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1、第4章 明洞设计4.1明洞长度确定进口端围岩等级为级，坡度比较平缓，因此有很长的超浅埋段。为了施工上的方便，考虑把超浅埋段设为明洞。坍落拱高度按下式计算当埋深时,即为超浅埋隧道。洞口段Xm处埋深为；斜坡坡度为，路面纵坡为1.2%。则有得在考虑岩石岩性考虑取明洞长度为50m。4.2明洞设置由于明洞围岩级别很差，垂直压力和侧向压力较大，故采用拱式明洞，并假设仰拱，明洞内轮廓线与暗洞内轮廓线一致。衬砌厚度为60m。衬砌材料采用钢筋混凝土结构，C25级混凝土，直径25mmHRB335级钢筋。明洞边墙用5#浆砌石片回填，拱部用挖土回填，最低回填土不小于1.5m，填土坡度设为，以利于排水。明洞配筋图如下：
2、4.3衬砌内力计算4.3.1基本资料回填土=18kN/m3，重度，计算内摩擦角，混凝土弹性模量，。4.3.2荷载确定 =6.336时属于浅埋。 4.3.3衬砌几何要素 计算图示如下图4.1级围岩内力计算图示1、衬砌几何尺寸内轮廓线半径：r1=5.70m，r2=8.20m内径所画圆曲线的终点截面与竖直轴的夹角：1=90，2=101.5725截面厚度：d=0.60m外轮廓线半径 R1=6.3m，R2=8.80m拱轴线半径 r1=6.00m，r2=8.50m拱轴线各段圆弧中心角 1=90，2=11.57252、半拱轴线长度S及分段轴长S分段轴线长度半拱轴线长度将半拱轴线等分为8段，每段轴长为3、各分
3、块接缝（截面）中心几何要素与竖直轴夹角另一方面 角度闭合差： 接缝中心点坐标计算4.3.4计算位移1、单位位移单位位移值计算如下计算精度校核为：闭合差 用辛普生近似计算，按计算列表4.1进行。表4.1单位位移计算表截面sincosxydI1/Iy/Iy2/I(1+y)2/I积分系数1/300.00000.00001.00000.00000.00000.600.018055.5560.00000.000055.55561113.2930.23000.97321.38020.16090.600.018055.5568.93891.438374.87174226.5960.44770.89422.6
4、8640.63500.600.018055.55635.27722.401148.51262339.8990.64140.76723.84851.39690.600.018055.55677.606108.41319.17414453.1920.80070.59914.80422.40560.600.018055.556133.46321.50644.34002566.4950.91700.39885.50223.60720.600.018055.556200.40722.881179.23944679.7980.98420.17725.90514.93710.600.018055.55627
5、4.281354.21958.28802792.1880.9993-0.03815.99386.32400.600.018055.556351.332221.82980.05664890.0001.00000.00005.82727.70520.600.018055.556428.063298.34210.03151444.481289.96304.29327.07852、载位移 （主动荷载在基本结构中引起的位移）竖向力 式中为衬砌外缘相邻两截面之间的水平投影长度水平压力 式中为衬砌外缘相邻两截面之间的竖直投影长度自重力 式中为接缝的衬砌截面厚度。作用在各楔块上的力均列入表4.2，各集中力均通
6、过相应图形的形心。（1）外荷载在基本结构中产生的内力楔块上各集中力对下一接缝的力臂由图中量得，分别记为内力按下式计算弯矩 (4-1) 轴力 (4-2) 式中为相邻两接缝中心点的坐标增值，按下式计算 （4-3） 第一截面的的计算见表4.2及表4.3表4.2弯矩计算表截面集中力力臂-Qaq-Gag-Eae(Q+G)Exy-x(Q+G)-yEMp0QGEaqagae00.0 000.0000.0000.00000.00000.00000.0000.0000.0000.0000.0000.00000.00000.0000.0000.0001199.26820.89021.0320.65560.6864
7、0.3764-130.640-14.339-7.9170.0000.0001.38020.1090.0000.000-152.8962184.52820.89060.1230.53810.62860.5105-99.294-13.131-30.693220.15821.0321.30620.4741-287.570-9.971-593.5563171.83620.890101.3790.43240.57700.6375-74.302-12.054-64.629425.57681.1551.16210.7619-494.562-61.832-1300.9344137.98320.890131.8
8、200.26150.45470.7093-36.083-9.499-93.500618.302182.5340.95571.0087-590.911-184.122-2215.0485100.77520.890157.0090.09130.32140.7505-9.201-6.714-117.835777.175314.3530.69801.2016-542.468-377.727-3268.993658.1 6320.890173.785-0.08370.17090.75134.868-3.570-130.564898.840471.3620.40291.3299-362.143-626.8
9、64-4387.266713.6 9520.890180.655-0.25640.00900.71433.511-0.188-129.042977.894645.1470.08871.3869-86.739-894.754-5494.47780.0 0020.890177.9540.0000-0.10570.65480.0002.208-116.5241012.479825.801-0.16661.3812168.679-1140.597-6580.711表4.3轴力计算表截面sincos(Q+G)Esin(Q+G)cosENp000.00001.00000.0000.0000.0000.00
10、00.00010.23000.9732220.15821.03250.63620.46930.16820.44770.8942425.57681.155190.53072.569117.96130.64140.7672618.302182.534396.579140.040256.53940.80070.5991777.175314.353622.284188.329433.95550.91700.3988898.840471.362824.237187.979636.25860.98420.1772977.894645.147962.443114.320848.12370.9993-0.03
11、811012.479825.8011011.770-31.4631043.23381.00000.00001033.3691003.7551033.3690.0001033.369基本结构中，主动荷载产生弯矩的校核为另一方面，从表12中得到闭合差 （2）主动荷载位移计算过程见表4.4。 表4.4主动荷载位移计算表截面Mp01/Iy/I1+yMp0/IMp0y/IMp0(1+y)/I积分系数1/300.00055.55560.00001.00000.0000.0000.00011-152.89655.55568.93891.1609-8494.206-1366.718-9860.92442-593.55655.555635.27781.6350-32975.354-20939.350-53914.70323-1300.93455.555677.60562.3969-72274.163-100959.778-173233.94044-2215.04855.5556133.64463.4056-123058.307-296029.063-419087.37025-3268.99355.5556200.40024.6072-181610.855-655106.677-836717.53246-4387.2
