1、直墻拱結構的設計計算步驟一、計算步驟1. 計算結構的幾何尺寸；2. 計算作用在結構上的荷載；3. 計算拱頂變位；4. 計算側墻的彈性特征值a及換算長度l=ah，判別側墻所屬類型5. 計算墻頂的單位變位6. 計算墻頂力，7. 計算拱頂未知力，8. 考慮彈性抗力時，計算9. 計算拱圈截面內力10. 計算側墻截面內力11. 繪制內力圖，校核計算結果12. 計算拱圈、側墻截面的內力和偏心距13. 計算拱圈和側墻各截面的安全系數14. 計算配筋量15. 繪制結構施工圖16. 計算工程量二、計算實例（一）設計基本資料結構斷面如圖所示。1、巖石特征軟質石灰巖，隧道埋深H=50m，巖石堅硬系數，內摩擦角j=6

2、50，容重g=24kN/m3，側向巖層地基系數K1=2.5×105kPa/m，基底巖層地基系數K2=3.125×105kPa/m。2被覆材料采用C20砼，彈性模量E=2.55×104MPa，容重g=25 kN/m3，砼軸心抗壓強度設計值，彎曲抗壓強度設計值，抗拉強度設計值。鋼筋采用25MnSi鋼：強度設計值，彈性模量。3結構尺寸凈跨，拱頂砼厚度（預先確定），拱腳厚度，內拱矢高，側墻厚度，內墻高，底板厚度，墻基埋深（二）結構幾何尺寸計算1拱圈內圓幾何尺寸內圓凈跨：，內圓矢高內圓半徑計算：，從而有：2拱圈軸線圓的幾何尺寸拱腳截面與拱頂截面厚度之差：軸線圓與內圓的圓心距

3、：軸線圓半徑：計算跨度：計算矢高：3拱圈外圓幾何尺寸外圓跨度：外圓矢高：外圓半徑：外圓與軸線圓的圓心距：4校核公式外圓與軸線的圓心距：5側墻的幾何尺寸拱腳中心到側墻中心線的垂直距離：側墻的計算長度（從拱腳中心算起）：結構總高：（三）計算拱頂單位變位采用分塊總和法計算變位，將半拱軸線長分10等分，計算過程列于表1，故拱頂單位變位：校核計算：判別： 說明單位變位計算結果正確。表1 變截面圓拱拱頂單位變位計算（見附圖）（四）計算拱頂載變位1計算荷載（1）巖石堅固系數，隧道半跨度：（考慮到有一定的間隙）隧道埋深H=50m>(2-2.5)h1，屬于深埋因此圍巖豎直壓力：（采用均布荷載模式）（2）自

4、重計算因此：在實際設計中，外載還應包括超挖回填引起的拱頂荷載，一般取30cm回填高度，可忽略不計。2計算載變位先分別計算在均布荷載和三角形荷載作用下的載變位，然后疊加，計算過程列于表2。表2 變截面圓拱拱頂載變位計算(見附圖)2計算載變位先分別計算在均布荷載作用下河三角形荷載作用下的載變位，然后疊加，計算過程列于表2.在均布荷載q作用下的載變位：在三角荷載作用下的載變位：拱頂總載變位：校核計算：，可見計算正確。 , 滿足要求！（五）在荷載作用下多余未知力的計算1判別側墻類型側墻特征長度：，故側墻屬于長梁2計算墻頂單位變位3由外載引起的墻頂彎矩與水平力4計算多余未知力（六）彈性抗力作用下多余未知

5、力的計算1計算時引起的墻頂截面內力及變位通過積分可得到：因此墻頂內力（要考慮偏心距）：墻頂變位：2計算時的拱頂載變位采用分塊總和法計算，將彈性抗力所分布拱軸線長對應圓心角四等分3計算時的多余未知力 4計算彈性抗力根據及從而可求得 5.在彈性抗力作用下多余未知力計算 （七）計算彈性抗力及外載共同作用下的多余未知力 將q=100.06kpa及=35.6kpa代入得 （八）計算拱圈內力1.拱圈任一截面的內力各截面的內力計算見表3（九）計算側墻內力 側墻為長梁，其任一截面的彎矩與軸力為現將側墻分為6等分：側墻各截面的內力計算見表4附表表1 變截面圓拱拱頂單位變位計算截面號化為弧度0000100.70.

6、34334.98542274116.1927150.1080830.1078730.9941646880.042597780.7033038370.34787959934.494693134212.385430.2161670.2144870.9767268540.169893970.713176790.36273678833.081838982318.578150.324250.3185980.9478900070.380402950.7295036360.38822400230.909989964424.770860.4323330.418990.9079906930.671667940.

7、7520938290.42541821128.207537192530.963580.5404160.5144930.8574945611.040289710.780683730.47580103825.220625954637.156290.64850.6039910.7969909321.48196620.8149396740.54122317522.171999582743.349010.7565830.6864410.7271859211.991542780.8544618750.6238469719.235486564849.541720.8646660.7608790.648894

8、1972.563072360.8987890840.72606143116.527527142955.734440.9727490.8264370.5630294723.189884850.9474039730.85036544714.1115799541061.927151.0808330.882350.4705938433.86466495111211.42857142934.9854227434.9854227001.42857142934.9854227434.985422745.687442311137.1736233137.9787735.877589110.2503722365.

9、621259972143.8563616149.9843232.80435374264.6238409966.16367811.240809861.9097458022.6753404277.4044878290.555043485.483180349117.1970824123.6399647.0330051417.891493784.926612682170.672965235.59746392.65924266651.2243624856.415074437.892196925.45097392.192404994.30727127157.65044215.12371380186.506

10、19827100.882504104.9470304109.17531563.767450984205.8295342419.95188032.45416938635.341765244.343999265.7163079397.389347141.558875006110.0603071273.16596224.68130892255.9511000276.9419462153.2331773305.17042742.475473178230.1751235688.57872822.22521616721.449232933.055054384.7224961217.14988830.936

11、957705117.7775504419.64993484.22206377931.7809416656.4463198180.0572605574.36192761.338403451236.5035803990.922768315.6471261131246.37597938179.22762190.22145856558.37597938283.9795807742.852731737.09585261527.97711427.142808293745.02155表2變截面圓拱拱頂載變位計算截面號x²x³垂直均布載q00.000000 0.000000 0.00000

12、0 0.000000 0.000000 0.000000 0.000000 0.00000010.78747250.6201130.4883219-31.024252748.49979527-4280.688312-182.347810148.0600040621.56575482.4515883.8385856-122.65294733.6035471-8115.170088-1378.71845692.0430594932.32576375.409176612.580466-270.621106874.142769-33459.58278-12728.12391385.353472643.

13、05862959.355214128.614133-468.0413627128.23051-26404.58829-17735.11547309.621234453.755799114.10602752.979404-705.7245338193.349187-71195.25797-74063.69413849.490620264.409136319.44048385.715738-972.6073496266.467767-43129.29949-63916.16408521.197827375.011016125.110282125.82803-1256.267404344.18285

14、-96659.65906-192501.84591171.66104385.554414230.851517171.3621-1543.501374422.877089-51020.5217-130769.2891610.604854596.032988836.396953219.58241-1820.939582498.887557-102785.338-327873.39261185.92873106.441154641.488473267.23367-2075.668308568.676249-24908.0197-96261.15066267.6155412-461958.1254-9

15、17409.84215441.576388垂直均布載q0.0000000.0000000.0000000.0000000.0000000.0000000.000000-4463.036122-0.8996423370.184858014-124.13155-5.2877280021.045234225-129.4192733-9493.888544-7.0718798211.453125991-467.90158-79.49365643.980239392-547.3952354-46187.70668-23.177169094.762432004-2865.6243-1090.0919132

16、4.75251108-3955.716168-44139.70376-52.7162177310.83209953-2973.9893-1997.53330226.15483647-4971.522646-145258.9521-97.604696120.05575947-9846.6061-10243.3230188.11611668-20089.92914-107045.4636-157.915300432.4483494-7002.5959-10377.6105163.46737317-17380.20646-289161.5049-231.814729547.63316359-1783

17、6.276-35521.70754162.1519552-53357.98398-181789.8108-315.702790664.87043643-10435.573-26747.1284593.66836004-37182.70133-430658.7306-404.539743583.12460482-22834.78-72840.31796197.5993503-95675.0977-121169.1704-492.3283243101.1633543-5907.9399-22832.2082147.60685164-28740.1481-1379367.967-80295.418-

18、181734.7023708.5428282-262030.12表3 拱圈各截面的M N值截面號057.8339700057.833970682.774157.8339729.0846550-31.9238950854.99473010678.7898007257.83397115.999180-129.724826844.1083280666.8837007357.83397259.729240-293.798275923.76493610647.1946518457.83397465.59740-520.75758052.673789520619.9524374557.83397750.2

19、8280-803.32922994.787540060585.4749911657.833971050.8480-1130.52265-21.840680544.1646863757.833971389.7740-1488.082134-40.4741640496.50364857.833971754.99120-1859.204164-46.3789940443.0480863957.833972121.652-9.00303-2225.479325-54.9963850.76911384.4218851057.833972464.693-16.80556-2567.996633-62.27

20、522310.08215321.30924040682.7742023.3458890975.39142868.684653287687.47445397588.10536323.2364273887.15539535.05667312701.94037382918.369209495.8133281922.67617978.90520099726.09985282938.295751117.736363773.869031139.0626099759.0150472150.8420348101.3157591832.693134213.4049468798.8799379482.979028

21、6502.4381133509.924315298.9161164843.0808027-968.5030939-1435.28881649.024524391.8160141888.319654-3114.160925-6201.98473024.001723487.7475251930.7956115-1533.060178-3929.34421344.003575582.0121615967.2031565-3104.343553-9902.49852299.183446669.83960311001.230994-747.3026701-2888.0744471566851-21816.65124689.09589表4 側墻各截面M 、N值截面1100.000001.00000.00