can produce a chemical reaction to an event, in addition to resolutely, have to do, and time.原来，这个世界上，对某个事件能产生化学反应的，除了非做不可的坚决，还有，时间。A persons time, your ideas are always special to clear. Want, want, line is clear, as if nothing could shake his. Also once seemed to be determined to do something, but more often is he backed out at last. Dislike his cowardice, finally found that there are a lot of love, there are a lot of miss, like shadow really have been doomed. Those who do, just green years oneself give oneself an arm injection, or is a self-righteous spiritual.一个人的时候，自己的想法总是特别地清晰。想要的，不想要的，界限明确，好像没有什么可以撼动自己。也曾经好像已经下定了决心去做某件事，但更多的时候是最后又打起了退堂鼓。嫌恶过自己的怯懦，最终却发现有很多缘分，有很多错过，好像冥冥之中真的已经注定。那些曾经所谓的非做不可，只是青葱年华里自己给自己注射的一支强心剂，或者说，是自以为是的精神寄托罢了。At the moment, the sky is dark, the air is fresh factor after just rained. Suddenly thought of blue plaid shirt; Those were broken into various shapes of stationery; From the corner at the beginning of deep friendship; Have declared the end of the encounter that havent start planning. Those years, those days of do, finally, like youth, will end in our life.此刻，天空是阴暗的，空气里有着刚下过雨之后的清新因子。突然想到那件蓝格子衬衫；那些被折成各种各样形状的信纸；那段从街角深巷伊始的友谊；还有那场还没有开始就宣告了终结的邂逅计划那些年那些天的非做不可，终于和青春一样，都将在我们的人生中谢幕。Baumgartner the disappointing news: Mission aborted. r plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.The supersonic descent could happen as early as Sunda.The weatheThe balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, hell be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end. Skydiver preps for the big jumpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes its not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everythin