重力式擋土墻設(shè)計(jì)

1、重力式擋土墻設(shè)計(jì)1. 設(shè)計(jì)目的在掌握檔土墻設(shè)計(jì)的基本原理前提下，進(jìn)行擋土墻設(shè)計(jì)，進(jìn)而掌握擋土墻尤 其是重力式檔土墻的設(shè)計(jì)方法。2. 題目描述和要求擋土墻設(shè)計(jì)初始條件：1）漿砌片石重力式仰斜路堤墻，墻頂填土邊坡1：,墻身縱向分段長度為10m,路基寬度26m,路肩寬度3. 0m；2）取汽車荷載邊緣距路肩邊緣 =0.5加；3）設(shè)計(jì)車輛荷載標(biāo)準(zhǔn)值按公路一一【級汽車荷載采用，即相當(dāng)于汽車一一 超20級、掛車120 （驗(yàn)算荷載）；4）粘性土地基與漿砌片石基底的摩擦系數(shù)/= 0.30,地基容許承載力0J=25OKP"；5）其他參數(shù)具體見以下中所述設(shè)計(jì)參數(shù)。3. 擋土墻設(shè)計(jì)計(jì)算書設(shè)計(jì)參數(shù)圖3-1-1

2、擋土墻參數(shù)圖如圖3-1-1,擋土墻墻體高為H=7m,基礎(chǔ)埋置深度D=1.5m,墻身縱向分段長度為L=10m；墻面與墻背平行，墻背仰斜，仰斜坡度1:, a = -14。，墻底傾斜度tana0 = , 傾斜角a()=° ;墻頂?shù)奶钔粮叨葹?a=3. Om,填土邊坡坡 1：, 0 = arctan(1.5)T =33.69°,汽車荷載邊緣距路肩邊緣d=O. 5m；墻后的填土為砂性土內(nèi)摩擦角0=35。，填土與墻背外摩擦角5 =(p/2=° ,填土容重/ = 18KN/m3；墻身采用號砂漿砌25號片石，墻身砌體容重n=22KN/m3,砌體容許壓應(yīng) 力b“ =600KPa,砌

3、體容許剪應(yīng)力r = 100KPa,砌體容許拉應(yīng)力 <rH/=60KPa；地基容許承載力<ro=25OKPa。車輛荷載換算經(jīng)常表可得q=,=0. 764mq 13.75KP" h 二=° / SKN/m主動土壓力計(jì)算3. 3. 1計(jì)算破裂角經(jīng)試算，按破裂面交于荷載中部進(jìn)行計(jì)算:ab+2/q)(b+d) H(H + 2a + 2h0)tanaA 、(a + H + 2h0)(a+H)3x4.5 + 2x0.764x5 + 7x(13+2x0.764)x0.25()4"(3+7 + 2x0.764)x10" *0 = 0 + a + / = 35&

4、#176; 14° + 175° =。90° (下式中間取加號)tan & 二-1an 屮 + J(cot0+ tan 0)(tan0 + A)=+ 7(1 -4281+0.7954)(0.4+0.7954)3. 3.2計(jì)算主動土壓力及其作用點(diǎn)位置3. 3. 2. 1計(jì)算主動土壓力Ka = cos(3 + <.(tan 6> + tan tz) = C°s748° x0.8346+ (-0.25) = 0.1565 sin(& +肖)sin 78.3°忙=0.855/?tan & +tana 0.5

5、846. b-atan34.5-3x0.8346 o . 1/?> = 3.4 mtan +tana 0.5846h、= H h? 一= 7.0m-0.855m-3.41 nz = 2.735m“,2a h. 2hk 2x3 仁 3.41 2x0.764x2.735Kt=l+1- +=1 +x 1- +H 2H) H17 k 14 J49Ea =丄困 2心& =1x18x49x0.1565x1.733 = 119.6/OV/wi 2 2Ex = Ea cos(a + 3) = 119.6xcos3.5° = 119.38KN/m1.733E、= Ea sin(a + J

6、) = 119.6 x sin 3.5 = 7.3KN /m3. 3. 2. 2計(jì)算主動土壓力的合力作用點(diǎn)H a(Hh$+hJh(3h2H)Z = +”33H*|73x (7 - 3.41)- + 0.764 x 2.735 x (3 x 2.735 -14)二 一 + = 2.44/n33x49x1.733因墻底傾斜，需要把求得的乙、Z、,修正為Z“、ZV1: 經(jīng)驗(yàn)算，取檔土墻頂寬為勺=2.0加，ZX1 = Zx b tana0 = 2.44-2.0x0.19 = 2.06mZvl =b Ztl tan or = 2.0 2.06 x (-0.25) = 2.525 m3. 3. 3被動土壓

7、力墻前被動土壓力忽略不計(jì)，偏于安全。檔土墻計(jì)算bi圖3-4-1 擋土墻計(jì)算圖3. 4. 1抗滑穩(wěn)定性驗(yàn)算墻身體積計(jì)算：V、=S(H 一勺 tan a0) = 2.0x(7.0 2.0x0.19)= 13.24/” 'V2 =0.5bf tan a0 = 0.5 x 2.O2 x 0.19 = 0.38nP墻身體積計(jì)算：q =叫兒=1324*x22KN/f = 29128KNG2 = V2yk =038r x22KN/F =836KNG = q + G = 192.28 KN + 8.36 KN = 299.64 KN穩(wěn)定性驗(yàn)算:l.lG + /fil(Ey + Ex tana() +

8、(1G + /eiEv)tana° -yQEx= 1x299.64+1.4(7.3 + 119.38x0.19)x0.3 + (l.1x299.64+1.4x73)x0.19-1.4x119.38 = 8.914>0 (則卩滿足條件)求抗滑穩(wěn)定系數(shù)：N = G + £ = 299 64KN + 7.3KN = 306 3 KNK _N + &tanqJ“_(30694 + 11938x019)x03_c Et-tana0119.38 - 306.94 x 0.19- ' c 即檔土墻滿足抗滑穩(wěn)定性要求。3. 4.2抗傾覆穩(wěn)定性驗(yàn)算墻身自重力臂計(jì)算：ZC

9、I =O5(H-Z>ltanao)n+Z>J = O.5x(7-2.OxOJ9)xO.25+2.O = 1.83mZG2 = 0.5 +1 /3(0.5 一 tan a tanajbx = 0.5 +1 /3(0.5 + 0.25 xO. 19)x 2.0 = 1.365m抗傾覆穩(wěn)定系數(shù)計(jì)算:EZ"8.36x1.83 + 299.64x1.365 + 7.3x2.515119.38x2.06= 229>K(J = 15即擋土墻滿足抗傾覆穩(wěn)定性要求。3. 4.3基底合力偏心距驗(yàn)算Zn =(GiZgi +GZg 嚴(yán) E、Z 譏一 EgiN =562.8133-119.6

10、x2.515 =1 0w306.94B = b、+ bx tan a tan tz0 = 2 + 2 x (-0.25) xO. 19 = 1.905 m1.905w-1.0. =0.045,< = = 0.3175.6 6即基底合力偏心距滿足要求。3. 4.4地基承載力驗(yàn)算2汕計(jì)警Z汁計(jì)心錯(cuò)）1.905i只氣93=< 37 （kPd）<b（） = 250kPa即地基承載力滿足要求。3.4.5墻身強(qiáng)度驗(yàn)算墻面與墻背平行，截面最大應(yīng)力位于接近基底處，由基底應(yīng)力計(jì)算結(jié)果知墻 身正應(yīng)力滿足墻體材料強(qiáng)度要求。墻身剪應(yīng)力及彎拉應(yīng)力很小，計(jì)算從略。4. 總結(jié)通過此次課程設(shè)計(jì)，我了解了擋土墻設(shè)計(jì)的基本原理，初步掌握了重力式擋 土墻設(shè)