计算公式和系数等取自建筑施工计算手册(第二版)173页本工程计算参数：土方为粉质粘土，重度Y=19.70KN/M3内按摩角=20,粘聚力C=28.50Kpa,地基承载力特征值fak=144Kpa,基坑开挖高度H=7.80米，土钉倾角G是10度，Sx水平间距1米，Sy竖向间距，取1.5米，土方侧压力P=28.50F(19.70X7.8)=0.1850.050.05的粘土Ka=0.406,=0.637=0.406X1-(2X28.50)F(19.70X7.80)X(1F0.637)X19.70X7.80=0.406X1-(57153.66)X1.569X153.66=26.20KN/M2=0.406X10=4.06KN/M2=30.26KN/m2土钉所受的拉力N(由上而下1-4道拉杆)N=(1Fcos0)XpSxSy=(1Fcos10)X30.26X1.00X1.501一4=(1F0.9848)X30.26X1.00X1.50=46.09KNN=(1Fcos0)XpSxSy=(1Fcos10)X30.26X1.00X0.305=9.21KN土钉墙安全系统Fsd=1.30土钉在破坏面一侧伸入稳定土体中的长度laLa=(1.30X46.09)F(3.14X0.1X50)=59.917F15.70=3.81mLh=(1.30X9.21)F(3.14X0.1X50)=11.973F15.70=0.76m5l匚二tan(86-45+4.70/2)X0.30=tan38.65X0.30=0.7997X0.30=0.239m5l4=tan(86-45+4.70/2)X1.80=tan38.65X1.80=0.7997X1.8=1.44ml3=tan(86-45+4.70/2)X3.30=tan38.65X1.80=0.7997X3.30=2.64m3l2=tan(86-45+4.70/2)X4.80=tan38.65X4.80=0.7997X4.80=3.8356m乙l=tan(86-45+4.70/2)X6.30=tan38.65X6.30=0.7997X6.30=5.00mL=Ln+LaL=0.76+0.239=0.999=1.00mL=1.44+3.81=5.25=5.5m54L3=2.64+3.81=6.45=6.50mL2=3.84+3.81=7.65=8.00mL=5.OO+3.81=8.81=9.OOm土钉墙钢筋直径d钢筋采用HRB335，取/y=335N/mm2由武2-195)Fs.d1聲香，可得#d=(4X1.3X44.7X1000)(1.1X3.14X335)=(2324401157.09)=7200.88=14.17mm用16钢筋边坡喷砼面层计算在土体自重及地表均布荷载Q作用下，喷砼面层所受的侧向土压力为P01=0.70X0.50+(1.50.5)F5X26.20=0.70X0.50+0.20X26.20=12.838KN/M2P0=1.2X(12.838+4.06)=20.2776KN/M2按四边简支板形式配制钢筋：lx/ly=1/1.5=0.666查简支双向板系数：W=0.007753Kx=0.069732Ky=0.02785Qx=1.4X20.2776=28.388KN/m皿=心4疋=0.0697X28.388X10002=19.78X105KN.mm计算选筋：_/c=11.9(C25砼)喷射砼面厚度为100mm,则h=80mmas=(19.78X105)-F(11.9X1000X802)=(19.78X105)F(76160X1000)=0.0259查表=0.9875，采用HRB235钢筋，/y=210N/mm2As=(19.78X105)F(80X0.9875X210)=(19.78X105)F16590=119.19mm2采用6200(141mm2)竖向配筋Qy=20.2776X1.0=20.2776KN/M=0.0279X20.2776X1500X1500=12.73X105N.mmAs二12.73X105F(80X0.9905X210)=12.73X105F16640.4=76.5mm2采用6200(141mm2)边坡稳定性验算设土体墙宽度5m(按墙宽一般取基坑深度的0.4-0.8)1.2F1=(7.8X5X19.7+5X10)Xtan20=(768.3+50)X0.3639=304.32KN刀N=46.09X4+9.21=193.57KNK1=F1Fn=304.32F193.57=1.5721.2所以边坡稳定。抗倾覆验算：土的自重平衡力矩：1.3M=(7.8X5X19.7+5X10)X(5F2)=818.3X2.5=2045.75kN.mwM0=193.57X7.8X(1F3)=503.28kN.mK2=2045.75F503.28=4.061.3乙所以土的抗倾覆符合要求。