土力学与地基基础实训报告

PAGE/r/nPAGE/r/n11/r/n/r/n//r/n11/r/n土力学与地基基础实训报告/r/n土力学与地基基础实训报告桩基础设计/r/n某场地土层情况如下，第一层为杂填土，厚度/r/n1m/r/n，第二层为淤泥，流塑状态，厚度/r/n6.5m/r/n，第三层为粉质粘土，/r/nIL=0.25/r/n，厚度大。现需设计一框架柱，截面为/r/n300mm×450mm/r/n，桩预采用预制桩基础。柱底在地面处的设计值为：轴向力/r/nFk=2500KN/r/n，弯矩/r/nMk=180KNM/r/n，水平力/r/nH=100KN/r/n，水平力合弯矩方向均自沿长度方向左向右，初选柱截面/r/n350mm×350mm/r/n，桩基等级为二级。试设计此桩基础。/r/n1/r/n1m/r/n6.5m/r/n第三层粉质粘土厚/r/n度大/r/nFk=2500KN/r/n弯矩/r/nMk=180KNM/r/n350mm×350mm/r/n，桩基等级为二级/r/n2/r/n、确定桩长及单桩竖向极限承载力标准值。/r/n取承台埋深/r/nd=1m/r/n，桩端进入粉质粘土层/r/n3.5m/r/n（〉/r/n2d/r/n），桩的计算长度/r/nl=6.5m+3.5m=10m/r/n8-1/r/nqsik/r/n的值。淤泥层：流塑状态的淤泥（偏好）/r/n可取/r/n4.85/r/n〈/r/n5m,/r/n0.8/r/n。/r/n得：/r/nqsik=15×0.8kpa=12kpa/r/n。/r/n13/r/n粉质黏土层：埋深：/r/n2+6.5+1=9.25m/r/n0.96/r/n2/r/n得：/r/nqs2k=82×0.96kpa=78.7kpa/r/n。/r/n8-2/r/nqpk/r/n值：按/r/nI1=0.25/r/nh=11m/r/nqpk=4400kpa/r/n。/r/n单桩竖向极限承载力标准值为：/r/nQuk=Qsk+Qpk=u∑qsikli+qpkAp/r/n=0.35×4×(12×6.5+78.7×3.5)KN+4400×0.35KN=1033.83KN/r/n确定基桩的竖向承载力设计值。/r/nηC=0/r/n，按及/r/nBc=0.2lSa=3,/r/nηs=0.80/r/n，/r/nηp=0.4,γP=γs=1.65/r/n，于是基桩（/r/n数超过/r/n3/r/n根）的/r/nd/r/n竖向承载力设计值为：/r/nR=ηsQsk/γs+ηpQpk/γP=0.8×494.83/1.65KN+1.64×539/1.65KN=775.65KN/r/n初选桩的根数和承台尺寸。/r/n桩的根数：/r/nn>F/R=2500/775.65=3.2/r/nn=4/r/n取桩距/r/nSa=3.0d=3.5×0.35m=1.225m,/r/n（/r/n4/r/n）基桩的竖向承载力验算。/r/nN=(F+G)/n=(2500+1.2×20×1.75×1)/4KN=643.4KNNmax=N+MyXmax/∑Xj=643KN+/r/n（/r/n81+100×1/r/n）/r/n×0.525/4×0.525KN=776.7KN/r/nγsafN=1.0×643.4KN=643.4KN,/r/n重力式挡土墙/r/n设计一浆砌快石挡土墙，墙高/r/n5m/r/n，墙背竖直，光滑，墙后填土水平，墙后两层土体，第一层土为碎石土，层厚/r/n2m/r/n，物理力学指标：重度/r/nγ=-15KN/m/r/n，内摩擦角/r/nΦ=35°/r/n，粘聚力/r/nc=5KPa/r/n，第二层土为强风化泥质粉砂岩，重/r/nγ=22KN/m/r/n，内摩擦角/r/nΦ=30,/r/n粘聚力/r/nC=10KPa/r/n，基底摩擦系数/r/nu=0.4,/r/n地基承载力设计值/r/nfa=300KPa/r/n。/r/n1/r/n、初步确定挡土墙的顶宽、底宽和高度/r/n:/r/n挡土墙截面尺寸的选择：根据规范要求可知/r/nH=5./r/n则取顶宽/r/n0.8cm/r/n，底宽/r/n2.6m2/r/n、挡土墙断面的初步设计：/r/n(1)/r/n主动土压力计算：根据朗肯土压力理论则/r/nKal1/r/n，/r/nKal2/r/n：/r/nKal1/r/n＝/r/ntan/r/n（/r/n45°/r/n－/r/n35°/2/r/n）＝/r/n0.27Kal2/r/n＝/r/ntan/r/n（/r/n45°/r/n－/r/n30°/2/r/n）＝/r/n0.33/r/n（/r/n2/r/n）墙顶土压力强度为：/r/nσa/r/n＝/r/nqka1/r/n－/r/n2c1ka1/r/n＝/r/n0×ka1/r/n－/r/n2c1ka1/r/n＝/r/n0/r/n－/r/n2×5×0.27=-100.27/r/n＝/r/n-5.2kpa/r/n设临界深度为/r/nz0/r/n，则有/r/nσaz0/r/n＝/r/nγ1z0ka1/r/n＋/r/nqka1/r/n－/r/n2c1ka1/r/n＝/r/n0/r/n可得/r/n:18z0×0.27/r/n＋/r/n0/r/n－/r/n2×50.27/r/n＝/r/n4.86z0/r/n＋/r/n0/r/n－/r/n100.27/r/n＝/r/n04.86z0/r/n－/r/n5.2/r/n＝/r/nz0/r/n＝/r/n1.07m/r/n(3)/r/n第一层底部土压力强度/r/nσa/r/n＝/r/nγ1h1ka1/r/n＋/r/nqka1/r/n－/r/n2c1ka1/r/n＝/r/n18×2×0.27kpa/r/n－/r/n2×50.27/r/n＝/r/n4.52kpa/r/n第二层顶部土压力强度/r/nσa/r/n＝/r/nγ1h1ka2/r/n＋/r/nqka2/r/n－/r/n2c2ka2/r/n＝/r/n18×2×0.33/r/n－/r/n2×100.33/r/n＝/r/n0.39kpa/r/n第二层底部土压力强度/r/nσa/r/n＝/r/n(γ1h1/r/n＋/r/nγ2h2)ka2/r/n＋/r/nqka2/r/n－/r/n2c2ka2/r/n＝/r/n(18×2/r/n＋/r/n22×3)×0.33/r/n－/r/n22×100.33/r/n＝/r/n22.171kpa/r/n墙背上的主动土压力为/r/nEa/r/n＝/r/n1/2×4.52(2/r/n－/r/n1.07)kn/m/r/n＋/r/n0.39×3kn/m/r/n＋/r/n1/2(22.171/r/n－/r/n0.39)×3kn/m/r/n＝/r/n35.94kn/m/r/nEa/r/nx/r/n为/r/n:x/r/n＝/r/n1/3×5/r/n＝/r/n1.67m/r/n的/r/n自重：Ｗ/r/n1/r/n＝/r/n1/2×(2.6/r/n－/r/n0.8)×5×22kn/m/r/n＝/r/n99kn/m/r/nＷ/r/n2/r/n＝/r/n0.8×5×22kn/m/r/n＝/r/n88kn/m/r/nＷ/r/n1/r/n与Ｗ/r/n2/r/n的作用点离Ｏ点的距离分别为：/r/na1/r/n＝/r/n2/3×1.4/r/n＝/r/n0.93ma2/r/n＝/r/n1.4m/r/n＋/r/n1/2×0.8/r/n＝/r/n1.8m/r/n3/r/n、挡土墙的稳定性验算/r/n抗倾覆稳定运算：/r/nKt/r/n＝（Ｗ/r/n1×a1/r/n＋Ｗ/r/n2×a2)/Ea/r/nＸ＝（/r/n99×0.93/r/n＋/r/n88×1.8/r/n）/r/n//r/n（/r/n35.94×1.67/r/n）/r/n＝/r/n4.17>1.6/r/n满足条件/r/n抗滑动稳定运算：/r/nKs/r/n＝〔（Ｗ/r/n1/r/n＋Ｗ/r/n2/r/n）/r/n×u/r/n〕/r/n/Ea/r/n＝〔（/r/n99/r/n＋/r/n88/r/n）/r/n×0.4/r/n〕/r/n/35.94/r/n＝/r/n2.08>1.3/r/n满足条件/r/n4/r/n、挡土墙的排水设计/r/n挡土墙应设置池水孔，其间距宜取/r/n2-3m/r/n，外斜坡度宜为/r/n5/r/n％，孔眼尺寸不宜小于/r/nΦ100mm/r/n。林宗元/r/n./r/n岩石土层治理手册/r/n[M]./r/n沈阳/r/n:/r/n辽宁科学技术出版/r/n社/r/n,1993/r/n冯国栋/r/n./r/n土力学/r/n[M]./r/n北京：水利电力出版社，/r/n1988./r/n张力霆/r/n./r/n土力学与地基基础桩基工程/r/n[M].,/r/n北京：高等教育出版社，/r/n20xx/r/n良/r/n./r/n土力学/r/n[M].2/r/n版/r/n./r/n北京：中国水利电力出版社，/r/n20xx./r/n黄生根/r/n,/r/n张希浩/r/n,/r/n曹辉/r/n./r/n地基处理与基坑支护工程/r/n[M]./r/n北京/r/n:/r/n中国地质大学/r/n出版社/r/n,1999./r/n夏明耀，曾进伦/r/n./r/n地下工程设计与计算手册/r/n[M]./r/n北京：中国建筑工业出版社，/r/n1999/r/n扩展阅读：土力学与地基基础实习报告/r/n湖南交通工程职业技术学院/r/n0908/r/n学号：/r/n20xx00001497/r/n指导老师：王年生/r/n时间：/r/n20xx/r/n12/r/n26-20xx/r/n12/r/n目录/r/n第一章：概述/r/n1/r/n、桥墩基础设计已知资料/r/n2/r/n、设计资料/r/n3/r/n、桥墩上部结构设计标准图第二章：天然地基浅基础设计/r/n1/r/n2/r/n3/r/n4/r/n、基础自重的计算/r/n5/r/n、基础台阶土重的计算（按计浮力与不计浮力两种情况）/r/n6/r/n、根据《规范》要/r/n求进行最不利荷载组合/r/n7/r/n、地基强度及偏心计算（按计浮力与不计浮力两种情况/r/n第三章：地基沉降计算/r/n1/r/n、各分层自重应力及平均自重应力计算/r/n2/r/n、附加应力及平均附加应力计算/r/n3/r/n、/r/n地基总沉降量计算/r/n一．检算土的物理指标/r/n第一层土的筛分实验分析表/r/n筛孔直径/r/n(mm)/r/n分计筛余量/r/n分计筛余百分率/r/n(%)1/r/n1/r/n1-12/r/n2/r/n、确定土的密实程度/r/n:/r/n相对密实度：/r/nDr=emax-e/emax-emin=0.71-0.66/0.71-0.51=0.25/r/n1-5/r/n知，/r/n该土属于稍松状态/r/n3/r/n、确定土的状态及名称：/r/n塑性指数：/r/nIP=WL-WP=32.3-18.1=14.2/r/n1-8/r/n可知，该土属于砂黏土/r/n液性指数：/r/nIL=W-WP/IP=24.6-18.1/14.2=0.46/r/n1-9/r/n4/r/ne=0.66,IL=0.46/r/n；/r/n6-5/r/nσ0=318kPa/r/n021456289100021241727110>1010/r/n～/r/n2/r/n～/r/n0.521852150.5/r/n～/r/n0.251540.25/r/n～/r/n0.1246100/r/n第二层土的计算与分析/r/n1/r/n、确定土的状态及名称：塑性指数：/r/nIP=WL-WP=35-15=20/r/n1-8/r/n土为黏土/r/nIL=W-WP/IP=30-15/20=0.75/r/n1-9/r/n2/r/n、/r/n确定土层的基本承载力：由/r/n6-6/r/nσ0=175kPa/r/n二、设计计算/r/n（一）、初步拟定基础埋置深度和尺寸/r/n91.2-90.3=0.9m,/r/n2.0+0.9×10%=2.09m,/r/n88.00m/r/n，详细尺寸见尺寸长度宽度高度襟边宽体积层数上层下层合计/r/n(m)(m)(m)(m)0.50.81.3(m)/r/n自重/r/n(kN)/r/n水浮力/r/n(kN)157.6312.54.793.291.06.394.891.011.188.182.015.76362.4831.25718.7547.011081.23470.1/r/n（二）、基础本身强度检算/r/nα/r/nα/r/n层数上层下层/r/narctg0.5=26°arctg0.8=38°arctg0.5=26°arctg0.8=38°45°45°/r/n横向夹角/r/nα/r/nααmax/r/nαmax/r/n（三）、确定持力层及软弱下卧层顶面容许承载力/r/n1/r/n、持力层为黏性土：基本承载力/r/nσ0=318kPa/r/n容许承载力/r/n[σ]=σ0+k1γ1(b-2)+k2γ2(h-3)/r/n因为/r/nh/r/n=333.55kPa/r/n考虑主力加附加应力/r/n[σ]/r/n可提高/r/n20%[σ]/r/n主/r/n+/r/n附/r/n=1.2×333.55=400.26kPa(/r/n四/r/n)/r/n、持力层及软卧下层顶面强度检算（按计浮力计算）/r/n1/r/n、作用于基础底面下卧层的荷载计算/r/n(1)/r/n、基础自重/r/nN1=47.01×23=1081.23kN(2)/r/n、基础襟边上覆土重/r/n①/r/n墩身各部分面积计算基顶处墩身截面面积/r/n:d=2.29A1=1.5×2.29+π/4×2.29=7.55/r/n局部冲刷线墩身截面面/r/n积/r/n:d=(2.29/2-0.3/51)×2=2.28A2=1.5×2.28+π/4×2.28=7.50/r/n一般冲刷线墩身截面面/r/n积/r/n:d=(2.29/2-0.8/51)×2=2.26A3=1.5×2.26+π/4×2.26=7.40/r/n墩身截面面积/r/n:d=(2.29/2-1.9/51)×2=2.22A4=1.5×2.22+π/4×2.22=7.20/r/n水位冲刷线墩身截面面/r/n积/r/n:d=(2.29/2-3.2/51)×2=2.16A5=1.5×2.16+π/4×2.16=6.90/r/n设计频率水位处墩身截面面/r/n积/r/n:d=(2.29/2-4.2/51)×2=2.13A6=1.5×2.13+π/4×2.13=6.76②/r/n墩身各部分/r/n体积计算基顶至局部冲刷线处墩身体积/r/nV1=h1/3(A1+A2+A1A2)=0.3/3(7.55+7.50+7.55×7.5)=3.57m/r/n基顶至一般冲刷/r/n线处墩身体积/r/nV2=h2/3(A1+A3+A1A3)=0.8/3(7.55+7.40+7.55×7.0)=5.98m/r/n基顶至低水位冲/r/n刷线处墩身体积/r/nV3=h3/3(A1+A4+A1A4)=1.9/3(7.55+7.20+7.55×7.20)=14.01m/r/n基顶至常水位/r/n冲刷线处墩身体积/r/nV4=h4/3(A1+A5+A1A5)=3.2/3(7.55+6.90+7.55×6.90)=23.11m/r/n基顶至设计频/r/n率水位处墩身体积/r/n0./r/nV5=h5/3(A1+A6+A1A6)=4.2/3(7.55+6.76+7.55×6.76)=30.04m③/r/n考虑设计频/r/n率水位时，基础襟边上覆土重，自局部冲刷线算至基顶/r/nN2=(6.39×4.89×1.8-5.98-31.25)×20.3=386kNN2=(6.39×4.89×1.8-5.98-3/r/n1.25)×10.3=195.85kN④/r/n至基顶/r/nN3=(6.39×4.89×1.3-2.26-31.25)×20.3=144.36kNN3=(6.39×4.89×1.3-2.2/r/n6-31.25)×10.3=73.25kN/r/n(3)/r/n、水浮力计算/r/n由于基底于透水层中，故浸水部分的墩身及基础均受浮力考虑设计频率水位时，墩身及基础的体积/r/n:V6=30.04+47.01=77.05m/r/n水的浮力/r/n:N4=77.05×10=770.5kN/r/n积/r/n:V7=23.11+47.01=70.12m/r/n水的浮力/r/n:N5=70.12×10=701.2kN/r/n2/r/n、按设计资料所给的荷载表，将荷载移至基础底面。即增加基底水平力对基底产生的附加弯矩，也增加基础自重及基顶土重，得到基底所受的荷载，见表/r/n作用于基础底面的荷载计浮力：/r/n一孔轻载一孔重载双孔重载恒载荷载/r/n∑N∑M∑H∑N∑M∑H∑N∑M∑H∑N/r/n(KN)(KNm)(KN)(KN)(KNm)(KN)(KN)(KNm)(KN)(KN)/r/n基顶/r/n5109343427254623557272611431192724024/r/n荷载基础/r/n1081.231081.231081.231081.23/r/nN195.85195.85195.85195.85/r/n2/r/nN/r/n3/r/nN/r/n4N/r/n5/r/n水平附加弯矩基底荷载/r/n5650.53978827286795.4410127237563.2366327234561.654454454473.2573.257/r/n3.2573.25-543.6-543.6-543.6-543.6-612.9-612.9-612.9-612.9/r/n不计浮力：/r/n一孔轻载一孔重载双孔重载恒载荷载/r/n∑N∑M∑H∑N∑M∑H∑N∑M∑H∑N/r/n(KN)(KNm)(KN)(KN)(KNm)(KN)(KN)(KNm)(KN)(KN)/r/n基顶/r/n5109343427254623557272611431192724024/r/n荷载基础/r/n1081.231081.231081.231081.23/r/nN368368368368/r/n2/r/nN/r/n3/r/n重水平附加弯矩基底荷载/r/n6334.53978927236911.2410127237563.2366327235105.2544544544144.36144.3/r/n6144.36144.363/r/n、持力层强度检算/r/n三种荷载组合比较，以第三种荷载为最不利荷载组合/r/nσmax=ΣN/A+ΣM/W=5650.58/31.25+3978/25.47/r/n=337kPa/r/nσmin=ΣN/A-ΣM/W=5650.58/31.25-3978/25.47/r/n=24.64kPa/r/nσmax=337kPa1.5/r/n三、地基沉降量检算/r/n1/r/n、计算各分层上土的自重应力及平均自重应力/r/n已知：/r/na=6.39mb=4.8m/r/n2.8m/r/nΣN=4024kN/r/n2m/r/n2/r/n、从一般冲刷线起计算各底面处的自重应力及各分层的平均自重应力列于表：/r/n自重应力计算（不透水）/r/n平均自分层点编号土的容重/r/nγ/r/n土层厚/r/nγihi(kPa)i(kN/m)/r/n度/r/nhi(m)(kPa)(kPa)/r/n自重应力重应力一般冲刷线基底/r/n0ABCD20.320.320.320.319.22.8220.8256.8440.640.616.2438.480.84121.4416/r/n2.04178.28216.6852.24101.14141.75170.16197.4824/r/n自重应力计算（透水）/r/n平均自分层点编号土的容重/r/nγ/r/n土层厚/r/nγihi(kPa)i(kN/m)/r/n度/r/nhi(m)(kPa)(kPa)/r/n自重应力重应力一般冲刷线基底/r/n0ABCD3/r/n、计算基底底面处的附加应力：/r/n基底应力：/r/nσ=N/ab=4757.48/6.39×4.89=152.24kPa/r/n基底附加应力：/r/nσzo=σ-γh=112.02-20.3×2.8=95.4kPa(/r/n不透/r/n水/r/n)σzo=σ-γh=112.02-10.3×2.8=123.4kPa(/r/n透水/r/n)4/r/n、计算各分层面处的附加应力及各分层的平均附加应力见表/r/n附加应力计