道路工程毕业设计计算书

_摘 要根据设计任务书提供的设计资料和设计要求以及交通部颁发的标准和规范对怀化至通道高速公路K176+500-K178+500段提供了路基路面综合设计。此次设计主要内容包括：路线设计、路基、路面设计，英文翻译，计算机程序编制。根据提供的路线原始资料，考虑土石方填挖平衡、最大纵坡、最小纵坡、坡长、高程控制点等因素进行纵断面设计,由此结合平面图进行横断面设计。根据设计段内的地形状况，设置了边沟、截水沟、排水沟、圆管涵等排水设施。同时，进行挡土墙设计计算和防护工程设计,设置挡土墙，采用植草皮等形式进行边坡防护。高填路堤路段采用修筑挡土墙的方法收缩坡脚，减少填方，增加路堤边坡稳定性；用毕肖普法进行了边坡稳定性验算。设计进行了沥青混凝土路面的设计和水泥混凝土路面的设计，由给定的交通量等条件，按照路面结构组合设计的原则，选用不同路面结构层厚度和材料进行结构设计验算。通过本次毕业设计，在专业知识方面得到了综合训练和提高，增强了独立分析问题和解决问题的能力。关键词：高速公路、路基设计、路面设计、综合设计ABSTRACTAccording to the design information, demands of the design task instrument, the technical standards and specifications for highway design published by the Ministry of Communications of China, the comprehensive design of highway subgrade and pavement from K178+500 to K178+500 has been carried out based on the data of HuaihuaTongdao expressway in HuNan province.Our prime contents of the design project includes highway vertical alignment, the design of pavement, translating an English article into Chinese, and compile a simple computer programme. According to route firsthand information that is offered ,we must onsider the balance between the diging of filling out,heavy vertical slope, minimum vertical slope, the longth of slope, high control point,etc. During designing the vertical section, and combine the plane figure and design the cross section. According to the condition of climate district and remitting calculation water of quantity, set up side ditch, intercepting ditch, round culverts, cover pulls culverts etc. Meanwhile, do block design of wall of soil calculate and protect engineering design , set up the retaining wall to go on, adopt plant turf to protect the slope ,etc. In high embankment highway section, shrink slope foot by building the retaining wall, reduce the filling, increase the slope stability; make use of BISHOP to follow the checking stability calculation. Do the design which has carried on the pitch concrete road surface and design of the cement concrete road surface by giving volume of traffic definitely terms, according to the design principle of the road surface structure, select for different road surface structure layers of thickness and material then carry on structural design checking computations.Through the graduation project, the specialized knowledge has been comprehensively applied and improved and the ability to analyse and solve problems on our own hai been enhanced.Keyword：expressway; roadbed design; pavement design; integrated design；83_目录第一章 线形设计1.1平曲线的计算1.1.1平曲线要素的计算已知： JD4 圆曲线半径R=1000m，转角=425305.3(右)；曲线总长；Ls=250m。计算： 0=28.6479Ls/R=7.162，q=Ls/2=125m，p=Ls/24R=2.604m，外距；曲线总长Lh=(-20)R/180+2Ls=998.481切线长；T=(R+p)tg/2+q=518.707切曲差。1.1.2各主点桩号的计算已知： JD1桩号为： K177+865.720；计算：直缓点桩号为ZY=JD-T= K177+846.253；缓圆点桩号为HY=ZH+LS1= K177+347.013曲中点桩号为QZ=ZY+L总/ 2= K177+846.253；圆缓点桩号为HY=ZH+LS1= K178+095.494圆直点桩号为YZ=ZY+Ls= K178+345.494。1.1.3 逐桩坐标表桩 号坐 标桩 号坐 标N (X)E (Y)N (X)E (Y)K176+5002886015.968495782.0482K177+0002885519.923495844.8127K176+5202885996.127495784.5588K177+0202885500.082495847.3233K176+5402885976.285495787.0694K177+0402885480.24495849.8339K176+5602885956.443495789.5799K177+0602885460.398495852.3444K176+5802885936.601495792.0905K177+0802885440.556495854.855K176+6002885916.759495794.6011K177+1002885420.714495857.3656K176+6202885896.918495797.1117K177+1202885400.873495859.8762K176+6402885877.076495799.6223K177+1402885381.031495862.3868K176+6602885857.234495802.1328K177+1602885361.189495864.8973K176+6802885837.392495804.6434K177+1802885341.347495867.4079K176+7002885817.55495807.154K177+2002885321.505495869.9185K176+7202885797.709495809.6646K177+2202885301.664495872.4291K176+7402885777.867495812.1752K177+2402885281.822495874.9397K176+7602885758.025495814.6857K177+2602885261.98495877.4502K176+7802885738.183495817.1963K177+2802885242.138495879.9608K176+8002885718.341495819.7069K177+3002885222.296495882.4714K176+8202885698.5495822.2175K177+3202885202.455495884.982K176+8402885678.658495824.7281K177+3402885182.613495887.4926K176+8602885658.816495827.2386K177+347.032885175.655495888.3729K176+8802885638.974495829.7492K177+3602885162.771495890.0017K176+9002885619.132495832.2598K177+3802885142.926495892.49K176+9202885599.291495834.7704K177+4002885123.075495894.9259K176+9402885579.449495837.281K177+4202885103.214495897.2776K176+9602885559.607495839.7915K177+4402885083.339495899.5133K176+9802885539.765495842.3021K177+4602885063.449495901.6012桩 号坐 标桩 号坐 标N (X)E (Y)N (X)E (Y)K177+4802885043.54495903.5091K177+9602884571.59495844.5295K177+5002885023.612495905.2051K177+9802884552.959495837.2577K177+5202885003.665495906.6571K178+0002884534.477495829.6147K177+5402884983.7495907.833K178+0202884516.152495821.6037K177+5602884963.719495908.7004K178+0402884497.991495813.2278K177+5802884943.726495909.2273K178+0602884480.001495804.4904K177+597.012884926.714495909.3834K178+0802884462.189495795.3949K177+6002884923.727495909.3815K178+095.492884448.518495788.1049K177+6202884903.729495909.139K178+1002884444.563495785.9451K177+6402884883.739495908.4966K178+1202884427.124495776.1531K177+6602884863.767495907.4545K178+1402884409.865495766.0481K177+6802884843.819495906.0133K178+1602884392.774495755.6607K177+7002884823.904495904.1734K178+1802884375.839495745.0209K177+7202884804.03495901.9356K178+2002884359.047495734.1578K177+7402884784.205495899.3008K178+2202884342.382495723.0999K177+7602884764.436495896.2701K178+2402884325.829495711.8753K177+7802884744.732495892.8446K178+2602884309.371495700.5113K177+8002884725.1495889.0257K178+2802884292.991495689.0351K177+8202884705.549495884.815K178+3002884276.672495677.4731K177+8402884686.086495880.2142K178+3202884260.395495665.8519K177+8602884666.718495875.225K178+3402884244.141495654.1975K177+8802884647.455495869.8495K178+345.492884239.678495650.9938K177+9002884628.302495864.0898K178+3602884227.893495642.536K177+9202884609.269495857.9482K178+3802884211.63495630.8943K177+9402884590.362495851.4273K178+4002884195.334495619.29971.2竖曲线的计算 1.2.1 竖曲线要素的计算已知：第1变坡点：K175+996.079，高程：452.3568m， 竖曲线半径R=21000m，i= 2.209%， i= -0.748%，为凹形曲线；第2变坡点：K176+980，高程：445m，竖曲线半径R=10000m，i=-0.748%，i=2.166%，为凸形曲线；第3变坡点：K177+857.213，高程：464m，竖曲线半径R=30000m，i=2.166%， i=-0.623%，为凸形曲线；计算得： 竖曲线一：，为凸形曲线，曲线长；切线长；外距。竖曲线二： 同理求得：曲线长切线长L=291.366m；T=145.683m，外距E= 1.061m。竖曲线三： 同理求得：曲线长切线长L3=836.472m；T3= 418.236m，外距E3= 2.915m。1.2.2 竖曲线要点桩号及高程的计算竖曲线一： 起点桩号= K175+685.575T=K175+685.575；终点桩号= K175+685.575T=K175+996.079；变坡点对应桩号设计高程=450.061；竖曲线一起点设计高程=442.364m；竖曲线一终点设计高程=448.973m。竖曲线二： 起点桩号= K176+834.317；终点桩号=K177+125.683；变坡点二对应桩号设计高程=445+E=456.062m；竖曲线二起点设计高程=441.671；竖曲线二终点设计高程=454.639m。竖曲线 三： 起点桩号= K177+438.977；终点桩号=K178+275.449；变坡点三对应桩号设计高程=461.085m；竖曲线三起点设计高程=453.950m；竖曲线三终点设计高程=460m。第二章 路堤边坡稳定性分析2.1 边坡资料：本路段中填方路堤K177+960横断面为最高路堤，所以路堤边坡稳定性验算采用此断面为验算对象。此横断面高19.03m，路基宽度24.5米，边坡坡度采用1：1.5 和1：1.75，路堤填土为粘性土，根据公路路基设计手册取土粘聚力，填土容重，内摩擦角为35，根据公路工程技术标准(JTGB012003)，高速公路的汽车荷载等级为公路级，其分析过程如下： 2.1.1. 把汽车荷载换算成土柱高(当量高度)。按公式换算土柱高度为公式中：L纵向分布长度(等于汽车后轴轮胎的总距)，L=12.8m B横向分布车辆轮胎最外缘间总距。B = Nb + (N -1)m + d其中：N为车辆数为3；m为两辆车后轮的中心距离，取1.3m；b为后轮轮距，为1.8m；d为轮胎的着地宽度，取0.6，则：B=12.8m故h0=0.8238mH = 19.03 其中h0为荷载的换算高度，H 为荷载均匀分布于路基时路堤坡脚至荷载顶面的高度。2.1.2确定滑动圆心辅助线EF。用4.5H 法确定滑动圆心的辅助线。边坡坡度为30由路基设计手册表1-2-14 得126， 235据此作AF、BF 线交于F 点；再在坡脚下H 处的C 点及沿水平线4.5H 处得E 点，连EF 线得最危险滑弧圆心位置的辅助线，见图2-1 图2-1 4.5H 法确定滑动圆心辅助线示意图2.1.3 用简化毕绍普法求稳定系数Fs通过计算选中的五个圆心点对应的安全系数Ki，得到最小值K 和对应的圆心点，再进行验算。计算Ki 时，采用简化bishop 法，并假设滑动面通过坡脚。简化bishop 法需要迭代，先假设一个K 值进行反复带入计算(具体迭代过程见表)。简化毕肖普法的计算公式如下：式中： K安全系数；W i 各土条重，KN；c填土的粘聚力，KPa；b i 各土条宽度，m；h i 各土条高度，包括堤顶车辆荷载的换算土柱高度。用迭代法求解安全系数K计算步骤为：先假定一个K1 值，代入公式的右边，计算出K2；再将K2 代入公式的右边，计算出K3 ，如此反复迭代，直至Kn+1K n为止；2.2 计算分析其计算过程为：(1)在圆心辅助线上取圆心点O1，作半径为R1=42.35m 的圆弧滑动面，对滑动面范围内的土体按断面形式将滑动面分为10个土条，如图2-2验算其稳定性，计算结果见表2-1图 2-2 圆心为O1时的滑动面(2)在滑动圆弧圆心辅助线上取同一圆心点O2，作半径为R2=39.84m 的圆弧滑动面，按断面形式将滑动面分为10 个土条，如图2-3 验算其稳定性，计算结果见表2-2。图2-3 圆心为O2 的滑动面示意图(3)在滑动圆弧圆心辅助线上取同一圆心点O3，作半径为R3=38.01m 的圆弧滑动面，按断面形式将滑动面分为11个土条，如图2-4 验算其稳定性，计算结果见表2-3。图2-4 圆心为O2 的滑动面示意图(4)在滑动圆弧圆心辅助线上取同一圆心点O4，作半径为R4=36.7m 的圆弧滑动面，按断面形式将滑动面分为10 个土条，如图2-5 验算其稳定性，计算结果见表2-4。 综合上述分析，得出K 值曲线图如下。通过比较，过坡角的六个滑动面中Fs 最小的是过圆心O3 画的弧所得滑动面，Fs(min)= Fs3=1.402。所以，最不利滑动面圆心为O3；滑动半径R3= 40.01m。滑动安全系数Fs3= 1.402Fs=1.25，所以验算的K177+960m 处的边坡处于稳定状态。土条号LisinacosaFi()Qi(KN)QitanQisinaCiLicosa m Ki14.6732.530.817 0.577 7.359 129.809 60.530 106.005 39.622 0.577 173.443 24.1530.20.747 0.665 16.714 294.826 137.477 220.139 40.580 0.905 196.681 36.4126.580.667 0.745 38.643 681.663 317.859 454.714 70.199 0.960 404.430 44.8322.260.559 0.829 35.027 617.876 288.116 345.315 58.878 1.009 343.906 54.518.290.459 0.888 33.902 598.031 278.862 274.546 58.767 1.036 325.888 64.2914.270.358 0.934 33.922 598.384 279.026 214.295 58.880 1.049 322.171 74.1410.270.259 0.966 30.702 541.583 252.540 140.446 58.776 1.049 296.722 84.056.350.159 0.987 24.972 440.506 205.408 70.246 58.773 1.038 254.391 94.012.420.061 0.998 17.534 309.300 144.226 18.801 58.838 1.018 199.533 105.33-1.54-0.039 0.999 8.916 157.278 73.339 -6.070 78.293 0.987 153.653 1838.438 2670.819 K1.453 表2-1土条号LisinacosaFi()Qi(KN)QitanQisinaCiLicosamKi14.6732.530.8170.5777.359129.80960.530106.00539.6220.577173.44324.1530.20.7470.66516.714294.826137.477220.13940.5800.905196.68136.4126.580.6670.74538.643681.663317.859454.71470.1990.960404.43044.8322.260.5590.82935.027617.876288.116345.31558.8781.009343.90654.518.290.4590.88833.902598.031278.862274.54658.7671.036325.88864.2914.270.3580.93433.922598.384279.026214.29558.8801.049322.17174.1410.270.2590.96630.702541.583252.540140.44658.7761.049296.72284.056.350.1590.98724.972440.506205.40870.24658.7731.038254.39194.012.420.0610.99817.534309.300144.22618.80158.8381.018199.533105.33-1.54-0.0390.9998.916157.27873.339-6.07078.2930.987153.6531838.4382670.819K1.453表2-2表2-3土条号LiasinacosaFi()Qi(KN)QitanQisinaCiLicosamKi14.9631.770.8360.5497.791137.42464.081114.89340.0040.818127.31824.1929.450.7750.63217.802314.018146.427243.29138.9420.881210.31233.7226.880.7070.70725.756454.327211.853321.29738.6630.934268.09046.0223.230.6110.79152.520926.444432.001566.27770.0380.988508.13054.6118.890.4970.86844.689788.310367.589391.86558.8011.028414.95664.3514.910.3920.92042.024741.298345.667290.85158.8181.046386.70074.1810.890.2870.95840.710718.124334.861205.83258.8681.050374.90384.076.940.1830.98336.060636.098296.613116.14958.8231.042341.13991.012.980.0850.99629.061512.636239.04243.78814.7931.024247.931104.01-0.96-0.0251.00020.270357.563166.732-9.04258.9280.992227.583115.38-4.92-0.1290.99210.270181.16384.476-23.43078.4220.950171.4702261.7723278.532K1.44954表2-4土条号LisinacosaFi()Qi(KN)QitanQisinaCiLicosamKi15.3131.380.8550.5198.365147.55068.802126.13440.5010.773141.47524.3429.050.7920.61119.091336.756157.030266.58338.9820.846231.69733.8126.480.7220.69227.445484.121225.746349.31438.7780.907291.79543.4623.880.6510.75933.551591.831275.971385.10138.6220.952330.28955.720.230.5510.83465.6661158.348540.138638.50969.9110.998611.28964.4415.880.4330.90253.937951.449443.661411.64658.8431.030487.87775.7711.150.3090.95167.6001192.459556.043367.87680.6821.043610.59685.575.70.1540.98860.7911072.353500.038164.79580.9061.034561.986950.50.0141.00042.377747.530348.57310.09873.4931.004420.419104.03-3.98-0.1080.99422.918404.274188.513-43.85858.8910.962257.204115.48-7.94-0.2160.97611.596204.54895.381-44.27678.6460.912190.8102631.9234135.438K1.57126第三章 挡土墙设计3.1 设计资料挡土墙是支撑路基填土或山坡土体，防止填土或土体变形失稳的构造物。为了收缩边坡坡脚，防止陡坡路堤下滑，设置路堤挡土墙，同时也避免与其它建筑干扰或者多占农田。设计验算挡土墙时需要计算其所受土压力，一般为主动土压力。而库伦理论本来只考虑不具有粘聚力的砂性土的土压力问题。当墙后填料为粘性土时，土的粘聚力对主动土压力的影响很大，因此应考虑粘聚力的影响。采用等效内摩擦角：通常将内摩擦角和单位粘聚力c，换算成比值大的等效内摩擦角D，按砂性土的公式来计算土压力。但是影响土压力数值的因素是多方面的，不能用上述方法确定一个固定的换算关系或固定的换算值。用上述方法换算的内摩擦角，只与某一特定的墙高相适应，对于矮墙偏于安全，对于高墙则偏于危险。 3.1.1墙身构造本设计任务段中K178+100K178+220的左侧设置了俯斜式路堤挡土墙，以收缩坡脚，减少占地，减少填方量，增强路基的稳定性，现取K178+180截面的左侧进行挡墙设计计算，其断面尺寸如图3-1所示：拟采用浆砌片石俯斜式路堤墙，墙高H=9.4米，墙顶填土高a =3m，顶宽2.8米，底水平宽5米，墙背府斜，坡度为1：0.2故(a=arctan (0.2/1)=11.94)，墙面垂直，基底倾斜，坡度为1：5故(a0=arctan(0.2)= 11.31)，路基边坡角=33.69故b=4.5m。设计荷载公路I级。由于经典库伦理论只考虑不具有粘聚力的砂性土的土压力问题。因此计算粘性土土压力时采用等效内摩擦角法，取其等效内摩擦角进行计算。3.1.2土壤地质情况填土为粘性土，土的粘聚力C=25KPa，其等效内摩擦角=35，墙背与填土间的摩擦角=/2= 17.5，容重为=18kN m3。粘性土地基容许承载力350Kpa，基底摩擦系数取0.4。3.1.3墙身材料采用7.5 号砂浆，25 号片石，砌体容重为k =23KN/ m 3 查规范得砌体容许压应力为600KPa，容许剪应力为100KPa，容许拉应力为60KPa。3.1.4车辆荷载换算根据公路路基设计规范(JTG D30-2004)，为计算的方便车辆荷载，可简化换算为路基填土的均布土层，并采用全断面布载。换算土层厚：(10-2)/(20-10)=(10-8)/(q -10)解得：q=11.667h 0 = q/=11.667/18=0.648m式中，q为附加荷载强度，为墙后填土容重=18kN/ m33.2 墙背土压力计算对于墙趾前土体的被动土压力Ep，在挡土墙基础一般埋深的情况下，考虑到各种自然力和人畜活动的作用，以偏于安全，一般均不计被动土压力，只计算主动土压力。3.2.1 破裂面计算假设破裂面交于荷载中部，则：A0=1/2(a+H+2h0)(a+H)=1/2(3+9.4+20.648)(3+9.4)=84.915B0=1/2ab+(b+d)h0-1/2H(H+2a+2h0)tana=1/234.5+(4.5+0.75)0.648-1/29.4(9.4+23+20.648)tan11.97=-6.485=0.54其中=40.56破裂角=28.183.2.2 验算破裂面是否交于荷载内堤顶至墙踵的距离：(H+a)tan=(9.7+3) 0.54=6.7m荷载内缘至墙踵的距离：-Htan a+b+d=-9.40.2+4.5+0.75=3.37荷载外缘至墙踵的距离：-Htan a+b+d+ l0 =-9.40.2+4.5+0.75+11.5=14.87 3.376.714.87 假设满足要求。3.2.3 主动土压力计算Ea=(A0tan- B0)cos(+)/sin(+)=18(84.9150.54+6.485)cos63.18/sin63.18=476.304KN=476.304cos(11.31+17.5)=417.348KN=476.304sin(11.31+17.5)=229.534KN3.2.4 主动土作用点位置确定h1=d/(tan+ tan a)=0.75/(0.54+0.20)=1.014mh2=(b-atan)/(tan+ tan a)=(4.5-30.54)/(0.54+0.20)=3.892mh3=H- h1- h2=9.4+1.014-3.892=6.522mZ y =H +a(H -3h1H+ h2)+3 h0h3/3(H +2aH-ah1-2 h0h3)=9.4 +3(9.4 -31.0149.4+3.892 )+30.6486.522 /3(9.4+239.4-31.014-20.6486.522)=2.846mZ x=B- Z ytan a=5-2.8460.2=4.43m3.3 墙身截面性质计算3.3.1 截面面积A1=26.47m A2=9.37m A3=2.36m A=A1+A2+A3=38.1m 3.3.2 各截面重心到墙趾的水平距离X1=1.4mX2=3.46mX3=3.26m 墙身重心到墙趾的水平距离为=(26.471+9.373.46 +2.363.26)/38.1=1.607m墙身重力：G=k Ai=2338.1=876.3KN3.4 墙身稳定性验算(分项安全系数法)3.4.1 抗滑动稳定性验算验算采用“极限状态分项系数法”。滑动稳定方程：0.9G+Q1(Ey+Extan0)+(0.9G+Q1Ey)tan0-Q1Ex=0.9876.3+1.4(229.534+417.3480.25) 0.4+(0.9876.3+1.4229.534) 0.251.4417.348+0.50=195.6530抗滑稳定性系数：N=(GG+Q1Ey-W)cos a0+Q1Exsin a0=(876.31.2+1.4229.534-0)cos11.31+1.4417.348sin11.31 =1460.835KNKc=1460.835+(417.348-0) 0.2 0.39+0/(417.3481460.8350.2)=4.811Kc=1.3 所以抗滑稳定性满足要求。3.4.2 抗倾覆稳定性验算：验算采用“极限状态分项系数法”。倾覆稳定方程：0.8GZG+Q1(EyZx-ExZy)+ Q2EpZp0=0.8876.31.607+1.4(229.5344.43-417.3482.846)+ 0=859.3030 =(876.31.607+229.5344.43)/(417.3482.846) =2.042K0=1.5 所以抗倾覆稳定性满足要求3.4.3 基底应力及合力偏心距验算为了保证挡土墙基底应力不超过地基承载力，应进行基底应力验算；同时，为了避免挡土墙不均匀沉陷，控制作用于挡土墙基底的合力偏心距。(1) 轴心荷载作用时：p=N/AN1=(GG+Q1Ey-W)cos a0+Q1Exsin a0 =(876.31.2+1.4229.534-0)cos11.31+1.4417.348sin11.31 =1460.835KN所以：p=N/A=1460.835/(5.11)=286.438KPa350Kpa式中：A=B1(B为倾斜基底宽度：B=5.0/cos1118=5.1m，P为基地平均压应力，N1为每延米作用于基地的总竖向设计值(KN)故基础地面压应力满足要求。(2)偏心荷载作用时：作用于基底的合力偏心距 e0=0.05| e0|=0.05B/6= 0.85 M=G(Zg-B/2)+Ey(Zx-B/2)-ExZy= -876.3(1.607-5.1/2)+ 229.534 (4.43 -5.1/2)- 417.3482.846=70.102kNmN1=(GrG+ rQ1Ey)cos0+rQ1Exsin0=1460.835 (N)则： Pmax=303.288KPa)0=350(KPa) Pmin=269.585(KPa)0=350(KPa)其中A=B1.0=5.11=5.1m2故偏心距与基底应力均满足要求。3.4.4 地基承载力抗力值验算当挡土墙的基础宽度大于3m，或埋置深度大于0.5m时，除岩石地基外，地基承载应力抗力值按下式计算： =350+0.318(5.1-3)+1.618(1.5 -0.5)=390.14KPa式中：f地基承载应力抗力值； fk地基承载应力标准值； 取0.3，取1.6(1) 轴心荷载作用时，P =286.438 KPa390.14KPa(2) 当偏心荷载作用时，Pmax=303.288KPa390.14KPa故地基承载力抗力值符合要求。3.4.5 墙身截面强度计算查公路路基设计规范(JTG D30-2004)表5.4.4-1，抗力分项系数k=2.31 K=0.998，为轴向力偏心影响系数。2205.58Nj=0(GNG+Q1NQ1+QiCiNQi)=1.05(1.2417.438+1.4229.534+0) =863.387KN2205.58KN故墙身强度满足要求。稳定计算，要求： 。查公路路基设计规范(JTG D30-2004)表5.4.4-3，与材料有关的系数 s=0.002S=(29.4)/5.1=3.686K =11+0.0023.386(3.386-3)1+16(0.05/5.1) =0.996 0 Nd= 2196.452KN故稳定性满足要求。3.4.6 正截面直接受剪验算要求：其中， =Ex=417.348KNAjRj/=(4.4390) 2.31+0.421460.835=786.148KNQj式中： Qj正截面剪力(KN) Aj受剪截面面积(m) Rj砌体截面的抗剪截面强度(kpa) fm摩擦系数，fm=0.42。故：抗剪满足要求。综上分析计算，所设计挡土墙的抗滑稳定性、抗倾覆稳定性、基底应力及合力偏心距、截面应力等安全系数的验算，均满足要求。挡土墙最终截面按照拟定设计。第四章 排水设计4.1 气候与地质条件介绍 本路线区域属问亚热带，气候温和湿润，雨量充沛。48月为雨季，历年平均降水量1326.31468.4毫米。历年平均蒸发量1379.021390.03毫米，历年平均相对湿度8083，潮湿系数0.961.05，为湿度适中带湿度充足带.极端最低气温-8.5C，78月份气温最高，平均27.627.8C，极端最高气温39.9C.12月至翌年3月为雪期，全年有霜期8090天.本段基岩主要为白垩系中统。白垩系上统岩性主要为粉砂岩与粉质粉砂岩互层局部夹少量细砂岩。本合同段地下水一般贫乏，对边坡稳定影响不大，综合来看，本合同段场地稳定性较好。4.2 边沟的设计在K89+500至K89+700之间的左侧挖方段为挖方最大汇水面积段，本次设计以沥青混凝土路面为例。粘性土土路堑(坡度为1：0.5，坡面水流长度为8.945m)，路基宽度24.5m，取侧路面和路肩横向排水宽度为11.25m，路拱横坡为2%，在纵断面方面，此处纵坡i=0.802%，边沟坡脚和路肩边缘间设置梯形边沟。计算简图如图1。图一4.3 设计流量的确定与验算4.3.1 计算汇水面积和径流系数由图一计算汇水区域在路堑一侧(由平台沟到边坡平台)的面积A1=2237.2m2由于坡面上采用植草防护，则由公路排水设计规范得坡面径流系数取C1=0.5。汇水区域在边沟平台上的面积A2=147.03m2，取坡面径流系数(浆砌片石护面)C2=0.4，汇水区域在路面一侧(公路路中线到边沟)的面积为A3=1482.19m2，由表查得沥青路面径流系数为C3=0.95。由此，总的汇水面积为F=3718.66m2，汇水区的径流系数为C=(2237.20.5+147.030.4+1482.190.95)/3718.66=0.6954.3.2 计算汇水历时由克毕公式计算坡面汇流历时，式中：L为坡面长度；i为坡面坡度； t 1为坡面汇流历时； m地表粗糙系数；由表查得草皮防护路堑边坡的粗度系数m=0.4，且路堑坡度为1：0.5，得路堑坡面汇流历时t 1=1.445(0.423.42) /1.19 =3.858min由表查得边沟平台(浆砌片石护面)的粗度系数m=0.02，横向坡度为2%，则查表得沥青混凝土路面粗糙系数为m=0.013，横坡2%，坡面流长度为12.25m，所以历时时间为。因此取坡面汇流历时t=3.858min(取最大值)。设边沟底宽为0.6m，高0.6m，两边坡度为1：1，以浆砌片石砌筑，沟壁粗糙系数n=0.025。设计水深为0.5m。求得过水断面段面积为A=1/2(1.6+0.6)0.6=0.55m2，水力半径为R=0.4/0.6+0.4=0.273m。按曼宁公式，得沟内平均流速为：=1.33m/ s因此沟内汇流历时为：t2=L/V=105.494/1.33=1.332min。由上可得汇流历时为。t= t1+ t2=3.858+1.332=5.19min4.3.3 计算降雨强度据设计手册，高速公路路界内坡面排水设计降雨重现期为15年。求设计重现期和降雨历时内的降雨强度(mm/min)，由于公路在湖南通道至怀化境内，查公路排水设计规范，图3.0.7-1，可得湖南吉首至怀化境内5年重现期和10min降雨历时的标准降雨强度为q5，10=2.5，查公路排水设计规范表3.0.7-1 可知该地区15 年重现期期转换系数Cp=1.27， 查公路排水设计规范图3.0.0-2 得该地区60min 降雨强度转换系数C60=0.45，查公路排水设计规范表3.0.7-2 查得5min 降雨量的转换系数Ct=1.25，则：降雨强度I= cpctq5