第七章渗流分析.docx

1、第七章渗流分析6.6.1渗流分析说明渗流分析的目的在于：土中饱和程度不同，土料的抗剪强度等力学 特性也相应地发生变化，渗流分析将为土石坝中各部分土的饱水状态的划 分提供依据；检验坝的初选形式与尺寸，确定渗流力以核算坝坡稳定； 进行坝体防渗布置与土料配置，根据坝内的渗流参数与逸出坡降，检验 土体的渗流稳定，防止发生管涌和流土，在此基础上确定坝体及坝基中防 渗体的尺寸和排水设施；确定通过坝和河岸的渗水量损失，并计算排水 系统的容量。依据碾压土石坝设计规范(SL274-2001 )中8.1.2，渗流计算应 包括以下水位组合情况：1上游正常蓄水位与下游相应的最低水位；2上游设计洪水位与下游相应的水位；

2、3上游校核洪水位与下游相应的水位；4库水位降落时上游坝坡稳定最不利的情况；6.6.2渗流分析计算积石峡库区周边均为不透水岩层，封闭条件良好，因此渗流分析计算 模型为不透水地基均质坝。对均质坝在不透水地基上，有排水设备的情况, 不考虑均质坝上游坝壳料部分对渗流的影响。对棱体排水，浸润线逸出部 分如图所示。 y 在一单宽渗流量和均质坝下游坡渗流水深 h可由下面两式联立解除:2 2q kHi -(H2 ho)一 2Lho 二 L2 (Hi -出)2 -L式中k坝体的渗透系数，cm/s，其中k=0.45x 10 cm/s ；h坝前水深，mh坝后水深，mh棱体前水深，mL 透水区域，m。1.正常蓄水位时

3、的渗流分析上游水位为1856m下游相应水位假设为1791m则上游水深H1 =1856-1782=74m,下游水深 H2 =1791-1782=11m.L L 1H1 74 = 30.83m1+2g 1+2 汉 2.5L =(1865.07 -1856) 2.5 13 (1865.07 -1798)2.5-(1798 -1791) 1 =196.35mLlL L =42.59 169.59 = 227.18m代入式 h0 二 L2 (巴-H2)2 -L2 2kH1 (Hh0)ho=14.85m,代入式 2L ,k=0.45x10 -6cm/s渗流量为：q=5.1x10 -8/s,带入浸润线方程：

4、将渗流曲线坐标值列入下表中表6.6.2-1正常蓄水位渗流曲线坐标值x020406080100120140160180y7470.967.664.260.556.752.5484337.42.设计洪水位时的渗流分析上游水位为1858.22m,下游相应水位假设为1793m则上游水深H, =1858.22-1782=76m,下游水深 H2 =1793-1782=11m.|_ L 1 H1 76 = 31.7 m1+2m 1+2沢2.5L =(1865.07 -1858.55) 2.5 13 (1865.07 -1798)2.5-(1798 -1793) 1 =198.35mLlL L =31.7 1

5、98.35 = 230.02m代入式 h。一 L2 (H1-H2)2-LH12-(Hz+h。)2ho=9.O7m，代入式 q 2L ,k=0.45x10 -6cm/s_8 3渗流量为：q=5.3x10 m/s,带入浸润线方程：将渗流曲线坐标值列入下表中表6.6.2_2设计洪水位渗流曲线坐标值x020406080100120140160180y7672.869.465.862.158.153.849.24438.23.校核洪水位时的渗流分析上游水位为1862.45m,下游相应水位假设为1795,则上游水深H1 =1862.45_1782=80m,下游水深 H 2 =1795_1782=13m.|

6、_ L m1 H i 80 = 33.33m1 +2m1 1+2 7.5L =(1865.07 -1862.45) 2.5 13 (1865.07 -1798)2.5-(1798 -1795) 1 = 200.05mL l_ L =33.33 200.0233.68m代入式h。L2 (已一出)2 - L2 2q = k【H1 TH、 2Lho=9.41m，代入式， ,k=0.45x10-6cm/s渗流量为：q=5.6x10-8m/s,带入浸润线方程：将渗流曲线坐标值列入下表中表6.6.2-3校核洪水位渗流曲线坐标值x020406080100120140160180y8076.773.269.5

7、65.661.55752.247414.将前面几种工况计算所得的渗流曲线绘制在图 6.6.2-4中图6.6.2-3渗流曲线图结果分析；由于图中三种工况下的三条渗流曲线没有交点，说明渗流分析结果合理。6.6.3 稳定分析1.稳定分析的目的 对土石坝进行稳定分析的目的，是通过计算坝体剖面的稳定安全度来 检验坝坡在各种工况下是否安全，断面尺寸是否经济合理。 计算工况与安全系数(1)稳定渗流期。校核两种工况的上、下游坝坡稳定：上游为正常蓄 水位或设计洪水位至死水位之间的的某一水位，下游为相应的水位 的正常运用条件；上游为校核洪水位，下游为相应水位的非常运 用条件 I 。(2)水库水位降落期。校核两种工

8、况下的上游坝坡稳定：水库水位处 于正常蓄水位或设计洪水位与死水位之间的某一水位发生降落的正 常运用条件；水库水位自校核洪水位降落至死水位以下或是水库 以大流量快速泄空的非常运用条件 I ；(3)地震作用时。与正常运用条件的作用相组合验算上、下游坝坡的稳 定。属于非常运用条件 II2.稳定分析计算本次设计采用瑞典圆弧法，其中原理假定滑动面为一圆柱面。将滑动 面内的土体看成是刚体，失稳时土体绕圆弧的中心旋转，沿着坝轴线方向 取单宽段，按平面问题进行分析。计算时将滑动面以上的土体分成若干铅 直土条，求出土条对圆弧中心的抗滑力矩之和以及滑动力矩之和。二者的 比值为该滑动面抗滑稳定安全系数 Kc.3.最

9、危险圆弧的确定根据规范查的取B 1=25, B 2=35，在图中做出 M1, M2.如图663-1 所示：图 6.6.3-1 滑动面位置计算公式:二 Wi sin ajZ W cosctj tan 出 + 送 Gb kc式中:illll川川I川川I 土条编号：W |川川川I山川I 土条重量：bMl川川I山川I 土条宽度：a山I川川I山川I 土条沿滑裂面的夹角，单位（?）：C,丨川川川川川）1有效抗剪强度指标：4.稳定分析计算：设计洪水位上游坝坡稳定计算4.1 第一次试算：R=231.37m,b=23.13m。计算结果记入下表4.1-1中。图4.1-1设计洪水位上游坝坡稳定计算简图A1A2A3Y

10、 1Y 2Y 300149.0620.419.816.500447.8420.419.816.50122.49626.2520.419.816.50419.43622.4920.419.816.50721.21625.9920.419.816.501022.26625.9920.419.816.516.911305.1469.520.419.816.5323.621266.4895.6520.419.816.5417.57695.57020.419.816.5567.9451.56020.419.816.5W1W2W3ws ina刀 Wcosatan 0Cbseca002459.4901032

11、.99462.6007389.3603103.53462.602425.3010333.1305358.54462.608304.7110271.0907801.84462.6014279.9610328.84010335.69462.6020240.7510328.84012839.22462.6344.9625840.987746.7511605.6613392.25492.296601.8525076.301578.2317623.1911845.26545.498518.4313772.29014328.197171.78603.8811585.981020.8909657.42340

12、3.49719.68076284.595136.94T=81421.53S=53214.47K=1.531.5basi nacosaseca0tan 0c23.130.000.001.001.0023.000.4220.0023.130.000.001.001.0023.000.4220.0023.130.000.001.001.0023.000.4220.0023.130.000.001.001.0023.000.4220.0023.130.000.001.001.0023.000.4220.0023.130.000.001.001.0023.000.4220.0023.1320.000.3

13、40.941.0623.000.4220.0023.1332.000.530.851.1823.000.4220.0023.1340.000.640.771.3123.000.4220.0023.1350.000.770.641.5623.000.4220.00第二次试算：R=236.97m,b=23.3m。计算结果记入下表4.1-2中。A1A2A3Y 1Y 2Y 3W1W2W300110.4520.419.816.5001822.4300331.3520.419.816.5005467.28034.72513.2220.419.816.50687.468468.130232462.3320.

14、419.816.504593.67628.450453.84323.3220.419.816.508986.035334.780664.43131.2620.419.816.5013155.72165.790782.181.3520.419.816.5015487.222.280680.15020.419.816.50134670140.11358.25020.419.816.52858.247093.350191.655.04020.419.816.53909.6699.790W土ws ina刀 W土 cosatan 0CbsecaTS K1822.430765.424665467.2802

15、296.264669155.5903845.3546612222.0505133.2646614320.813706.505809.79482.4415321.504479.576153.85487.2944767.7328611.69 1.5615509.445304.546121.12495.9113466.976528.924946.96532.809951.595708.003423.78568.884009.452884.161169.78670.83合计28611.6939665.585102.16basi nacosaseca0tan 0c23.30011230.422023.3

16、0011230.422023.30011230.422023.30011230.422023.3150.260.971.04230.422023.3170.290.961.05230.422023.3200.340.941.06230.422023.329.000.480.871.14230.422023.3350.570.821.22230.422023.3460.720.691.44230.4220第三次试算 R=246.51m,b=25.35m计算结果记入下表4.1-3中。A1A2A3Y 1Y 2Y 3W1W2W300128.5220.419.816.5002120.5800385.57

17、20.419.816.5006361.91071.33572.520.419.816.501412.39446.250318.72581.2820.419.816.506310.79591.120582.02549.2520.419.816.50115249062.630863.43360.2520.419.816.50170965944.1301090.796.4920.419.816.50215951592.0955.881015.5020.419.816.51140201070382.97461.43020.419.816.57812.69136.30400.9711.59020.419

18、.816.58179.8229.480W土 wsina 刀 W土 cosatan 0 Cbseca T S K2120.580890.645076361.9102672.0050710858.5804560.6150715901.7806678.7550720586.6208646.3850763166.91 40021.23 1.5823040.044000.869529.80514.8223187.557930.619151.45539.5421247.4510623.727728.35585.4316948.9011119.485372.43671.788409.276346.56231

19、7.13772.80合计 40021.23 57547.54 5619.37basi nacosaseca0tan 0c25.350011230.422025.350011230.422025.350011230.422025.350011230.422025.350011230.422025.35100.17360.9851.015230.422025.35200.3420.941.064230.422025.35300.50.8661.155230.422025.35410.65610.7551.325230.422025.35490.75470.6561.524230.42204.2正常

20、蓄水位的下游坝坡的稳定计算第一次试算，取 R=253.3m,b=23.3m. 计算过程见表4.2-1 :表4.2-1下游坝坡稳定计算A1A2A3A4A5Y 1Y 2Y 3Y 4Y 500110.890110.8920.419.816.520.51800332.680332.6820.419.816.520.51800483.2971.18483.2920.419.816.520.518211.2949.52469.2627.92343.9220.419.816.520.518257.35253.01350.602.4120.419.816.520.518289.82439.23180.1100

21、20.419.816.520.518373.37516.6912.660020.419.816.520.518465.07350.0400020.419.816.520.518635.42100.9500020.419.816.520.518400.77000020.419.816.520.518W1W2W3W4W5WW堆石ws ina001829.701996.021829.6851996.020005489.205988.245489.225988.240007974.31459.28699.227974.28510158.4104310.32980.57742.8572.366190.5

22、613033.66762.923437.635249.945009.65784.9043.3816044.4443.384163.835912.338696.82971.80017580.906013.027616.7510230208.890018056.107915.279487.436930.800016418.2208700.3312962.571998.800014961.3809415.508175.7100008175.70805979.33刀 Wsina= 45624.92W土 cosata n 0W堆 cosatan 0 Cbseca刀 Wcosata n 0776.7016

23、74.864662451.562330.175024.734667354.913385.088523.9246611909.015448.715588.55473.1911037.266578.7935.16482.446613.957013.010495.917013.016889.090518.476889.095910.500549.505910.504935.740599.634935.742366.940683.292366.945200.4266481.96T=71682.4S=45624.9K=1.571.5满足要求basi nacosaseca00 tan 0tan 0 c23.3001123400.420.842023.3001123400.420.842023.3001123400.420.842023.3100.170.981.0223400.420.842023.3150.260.971.0423400.420.842023.3200.340.941.0623400.420.842023.3260.440.901.1123400.420.842023.3320.530.851.1823400.420.842023.3390.63